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abstract 703

Efficiency of artificial groundwater recharge by percolation tanks in a semi -arid hard rock aquifer context, South India.

Author(s): Sylvain Massuel, Jérome Perrin, Mohamed Wajid, Cédric Mascre, Subash Chandra, Benoit Dewandel
Sylvain Massuel1*, Jérome Perrin2, Mohamed Wajid3, Cédric Mascre2, Subash Chandra3, Benoit Dewandel4 1International Water Management Institute, c/o ICRISAT Patancheru 502 324 Andhra Pradesh, India 2BRGM, Indo-French Centre for Groundwater Research,

Keyword(s): groundwater recharge, percolation tanks, hard rock aquifer, sustainable water management, semi-arid climate, India

Article:

Poster:

Session: OS4e Infrastructure

AbstractABSTRACT

The Ground Water Department of Andhra Pradesh estimates the Stage of Groundwater

Development (SGD) as the groundwater utilization (Draft) divided by the groundwater potential (Availability).

According to this, the state of Andhra Pradesh is currently facing a general overuse of the groundwater resource,

mainly due to agriculture irrigation demand. As a measure to fight against groundwater overexploitation, the Central

Ground Water Board of India has promoted for the past 10 years the construction of percolation tanks or the

conversion of traditional water harvesting structures for irrigation into percolation tanks. Consequently, the number of

artificial structures for storing runoff water has exponentially increased during the last decade. Despite the many

artificial recharge programmes implemented in various Indian states, the impact of these measures has been little

scientifically studied with the notable exceptions of Sukhija et al. (1997) and more recently Sharda et al. (2006),

who estimate recharge efficiency of artificial tanks between 35% and 50% in hard rock aquifers. Some studies at a

local level suggest that artificial recharge may be negligible compared to the groundwater recharge whilst the amount

of surface water stored in artificial percolation tanks has large consequences on water inflows to the main surface

water reservoirs downstream. For instance, in the Musi basin, gross storage capacity of Osman Sagar and Himayath

Sagar reservoirs for Hyderabad city water supply has declined by 12% and 20% during the last three decades due

to upstream watershed development.
In the framework of the SUSTWATER Project (EuropeAid), the Gajwel

watershed (80 km2) categorized as Critical (90
Support Tool that simulates the impact of changing cropping patterns and artificial recharge on groundwater levels. In

the basin, 30 artificial percolation tanks have been identified. Their size ranges from 20 to 46 ha and covers

approximately 3% of the total basin area (2.5km2). The monitoring of a typical artificial percolation tank has been

carried out. The site has been instrumented with evaporation pan, rainfall gauges and water level recorders in the

tank and in one abandoned bore well in the vicinity. The topography of the tank has been accurately measured by

Differential GPS for determining the relation between the tank water level and the actual volume stored. Electric

sounding profiles have been interpreted for assessing the aquifer thickness and the siltation extent. Water samples

have been taken weekly in order to apply Sukhija et al. (1997) chloride method for evaporation estimate. Based on

these field data, it is possible to quantify the volumes of water respectively collected into the tank, lost by

evaporation, stored in the unsaturated zone, and recharging the groundwater. With some assumptions, it is possible

to use these results for an estimation of the artificial recharge efficiency at the watershed scale and to simulate some

future scenarios corresponding to different levels of watershed development.

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Efficiency of artificial groundwater recharge by percolation tanks in a semi -arid hard rock aquifer context, South India.