Quantification of trends in groundwater levels of Gujarat in western India

The patterns in groundwater level, rainfall and temperature extremes for the western Indian state of Gujarat were examined using water-table records of 555 monitoring wells and daily rainfall and maximum temperature data sets for the period 1995-2005. The results reveal a large number of declining trends in groundwater levels with notable spatial structures; these are unlikely to be associated with the natural climate variability. There is also a noticeable increase in the temperature and rainfall extremes. Our results suggest that the groundwater withdrawal has increased, perhaps due to recurrent droughts and increases in temperature, and this has caused widespread water-table decline that has not been countered by rainfall extremes. Rainfall extremes appear to have caused greater runoff losses in the humid and sub-humid coastal regions, whereas the aquifers of the arid and semi-arid northern regions are more vulnerable to droughts and the warming environment.