雅砻江流域REOF分区的降水特征及其未来趋势分析

研究区域降水对保障生态环境、发展有效灌溉面积、农业生产以及优化水库调度具有重要意义。以雅砻江流域为研究对象,利用该流域13个气象站1961—2018年的降水资料,使用旋转经验正交函数分解(REOF)划分为6个地理区并结合Daniel趋势分析、Mann-Kendall突变检验、滑动T检验和R/S重标极差法分析了雅砻江流域6个区1961—2018年的降水变化特征和未来降水趋势。结果表明:(1)每个区的降水量年代际变化特征明显,年际变化特征不明显,与流域整体降水特征一致; Ⅰ区的降水量整体在持续减少,Ⅱ—Ⅵ区的降水量整体呈上升趋势,流域整体降水呈上升趋势。(2)Ⅰ—Ⅵ区的降水量突变年份依次为1981年、2002年; 1981年; 2005年、2014年; 1978年、1997年、2001年、2011年; 1980年、2000年; 1980年、1998年、2001年。(3)6个分区在未来一段时间内,Ⅳ区的降水量与过去趋势相比将会下降; Ⅰ区、Ⅱ区、Ⅲ区、Ⅴ区及Ⅵ区的降水量与过去趋势相同并呈强持续性,其中Ⅲ区的降水量上升趋势时间长、持续性最强,与过去趋势变化最相符; 6个区的降水量受过去趋势影响的未来趋势时间长度依次为12 a,10 a,8 a,10 a,6 a,13 a。以上研究表明,雅砻江流域中下游的降水量上升幅度最大,而下游西南部(Ⅰ区)的降水量在显著持续减少,该现象会对水力发电、生态治理和农业生产带来一定的负面影响; 6个区降水量的显著年代际变化增加了局部旱涝发生的不确定性,降水量过去总体趋势对未来趋势的影响时间较长,这对于合理治理植被生态、做好水土保持工作、优化水库调度、发展有效灌溉面积和农业生产具有科学指导意义。

Analysis of Precipitation Characteristics and Future Trends in the REOF Subarea of the Yalong River Basin

The study of regional precipitation is of great significance for ensuring the ecological environment, developing effective irrigation area, agricultural production and optimizing reservoir operation. Taking the Yalong River Basin as the research object, we used the precipitation data of 13 weather stations in the basin from 1961 to 2018, used the rotating empirical orthogonal function decomposition(REOF)to divide into 6 geographic regions, and combined with Daniel trend analysis and Mann-Kendall mutation Test, sliding T test and R/S re-standard range method to analyze the precipitation change characteristics and future precipitation trends of 6 districts in the Yalong River Basin from 1961 to 2018. The results show that:(1)the inter-decadal variation of precipitation in each area was obvious, and the inter-annual variation was not obvious, which was consistent with the overall precipitation characteristics of the basin; the overall precipitation in area Ⅰ continued to decrease, and the overall precipitation in areas Ⅱ—Ⅵ was on the rise, and the overall precipitation in the basin was on the rise;(2)the abrupt years of precipitation in Ⅰ—Ⅵ areas were 1981, 2002; 1981; 2005, 2014; 1978, 1997, 2001, 2011; 1980, 2000; 1980, 1998, 2001;(3)in the six sub-regions, the precipitation in area Ⅳ will decrease compared with the past trend in the future; the precipitation in area I, Ⅱ, Ⅲ, V and Ⅵ will be the same and strong sustainability; the precipitation in District Ⅲ has the longest rising trend and the strongest sustainability, which is most consistent with the past trend; the during of the future trend of precipitation in the 6 districts affected by the past trend is 12 years, 10 years, 8 years, 10 years., 6 years, 13 years, respectively. The precipitation in the middle and lower reaches of the Yalong River has the largest increase, while the precipitation in the southwestern part of the lower reaches(Zone I)continues to decrease significantly, which has a negative impact on hydropower, ecological management and agricultural production. Significant interdecadal changes in precipitation in 6 districts increase the uncertainty of local droughts and floods. The past general trend of precipitation will have a longer impact on the future trend, which is of scientific guiding significance for the reasonable protection of vegetation ecology, soil and water conservation, optimization of reservoir scheduling and development of the effective irrigation area and agricultural production.