Abstract:

The relationship between land use/land cover(LULC) and water quality is one of the important components of land use environmental effects research. The type, size and distance of different land use types to water bodies are usually studied in a manner relating them to water quality. With Landsat Thematic Mapper(TM) images and the water qualities in 11 monitoring sections, this paper analyzed the relationship between land use and water quality parameters(DO, CODMn, NH3N) in Chishui River basin on the buffers and subwatershed scale，and made multiple regression model of water quality parameters. Based on Geographic Information System (GIS) spatial analysis, round types of contributing zones were developed around these monitoring sections. And based on GIS hydrology analysis, the subwatersheds were segmented. Then, six types of land use types were extracted from TM images in 2009. On the basis of water quality parameters, the correlation relationship between water quality and land use pattern over different contributing zones was examined. Correlation analysis showed that, from round types of buffers to subwatersheds scale, the correlation of construction land and NH3N increased form significant positive correlation to highpositive correlation, and the correlation coefficient reached 0.836. The correlation of construction land and CODMn increased form positive correlation to significant positive correlation, and the correlation coefficient reached 0776. The correlation of cultivated land and CODMn increased form significant positive correlation to highpositive correlation, the correlation coefficient reached 0913.The correlation coefficient of cultivated land and NH3N increased to 0782. The correlation of cultivated land and DO increased form negative correlation to significant negative correlation, and the correlation coefficient was 0.609. On the buffer scale, the forestland exhibited negatively correlated with CODMn and NH3N，and the degree of correlation increased with the increase of buffer radius. While on the subwatersheds scale, the forestland exhibited significant negative correlation with NH3N and highly negative correlation with CODMn, the correlation coefficient reached 0.673 and 0.822, respectively. All of these showed that the land use patterns in Chishui River basin had great impacts on surface water quality, and construction land and cultivated land gravely influenced the water quality in Chishui River basin. City domestic sewage, industrial sewage and agricultural nonpoint source pollution hosted on these land use types are the important sources of water pollution. Nevertheless, the shrubgrass and forestland showed positive effects to some extent. Generally, the correlativity between land use and water quality parameters was consistently on both buffers and subwatershed scale in Chishui River basin, while it was exhibited more significant on subwatershed scale .On buffers scale, we cloud analyze the effect of the distance between land use types and the river on water quality. However, the natural attributions of subwatershed cloud be taken into account on subwatershed scale. The research could provide both critical information in sustainable land use practice for water resource conservation for Chishui River basin, and a methodological reference for analogous study