黄河上游牧草区水热变化及土壤水分响应

Climate Evolvement of Water-heat and the Response of Soil Moisture in Grassland Area of the Upper Yellow River

利用月降水、气温等资料,分析甘南草原地区水热配置和土壤水分变化。结果表明:牧草生长期降水增多,成熟期降水减少;逐月降水、气温变化的线性趋势有明显差异;月降水明显减少和气温明显上升中存在突变,周期谱有明显差别。土壤水分存在显著下降趋势,在1995年发生了突变(转向明显负距平)。土壤水分年际演变与降水同向性较好,年代际变化与气温呈反位相配置;土壤水分演变振荡周期对降水短周期和气温长周期响应明显。

This paper mainly analyzes water-heat distribution and soil water variations in grassland area of southern Gansu by applying the EOF（empirical orthogonal function） and wavelet analysis. The results show there were jump-points in the evolvement of monthly rainfall and soil-water decreasing, and monthly temperature rise.The slopes of rainfall and temperature were different.The variation rate of monthly rainfall was -13.6mm/10a-4.3mm/10a and that of temperature, 0.883℃/ 10a-0.108℃/10a.The obvious correlations of rainfall and temperature with soil water during growth periods were observed.Also the variation evolvement of rainfall and temperature corresponded with weak 4-year variation period.The change of soil water had good relations with annual rainfall and inter-decadal temperature variations.The oscillation of soil water responded obviously on short rainfall periods and long temperature periods.