Disturbed boundaries extraction in coal–grain overlap areas with high groundwater levels using UAV-based visible and multispectral imagery

Abstract

Coal-grain overlap areas (CGOA) with high groundwater levels are vulnerable to subsidence and water logging during a series of mining activities, which have adverse impacts on crop yields. Such damage requires full reports of disturbed boundaries for the agricultural reimbursement and ongoing reclamation. Since direct measurements are difficult in such a case because of vast, unreachable areas, so it is necessary to be able to identify out-of-production boundary (OB) and reduced-production boundary (RB) in the corresponding region. In this study, OB was extracted by setting thresholds through characteristics of the cultivated land elevation based on UAV-generated digital surface model (DSM) and digital orthophoto map (DOM).Meanwhile, aboveground biomass (AGB), the soil plant analysis development (SPAD) value of chlorophyll contents, and leaf area index (LAI), were used to select the appropriate vegetation indexes (VI) to perform a reduced-production map (RM) based on power regression (PR), exponential regression (ER), multiple linear regression (MR) and random forest (RF) algorithms. Finally, an improved OTSU segmentation algorithm was applied to extract mild RB and severe RB. The results show elevation threshold segmentation method and the improved OTSU segmentation method can accurately recognize and extract disturbed boundaries, which are consistent with the tonal difference after crop damage in the image. This study provides reference methods and theoretical supports for disturbed boundaries determination in CGOA with high groundwater levels for further agricultural compensation and reclamation processes.

Dynamic Monitoring of Winter Wheat Health in Mining Subsidence Areas by Combined Active and Passive Remote Sensing Technology

“…Based on the advantages of the red-edge vegetation index in monitoring crop growth and health, the use of the red-edge band for monitoring crop growth, damage, and health in coal-grain production overlapping areas have great potential for application. The research studies on the growth and health status of crops in mining areas mainly started with single indicators such as chlorophyll content [35], aboveground biomass [36], leaf area index [37], NDVI and EVI [38], and the ecological characteristics of crops reflected by a single indicator tend to be more one-sided. In fact, the health status of crops is closely related to the interaction of multiple indicators, especially in coal-grain production overlapping areas, where there is a diversity of damage caused by mining disturbances on crops.…”

Comprehensive Identification of Surface Subsidence Evaluation Grades of Mines in Southwest China

“…At present, for coal mines in the northern plains, mining surface subsidence is generally believed to be mainly related to the mining method, mining speed, mining depth, mining height, mining width and roof management [5][6][7][8][9][10][11][12]. At this stage, many scholars and experts have a relatively comprehensive understanding of the influencing factors of surface subsidence after coal mining in the northern plains [13][14][15][16].…”