EIA ON IRRIGATION PROJECT

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Table of Contents

Title Page

Introduction ........................................................................................................ 1

OBJECTIVE .......................................................................................................... 2

Major Impacts Of Irrigation And Drainage Projects ................................... 3

HYDROLOGY ............................................................................................................................................4

Low Flow Regime ..................................................................................................................................4

Flood Regime ........................................................................................................................................5

Operation Of Dams ...............................................................................................................................6

Fall Of Water Table ...............................................................................................................................6

Rise Of Water Table ..............................................................................................................................7

WATER AND AIR QUALITY ........................................................................................................................7

Solute Dispersion ................................................................................................................................7

Agrochemical Pollution ........................................................................................................................8

Anaerobic Effects ................................................................................................ 8

EROSION AND SEDIMENTATION ...............................................................................................................9

Local Erosion .........................................................................................................................................9

Hinterland Effect.................................................................................................................................. 10

River Morphology ................................................................................................................................ 10

Channel Structures .............................................................................................................................. 11

Sedimentation ..................................................................................................................................... 11

Biological And Ecological Change ........................................................................................................... 12

Socio-Economic Impacts ................................................................................................................. 12

Population Change............................................................................................................................... 13

Human Migration ............................................................................................................................... 13

Resettlement ....................................................................................................................................... 13

Conclusions ………..……………………………………………………………………………………………………………………14

Referances ……………………………………………………………………………………………………15

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Introduction Economic, social and environmental change is inherent to development. Whilst

development aims to bring about positive change it can lead to conflicts. In the past, the promotion of economic growth as the motor for increased well-being was the main development thrust with little sensitivity to adverse social or environmental impacts. The need to avoid adverse impacts and to ensure long term benefits led to the concept of sustainability. This has become accepted as an essential feature of development if the aim of increased well-being and greater equity in fulfilling basic needs is to be met for this and future generations. In order to predict environmental impacts of any development activity and to provide an opportunity to mitigate against negative impacts and enhance positive impacts, the environmental impact assessment (EIA) procedure was developed. An EIA may be defined as: a formal process to predict the environmental consequences of human development activities and to plan appropriate measures to eliminate or reduce adverse effects and to augment positive effects.

The aim of any EIA should be to facilitate sustainable development. Beneficial environmental effects are maximized while adverse effects are ameliorated or avoided to the greatest extent possible. EIA will help select and design projects, programs or plans with long term viability and therefore improve cost effectiveness. It is important that an EIA is not just considered as part of the approval process. Volumes of reports produced for such a purpose, which are neither read nor acted upon, will devalue the process. A key output of the EIA should be an action plan to be followed during implementation and after implementation during the monitoring phase. To enable the action plan to be effective the EIA may also recommend changes to laws and institutional structures.

Irrigated agriculture is crucial to the economy, health and welfare of a very large part of the developing world. It is too important to be marginalized as it is vital for world food security. However, irrigated agriculture often radically changes land use and is a major consumer of freshwater. Irrigation development thus has a major impact on the environment. All new irrigation development results in some form of degradation. It is necessary to determine the acceptable level and to compensate for the degradation. This degradation may extend both upstream and downstream of the irrigated area. The impacts may be both to the natural, physical environment and to the human environment. All major donors consider large irrigation developments to be environmentally sensitive. An EIA is concerned both with impacts of irrigation and drainage on the environment and with the sustainability of irrigation and drainage itself. Clearly an EIA will not resolve all problems. There will be trade-offs between economic development and environmental protection as in all development activities. However, without an objective EIA, informed decision making would be impossible

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OBJECTIVE Environmental assessment is appropriate for site specific project and wider

programmes or plans covering projects or sectoral activities over a wide geographic area. Rehabilitation or modernization programmes are more common than new green field projects and raise special issues which need to be addressed by an EIA. They provide more opportunities to correct situations where the environment is adversely affected and they are usually richer in available data. Also, operation and maintenance reforms for regions or basins will benefit greatly from an EIA. As this guide has been specifically prepared to address irrigation and drainage projects, plans and programmes, it is not sufficiently comprehensive to be used to carry out environmental impact assessments of other water resources projects. Initially EIA was used for specific, particularly large scale, projects such as dams, which have obvious long-term consequences. Now, however, greater attention is given to the wider relationship between development and the environment. The relatively insignificant actions of many individual people may cumulatively have a much greater impact on the environment than a single construction project. For example a programme to support small-holder development, through agricultural credit schemes to Water User Groups, may not warrant an EIA if each scheme is considered in isolation. However, the impact within a river basin or in the water sector in a region can be significant. A sectoral or basin-wide EIA would enable an assessment of the collective impact of the programme. Whilst this increased agricultural production it also led to groundwater mining: the reduction in the groundwater level in some areas has resulted in severe environmental and economic problems. Policies and regulations are sometimes conflicting and can contribute to degradation. It is within the scope of an EIA to highlight such conflicts and detail their consequences in relation to the irrigation and drainage proposal under study. An example of conflicting policies would be an agricultural policy to subsidize agro-chemicals to increase production and an environmental policy to limit the availability of persistent chemicals. A totally laissez-faire policy will result in unsustainable development, for example through uncontrolled pollution and distortions in wealth. This creates problems which future generations have to resolve. On the other hand, excessive government control of market forces may also have negative environmental impacts. For example, free irrigation water leads to the inefficient use of this scarce and expensive resource, inequities between head and tail users and water logging and salinity problems.

A project or programme and its environmental impacts exist within a social framework. The context in which an EIA is carried out will be unique and stereotype solutions to environmental assessments are therefore not possible. Cultural practices, institutional structures and legal arrangements, which form the basis of social structure, vary from country to country and sometimes, within a country, from one region to another. It is a fundamental requirement to understand the social structure of the area under study as it will have a direct impact on the project and the EIA.

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Major Impacts of Irrigation and Drainage Projects

When considering impacts, two perspectives must be taken into account, those of: the project on the environment, and external factors on the project (externalities).

In the detailed sections below, many of the impacts described are most extreme in the case of new irrigated areas. However, rehabilitation and changes resulting from alterations to the operating infrastructure, for example, will also have environmental impacts that may not at first be anticipated. The intensification of agriculture can lead to groundwater pollution related to the increased use of pesticides and fertilizers. Improved efficiency may significantly reduce return flows which are often utilized downstream by other irrigation schemes or wildlife habitats. Similarly, upstream developments are likely to impact on an irrigation scheme either in the form of reduced water availability (surface or groundwater) or reduced water quality. Different types of irrigation will have different impacts and it should not be assumed that modern methods will have fewer impacts: they may significantly increase energy consumption and lead to social problems due to reduced employment in agriculture. Impacts will also vary according to the stage of implementation. For example, during the construction period there may be specific health and other social risks due to an influx of migrant workers living in temporary and unsanitary accommodation. Later, once the project has been operating for several years, cumulative impacts may begin to present serious environmental constraints to project sustainability. Such issues must be predicted by the EIA and mitigation measures prepared. The most common problems of and threats to, irrigation schemes are listed in Table 5, together with potential mitigation measures. Irrigation is defined as much, if not more, by farmers and managers as by the physical infrastructure; the “hardware”. Its sustainable operation is just as dependent on the “soft” environment: education, institutional building, legal structures and external support services. These are all powerful tools to ensure sustainability in conjunction with well-designed and well managed hardware and Table 5 indicates that many of the mitigation measures are “soft”. The sections below describe the most common environmental impacts associated with irrigation schemes. Under each item, both positive and negative impacts are briefly described and the most usual mitigating measures outlined. The opportunity to identify positive impacts and to propose measures to enhance such impacts should not be neglected.

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HYDROLOGY Concerned with the consequences of impacts resulting from a change in the flow regime of rivers, or a change in the movement of the water table, through the seasons. The consumptive nature of irrigation means that some change to the local hydrological regime will occur when new schemes are constructed and, to a lesser extent, when old schemes are rehabilitated. The ecology and uses of a river will have developed as a consequence of the existing regime and may not be able to adapt easily to major changes. It is also important to recognize the interrelationship between river flows and the water table. During high flow periods, recharge tends to occur through the river bed whereas groundwater often contributes to low flows.

Figure 1 a conceptual diagram of flow through a river-supplied irrigation scheme

Low Flow Regime Changes to the low flow regime may have significant negative impacts on downstream users, whether they abstract water (irrigation schemes, drinking supplies) or use the river for transportation or hydropower. Minimum demands from both existing and potential future users need to be clearly identified and assessed in relation to current and future low flows. The quality of low flows is also important. Return flows are likely to have significant quantities of pollutants. Low flows need to be high enough to ensure sufficient dilution of pollutants discharged from irrigation schemes and other sources such as industry and urban areas. A reduction in the natural river flow together with a discharge of lower quality

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drainage water can have severe negative impacts on downstream users, including irrigation schemes. Habitats both within and alongside rivers are particularly rich, often supporting a high diversity of species. Large changes to low flows (± 20%) will alter micro-habitats of which wetlands are a special case. It is particularly important to identify any endangered species and determine the impact of any changes on their survival. Such species are often endangered because of their restrictive ecological requirements. An example is the Senegal river downstream of the Manantali Dam where the extent of wetlands has been considerably reduced, fisheries have declined and recession irrigation has all but disappeared. The ecology of estuaries is sensitive to the salinity of the water which may be determined by the low flows. Saline intrusion into the estuary will also affect drinking water supplies and fish catches. It may also create breeding places for anopheline vectors of malaria that breed in brackish water. The operation of dams offers excellent opportunities to mitigate the potential negative impacts of changes to low flows.

Flood Regime Uncontrolled floods cause tremendous damage and flood control is therefore often an added social and environmental benefit of reservoirs built to supply irrigation water. However, flood protection works, although achieving their purpose locally, increase flooding downstream, which needs to be taken into account. Radically altered flood regimes may also have negative impacts. Any disruption to flood recession agriculture needs to be studied as it is often highly productive but may have low visibility due to the migratory nature of the farmers practising it. Flood waters are important for fisheries both in rivers and particularly in estuaries. Floods trigger spawning and migration and carry nutrients to coastal waters. Controlled floods may result in a reduction of groundwater recharge via flood plains and a loss of seasonal or permanent wetlands. Finally, changes to the river morphology may result because of changes to the sediment carrying capacity of the flood waters. This may be either a positive or negative impact. As with low flows, the operation of dams offers excellent opportunities to mitigate the potential negative impacts of changes to flood flows. The designation of flood plains may also be a useful measure that allows groundwater recharge and reduces peak discharges downstream. This is one of the positive functions of many areas of wetland. It is important that new irrigation infrastructure does not adversely affect the natural drainage pattern, thus causing localized flooding.

Operation of Dams The manner in which dams are operated has a significant impact on the river downstream. There is a range of measures that can be undertaken to reduce adverse environmental impacts caused by changing the hydrological regime that need not necessarily reduce the efficacy of the dam in terms of its main functions,

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namely irrigation, flood protection and hydropower. Multi-purpose reservoirs offer enormous scope for minimizing adverse impacts. In the case of modifying low flows, identifying downstream demands to determine minimum compensatory flows, both for the natural and human environment, is the key requirement and such demands need to be allowed for at the design stage. The ability to mimic natural flooding may require modifications to traditional dam off take facilities. In particular, passing flood flows early in the season to enable timely recession agriculture may have the added advantage of passing flows carrying high sediment loads can be minimized, others eliminated by careful operation. They include malaria, schistosomiasis and river blindness; this is discussed more fully in the section Human health. Rooted aquatic weeds along the shore (or in shallow reservoirs) can be partially controlled by alternate desiccation and drowning. In some parts of the world local communities are willing to de-weed reservoirs and use the weeds as animal fodder.

Fall of water table A possible advantage of reducing the water table level prior to the rainy season is that it may increase the potential for groundwater recharge. Lowering the water table by the provision of drainage to irrigation schemes with high water tables brings benefits to agriculture. Lowering the groundwater table by only a few metres adversely affects existing users of groundwater whether it is required for drinking water for humans and animals or to sustain plant life (particularly wetlands), especially at dry times of the year. Springs are fed by groundwater and will finally dry up if the level falls. Similarly low flows in rivers will be reduced. Any changing availability of groundwater for drinking water supply needs to be assessed in terms of the economics of viable alternatives. Poor people may be disproportionately disadvantaged. They may also be forced to use sources of water that carry health risks, particularly guinea worm infection and schistosomiasis. In parts of Asia there are indications that lowering the ground level may favour the sandfly which may be vectors for diseases such as visceral leishmaniasis. Saline intrusion along the coast is a problem associated with a falling groundwater level with severe environmental and economic consequences. A continued reduction in the water table level (groundwater mining), apart from deleting an important resource, may lead to significant land subsidence with consequent damage to structures and difficulties in operating hydraulic structures for flood defence, drainage and irrigation. A number of negative consequences of a falling water table are irreversible and difficult to compensate for, eg salt water intrusion and land subsidence, and therefore groundwater abstraction needs controlling either by licensing, other legal interventions or economic disincentives. Overexploitation of groundwater, or groundwater mining, will have severe consequences, both environmental and economic, and should be given particular importance in any EIA.

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Rise of water table In the long-term, one of the most frequent problems of irrigation schemes is the rise in the local water-table (water logging). Low irrigation efficiencies (as low as 20 to 30% in some areas) are one of the main causes of rise of water table. Poor water distribution systems, poor main system management and archaic in-field irrigation practices are the main reason. The ICID recommendation to increase field application efficiency to even 50% could significantly reduce the rise in the groundwater. The groundwater level rise can be spectacularly fast in flat areas where the water table has a low hydraulic gradient. The critical water table depth is between 1.5 and 2 m depending on soil characteristics, the potential Evapo-transpiration rate and the root depth of the vegetation/crops. Groundwater rising under capillary action will evaporate, leaving salts in the soil. The problem is of particular concern in arid and semi-arid areas with major salinity problems. A high water table also makes the soil difficult to work. Good irrigation management, closely matching irrigation demands and supply, can reduce seepage and increase irrigation efficiency, thereby reducing the groundwater recharge. The provision of drainage will alleviate the problem locally but may create problems if the disposal water is of a poor quality. Apart from measures to improve water management, two options to reduce seepage are to line canals in highly permeable areas and to design the irrigation infrastructure to reduce wastage. Water logging also implies increased health risks in many parts of the world.

WATER AND AIR QUALITY In general the purer the water, the more valuable and useful it is for riverine ecology and for abstractions to meet human demands such as irrigation, drinking and industry. Conversely, the more polluted the water, the more expensive it is to treat to satisfactory levels As soil salinity levels raise above plant tolerance levels, both crops and natural vegetation are affected. This leads to disruption of natural food chains and the loss of agricultural production. The critical problem of salinity is covered in the section Soil properties and salinity effects.

Solute dispersion The changing hydrological regime associated with irrigation schemes may alter the capacity of the environment to assimilate water soluble pollution. In particular, reductions in low flows result in increased pollutant concentrations already discharged into the water course either from point sources, such as industry, irrigation drains and urban areas, or from non-point sources, such as agrochemicals leaking into groundwater and soil erosion. Reduced flood flows may remove beneficial flushing, and reservoirs may cause further concentration of pollutants. Where low flows increase, for example as a result of hydropower releases, the effect on solute dispersion is likely to be beneficial, particularly if the solutes are not highly soluble and tend to move with sediments.

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Agrochemical pollution A high nutrient level is essential for productive agriculture. However, the use of both

natural and chemical fertilizers may result in an excess of nutrients which can cause

problems in water bodies and to health. Nitrates are highly soluble and therefore

may quickly reach water bodies. Phosphates tend to be fixed to soil particles and

therefore reach water courses when soil is eroded. Phosphate saturated soils and

high phosphate level groundwater are now found in some developed countries

Notes:

1. The two parameters to which fish are most sensitive are temperature and

dissolved oxygen. Oxygen is less soluble in water at higher temperatures. Also more

non-ionized ammonia, which is toxic to fish, moves into solution from NH41+ as the

temperature rises as well as with an increase in pH. The higher the ambient

temperature, the closer fish are living to their upper tolerance limit and the less able

they are to tolerate changes to their environment. Organic pollution will reduce the

dissolved oxygen content of the water.

2. A wide range of heavy metals, industrial pollutants and agrochemicals are

toxic to fish.

High levels of nitrates in drinking water can cause health problems in small children.

However, the transport of pathogens resulting from the use of excreta as a fertilizer

or from poor sanitation causes widespread health problems from viruses, bacteria

and protozoans capable of causing a range of diseases from minor stomach upsets to

cholera and hepatitis. A high nutrient level is toxic to some aquatic life and

encourage rapid rates of algae growth which tends to decrease the oxygen level of

the water and thus lead to the suffocation of fish and other aquatic biota. Clear water

enhances the effect as it enables increased photosynthesis to take place: reservoirs

and slow-moving water are therefore most at risk. Some algae produce toxins, and if

deoxygenation is severe, eutrophic conditions occur. Reservoirs with a high level of

organic pollution, including human waste, provide an ideal habitat for the breeding

of culicine mosquitos that transmit filariasis.

Anaerobic Effects Most anaerobic conditions in water bodies are the result of an oversupply of

nutrients, as discussed above, resulting in eutrophication. In reservoirs, anaerobic

conditions may occur in the deeper areas as organic material on the bed decays in

an environment with progressively less oxygen. Reservoirs should be cleared of

organic matter, prior to impoundment to limit anaerobic decomposition once the

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dam is filled. Anaerobic conditions also occur when water is so polluted as to kill

most aquatic life. Anaerobic decomposition should be avoided as it produces gases

such as hydrogen sulphide, methane and ammonia all of which are poisonous and

some of which contribute to the greenhouse effect. The production of greenhouse

gases may also be produced by irrigated rice fields and this is being investigated by

the International Rice Research Institute. Multi-level outlets may be required for

deep reservoirs to ensure that flows are sufficiently oxygenated for downstream

aquatic life.

EROSION AND SEDIMENTATION Upstream erosion may result in the delivery of fertile sediments to delta areas.

However, this gain is a measure of the loss of fertility of upstream eroded lands. A

major negative impact of erosion and the associated transport of soil particles is the

sedimentation of reservoirs and abstraction points downstream, such as irrigation

intakes and pumping stations. Desilting intakes and irrigation canals is often the

major annual maintenance cost on irrigation schemes. The increased sediment load

is likely to change the river morphology which, together with the increased

turbidity, will effect the downstream ecology.Soil erosion rates are greatest when

vegetative cover is reduced and can be 10 to 100 times higher under agriculture

compared with other land uses. However, there are a wide range of management

and design techniques available to minimize and control erosion. For erosion to

take place, soil particles need to be first dislodged and then transported by either

wind or water. Both actions can be prevented by erosion control techniques which

disperse erosive energy and avoid concentrating it. For example, providing good

vegetative cover will disperse the energy of rain drops and contour drainage will

slow down surface runoff.

Local erosion The method of irrigation profoundly affects the vulnerability of the landto erosion.

Because irrigated land is wetter, it is less able to absorb rainfall and runoff will

therefore be higher. Field size, stream size (drop size), slope and field layout are all

difficult to change and all significantly affect erosion rates. Careful design can avoid

the occurrence of erosion problems. Agricultural practices affect soil structure and

therefore the soil’s erosivity, or the ease with which particles are dislodged. In

general landforming for irrigation, such as land-levelling and the construction of

field bunds, tends to reduce erosion. Archaic in-field water management practices

involving poor cut and fill operations through watercourse embankments can result

in serious local erosion at the head end of the irrigated field and in sedimentation at

the mid or tail-end locations of the field. The micro-topography of a field will thus be

disturbed. Unavoidably, this effect creates disproportionate water distribution over

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the irrigated field. In addition it might create disputes between water users.

Improved water management practices related to surface irrigation methods (for

example by using gates, siphons, checks) can reduce such hazards. Irrigation

infrastructure needs to be designed to ensure that localized erosion, eg gully

formation, does not occur. Construction activities generally expose soil to erosion.

Following the completion of construction work, vegetation should be established

around structures so that bare soil is not exposed to erosive forces.

Hinterland effect The development of irrigation schemes in developing countries is often associated

with an increase in intensity of human activity in areas surrounding the scheme.

This may be due to people moving into the area as a result of the increased

economic activity or may be carried out by farmers and their families who are

directly engaged in irrigation activities. In either case typical activities are: more

intensive rain fed agriculture; an increase in the number of livestock; and, greater

use of forests, particularly for fuel wood. All these activities are liable to increase

erosion in the area by decreasing vegetative cover which will have a detrimental

effect on the local fertility and ecology as well as contribute to sediment related

problems. Clearing higher non-irrigated parts of the catchment can result in a

rising downstream water table. In areas where the groundwater is saline the

higher recharge may cause higher salinity levels in the rivers and cause pressure

levels in the lower irrigated areas to rise thus impeding leaching. This can be

prevented by planting deeper rooting crops and trees in the higher lands. This

phenomenon has been observed in Southeastern Australia.

Mitigating actions can be put in place relatively easily with forethought as to

problems that might arise. For example, allowance should be made for livestock,

fuel wood or vegetable gardens within the layout of an irrigation scheme.

Alternatively, protection of vulnerable areas may be necessary.

River morphology The capacity and shape of a river results from its flow, the river bed and bank

material, and the sediment carried by the flow. A fast flowing river has more

energy and is able to carry higher sediment loads (both more and larger particles)

than a slow moving river. Hence, sediments settle out in reservoirs and in deltas

where the flow velocity decreases. A river is said to be in regime when the amount

of sediment carried by the flow is constant so that the flow is not erosive nor is

sediment being deposited. The regime condition changes through the year with

changing flows.

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Reductions in low flows and flood flows may significantly alter the river

morphology, reducing the capacity to transport sediment and thereby causing a

build up of sediments in slower moving reaches and possibly a shrinking of the

main channel. Increasing flows will have the reverse effect. Where the sediment

balance changes over a short distance, perhaps due to a reservoir or the flushing of

a sediment control structure, major changes to the local river morphology are

likely to occur. The release of clear water from reservoirs may result in scour and a

general lowering of the bed level immediately downstream of the dam, the reverse

of the effect that might be expected with a general reduction in flows. Changes to

the river morphology may effect downstream uses, in particular navigation and

abstraction for drinking, industry and irrigation. The river ecology may also be

adversely affected.

Channel structures The susceptibility of channel structures to damage is strongly related to changes in

channel morphology and changes in sediment regime. Increased suspended

sediment will cause problems at intake structures in the form of siltation as well as

pump and filtration operation. Abstraction structures may become clogged with

sediment or left some distance from the water. Degradation of the river bed is

likely to threaten the structural integrity of hydraulic structures (intakes,

headworks, flood protection etc) and bridges. The construction of new structures

impacts on nearby structures by changing local flow conditions.

Sedimentation Irrigation schemes can fail if the sediment load of the water supply is higher than

the capacity of the irrigation canals to transport sediment. Sediment

excluders/extractors at the headworks can mitigate this effect to some extent.

Sedimentation from within the scheme itself can also be a problem, for example,

wind-blown soil filling canals. Canal desilting is an extremely costly element of

irrigation maintenance and design measures should minimize sediment entry.

Reservoir siltation shortens the active life of the reservoir and must be given

careful consideration at the design stage. The increases in erosion due to the

economic activity prompted by the reservoir and its access roads needs to be taken

into account. Upstream erosion prevention, particularly within the project

catchment is an important consideration of an EIA. However, this may not be

sufficient to significantly reduce reservoir sedimentation, especially in view of the

time delay between soil conservation activities and a reduction in river sediment

loads.

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Biological And Ecological Change This section focuses on the ecological changes brought about by the project. The

most obvious ones are a consequence of the change of land use and water use in

the project area but effects on the land around the project and on aquatic

ecosystems that share the catchment are likely. Biological diversity, areas of

special scientific interest, animal migration and natural industry are important

study areas. The overall habitat as well as individual groups (mammals, birds, fish,

reptiles, insects etc) and species need to be considered. Rare and endangered

species are often highly adapted to habitats with very narrow ranges of

environmental gradients. Such habitats may not be of obvious economic value to

man, eg arid areas, and therefore current knowledge of the biota may be poor and

a special study may be required. Local knowledge is particularly important as the

range of species may be very local. Thienemann’s rules are useful in thinking about

the ecology of the effected areas:

The greater the diversity of conditions in a locality, the larger the number of species in a biological community. The more conditions in a locality deviate from the normal, and thus from

the optimum for most species, the smaller the number of species and the greater the biomass of each. The longer a locality has been in a stable condition, the richer its biological

community.

Socio-Economic Impacts The major purpose of irrigated agriculture is to increase agricultural production and consequently improve the economic and social wellbeing of the area of the project. Although irrigation schemes usually achieve this objective, they could often have been more successful in developing countries if more attention had been paid to the social and economic structure of the project area. An EIA should thus equally concentrate on ways in which positive impacts can be enhanced as on negative impacts mitigated. Changing land-use patterns are a common cause of problems. Small plots, communal land-use rights, and conflicting traditional and legal land rights all create difficulties when land is converted to irrigated agriculture. Land tenure/ownership patterns are almost certain to be disrupted by major rehabilitation work as well as a new irrigation project. Access improvements and changes to the infrastructure are likely to require some field layout changes and a loss of some cultivated land. The “losers” will need tailored compensation best designed with local participation. Similar problems arise as a result of changes to rights to water. E

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Population Change Irrigation projects tend to encourage population densities to increase either because they are part of a resettlement project or because the increased prosperity of the area attracts incomers. Major changes should be anticipated and provided for at the project planning stage through, for example, sufficient infrastructure provision. Impacts resulting from changes to the demographic/ethnic composition should also be considered. Training is an important component if new skills are expected.

Human Migration Human migration (outside of the nomadic way of life) and displacement are commensurate with a breakdown in community infrastructure which results in a degree of social unrest and may contribute to malnutrition and an increased incidence of disease. Large, new irrigation schemes attract temporary populations both during construction and during peak periods of agricultural labour demands and provision for their accommodation needs to be anticipated. The problems of displacement during project construction or rehabilitation can usually be solved by providing short term support.

Resettlement Often the most significant social issue arising from irrigation development is resettlement of people displaced by the flooding of land and homes or the construction of canals or other works. This can be particularly disruptive to communities and, in the past, insensitive project development has caused unnecessary problems by a lack of consultation at the planning stage and inadequate compensation of the affected population. Technical ministries should seek expert assistance at an early stage. Community re-establishment often includes, for example, pilot farms, extension services and credit schemes.

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Conclusions The EIA process makes sure that environmental issues are raised when a

project or plan is first discussed and that all concerns are addressed as a project gains momentum through to implementation. Recommendations made by the EIA may necessitate the redesign of some project components, require further studies, and suggest changes which alter the economic viability of the project or cause a delay in project implementation. To be of most benefit it is essential that an environmental assessment is carried out to determine significant impacts early in the project cycle so that recommendations can be built into the design and cost-benefit analysis without causing major delays or increased design costs. To be effective once implementation has commenced, the EIA should lead to a mechanism whereby adequate monitoring is undertaken to realize environmental management. An important output from the EIA process should be the delineation of enabling mechanisms for such effective management.

A project or programme and its environmental impacts exist within a social framework. The context in which an EIA is carried out will be unique and stereotype solutions to environmental assessments are therefore not possible. Cultural practices, institutional structures and legal arrangements, which form the basis of social structure, vary from country to country and sometimes, within a country, from one region to another. It is a fundamental requirement to understand the social structure of the area under study as it will have a direct impact on the project and the EIA.

The link between different ministries and departments within ministries

are often complex and the hierarchy for decision making unclear. There is a tendency for each ministry to guard “its project” and not consult or seek information from other government bodies unless forced to. This is directly contrary to the needs of an EIA. Even if formal structures exist there may be a lack of coordination between different organizations. Informal links may have been established in practice in order to overcome awkward bureaucratic structures. These issues must be understood and not oversimplified. Laws designating what projects require EIA should, ideally, limit the statutory requirements to prevent EIA merely becoming a hurdle in the approval process. This will prevent large volumes of work being carried out for little purpose. Most legislation lists projects for which EIA is a discretionary requirement. The discretionary authority is usually the same body that approves an EIA. This arrangement allows limited resources to be allocated most effectively. However, it is essential that the discretionary authority is publicly accountable.

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REFERANCES The FAO series of Irrigation and Drainage Papers

Environmental Impact Assessment - Theory and Practice

The Environmental Assessment Sourcebook”, World Bank

Technical Paper No. 140 (1991)

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JEC

T