黄土高塬沟壑区绿水对土地利用和气候变化的响应研究——以南小河沟流域为例

Impacts of land use change and climate variation on green water in the Loess Plateau Gully Region——A case study of Nanxiaohegou basin

黄土高原地区生态环境脆弱,水资源十分匮乏,生产、生活和生态用水受到严重威胁。本文选择黄土高塬沟壑区典型小流域——南小河沟流域为研究对象,分别采用水量平衡法和Zhang模型法评价了该流域1954—2012年的绿水资源量,利用Mann-Kendall统计检验法对年绿水量进行了趋势分析和突变点检验,并探讨了绿水对土地利用和气候变化的响应规律,定量评价了两者变化对绿水的影响。结果表明:与水量平衡法相比,Zhang模型法的拟合结果较好,流域多年绿水资源量为443.2 mm,年绿水量呈不显著的下降趋势,突变时间发生在1978年;各土地利用类型绿水的年际变化不均,其中林地绿水量最大,草地次之,建筑用地最小;气候变化对绿水的影响中,降水是影响绿水的主要限制因素;根据情景分析法的计算结果,1954—2012年期间气候因素和土地利用因素对绿水变化的贡献率分别为123.6%和-23.6%,分离评判法的计算结果为137.7%和-37.7%,因此气候变化对绿水的影响要远大于土地利用变化,而林地面积增加是土地利用变化使绿水量增加的原因。该研究可为黄土高原区域生态环境恢复、区域水资源规划管理提供合理有效的理论依据。

The ecological environment of Loess Plateau gully area is fragile,and the water resources arevery scarce. In this study,the typical small watershed gully area of the Loess Plateau—Nanxiaohegou basinwas selected as the study area. The variation of green water in Nanxiaohegou was revealed based on landuse and meteorological data,furthermore,response of green water to climate and land use change was ana-lyzed. Besides,this paper made some researches quantifying the respective contribution of land use and cli-mate changes to green water from 1954 to 2012. The results show that：（1） The mean annual green waterof Nanxiaohegou basin is 443.2mm. According to the K-M statistical test,green water of Nanxiaohegou ba-sin shows a decreasing trend, but the trend is not obvious. At the same time, according to the UF andUB curves of the position of the intersection, annual green water mutated around 1978.（2） Interannualvariation of green water in different land use types is uneven, among which the green water in forest isthe largest,grassland comes second and construction land is the least;the precipitation is a major limitingfactor affecting green water in climate variation.（3） According to the results of scenario analysis,the con-tribution rate of climate and land use change to the annual green water reduction are 123.6%and-23.6%, while the results calculated by the separation of evaluation method are 137.7% and-37.7%.It indicates that the contribution of climate factors for green water change is more than that of the landuse factors, while the increase of forest area is the reason for green water increase because of the landuse change. The research provides a reasonable and effective theoretical basis for the restoration of regionalecological environment,regional water resources planning and management of the Loess Plateau.