都江堰市水源涵养功能空间格局

水源涵养是生态系统的重要服务功能之一.识别水源涵养重要区对于制定水源保护规划,落实陆域-水域综合保护,防治水体污染,保障区域用水安全具有重要意义.以2008年四川都江堰市为研究范围,采用生态系统服务功能综合权衡工具-Integrated Valuation of Ecosystem Services and Tradeoffs(InVEST)中的水源涵养模型对县域生态系统的水源涵养功能进行了空间制图,然后采用综合指数法将水源涵养功能与植被减洪能力和水源地保护区进行叠加计算水源涵养重要性指数.结果表明:尽管汶川地震导致都江堰市域部分地区水源涵养功能降低,但都江堰市水源涵养功能整体仍然较高,部分地区多年平均水源涵养量超过200mm/a.都江堰市的水源涵养极重要区面积为421km2,占全市总面积的34.9％,远大于目前县域的水源保护区面积,未来应进一步加强对这些极重要区的保护,以保证本市以及成都平原的供水安全.水域涵养功能及其重要性都存在较明显的空间分异,大致呈现由西北向东南减少的趋势,水源涵养重要性与水源功能的分布密切相关,但又不完全一致.因此,在县域尺度上采用服务功能空间化评估结果进行重要性评价能够比较精细地反映生态系统水源涵养重要性的空间差异.但该方法还需要将人类用水需求进行空间表达,与本文的方法进行结合,以更准确反映水源涵养重要性的空间分异.

Spatial Pattern of Water Retetnion in Dujiangyan County

Evaluation of water retention importance of the ecosystem is one of the key elements of ecological assessment and planning. The importance of water retention not only reflects the level of water retention function of the ecological system, but also reflects the water demand for human life and production on a regional scale. Identification of a water retention importance area is of great significance for the establishment of water source protection planning, the implementation of integrated protection of land and water areas, water pollution treatment, and the protection of regional water resource security. In this paper, the assessment of water retention importance of Dujiangyan where there was hit by earthquake in 2008 was carried out by using the InVEST(Integrated Valuation and Tradeoffs of Ecosystem Services) model on a county scale, then the water retention importance was assessed by using the composite index method in combination with the flood mitigation capacity of vegetation and the distribution of water source protection area. The results showed that although water retention functions in some places of Dujiangyan were impaired because of Wenchuan earthquake, water retention functions in Dujiangyan City as a whole are still high. In some areas, the average amount of water retention is over 200mm/a. The very important water retention area of Dujiangyan covers an area of 421km², and accounts for 34.9% of the total area of the city, which are much larger than the city's current water source protection area. Therefore, the protection of these very important areas should be further strengthened in the future, so as to ensure the water resource security of the city and the whole Chengdu Plain. The water retention functions and their importance show relatively obvious spatial variations, generally displaying a decreasing trend from northwest to southeast. Water retention importance is closely related to the distribution of water retention functions, but the case is not exactly the same. Therefore, on a county scale using the results of assessment of service function space to evaluate the importance can precisely reflect the spatial difference of water retention importance of ecosystems. However, this method can be improved by mapping the water demand of human.