Effects of Landscape Development Intensity on River Water Quality in Urbanized Areas

Urban development and human activities have greatly changed the appearance of urban landscapes, and also affect urban river water environments. Rapidly urbanized regions in China face particularly severe pressures and challenges in alleviating degradation of river water quality. Information is needed on which indexes of landscape development intensity in rapidly-urbanized areas are the key factors affecting the quality of river water environments, and how these factors affect water quality. In order to answer these questions, this research selected six indexes belonging to three dimensions for landscape development intensity evaluation. Based on five water quality parameters of 20 rivers and the land use data of 20 small watersheds of Liangjiang New Area, Chongqing, China in 2014, this research explored the correlation between the landscape development intensity indexes and river water quality through redundancy analysis. We found that the impervious surface rate and the land average fixed asset investment are the key indexes to affect river water quality. Regulating the corresponding indexes at the urban planning and design level, as well as the decision making level, can effectively achieve the goal of improving urban river water quality. The conclusions inspire strategies in planning and design, and are helpful for government decision making to effectively protect river water environment in rapidly urbanized areas in the developing countries.

Development of the Wetland Condition Index (WCI) by Combining the Landscape Development Intensity Index (LDI) and the Water Environment Index (WEI) for Humid Regions of China

Human use and management have a marked effect on wetland from different scales; it is necessary to develop a multi-scale integrated method to assess wetland conditions. So, this research aids the development of the wetland condition index (WCI) for humid regions of China by combining two main sub-indices: (i) the landscape development intensity index (LDI), which assesses human-dominated impacts; and (ii) the water environment index (WEI), which assesses changes in water quality and phytoplankton. We measured terrain and land use in the watersheds of wetlands using remote imaging data with geographic information systems (GIS) software. Also, we monitored the physical and chemical variables of the water bodies of 27 wetlands in urbanized and moderately urbanized areas in Nanjing City of China for this study. There were significant inconsistencies between the city’s level of development and the values of the WCI and its sub-indices. The WCI of urbanized areas was better than that for moderately urbanized areas, and the sub-indices LDI and WEI were only slightly correlated. In other words, wetlands with a low LDI value did not necessarily have a low water environment index value. Due to wetland restoration and human management activities, integrating the LDI and WEI is increasingly necessary for wetlands in urbanized areas than for moderately urbanized areas. This method could guide the design of wetlands to optimize their qualities and benefits to residents and reinforce wetland conservation.