Study On The Water Ecology Comprehensive Evaluation Of Representative Reservoirs In Shandong Province

In recent years, water pollution disasters are prone and water security has been raised to the height of strategic development, so people pay more and more attition to water ecosystem health and drinking-water safety. As surface water supply sources, reservoirs play important roles in urban and residents’life, industrial production, ecology and agricultural irrigation. Reservoirs’ ecological status is directly related to water security and social stability. Therefor, to make reasonable evaluation and protect the safety of the reservoir water ecosystem have become the most important part in the current and even subsequent water resources work.Based on ecosystem health and water-ecological environment assessment, the comprehensive evaluation indexes system of reservoir ecosystem were constructed by the analytic hierarchy process, including four secondary indicators named water quantity, water quality, aquatic organisms and eutrophication and the third indicators that mainly refer to physical, chemical and biological indexes. Water level was choosen as evaluation index to rank quantity according to the reservoir characteristic level. Therefor, the single factor evaluation was used as evaluation method of water quantity. Combined with monitoring indexes and sequence length, this research had choosen DO, NH3-N, COD, CODMn, BOD and TP as indicators and used fuzzy comprehensive evaluation to assess water quality. In addition, the evaluation standard was also improved on the basis of the Surface Water Environment Quality Standard (GB3838-2002). As for eutrophication assessment, chlorophyll a, TP, TN and CODMn were choosen as indicators. By comparing evaluation results of the trophic state index and comprehensive trophic state index, the trophic state index whose result was worse was adopted following the idea of the most rigorous water resources management. At last, the fuzzy mathematical method was used to establish the comprehensive evaluation model of reservoir water ecology to calculate level characteristic value to determine the reservoir ecology.The fuzzy comprehensive evaluation model of the reservoir ecology was used to assess six representative reservoirs in Shandong Province on the basis of a certain length monitoring data. The high goodness of fit between evaluation results and realities of situation had validated the rationality of the evaluation model. Given the importance of quatity to reservoir ecology, component analysis was carried out on quality factors with reference to the hydrological sequence analysis method. After that, the study explored the reasons for the change of reservoir water quality and ecological environment, according to the sequence characteristics, such as the jump, trend and periodic components. Then combined with evaluation results and actual operation, predictions about the development trend of reservoir water ecology and suggestions about protecting and improving reservoir ecological status were made. The results show that the water ecology of the six representative reservoirs are above the middle level and relatively stable. But the phenomenon that exceeding standard on water quality lead to substandard ecology appears in some reservoirs in some years. Finally, the study makes a conclusion that the reservoir ecosystem is mainly influenced by surrounding economic and social development and utilization of water resources. Based on this, suggestions on the protection and improvement of reservoir ecosystem including engineering, non-engineering and rules are put forward, which can provide technical support for rational evaluation of reservoir ecosystem and water conservation work.