Spatial Distribution of Water Quality Indexes and Their Response to Land Use Patterns in the Gaotan River Basin

The relationship between water quality and land use is of significance for the protection of the water environment. Here we take the Gaotan River Basin in Liangping District as the research object, and comprehensively use the spatial analysis with geographical information system(GIS), Pearson correlation analysis, and redundancy analysis(RDA) to study the ecological response of four water quality indexes of chemical oxygen demand(COD), biochemical oxygen demand in the 5 th day(BOD5), ammonia nitrogen(NH3-N), and total phosphorus(TP) on land use patterns on a sub-basin scale. The results show that land use patterns of the Gaotan River Basin have an important impact on water quality: wooded land can improve the water environment of the river; dry land, land for urban and rural housing and public facilities, and land for mining and industrial use are the main sources of COD, BOD5, and NH3-N; garden plot, land for building communications, and water areas have a weak impact on pollutants, indicating that agricultural non-point source pollution and domestics pollution in rural areas are the major cause of the deterioration of the water quality of the Gaotan River. The research results are of guiding significance to the treatment of water environment of the Gaotan River Basin.

Relationships Between River Water Quality and Landscape Factors in Haihe River Basin, China: Implications for Environmental Management

River water plays a key role in human health, and in social and economic development, and is often affected by both natural factors and human activities. An in-depth understanding of the role of these factors can help in developing an effective catchment management strategy to protect precious water resources. This study analyzed river water quality, patterns of terrestrial and riparian ecosystems, intensity of agricultural activities, industrial structure, and spatial distribution of pollutant emissions in the Haihe River Basin in China for the year of 2010, identifying the variables that have the greatest impact on river water quality. The area percentage of farmland in study area, the percentage of natural vegetation cover in the 1000-m riparian zone, rural population density, industrial Gross Domestic Product(GDP)/km^2, and industrial amino nitrogen emissions were all significantly correlated with river water quality(P < 0.05). Farming had the largest impact on river water quality, explaining 43.0% of the water quality variance, followed by the coverage of natural vegetation in the 1000-m riparian zone, which explained 36.2% of the water quality variance. Industrial amino nitrogen emissions intensity and rural population density explained 31.6% and 31.4% of the water quality variance, respectively, while industrial GDP/km^2 explained 26.6%. Together, these five indicators explained 67.3% of the total variance in water quality. Consequently, water environmental management of the Haihe River Basin should focus on adjusting agricultural activities, conserving riparian vegetation, and reducing industrial pollutant emissions by optimizing industrial structure. The results demonstrate how human activities drive the spatial pattern changes of river water quality, and they can provide reference for developing land use guidelines and for prioritizing management practices to maintain stream water quality in a large river basin.

Losses of Ecosystem Service Values in the Taihu Lake Basin from 1979 to 2010

The Taihu Lake Basin, an east-coastal developed area, is one of the fastest-growing metropolitan areas in China. Ecosystem services in the Taihu Lake Basin have been overexploited and jeopardized. Based on land-use and land-cover change （LUCC） data from 1979, 1984, 2000, and 2010, in conjunction with the adjusted ecosystem service values （ESV）, changes in ESV were analyzed in detail. Results revealed that LUCC resulted in a substantial decrease in total ESV from S3.92 billion in 1979 to S2.98 billion in 2010. The ESV of cropland decreased from $1.64 billion in 1979 to S1.34 billion in 2010, which represented a 20.28% reduction. The ESV of water areas decreased from S1.08 billion in 1979 to $0.36 billion in 2010, which represented a 65.62% reduction mainly because of a decline in water quality. In terms of annual change rate, cropland and water areas showed a sustained downward trend. Spatially, ESV declines were mainly observed in Suzhou, Wuxi, Changzhou, and Shanghai, probably due to a combination of economic progress, population growth, and rapid urbanization. The research results can be a useful reference for policymakers in mitigating ESV decline.

Spatio-temporal variation of net anthropogenic nitrogen inputs in the upper Yangtze River basin from 1990 to 2012

The net anthropogenic nitrogen input(NANI) is an important nutrient source that causes eutrophication in water bodies. Understanding the spatio-temporal variation of NANI is important for regional environment assessment and management.This paper calculated NANI in the upper Yangtze River basin(YRB), upstream of the Three Gorges Dam(TGD), from1990 to 2012, and analyzed its spatio-temporal characteristics. Over the past 23 years of the study, the average annual NANI increased from 3200 kg N km^(-2) to 4931 kg N km^(-2). The major components were fertilizer N application, atmospheric N deposition,and net food and feed N import. In the northwest high mountainous region with a sparse population, the main component was atmospheric N deposition. Fertilizer N application and net food and feed N import were concentrated in the Chengdu Plain because of the high population density and large areas of farmland. This research found that NANI increased with rapid urbanization and increasing population. The Pearson correlation results illustrated that the spatial distributions of NANI and its major components were affected by land cover/use, agricultural GDP and total population. Increasing NANI has been the major cause of the degrading stream water quality over the past 20 years and is becoming a major threat to the water quality of the TGD reservoir.