气候变化和人类活动对渭河流域蓝水绿水影响研究

以渭河流域为研究对象,探讨了1980~2009年气候变化和人类活动对蓝绿水资源的影响。结果表明：① 研究时段内,在气候变化和人类活动的共同影响下,蓝水流、绿水流和绿水储量分别下降了23.56 mm/a、39.41 mm/a和17.98 mm/a,中北部的蓝水流和绿水储量呈现增加的趋势,流域上游地区的绿水流呈现下降趋势。② 归因分析表明,蓝水流、绿水流和绿水储量在气候变化驱动下分别下降了13.17 mm/a、44.99 mm/a和22.79 mm/a;土地利用/覆盖变化则导致蓝水流和绿水流分别减少0.42 mm/a和0.37 mm/a,绿水储量增加了0.79 mm/a;而农业灌溉使蓝水流减少了9.97 mm/a,绿水流和绿水储量分别增加了5.95 mm/a和4.02 mm/a。③ 气候变化导致研究区东南部绿水系数呈现增加趋势,而泾河流域绿水系数呈现减小趋势。同时,土地利用/覆盖变化使得东南部的一些子流域绿水系数呈减小的趋势,而在加入农业灌溉情景后,平原地区灌区绿水系数呈明显的上升趋势。

Impact of Human Activities and Climate Variability on Green and Blue Water Resources in the Weihe River Basin of Northwest China

It is widely recognized that human activities and climate variability are two important factors that affect water resources and freshwater ecosystems. Previous evaluation work on water resources has predominantly focused on the qualification of blue water flow. Meanwhile the green water flow, another important part of water resources for the healthy development of rivers and basins, is seldom discussed. In arid and semi-arid regions, the analysis of spatiotemporal distribution of blue and green water resources under human activities and climate variability is critical for water resources planning and management, and for harmonizing agricultural water use and eco-environmental water requirements. The Weihe River is the largest tributary of the Yellow River in China and an important water source for the Central Shaanxi Plain, which acts as the main driving force in the western economic development of China. However, this region also suffers great resource shortages. Ensuring sufficient freshwater resources supply is one of the most essential prerequisites for economic development and environmental protection in the Wei River Basin. Using the Soil and Water Assessment Tool (SWAT) model, this study investigated the spatiotemporal variations of blue and green water resources under different human activities (land use/cover change and irrigation) and climate variability scenarios during the 1980s-2000s for the Weihe River Basin. The results showed that: 1) Under the impact of land use/cover change, irrigation and climate variation, the blue water flow, green water flow and green water storage decreased by 23.56 mm/a, 39.41 mm/a and 17.98 mm/a, respectively, during 1980-2009. Blue water flow and green water storage presented an increasing trend in the north of study area, and the green water flow showed a decreasing trend in the upstream regions. 2) Attribution analysis showed that climate variability accounted for a decrease of 13.17 mm/a, 44.99 mm/a and 22.79 mm /a in blue water flow, green water flow, and green water storage, respectively. The blue water flow increased in the north of the Weihe River Basin, but decreased in the south of the Weihe River Basin. The green water flow decreased in the whole basin. Land use/cover change accounted for a decrease of 0.42 mm/a and 0.37 mm/a respectively in blue water and green water flow, but an increase of 0.79 mm/a in green water storage. In addition, irrigation accounted for a decrease of 9.97 mm/a in blue water flow and an increase of 5.95 mm/a and 4.02 mm/a in green water flow and green water storage, respectively. 3) Green water coefficient showed an increased trend in the southeast, but a deceased trend in the Jinghe River Basin due to the climate variability. Land use/land cover change drived the green water coefficient increased in some sub-basins of southwest. It should also be noted that the green water coefficient significantly increased in Central Shaanxi Plain when considered the irrigation factor.