Articles written in Journal of Earth System Science

• Spatial estimation of groundwater storage from a 2D specific yield in the crystalline aquifer of the Maheshwaram watershed

Crystalline aquifers are present in most parts of southern India with limited resources of groundwater. The groundwater storage map in the Maheshwaram watershed has been estimated from the product of specific yield (Sy) and saturate aquifer thickness as a system being an unconfined weathered–fractured combined aquifer. Land-use data has been used for the estimation of groundwater abstraction at a spatial scale. Storage and scarcity mapping demonstrate that the watershed is clearly vulnerable to drought in some areas because of significant pumping. Therefore, the result shows that on average, the availability of groundwater storage corresponds to 1.5 yr of the present groundwater abstraction rate with successive low monsoons (i.e., insignificant recharge). Additionally, 13% of the area shows no storage at present, 28% of the area has less than 1 yr, 40% area has less than 2 yr and 12% area has less than 3% of storage. Very few cells can sustain for more than 3 yr. Additionally, the Sy of the aquifer ranges from 0.2% to 5% with a mean value of 1.8%. A geo-statistical technique has been applied for the estimation of Sy at unknown cells where either the cell was dry or no pumping occurred. This estimated two-dimensional Sy value can also be used in classical groundwater numerical modelling for a better understanding of groundwater resource management.

• Hydrogeological simulation for groundwater management strategies in crystalline aquifers, southern India

Crystalline hard-rock aquifers, one of the most complex groundwater systems, are facing serious groundwater management issues due to their limited storage capacity and understanding of their complex hydrogeological characteristics. In this study, we have employed an operational decision support tool to calculate the groundwater budget under variable agro-climatic conditions for groundwater management in the crystalline hard rock aquifers of the Ankasandra watershed (${\sim}$380 km$^2$), southern India. The nature of fractures and the aquifer geometry are categorized based on a borehole camera logging and resistivity model derived from the airborne electromagnetic (AEM) survey. The water level and groundwater recharge, simulated at the seasonal time step for the three hydrological years from June 2015–May 2018, show a negative trend for all years with groundwater depletion of ${\sim}$19 m, indicating the status of the aquifer is overexploited. The futuristic simulations further predict that the depletion in water level would result in an increasing number of drying up of borewells and perhaps zero water days in coming years if no appropriate measure is taken. The model also suggests that changes in land use with a significant increase in artificial recharge in the coming years could rapidly transform the groundwater scenario and lead to a long-term sustainable management solution.

• Journal of Earth System Science

Volume 131, 2022
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Posted on July 25, 2019