Study Of Ecological And Environmental Water Requirements In Shiyang River Basin

In the history of water utilization and development in Shiyanghe Basin, our attention has always been paid on the benefit we could get from rivers while environmental and ecological function of the river system used to be neglected. Thus the activities of water utilization and development were accompanied by more and more serious environmental and ecological problems, for example, drying up of the river channel, riverbed deposition, and degradation of estuarine delta, are arising from excessive utilization of water resources in the Shiyanghe River Basin. Therefore, how to ensure water requirement of the watershed ecosystem is a crucial factor for the ecosystem conservation.The research has studied the ecological and environmental water requirements in the Shiyanghe River Basin. Two aspects of research are included in this paper. One is to study the ecological and environmental water requirements of the basin theoretically from the point of view of the ecological conservation; the purpose is to analyze its spatial-temporal variation and ecological water shortage in the basin. The other is to study water required by ecosystem in water resources allocation of the basin from the point of view of ecological conservation and economic development; the aim is to realize the combination of its theory and application and to offer scientific foundation for rational water resources allocation of the basin. The following contents in detail are included in this research:1 In order to reduce the environmental and ecological problems induced by water sources development and utilization, this paper has proposed concept of environmental and ecological water consumption. In general, we defined that the environmental and ecological water consumption means the minimum water that must be saved in or consumed by the natural water bodies to conserve their environmental and ecological functions.2 Based on the definition, the methods on calculating the amount of environmental and ecological water consumption are determined. Water consumption can be divided into five parts, i. e. the basic water consumption of rivers, water consumption for transportation of sediments, water consumption for evaporation of the lakes, water consumption for replenishment of groundwater, water consumption for different ecosystems. The methods for calculating the different parts of water consumption were shown in expressions.3 The results of the calculation have shown that the environmental and ecological water consumption in the Basin is about 11.0472×10~8m~3, including 2.4586×10~8m~3 for basic consumption, 5.30×10~8m~3 for transportation of sediments and 1.53×10~8m~3 for net evaporation loss of lakes and Reservoirs and, and 1.7586×10~8m~3 for water required of replenishment of groundwater. Thus the integrated water required for ecology and environment took up about 36.49%～48.60% of the total water resources. However, there are still some aspects of environmental and ecological consumption that are not under our consideration. It should be realized that the required amount of environmental and ecological water consumption must be more than that we have calculated.4 The total environmental and ecological water requirement in Shiyanghe basin is 8.502×10~8m~3, including the total suitable ecological water requirement of the forests, environmental and ecological water requirement of the grasses and environmental and ecological water requirement of the hungriness, which are 1.5714×10~8m~3,6.8089×10~8m~3,0.1217×10~8m~3According to this result, the current utilization rate of the Basin is too high. It is on the urgency to control and adjust water development and utilization to eliminate those problems existed and to avoid the potential ecological or environmental crises that are still not clear.