Distributed Simulation And Evolution Law Of Water Cycle In The Weihe River Basin Under Changing Environment

The evolution law of water cycle under changing environment and attribution analysis is the hot and hard issue of the hydrology. According to the literatures, there are two types changing environment:climate changes and human activities. The influences of the human activities on water cycle are enhanced recently. The processes of the water cycle affected by human activities have dual characteristic, which means that the water cycle is driven by natural and social factors.In this paper, the WEP-L model is improved on the basis of natural-social dual water cycle theory. The improved aspects are watershed subdivision processes and socil water cycle module. The improved WEP-L is adoped to build the distributed hydrological model on Weihe River Basin. At last, the evolution law of water cycle under changing environment and attribution analysis is explored. Here are the contents:(1) The WEP-L model is refactored. The social water cycle module of WEP-L is improved to heighten the simulated precision of water fetching, water consuming and water draining.(2) The improvement of the drainage network extraction. The underlying problems, which are hiden in the drainage network extraction process, are investigated. In order to solve these problems, a new algorithm is promoted, which could automatically deals with these questions.(3) A new subwatershed coding method is presented for the watershed subdivision. It focuses on the problems of the unfitness of the existing method for meeting the new demands, which are dealing with multi-way confluence situation and locating the upstream and downstream relationship quickly etc. The new coding method could fullfill all the new demands of the distributed hydrological models.(4) The evolution law of the Weihe water cycle is investigated, which is based on the different scenes emulational simulation. The main considered water cycle factors are evapotranspiration, infiltration, surface runoff generation, ground water recharge, water exchange between ground water and river water, and streamflow. The main considered changed environments are meteorologic factor, soil and water conservation, agricultural water use, and industrial&living water use.(5) A new attribution analysis method is proposed, which is based on the distributed hydrological simualtion and could deal with multi-factors simultaneously. Using this method, it could calculate the contribution of each factor and make sure that the sum of all the contributions just equals to the muti-factors contribution. Taking Weihe River basin as example, the multi-factor contributions before and after1980is calculated, which are meteorologic factor, soil and water conservation, agricultural water use, and industrial&living water use.The main innovations of this paper are:(1) three methods, which are drainage network extraction, subwatershed codification and multi-elevation contribution analysis;(2) constructing the Weihe WEP-L distributed hydrologic model for the evolution law of water cycle. This research is of great importance not only resolving the issues on watershed subdivision, but also making it possible for the multi-elevation contribution analysis on the water cycle. Meanwhile, this paper is a supplement of the natural-social dual water cycle theory.