VNMC Mekong Dam Study project overview part 1

Study of the Impacts of Mainstream Hydropower on the Mekong Delta

MDS Impact Assessment Framework, Approach, and Results Overview

Greater Mekong Forum on Water, Food and Energy

Phnom Penh, Cambodia

October 2015


Outline

� Project overview

� Study area

� Impact assessment

– Objectives

– Approach

� Baseline data

Historical data

Research studies

� Data issues

� Impact assessment results overview


Project objectives and study area

MDS Evaluation Area MDS Impact Assessment Area IAA Sub-divisions

� To assess the overall impacts of the proposed LMB mainstream

hydropower cascade on the natural, social, and economic systems of

Cambodian and Vietnamese floodplains.


� Cambodian Floodplains Kratie to Phnom Penh (includes

the Great Lake - Tonle Sap System

(approx 5,690,683 hectares)

� Cambodian Delta Phnom Penh to Vietnamese

Border (approx 930,811 hectares)

� Vietnamese Delta Vietnamese border to East Sea

(approx 3,926,565 hectares)

The IAA covers approx 10.5 M hectares

� Includes Ecozones 4, 5, and 6


� 13 provinces in Viet Nam

– 128 Districts, 1,589 Communes

� 14 provinces in Cambodia

– 121 Districts, 1,057 Communes

The IAA includes 27 provinces


Impact assessment was focused on areas that are

hydrologically connected to the Mekong River

mainstream

Flooded area duration map (7 days_10 cm)� Hydrological connection =

inundation potential

� Flooding defined as:

– 10 cm inundation over 7 days

� Using this definition the year 2000

flood would have inundated

approx. 40,955 km2 within the IAA

– About 40% is in the Vietnamese delta

(15,970 Km2)


Drivers and receptors

� Key drivers of change: Flow regime, sediment

loading, water quality,

longitudinal connectivity

(barrier effects)

� Potential impacts on:

– Natural systems Biological habitats, biodiversity

– Social systems Livelihood

– Economic sectors Fisheries, Agriculture, Navigation


Linkages between drivers and resources are complex, dynamic,

and multifaceted and include multiple feedback loops.


Linkages between direct and indirect impacts are mediated by

multiple bio-physical and social factors.


Net impacts will be influenced by the macro-level feedback loops

between institutional, natural, social, and economic systems.


� Evaluate and quantify (where permitted by data availability and

quality) direct and indirect impacts of:

– Changes in flow regime, sediment loading, and water quality on

– Extent of wetlands, biodiversity, fisheries, agriculture, navigation,

livelihood, and economic impacts

– Impacts to aquatic species due to barrier effects were also evaluated

� Alternative operational strategies were considered (dry year-dry

season and dry year-wet season drawdowns)

� Positive and negative and short- and long-term impacts

Impact assessment approach


� Impacts were cumulatively assessed across geographic areas:

– Cambodian floodplains

– The Great Lake – Tonle Sap System

– Vietnamese Delta

– Provinces and districts (livelihood, agriculture, and economic impacts

only)

� Where relevant, impacts were cumulatively assessed across

sectors

Impact assessment approach

Sectors FisheriesBiodiversi

tyAgriculture Navigation Livelihood Economics

Fisheries X X X X

Biodiversity X X X

Agriculture X X X X

Navigation X X X

Livelihood X X X X

Economics X X X X X


� Extremely large study area with very complex ecosystem characteristics

– influenced the resolution of the analyses

� Lack of existing scientific tools/knowledgebase

– No suitable off-the-shelf tool were available to correlate changes in sediment and nutrient loading to potential changes in biodiversity and fisheries yields

� Vietnamese Delta is highly altered

– influenced outcome of the agriculture and aquaculture impact assessments

� Data issues

– Influenced level of quantification of impacts

Impact assessment challenges


� Quantity

– Available collected at disparate locations, at different times, using varying

methodologies, for different purposes

� Quality

– Lack of raw data, little or no information on analytical and QA/QC procedures

� Accessibility

– Many different institutions collect data for different purposes

– hard copy v/s electronic

� Period of record

– Varying data collection periods and frequency

– Some data is simply too old

� Critical gaps

– Focused research studies to fill the gaps

Data issues


� Biodiversity

– Field Surveys within selected land cover types (5 sites, 3 seasons)

– Characterization of water management practices within selected

national parks and wetland reserves

– Wetlands map update

� Fishery

– Habitat-based fish sampling surveys (39 sites, 6 sampling events)

– Fish yield sampling surveys

– Fisher surveys.

– Aquaculture production assessment

� Livelihood

– Household surveys

– 2,520 households in Vietnam

– 720 households in Cambodia

Research studies


� Sediment

– Quantification of sediment loads under dry and wet weather conditions

– Data collected in Laos PDR, Cambodia and Vietnam

– Compare to the 2011 – 2013 DSMP data

� Water Quality

– Nutrient transport associated with sediment transport

– Nutrient dynamics related to the transport and deposition/re-

suspension of sediments

� Navigation

– Data on key navigation parameters is being collected through

questionnaire interviews at 14 sites in Vietnam and 5 sites in Cambodia

Research studies


� Hydro-meteorological conditions for the 1985–2013 period of

record

– includes extreme years (very wet [2000 and 2011] and very dry [ 1998])

and average years [represented by 2007])

– hydrologically representative of the conditions likely to occur in the LMB

in future

� Salinity in the Delta (2007-2013)

� Sediment transport, nutrient transport (2009-2013)

� Environmental, social and economic conditions – 2011 to 2012

(supplemented by data collected during 2014)

Baseline conditions


� Scenario 1 – Mainstream hydropower cascade

� Scenario 2 – Mainstream hydropower cascade plus tributary

dams

� Scenario 3 – Mainstream hydropower cascade plus water

diversions

Hydropower development scenarios

VNMC Mekong Dam Study project overview part 1

Science

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