OPTIMIZING ENVIRONMENTAL FLOWS BELOW DAMS

The protection of riverine ecosystems downstream from dams requires reservoir operations to satisfy environmental flow (e-flow) requirements. In practice, this often involves re-regulation of downstream river flows within the constraints of water resource demands for human supplies and irrigation. In this paper, we develop a method to assess how reservoir storage may be used more effectively to meet both water supply and downstream ecosystem needs. The latter are met by providing seasonally variable baseflows, including dry season flow recession at natural rates, and high-flow pulses and bankfull flows synchronized with natural events. A series of reservoir operating rules are derived based on both reservoir storage and reservoir inflows to trigger reservoir releases. For a given water supply reliability, the method seeks to minimize the degree of hydrological alteration below a dam. We present a case study of the Tanghe Reservoir in China's Tang river basin to show that the proposed method could help reservoir managers and planners evaluate e-flow scenarios to reduce the negative impacts of dams and reservoirs on riverine ecosystems. Copyright © 2010 John Wiley & Sons, Ltd.

[1]  Brian Richter,et al.  A spatial assessment of hydrologic alteration within a river network , 1998 .

[2]  Martin J. Baptist,et al.  Assessment of the effects of cyclic floodplain rejuvenation on flood levels and biodiversity along the Rhine River , 2004 .

[3]  David P. Braun,et al.  A Method for Assessing Hydrologic Alteration within Ecosystems , 1996 .

[4]  Geoffrey E. Petts,et al.  WATER ALLOCATION TO PROTECT RIVER ECOSYSTEMS , 1996 .

[5]  Richard M. Vogel,et al.  An Optimization Approach for Balancing Human and Ecological Flow Needs , 2005 .

[6]  Effects of spates of different magnitudes on a Phragmites japonica population on a sandbar of a frequently disturbed river , 2008 .

[7]  Guido Zolezzi,et al.  Assessing hydrological alterations at multiple temporal scales: Adige River, Italy , 2009 .

[8]  Jun Zhang,et al.  Adaptive probabilities of crossover and mutation in genetic algorithms based on clustering technique , 2004, Proceedings of the 2004 Congress on Evolutionary Computation (IEEE Cat. No.04TH8753).

[9]  J. King,et al.  A scenario‐based holistic approach to environmental flow assessments for rivers , 2003 .

[10]  M. Turner,et al.  Effect of flood regime on tree growth in the floodplain and surrounding uplands of the Wisconsin River , 2009 .

[11]  Brian Richter,et al.  Application of the Indicators of Hydrologic Alteration Software in Environmental Flow Setting 1 , 2007 .

[12]  G. A. Thomas,et al.  Restoring Environmental Flows by Modifying Dam Operations , 2007 .

[13]  Xudong Fu,et al.  Effect of altered flow regime on bankfull area of the Lower Yellow River, China , 2008 .

[14]  Li Chen,et al.  Optimizing the reservoir operating rule curves by genetic algorithms , 2005 .

[15]  Richard E. Sparks,et al.  Need for Ecosystem Management of Large Rivers and Their Floodplains These phenomenally productive ecosystems produce fish and wildlife and preserve species , 1995 .

[16]  G. Petts,et al.  Dams and geomorphology: Research progress and future directions , 2005 .

[17]  N. LeRoy Poff,et al.  The ecological limits of hydrologic alteration (ELOHA): a new framework for developing regional environmental flow standards , 2007 .

[18]  B. Biggs,et al.  Application of the ‘natural flow paradigm’ in a New Zealand context , 2009 .

[19]  J. Wayland Eheart,et al.  Reservoir management to balance ecosystem and human needs: Incorporating the paradigm of the ecological flow regime , 2006 .

[20]  Lalit M. Patnaik,et al.  Adaptive probabilities of crossover and mutation in genetic algorithms , 1994, IEEE Trans. Syst. Man Cybern..

[21]  G. Petts.  Instream Flow Science For Sustainable River Management 1 , 2009 .

[22]  B. Caruso.  Regional river flow, water quality, aquatic ecological impacts and recovery from drought , 2001 .

[23]  Jenq-Tzong Shiau,et al.  A Histogram Matching Approach for assessment of flow regime alteration: application to environmental flow optimization , 2008 .

[24]  J. Brasington,et al.  Geomorphic dynamics of floodplains: ecological implications and a potential modelling strategy , 2002 .

[25]  William W.-G. Yeh,et al.  A diversified multiobjective GA for optimizing reservoir rule curves , 2007 .

[26]  R. Tharme.  A global perspective on environmental flow assessment: emerging trends in the development and application of environmental flow methodologies for rivers , 2003 .

[27]  Li Chen,et al.  REAL CODED GENETIC ALGORITHM OPTIMIZATION OF LONG TERM RESERVOIR OPERATION 1 , 2003 .

[28]  David P. Braun,et al.  How much water does a river need , 1997 .

[29]  D. Shankman,et al.  Channel Migration and Vegetation Patterns in the Southeastern Coastal Plain , 1993 .

[30]  Duncan T. Patten,et al.  Flood flows and dynamics of Sonoran riparian forests: Rivers , 1991 .

[31]  Yanwei Zhao,et al.  Optimized reservoir operation to balance human and riverine ecosystem needs: model development, and a case study for the Tanghe reservoir, Tang river basin, China , 2009 .

[32]  J. Olden,et al.  Incorporating thermal regimes into environmental flows assessments: modifying dam operations to restore freshwater ecosystem integrity , 2010 .

[33]  Donald L. Tennant.  Instream Flow Regimens for Fish, Wildlife, Recreation and Related Environmental Resources , 1976 .

[34]  A. Arthington,et al.  Basic Principles and Ecological Consequences of Altered Flow Regimes for Aquatic Biodiversity , 2002, Environmental management.

[35]  R. Sparks,et al.  THE NATURAL FLOW REGIME. A PARADIGM FOR RIVER CONSERVATION AND RESTORATION , 1997 .

[36]  B. W. Taylor,et al.  Geomorphic variation in riparian tree mortality and stream coarse woody debris recruitment from record flooding in a coastal plain stream , 1998 .

[37]  J. Olden,et al.  Flow variability and the biophysical vitality of river systems , 2008 .

[38]  C. Revenga,et al.  Fragmentation and Flow Regulation of the World's Large River Systems , 2005, Science.

[39]  Brennan T. Smith,et al.  Sustainable reservoir operation: can we generate hydropower and preserve ecosystem values? , 2008 .

[40]  Nien-Sheng Hsu,et al.  Optimization of Reservoir Management and Operation with Hedging Rules , 2003 .