Research On The Hydrological Effect Of Land Use/Cover Change In Dongjiang River Basin Under Gradient Development

Under the influence of intensified human activities and climate change,the system of water resources and environment in many basins have changed significantly,and varities of problems such as water ecological degradation,water shortage thus have been brought up.Since these problems have seriously slowed down the development of economy,to explore the economic and social development to intimidation mechanism of hydrologic process is an important and scientific foundation work as well as an urgent task.Taking the development of city gradient under the changing hydrological environment as an access point,this research attempts to study the evolving rule.Dongjiang River Basin,of which the natural environment has been undergoing severe changes,was chosen as the studied area in this research.Remote sensing data,field investigation and historical materials are also applied in the research.Based on GIS technique and Hydrological Simulation Program-Fortran(HSPF),response of runoff towards land-use variation was studied.The impacts that different regions have on the runoff were analyzed by selecting three control points on the upper,middle and lower reaches.In this research,the main content and results are as follows:(1)By processing the data of meteorology,hydrology,soil,etc.,HSPF hydrology model of Dongjiang River Basin has been constructed as well as the model of database group of Dongjiang river basin has been built.The flow data in Bolton hydrological station has been used to test and calibrate the HSPF model.The result comes with the error offlow simulation less than five percent that the HSPF model can easily met the requirements from both hydrology and water quality simulation.(2)In purpose of studying the influence on runoff from land use or land cover,the process of runoff in different land use scenarios of 1980,2000,and 2008 in Dong jiang river basin has been simulated with the HSPF model,the result shows that in May and June 2008,the average runoff increased by 236 million compared with that in 1980.(3)Three control points of Fengshuba,Heyuan and Boluo in Dongjiang River Basin were chosen to simulate the process of runoff in land-use scenario of 2008 with the HSPF model.And runoff depth on the upper,middle and lower reaches were simulated to analyze the hydrological effect in different areas under the gradient development.As shown in the results,the gradient development has significant influence on the annual runoff depth in different regions of Dongjiang River Basin,and the annual runoff depth in the lower reaches is significantly higher than that in the upper and middle reaches.In addition,the gradient development has a significant influence on the monthly runoff depth of Dongjiang River Basin,and the mean monthly runoff depth of the upper,middle and lower reaches is 76.18,80.59 and 140.69 millimeters respectively,showing an obvious gradient relationship.Compared with the dry season,the hydrological effect of gradient development in flood season is more significant.In general,runoff depth in the lower reaches is significantly higher than that in the upper and middle reaches during the flood process.