基于PLUS-InVEST模型的“两湖一库”流域水质净化时空演变

Spatial-temporal Evolution of Water Quality Purification in“Two Lakes and One Reservoir”Basin Based on PLUS-InVEST Model

探讨土地利用变化所引发的水质净化演变,对于保护和改善水质,实现可持续发展具有重要意义。以“两湖一库”流域为例,运用PLUS(patch-level land use simulation)模型和InVEST(integrated valuation of ecosystem services and tradeoffs)模型生态系统服务水质净化模块,基于2000年、2010年和2020年土地利用数据,模拟流域在未来自然发展情景和生态保护情景下的用地类型时空格局变化以及水质净化特征。定量揭示土地利用变化与水质净化功能的响应关系。结果表明:“两湖一库”流域土地类型以耕地为主,2030年在自然发展情景下耕地、林地、草地面积呈下降趋势,建设用地呈上升趋势,生态保护情景可有效保护流域耕地、林地等空间分布和面积;“两湖一库”流域TN、TP输出量以低强度输出为主,2000—2020年TN输出量先增加后减少,TP输出量逐年增加,水质净化能力呈稳中变好的趋势;2030年自然发展情境下TN输出量持续减少,TP输出量呈向上浮动,生态保护情景下TN、TP输出量较自然发展情景下减少,生态保护情景可以增加水质净化能力。生态用地类型可以有效截留N、P进入水体,生态保护情景下有效降低生态用地类型的变化速度,减少TN、TP的输出量,“两湖一库”流域未来规划中应增加生态用地的占比,增加土地类型对TN、TP的截留能力。

Exploring the evolution of water quality purification triggered by land use change is important for protecting and improving water quality and achieving sustainable development.Taking the“Two Lakes and One Reservoir”basin as an example,the patch-level land use simulation(PLUS)model and the integrated valuation of ecosystem services and tradeoffs(InVEST)model ecosystem service water quality purification module were used to simulate changes in the spatial and temporal patterns of land use types as well as the characteristics of water quality purification of the basin under future natural development scenarios and ecological protection scenarios based on the land-use data for the years 2000,2010 and 2020.The response relationship was quantitatively reveal between land use change and water purification function.The results show that the land type of the“Two Lakes and One Reservoir”basin is dominated by arable land,and in 2030,the area of arable land,forest land and grassland under the natural development scenario shows a decreasing trend,and the area of construction land shows an increasing trend,and the ecological protection scenario can effectively protect the spatial distribution and area of the basin’s arable land and forest land,etc.The TN and TP outputs of the“Two Lakes and One Reservoir”basin are dominated by the low-intensity outputs,and the outputs of TN increase firstly and then decrease,and TP outputs increase year by year during the period of 2000—2020.From 2000 to 2020,TN output first increases and then decreases,TP output increases year by year,and the water purification capacity shows a steady trend.In 2030,TN output continues to decrease under the natural development scenario,and TP output shows an upward fluctuation,and TN and TP output under the eco-protection scenario is reduced compares with that under the natural development scenario,and the eco-protection scenario can increase the water purification capacity.Ecological land types can effectively intercept N and P into the water body,and the ecological protection scenario effectively reduces the rate of change of ecological land types and reduces the output of TN and TP. The future planning of the “Two Lakes and One Reservoir” basin should increase the proportion of ecological land, and increase the ability of land types to intercept TN and TP.