The Water Ecosystem Health Assessment Of Yinghu And Protection Countermeasures

Yinghu is located260kilometers upstream of the Dan Jiang Kou reservoir whichbelongs to South-to-North Water Diversion Project. Yinghu supplies over60%ofreservoir yield of Dan Jiang Kou reservoir and it is the drinking water source for AnKang city and surrounding towns. The water environment and water ecosystem ofYinghu play an important role in water quality security of the Middle Route Project ofS-N water diversion and People’s production and living in An kang.The water environmental assessment include water quality evaluation andeutrophication assessment. Based on the sufficient investigation, the water quality ofYinghu during2010to2013is evaluated by using single-factor appraisal, syntheticalpollution index method and Nemerow index method，respectively. The water qualitychange trends were determined by Daniel trend test method. The single-factorevaluation indicates that the water quality situation from2010to2011did not meet thestandard of surface water environmental function areas (class Ⅱ of Environmentalquality standard of surface water) and the water quality situation from2012to2013wasup to standard. Total phosphorus and chemical oxygen demand exceeded the standard,the over standard rate was50%and8.3%respectively. The synthetical pollution indexmethod evaluation result shows that the index from2010to2013was between0.4992and0.6915. The water quality situation was slightly polluted. Nemerow index methodevaluation result shows that the index from2010to2013was between0.8452and1.1957. The water quality situation in January2010and2011was slightly polluted, thewater in other times was of high quality. The synthetical pollution index and Nemerowindex within a year were in downward trend, suggesting that the water quality in rainseason is better than in dry season.The changing trends of permanganate index, five-day’s oxygen demand and total phosphorus were significant. Permanganate indexand five-day’s oxygen demand showed an upward trend. Total phosphorus showed adownward trend.Other water quality shows no significant change.The syntheticalpollution index decreased slightly, while the Nemerow index decreased significantly.The eutrophication degree and eutrophication change trend of Yinghu wasevaluated comprehensively by comprehensive trophic status index. The eutrophicationdegree of Yinghu revealed a rising trend during the period of1986to2005and was atlow eutrophication level before1995.After2005, the changes of the eutrophication stateindex of Yinghu were small and the degree of eutrophication of Yinghu was at themiddle level.An appraisal system for estimating the water ecosystem health status of Yinghuwas established by using entropy weight comprehensive health index method using15indicators of physical-chemical indicators, ecological indicator and socio-economicindicator. The water ecosystem health of the Yinghu during the period of1986to2012was estimated. The results showed that during the period of1986to2005, thecomprehensive health index of the water ecological system of Yinghu was in a declinedtrend and the aquatic health level dropped from health to morbidity. During the periodof2005to2012,the comprehensive health index of the water ecological system ofYinghu revealed a rising trend and the aquatic health level are sub-health except in2010.The strategies for protecting the ecological system are proposed according to thesituation of ecological system of Yinghu by reinforcing pollution control of basin,promoting optimal regulation of social economy, beginning ecological conservation andreinforcing ecology and environment management,etc.