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章水流域输沙变化对水文气象因素的响应

Response of sediment variation to hydrological and meteorological factors in Zhangshui watershed

  • 摘要: 输沙是流域关键水文要素之一,深入探究其变化特征及影响因素,对流域水土流失综合治理具有重要意义。以赣江上游章水流域为研究区,基于1961—2018年的实测水文气象数据,采用Mann-Kendall检验、小波分析等方法分析输沙变化特征,通过逐步回归分析法筛选出输沙变化的显著性影响因素,利用通径分析量化各因素对输沙的直接、间接和综合影响。结果表明:1)输沙量年内分配不均匀,呈单峰型分布,主要集中在4—6月;年际上,输沙量呈极显著下降趋势(P < 0.01);周期变化上,主要存在3~7、11~19和21~30 a这3种时间尺度的变化周期,第1主周期为16 a;2)输沙量减少的显著性影响因素为径流量、风速和气温,三者的贡献率分别为52.5%、28.8%和-18.7%;3)径流量、风速和气温对输沙减少的直接影响排序为径流量>风速>气温,间接影响排序为风速>径流量>气温,综合影响排序为径流量>气温>风速。研究成果可为流域水沙调控、水土流失综合治理奠定理论基础。

     

    Abstract:
    Background Sediment is one of the key hydrological factors in the watershed. In-depth exploration of its variation characteristics and influencing factors is of great significance to the comprehensive management of soil erosion in the watershed. Zhangshui watershed is the main sediment-producing area of Ganjiang river, and it is one of the regions with the longest time series of observation data in Yangtze River basin. In this paper, the Zhangshui watershed in the upper reaches of the Ganjiang river was taken as the study area to analyze the variation characteristics of sediment transport and the direct, indirect and comprehensive effects of hydrological and meteorological factors on sediment transport.
    Methods Based on the measured hydrological and meteorological data from 1961 to 2018, the Mann-Kendall test method was used to analyze the trend change characteristics of sediment discharge, and the wavelet analysis method was used to analyze the periodic change law of sediment discharge. The significant influencing factors of sediment changes were screened by stepwise regression analysis. The direct and indirect path coefficients and decision coefficients of each factor on sediment discharge were calculated by path analysis, and then the direct, indirect and comprehensive effects were analyzed.
    Results 1) The annual distribution of sediment was uneven, showing a single peak distribution, mainly concentrated in April to June; the annual sediment showed an extremely significant decreasing trend (P < 0.01). In terms of periodic variation, there were mainly three-fold scales of 3-7, 11-19 and 21-30 years, and the first to fourth main periods of sediment variation were 16, 6, 4 and 25 years. 2) The significant indigenous influencing factors of sediment reduction were runoff, wind speed and temperature, and their contribution rates were 52.5%, 28.8% and -18.7%, respectively. 3) The direct path coefficients of runoff, wind speed and temperature to the reduction of sediment transport were 0.73, 0.40 and -0.26; the direct impacts of runoff, wind speed and temperature on sediment reduction were ranked as follows: runoff > wind speed > temperature. The indirect path coefficients were: -0.03, 0.61 and -0.02; the indirect impacts were ranked as follows: wind speed > runoff > temperature. The decision coefficient was: 0.50, 0.14 and 0.17; the comprehensive impacts were ranked as follows: runoff > temperature > wind speed.
    Conclusions Runoff, wind speed and temperature have an important influence on the change of sediment in Zhangshui watershed. The decrease of runoff, the decrease of air temperature and the increase of air temperature are the main reasons for the decrease of sediment in Zhangshui watershed. The research results can lay a theoretical foundation for watershed water and sediment regulation and comprehensive control of soil and water loss.

     

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