Ecological Risk Analysis And Management Research In Hydropower Development

The impact of humanactivities onecosystemsis becoming increasingly significant.In theconstruction and operation processesof large-scalehydropower projects,spatial and temporaldistribution ofriverwater has been changed; meanwhile the ecological environment of river basin is affected directly and indirectly. The influence manner and degree is different in construction period and operation period, and the environmental influence of hydropower project can be cumulative. On the other hand, the reservoir risk in flood control, power generation, water supply and navigation is changing due to different operation methods.Based on international advancedecological risk assessmentandmanagement conce ptsand methods, through researchonthe relationshipof cascadehydropower projectsand watershedecological environment, the Lancangriver hydropower system is taken as background with application of uncertainty analysistheory. The ecological risk evalu ation and decision during construction and operation period is discussed. Progresses is made in the riskofterrestrial ecosystems, fish ecological impact prediction of hy dropower projects, cumulative impact of ecological system and risk analysis and d ecision theory during hydropower operation period:(1) Risk assessmentof hydropower developmenton terrestrial ecosystemimpacts.B ased onthe concept of relativeriskand fuzzymembership theory.risk assessmentmodeli s proposed to qualitativecalculate and evaluate the terrestrial ecosystemimpacts. Terr estrial ecosystemrisk assessment index system is established for construction period and operation period of hydropower project, terrestrial ecosystemrisk assessment model is established based on relative risk theory and fuzzy membership, which ef fectively solve the multiplicity, randomness, fuzziness, incompleteness, uncertainties and othercharacteristics of watershed ecosystemevaluation, thus providesvaluablemet hods and decision making support for ecosystemandwatershed protection.(2) Prediction research of fish ecology impact from hydropower development. Fish impact prediction model is established based on improved geneticprogramming algorithm. For the deficit that geneticprogramming algorithm is difficult to conver ge tothe global optimum, usinguniform gradientto increasegenerationofindividuals an d group generation to improve the quality of initial groups, and dynamic restrictio n tree depth to improve the efficiency of algorithms. By application in Lancang ri verhydropower development and Meikong river fish impact, the prediction precision, results intuitive and interpretability of improved genetic programming is better tha n traditional genetic programming algorithms, which provides an effective way for fish impact of hydropower.(3) Cumulative effect research of ecological system for hydropower developme nt. Given theimpact ofhydropower developmenton ecosystemsare cumulative, assess ment system for environmental cumulative impact are established; for the various uncertainties of ecological system, a two stage comprehensive fuzzy evaluation mo del is established from water environment, terrestrial ecosystemsand aquaticecologic alenvironment aspect combining quantitativeand qualitative analysis. AHP theory is applied to solve the weight of each factor, and PCA theory is used to solve fuzzy assessment model, which reduced the model dimension and complexity. Take the Lancang river for instance, cumulative impact analysis for cascaded hydropower to water environment and ecological environment is analyzed, and recommendations are proposed to protect ecology, which provide a new approach to the cumulative effect from hydropower development, and provideareservefor further study ofhydrop ower development andwatershedecologyrelationships.(4) Reservoir operation risk research. According to the characteristicsof reservo ir operationinvolving multipletargets,the relationships between thereservoirmulti-objec tive are analyzed, multi-objectiveandmulti-objectivedecision making method are orga nized based on reservoirs multi-objective operation decision and analysis theory, w hich provides sufficient, comprehensiveand systematicbasis for decision making for operation plan. Forrisks associated withflood control operationof cascade reservoirs, risk assessment index system is established considering destruction probability of main objectives and constraints. Jointflood control operation riskestimation model is established, which effectively considered impact risks brought by prediction error, which has significant guiding meaning for flood control decision, and provides us eful referencevalue for cascadereservoir flood controltheery and methods.