三江源区径流长期变化趋势对降水响应的空间差异

为探究三江源区径流长期变化特征的空间模式，采用Mann-Kendall趋势检验、双累积曲线法和GIS技术，分析1957—2012年三江源区降水和径流的变化趋势，以及径流对降水响应关系的空间差异.结果表明:1957—2012年三江源区有67.1%的区域年降水量呈显著增加趋势；47.3%的区域径流深变化趋势不显著，45.4%的区域显著增加；其余7.3%的区域内降水变化不显著但径流深显著减少.长江源区绝大部分区域降水量和径流量都显著增加，径流量增速达0.616 9×108 m3/a.澜沧江源区在降水显著增加或变化不显著的情况下，径流深无显著变化或显著减少.黄河源区内部差异很大，降水呈增加或无显著变化趋势，径流深则呈无显著变化或显著减少趋势.除澜沧江源子曲外，三江源区年径流深和降水量呈显著线性正相关，Pearson线性相关系数为0.51~0.87.径流量对降水量的响应关系存在明显的空间差异性，可以分为稳定型、波动型、上升型及下降型4种类型，并以稳定型为主，涉及面积占三江源区总面积的48.9%；其次为下降型和波动型，分别占32.8%和12.9%；上升型涉及面积所占比例最小，仅为5.5%.研究显示，三江源区61.8%的区域内径流对降水的长期响应关系并未发生明显变化，或者在波动中保持相对稳定的关系. 

Spatial Variation of Long-Term Runoff Trends and Response to Precipitation Change in the Three-River Headwaters Region

To understand the spatial patterns of long-term runoff variation in the Threek-River Headwaters Region, the spatial variation of the trends of precipitation, runoff and the response of runoff to precipitation changes were investigated using Mann-Kendall trend test, double accumulation curve and GIS, based on hydro-meteorological data from 45 meteorological stations and 17 hydrological stations within or around the region. The results showed that:(1) The areal average precipitation in this region increased first and then decreased from 1957 to 2012. A significantly increasing trend was found at 15 of 45 meteorological stations, which accounts for 67.1% of the region. (2) In most areas, runoff changed corresponding to the trend of precipitation, with 45.4% increasing significantly, and 7.3% decreasing significantly. Both precipitation and runoff increased significantly in most parts of the Yangzi River Source region. Total runoff of the Yangzi River increased at the rate of 0.616 9×108 m3/a due to the significant increase in precipitation. However, in the Yellow River Source region, the response runoff to precipitation change was more complicated because of the effects of soil and water conservation practices and LUCC (landuse/cover change). (3) Significantly positive relationships were found between the annual runoff and precipitation, with the Pearson's correlation coefficients ranging from 0.51 to 0.87 in 16 of the 17 contributing areas gauged by the 17 hydrological stations, with the exception of one branch of the Lancang River. The responses of runoff to precipitation were classified into four patterns, i.e., stable (accounting for 48.9% of the total area), descending (32.8%), fluctuant (12.9%) and ascending (5.5%). In 61.8% of areas of this region, the responses of runoff to precipitation were stable or fluctuant. The ascending and descending responses of runoff to precipitation reflected the influence of glacier change and human activities in the remaining 38.2% of areas.