Spatial-temporal dynamic monitoring of sand dredging activities based on GF-1 WFV in Lake Poyang during 2013-2020

Abstract

鄱阳湖是目前我国最大的淡水湖，采砂活动对湖泊水质影响明显，但对采砂活动进行全面的现场监管较为困难.不过，采砂船工作时会明显改变附近水体悬浮泥沙的浓度，这一易于被遥感技术检测到的信息为解决这一问题提供了思路.本研究使用2013—2020年共133景GF-1 WFV影像对鄱阳湖采砂活动进行监测，并总结鄱阳湖采砂活动变化的时、空间规律.结果表明，1）2013年以来，鄱阳湖的年平均采砂船检测数呈先增多后减少的趋势，2016年是采砂活动的顶峰，年平均检测数为9.85艘，2019年后采砂船的年平均检测数锐减至3艘左右，其中监管政策是最主要的影响因素；2）鄱阳湖采砂活动向南湖扩展的趋势在2016年得到了有效的遏制，并在2018年后一直维持在很低的水平；3）在2019年全面禁止采砂后，仍然在松门山岛、星子县及笔架山附近监测到了零星的采砂船作业点.本研究不仅可以评估近年来鄱阳湖采砂活动监管的成效，也能给相似水域采砂活动的监管及其效果评估提供参考.;Lake Poyang is the largest freshwater lake in China, whose water quality is easily affected by sand dredging activities, and it is difficult to conduct comprehensive on-site supervision on the lake. However, the concentration of suspended sediment in nearby water will be changed when the sand dredgers are working, the above information which can be detected by remote sensing technology provides ideas for solving this problem. In this study, we use 133 GF-1 WFV data from 2013 to 2020 to monitor the sand dredging activities in Lake Poyang and then summarize the spatial-temporal patterns of sand dredging activities in Lake Poyang. The results are as follows:1) Since 2013, the annual average number of sand dredgers detected in Lake Poyang has shown the trend of increasing first and then decreasing, which peaked at 9.85 per scene in 2016. After 2019, it sharply decreased to about 3, and the supervisory policy is the most important factor in this case; 2) The expansion trend of sand dredging from Lake Poyang to South Lake has been effectively curbed after 2016, and has remained at a very low level since 2018; 3) Sporadic sand dredging operations can still be detected near Songmenshan Island, Xinzi County and Bijia Mountain even after the total ban on sand dredging in 2019. Our study not only evaluates the supervision effect of sand dredging activities in Lake Poyang in recent years but also provides a guideline for the supervision and effect evaluation of sand dredging activities in similar basins.