| The wide distribution of wetlands in hilly areas south of Yangtze River contributes to multipond wetland landscape. The pond wetland is important to adjust rainfall runoff and improve water quality. However, the wetland landscape structure and pattern in southern hilly areas has changed dramatically due to the process of rapid urbanization and human activities. As a result, it influenced the ability of water,such as adjusting runoff and purifying water quality. Therefore, it has brought a significant theoretical and practical importance to explore the relationship between the wetland landscape pattern and water environment in wetland landscape planning and water environment protection. From the perspective of landscape ecology, geography and environmental science,using the water environment as a check point,Qixiang River watershed was selected as a typical case study area. Based on the remote sensing in 2015 and water environmental data monitored in April, May, June 2015, we used RS,GIS,RDA analysis and correlation analysis to study the wetland landscape structure and pattern, water environment and the relationship between them. The text made some advice on protection and rational utilization of wetland. The main research findings include:(1)Water quality and water hydrology were influenced by rainfall intensity and they had some discrepancies in different geographical spatial units. From the upstream to the downstream, large rainfall intensity had the most impact on water level. Also moderate rainfall intensity had more impact than small rainfall intensity.Large rainfall intensity influenced water level significantly in the upstream and midstream but moderate rainfall intensity and small rainfall intensity were on the contrary. In the downstream, the greater the rainfall intensity, the greater the water level change.The water quality was generally poor in Qixiang River watershed and it was primarily contaminated by nitrogen. The degree of eutrophication was serious. Water quality indicators were poor, basically in the Grade ??? standard. The water quality was influenced by rainfall intensity significantly, especially Turbidity. With the increase of rainfall intensity, the river water quality became gradually poorer.(2)The wetlands were mainly river wetland and lake wetland in Qixiang River watershed. The wetland landscape structure and pattern in different geographical spatial units had obvious discrepancies. Qixiang River was 17.8 kilometers long and had little tributaries. The 842 lake wetlands mainly distributed in low-lying areas on both sides of the river. The wetlands focused on the upstream and midstream. From low flat area to high steep area, the percentage of wetland area became smaller and the distance to the river became longer. The shape of wetland became more regular. In addition, the degree of fragmentation, separation and physical connectivity reduced.(3)The wetland landscape structure and pattern in different geographical spatial units and rainfall intensity appeared to have great influence on river water quality as well as water hydrology. The low flat area influenced the river water quality significantly. COHESION influenced the water quality most under moderate rainfall intensity and DISTANCE was the key factor under large rainfall intensity in low flat area and secondary flat area. Under small rainfall intensity, DISTANCE had the greatest influence in low flat area and COHESION was the key factor in secondary flat area. In high flat area, DISTANCE had more influence on water quality than other landscape indexes. With the increase of rainfall intensity, the influence became stronger. In moderately steep area and high steep area,SH_MN influenced the water quality most under small rainfall intensity while IJI influenced the water quality most under moderate rainfall intensity and large rainfall intensity.The low flat area had the greatest influence under all the three types of rainfall intensity. With the increase of rainfall intensity, the influence got stronger in all geographical spatial units. PLAND and SH_MN were the key factor.(4) The wetland landscape structure and pattern in low flat area was vitally important to water quality so it needed rational allocation during the process of urbanization. At the same time, controlling the point source pollution and the area of impervious surface in urbanized area would sustain the river water environmental health. |
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