Making method of tracking monitoring scheme for abandoned industrial and mining land reclamation and its empirical research

Abstract: Abandoned land is a special kind of land space which is damaged by industrial and mining activities. Due to being abandoned for a long time, complicated formation and uncertain factors, the improvement of soil fertility and quality during abandoned land reclamation requires a long process. So tracking monitoring and evaluation work is really important. A making method of tracking monitoring scheme for abandoned land reclamation includes the layout of monitoring points, the establishment of the minimum data set of monitoring indicators, as one of the means of monitoring soil, surface water, groundwater and crop. A case study on a reclamation project of an abandoned sulfur mine land was carried out in the southwest area of China. With the help of 3S (remote sensing, RS; geographical information system, GIS; global positioning system, GPS) and geostatistics, we proposed monitoring point layout scheme, and monitoring indicators, and established the minimum data set as one of the means for soil, groundwater, surface water and plant. Considering the reclamation measures and monitoring index of spatial heterogeneity and the reclaimed land quality evaluation results, multi-layer spatial overlap was adopted to form monitoring units and monitoring points; considering the existing land reclamation quality factors and variability, through the analysis of the existing index average value, the single pollution index, exceeding rate, rhichness and rangeabilty to obtain the minimum data set of monitoring indicators. The monitoring sites of reclaimed soil, crop, ground water, and surface water were 53, 5, 5 and 1, and 2 kinds of monitoring types were collected. A minimum data set of 15 indicators was constructed, covering the quality of construction, environment, soil fertility, and so on. The reliability of the monitoring points was validated and evaluated from the monitoring point number and spatial layout using the coefficient of variation, relative deviation, variable range of variation function and Moran's Index according to the monitoring scheme proposed in the paper. The evaluation results showed that the number of monitoring points obtained according to monitoring scheme was close to the number in verification calculation, which met the requirements. Compared with the 138 samples in 2015, the number of monitoring points decreased by 61.59%, the monitoring index was reduced by more than 50%, the distribution of monitoring points was more uniform, the monitoring content was more comprehensive, and the monitoring cost was saved; the actual sampling distance (average 456 m) did not exceed the monitoring index range of variation function, and there was no need to refine the monitoring unit or monitoring point; the spatial distribution characteristics of monitoring points were random or between clustered and random, which was not significant (P>0.05), and the monitoring points layout was ideal. This shows that the making method of tracking monitoring scheme is scientific and feasible. The tracking monitoring scheme can guide the quality improvement project for the reclamation of abandoned mine land and also provide a technical support and empirical basis for developing the tracking monitoring standards of abandoned land reclamation.