The Impact Of Water Resource Change On Ecological Environment At Watershed Scale

In the world, water is the greatest natural resource and also is distributed most widely, meanwhile is utilized diffusely. In the Earth, water distribution is not uniform, the annual and seasonal precipitation and runoff from different place are very different too. As well, lots of factors affect water's temporal and spatial change trend. Furthermore water is the link what contact with all of the ecosystems, so, in natural environment, water for the survival and development of living beings and humankind is decisive significance. Therefore, the change of water resource on the basin will certainly have great impacted to ecological environment.Taking the Hanjiang River Basin (in Hubei province) for example, based on these data of runoff and precipitation on the basin in recent ten years, analyzing change trend of Hanjiang basin precipitation and runoff by using the Mann-Kendall trend test to reflect the water resource change on Hanjiang River Basin. Through studying the transmission of moisture and heat between soil-vegetation-atmosphere, the BATS (Biosphere Atmosphere Transfer Scheme) model is used to simulate the thunder storm and flood events on the Hanjiang River Basin in July,2010. And the inherent relationships among runoff, soil texture, soilmoisture content and vegetation are exposed via the simulation of water exchange between land and atmosphere. Results show that:(1)At the a=0.1 significance level, runoff and precipitation in the middle and lower reaches of the Hanjiang River both showed decline; (2)Through Mann-Kendall rank inspection method analysis of runoff and precipitation in the middle and lower reaches of the Hanjiang River statistical variation of the trend, we can see that runoff and precipitation trend changes are positively relation, and explain that the Hanjiang River Basin in the influence of precipitation on runoff is very important; (3) Runoff and precipitation of Hanjiang River has achieved significant decline, the main reason summarized as climate change and underlaying surface properties change; (4) Soil texture, air force input and runoff exponential on runoff formation produce a significant impact. When the soil without frozen, this paper argues that BATS model runoff will index into and topography fluctuation related a parameter, its exact value decision by the local terrain conditions; (5) For such plain region in Xiantao city, runoff and soil texture, root layer of soil moisture and deep soil moisture are positively related, and the vegetation coverage and soil color is inversely related, but the influence of soil color to the runoff is very small.I hope that this research can provide a certain reference to the rational use of water resource and the protection of ecological environment in the Hanjiang River Basin.