生态环境需水研究.pptVIP

? Mark Godfrey Brian Richter, Director Global Freshwater Program ? Insert Image Credit Environmental Flows for People and Nature From “Rivers for Life: Managing Water for People and Nature” by Sandra Postel and Brian Richter, Island Press 径流量 m3?s-1 年内过程 低 流 量 高 流 量 洪 水 This is the same volume! Definition of Environmental Flows “Environmental flows” describe the quantity, timing, and quality of water flows required to sustain freshwater and estuarine ecosystems and the human livelihoods and well-being that depend on these ecosystems. Source: The Brisbane Declaration, International RiverSymposium, September 2007 Maintaining Natural Flow Patterns From “Rivers for Life: Managing Water for People and Nature” by Sandra Postel and Brian Richter, Island Press adapted from Tharme and King 1998 The Big Question How much flow alteration e.g., from dam operations and water withdrawals is too much? 0 50 100 150 0 5 10 15 wet-season low flow range dry-season low flow range Water depth m Cross-channel distance m 1:2 y flood 1:5 y flood Establishment of links between flow events, channel hydraulics biophysical components Aquatic Wetbank Drybank Sedge Moss Lower shrub Upper shrub/tree Inter-annual flood events JAN FEB MAR APR MAY JUN JUL AUG SEP OCT NOV DEC Environmental Flow Building Blocks Savannah River, below Thurmond Dam River-Floodplain Low Flows High Flow Pulses Floods 3,000 cfs; 3 successive years every 10-20 years Floodplain tree recruitment 5,000 cfs Adequate floodplain drainage Create shallow water habitat for small-bodied fish 8,000 cfs Larval drift for pelagic spawners 50,000-70,000 cfs; 2 weeks, avg every 2 yrs Maintain channel habitats Create floodplain topographic relief Provide fish access to the floodplain control invasive species Maintain wetlands and fill oxbows and sloughs Enhance nutrient cycling improve water clarity Disperse tree seeds 13,000 cfs; 3 successive years, every 10-20 years Floo