Sustainable Development of Ground Water in and around Opencast Limestone Mine Area by Rainwater Harvesting

Introduction

Groundwater is of paramount importance for an agriculture-based country like India. Being a leading asset, the use of groundwater, primarily for irrigation and for various development activities over the years has adversely affected the groundwater regime in many parts of the country. With 2.4 percent of the total land area and 4.0 percent of the total available water, India has to serve 17.5 percent of the world population and 30 percent of livestock. In the year 2010, annual water demand was 813 BCM and it is likely to be 1093 BCM by the year 2025 and 1447 BCM by the year 2050. Thus, the available utilizable water resource of the country is considered insufficient to meet all future needs.

The mining sector is gradually growing the quality of human life. But, while permitting mining, the disturbance to the hydrological regime should be minimal or as less as possible. This study determines the interrelation of the mining process with water in general and groundwater in particular. To understand the groundwater-related problems of the mine, the hydrological and geological setup of the area is first studied. Concerning any mine or the mining area, hydrogeological setup encompasses aquifer characteristics, that is, nature, type, parameters, etc.; all local and regional geological details; plans for mining and total picture of hydrology, drainage, discharge, etc. The approach for scientific investigation, to search for solutions, usually includes field monitoring (pre-monsoon and post-monsoon monitoring), instrumental survey, groundwater modeling, and mine planning, that is, drainage, dewatering, etc.

Surface mining and underground mining are two major methods of mining for the exploitation of minerals from the earth.  The role of groundwater is very important in both methods because mining has an influence on hydrology.

Understanding the Challenges: Opencast limestone mining involves the removal of topsoil and the excavation of the underlying limestone deposits. This process alters the natural hydrological cycle, leading to reduced infiltration and increased surface runoff. Consequently, the recharge of groundwater sources is significantly compromised, and nearby wells and boreholes may experience depletion or contamination.

Benefits of Rainwater Harvesting: Rainwater harvesting refers to the collection and storage of rainfall for future use. It offers several benefits when applied in opencast limestone mining areas:

Groundwater Recharge: By capturing rainwater, it can be directed towards recharge structures such as percolation pits, recharge wells, or infiltration trenches. These structures facilitate the replenishment of groundwater levels and restore the natural hydrological balance.

Reduced Surface Runoff: Harvesting rainwater helps minimize surface runoff and erosion in the mining area. This reduction in runoff prevents soil erosion and subsequent sedimentation in water bodies, preserving their quality and ecological integrity.

Diversified Water Sources: Rainwater harvesting provides an additional source of water, reducing the dependence on groundwater alone. This diversification of water sources helps maintain sustainable water supplies for both mining operations and local communities.

Improved Water Quality: Rainwater is relatively free from contaminants and pollutants present in surface water sources. By using harvested rainwater for non-potable purposes, such as dust suppression or industrial processes, the strain on groundwater quality is reduced.

Implementing Rainwater Harvesting: The successful implementation of rainwater harvesting in opencast limestone mining areas requires a comprehensive approach:

Site Assessment: Conduct a detailed assessment of the mining area's topography, rainfall patterns, and hydrogeological characteristics to identify suitable locations for rainwater harvesting structures.

Design and Construction: Engage hydrological experts to design and construct appropriate rainwater harvesting structures like check dams, percolation tanks, or recharge wells. These structures should be designed to maximize rainwater storage and infiltration into the groundwater aquifers.

Community Engagement: Involve local communities in rainwater harvesting initiatives. Raise awareness about the importance of sustainable groundwater management and encourage their participation in the construction and maintenance of rainwater harvesting structures.

Monitoring and Maintenance: Regularly monitor the performance of rainwater harvesting systems, including water quality and quantity. Ensure proper maintenance of structures to enhance their longevity and efficiency.

Conclusion: The sustainable development of groundwater in and around opencast limestone mining areas is crucial to protect the environment and meet the water needs of local communities. Rainwater harvesting techniques offer an effective solution to counteract the adverse impacts of mining on groundwater resources. By implementing these practices, we can restore groundwater recharge, reduce surface runoff, and promote the overall sustainability of water resources in these regions. Collaboration between mining companies, communities, and government bodies is vital to ensure the successful integration of rainwater harvesting into mining operations and create a sustainable future for all.