Environmental Impact Retrospective Evaluation Of Hydropower Development Based On "3S" Technologies

Retrospective evaluation is an important part of environmental impact evaluation onhydroelectric project,and is a useful complement to project environmental managementmeasures,which can help to measure the environmental impact of projectcomprehensively and accurately,and can provide further strengthening environmentalmanagement project with scientific basis and offer reference for environmental design andenvironmental impact retrospective evaluation of other project simultaneously．Throughretrospective evaluation,the environmental benefits and adverse effects of hydropowerdevelopment project can be assessed objectively and fairly．In this paper,the environmental impact of Ertan Hydropower Station on the Yalong isevaluated retrospectively and dynamically based on"3S"technology．Main researchworks are the following:(1)In the study period from 2006 to 2008,the author has surveyed the ErtanHydropower Station reservoir in typical periods,and obtained the valuable first-hand dataand information．(2)Ten-year regularity of rainfall,relative humidity,and air temperature,including 1988-1997 and 1999-2008 respectively,was analyzed by the linear tendencyestimate model,sudden change examination of which was done by Mann-Kendall model,and further,the impact of Ertan hydropower project on local climate was analyzed．(3)Under the guidance of landscape ecology theories and methods,four-time landuse landscape pattern and the dynamic changes were analyzed quantitatively by GIS andFRAGSTAT software using four-time Landsat TM/ETM+ images,which are 1988,1999,2003 and 2006 respectively．(4)The dynamic changes of soil erosion before and after the hydropower station runwere analyzed by RUSLE(Revised Universal Soil Loss Equation)model based on RSand GIS technologies．(5)On the basis of individual evaluation on hydropower development environmentalimpact,soil erosion intensity,vegetation index,soil brightness index,humidity index and heat index were selected as evaluation indexes,the weight of which was determinedby AHP(Analytic Hierarchy Process),and the environmental quality changes wereevaluated based on graphic overlay method by the support of GIS．(6)Based on comprehensive analysis and evaluation,according to the impactson environment from Ertan hydropower development project,some targeted solutionswere proposed．Main important results are the following:(1)The technical methodology system of hydropower development environmentimpact retrospective evaluation was founded based on"3S"technologies．Thegeographical coordinate information can be easily obtained by GPS,as the auxiliary toolof field test．Based on earth surface information,which can be got objectively from RSimages,land use information,vegetation cover,soil brightness index,humidity indexand hot index,et al,were extracted,and used to evaluate individually orcomprehensively the hydropower development environment impact．Because of theobjectivity"3S"technologies in information acquisition,processing and analysis,evaluation results were more practical．(2)Ertan Hydropower Station,which has the largest installed capacity of thosecompleted in the late twentieth century in China,has operated safely more than ten yearsby now．The project,which locates in the dry-hot valley areas,it's ecologicalenvironment was fragile,which was representative．Through the single andcomprehensive evaluation,it was believed that,environmental quality of ErtanHydropower Station reservoir and its surrounding was improving as a whole,but wasdeteriorated locally．This study has evaluated the Ertan hydropower developmentenvironmental impact more fairly,objectively,and comprehensively at first,providedcurrent hydropower development with decision-making support and other hydropowerproject environmental impact with an analogy example．(3)The graphic overlay method in GIS environment has been expanded andenriched the environmental impact evaluation methods．As the huge advantages of GIStechnology in spatial data acquisition,storage,management,processing and analysis,its organic integration with graphic overlay method makes the evaluation more conciseand faster,and have realized quantification and specialization of evaluation results．...