长江上游采砂分布及破坏滩群恢复能力模拟研究

Distribution of sand excavation area and simulation of recovery ability for destroyed gravel shoals in upstream of the Yangtze River

随着长江上游地方经济快速增长,建筑行业日益兴旺,砂石需求量与日俱增,沿江江砂开采规模不断扩大,滥采乱挖给河道防洪和航道安全带来不利影响。以宜宾-重庆涪陵河段为例,基于2007-2016年的河道地形资料研究沿线采砂分布状况,并采用平面二维水沙数学模型对破坏的滩面恢复过程进行模拟。分析结果表明,宜宾-涪陵河道采砂累计量约为3.95亿m^3,部分卵石滩滩面破坏,引起局部高差变化达40 m,其对地貌的改变远远超过河道自身调整与航道整治工程的影响;考虑上游水库群的联合调度及河床卵石存量的限制,已破坏的滩面采砂区基本无法恢复至原有形态。

With the development of the economy along the upstream of the Yangtze River,the construction industry is prosperous,and the demand for the sand increases rapidly,leading to an expansion of the sand excavation in the Yangtze River.The risk of the flood control and navigation safety is raised by the major sand mining.This study aims to investigate the scale of sand excavation and its influence on the gravel shoals.Based on the data set of the river bed level from Yibin to Fuling reach between 2007 and 2016,we obtain the distribution of the sand mining,and simulate the recovery process for the destroyed shoal by the 2D hydro-sediment numerical model.The results show that the amount of the sand mining is about 0.395 billion m^3,the gravel shoals are destroyed,and the difference in elevation can reach to 40 m,which indicate that the influence of the sand excavation on the topographic change is beyond that of the channel self-organization and the channel regulation;the destroyed shoal cannot return to the original form,due to the reservoirs mulit-operation in the upstream and the limitation of the sediment storage in the channel.