Groundwater Development In Semi-Arid South India: Trends and Status
Groundwater Development In Semi-Arid South India: Trends and Status
Previously Published Material: The manuscript is currently under final stage of preparation and it would be submitted for publication in February.
Abstract ID#: 34085
English Abstract:
Growing number of studies have indicated declining groundwater levels in the semi-arid southern region of India, however the statistical significance of the change in the level has not been analyzed. This study attempts to determine whether the semi-arid southern India is experiencing significant decline by analyzing the long term (1990-2012) groundwater levels data for three districts (administrative division in a state) with diverse land uses. Based on the length of the record, data from monitoring wells were divided into three time periods: 1990-2012 (group A), 1990-2005 (group B) and 1997-2012 (group C). Nonparametric trend tests showed that 21% of the wells in group A, 36% wells in group B and 25% of the wells in group C had a statistically significant (p < 0.05) declining trend in the mean annual groundwater levels. Trend tests for rainfall and rainfall adjusted groundwater levels (locally weighted regression residuals) showed that rainfall variability could not fully explain the declining trends. Increase in numbers of irrigation wells (shallow and deep), as well as the irrigated area, were the main factors causing the decline in groundwater levels. The number of closed drilled wells increased from 61,236 in 1994 to 297,601 in 2007, an increase of almost 400%. The growth in number of tube wells has caused abandonment of many traditional open (dug) wells and reduced the productivity (area irrigated per well) of drilled wells. Continued increase in groundwater-based irrigated areas is likely to increase the groundwater level declines and well drying occurrences in the future. Supply and demand management of groundwater along with a transition to resource efficient techniques such as drip irrigation could reverse this decline and increase the water availability in the region. Low specific yield and low storage capacity of these shallow weathered fractured aquifers would continue to play an increasingly important role in planning, design and management of groundwater resources of the region.