A Study On Influences Of Landuse Change To Huangqian Watershed Based On SWIM Model

For developing economy, Huangqian Watershed developed economic forest, which leads to the landuse type changing. Studying on the landuse changes and runoff relation is great significance for resources planning, management and sustainable development. This research has chosen Huangqian watershed as the study region. Remote sensing (RS) images of two typical periods (2005,2008) are the main information sources. Based on"3S"technology (RS,GIS,GPS) , through the methods of man-machine interaction interpretation and investigation in the open air, studied the landuse pattern and dynamic in Huangqian Watershed; Soil and Water Integrated Model (SWIM) was employed to simulate the effects of land use change on runoff and evaluate the contribution of land use change and climate change to runoff change. And the main results are as follows:1. The present situation characteristics and spatial dynamics of landuse in Huangqian Watershed are explored.The present situation characteristics of landuse are grasped.The main landscape pattern types were shelter forest and economic forest in Huangqian Watershed in 2008. The shelter forest area is 144.78km~2, the proportion is 49.2%. The economic forest area is 105.06km~2, the proportion is 35.7%. The area of farmland, construction land, water, unused land is very small.The characteristic of spatial dynamics of landuse is that: from the channel to the top of the mountain is water, farmland, economic forest, shelter forest; The construction land is distributed both of the channel, the unused land is distributed in shelter forest sporadic. The temporal and spatial dynamics of landuse are exploredDuring 2005 to 2008, the area of economic forest, unused land, construction land and water are increased; the shelter and the farmland are reduced.The distribution of original forests are the only by both sides in the gully patchy distribution into disorderly upward along the hillside in the distribution of the ring from the original trends, town village along the channel sporadic shape distribution of change to show the channel distribution and slice the land for traffic significantly more ribbons of arable land to channel distribution trend within shrink, distribution trend in slope protection by the slopes of mount upper cut, did not use the land in the spatial distribution without change.2. Analysis of land use changes on the influence of the runoff in Huangqian Watershed. Huangqian Watershed is divided into 23 and river sub basin, 328 hydrological unit (HRU). The largest and smallest sub basin is 28.69 km~2, 1.86 basin km~2. The SWIM model can simulate runoff well in the Huangqian watershed, with an efficiency of 0.53,for the calibration and 0.51 for the validation period. The relative error are -15%and-11%, respectively.Huangqian Watershed of the soil is thin, the runoff is mainly surface runoff. Shelter forest compared with economic forest had greater ability to store the precipitation with complex monitoring structure. Simulation results following:(1) The shelter and economic forest influence on the runoff with the same vegetation coverage.Through the simulation, the vegetation coverage is certain limits, when the vegetation is higher, the runoff is smaller. If the vegetation went to a range, the vegetation coverage is not influence on the runoff, and the coverage is marginal value. The marginal value of the economic forest is 45-60%, the shelter forest is 60-75%. The greater vegetation the ability of regulating runoff is much stronger.(2) The influence on runoff with the changes of the landuse and the vegetation Change the shelter into economic forest with the biggest area and vegetation coverage 30-45%, and other conditions do not changed. The result is that when changing the economic forest into shelter forest, the runoff reduced110..3thousand m~3, comparing the economic forest with vegetation coverage 45-60% is smaller 112.7thousandm~3.3. Proposals of landscape ecological planning in Huangqian Watershed was proposed In order to realize the construction of ecological river and the economy of the basin, improve water basin of non-point pollutant reducing the effect, increase inland river basin of the reservoir area and the conservation of water supply in guarantee reservoir water and the quality at the same time, the development of basin economy in the basin, of land use planning for:Change slope as 25-35°slope of 9.65 km~2 forests and 15-25°slope surface 39.38 km~2 economic forest for shelter forest; Adjust vegetation coverage development land use and species diversity, reasonable and fully utilized river resources; According to the distribution of Yellow River terrain before characteristics of the study area, on divisional division management.