Environmental Flow Assessments to Conserve Aquatic Ecosystems: World Bank Experience. Rafik Hirji and Stephen F. Lintner World Bank May 2010

Transcription

1 Environmental Flow Assessments to Conserve Aquatic Ecosystems: World Bank Experience Rafik Hirji and Stephen F. Lintner World Bank May 2010

2 Infrastructure for management of floods and droughts, conjunctive use of surface and groundwater, multipurpose storage, water quality management and source protection Integrated Water Resources Management Policy/Institutional framework for supply side and demand management options Management instruments Water for People Water Supply & Sanitation Water for Food - Irrigation Water for Energy- Hydropower Water for Environment -Fiseries, Natl parks, Wetlands Other uses- Industry, Mining, Livestock, Navigation, Recreation Political economy of water management Water by usage

3 Environmental Flows Are... Not minimum flows typically defined on...basis of hydrological conditions... Flows for maintaining downstream river ecosystems in a desired state Described in terms of: dry-season and wet-season low flows; the magnitude, timing and duration of flood events.

4 Evaluation of Environmental Flow Requirements Inadequate evaluation of environmental flow requirements in water development projects has led to biased allocation decisions resulting in: Sub-optimal and inequitable allocation decisions Exacerbated water use conflicts Threatened sustainability of downstream resources Undermined the productivity of the resource base Inflation of project economic rates of return

5 Flow Regime Variables Quantity Timing Duration Frequency Rate of Change

6 Flow Regime Variables Multi-dimensional characterization of flow regime is the master variable for freshwater ecosystems I In data sparse conditions, the complexity of analysis and management is compounded

7 Environmental and Social Impact Caused by: (a) direct use or management of surface and groundwater; and/or (b) land & water use that affect catchment waters 1 st order impacts relate to effects on the quantity, timing and quality of water from (a) and (b)

8 Environmental and Social Impact Hydrological and water quality alterations may in turn cause 2 nd order impacts including primary productivity 3 rd order impacts (on the food web) with consequences on downstream aquatic ecosystems, including wetlands, flood plains, estuaries and the marine environment and downstream human communities

9 Downstream Impacts saltwater intrusion dilution capacity estuarine productivity groundwater recharge ecosystem (wetland/floodplain) integrity biodiversity loss fisheries downstream water supply for other uses, including critical & important habitats (Parks) subsistence livelihoods (flood recession agriculture, livestock supply, fisheries, etc.)

10 Integration Mechanisms Integration - Integration of EFA principles in water policies and river basin plans ) Safeguard Practices - Evaluation of downstream impacts in Environmental Assessments and Environmental Management Plans Water Re-Allocation Decisions - Enhance downstream sustainability and productivity objectives EFA for negotiations in international waters

11 Methodologies for Defining EFRs Hydrologic index method (e.g. Tennant Method) uses historical flow records for making flow recommendations; often with limited attention to ecological criteria in a few instances. Hydraulic rating method (e.g., Wetted Perimeter Method) uses the relationship between simple hydraulic variables, such as depth and velocity and discharge to develop environmental flow recommendations, and models are used to predict changes over a range of flows.

12 Methodologies for Defining EFRs Habitat simulation methods (e.g., Instream Flow Incremental Methodology) link hydraulic-discharge relationship to simulation of the extent to which conditions over a range of flows meet the habitat requirements of selected river species. Holistic methodologies (e.g., Building Block Methodology or Downstream Response to Imposed Flow Transformation) are designed to address flow requirements for the entire riverine ecosystem, and may incorporate sub-routines derived from methodologies of the first three types. Experimental approach to physically simulate habitat response.

13 Prescriptive and Interactive Methodologies Prescriptive (Tennant, Wetted Perimeter, BBM) Usually address a narrow, specific objective and result in recommendation for a single flow value or flow regime Not conducive to exploring options. Suited for application where objectives are clear and the chances of conflict is small. Interactive (IFIM, DRIFT) Focuses on the relationship between changes in river flow and one or more aspects of the river...provides a range of EFRs; explains the consequences of flow manipulations. conducive to exploring options and suited for application where eventual EFR is likely to result from negotiations.

14 New Infrastructure Lesotho Highlands Water Project Supported DRIFT development DRIFT links biophysical & social issues EF Policy (operating rules) developed EF Releases % more than planned Dam design (outlet valves) modified EF Policy river health targets largely met or exceeded Substantial downstream compensation programme instituted & implemented Adaptive management

15 Restoration of Tarim Basin, China Irrigation diversions dry lower Tarim River; desert encroachment; lakes dried out Rehabilitation improved operating practices, relined canals, improved cropping Greenbelt restored; irrigation efficiency improved Lessons Sometimes win-win Engineering part of solution

16 Restoration of North Aral Sea Excessive upstream water extraction Desiccation loss of livelihoods and health Total restoration too costly Dyke & irrigation rehabilitation restore Northern Aral Sea Lessons Ignoring downstream can be costly Transboundary coordination essential Engineering part of solution

17 Lessons Learned - Institutional Policy backing is very important Environmental flows are social flows National capacity needs development EFAs need to be integrated into SEAs and EIAs Water resources agencies can be more effect then the environmental agencies Adaptive management is necessary

18 Lessons Learned - Technical All flow components are potentially impacted and need to be assessed Environmental flows are also social flows EFA need to better capture the social dimension National capacity needs development EFAs need to provide implementable and cost effective interventions EFA outcomes need to be accessible Decision Support Systems (DSS) are important

19 Lessons Learned Emerging Issues EFA and the Water Cycle EFAs have largely been applied to rivers. Lakes, wetlands, estuaries and groundwater also provide environmental services and need to be included in EFAs. Environmental Flows and Climate Change Climate change will effect runoff and river flows with impacts on water quantity and quality. EFAs at the basin and project level need to address climate change. Environmental Flows and Water Quality Changes in flow can alter the physical, chemical and biological parameters and affect in water quality. EFA methods should improve their ability to examine water quality.

20 Environmental Flows - Guidance Environmental Flows in Water Resources Policies, Plans and Projects: Findings and Recommendations Integrating Environmental Flows into Hydropower Dam Planning, Design and Operations

21 Environmental Flows - Guidance Water Resources and Environment: Technical Notes C.1 Environmental Flows: Concepts and Methods C.2 Environmental Flows: Case Studies C.3 Environmental Flows: Flood Flows

22 Climate Change and Water Resources Management Water and Climate Change: Understanding the Risk and Making Climate Smart Decisions WWF-Bank Report on Climate Change and Freshwater Ecosystems (in preparation)

23 SEA for Water Resources Management Strategic Environmental Assessment: Improving Water Resources Governance and Decision Making

24 Contact Information Rafik Hirji Stephen F Lintner slintner@worldbank.org