River Watershed Land Use And Water Quality Changes And Their Relationships

Land use/land cover change (LUCC) and Biospheric Aspects of Hydrological Cycle (BAHC) are two core researches of International Geosphere-Biosphere Programme (IGBP). The land use change, as an artificial system interference, is the second major boundary condition that affects the hydrological processes directly or indirectly. The land use change tends to strengthen the soil erosion and affect all the links of the hydrological cycle so as to aggravate the non-point source pollution in the watershed. Consequently, there was an important practical significance for improving the water quality and access to sustainable development of the ecological environment to research the dynamic change of the land use and its influence on water quality in the watershed.This paper used geographic information systems theory and method to deal with the data of TM image, DEM data, water quality data, statistical data and the survey data. By using of Markov matrix, land use dynamic model and land use degree, the characteristics of land use change in Feng river basin from1988to2009were fully analyzed. Then, the correlation between land use structure of different buffer zone and water quality indexes is fully analyzed. Finally the reasonable measures for Feng river basin development are put forward in the study.Through this research, conclusions were as follows:(1) The forest land and cultivated land were the main land use types in the study area, with the total proportions of90%. The proportion of the grass land, water and other land were very small. From the year of1988to2009, the change of each land use type has taken place. The constructive land presented increasing trend from29.381km2in1988to143.914km2in2009, with the annual increase of5.454km2. The cultivated land presented decreasing trend all the time from678.614km2in1988to506.218km2in2009, with the annual decrease of8.209km2. The forest land area increase from732.752km2in1988to792.148km2in2009, with the annual increase of2.828km2. The grass land, water and other land in study area didn’t change obviously from1988to2009.(2) From the perspective of land use, the fastest increase of land use from the year of1988to2009was constructive land with the increase speed of18.563%/a, and the fastest decrease of land use was the other land and cultivated land, with the decrease speed of2.126%/a and1.201%/a respectively. From1988to2009, the main land use change was cultivated land into forest land or constructive land.(3) From the land use degree, the land use in study area from1988to2000was in an adjustment or recession period. The land use degree increase from248.01in2000to254.08in2009showed that the study area was in the development of land use. From the limit degree of400, the study area has reached a status of high level development so far.(4) The water quality of Feng river experienced three stages of polluting heavily, polluting maintain and water improvement. The water quality of middle to lower part in Feng river improved greatly from2005to2009. It was mainly because of the environmental protection work to reduce the industrial pollution source in the basin by government department.(5) The cultivated land、 constructive land and other construction land were positively correlated with water quality indexes BOD5、CODMn and NH3-N, while the forest land were negatively correlated with these water quality indexes. It showed that the land use in the river basin had great impacts on water quality parameters.The cultivated land、forest land and constructive land showed negative effects on water quality, and were the dominant factors for river pollution in Feng River Basin.The forest land exhibited a significant positive relation with water quality. The distance of100m showed the most significant correlation. As the distance increased, the correlation between water quality and land use change gradually decreased. All these analysis told us that the land use pattern was the main reason to the water pollution in Feng River Basin.(6) The treatments for the non-point source pollution of Feng river basin are divided into two aspects. One aspect is to control the pollution source. The main treatments are to reduce the use of the chemical pesticides and fertilizers, strengthen the examination of the soil and fertilizers, avoid the farming practices close to the river basin, reduce the surface debris, improve the cleaning method, improve cleaning efficiency, keep the cleanness of the ground, process the rural junk centrally, retrieve the feces and adopt the scientific feed way of the livestock. In addition, the relevant departments should strengthen the management of upstream tourism, plan the tourist facilities reasonably, calculate the environmental capacity, strengthen the propaganda and education, and improve health habits of the local residents. The second aspect is to control the spread of pollutants. The main treatments are to develop the area of reforestation and grassland, carry out the wetland restoration project. In addition, we should process eco-environment construction, plan the use of urban land reasonably, reduce the ratio of impermeable pavement, and increase the infiltration of town surface.