1990—2020年三江源水源涵养能力时空变化及影响因素

Spatiotemporal variation and influencing factors of water conservation capacity in Three⁃River Headwaters region from 1990 to 2020

三江源是我国重要的水源涵养功能区,也是我国乃至东南亚地区的生态屏障,具有重要的生态战略地位。揭示三江源水源涵养能力的空间分布、变化趋势及影响因素,对于推进生态保护与修复工程,提高区域水资源供给能力和维持生态系统健康稳定具有重要意义。基于InVEST模型,定量分析了三江源区水源涵养能力的时空变化及影响因素。结果表明:草地生态系统为三江源水源涵养功能主体,年平均水源涵养量为120.04亿m^(3)。1990—2020年三江源水源涵养量呈显著上升趋势,变化速率为1.80亿m^(3)/a(P<0.05),年平均水源涵养量为163.84亿m^(3)。生态治理前(1990—2005年)水源涵养量增长速率高于生态治理后(2005—2020年)。三江源区水源涵养能力空间分布上表现出东南高、西北低的特点,显著增长面积为22.07万km2,占全区总面积的60.79%。生态治理前,降水量增加、实际蒸散量增加和实际蒸散比降低等气候变化为驱动水源涵养能力增长的主要因素;生态治理后,林、草地面积增加等土地利用/覆被变化为驱动水源涵养能力增长的主要因素。

Three-River Headwaters region is a critical water conservation area in China and an ecological barrier of Southeast Asia,which has an important ecological strategic position.It is important to reveal the spatial distribution,changing trends and influencing factors of water conservation capacity to promote ecological protection.It is also meaningful in improving the regional water supply capacity and maintaining the stability of the ecosystem.Based on the InVEST model,this paper estimated the spatial and temporal changes of water conservation capacity and analyzed the influencing factors.The results indicated that the grassland ecosystem accounted for most of the water conservation,with an average annual amount of water conservation of 12.00 billion m^(3).From 1990 to 2020,the water conservation in Three-River Headwaters region was significantly rising with an increasing rate of 0.18 billion m^(3)/a(P<0.05).The average amount of water conservation was 16.38 billion m^(3).From 1990 to 2005,the increasing rate of water conservation was higher than that from 2005 to 2020.The spatial distribution of the water conservation capacity was high in the southeast and low in the northwest.The significant growth area was 220700 km2,accounting for 60.79%of the total area of the region.Before the implementation of ecological project(1990—2005),climate changes such as increased precipitation,increased actual evapotranspiration and decreased actual evapotranspiration ratio were the main factors driving the increase in water conservation capacity.After the implementation of ecological project(2005—2020),land use/cover changes such as increased forest and grassland areas were the main factors driving the increase in water conservation capacity.