Environmental impact of quarrying of building stones and laterite blocks: a comparative study of two river basins in Southern Western Ghats, India

Mining and quarrying for minor minerals impart significant economic, environmental and social impacts in and around the affected areas. The problem is severe in the small river catchments as the effective area available for assimilating negative impacts of the activity is minimal, compared to large river basins. To address these issues, an investigation has been carried out in two river basins of southern Western Ghats (India)—the Netravati–Gurpur and Periyar–Chalakudy river basins. Both these basins host two important port cities of south India—Kochi and Mangalore. The study reveals that about 6.75 × 10⁶ ty⁻¹ of hard rocks are being extracted in the Netravati–Gurpur basin through 64 quarries. At the same time, the total number of quarries and extracted amounts in the Periyar–Chalakudy river basin are 525 and 10.47 × 10⁶ ty⁻¹, respectively. Many hillocks in the region are turned to a cluster of ugly scars, degrading the ecology and aesthetics of the area. Lowering of water table, modification or disappearance of natural drainages and environmental pollution are some of the other observations noticed in the area. The environmental impacts of laterite quarrying are comparatively less than that of rock quarrying as removal of the hard laterite cap rock enhances water percolation and makes the area more irrigable for agriculture. The study stresses the need for environment-friendly quarrying alternatives with stringent guidelines to improve the overall environmental quality of the area on one hand and to meet the developmental requirements on the other.