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What Future for

Lake Turkana?

African StudiesCentre

The impact of hydropower and irrigationdevelopment on the worlds largest desert lake

Sean Avery


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Crocodile Lake within Central Island

Front cover photo: Antonella865 | Dreamstime.com


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The landscape of the Lower Omo and LakeTurkana basin will soon undergo one of the biggesttransformations in its history, thanks to the Gibe IIIhydropower dam which is now under construction, 600

kilometres upstream from the lake. Due for completion in2014, Gibe III will permanently alter the natural hydrologicalcycles upon which the ood plains ecology, the productivityof Lake Turkanas sheries and the livelihoods of the localpopulation have always depended.

By regulating the ow of the river, the dam will also makepossible large-scale commercial irrigation schemes in the LowerOmo which is set to become the largest irrigation complexin Ethiopia. One of the schemes now being implemented willalmost equal in extent the entire current irrigated area of Kenya.Irrigation development on this scale will require a huge rate ofwater abstraction from the Omo, which is a trans-boundary riverand the source of 90 per cent of Lake Turkanas freshwater andaccompanying nutrient inow.

The result could be another Aral Sea disaster in the making,

with up to 50 per cent of the lakes Omo inow being abstractedfor irrigation alone. In this case the lake will drop by morethan 20 metres (its average depth is roughly 30 metres) and its

biomass volume will reduce drastically, as will its dependentsheries. Ultimately, the lake could reduce to two small lakes,the northern one fed by the Omo and the southern one by theKerio and Turkwel rivers.

What Future for

Lake Turkana?


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ETHIOPIA

KENYA

SOUTHSUDAN

Lake Turkana

Omo River

Lake Turkana

GIBE III DAM

KENYANE shores near Alia Bay, Sibiloi National Park

Small lake near the south end of Lake Turkana


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Contents

Acronyms 2Acknowledgements 3About the author 5

Introduction 7

The lake - its people, history and ecology 11Human occupation 11The lakes reducing drainage area 14Water quality and health 16Fisheries 18National parks 23

Irrigation water demand in the Omo Basin 25Potential irrigated area 26

Irrigation system efciencies 31Irrigation water demand as a percentage of Omo ow 32Failure to learn from experience 37

The impact on Lake Turkana of regulated and reduced Omo ows 39Water balance and ow duration curves 39Gibe IIIs dampening effect and the potential destruction of sheries 41Gibe IIIs lling period and water losses during operation 43Irrigation abstractions - a permanent lowering of the lake 46

What future for Lake Turkana? 49 References 53


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Figures

1 The Omo-Gibe hydropower cascade2 Peoples of the lower Omo and Lake Turkana3 South Island, showing the ancient shoreline4 Fishing community on North Island5 The Jade Sea, with South Island in the background6 Planned irrigation development in the lower Omo, 20117 Cultivation with terraces to control runoff and erosion, Ethiopian highlands8 Flood retreat agriculture in Kara territory, lower Omo9 Omorate, not far from the Omo delta10 Lake Turkana water balance model11 Proposed regulated ow sequence from the Gibe III dam12 Dampening effect of Gibe III and lake level changes13 The effect of Gibe III lling

14 Lake level falls for various abstraction rates, 1993-2012 ows15 Lake level falls for two abstraction rates, 1888-2011 ows16 Lake Turkana an African Aral Sea in the making?

Tables

1 Potential medium and large-scale irrigation areas in the Omo Basin2 Lower Omo irrigation potential annual water usage

African Studies CentreSchool of Interdisciplinary Area StudiesUniversity of Oxford13 Bevington RoadOxford OX2 6LH Publication date: December 2013

Photos, unless otherwise stated, Sean Avery Edited by David urtonDesign by www.harveygraphic.co.uk


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Goats on barren ground near the lake (South Island in the background)

South Island, Lake Turkana


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Acronyms

AFDB African Development BankAFD Agence Franaise de Development (French Development Agency)ADF African Development FundALRMP Arid Lands Resource Management Project, KenyaASAL Arid and Semi-Arid LandsARWG Africa Resources Working GroupEEPCo Ethiopian Electric Power CompanyEIB European Investment BankEPA Environmental Protection Authority, EthiopiaEVDSA Ethiopian Valleys Development Studies AuthorityEWCA Ethiopian Wildlife Conservation AuthorityEWRA Ethiopian Water Resources Authority

FoLT Friends of Lake Turkana, KenyaILRI International Livestock Research InstituteIUCN International Union for Conservation of NatureJICA Japan International Cooperation AgencyKETRACO Kenya Electricity Transmission Co. Ltd.KFS Kenya Forest ServiceKMD Kenya Meteorological DepartmentKMFRI Kenya Marine & Fisheries Research InstituteKNBS Kenya National Bureau of StatisticsKPLC Kenya Power & Lighting Co. LtdKWS Kenya Wildlife ServiceMALDM Ministry of Agriculture, Livestock Development and MarketingMoA Ministry of Agriculture, KenyaMoE Ministry of Energy, KenyaMoFD Ministry of Fisheries Development, KenyaMoLD Ministry of Livestock Development, KenyaMoLD&F Ministry of Livestock Development and Fisheries, KenyaMoWD Ministry of Water Development, KenyaMoWI Ministry of Water & Irrigation, KenyaMoWR Ministry of Water Resources, EthiopiaMoWRD Ministry of Water Resources Development , KenyaNEMA National Environment Management Authority, KenyaNIB National Irrigation Board of KenyaNIVA Norwegian Institute for Water ResearchNK Nippon Koei, Consultants, JapanNMA National Meteorological Agency, EthiopiaREGLAP Regional Learning & Advocacy Programme for Vulnerable Dryland CommunitiesUNEP United Nations Environment ProgrammeWDD Water Development Department, KenyaWHC World Heritage Centre (UNESCO)WRMA Water Resources Management Authority, Kenya


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What Future for Lake Turkana?

Acknowledgements

This paper, and the report on which it is based, were commissioned by the AfricanStudies Centre of the University of Oxford. I am grateful to Professor David Andersonand Dr David Turton for this opportunity and to Dr Turton for sharing his intimateknowledge of the Lower Omo and for his consistent support throughout. Myhydrological studies of Lake Turkana began in 2009, with a commission from the AfricanDevelopment Bank (AFDB) to report on the potential impact on the lake of the GibeIII hydroelectric dam. I was very grateful to the Bank for the chance to undertake thiswork, since a consolidated hydrological study of this type had not previously been done.

I am grateful also to the many scientists, professional colleagues and friends whosenames are included in my full report, and would mention in particular Ikal Angelei, the youthful champion of the NGO Friends of Lake Turkana, and also Dr Jeppe Kolding ofthe University of Bergen, Elina Rautalahti of UNEP, and Dr William Ojwang of KMFRI, fortheir encouragement.

It has been a privilege to have visited Turkana on many occasions over the past 34 years, and this would not have been possible without the enthusiastic participation ofmy family - my patient wife Carol, my shermen sons Patrick and Kieran, and my feistydaughter Kuki. We shared many weeks on safari together exploring these harsh but

fascinating areas.

Lake Turkana - the Jade Sea - south of Loiyangalani


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Fishing boats and children in Kalokol

South end of Lake Turkana

P h o t o : K i e r a n A v e r y


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About the author

Sean T. Avery (BSc., PhD., C.Eng., C. Env.) is a consulting civil engineerand hydrologist specialising in African water resources, particularly in Kenya andEast Africa. He was born in Tanzania and has lived in Kenya since 1979. He hasled many professional consultancies in the water, wastewater, irrigation, drainage,and environmental sectors over the past thirty years and more, working withmany African governments and international donors. His specialist interests are inengineering hydrology and arid zones, and his developing interests include waterresource conict resolution. He has written reports on the impact of river basindevelopment on the hydrology of Lake Turkana for the African Development Bankand the African Studies Centre of the University of Oxford. He has developeda strong working relationship with this university, and is a member of WaterResources Associates (www.watres.com), a network of international specialistconsultants based nearby in Wallingford. He is also an Associate of the Departmentof Geography at the University of Leicester, UK.

L a ke T u r k a n a & t he

Lo we r O mo :

H yd ro log ic a l I m p ac t s o f

M a jo r D a m & I r r ig a t io n

De ve lo p me n t

A f r ic a n S t u d ie s

C e n t r e

R E P O R T

D r Se a n A ve r y B Sc,

P h D, C E ng, C E n v

Co n s u l t a n t s e m a i l : se

a n @ w a t re s.co m We b

: w w w. w a t re s.co m

Lake Turkana& the Lower Omo:

Hydrological Impacts ofMajor Dam & Irrigation Development

REPORT

A CDcontainingthe reporton whichthis paper isbased canbe foundinside theback cover.


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Small lake amidst barren volcanic terrain at the south end of Lake Turkana

One of many reed fringed channels in the Omo Delta



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Introduction

Te Omo River drains south rom Ethiopias humid highlands to the semi-aridlowlands o the Lower Omo where the river nally terminates in Kenyas Lake

urkana. Te lake is a closed basin located north o the Equator within KenyasRif Valley, and in a climatically challenged area o extreme aridity. Te Omodelta, an ever-changing wetland with a multiplicity o channels and rich inbiodiversity, alters in response to varying lake level. Sediments are deposited,

orming banks to channels reaching sinuously out into the lake. At times o lakerecession, wetlands become stranded, lake margins recede, the river downcuts,and the delta retreats south into Kenya. At times o lake rise, the northern lakemargins inundate and the delta advances north into Ethiopia.

Te Omo carries 14 per cent o Ethiopias entire annual runoff and providesabout 90 per cent o the lakes annual inow. It thereby acts as an umbilical cord,supporting the ecology o the semi-arid and arid Lower Omo and arid Lake

urkana. Te richness o the rivers ecology has attracted, over the centuries,

people with a remarkable diversity o cultures and languages. Seasonal oodshave inundated pastures adjoining the river, sustaining both livestock and wildli epopulations and making ood-retreat agriculture 1 possible along the riverbanks.Te rivers ood pulses trigger sheries breeding and dilute the lakes semi-salinewaters. Te annual oods raise the lake level, and the inundated lake marginsprovide a ourishing habitat or breeding sh.

But the Omo Basin is undergoing dramatic man-made changes due tohydropower and irrigation development, with oil exploration also in progress.Te lling o dam reservoirs will cause temporary drops in the water level oLake urkana and, once in operation, the dams will permanently regulate riverows, changing the hydrological cycle. Te abstraction o water rom the Omo

or irrigation, downstream rom the dams, will cause a permanent reduction inlake level. Te change in water level, combined with alteration o the hydrologicalcycle by the dams, will lead to the destruction o the lakes ood plains sheries.Te impact on the human population will also be dramatic, with residents o theLower Omo being evicted rom their land and resettled elsewhere, to make way

or commercial agriculture.

1 Also known as ood recession agriculture.


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In 1996, a Master Plan was presented or the integrated development o the Omo-Gibe2 River Basin (Woodroo e et al. 1996). Major hydropower and irrigated agriculturepotential was identied in the Omo Basin, but the impacts o these developments onLake urkana were not studied. In 2006, construction o the massive 243 metre highGibe III dam began on the Omo, some 600 km upstream rom the lake.3 Te projectwill generate 1,870 MW o electricity, equivalent to the entire power generatingcapacity o Kenya. An environmental and social impact assessment (Agriconsulting,2009) was belatedly approved by the Ethiopian Governments EnvironmentalProtection Agency, three years afer construction had begun. Like the Master Plan, thisdid not consider impacts on Lake urkana or Kenya.

In 2009, the A rican Development Bank (AFDB), which was considering nancingthe Gibe III power station, commissioned hydrological and socio-economic studies

to assess the impact o the project on Lake urkana. Te hydrological studies (carriedout by the present author) revealed major hydrological and ecological impacts on Lakeurkana arising rom Gibe III and irrigation developments downstream (Avery, S. .,

2009 and 2010). Te AFDBs interest in the project ceased, however, when Chinesedonors stepped in to nance the power station in 2010. Completion o the dam islong overdue but it was reportedly 71 per cent complete in May 2013 and could beoperational by 2014. Te total cost is put at 1.47 billion Euros ( egegne, 2013). wo

urther hydropower dams downstream, Gibe IV and V, are at the planning stage, GibeIV comprising a major reservoir the size o Gibe III.

In 2011, large-scale irrigation development by the state-owned Ethiopian SugarCorporation began in the Lower Omo, covering a huge area never envisaged in theMaster Plan. Tis included the ood-retreat cultivation and grazing areas o thousandso resident agro-pastoralists, and vast areas taken rom two national parks and awildli e reserve. Te local administraton has begun a programme o what it describesas voluntary villagisation or traditional landowners, but there have been ongoingreports o orced evictions and other human rights abuses (e.g., Human Rights Watch,2012; Oakland Institute, 2013).

Once the extent o planned irrigation had become known, I was commissioned by theA rican Studies Centre o the University o Ox ord to update my AFDB study or aproject ocusing on environmental change in the Lower Omo.4 My terms o re erence

2 The Omo is named Gibe in its upper and middle basins.3 Gibe I, with a planned generating capacity of 184 MW, began operating in 2004. Gibe II is a power

house which draws its water through a 25 km tunnel from the Gibe I reservoir and has a generatingcapacity of 420 MW. It was inaugurated in January 2010 but had to shut down almost immediatelybecause of a tunnel collapse and did not resume operation until December of the same year.

4 This project, Landscape people and parks: environmental change in the Lower Omo Valley, was run

by Professor David Anderson and Dr David Turton and funded by the UK Arts and Humanities ResearchCouncil, under its Landscape and Environment Programme.


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were to consolidate and expand my earlier ndings, in the light o new in ormationabout the uture extent o planned commercial irrigation development in the LowerOmo. Tis paper, also commissioned by the A rican Studies Centre, is a condensed version o the resulting report, the ull version o which is included with the hardcopy o this paper on a CD.

Lake Turkana

Figure 1: The Omo-Gibe hydropower cascade.

(From CESI & Mid-day International, 2009, p. 46)


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Dried sh being stored near the lake

Spring water source near Loiyangalani



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The Lake - its people,history and ecology

Human occupationTe Lake urkana area has a ascinating human evolutionary history, and is ofenre erred to as the Cradle o Mankind. Te oldest known ossil remains o ouranatomical ancestor, Homo sapiens, dating back nearly 200,000 years, were discovered

in the Lower Omo in 1968 (MacDougall et al., 2005), making this the oldest landscapein the world known to have been inhabited by modern humans. 5 oday there arearound 52 different linguistic groups living in the Omo and urkana Basins, themajority o them within Ethiopia. Population densities vary according to climate,which governs livelihood opportunities. Te moist ertile highlands o the upper OmoBasin support 500-2,5006 persons per square kilometre, whereas in stark contrast, thedeserts east o Lake urkana sustain less than 5 persons per square kilometre (Avery,S. ., 2012, p.83). Tese deserts are the least densely populated area in the whole oKenya (ibid., p.81).

Te distribution o ethnic groups in the Lower Omo and around the lake is shownin Figure 2. Not only is this an area with many different languages, but the languagesrepresented all into two o the our major A rican language amilies, Nilo-Saharanand A ro-Asiatic. Te Nilo-Saharan speakers all into three sub- amilies, Surmic (Bodi,Kwegu, Mursi and Suri), Eastern Nilotic (Nyangatom, urkana and Samburu), andSouthern Nilotic (Pokot). Te A ro-Asiatic speakers all into two sub- amilies, Omotic(Hamar and Kara) and Cushitic (Dassanech, Gabbra, Elmolo and Rendille). Te Nilo-Saharan speakers extend rom South Sudan and Uganda, whilst the Cushitic speakersextend rom southern Ethiopia and Somalia. Te lake orms a natural north/southphysical divide between these groups. Cushitic communities on the eastern shores stillregard the lake as a physical barrier that protects them rom rustlers (Kaijage andNyagah, 2010).

Te predominantly agro-pastoral population o the the Lower Omo depends heavilyon ood-retreat cultivation along the banks o the Omo. Planting begins as the

5 The fundamental importance of this area in the study of human evolution was recognised by thedesignation of the Lower Valley of the Omo as a UNESCO World Heritage Site in 1980.

6 Data extracted from population mapping produced by Thomas Ballatore, Natasha Gownas, and AlfredBurian from LandScan 2008 (ORNL).


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Figure 2: Peoples of the Lower Omo and Lake Turkana (Base map from Carr, 2012)

KARA

HAMAR

TURKANA

SURI

DIZI

ETHIOPIA

KENYA

SOUTHSUDAN

Lake Turkana

Omo River

KENYA

TURKANA

EL MOLO

DASSANECH

GABBRA

Mago River

RENDILLE TURKANA

DASSANECH

MURSI

NYANGATOM

BODI

Ileret

Koobi Fora

Moite

Loiyangalani

Kalokol

Todenyang

North Island

FergusonsGulf

Central Island

South Island

NORTH

Lodwar

Turkwel River Kerio River

50 km

South Island National Park

Mount Kulai

Central Island National Park

Alia Bay, Sibiloi National Park

SAMBURU


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ood retreats in September/October, with the harvest coming in December/January.Rain all increases northwards rom the lake and this allows the Bodi, Mursi, Kwegu andNyangatom to practise some rain- ed cultivation, though with limited reliability. TeKwegu, who live in very small groups along the banks o the Omo, and are acknowledgedto have pre-dated their current neighbours in the area, are traditionally hunters andshermen.7 Immediately north o the lake, in Dassanech territory, the annual oodinundates large areas o grassland, away rom the river, thereby rejuvenating dry seasonpastures and making large areas available or cultivation.8

Although traditionally the urkana occupied the western side o the lake, some havecrossed at its narrowest point to occupy the eastern shore between El Molo Bayand Moite and north to Sibiloi National Park. Te urkana are Kenyas third largestpastoral group and they also cultivate along the Kerio and urkwel Rivers. Tey are

the lakes dominant shing community today and urkana shermen are active on allthe lakes shores.

Te Pokot occupy lands south-west o the lake within the Kerio Valley and haveoccasionally raided into urkana occupied lands near the south-western lake shore.Te Cushitic-speaking Dassanech live in the Omo delta, extending south into theIleret area o Kenya, and into the northern parts o Sibiloi National Park. Te El Molo,who live on El Molo Bay, north o Loiyangalani, are the lakes only hunters whotraditionally shed and hunted crocodile and hippo. Although Cushitic, they haveintegrated over the years with the Nilo-Saharan speaking Samburu.

Te Gabbra are Oromo-speaking camel pastoralists who range over the northern areaso Kenya between the lake, the Ethiopian border, and Marsabit in the east. Te Rendilleare camel nomads who range the Kaisut desert south-east o the lake, south o theGabbra traditional range, extending south towards Isiolo.

Livestock in the dry lands include cattle, sheep, goats, camels and donkeys, withcattle restricted to areas with reshwater sources, and with camels ranging into themost arid areas.

According to the Omo-Gibe Master Plan, the Omo Basins Ethiopian populationnumbered 8.78m. in 1994 and was orecast to more than double to over 19m.by 2024(Woodroo e et al., 1996).9 Te Lower Omo population was reported to number173,542 people in 2010, o whom 82,000 (roughly hal ) are directly dependent onthe Omo River (SOGREAH, 2010, p.65).

7 Information from David Turton, African Studies Centre, University of Oxford.8 For more detailed information on recent changes in the livelihood strategies of the Dassanech and

others living in the Lower Omo and Omo delta area, see Claudia Carr, 2012.

9 Population data are tabulated in Avery, S.T., 2012 - Table 15, p.79.


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According to Kenyas 2009 population census, around 1m. people were thenliving within Kenyas urkana, Samburu and Marsabit Administrative Districtssurrounding the lake (Avery, S. ., 2012, able 17, p.80). Te western lakeshorepopulation density is six-times that o the eastern shores (ibid., Figure 21, p.83).Roughly 200,000 people live within reach o the eastern and western shoreso the lake, o which about 90,000 are along or close to the shore (estimatesbased on Kenyas 2009 population census (Avery, S. ., 2012, p.81). Te lakeshorepopulation is small, with 56,000 estimated to be living on or close to the westernshore, and 35,000 on or close to the eastern shore (ibid.).

Te published livestock population o urkana District has uctuated widelysince the late 1970s, but it has not increased overall, being limited by orageavailability (Avery, 2012, Figure 27, p.101). Te human population, on the

other hand, has increased dramatically, resulting in a steep decline in per-capitalivestock wealth and a growing dependence on ood aid. Food aid can accountor up to 75 per cent o average household ood intake around the lake (Brewin,

2009), and up to 50 per cent in the Lower Omo (SOGREAH, 2010, p.46).

The lakes reducing drainage areaLake urkana was ormed within the East A rican Rif System that extends over3,000 kilometres rom the Red Sea and Gul o Aden, through Ethiopia, Kenya

and anzania, to Southern Mozambique (Dunkley et al., 1993). Te Rif Valleyormed 20m. years ago, and Lake urkana was in existence 4.2m. years ago. Amajor lacustrine phase at that time was ollowed by regression, and 3.9m. yearsago the Omo River owed through to the Indian Ocean, until urther rifing ledto the ormation o a closed lake basin (Ochieng et al., 1988).

With a sur ace area o 7,000 square kilometres, todays Lake urkana is Kenyaslargest lake, A ricas ourth largest, and the worlds largest desert lake. Its lengthis 257 kilometres, its average width 31 kilometres and its average depth 31metres. It reaches its maximum depth o 114 metres near its southern end. But10,000 years ago there was a more humid climate and a mega lake existed,with a water level almost 100 metres higher than it is today (Avery, S. ., 2012,p.72-73). Its sur ace area was ve-times larger and the shore extended 100kilometres north into what is now Ethiopia (ibid., Figure 16, p.75). About 150kilometres northwest o the present delta, the lake was able to relieve pressureby spilling over a sill into the drainage basin o the Nile, thus preventing the lake

rom rising any higher.

Te lakes ancient shoreline is clearly visible today in the orm o conspicuous

wave-cut plat orms (Figure 3), and remnant beaches are ound at the ormer


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Nile spill elevation. Remnant reshwater mollusc beds can still be ound at thiselevation. In the south, the ancient shoreline is 80 metres above the present-daywater level, 20 metres lower than in the north, this difference being attributable tosubsequent tilting o the land sur ace (Garcin et al., 2012).

Figure 3: South Island, showing the ancient shoreline

Te last time there was uvial connection between Lake urkana and the Nilebasin was about 6,500 years ago. It is probable that there then occurred a majorclimatic transition (Garcin et al. 2012), as a result o which the region becamemore arid, a period during which all regional lake levels dropped. In responseto the declining rain all, crop agricultural activity declined and pastoralismemerged as the most success ul arid-zone livelihood, an adjustment that occurredthroughout East A rica. In recent years, the pastoral livelihood balance hasbeen upset by human-induced changes. Tese include a burgeoning population,sustained by external support mechanisms in health and ood, constraints onmobility imposed by international borders, and contraints due to resourcecompetition and the conversion o pastoral rangelands to other purposes.

Contemporary lake water levels were rst compiled by the geomorphologist KarlButzer (1971). Butzers observations were updated by Hopson et al. (1982) andKallqvist et al. (1988). In my A rican Studies Centre report (2012), I extended theseobservations with data rom the Kenyan Marine and Fisheries Research Institute

or 1988-2008, and satellite radar altimeter data rom the US Department oAgricultures Foreign Agricultural Service or 1992 to the present (Avery, S. , 2012,p.152 and p.156). Since its contemporary high water level in 1896, the lake declined20 metres to its lowest levels in the 1940s and 1950s, be ore rising sharply in the1961 oods, then dropping to its lowest levels again in 1988. Te lake level rose to ahigh in 1999, and today is still above the lowest level (ibid., Figure 57, p.152).


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Te mega urkana catchment area once covered 203,080 square kilometresand incorporated many lake basins that have since disconnected uvially,becoming themselves closed basins (ibid., p.106). Tese include the EthiopianRif Valley lake chain and Kenyas Suguta Valley, Lake Baringo, and LakeBogoria. Even in contemporary times (between 1908 and 1920) SandersonsGul , now a large clay mudat at the northwestern end o Lake urkana,disconnected rom the main lake (Hopson et al., 1982), and the lakes directdrainage area thereby reduced rom 148,000 to 130,860 square kilometres(Avery, S. ., 2012, p.106). odays catchment remains a major trans-boundarybasin, split roughly equally between Ethiopia and Kenya, but also encroachinginto South Sudan rom southern Ethiopia, and beyond Mount Elgon in westernKenya into Uganda (ibid., Figure 31, p.109).

Water quality and healthLake urkana, which lies within Kenyas most arid zone, receives roughly 10times less annual rain all, as recorded at Lodwar10 on the urkwel River, than thehighland catchment area o the Omo.11 Tis contrast can be described in terms oannual net evaporation (the balance between potential evaporation and rain all).Te Ethiopian highlands experience a negative net evaporation o up to 2,000 mm(i.e. afer evaporation, there is a net 2,000 mm o water available annually throughrain all) while Lake urkana experiences a positive net evaporation o roughly the

same amount, which means it has the potential to lose 2,000 mm more sur acewater through evaporation than it gains through rain all. In terms o water balance(the balance between inputs into, and outputs rom, a drainage system), there ore,there is a potential difference o up to 4,000 mm between the moist upperhighlands and the arid lowlands.

Since the lake is a closed basin, its water level represents the balance betweeninow and evaporation. Every year it loses over 10 times more sur ace waterthrough evaporation than it receives through rain all, a volume equivalent tothe entire annual Omo River inow. Water is retained in the lake or only about11.5 years, leaving behind minerals carried into the lake by rivers. Hence the lakeis semi-saline, but with a salinity level much less than it might be. Te presentsalinity level is equivalent to a lake only 600 years old, whereas the lake has beenclosed or more than ten-times that period. Tis means that salts are being

10 The Lodwar rainfall chart dates from 1921 and, since that time, the average annual rainfall hasincreased overall, with the driest periods recorded in the 1930s and 1990s see Avery, S.T.,2012, Figure 42, p.128

11 There is also less variation in rainfall, from year to year, in the highlands see Avery, S.T., 2012,Figure 33, p.119


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removed at a considerable rate through deposition and chemical processes (Hopsonet al., 1982; and re erences in Avery, S. ., 2012, p.162).

Ever since the lake became a closed basin, its waters have become progressivelymore saline through the relentless evaporation. Although people and livestock drinkthe lake water today, they do so only in the absence o alternative potable sources.Around the lake, there are many scattered springs, and numerous wells, many beingdug in seasonal watercourses which are replenished by periodic rain all (Avery, S. .,2012, Section 16, p.177-188). People will use these in pre erence to lake water, whenthey can. In addition, the reshwater inow rom the Omo dilutes the lakes northernwaters, thereby improving quality locally, but lake salinity increases southwards.

Water chemistry data or Lake urkana show this is a sodium carbonate lake

with a high pH level, high in dissolved salts (total dissolved solids) and with anionic composition typical o East A rican saline lakes.12 otal ion levels in the lakeare ar in excess o the limits set by the WHOs potable water quality standards(WHO, 1984). Te individual ion levels are also high, with the exception ocalcium, magnesium, iron, nitrate, and phosphate. Tis is attributable to salt lossesoccurring through sediment / water interactions (Hopson et al, 1982). Notably, thecalcium concentration has halved in the lake through its use as an essential skeletalnutrient, and its subsequent deposition to the lake bed as calcite. 13 Other nutrientscommonly used by plankton include iron, silica, phosphorus and nitrogen, withnitrogen being this lakes limiting nutrient inso ar as productivity is concerned. Ionconcentrations in the Omo, however, are well within the WHO limits (ibid., Hopsonet al. 1982). I we compare the lakes water chemistry with Kenyas quality standards

or community water supply, we nd that the total dissolved solids concentration(salinity) is double the guide value (MoWD, 1992a; Avery, S. ., 2012, able 44,p.172). For livestock, the lakes salinity level is just within the allowable limit but itsuoride concentration is more than double the limit (ibid., able 46, p.174). Camelsand small stock are watered rom the lake on a permanent basis, but cattle areknown to take ill effect (MoLD, 1991; Avery, S. ., 2012, p.174).

Te lakes uoride concentration ar exceeds acceptable health limits or bothhumans and livestock (Avery, S. ., 2012, p.172-174). Varying degrees o uorosisoccur. Mottling o teeth due to uoride in water is not unusual in Kenya, but

12 See Walsh and Dodson, 1969; Hopson et al, 1982; Avery, S.T., 2012, p.171. An ion is an atom ormolecule in which the total number of electrons is not equal to the total number of protons, givingthe atom a net positive or negative electrical discharge (Wikipedia).

13 See Avery, S.T., 2012, Table 42, p.171 for tabulated calcium levels. Note that calcite (calciumcarbonate, CaCO 3) is the primary constituent of the skeletal structures, scales and teeth of aquaticorganisms and animals (Wikipedia) such as plankton, algae, sh, crocodiles, etc. Upon death, thecalcite sinks to the lakebed.


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around Lake urkana there are people suffering rom crippling skeletal uorosis.One old man interviewed in January 2012 denied that dependance on lake watercaused his disease. Instead, he regarded his skeletal de ormation as a curse and saidthat he pre erred to drink lake water because it tasted better and because one doesnot need to add salt to ood (ibid, p.173). Even though international NGOs wereinstalling a new water supply nearby rom a potable protected spring, this old manclaimed he was ignorant o the consequences o high uoride in his drinking water.

Long-term reductions in Omo River inow into the lake will exacerbate the alreadysignicant health risks associated with the drinking o lake water by lakesidecommunities. Added to these risks will be the potential or chemical pollutionstemming rom commercial agricultural activity in the Lower Omo, and the waterquality effects o algal blooms (a consequence o excess nutrients coming rom

agricultural run-off). Algal blooms are an explosive growth that can clog the waterwith dense toxic algae harm ul to sh. Te blooms block light penetration and, ondie-off, exert a biological oxygen demand, thereby depleting oxygen resources.

Finally, and according to Kenyas Standards or Irrigation Water (EMCA, 2006), thelakes salinity level is already double the limit suitable or irrigation (Avery, S. ., 2012,

able 48, p.175).

FisheriesLake urkana was the last o the worlds large lakes to have its underwatertopography (bathymetry) mapped in detail. Tis was undertaken by the Lakeurkana Project (1972-75), a major three-year scientic expedition run andunded by the Fisheries Department o Kenya and the UK Ministry o Overseas

Development (Hopson et al., 1982). Te aims o the project were to complete asheries inventory, to study sheries ecology and numbers and the prospects orcommercial sheries, and to prepare a bathymetric chart. Sixteen scientists weremobilised and a 50 f research vessel was built and imported rom Scotland, anextraordinary logistical undertaking. Te expeditions work established a sheriesecology baseline. Forty eight species o sh were identied, 12 o which wereriverine and conned to the Omo delta. Further studies were undertaken rom1985-88 by the Norwegian Institute or Water Research and the Kenya Marineand Fisheries Research Institute (Kallqvist et al., 1988). In recent years, the list hasgrown to include 60 sh species (Ojwang et al., 2007).

Te lakes aquatic ecology has evolved directly rom its ormer Nile uvialconnection. Te lakes sheries are thus mainly Nilotic, but with some endemicspecies. Interestingly, similar sh species occur right across northern A rica to the

Gambia (Hopson et al.,1982). Hopson reported that the sh population was well


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adapted to the environmental conditions, hydrology being all-important, andthat Breeding activityreached a peak during the Omo ood season in nearlyall species.

In a classic paper, alling and alling (1965), classied A rican lakes intothree classes according to their ionic content: low (Class I), higher (Class II)and saline (Class III). 14 Lake urkana is amongst the most saline in Class II,but still hosting varied sh resources, although with less diversity than otherA rican Great Lakes (Muska et al., 2012). With the exception o Mormyrids(electro-sensory sh), the sh were apparently unaffected by the transition

rom resh to semi-saline conditions (Hopson et al., 1982). Crocodile Lake onCentral Island alls within Class III (saline), but in spite o this, there are stillpopulations o our sh species also ound within the adjacent open lake. With

2,440 parts per million (ppm) o dissolved salts, Lake urkana is not yet trulysaline but it is not ar off.15

14 See Avery, S.T., 2012, Table 40, p.168.15 A truly saline lake contains 3,000 ppm of dissolved salts (Kolding, 1992, p.27, citing Williams,

1981). See Avery, S.T., 2012, Table 43, p.172 for the USGS salinity classications.

Figure 4: Fishing community on North Island

P h o t o : P a t r i c k A v e r y


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27/6421


Water temperatureWater temperature remains constantly warm throughout the year in the openlake, with slightly cooler waters at depth. Te lakes warmth is one o the maindrivers o its high productivity (Kolding, 1992, p.31). In the shallow enclosed oodplains areas such as Fergusons Gul , heating up o the waters will occur. Tereis also slight warming o the shallower northern waters, with a consequent smalltemperature gradient along the length o the lake.20

Incoming river oodsTe most pro ound seasonal changes in the lake arise during the annual ooding,which peaks in the period August to October and the principal source o which isthe Omo. Te upstream ooding o the Omo, the seasonal inundation o offstreamareas and the runoff there rom capture valuable organic matter and nutrients,

which are carried into the lake. Nitrogen, one o the two most important actorslimiting sheries production (the other being light), is also transported intothe lake through the Omo waters (Hopson et al., 1982). Te ood inuxes alsostimulate the migration o spawning sh into the Omo. Within the main lake, sh breeding tends to be greatest during ood periods. Tisis due to the sediment-rich waters, which extend south right through the centralsector o the lake. Te oods dilute the lake water and lower the salinity levels innorthern parts in particular. Te sediment plume reduces visibility and sh tend tomove to the lake sur ace and to the shore, and the reduced light penetration affectsproduction o organisms that depend on photosynthesis. Te inux o nutrientsduring the ood season initiates changes in the algal population, and the marginso the lake inundate (ibid.).

Lake levelsTe lake level rises are typically up to 300 mm/month, starting rom July, andin at areas o the lake, the inundated margins such as at Fergusons Gul (onthe western shore near Kalokol) can extend many hundreds o metres. Wheninundated, the shoreline terrestrial vegetation provides a re uge habitat oryoung,

recently hatched sh. I the shoreline areas were previously heavily grazed,this will reduce the potential re uge habitat and thus affects potential breedingsuccess. On the other hand, the presence o livestock adds nutrients. Te effecto nutrient load on chlorophyll production is very pronounced in northernparts o the lake (Hopson et al, 1982). Chlorophyll levels are indicative o theabundance o phytoplankton.

20 This amounted to 3.5 Centigrade in January 2012, from 26 in the south to 29.5 in the north(Avery, S.T., 2012, p.165, Fig 69, p.166). Since records began in 1960, the lake water temperaturehas warmed slightly, though not noticeably since 1990 (Avery, S.T., 2012, Fig 39, p. 125).


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Te inundation o littoral zones through oods in various A rican lakes has beenshown to result in a boom in sh populations, ofen short-lived (Kolding, 1992,p.32). Falling lake levels between 1972 and the late 1980s reduced biomass andresulted in a 70 per cent reduction in the endemic zooplankton-based open-waterpelagic sh communities in the lake. Tese sh communities are shorter-lived andunstable. Kolding reported that the sh population had undergone unpredictableand drastic trans ormation in the past decade (ibid.).

Invasive speciesProsopis juliora, an aggressive invasive plant species which over-runs pastures, wasintroduced to the Lodwar area west o Lake urkana by an NGO to green the desert(Avery, S. ., 2012, p.96). Indigenous to Mexico, it was introduced to the A ar regiono Ethiopia in the 1970s, and reached Kenya in the 1980s. It is choking Fergusons

Gul and obstructing access to the lake by shermen. It is displacing indigenous vegetation rom the banks o the urkwel River and delta, as noticed between 2001and 2008 (ibid.). It thrives in arid areas and is almost impossible to eradicate. In viewo this, efforts are being made to utilise it as a resource - or example as uel.

In summary, the production potential o the lakes sheries is signicantly affected byuctuations in river discharge. Shallow littoral areas, inundated during seasonal risesin lake level, are likely to be particularly important (Kallqvist et al., 1988; Kolding,1992). Tere is exceptionally high photosynthetic activity in this lake and the effecto the nutrient load rom the Omo on chlorophyll production is very pronounced inits northern areas. Primary production rates or algae in Lake urkana were lowerthan in Lake Victoria, but higher than Lake anganyika, and production rates inFergusons Gul were some o the highest recorded (Kallqvist et al., 1988). Because othe importance o uctuation in river discharge and lake level on the ecology o thelake, continuous monitoring should be undertaken (ibid.; Kolding, 1992). Finally,developments in the catchment area affecting discharge o water to the lake, are likelyto have serious effects on the lake ecosystem (Kallqvist et al., 1988).

Lake urkana was once unique amongst A rican lakes in lacking a substantial

indigenous shery (Bayley, 1982). Commercial shing commenced around 1950(Kolding, 1992, p.28). Since the 1960s, however, increasing numbers o pastoralistsliving around the lake and in its delta area have taken to shing to alleviate amineand destitution. Amongst pastoralists, sher olk are seen as poor people withoutlivestock. In 2010, an AFDB study (Mbogo, 2010) reported 8,160 shermen, withnumbers increasing. Fishing practices were described as artisanal, with 60 per cento the 6,900 boats being traditional raf boats (ngatedie). Te marketing o sh ishampered by poor or absent transport in rastructure, the long distance to markets,and the absence o storage acilities - local people rely on sun-drying and salting osh or storage. In the 1980s a sh processing plant was built at Kalokol in an ill-


29/6423


researched albeit well-intentioned donor initiative. Te plant never opened and wasdescribed as a welcome object or ridicule rom aid sceptics ever since (NORAD,2008).

Annual total sh catch records have reached 9,500 tonnes/year, in recent years(Avery, S. ., 2012, Fig.84, p.200), well below the estimated sustainable production o15,000 to 30,000 tonnes/year (Kallqvist et al., 1988). Whilst Lake urkanas annualsh catch is the second highest in Kenya (afer Lake Victoria), in proportion tolake area the catch is tiny. Te area o Lake Victoria shed by Kenyan shermen isonly 4,260 square kilometres, slightly more than hal the 7,000 square kilometres oLake urkana, yet the sh catch is typically 12-times, and up to 50-times higher.21 Nonetheless, even at present production levels, Lake urkanas sheries provide a valuable protein source and an alternative livelihood in a vulnerable area with ood

security challenges. Te destruction o the urkana sheries would there ore have very serious socio-economic consequences.

National parksIn 1997, the Lake urkana National Parks were added to UNESCOs World HeritageList as a site o outstanding universal value. Tis World Heritage site comprisesSibiloi National Park and the two island national parks, Central Island and SouthIsland (Figure 2). Sibiloi National Park is the only Kenyan national park created or

archaeological reasons. Te lakes third island, North Island, is not a national park,and hence is not within the protected area. Figure 5 shows South Island rom southo Loiyangalani and the distinct colouration o the lake, caused by its dominant blue-green algae, which has earned it the popular name the Jade Sea.

Te crater lakes o Central Island were ormerly submerged and have progressivelyemerged as the main lake level declined (Hopson et al., 1982). Flamingo Lakebecame isolated in the late 1890s, ollowed by Crocodile and ilapia Lakes in 1902and 1972 respectively. Lake urkana once boasted the highest concentration o crocodiles in the world and Crocodile Lake was a world renowned breedingplace.22 Although isolated, the lakes are replenished mainly through undergroundpercolation rom the main lake, and thus their individual lake levels ollow themain lake level. However, their salinity levels do differ, being mainly a unction

21 Based on data from 2003-2004, see Avery, S.T., 2012, Table 56, p.199. The Lake Victoria shcatch in Kenyan waters is over 100,000 tonnes annually.

22 A eld expedition in early 2012 reported very few crocodiles. Nests were witnessed being raidedfor eggs by shermen and crocodiles were noted being ensnared and drowning in nets. It was alsosuspected that they were being shot , as large animals pose a threat to shermen (Avery, Patrick,2012; Avery S.T. 2012).


30/6424

o the time elapsed since they separated rom the main lake, and also a unctiono exposure to winds. Tus Flamingo Lake, the longest isolated, is the most

saline, with an electrical conductivity reading over 10-times that o the open lake(Avery, S. ., 2012, able 39 and Fig.71, p.165-166). I the open lake level dropssignicantly, these crater lakes could dry up altogether.

In 2011, the UNESCO World Heritage Committee expressed concerns about thecumulative impacts o hydropower dams and large-scale irrigation in the OmoValley on the Lake urkana National Parks. Te Committee urged the Ethiopiangovernment to halt construction o the Gibe III dam, pending reports romboth Ethiopia and Kenya (WHC, 2011). Te Ethiopian response dismissed the

Committees concerns out o hand, describing them as one-sided and highlybiased ( urton, 2012c). In March 2012, a joint monitoring mission rom theWorld Heritage Centre and the IUCN visited the Lake urkana World HeritageSite at the invitation o the Kenyan Government (WHC, 2012a; Avery, S. ., 2012,p.44).23 In its report to the World Heritage Committee, the WHC / IUCN teamrecommended that Lake urkana National Parks be added to the List o WorldHeritage in Danger. But at its two subsequent meetings the Committee has ailedto act on this recommendation (WHC, 2012b and 2013a and 2013b).

23 The Committee had requested a similar invitation from Ethiopia but none had been forthcoming.

Figure 5: The Jade Sea, with South Island in the background


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Irrigation water demandin the Omo Basin

In 1996, a development Master Plan was produced or the Omo-Gibe Basin(Woodroo e et al., 1996). Te erms o Re erence were prepared by the EthiopianDevelopment Studies Authority (EVDSA, 1991) and approved by the A ricanDevelopment Bank (AFDB). Te aim was to plan the basins multi-sectoraldevelopment strategy, and prepare implementable sustainable projects, mainlyagricultural, to exploit the basins natural resources (ibid.). Tis included exploitingthe hydropower and irrigation potential o the basin, and identi ying schemesthat would depend on major dams to control the Omo river water. Tese damswould raise the river water level to create a head o water needed or hydropowergeneration. Te dams would impound sufficient water to thereafer enable reliablecontrolled releases through the turbines throughout the year. In so doing, the damswould alter the entire river hydrology. Te dams would control oods, and uplif therivers low ows, thereby reversing the declining low ows that are a consequence

o increasing smallholder irrigation abstraction. Te uplifed low ows, and theincreased low ow reliability, would also enable year-round commercial irrigatedagriculture downstream rom the dams.

A major ailing o the Master Plan was the omission o any study o thetransboundary impacts o the proposed basin developments, particularly on Lake

urkana. Tis was in spite o its prediction that 32 per cent o the Omo waterswould be abstracted by the year 2024. Te consultants acknowledged there wouldbe detrimental effects on Lake urkanas sheries, but they appeared to diminish the

signicance o these effects by stating that the sheries were declining anyway due toover-exploitation (Avery, S. ., 2012, p.25). Te Master Plan did however recommenda bilateral agreement between Ethiopia and Kenya be ore either country changes thenatural ow o the river through hydropower or large-scale irrigation development(ibid.). Tis recommendation was un ortunately disregarded.

Te World Bank has also long been encouraging Ethiopia to reduce its oodsecurity challenges by utilising the countrys abundant water resources or irrigatedagriculture in its semi-arid lowlands. In a Concept Paper published in 2004, theBank justied development impacts on Lake urkana on the grounds that thereis no signicant use o Lake urkanas waters and that the Kenya Government can


32/6426

benet rom Ethiopias projects. Te paper concluded that, whilst the Omo Basinwas an early candidate or development, there was also a need or research into thesocial problems that might arise as a result o population displacement (World Bank2004a; Avery, S. ., 2012, p.26-27). Whereas no such social studies have materialised,ecological consequences did not even warrant a research recommendation.

Potential irrigated areaTe Master Plan estimated that 31,780 hectares in the Lower Omo were suitable orsmall-scale irrigation and 54,670 hectares or large to medium-scale irrigation,24 making a total irrigable area o 86,450 hectares.25 Much bigger estimates havebeen made by other organisations, including 348,000 hectares (World Bank,2004a) and 445,000 hectares (FAO, 1997). Te hydrological impact o potentialirrigation development on anything like this scale is nowhere considered in theimpact assessments or the Gibe III hydropower dam. Tis is surprising since, aspointed out in the Master Plan, it was precisely the regulated river ow created byhydropower dams that would make large-scale, year round commercial irrigationschemes possible in the Lower Omo. And yet, in the ew sentences devoted tocommercial plantations in the Gibe III project documents, it is assumed, or thesake o argument, that these will cover no more than 5,000 hectares and that theywill almost certainly be conned to the delta plain. Cotton was described as themost likely crop and sugar the least likely because o its high in rastructural costs

(Agriconsulting et al., 2009, p.83-84).

Nevertheless, it was announced in January 2011 that the Ethiopian SugarCorporation was in the process o implementing a plan to create 150,000 hectares oirrigated plantations in the Lower Omo, a gure that was later increased to 175,000hectares.26 Te greater part o this area (135,285 hectares) was to be excised romthe Omo National Park, the Mago National Park and the ama Wildli e Reserve(EWCA, 2011)27 something that had not been envisaged in the Master Plan. Tisscheme, known as the Omo-Kuraz Sugar Development Project, will create a hugepotential water demand rom the Omo River. Te three sugar blocks making upKuraz are shown in Figure 6, along with the proposed irrigation conveyance canals

24 The Master Plan adopted the criteria used by the Ethiopian Government to classify irrigationschemes, according to area cultivated, as follows: small-scale: < 200 ha; medium-scale: 200-3,000ha; and large-scale: >3,000 ha (Woodroofe et al., 1996; Avery, S.T., 2012, Section 4.12, p.54).

25 The Master Plans small-scale irrigation areas are listed in Avery, S.T., 2012, Table 7, p.56. TheMaster Plans medium and large-scale areas are located as shown in Avery, S.T., 2012, Fig.8, p.55with scheme details tabulated in Tables 8 and 9, p.58.

26 According to local press reports, the total area allocated to the Sugar Corporation in the lower Omowas 245,000 hectares, but not all of this was considered suitable for sugar production.

27 The EWCA excised areas and maps are included in Avery, S.T., 2012, p.37-39.


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leading to the lake (shown as dashed blue lines). Te Omo and Mago NationalParks are shown shaded green, and the ama Wildli e Reserve is the areabetween the two parks.

O m o

R i v e rOmo National Park Mago National Park

Area of overlap betweenSugar block 1 and Omo NP



Sugar block 1Area 82,600 ha



Sugar block

Award argriculturalInvestment as of March 2011

National Park

Land marked by G of Eas available for agriculturalInvestment

Irrigation canal

Figure 6:Planned irrigation

development inthe Lower Omo,2011.

(Source: Human Rights Watch, 2012)

Jinka

Hanna


34/6428

Also shown on this map are areas south o the sugar blocks which were knownto have been leased to private investors and land that had been identied bythe Ethiopian Government as available or agricultural investment. Puttingtogether both government and private land investment plans in the Lower Omo,the Oakland Institute (2011) reported that the area potentially totalled 445,501hectares, including the 245,000 hectares allocated to the Sugar Corporation. 28 Flintan (2011) presented a map and table o agricultural investment areas inthe Lower Omo totalling 180,675 hectares.29 Tese data, which came rom theEthiopian Embassy in Stockholm and did not include the sugar plantation areas,were consistent with the Oakland Institute data. Finally, in 2012, the KenyaGovernment announced 10,000 hectares o irrigation development near thenorthwestern shore o Lake urkana, at odenyang (Figure 2). Te water sourceand water demand have not been reported but the Omo is an obvious potentialsource. In addition, massive underground aqui er nds were recently announced

in urkana, which have raised expectations about the possible uture use o thiswater or irrigation (Radar echnologies International, 2013). 30

able 1 represents a conservative estimate o the potential extent o medium andlarge-scale irrigation in the Lower Omo, based principally on the Master Planpredictions and known plans or the Kuraz Sugar project. Te Kuraz plantationpotential totalled 161,285 hectares, 31 and the total lower basin potentialirrigation (including 10,000 hectares at odenyang) amounted to 208,655

28 The tabulation of agricultural area allocations is reproduced in Avery, S.T., 2012, p.52.29 The map of South Omo agricultural investment areas is reproduced in Avery, S.T., 2012, p.60.30 The resulting media euphoria needs to be put into perspective, as explained in the nal section of

this paper.31 This gure is the summation of 135,285 ha excised from national parks/reserves and 26,000 ha

south of the Omo National Park (Avery, S.T., 2012, p.58). The gures are based on reported soilstudies of suitability for irrigation (ibid.). Note that there are unusual characteristics associatedwith the lower Omo soils. In the case of the abandoned Ethio-Korean scheme near Omerate,sink holes developed with irrigation or heavy rainfall (SOGREAH, 2010, p.31). These are youngsoils, as this area was formerly the lake bed (ibid.). The author has frequently encountered thesedispersive soils in the Rift Valley, on one occasion losing an entire Land Rover in a large sinkhole. The Sugar Corporation has mentioned the potential sugar plantation area being as much as175,000 ha, but as supporting soil studies have not been released, I did not adopt this gure forthese calculations.

Turkwel delta, Lake Turkana



35/6429


hectares.32 o put the Lower Omo project scale into a regional perspective, theKuraz sugar scheme alone covers an area almost equivalent to the entire irrigatedarea o Kenya, estimated to be 165,800 hectares in 2011 (JICA/NK, 2012).

32 When viewing published data on agricultural development areas, a distinction needs to be madebetween irrigated agriculture, and land used for rain-fed or other non-water consumptiveagricultural purposes. This distinction is not always made clear in publications.

Name of Farm Area(5) Existing Potential Potential Excised Kuraz 2012 Irrigated Before After Area (2) Sugar Potential Area Soil Soil Potential Irrigable (Ethio- Survey Survey (4) Area(5) Korean Farm)(3) (M.Plan) (M.Plan) (EWCA) (ESDC)

ha ha ha ha ha ha

Upper Omo (M.Plan)(1) Bako-Gibe - - 400 - - 400Kulit-Darge - - 1,600 - - 1,600Walga-Kulit - - 5,300 - - 5,300

Lower Omo Excision(2) NP / Tama Excisions - - - 135,285 135,285 135,285

Lower Omo (M.Plan)Omo Higher Farm - 10,000 8,700 - - 8,700Dipa Hayk - 5,000 5,880 - - 5,880Omo Rate (Ethio-Korean)(3) 1,400 - - - - 1,400Omo Rate West - 10,000 4,020 - - 4,020South of Mago - 8,000 8,000 - - 8,000South of Omo NP (Kuraz) - 26,000 26,000 - 26,000 26,000Nargi Ridge - 8,000 2,070 - - 2,070

Kenya Basin - - - - - -Todenyang - - - - - 10,000

Total 1,400 67,000 54,670 135,285 161,285 208,655

Note(1): Woodroofe et al, Vol. XI, F2, p53, 1996Note(2): EWCA (2011) Section 3.10, p58 (Note: NP=National Park).

Note(3)

: Woodroofe et al (1996) (Ethio-Korean Scheme reported abandoned in 1991).Note(4): ESDC = Ethiopia Sugar Development Corporation.Note(5): Location of Schemes see Avery, S.T., 2012, Fig.9, p55, and Fig.10, p59

Table 1: Potential medium and large-scale irrigation areas in the Omo Basin


36/6430

Available in ormation on the actual and potential extent o small-scale irrigationin the Omo Basin is sketchy and contradictory. In 1996, the Master Planestimated that 8,751 hectares were under small-holder irrigation, with thepotential or this to increase to 31,782 hectares. 33 In 2009, the Gibe III Economicand Social Impact Assessment (ESIA) reported that existing and potentialsmall-scale irrigation areas amounted to 667 hectares, and 10,100 hectares,respectively (CESI and Mid-Day, 2009). Te existing gure seems low, andthe potential is a raction compared to the Master Plan estimate. In 2010, theconsultants SOGREAH used satellite imagery to assess the area o ood-retreatagriculture in our weredas (districts) in the Lower Omo (SOGREAH, 2010).Tey estimated about 4,000 to 5,000 hectares under ood-retreat cultivationin the Dassanech wereda, with small-scale cropping limited to riverbankselsewhere (ibid., p.37), and with 82,000 people depending directly on the river

(47 per cent o the areas population) (ibid., p.34 and 65).

Tey also estimatedthat an additional 15,000 people benetted rom the seasonal inundation andrejuvenation o dry-season grazing lands (ibid., p.34). 34 A total population o100,000 could thus be affected (ibid., p.37). It is essential to consolidate theseestimates and veri y the total area under small-scale irrigation today, in orderaccurately to assess both irrigation water demand and the potential impacts oirrigation abstraction on available water downstream.

Te Gibe III project documents predicted that the people o the Lower Omowould experience enhanced ood security as a result o Gibe IIIs regulatedow sequence, with people downstream being encouraged to move away

rom risky rain- ed agriculture to more secure irrigated agriculture(Agriconsulting, 2009). It was also suggested that major benets would beinduced by the regulation o river ow in the downstream Lower Omo valleyin terms o permanent availability o water with stable water levels allowing

or development o commercial irrigated agriculture (Salini Costruttori et al.,2009b). Te amount o water that would have to be abstracted rom the Omoto provide these benets was described as negligible, compared to the annualows. My own study on behal o the AFDB, however, did not conrm this

prediction and instead raised the spectre o Lake urkana reduced to two smalldisconnected lakes a potential A rican Aral Sea in the making.35

33 The Master Plan tabulation of small-scale irrigation areas is reproduced in Avery, S.T., 2012 seeTable 7, p.56.

34 A tabulation of the SOGREAH ood-recession agriculture data is included in Avery, S.T., 2012 -Table 3, p.51.

35 See Avery, S.T, 2012, p.33; Avery, Patrick, 2012. The Aral Sea, Central Asias most infamous man-made environmental disaster, was once one of the four largest lakes in the world. It steadily shrunkafter rivers feeding it were diverted in the 1960s by Soviet irrigation projects (Wikipedia). By

2007, the lake was 10 per cent its original size (ibid.). Salinity levels rose, shing ceased altogether,and salts blown by winds from the dried lake bed are destroying pastures (UNEP, 2008).


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Irrigation system efcienciesTe overall efficiency o an irrigation scheme determines the gross waterabstraction required rom the river. It is dependant not only on the irrigation

methodology adopted, but also on competent scheme design and construction,and the efficiency o operation and maintenance. As ar as Lake urkana isconcerned, the less efficient the irrigation scheme, the more resh water thelake will be deprived o , although some o the water will return to the river,either through percolation, or through drainage canals. In any event, substantialwater losses are inevitable and irrigation methodology will be a critical actorin minimising impacts on Lake urkana. Un ortunately, however, we do notknow what irrigation methodologies will be used in the Lower Omo because

easibility studies have not been released. In what ollows, there ore, typicalschemes and efficiency values are outlined, using indicative gures published inFAO documents (FAO, 2000; and 2009).

Irrigation water is abstracted rom the river and conveyed to the scheme,either by open canal, or by pipeline. Pipelines are used or pumped water orwhere topography is not suited to gravity canals. Earthen canals are suitable inimpermeable soils, but canals passing through permeable soils should be lined.According to FAOs indicative values, the conveyance efficiency o a schemecan vary hugely, rom 60 per cent or a long canal in sandy soil to 95 per cent ora lined canal.

Once the water has reached the crop area, one or more o the ollowing waterapplication methods may be used. In sur ace irrigation, the water is appliedthrough simple gravity ooding o the crop area through urrows, withirrigation water soaking into the crop root zone. In sprinkler irrigation, thewater is mechanically sprayed onto the crop as a jet or spray, using pressure

ed sprinklers or centre pivot36 systems. Tis is more sophisticated, as itrequires hydromechanical systems to pressurise and convey the water, buthigh evaporation losses can result during this application process. In smallerintensive cultivation systems, and where water is scarce, water can be eddirectly to the root system. Tis drip system is more intricate and well suited tointensive horticulture, and nutrients are ofen blended with the applied water.Sur ace irrigation is the more traditional system and hence more common.According to FAOs indicative values, the application efficiency (i.e., excludinglosses due to the conveyance system) o a sur ace irrigation system is typically50 per cent. For sprinkler irrigation the gure is 55-75 per cent and or dripirrigation 80-90 per cent.

36 In centre-pivot systems, water is sprayed from a perforated pipe at the centre of a circular eld.


38/6432

Considering the overall efficiency o a scheme,37 FAO categorizes 50-60 per centoverall efficiency as good, 40 per cent as reasonable and 20-30 per cent as poor.Te Master Plan adopted 45 per cent overall efficiency or assessing irrigationwater demands in the Omo Basin (Woodroo e et al., 1996), while Kenyas NationalIrrigation Board adopted 40 per cent overall irrigation efficiency or its Hola schemeon the ana River (NIB, 2004). Te rain all and climate conditions or the Omo and

ana schemes are comparable, and both are on ood plain soils adjacent to a majorlowland river.

Irrigation water demand as a percentage of Omo owTe Lower Omo is hot, dry and windy throughout the year. 38 Irrigation designaims to avoid crop stress by ensuring that crop water evapotranspiration 39 needsare met. As evapotranspiration in the Lower Omo is on average almost 8-times therain all, the water decit to be met by irrigation is huge. o estimate this demand,it is necessary to consider the water needs o different crops and cropping patterns.For this study, two crop scenarios were chosen, both at 60 per cent 40 overallirrigation efficiency: a mixed crop scenario, requiring 0.712 litres per second perhectare (SOGREAH, 2010) and sugar cane plantations, requiring 1.115 litres persecond per hectare (FAO, 2009; 2000). 41

In able 2, the potential irrigation water requirement rom the Omo is shown, rst,

or the Kuraz sugar scheme alone (161,285 hectares), second or the remainingarea that previous studies have identied as suitable or irrigation (47,370hectares) and third or the two combined. Te water requirements are huge, asis the water saving through increasing the irrigation efficiency rom 45 to 90 percent. Te gures do not include canal conveyance water losses. Tese canals areassumed lined, with losses returnable to the river system, although a portion willbe evaporated. Te eld efficiency in the table, there ore, re ers only to lossesassociated with the irrigation application methods. In the case o sprinklers, thewater is sprayed through the air, with resulting airborne evaporation losses. Tere

37 Scheme Irrigation Efciency (overall efciency) = Conveyance Efciency x Field ApplicationEfciency (see Avery, S.T., 2012, p.62-63).

38 Typical Lower Omo climate data near the lake are as follows: Annual average temperature, 29.8C;Average wind speed 1.9 m/s; Annual average rainfall 335 mm per year; Evapotranspiration, 2,293mm per year (Avery, S.T., 2012, p.114-120).

39 Evapotranspiration is the loss of water vapour to the air through both evaporation and planttranspiration.

40 This is a relatively optimistic assumption, given that the Master Plan assumed an overall irrigationefciency of only 45 per cent see other comparisons in Avery, S.T., 2012, p.62.

41 For more details on crop water requirements see Avery, S.T., 2012, Section 4.16.3, p.63-64, alsoSection 4.16.1, p.61.


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Lower Omo: Kuraz annual irrigation @ 161,285 hectares

Percent Irrigation Total Total Gross IrrigationField Category Net Gross Irrigation Water DemandEfciency Method Irrigation Irrigation for 161,285 ha % Omo

% mm/yr mm/yr MCM/yr m3/s %

45% Poor 2,110 4,689 7,562 240 43.9%60% Furrow 2,110 3,517 5,672 180 32.9%70% Sprinkler 2,110 3,014 4,862 154 28.2%90% Drip 2,110 2,344 3,781 120 22.0%

Lower Omo: Remaining suitable area, mixed cropping @ 47,370 hectares

Percent Irrigation Total Total Gross IrrigationField Category Net Gross Irrigation Water DemandEfciency Method Irrigation Irrigation for 47,370 ha % Omo% mm/yr mm/yr MCM/yr m3/s %

45% Poor 1,347 2,992 1,418 45 8.2%60% Furrow 1,347 2,244 1,063 34 6.2%

70% Sprinkler 1,347 1,924 911 29 5.3%90% Drip 1,347 1,496 709 22 4.1%

Lower Omo: Combined 208,655 hectares (161,285 ha sugar + 47,370 ha mixed crop)

Percent Irrigation Gross Total Combined IrrigationField Category Irrigation Irrigation Irrigation Water DemandEfciency Method Water Water 208,655 ha % Omo

161,285 ha 47,370 ha

% m3/s m3/s m3/s %

45% Poor 240 45 285 52.2%60% Furrow 180 34 214 39.1%70% Sprinkler 154 29 183 33.5%90% Drip 120 22 142 26.1%

Table 2: Lower Omo irrigation potential annual water usage


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will be a small returnable component o the losses, through drainage rom theelds back into the river. Tis is not quantied here, since it is not critical in termso this water balance. But it could be critical in terms o its potential to carrychemical pollutants back into the river or into the underlying groundwater table,both o which lead to the lake. Te sugar actories will also require water, as willthe thousands o migrant workers imported to run the schemes. But, these waterdemands pale into insignicance compared to the huge irrigation crop demand.

Note that the Kuraz scheme alone will require over 30 per cent o the Omo ow as aminimum and this rises to nearer 40 per cent when the remaining area is included.Te total requirement could easily reach over 50 per cent, which in magnitude isequivalent to almost hal o the renewable sur ace water resource in the whole oKenya.42 Te potential reduction o inow to Lake urkana is there ore huge, and ar

greater than previously reported. It should also be borne in mind that any increasesin temperature with ongoing climate change will raise evaporation rates, and henceincrease crop water requirements. Climate change models orecast increases inrain all in these arid zones, but rain all is very low anyway, and the increased rain all volume is very small. Hence the long-term irrigation water demand is likely toincrease, as will evaporation losses rom the lake itsel (Avery, S. ., 2012, p.66). Tehigh evaporation associated with arid and semi-arid areas creates other challenges. Itleads naturally to much more saline soils than in humid moist areas. Soil salinisationis exacerbated by ill-designed irrigation schemes (FAO, 1976). FAO has stated: Teintroduction o irrigation is ofen considered a solution to the pressing problemso the arid and semi-arid regions. However, there are numerous examples o soilsdegraded and lost to production due to ill-conceived or poorly implementedirrigation schemes. Soil salination is an escalating global problem associated withirrigation schemes in semi-arid areas but, without access to the Lower Omo schemestudies and designs, it is not possible to comment urther on this.

We also need to consider the impact o land use changes on hydrology. Te OmoBasins Ethiopian population is orecast to reach 19m. people in the year 2024(Woodroo e et al. 1996).43 In the 30-year period since 1994, the population will

more than double. Increasing population and associated agricultural needs haveresulted in dramatic land use changes throughout Ethiopia, and in the upper andmiddle Omo Basin. People have migrated rom the degraded highlands into thelowlands, a process actively promoted by the World Bank (2004a). Vegetationis being cleared with increasing use o river water or irrigation. Te catchment

42 Kenyas average annual renewable surface water runoff is 654 m 3/s (JICA/NK, 2012 April). TheOmos average annual inow to Lake Turkana from 1993-2011 was estimated to be 555 m 3/s(Avery, S.T., 2012, Table 59, p.213).

43 The population growth is tabulated in Avery, S.T., 2012, Table 15, p.79.


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P h o t o : M a r c o B a s s i

Figure 7: Cultivation with terraces to control runoff and erosion, Ethiopian highlands

Figure 8: Flood retreat agriculture in Kara territory, Lower Omo


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rain all / runoff response is becoming aster. Tis means increased erosion risk,larger ood magnitudes, and declining low ows, resulting in an altogether lesspredictable hydrology, particularly affecting people in the lower basin (Avery, S. .,2012, p.141).

Te only way to reverse this process is through catchment management, therestoration o vegetation cover, and the complete protection o all riparian44 zones, including prohibition o human activity within these zones. Te laws

o Kenya actually orbid any cultivation o riparian zones, but en orcement iswell nigh impossible. Such areas are ofen utilised by people who have no otheroptions. Tus ood retreat agriculture is practised in the Lower Omo and in thelower reaches o Kenyas ana River. In the past, when population numbers wereinsignicant, the catchment degradation resulting rom traditional riverbankagricultural practices was insignicant, but this has ceased to be the case in recentyears. Ironically, the construction o storage dams provides the opportunity to

44 Riparian, from the Latin ripa, meaning bank, refers to the edge or margins of a river or stream,or lake or ocean.

Figure 9: Omorate, not far from the Omo delta


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control the extremes o ow that are a consequence o careless anthropogenicactivity, including riparian disturbance by commercial irrigation schemes.

Tis could be a short-term measure however, as without the en orcement oproper catchment protection, dam reservoirs rapidly ll with sediment, becomingprogressively less effective, and thus can be relatively short-lived and costlyinvestments. Te construction o storage dams is a top priority in Kenya today.Te countrys ambitious goal is to increase total irrigated area 600 per cent by 2030(NK/JICA, 2012). Climate change models predict a 20 per cent increase in Kenyasriver ows in the same period (ibid.). Te extent to which this extra water can beeffectively harnessed is another matter, as extreme ood runoff will ofen occurwhen reservoirs are already ull and spilling. It does, however, mean that greater volumes o water will reach the many regional lake sumps, offsetting (to an extent)

losses through abstraction or irrigation.

Failure to learn from experienceIt is remarkable that easibility studies, impact assessments and resettlement plans

or the Kuraz Sugar project and other irrigation schemes in the Lower Omo havenot yet been released or public discussion and scrutiny. Countless studies oriver-basin development not least in Ethiopia itsel have shown that projectsimplemented in this way are likely to have tragic unintended consequences orpeople and the environment. Furthermore, it is contrary to the recommendations

o the basins Master Plan.

Te main contractor, Salini Costruttori o Italy, was appointed without competitivebidding in a process described by the World Bank as lacking transparency(Mitchell, 2009). Tere was no detailed consideration o the impacts on Lake

urkana, and no consultation with potentially affected communities in Kenya.Te so-called Additional study on downstream impacts (Agriconsulting et al.,2009) was initiated long afer dam construction had started. Dam constructionitsel began without the prior approval o the Ethiopian Governments ownEnvironmental Protection Authority (a requirement in Ethiopian law). In short,the project has been mired in controversy since it began. Te World Bank, theA rican Development Bank and the European Investment Bank all declined togive it direct nancial support, but in July 2010 the Industrial and CommercialBank o China came orward with a loan o $450 million to cover the cost othe dams turbines, to be supplied by a Chinese company, the Dong ung ElectricCorporation. Te hydropower and irrigation schemes will drastically alter river hydrology,making dramatic changes in local livelihood practices inevitable. Te terms o

re erence or the Master Plan included provision to plan and implement the


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essential trans ormation o the socio-economic system o the local population,although what exactly was meant by essential trans ormation was not explained(EVDSA, 1991). Te Master Plan included a raf o recommendations and asocial study which cited conicts over the implementation o the Ethio-KoreanJoint Venture arm in the Lower Omo (Woodroo e et al., 1996). It noted that there were major disturbancespeople were not consultedpeople were notcompensated when land they viewed as theirs was annexed (Avery, S. .,2012, p.22). Te Ethio-Korean scheme was abandoned in 1991 (SOGREAH,2010, p.39).

Te above statements in the Master Plan are mirrored by complaints being madetoday. Over the past two years there have been persistent accusations, coming

rom campaigning organisations and others, o human rights abuses in the

Lower Omo - essentially the orced eviction o people rom their land withoutconsultation or compensation (e.g., Human Rights Watch, 2012; OaklandInstitute 2013; urton, 2012(a) and 2012 (b)). I these reports are correct, thelessons o past experience some o them documented in the Master Planitsel - are being systematically ignored in the implementation o river-basindevelopment in the Omo Valley.

Sunset over Lake Turkana from North Island



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The impact on LakeTurkana of regulated andreduced Omo ows

Water balance and ow duration curves

o assess the impact o uture developments in the Omo Basin on Lake urkana,one needs to know the current rate o lake inows rom the Omo. Records exist orthe Omos daily discharge (rate o ow) at Omorate, not ar rom the Omo delta,but only rom 1977 to 1980. In the absence o continuous river inow records, the1996 Master Plan study developed a rain all/runoff model, which simulated riverdischarges using available rain all data rom 1956 to 1994. In 2006, the Gibe III damdesign team also used a rain all/runoff model to derive ow sequences at the damsite. In my reports or the A rican Development Bank and the A rican Studies Centreat Ox ord, I developed a water balance model using an entirely different approach.

Since 1992, lake levels have been monitored using satellite radar altimeters traversingthe middle o the lake at 10-day intervals. Tese data make it possible to generate lakeinow discharges directly rom changes in the lake level.

Te lake water level is the outcome o a water balance between additions to thelake and losses, as depicted in Figure 10 and in the ollowing simple equations: 45

It ollows that:If [All River Inows + Rain] > [Evaporation + Seepage Loss], the lake levelRISESIf [All River Inows + Rain] < [Evaporation + Seepage Loss], the lake levelFALLS

Te water addition is the sum o river inows and direct rain all on the lakesur ace. Te Omo alone provides over 90 per cent o the addition. Te other riversadd about 1.6 per cent.

45 Note that, in the equations, rain refers to lake rain, this being the rainfall on the actual lake water

surface, not the land catchment. Similarly for evaporation.

Volume Change = Omo Flow + Rain + Other River Flow Evaporation Seepage Loss.

.

. Omo Flow = [Volume Change] [Rain + Other River Flow Evaporation Seepage Loss]


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Since the lake is a closed basin with no outow, the water subtraction is therelentless sur ace evaporation loss, with the entire lake volume evaporating in 11.5years. Tere will be some groundwater movement into and out o the lake, but thequantity is unknown, and by de ault, this actor is integrated within the computeddaily evaporation loss. In any case, scientic studies have determined seepage lossesto be minimal (Yuretich and Cerling, 1983). Te daily evaporation loss rom thelake sur ace was assessed by various methods, including measuring the daily drop inlake level at times when there are no known water additions - i.e., when Omo Riverinow is negligible or zero (Avery, 2012, p.129-133; Hopson et al., 1982). Te lakesur ace rain all was estimated using data rom the Meteorological Station at Lodwar,west o the lake. Tis input accounts or 8 per cent o the lake water addition.

Te simplest orm o river ow analysis is the ow duration curve, which shows therelationship between any given ow and the percentage o time the ow is exceeded(Institute o Hydrology, 1980). In Kenya, or example, the river ow that is exceeded95 per cent o the time is ofen adopted as the ow that must be lef untouchedin any river to meet downstream river needs, which include basic human needsdened in Kenyan legislation as 25 litre/capita/day (WRMA, 2012). Analysis oow duration curves or the Omo River at Omorate conrms that, as predicted in

the Master Plan, the Omos natural low ows are insufficient to sustain large-scale

Figure 10: Lake Turkana water balance model(Avery, S.T., 2012, p.208)


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commercial agriculture (Avery, S. ., 2012, p.218-219). Tese ows are even morecritical today, due to changes in the Omo catchment and abstractions to meet waterdemands along the river. Without Gibe III, then, the irrigation schemes now beingimplemented in the Lower Omo would, as expected, not be easible (ibid.).

Gibe IIIs dampening effects and the potentialdestruction of sheriesAbout 67 per cent o Lake urkanas inow will pass through Gibe III. Hence thisportion o the ow will no longer ollow natural hydrological cycles, but will instead bea controlled ow, released through turbines. Te remaining 33 per cent o the ow willbe contributed by the residual catchment, downstream o Gibe III between the dam andthe lake. Tis residual will preserve a degree o natural ow variability, but only untilthe downstream Gibe IV and Gibe V schemes are implemented. Gibe IV is planned toentail a huge reservoir, similar to Gibe III. Hence, when all three dams are in operation, virtually the entire inow to Lake urkana will be regulated and will thereby losealtogether its natural variability. Figure 11 shows the average monthly rate o ow or inows to the lake, be ore Gibe III(natural hydrograph) and afer Gibe III (regulated hydrograph), as presented by theproject consultants (Agriconsulting and Mid-Day, 2009). 46 Te average monthly rateo ow is dampened to the extent that or 10 months o the year, there is little change

in monthly discharge. Te high inow months (July-September) will have diminishedows, whereas the average low ow o less than 200 m3/s will be raised to a minimumo 500 m3/s minimum. In the be ore Gibe III scenario, the average peak monthly owis over 8-times the lowest monthly ow, whereas in the afer Gibe III scenario, theratio alls to just over twice the lowest monthly ow, a quarter o what it was be ore.Te consequent dampening impact on the lake level o the proposed average yearregulation regime introduced by Gibe III is shown in Figure 12. Based on averagemonthly ows, the typical 1,100 millimetres lake-level rise and all cycle is dampened to700 millimetres. Tis could have a potentially devastating effect on the lakes sheries.

A belated assessment o the impact o Gibe III on Lake urkana levels was producedby the dam builder (Salini, 2010). Te methodology was similar to that o my draf

46 The key measure belatedly introduced in this document to mitigate the downstream impact ofthe dam was a controlled ood, to last ten days annually in September. This could only have beencontemplated because the Gibe III project documents overlooked the likely scale of irrigationdevelopment in the Lower Omo. The proposed controlled ood has since become redundantbecause it would be regulated by, and potentially damage, the extensive irrigation and associatedinfrastructure needed for the Kuraz and other irrigation schemes.


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Figure 11: Proposed regulated ow sequence from the Gibe III dam(Based on Agriconsulting and Mid-Day International, 2009)

Changing the average annual hydrograph from natural to regulated

Net Omo inows are plotted(Adjusted for average rainfal and evaporation @7.2mm/d) Lake surface area = 7,000 sq km

Figure 12: Dampening effect of Gibe III and lake level changes

(Avery, S.T., 2012)


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AFDB report, and the timing pre-empted my nal report. 47 Tis Salini report statedthe lake area is barely inhabited (ibid., p.2), which was presumably meant toimply that impacts will be o little consequence. Te report concluded that Gibe IIIwill sensibly reduce the lake level uctuations and may benet the lacustrineenvironment (ibid.). Tese statements are diametrically opposed to the views osheries experts, discussed below, and clearly demonstrate little understanding o theecological driving orces o this particular lake.

In the tropics, ood plain sheries are reportedly the most productive (Welcome,1979 and Junk et al., 1989, both cited by Kolding & Zweiten, 2012). Studies haveshown that productivity increases with instability, that lake level changes promoteinteraction between aquatic and terrestrial systems (Kolding, 1994) and that annualuctuations in lake level are very much more signicant than absolute lake levels

(Karenge and Kolding, 1995). Lake urkanas peak production rates have beenassociated with peak rises in lake level, with declining production rates associatedwith alling lake levels (Kolding, 1992). Lake urkana is seemingly in a perpetualstate o change, with sh yields, species composition and main shing groundsrecurrently undergoing unpredictable and drastic trans ormations (Kolding, 1992,p.33). Te lake is an unstable ecological system with the biological processes highlygeared to the hydrological regimes (ibid., p.23). Tis makes it very different indeedunique when compared to other A rican Great Lakes (ibid.).

Ecologists recognise that diversity is a consequence o change and variability. Henceregulation o the Omo river ow, which dampens the natural river and lake levelcycles, as well as the speed at which the cha

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