Hydrogeological characterization and hydrological modeling for devising
groundwater management strategies for Chennai aquifer system, Southern
India
Abstract
Chennai aquifer system covering an area of 6629 km2 is one of the most
stressed aquifer systems in southern India as groundwater is
relentlessly used for irrigation, domestic, industrial purposes and for
drinking water supply to ever expanding Chennai city. This heavy
extraction necessitated a paradigm shift towards groundwater management.
Multidisplinary-integrated approach was taken up to map the aquifers,
delineate its geometry, hydrodynamic characterization and to formulate
an aquifer management plan through groundwater model. Weathered &
fractures gneiss/charnockites along with alluvium form the aquifer
units. Alluvium is the potential aquifer system of the region with
potable quality except for the eastern/northeastern region affected by
to seawater intrusion. Two-layered hydrogeological model was developed
with one km2 grid pattern to simulate groundwater flow for nine years.
The model calibrated under steady and transient conditions, allows
quantifying the components of recharge, groundwater draft, and fluxes on
the regional scale. Simulated results indicate that this aquifer system
is under tremendous stress with the present groundwater withdrawal of
899 mcm and becomes unstable with 25 % increase in groundwater
withdrawal by 2025. 54 mcm increase in resources due to recharge
measures has groundwater head build up and easterly movement of the
potential lines. Scenario of maintaining 120 days flow in rivers shows
increase in groundwater head and development of the groundwater mounds,
which are positive signatures for arresting the decline and pushing the
saline water. Regulation of groundwater abstraction and rejuvenation
flow in the rivers would sustainably manage the available groundwater
resources of the region.