1980—2016年三江源国家公园水源供给及水源涵养功能时空变化研究

Spatial and temporal changes of water supply and water conservation function in Sanjiangyuan National Park from 1980 to 2016

为实现三江源国家公园水源供给及涵养功能评估,服务区域生态服务价值估算,基于InVEST模型,利用1980-2016年期间共7期土地利数据,结合气象数据,土壤数据,地形数据等,评估了三江源国家公园水源供给及水源涵养量的时间变化特征与空间分布状况。结果表明:1)1980-2016年三江源国家公园年降水呈不显著增加趋势;潜在蒸散、实际蒸散显著增加。在此影响下,园区产水量及水源涵养量总体呈不显著增加趋势。在不同年代,园区水资源总量经历了骤降-好转-略微降低的变化过程。降水量与实际蒸散量对园区产水量及水源涵养量影响最为显著。2)园区产水量及水源涵养量空间分布趋势一致,呈由北向南先减少后增加的变化趋势。这种空间差异主要由降水差异及地表覆盖特征引起的蒸散差异引起。3)在极端降水条件下,园区产水量及水源涵养量的数量和空间分布差异十分显著。长江源园区生态水源对降水变化的响应最为敏感。

Spatial and temporal changes of water yield and water conservation in Sanjiangyuan National Park were evaluated based on the InVEST model using seven periods of land use data from 1980-2016, meteorological data, soil data, and topographic data. The main conclusions were as follows:(1) The annual precipitation in Sanjiangyuan National Park showed an insignificant increasing trend from 1980 to 2016, while the potential evaporation and actual evaporation increased significantly, with increase rates of 14.46 mm/10 a and 5.95 mm/10 a, respectively. In this context, the water yield and water conservation in Sanjiangyuan National Park showed an insignificant increasing trend, with an annual average value of 118.17 mm and 45.04 mm, respectively. The total water resources in Sanjiangyuan National Park experienced a process of drastic decrease-increase-slight increase. Precipitation, actual evapotranspiration, and actual evaporation ratio(actual evaporation capacity) were the main climatic factors affecting water yield and water conservation.(2) The spatial distribution of water yield showed a trend of decreasing and then a trend of increasing from north to south. Among the three parks, Precipitation was highest in Lancangjiangyuan Park.This park also had relatively high vegetation cover. Hence, the water yield quantity was relatively higher. The water yield in Huangheyuan Park showed an obvious increasing trend from north to south due to the climate difference. Changjiangyuan Park had the lowest precipitation of the three. However, the evapotranspiration coefficient of bare land and desert was low and the actual evaporation was also low. Hence, water yield in this region was slightly higher than that of Huangheyuan Park. The spatial distribution of water conservation was consistent with that of water yield and also affected by topographic indices. On the whole, the spatial distribution of water resources was mainly caused by spatial differences of precipitation and evapotranspiration, which are closely related to land cover and soil characteristics.(3) The amount and spatial distribution of water yield and water conservation in the park varied significant in extreme precipitation conditions. In Huangheyuan Park and Lancangjiangyuan Park, the water resources in a dry year were 40%-45% those in a wet year and 58%-75% of the annual average values. In Changjiangyuan Park, the water yield in a dry year was only 29.08% that in a wet year and less than half the annual average value. Water conservation in a dry year was 30.1% that in a wet year and 43.13% of the annual average value. Thus, we infer that the ecological water source in Changjiangyuan Park is more sensitive to change of precipitation. The ecological risk of this region is relatively higher, and it should be given considerable attention.