怒江流域悬移质输沙时空分布特征及变化趋势

利用怒江-萨尔温江上游地区怒江流域5 个水文站长序列日悬移质输沙与径流观测记录,运用Mann-Kendall 检验和R/S 分析等方法,分析了50 多年来(1956-2011) 怒江干流和支流南汀河输沙时空格局和变化特征及其与径流的关系.结果表明：(1) 怒江干流平均含沙量和输沙模数远小于支流南汀河,流域悬移质输沙率年际变异系数随控制面积增大而减小;(2) 怒江干流木城站悬移质输沙率小于其上游道街坝站,部分泥沙淤积在区间河床可能是其原因之一;(3) 怒江流域悬移质输沙年内分配极不均匀,干流悬移质输沙集中程度在月以上时间尺度高于支流南汀河,而在日时间尺度则低于支流南汀河;(4) 怒江干流和支流南汀河悬移质输沙率均呈明显上升趋势,且未来仍将延续上升趋势,二者的突变分别始于1987 年和1980 年;(5) 怒江干流中上游悬移质输沙与径流的相关性不显著,中下游、下游以及支流南汀河悬移质输沙与径流的相关性均显著.

Temporal and spatial distribution and its change trend of suspended sediment transport in the Nujiang River Basin

Based on the long record of daily suspended sediment transport and runoff at the five hydrological gauge stations in the Nujiang River Basin, using the Mann-Kendall test and R/S (Rescaled Range Analysis) methods, this paper analyzed the spatial and temporal distributions, the change trend of sediment transport and its relationship with runoff in the basin from 1956 to 2011. The results showed that: (1) The average sediment concentration and sediment transport modulus of the Nanting tributary was much greater than those in the mainstream, and the inter-annual coefficient of variation of suspended sediment transport rate decreased with the increase of its catchment area; (2) In the Nujiang mainstream, the suspended sediment transport rate at Mucheng station is smaller than that at Daojieba station in the upstream, indicating that a part of sediment deposition in the river bed with the decline of river gradient may be one of the reasons for this phenomenon; (3) The annual distribution of suspended sediment transport in the Nujiang River was very uneven, and its concentration in the mainstream was higher than that in the Nanting tributary at the month scale but lower at the daily scale; (4) The suspended sediment transport rate showed a significantly increasing trend both in the mainstream and the Nanting tributary, and their mutagenesis started respectively in 1987 and 1980; (5) The relationship between suspended sediment transport and runoff was not significant in the upstream of Nujiang River, but significant in the middle and lower mainstream and Nanting tributary.