Environmental issues in karst terrain: An example from Central India

Abstract

In this paper, an attempt has been made to highlight the nature of karst in central India and evaluate possible effects of environmental degradation of groundwater due to indiscriminate disposal of various types of wastes into karst terrains without subjecting them to any treatment before disposal. Karst features associated with carbonate rocks of the Proterozoic Vindhyan basin in central India and environmental issues related to the same area's groundwater resources are briefly given. Based on the process of formation, karst may be categorized as True karst (holo-karst) and (ii) Fluvial karst. On the other hand, based on the types of cover, karsts are classified into three types: (i) Covered karst, (ii) Soddy karst, and (iii) Buried karst. Three types of karst landforms identified in carbonate rocks of the Vindhyans are (i) Superficial landforms (Karren), produced mainly by solution action on the rock surfaces, (ii) Landforms due to fluvial erosion, and (iii) Underground landforms, i.e., Caves. In a particular hydrogeologic setting, the groundwater system consists of minor secondary porosity modified by solution activities. Accordingly, two types of groundwater flow systems (diffuse and conduit) occur in carbonate rocks. Due to karstification, limestones constitute the most productive aquifer in the area. It is noted that untreated municipal and industrial wastes are disposed of directly in surface water bodies and streams and associated sinkhole depressions in limestone terrain. Secondary openings being interconnected with each other gradually carry these pollutants to groundwater reservoirs in karst aquifers. The continued influx of pollutants to groundwater reservoirs through interconnected secondary voids would cause severe groundwater pollution in the long run and degrade the groundwater quality in karst aquifers for various usages.