北方半干旱快速城镇化流域径流变化的驱动因素分析

Driving factors on runoff change in the north semiarid rapidly urbanization watershed

通过社会经济发展对于流域水文过程产生的影响,分析城镇化流域的径流变化对于水资源管理保护和促进社会经济发展具有重要的作用。利用乌兰木伦河流域1997—2015年的水文气象、土地利用和社会经济等数据,以降水—径流双累积曲线、改进的Mann-Kendall检验和主成分分析等方法从不同时间尺度分析了流域径流、城镇化、气候和社会经济的变化趋势,揭示了气候、社会经济快速发展和城镇化过程对于流域径流的影响,发现了研究区年、季尺度下径流变化的主要驱动因素,并建立与不同时间尺度径流的映射函数关系。结果表明:在鄂尔多斯市快速城镇化影响下,研究区径流深呈现下降趋势,在2005年出现拐点变化;2005年之后的平均径流深小于之前的平均径流深;降水、蒸发、气温等气候因素没有显著变化趋势,但城镇化面积、GDP和人口明显增加,城镇化为2005年后研究区径流减少的主要驱动因素;城镇化对于枯水季径流的影响更为显著。

The hydrological process of a watershed influences a lot on the local socioeconomic development. The analysis of runoff change caused by the rapid urbanization on the watershed is of important significance in the man- agement and protection of the local water resource. In this study, based on the land use information from remotely sensed images ,the hydrometeorologieal observation data and the social economy data from 1997 to 2015, the rela- tionship between the influencing factors and the runoff trend in Wulanmulun River watershed was analyzed at differ- ent time scale using the improved Mann-Kendall Test and PCA （ principal component analysis） method. The results shows as follows ： （ 1 ） the runoff depth was dramatically decreased, and an inflection point occurred in 2005 which means the average runoff depth after 2005 was smaller than that before 2005 as the rapid urbanization started in 2006. （2） during the whole time period, there was not significant change for a few climate factors, such as the pre- cipitation, evaporation and air temperature. But the urbanization area, the population and GDP had been increased remarkably as a result of the quick urbanization which was the main reason resulting in the decrease of the runoff in the watershed after 2005. （3） the effects of urbanization on the runoff in dry season was more outstanding.