Abstract
Water yield is of great importance to the balance between supply and demand of water resources. The provision of freshwater for Dali is estimated and mapped in 1988, 1995, 2000, 2005 and 2008, using the Integrated Valuation of Environmental Services and Tradeoffs (InVEST) modeling toolset. The stability of water yield’s spatial variation is analyzed by a sorting method. The factors are explored which lead to the change in the relative water yield capacity. The yields at five points in time are compared, and the result of which shows a sharp fluctuation. The water yield curve is of a similar waveform as precipitation. An obvious and relatively stable spatial variation appears for water yield. The highest water yield areas are mainly located in the area where the elevation is high and both the elevation and the slope changes are large, and the main land uses are Shrub Land and High Coverage Grassland. The lowest areas are mainly in the eastern part of Erhai or the surrounding area. Precipitation, construction land expansion and the implementation of policy on land use are the three main factors which contribute to the change of the relative water yield capacity during 1988–2008 in Dali. In the study area, the water yield appears highly sensitive to the change in precipitation. The elasticity coefficient is calculated to illustrate the sensitivity of the water yield to the precipitation. When the elasticity index is larger, the risk of natural disaster will be higher.
Highlights
Water yield is an ecosystem service [1], which plays a basic role in farming, aquaculture, the processing industry, quality of life for humans and ecological protection
Because the administrative region is usually adopted as a unit in policy implementation and economic activity, in this paper, the administrative boundary replaces the watershed boundary to delineate the scope of the study, which facilitates analyzing the direct impacts of human activities
It is assumed that the water yield of each sub-basin will vary with precipitation, temperature and other factors, but the relative capacity of water yield among sub-watersheds will not change in the absence of interference, because the spatial structure of the geographical environment has had consistent strong stability over time
Summary
Water yield is an ecosystem service [1], which plays a basic role in farming, aquaculture, the processing industry, quality of life for humans and ecological protection. Land cover [3] caused by human activities are major factors leading to changes in water yield. Because the administrative region is usually adopted as a unit in policy implementation and economic activity, in this paper, the administrative boundary replaces the watershed boundary to delineate the scope of the study, which facilitates analyzing the direct impacts of human activities. This is vital as, due to the incomplete watershed, the water yield in this paper characterizes the water production capacity of the ecosystem in the study area, rather than the runoff in the region. Because of its ease of operation and data acquisition, the model has been applied to several sites and decision contexts [2,11], and has been introduced and promoted in different watersheds in China [10,12,13]
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