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Untapped groundwater

July 02, 2012

Tharparkar is the most water scarce region in Sindh. However, various researches confirm that there is plenty of untapped groundwater resources in the area.

Indeed, various initiatives have been taken to develop groundwater-resources in the region, but the water-crisis still remains unresolved and uncontrolled, perhaps more due to lack of systematic exploration and development of shallow and deep groundwater resources.

The economy and livelihood of Tharparkar heavily depends on rain-fed agriculture and livestock-rearing.

There are three main groundwater zones in Tharparkar. The base (deep) aquifer zone bellow the depth of 300 meters is with a substantial thickness of about 40 meters on an average (with tremendous potential of water resources), relatively with high permeability, high pressure head and large extension of more than 20,000 km² (extended near in entire Tharparkar).

The recharging (rain-infiltration) area of this zone is hilly Nangarparkar and south-eastern areas across the international border; as the regional gradient of this basement hilly zone is tended to north-west coming from south-east (Zaigham).

The annual rainfall in this recharging zone is also being recorded comparatively well up to 360mm in Nangarparkar and 1000mm in Udhaipur (Zaigham) and commendable annual recharge rate of up to 3.7 mm/year across the south-east of Nangarparkar region beyond the international border (Sazda report).

The middle aquifer which is composed of a variety of mainly disconnected sand lenses and channels with partly high silt content and low permeability within the lignite bearing Bara Formation and the Sub recent Formation with comparatively less recharge rate. While the third is the Dune Sand Formation zone which acts as a top aquifer with a water column of few meters at the formation base on top of the middle zone.

Recharge of this aquifer is direct through rainfall infiltration, mostly from northern areas of Tharparkar and adjacent to north districts; with tendency of north-east to south-west (as opposed to the base aquifer). The RWE water study calculates that only four kilometers of area in Tharparkar has its top water aquifer equal to around 50 m³/a/m, hence the annual permeability (water movement) can provide water from the same area of around 200,000m³/a.

On the basis of this calculation it is estimated that total (extractable) top water aquifer across 22,000 square km of Tharparkar is likely 110million m³/a. Thus, Sazda in 1989 calculated 44millionm³/a, the total water consumption need of Tharparkar. It is worth to note that more than 95 per cent of the entire current water needs of Tharparkar are being met by this top water aquifer without taking any appropriate measures on the recharging and development of this aquifer.

However, the untapped base (deep) aquifer of Tharparkar has ten-times more water-resource availability than the useable top aquifer with sweet, saline to brackish water quality and commendable recharging conditions. Moreover, the results of different pumping tests in Tharparkar also indicate nearly immediate recharge of aquifers and even after a longer pumping the quality of deep ground water aquifers improves (Zaigham).

Hence, as a part of likely upcoming coal mining in Tharpakar, the tremendous resources of groundwater are to be extracted anyhow- rather it is imperative to have a proper groundwater utilisation strategy advance in hand.

Based on the above findings and reasons, it is concluded that further specific studies on the subject should be conducted coincided with groundwater development initiatives/projects in northern (also in north parts of Tharparkar) and south-eastern (hilly Nangarparkar) Tharparkar. The findings also justify exploitation and judicious utilisation of the tremendous potential of untapped deep aquifers for wider socio-economic development including agriculture, forestry/rangelands, livestock, horticulture and industries.