Springs in a headwater basin in the Deccan Trap country of the Western Ghats, India

Available literature reveals that little work has been done on the origin of springs in a basaltic terrain. Close examination of such springs in about 2,000km super(2) of the upper Koyna River basin in the Deccan Trap country of the Western Ghats (hills), India, reveals that their origins are dependent on the lithologic character of different basaltic flow units and the existing physiography. Although rainfall, its seasonality and areas of recharge, play vital roles in the recharge of these springs, their yields are also controlled by lithological variations and hydraulic characteristics of their source-aquifers. Chemical concentrations of these springs are heavily dependent on the lithological compositions of the source-aquifers and the residence time of groundwater in these aquifers. Currently, basaltic springs are classified with those issuing from other terrains. However, because the emergence of groundwater in the form of springs is largely controlled by the lithology and the resulting water-bearing properties of the formations, a new classification scheme is proposed that classifies the springs on the basis of their source-aquifers. While tapping springs for drinking/irrigation purposes, it must be remembered that they also sustain thousands of other life forms vital to a balanced ecosystem. Changes in the uses of these springs may also affect other human communities downstream. Therefore, before developing spring flow, a trade-off must be made considering local needs and downstream users. Emphasizing only local human needs may lead to severe intercommunity conflict and negative environmental consequences.Original Abstract: Une recherche bibliographique montre qu'il existe peu de travaux sur l'origine des sources en terrain basaltique. Un examen detaille de telles sources sur environ 2,000km super(2) dans le bassin de la riviere Koyna, dans la region des traps du Dekkan des Ghats (collines) de l'ouest (Inde), montre que leur origine depend de la lithologie des differentes unites de coulees basaltiques et de la physiographie actuelle. Bien que la pluie, sa saisonnalite et les zones de recharge jouent un role essentiel dans l'alimentation de ces sources, leur debit est aussi controle par les variations lithologiques et les caracteristiques hydrauliques des aquiferes qu'elles drainent. La composition chimique de leurs eaux depend tres fortement de la composition lithologique des formations aquiferes drainees et du temps de sejour de l'eau souterraine. H