The Study Of Multi-scale Health Evaluation Of The Cascade Hydropower Development On The Jialing River In Sichuan

The Jialing River, which is the largest tributary of the upper reaches of the YangtzeRiver Valley is an important part of the ecological security barrier of southwest China,meanwhile, it is one of the important factors influencing the water environmentalsecurity of the Three Gorges Reservoir Area. The cascade hydropower development ofthe Jialing River promotes the local economic development, however, the constructionand operation of the project bring greater influence to the local ecological environment,biodiversity and water quality, accompanying by excessive pollution discharge ofhuman and soil erosion as well as other environmental pressures, the environmentalsecurity issues of the Jialing River cannot be ignored. The environmental influence ofthe river cascade hydropower development is investigated and summarized in this paper,and the health evaluation management method is adopted to carry out multi-scale healthevaluation of the cascade development on the Jialing River in Sichuan following themodel of “pressure�'state�'response”. Sustainable development of the cascadedevelopment on the Jialing River is also systematically studied in this paper, whichprovides a theoretical support to enhance the river’s level of integrated management.The main findings are as follows:Define multiple space-time scales of the river system, analyze the basiccharacteristics of the health evaluation of each scale, according to the space-timerelationship after the cascade development on the Jialing River to select the planktondiversity index and fish-index of biotic integrity as well as multi-index comprehensiveevaluation method as the multi-scale health evaluation method of the Jialing River.Construct the fish-index of biotic integrity system and multi-index evaluation modelsuitable for the Jialing River’s health evaluation.Through the field collection and analysis of plankton in the reaches of the cascadedevelopment on the Jialing River, phytoplankton is collected with a total number of8divisions,42familiae,95genera and171species (including varieties),The numbers ofspecies in Bacillariophyta, Chlorophyta and Cyanophyta were richer than others. andthe average cell density of phytoplankton is12.9×10~4ind/L. The collectedzooplankton includes a total of4classes,9orders,21families,30genera and62species,which respectively belong to the protozoa, pseudocoelomata and arthropoda, theaverage density of zooplankton is2854.4ind/L, and the average biomass is2.331mg/L, there are21kinds of dominant groups. The shannon diversity index, Margalef richnessindex, Pielou evenness and other indexes are adopted, with the combination of indicatorspecies to assess the water quality. The evaluation results show that the water quality inthis reach is moderately polluted, after channelizing; the self-purification capacity of theJialing River declines and the water body in Sichuan is polluted to a certain extent. Themethod of using plankton to evaluate the water body has a strong diagnostic ability,sensitivity and accuracy.The investigation shows that there are129kinds of fish distributed in the middlereaches of the Jialing River (including the whitebait collected this time).263fishspecimens are collected in this investigation, which respectively belonging to26species,7familiae and4ordines;21kinds of fish are investigated by visiting. Most of which isthe economic fish; The endemic and rare fish in the upper reaches of Yangtze River arenot dominant anymore; Due to the reduction and disappearance of environments such asrush water and running water, typical accommodators and specializations fit for rushand running water such as Homalopteridae and Sisoridae as well as others are almostdisappeared in the reservoir area. The integrity evaluation results of fish in the JialingRiver show that, the rating of biological integrity evaluation in the reaches of thecascade development on the Jialing River is worse than medium, and the ecologicalenvironment is seriously disturbed by human activities; Fish integrity evaluation systemconstructed in this study can better express the cybotaxis condition of fish and thecontinuity and integrity characteristics of ecology in the reaches of cascadedevelopment on the Jialing River.Select the method based on fuzzy comprehensive evaluation model to carry out acomprehensive evaluation of the health state of the Jialing River. The evaluation showsthat the overall health state of the cascade development on the Jialing River (Sichuan) issub-health. The health state in the upper reaches and the high water period is in a bettersituation of health; The health state in the Cascade Reservoir area, the rainless period,the middle and lower reaches is in a state of sub-health. The analysis shows the mainindicators influencing the health state of the Jialing River are soil erosion rate and fishFIBI. The multi-index evaluation results of the Jialing River are consonant with thepractical situation, and better reflect the health state of the cascade development on theJialing River (Sichuan); The model and method of multi-index health evaluationconstructed in this paper are suitable for the health evaluation of rivers in process ofcascade development. In summary, main environmental pressures of the Jialing River include themainstream’s geological and environmental problems, cascade navigation engineeringand excessive pollution discharge of human, it is now in a state of sub-health, thusappropriately targeted management strategies should be taken. The results of this studyplay a role of demonstration and guidance in the health evaluation of rivers concerned.