Study On Ecological Water Use And Rational Allocation Of Water Resources In Weihai City

The situation of water resources,vegetation,land utilization,forest resources and the conservation of water and soil in Weihai city were studied in this thesis.According to the analysis of the situation of water resources in Weihai city,the constitution of the ecological water use were defined.Then the coefficient of water consumption and demand for forest and crop were calculated on the base of the theory of plant evapo-transpiration and water volume balance.The volume of ecological water demand for forest and crop,the watercourse,conservation of water and soil,the wetlands and the city were calculated.At the same time,the ecological water demand in 2010 and 2020 were predicted according to the statistical analysis of the present situation of ecological water use through Cu coefficient.After calculating the water demand of social economy,the optimal model of the allocation of water resources was established based on the Fuzzy Optimization Theory.The scheme of the allocation of water resources was evaluated and optimized using this model.The results showed that:(1) The rainfall was abundant in Weihai city from 1950s to 1970s while it was less from 1980s to 1990s.The precipitation tendency was decreasing from 1956 to 2000.The rainfall decreased 5.8mm, 6.2mm,6.6mm,9.2mm annually in 1960s,1970s,1980s,1990s respectively and the annual volume of reduction of the rainfall was increasing year by year.The total volume of reduction of precipitation was as 36.5%of the average annual precipitation.The change of the erath surface water resources was similar to the precipitation.The surface runoff was much from 1950s to 1970s,while it was less in 1980s and 1990s.The amount of surface runoff had the drop tendency as 5.2mm per year from 1960s to 1990s.The contradiction of the water supply and demand was previous became the decreasing of water resources and the increasing of water demand.(2) The total amount of present ecological water use was 12.26×10~8m~3 in Weihai city.The amount of consumptive ecological water use was 10.13×10~8m~3,while the amount of consumptive ecological water use from rainfall was 7.54×10~8m~3,which accounted for 61.3%of the total ecological water use. The amount of runoff consumptive ecological water use was 2.59×10~8m~3,which accounted for 21.1%of the total ecological water use.The amount of non-consumptive ecological water use was 2.13×10~8m~3, which accounted for 17.3%of the total ecological water use.7.54×10~8m~3 of the consumptive ecological water was used for vegetation and crops,which accounted for 61.3%of the total ecological water use. The volume of the ecological water use for vegetation and crops constituted the biggest portion of the total present ecological water use.The main part of the total present ecological water use was consumptive ecological water use from rainfall.(3) It was predicted that the total amount of the ecological water demand would be 17.68×10~8m~3 in Weihai city in 2010.The amount of ecological water use of the vegetation and crops would be 12.47×10~8m~3,which accounted for 70.5%of the total ecological water use.With the improvement of ecological environment,such as the protection of the vegetation,the reforestation of the city,the transformation and the restoration of the wetland and the development of water conservancy,the ecological water demand would increase further.The amount of ecological water demand would increase 5.43×108m3 and6.64×10~8m~3.in 2010 and 2020 respectively.The amount of ecological water use of the vegetation and crops would increase 4.93×108m3 and 5.95×10~8m~3 in 2010 and 2020 respectively,which would increase more quickly than others.The scale of the ecological construction was moderate from the prediction.It was suggested that the reasonable plan of the allocation of the rainfall,the water resources and the ecological water use should be made to avoid the contradiction of the water consumption between ecological and economical construction.(4) The ecological water demand included the ecological water demand and use of the rivers, wetlands(reservoir) and urban green land in Weihai city,which were incarnated as decision or restraint variables in the allocation model of water resources.It would be difficult to meet the water demand of the city after the supply of the external water,recycled water and the sea water in 2010 and 2020.In order to achieve the balance of water resources supply and demand,three measures,such as,adjusting the water use for farming and vegetation irrigation,improving the efficiency of water use through water saving irrigation,enhancing the use of the sea water and recycled water.(5) The amount of the water resources available for use was controlled by the output water volume in Weihai city.As the contradiction between water supply and water use was more obvious and the water pollution was more serious than before,the balance between the output and input of water volume could not be maintained if the emergency plan was not adopted in 2010 and 2020.Water resource shortage would be a serious problem in some area if the water quality was concerned.Therefore,The result suggested that several measures should be taken to stabilize and increase the volume of water supply.Firstly,new water source project,water facilities construction,water conduction through dams and especially the water project of Jiaodong should be put in practice.Secondly,water saving technology should be used in agriculture,industry,ecological environment and ordinary life.Thirdly, the water pollution should be controlled effectively and the use of recycled water should be increased. Last,the water resources should be allocated reasonably.