The Influence Characteristics of Open-Pit Coal Mining on Groundwater Level in Baorixile

Abstract: In the context of extensive high-intensity mining in open-pit coal mines, the temporal and spatial changes of the groundwater level and the range of disturbance caused by the mining activities remain unclear, and the traditional hydrological observation methods are insufficient in obtaining accurate and real-time groundwater monitoring data under the open-pit mining conditions. To address these challenges, the construction of an automatic groundwater observation network to obtain long-term groundwater level dynamic monitoring data via wireless remote transmission, integrated with hydrological background value survey, open-pit coal mine production and drainage data, meteorological data, and hydrogeological data, will reveal the temporal and spatial change characteristics of groundwater under open-pit coal mining conditions and disturbances radius and area of influence on groundwater. The results show: 1) The drainage operation during the open-pit mining caused the drop of groundwater level and forming of a cone of depression, with maximum drawdown of the central groundwater level at 60 m. The disturbance mainly occurred in the mining area where the maximum groundwater disturbance radius was 8 km, and the disturbance area accounted for 66.7% of the mining area. and 10% of the hydrogeological units; 2) The range of groundwater level drop within the disturbance radius is closely related to the distance from the open-pit coal mine and the drainage volume. The closer the distance to the open-pit coal mine and the greater the drainage volume led to the greater the groundwater level drop; 3) The change characteristics of dynamic curve of groundwater can be divided into 3 types (weather-affected, unaffected and mining-affected). Therefore it is of great significance for groundwater resources protection and ecological restoration in open-pit coal mines to conduct automatic monitoring of groundwater, and study the influence of open-pit coal mining on groundwater by establishing a three-dimensional observation network of groundwater in open-pit mines.