为了研究雅砻江流域的干湿状况,旨在为该地区气候区划和农业生产布局提供科学依据。利用1961—2017年雅砻江流域及周边16个气象站的逐月气象资料,使用FAO Penman-Monteith公式计算了研究区域的潜在蒸散量,进而求得干湿指数,并通过气候倾向率、Mann-Kendall(M-K)趋势检验以及突变检验等方法,分析了雅砻江流域干湿状况时空变化特征及空间差异。结果 表明:近57年来,雅砻江流域干湿指数略有上升趋势,变化倾向率为0.002/10 a; 年内干湿指数总体上呈单峰变化,峰值出现在6—9月; 空间上,干湿指数自下游向上游先减小后增加,高值中心位于下游的康定和越西站,低值中心位于中游的甘孜和新龙站; 根据M-K趋势分析,雅砻江流域下游除西昌站外干湿指数呈显著下降趋势,中上游除清水河、石渠外呈显著上升趋势,整个流域约69.41%的地区呈显著上升趋势; 根据M-K突变分析,雅砻江流域干湿指数分别在1977年、2005年发生了从干到湿、从湿到干的突变; 干湿指数与平均气温、相对湿度、平均风速和降水量呈正相关,与日照时数和潜在蒸散量呈负相关,与相对湿度的相关系数最大。
In order to study the dry and wet conditions of the Yalong River Basin, to provide a scientific basis for the climate division and agricultural production layout in the region, based on the monthly data of 16 meteorological stations in the Yalong River Basin and its surrounding areas during the period 1961—2017, the potential evapotranspiration and dry-wet index of the study area were calculated using the FAO Penman-Monteith formula. The methods including climate tendency rate, Mann-Kendall(M-K)trend test and mutation test were used to analyze the spatial and temporal variations and spatial differences in dry and wet conditions in the Yalong River Basin. The results show that the dry-wet index of the Yalong RiverBasin slightly increased in the past 57 years with a change tendency rate of 0.002/decade; the dry-wet index showed a unimodal seasonality peaking from June to September; spatially, the dry-wet index decreased and then increased from the downstream to the upstream, the highest value was observed at Kangding and Yuexi stations in the downstream section, while the lowest was found at Ganzi and Xinlong stations in the midstream section; the M-K trend analysis suggests that the dry-wet index in the downstream of Yalong River Basin significantly decreased except Xichang station; the the dry-wet indoces of the middle and upper reaches showed a significant increaseing trend except Qingshuihe and Shiqu stations; overall, the dry-wet indices showed the significantly increasing trend over around 69.41% of the basin; according to the M-K mutation analysis, the dry-wet indices in Yalong River Basin abruptly changed from dry to wet conditions in 1977, and from wet to dry conditions in 2005; the dry-wet indices are positively correlated with average temperature, relative humidity, average wind speed and precipitation, and are negatively correlated with sunshine hours and potential evapotranspiration, the correlation coefficient between dry-wet index and relative humidity is the greatest.
