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Habitat Observatory

    Rainwater Harvesting in Cholistan Desert of Pakistan
 

Background
About 70 million hectares of Pakistan fall under arid and semi-arid climate including desert land. Cholistan is one of the main deserts covering an area of 2.6 million hectares where water scarcity is the fundamental problem for human and livestock population as most of the groundwater is highly saline. Rainfall is the only freshwater source, which occurs mostly during monsoon (July to September). Therefore, rainwater harvesting in the desert has crucial importance.

The Pakistan Council of Research in Water Resources (PCRWR) has been conducting research studies on rainwater harvesting since 1989 in the Cholistan desert by developing catchments through various techniques and constructing ponds with different storage capacities ranging between 3000 and 15000 m3.

These ponds have been designed to collect maximum rainwater within the shortest possible time and to minimise seepage and evaporation losses. As a result of successful field research on rainwater harvesting system, PCRWR has developed 92 rainwater harvesting systems on pilot scale in Cholistan desert. All these pilot activities to harvest rain have brought revolution in the socio-economic uplift of the community. These activities have also saved million of rupees during the recent drought. Large scale adoption of all these interventions would ultimately help improve the socio-economic conditions of the residents of hyper arid area of the country.

Development of Raineater Harvesting System
As a result of field research on rainwater harvesting techniques, PCRWR initiated a 4-year Research and Development (R&D) Programme in 2001 to make water available in the desert for drinking. The activities were undertaken including reconnaissance survey to identify the suitable catchments, demographic survey to assess water demands, hydrological studies to assess the runoff potential of the catchment, topographic survey to determine the slope for runoff; development of catchments to establish a network of ditches, soil profile investigations to determine physical and chemical properties of the  catchment/pond, design analysis of rainwater harvesting system to estimate the quantity of civil works.

Collection of Rainwater

Alive to the problems faced by the population in the desert, 92 rainwater-harvesting systems have been developed on pilot scale. Each system contains the components like storage reservoir, energy dissipater (stair), boundary wall, silting basin, lined channel, and ditches network in the catchment.

The storage pond is designed to collect about 15000 m3 (4.0 US million gallon) of water. The depth of the pond is 6 m. Polyethylene sheet (0.127 mm) on bed and plastering of slag mortar (3.81 cm) mixture of clay, quick lime, wheat straw and cement on sides of the pond have been provided to minimise seepage losses. The quantity of the mortar for one pond includes 6 m3 clay, 100 kg lime, 970 kg wheat straw, and 0.06 m3 cement.

The energy dissipater having dimensions of 1 m wide and 23 cm each length and height along one side of the pond protects the sides and the bed of the pond from severe erosion expected from gushy water.

Boundary wall does not only restrict the wild animals and livestock but also provides barrier against movement of sand by strong summer winds. A small silting basin controls the entrance of heavy sediments and debris in the pond. Each pond has been connected with the catchment through a lined channel, which has a network of ditches. It has been observed that all the constructed ponds get filled up to their full design capacity during the rainy seasons (winter or monsoon). Water quality analysis of the selected ponds illustrated that the water quality was within the permissible limits excluding turbidity level. In general practice, the livestock drink water from the pond directly. However, the dwellers keep this water in mud pot for few hours by adding alum treatment before drinking.

Impacts of the Rainwater Harvesting Project
All these pilot activities have brought about revolution by creating awareness among the desert people and the concerned development agencies working in the area. This project has harvested about 368 million gallons of freshwater annually to meet drinking water requirements of human and livestock population. Moreover, this project has saved 6000 million rupees per drought in the form of livestock production due to reduction in livestock migration, mortality, diseases and damage of crops. Increase in production of livestock has also been observed in the form of meat, milk and other utilities besides reduction of migration of human and livestock from desert towards irrigated area.

Conclusions and Recommendations
Following were the conclusions and recommendations that emerged from the project:

  • Out of 350 Mm3 of runoff potential, 1.35 Mm3 has been harnessed successfully through scientifically designed 92 pilot rainwater harvesting systems. The remaining potential can easily be exploited through adopting rainwater harvesting strategy developed and tested by PCRWR
  • About 368 million gallons of freshwater is economically made available through out the year against. However, maintenance of the system by local people is recommended to make it sustainable;
  • There is still need to carry out research endeavors to evolve the cheapest method for reducing evaporation and seepage losses from the ponds.

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    Nothing succeeds like success – (A success story in making)
 

Village Somonathpur in district Balasore is one of the many villages where the Total Sanitation Campaign (TSC) is being implemented. The village comprises 487 households, including 86 APL households. Despite initial setbacks, DWSM persistent efforts have finally paid off and more and more households are now committing to the cause of sanitation. Presently, approximately 10 per cent of the total households covered have purchased 10 to 15 extra rings for the construction of upgraded toilets. Of these households, more than 10 households have already constructed the toilets.
This is definitely a positive influence on those who have yet to adopt safe sanitation practices. It is a good beginning and efforts are on to replicate the programme at the Panchayat level.
For more details please visit: http://www.ddws.nic.in/popups/IntegratedAprroach-Balasore.pdf