Abstract

Quantifying the relative contributions of climate change and human activities to water and sediment variations is of great importance for regional resources and river basin management, which has become a hot topic in hydrology research. In this study, water discharge and sediment load in Xiangxi River basin of Three Gorges Reservoir area were investigated based on hydrometeorological time series since 1960s. The non-parametric Mann-Kendall (M-K) test was used to detect both the trends and abrupt changes in the time series. Double mass curve and sediment rating curve method were used to quantify and evaluate the climatic and anthropogenic effects on water discharge and sediment load. Results indicated that both water discharge and sediment load showed significant decreasing trends with annual decrement rate of –0.08 × 10⁸ and ‒1.011 × 10⁴ t/yr, respectively. The abrupt change points were observed in 1991 for water discharge and 1999 for sediment load by sequential M-K test and cumulative anomaly curve analysis. This study demonstrated that water discharge was mainly influenced by precipitation in 1990s while by human activities ever since 2000, and sediment load was predominantly influenced by human activities (relative contribution 86–98%, regardless of whether the effect is negative or positive). In this study, soil and water conservation as well as land use change were primarily responsible for water and sediment variations in Xiangxi river basin especially since 2000. Further studies need to be done to quantify the importance of a specific driving factor at multi-timescales.

中文翻译：

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三峡库区湘西流域气候和人为因素对流量和泥沙量的定量影响。

摘要

量化气候变化和人类活动对水和沉积物变化的相对贡献对于区域资源和流域管理具有重要意义，这已成为水文学研究的热点。本文以三峡库区自1960年代以来的水文气象时间序列为研究对象，对湘西河流域的排沙量和排沙量进行了研究。使用非参数Mann-Kendall（MK）检验来检测时间序列中的趋势和突变。采用双重质量曲线和泥沙定额曲线法来量化和评估气候和人为因素对排水量和泥沙负荷的影响。结果表明，排水量和泥沙量均呈显着下降趋势，年递减率为–0.08×10 ⁸和‒1.011×10 ⁴ t / yr。通过顺序MK试验和累积异常曲线分析，分别在1991年的排水和1999年的泥沙负荷中观察到突变点。这项研究表明，自1990年代以来，水排放主要受降水影响，而自2000年以来，受人类活动影响最大，而泥沙负荷主要受人类活动影响（相对影响为86-98％，无论其影响是消极还是积极）。在这项研究中，尤其是自2000年以来，水土保持和土地利用的变化是湘西流域水沙变化的主要成因。需要进一步研究以量化特定驱动因素在多个时间尺度上的重要性。