Rainwater harvesting or collecting system is the technology that collects and stores rainwater for human use. The infrastructure can vary from simple and inexpensive to complex and expensive. It consists of simple rain barrels, or more elaborate structures with pumps, tanks, and purification systems. The non-potable water can be used to irrigate landscapes, flush toilets, wash cars, launder clothes, and it can even be purified for human consumption.

Pakistan has been facing rapid climate change since last few years and the water resources of the country are at extremely vulnerable state. Water scarcity is the principal issue in most of the developed cities of Pakistan. Rainwater Harvesting (RWH), a famous technique that has been practiced for hundreds of years.

It is a method for accumulating and saving rainwater from various elements such as rooftops, surface runoff, and other catchments.  Harvested water can be used for all domestic purposes like drinking water, cooking and washing etc. Moreover, this harvested water has a potential to meet agricultural and crop’s water needs according to the available economy, the storage can be managed either on-surface or sub-surface

Pakistan’s first urban rainwater harvesting system has been installed in the capital city Islamabad, the Daily Times reports. The collection tanks at the Faisal Mosque complex were funded by the city’s Capital Development Authority, and will provide clean drinking water while recharging the local water table for the city’s nearly 1 million residents.

Known as the Pilot Rainwater Harvesting Project, the initiative was developed in collaboration with the United Nations Development Program and the Pakistan Council of Research for Water Resources.

Pakistan is currently going through its worst water crisis due to being prone to natural disasters, demographical changes, and massive urbanization. This increase in migration toward urban areas is disrupting natural ecosystems which will ultimately increase the demand for household water in the country. According to the information by international agencies, water stress is increasing in Pakistan and for a country whose economy is highly dependent on agriculture, the situation appears alarming.

There are several sources of water for the country with 60% of the total rainwater coming from monsoon rains. Many glaciers feed the river system in Pakistan but the glacial melt off increases the risks of flooding. Moreover, the river Indus and its tributaries provide most of the water needed for irrigation in Pakistan.

Furthermore, the treated rainwater needs to be stored for its efficient use. In urban and rural areas, there exist vast opportunities to store rainwater by constructing rain-harvesting infrastructure by utilizing dry ponds, canals, and low-lying areas. Thus, during heavy rainfalls, such as those in monsoon, when rivers and canals overflow, extra water could be preserved in specially constructed dams, reservoirs, and underground tanks. This would not only prevent flooding of the urban areas in future, but also conserve the water for later use in times of crisis.

Rainwater Harvesting in Cholistan Desert

According to research collaborated by the Climate Change Adaptation Project of the World Wide Fund for Nature-Pakistan; “There is a dire need to utilize rainwater, particularly in the arid zones like Kohistan, Thar, Thal, and Cholistan for agriculture and livestock purposes. Groundwater in arid areas is mostly saline, and therefore, cannot be used”.

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 source of 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) Regional office Bahawalpur 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 minimize 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. Each system consists of storage reservoir, energy dissipater, silting basin, lined channel, and network of ditches in the watershed.

Rainwater should be harvested and stored by making earth medium size reservoirs. Rainwater from these ponds can be utilized efficiently for drinking and irrigating plants. These ponds have been designed to catch maximum rainwater within shortest possible time and avoiding maximum water losses. Each pond has been connected with the main catchment area through the main channel and network of ditches connecting all lowest points in the catchment area via small ponds to de-load rainwater from soil materials before reaching in the ponds. The rainwater stored in these ponds is utilized by the local Dingarh and surrounding area people (more than 1500 in number) for drinking. The water is taken by the women of the village and nomads clustered around the ponds during shortage of water.

Freshwater is a (very) limited resource in the world. Most of the water available for irrigation comes from aquifers (groundwater) and lakes. The total amount of fresh water from these two resources only accounts for less than 1% of the total water supply.
Traditional farming techniques use fresh water for irrigation, putting a heavy demand on the world’s already scarce fresh water supplies. In fact, of all the water in the world, only 1% is fresh water, of which 70% is used for agriculture.
People have long believed that salt-affected land was unusable. But as a result of in-depth research and years of testing, a practical solution was found i.e. Saline agriculture. It is very well possible to grow various plant species combined with alternative techniques in irrigation, fertilization and water management.
The available groundwater in Cholistan Desert is 80-90 % of saline quality but the utilization of this saline groundwater is zero. Keeping in view the importance of saline horticulture in Cholistan Desert, Pakistan Council of Research in Water Resources install two solar powered turbines at its Field Research Station Din Garh, Cholistan. The groundwater, having quality 4500 µS/m, is being used for the irrigation of the various plant species through drip irrigation system.

Rangeland management is a professional natural science that centers around the study of rangelands and the “conservation and sustainable management (of Arid-Lands) for the benefit of current societies and future generations”. The protecting role of vegetation is the basis for many measures of erosion control, soil conservation, and rangeland management. Vegetation cover reduces splash erosion due to interception of rainfall, decreases overland flow, and improves infiltration of precipitation and runoff water into the soil.

Many rangelands are also subject to grazing by wildlife (Holechek et al., 2004). Therefore, consideration must be given to wildlife as a factor in rangeland management, especially regarding stocking rates, to ensure the conservation of rangeland productivity. Because non-game wildlife species impact forage resources, stocking rates should be adapted to occurring wildlife density (Niamir-Fuller et al., 2012). Conservative strategies to improve rangeland condition and wildlife habitat have attracted increasing interest as society has changed (Holechek et al., 2004).

Proper rangeland management includes good stewardship of the rangeland biological components to preserve soil health and soil conservation. Certain management practices can also contribute to a host of soil-related problems (e.g., excessive wind and water erosion, nutrient loading, and increased sedimentation in reservoirs), ultimately leading to a general reduction in the land’s ability to sustain healthy rangeland systems. Many of these problems can be avoided by the proper management of the aboveground or biological component of the range. While the concept of managing a healthy rangeland may seem simple and straightforward, different definitions of what constitutes a healthy rangeland result in divergent management approaches.

Water and fodder are the basic needs of Cholistani People for livestock rearing. With the efforts of PCRWR and CDA for rainwater harvesting the issue of the availability of drinking water has been almost resolved. However, the availability of fodder is still question mark. Due to long drought spell since last decade and over grazing practices, the rangelands have been exhausted. The carrying capacity of rangelands has been reached at very low level. Grasses are grazed before their maturity, hence seeding process has been stopped, it is very dangerous if local species of grasses are totally vanished. PCRWR has taken step to conserve and promote the seed bank of local grasses. For this purpose, 30 acres of desert land at Field Research Station Dingarh have been fenced to control to free grazing of Cholistan livestock. Where different local species of grasses and bushes like gorkha, bukhra, gandil, lumb, dhaman, phale, karir, phog were grasses to develop rangeland and seed bank.

C. FUEL PLANTS

i. DESI KIKAR (Accacianilotica):- This is a medium sized, thorny, nearly ever green tree that can reach a height of 20 – 25 meters. Desi kikar is popular as agroforestry tree. This is a multi purpose tree, widely used as timber, source of fodder for camels, goats and sheep, as a fence, shed and fuel tree. At Field Research Station Dingarh, 200 Nos desi kikar were transplanted. Conjunctive use of irrigation water (rainwater collected in pond and ground saline water) is being used for irrigation

ii. PARKINSONIA (Parkinsonia aculeata):- Parkinsoia is a small evergreen spiny tree and can grow in any soil. It is used for fire wood, leaves and pods used as fodder for goats and sheeps, it is a source of shed in desert environment. It is useful in soil stabilization as a wind break and erosion control and reforestation in sandy areas. 200 No. nursery plants of parkinsonia transplanted in the experimental area.