摘要:稳定氢氧同位素可有效示踪区域降水水汽来源，旱季降水补给对大规模哈尼梯田的持续存在具有重大影响。以哈尼梯田世界遗产核心区的全福庄河流域为研究对象，在2015年11月-2016年4月间的旱季期间逐月采集处于不同海拔的7个样点的降水样品42个，分析其稳定氢氧同位素组成的变化及其影响因子，并利用后向轨迹模型（HYSPLIT）追踪其水汽来源。结果表明：1）该区局地大气降水线方程为δD=7.31δ¹⁸O+19.8（R²=0.94，P<0.01，n=42），斜率较全球降水线小而截距偏大，说明研究区有多个水汽来源地。2）旱季降水δ¹⁸O和d-excess在前期快速富集，后期δ¹⁸O富集的速度减缓，d-excess则快速降低，体现出水汽来源具有时间差异，但两者在空间变化上不明显。3）旱季降水δ¹⁸O与降水量、温度和相对湿度的多元线性回归方程为：δ¹⁸O=-0.002P-0.86T-0.39H+38.22（R²=0.96，P=0.05），表明其变化是多因素综合影响的结果。4）结合δ¹⁸O、d-excess和HYSPLIT模型分析，该区旱季主要有3条水汽来源路径，其中西风南支和局地水汽补给较少，占优势的西南季风除2月份外其余各月占70%左右。5）研究区旱季降水量总体较少，但西南季风在11月带来的降水为"灌水养田"提供了水源，在4月的降水为"冲水肥田"和"栽插准备"活动提供了必要水源，从而保障了梯田旱季的用水需求。



Abstract:Stable hydrogen and oxygen isotopes can effectively trace the moisture sources of precipitation. Precipitation recharge has a significant impact on the stability of Hani Rice Terraces during the dry season. This paper selected the Quanfuzhuang River Basin in the core area of Hani Rice Terraces World Heritage as the study area during the dry season from November 2015 to April 2016. We analyzed the variation of precipitation isotope and its impact factors, and used HYSPLIT model to track moisture sources. The results indicated that:1) the Local Meteoric Water Line equation was δD=7.31δ¹⁸O+19.8 (R²=0.94, P<0.01, n=42), with smaller slope than the Global Meteoric Water Line and larger intercept. 2) The δ¹⁸O and d-excess rate rapidly increased in the early dry season, but δ¹⁸O rate was slow down in the late period, and the d-excess rate rapidly decreased, which showed that the moisture sources had time differences. However, the spatial variation was not obvious. 3) The multiple linear regression equation of δ¹⁸O and temperature, precipitation amount, and relative humidity during the dry season is δ¹⁸O=0.002P-0.86T-0.39H+38.22 (R²=0.96, P=0.05), indicating that the precipitation isotopic changes was the result of multiple factors during the dry season. 4)The backward trajectory model showed that there were main three moisture source routes during the dry season. The moisture vapor from South Branch of westerly and local transport were less, and the dominant southwestern monsoon accounted for about 70% in every month except February. 5) The precipitation amount was generally small during the dry season, but the precipitation at the end of the southwest monsoon provided water sources for irrigation in November. The precipitation from southwest monsoon next year was beneficial to fertilization and planting in April. The process provided necessary water source to guarantee the water demand of terraces during the dry season.





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