黄河(内蒙古段)水沙运动过程特征及演变趋势

Runoff and Sediment Transport Process Characteristics and Evolution Trend of the Yellow River Inner Mongolia Reach

近年来受上游水库、河道控导工程和气候变化等因素影响,黄河(内蒙古段)呈现水沙异源、水少沙多的特性,导致河道萎缩和泥沙淤积严重,河道形态演变剧烈,严重威胁夏汛及凌汛行洪安全,也对河道及两岸的生态环境造成严重影响。选取黄河(内蒙古段)干流入境石嘴山水文站和出境头道拐水文站水沙过程为研究对象,分别采用频谱分析法、R/S极差分析法和Markov链分析法系统研究2009-2016年两站逐月水沙运动变化的时序、运动状态和演变特征,讨论影响水沙运动变化过程的关键因素。结果表明:石嘴山站和头道拐站输沙量的变化周期均为1年,而径流的变化周期分别为1年和6个月;石嘴山和头道拐站径流Hurst指数值分别为0.576和0.515,输沙量Hurst指数分别为0.519和0.249;黄河(内蒙古段)丰水低沙和枯水高沙概率之和约为50%;水沙运动演化过程中,丰水高沙与枯水低沙极限概率之和大于0.8。受期间特殊的来水来沙过程、水文气候特征及人类活动的影响,黄河(内蒙古段)水沙运动时序特征呈现非同步性和不协调性,未来水沙运动过程趋势逐渐向协调演变。

Due to the impact of upstream reservoir, control project and climate change, the Yellow River Inner Mongolia reach has the characteristics of different sources of runoff and sediment, less water and more sediment. This phenomenon leads to sediment deposits, sharply decline and morphological evolution violently. This is seriously threatening the safety and ecological environment during summer flood and ice flood period. Shizuishan and Toudaoguai hydrologic station runoff and sediment transport process were chosen to analysis water-sediment time-order character, motion state and evolution characteristics by using spectral analysis method, R/S range analysis method and Markov method from 2009 to 2016. The results showed that the sediment transport variation period was one year at Shizuishan and Toudaoguai hydrologic station, but runoff variation period was one year and six months for the two stations respectively. Runoff Hurst number was 0.576 and 0.515, and sediment transport Hurst number was 0.519 and 0.249 respectively at Shizuishan and Toudaoguai hydrologic station. The probability of abundant flow low sediment and less discharge high sand was about 50%, the sum of the limit probability of large discharge high sediment and water shortage low sediment transport was greater than 0.8. There were asynchronization and incongruity of runoff and sediment time-order characters by the effect of incoming runoff and sediment process, hydroclimatic characteristics, human activities. Runoff and sediment transport process will be gradually coordinated in the future.