Investigation On Temporal-spatial Change Of Water Environment Quality And Its Driving Forces In Hunan Province

Hunan Province is a typical red soil hilly region located in South China, where water resources are abundant. Due to the rapid development of society and economy, water quality in Hunan province was getting more serious and a water crisis was emerging. The Xiangjiang River, Zishui River, Yuanshui River, Lishui River, and Dongting Lake were very important water bodies in Hunan Province. Based on continuous monitoring data of Xiangjiang River, Zishui River, Yuanshui River, Lishui River, and Dongting Lake from 1990 to 2000, the study examined the temporal-spatial variation of water quality in Hunan Province by adopting comprehensive WQI (Water Quality Index), and utilizing statistical methods to investigate the relationships between economic development and water pollution by EKC (Environmental Kuznets Curve) hypothesis. The results of temporal analysis show water pollution was becoming increasingly worse. The results of spatial analysis indicated that the water environment in the west province was better than that in the east. By comparing the water quality in different watersheds and districts, it was revealed that the Xiangjiang River watershed of the four main watersheds and Zhuzhou City in this watershed were the worst, for these areas were the most developed regions in Hunan Province.In the study, multivariate statistical methods including factor, principal component and cluster analysis were applied to analyze surface water quality data sets obtained from Xiangjiang watershed, and generated during 7 years (1994-2000) monitoring of 12 parameters at 34 different profiles. Hierarchical cluster analysis grouped 34 sampling sites into three clusters, including relatively less polluted (LP), medium polluted (MP) and highly polluted (HP) sites, and based on the similarity of water quality characteristics, the watershed was divided into three zones. Factor analysis/principal component analysis, applied to analyze the data sets of the three different groups obtained from cluster analysis, resulted in four latent factors accounting for 71.62, 71.77 and 72.01% of the total variance in water quality data sets of LP, MP and HP areas, respectively.With the support of GIS and the principle of landscape ecology, the method of Landscape Index was used to analyze the spatial pattern of land use of Xiangjiang River basin in 2000. The method can diagnose the rationality of the land-use, and then the government could make a better plan on land use and improve the ecological environment.The change of land-use pattern is the one of the main causes of the non-point source pollution. Taking a typical watershed in hilly red soil region-Liuyanghe Watershed as a case study, combined with the land-use pattern of 1980, 2000 and 2005, soil and precipitation data, under the support of RS and GIS, the dynamic change of land-use pattern was analyzed and the long term average pollution loads were estimated using L-THIA model. Then the dynamic change of distribution of non-point source pollution was analyzed. The results showed there was a significant trend of transforming from forest and glass land to urban, agricultural and rural residential areas,and from agricultural land to urban area. The agricultural areas increased from 13.75% to about 20% of the total watershed, and the urban and urban residential areas were changed from 1.34%,0.1% to 2.56%,0.8%, separately, Which made the sensitive areas of non-point source pollution were expanding, and the pollution degree is more and more seriously from 1986 to 2005. In order to alleviate the impacts of land-use change, Liuyanghe watershed was divided into two prevention zones, based on the distribution of non-point sources pollution and pattern of land-use, where different measures should be taken. It was useful for in a decision-making in land-use planing and watershed management.According to the results above, with rapid economic development in Hunan Province, the water environment was getting worse; the point source pollution is the most important factor affecting the water environment, while the non-point source pollution was becoming increasing serious.