Effects Of Land Use And Landscape Pattern Change On Watershed Erosion And Sediment Yield

Land use/land cover change (LUCC) and its hydrological environment effect have received more and more attention and emphasis by domestic and overseas academia. As one of the major environmental effects which is triggered by land use change, soil erosion have been an important reason which affects regional ecological environment change, water and soil conservation of forest and meadow, as well as reservoir siltation. As a quantification and parameter of land use change, landscape pattern has become an effective approach to study soil erosion in basin scale. Consequently, it is significant to optimizing water and soil conservation and improving relationship between land and human-being that the rule of generation and delivery of basin runoff and sandy soil were explored.The northern main stream of Min River occupied very important ecological and geographical location, water loss and soil erosion has become a critical problem influencing local ecology and environment. In this paper, selecting Min River as the study area, the regional distributed hydrological model was built based on SWAT model. The ultimate objective was to study the variation of generation and delivery mechanism of basin water and sediment yield, as well as its relationship with landscape pattern. And the main research contents and conclusions were as follows:(1) Study the method of building the distributed hydrological model based on SWAT, and explain many critical procedures, such as the river extraction and sub-basin division based on DEM, the establishment and supplement of meteorological station databases, setting up of soil database, selecting simulation methods, model parameters sensitivity settings and analysis, the results output and analysis and calibration of the model. Focus on the technology and methods which were applied to the study area by using SWAT model.(2) After Zhen Jiang Guan Basin distributed hydrological model was built based on SWAT model, it was validated and calibrated by using the actual measured data from 1980 to 2005. Under the land use scenarios of 1986,1995, and 2000, ground surface runoff and sediment yield were verified. The validation and calibration results showed that the SWAT model has good applicability in the simulation of selected basin runoff and sediment yield. According to the average annual precipitation, the sediment erosion of each sub-basin under three land use scenarios was simulated through the established model, and based on the sequence of water accumulation, the net sediment yield and erosion modulus were calculated.(3) Using the software and tool-Fragstats, the landscape indicators under three scenarios of land use structure were calculated. Sab-basins were selected as samples and using regression analysis algorithm, the relationship between soil erosion yield and landscape indicators under different land use structure was explored. The landscape indicators which were more correlated to sediment yield was selected, and the linear relationships under different land use scenarios between them were identified. Eventually, the multi-element regression equation between sediment yield and landscape pattern indicators was found. According to the practically physical performance of the equation and the meanings of these landscape indicators, some theoretical references could be offered to the water and soil maintenance, improvement of water environment as well as BMP (best management practice) of landscape pattern of Zhen Jiang Guan Basin, etc.