Assessment Of The Impact Of Sand And Gravel Mining On Land Use And Ecosystem Service Functions In Guizhou Province

Sand and gravel resources are one of the indispensable and important resources in urban and rural infrastructure construction,and it is the most consumed natural resource in the world after water resources.The annual global consumption of sand and gravel amounts to 50 billion tons,and China’s annual consumption of sand and gravel amounts to more than 20 billion tons,accounting for about half of the global consumption.Since the reform and opening up,China’s urbanization has accelerated and the natural sand and gravel from rivers is no longer sufficient to meet human needs,with the mechanism gradually replacing natural sand and gravel as the main source of sand and gravel.Guizhou Province is a major producer of sand and gravel and an important supplier of sand and gravel in China.In 2019,Guizhou Province proposed the strategy of"Guizhou’s stone out of the mountains",which intends to enhance Guizhou’s comparative advantage in the national sand and gravel market by vigorously developing sand and gravel mining activities in mountainous areas.Mechanized sand mining belongs to open-pit mining,and its extraction directly affects land cover and land use,leading to land degradation and a greater impact on human activities and ecosystem services.However,less attention has been paid to the impacts of the mining of machine-made sand,with most studies focusing on the impacts of river and marine sand mining,and lacking a systematic understanding of the impacts of the mining of machine-made sand;And Most of the analysis focuses on a single mine site,but less on the ecological impact of mining a particular mine type.Based on this,the thesis takes sand and gravel mines in Guizhou Province as the research object,and analyses the density of mine distribution and the mining intensity of mines in each county through nuclear density analysis and mining intensity calculation methods;Analysis of the impact of mining on land use,including the type and area of land occupied and the transfer of land during mining,using methods such as land transfer matrices and land movement attitudes;Estimating the amount of ecosystem service value lost due to mining using the equivalent factor method.The land suitability assessment method is used to evaluate the suitability of future mine land and to preferably select the best mine land rehabilitation plan.The main research theories are as follows:（1）in 2020,the total number of sand and gravel mines with mining rights is 1,791in Guizhou Province,covering a total area of 11,502.45 hm~2.Among the 9 prefectures（prefectures/cities）,the largest distribution of mines is in the Bijie area,with a total of422 mines;Guiyang City has the lowest distribution with only 49.The areas with the highest density of mines are located in the northern and western regions of Anshun City,while the areas with the lowest density of mines are located in the central and southern parts of Qiandongnan Miao and Dong Autonomous Prefecture.Among the 88 county-level administrative units in the province,13 county-level administrative units are counties with high mining intensity,accounting for 14.8%of the province.of the 9prefectures（prefectures/cities）,Guiyang City and Anshun City each have 3 counties with high mining intensity,which are the cities with the largest number of counties with high mining intensity.（2）Analyze the impact of mining on land use/cover change.The results show that The types of land occupied by mining are mainly Cropland and Forest land,and the area occupied varies from period to period.In 2010,Cropland and Forest land accounted for 45.72%and 38.48%of the total area of"mines mined earlier than 2015".In 2015,Cropland and Forest land accounted for 40.64%and 38.78%of the total area of"mines mined later than 2015".Between 2010 and 2020,in all 1,791 mines,land types with significant changes in size included Grass and Impervious Water Surfaces.Among them,grassland is mainly transferred from Cropland and Shrub land,and impervious water surface（mining area construction area）is mainly transferred from Cropland and Forest land.（3）Assess the impact of mine mining on ecological service functions,and the results show that the loss of ecosystem service value caused by mine mining in different periods is different,with a total loss of 634 million yuan.The loss of ecological service function value caused by mining varies in 9 prefectures（prefectures/cities）,among which Qiannan Buyi and Miao Autonomous Prefecture has the largest loss and Guiyang City has the least.From the perspective of the loss of ecosystem service value of various ecosystem service functions,the loss of climate regulation services is the largest,and the loss of water supply is the smallest.（4）Evaluating the suitability of future mine land,the results show that in the proposed selection of Forest land,Cropland and Construction land,only considering the restoration of a single land type,the most suitable land type for future mine restoration in Guizhou Province is Forest land,followed by Construction land,and finally Cropland.The most suitable land types in each area of the mining area are different,and the actual situation should be selected according to the characteristics of each mining area.Due to the different levels of economic development,the best mode of mine restoration in different places（states/cities）is different,the sand and gravel mine land in Tongren City is most suitable for restoration to Cropland,and the sand and gravel mines in the remaining 8 prefectures（prefectures/cities）are most suitable for restoration to forest land.In summary,the research results are expected to provide a theoretical basis for Guizhou Province to promote the implementation of the strategy of"Guizhou’s stone out of the mountains"and carry out mine land restoration.