The Analysis Of Ecological Water Requirement And Water Balance In Tuhai River

Changes in the quantity and quality of water resources have an impact on the ecological structure and ecological function in the river basin. In order to maintain the structure and function of the ecosystem, the consumption of water resources amount is the ecological water demand, it includes inner and outer river ecological water demand, and it is an important basis for the rational allocation of water resources and ecological construction in river basin.Therefore, based on the calculation of the basin’s ecological water demand, we predict other user’s water demand and analyze the amount of water resources balance of river basin.This has great significance to the basin sustainable development and the rational allocation of water resources.Through studying the theory and method of the river ecological water demand, the Tuhai River Basin as the research object, mainly calculate the ecological water demand at present and predict the water demand in 2020 and 2030 in the Tuhai River Basin, and analyze the balance between supply and demand of water. The main contents are as following:(1) Investigate and analyze the rainfall and hydrological characteristics in the Tuhai River Basin. Flood control and drainage is the main function of the Tuhai River Basin,irrigation, landscape water as additional function. The water quality has basically reached the requirements but the level is not high, and need to increase the self-purification of water to improve it. The analysis of the characteristics of the Tuhai River Basin provide a basis for calculating the ecological water demand.(2) According to the characteristics of the Tuhai River Basin, use guarantee rate method to calculate the river basic ecological evaporation water demand, nearly 10 years minimum average monthly flow method to calculate the river self-cleaning water demand, the average sediment discharge method to calculate the sediment transport water demand, and the evaporation of rainfall deduction method to calculate the evaporation of water demand. Select the maximum among the river basic ecological evaporation water demand, the river self-cleaning water demand and the the sediment transport water demand, then adding the evaporation of water demand, and get the inner river ecological water demand. Outer riverecological water demand divided into urban ecological water demand and ecological water demand in rural areas. Use the quota method to calculate the outer river ecological water demand. The ecological water requirement is 7.93×108 m3 in the Tuhai River Basin.(3) Based on the calculation of ecological water demand, predict the water supply and water demand in 2020 and 2030 in the Tuhai River Basin. The water supply prediction include surface water, groundwater, foreign water and unconventional water; water demand forecast include the domestic water demand, industrial water demand, agricultural water demand, the urban public water and ecological water demand. And analyzes the water resources balance between supply and demand. When P=50%,75% the water deficit of Tuhai River Basin are 11.2× 108 m3,5.86 × 108 m3, the water deficient ratio are 19.66%,11.31% in2020. When P=50%,75% the water deficit of Tuhai River Basin are 13.98×108 m3,8.82×108m3, the water deficient ratio are 3.20%,16.01% in 2030.