Optimal Sampling Design For Reclaimed Soil Monitoring In Mining Area Based On Simulated Annealing

Soil properties of reclaimed land in mining area altered inevitably due to human activities.To realize sustainable land management and use in mining area,the longterm dynamic monitoring of soil properties is needed.The quality of soil monitoring information depends on the trustworthiness of the sample.Traditional dense sampling network is time consuming and expensive.Therefore,it is necessary to devise a scientific sampling scheme that maximizes the accuracy of results while minimizes the expends.In this study,dumps in Antaibao and Anjialing opencast coal mine were selected as the study area.Topographical factors were extracted from DEM and SPOT data and soil properties of soil samples collected in August 2017 were measured in laboratory.The spatial variability of soil organic carbon,bulk density,clay,silt and sand and their correlation with ancillary factors were studied.In addition,a separate optimal sampling design was made for each soil property and an optimized sampling scheme integrating various soil attributes was conducted based on simulated annealing method.The results are as follows:(1)The soil organic carbon showed a high variability and its content in southern dump was relatively high due to the long reclamation time;(2)Compared with the general simulated annealing algorithm,the number of sampling points reduced,the spatial correlation increased and the sampling points obtained by the improved simulated annealing showed more accurate predictions;(3)Compared with the statistical method,the improved simulated annealing considered the spatial correlation and the number of sampling points was greatly reduced;(4)The sampling points were mostly distributed in the marginal areas and appropriately added in the middle of the dump.There were more sampling points distribution in areas with large changes in terrain for each soil property after improved simulated annealing optimization and more sampling points were needed to reflect soil information in southern dump in Antaibao opencast coal mine.The optimal structure of sampling pattern integrating all the attributes was similar to that of the organic carbon.When performing multi-attribute sampling optimization,the sampling points for various soil properties were considered and the optimal structure of sampling pattern showed a uniform distribution.This study provides a theoretical basis for optimal sampling design of soil properties monitoring and digital mapping prediction,serving the sustainable land management and use.