Water Management Of The Thar Desert Environmental Sciences Essay

The Thar Desert, also known at the Indian Desert is located partly in Rajasthan state, northwestern India, Punjab province, Sindh province and eastern Pakistan in Asia. (Britannica) Its precise location is between latitudes 24° and 28° north and between longitude 68°and 71° east. (Irrigation) This desert is considered one of the smallest hot deserts in the world only, 77,000 square miles (200,000km²) (Britannica) yet it has the highest human population of all deserts in the world. (Kuma) Other deserts have a population density of less than ten people per square kilometer, while Thar has a density of more than eighty people per square kilometer. (BBC) With such a large population which continues to grow, it can put a great strain on the environment and the resources it provides. One very important resource that the environment provided is water. Water is the bases for life on Earth and without it humans would not be able to survive. Not only do humans demand water directly, they demand it indirectly for the growth of their livestock and crops. Water management in the Thar Desert has to be constantly looked after to ensure that the supply of water will always be present.

There are three main ways to get water in the Thar Desert. First, is the rainfall distribution. Second is the terrain type. Third is importing water from outside the area. (Dhir) All of the water management techniques that the Thar people use can be categorized into one of these ways. No one individual method of obtaining water is fully effective by itself. It takes a combination of many techniques to keep a water supply that can sustain the people who are using it. Some techniques rely solely on the weather conditions in a given year and can fluxuate from year to year and are not always dependable. This is why multiple techniques are used to obtain water, in case one fails there are others to fall back on.

The soils in the Thar Desert does not allow for water to remain at the ground surface. The soil is made up of loose and porous sand. This allows for the rainwater to quickly be absorbed by the soil and any extra water moves straight down to the ground water reservoirs, via percolation. Unless the water is captured before it hits the soil’s surface or contained in something at the surface there is no way to access it without going into the ground water reservoirs. (Irrigation) Capturing rain water would be much easier if more of it came to the Thar Desert. The rainfall that is received is relatively low. In the west, the desert receives 4 inches or less of rain fall and in the east about 20 inches of rainfall. (Britannica) The amount of rainfall an area gets is dependent upon where it is located. The rain is sporadic in most parts. Up to nine-tenths of the rain received by the Thar Desert comes between June and September which is the monsoon season. (Agrican and Irrigation)

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Due to the fluxuation in rain, in regards to when it arrives, it causes agriculture to fluxuate with it. Before the rains arrive the land production is very poor and after the rains have arrived the land is very productive. In a sense the rainfall determines whether or not there will be an opportunity to grow crops effectively. The more rainfall means there is more availability for crop production and the less rainfall means there is less availability for crop production. “After a good rainfall when the desert is full of nutrients and succulent grasses a large number of cattle from the Nara Valley in Pakistan and adjoining areas come to graze in the desert.” (Irrigation) Herders also take advantage of the rainfall and move their cattle to areas where the grasses are plentiful and nutritious. When there is not a good rainfall herders must find others areas to grazer their cattle which might include irrigated areas. Other ways to make use of the monsoon rains are to cultivate patches of land that is suitable in the low ground. These low grounds are found between sand-mounds (talis, tals or dhars). When the rains are deemed adequate for cultivating crops these areas are taken advantage of.

Budgeting the water can be an effective way to manage the water that is available and relate it to the potential crop production it could yield. A formula was derived consisting of four variables: “the availability of reserve supply of soil profile moisture (M), in a given period varies under the influence of rainfall (P), runoff (S), percolation (U) and evapotranspiration (ET).” (Sen) The equation for the balance of water is P = S ± M ± U + ET. Water budget studies have shown that evapotranspiration accounts for 75-80 percent of the rainfall, percolation accounts for 5-10 percent, and 10-15 percent of the rainfall contributed to increasing the moisture of the soil profile when there is no water going to run-off. Techniques used to balance water on an agricultural farm in the Thar Desert include improving infiltration, deep percolation, control of evapotranspiration, and harvesting run-off. Infiltration can be done by bunding, shattering of hard pan or preparatory tillage. Deep percolation can be improved by soil compaction. Improving the control over evapotranspiration can be established by control of evaporation. Harvesting run-off can be improved by inter-plot water harvesting or inter-row water harvesting. By improving the means of which water is budgeted can cause the water that is acquired to be used more effectively for farming practices instead of being acquired by the land where is becomes more difficult to obtain.

Irrigation is a means of importing water in from another area and can be used in combination with water budgeting of the rain fall of an area. It is the main way that the people of the Thar support their agriculture. Between 1951 and 1980 there were at least 1,127 irrigation projects that were classified as major or medium that were taken up. Of the 1,127 projects 506 were complete, 17 were almost completed and the others were yielding partial benefits. (Prakash) There was a goal set to achieve 1,130 lakh hectares of grass irrigation potential which was the assessed target. This goal caused an increase in the development of policy for implementing irrigation projects. Irrigation projects have been going on in the Thar Desert long before the 1950s. The Gang Canal Project was started in 1920 and completed in 1928. The project consisted of the construction of a canal that would irrigate the north western part of Ganganagar and have a total length of 1,251 km in Rajasthan. The Bikaner Canal would feed into the newly constructed Gang Canal and potentially provide water to the extent of cultural command area (CCA) of three 07,692 ha. (Kuma) This is just one irrigation project that was created and currently still operating in the Thar Desert.

Another irrigation project is the Indira Gandhi Nahar Pariyojana (IGNP). This project’s main goal was to “fetch the river water to the waste stretches of desert in western Rajasthan from the Himalayas.” (Kuma) The water would be diverted in Punjab from the Hari-ke-Barrage and travel to Rajasthan. This project started in 1958; one of the 1,127 projects developed and was considered a partial irrigation facility in 1961. The project was separated into two different stages. The first stage focused on the 0-74 km of the main canal and stage 2 focused on the 74-189 km of the main canal. The completion of this irrigation project would potential bring irrigation to “15.85 lakh hectare of semi-arid and arid desert wasteland in a cultural command area spanning across four districts of the Thar Desert of Rajasthan, namely Ganganager, Bikaner, Hanumangarh and Jaisalmer.” (Kuma) This project would help to irrigate almost the entire western side of Rajasthan by merely diverting the water from another area.

In the area of Nagaroarkar, specifically the inland section, the Sind government set up experiments to try to improve water availability. These experiments took place between 1968 and 1969 and possibly could have been included in the 1,127 irrigation projects. The Sind government developed six flood irrigation schemes and four tank construction schemes, Gordharo Bhatiani flood scheme, Ranpur Basin-cum-Inundation Scheme, Surachand Flood irrigation scheme and Bhodosar, Tobiriyo, Nabisar and Ghartiara tanks. (Irrigation) These experiments were successful and provided water reservoirs in these inland sections of Nagarparkar. The reservoirs were used for multiple months after the initial water was stored. The success of these experiments showed that ideas such as these need to be replicated and applied to other areas and try to increase the performance of the ideas. (Agrican and Irrigation)

Other areas in the Sind portion of the desert presented promising ideas for the improvement and development of water availability. One development was to repair the existing well and ponds that can be repaired and this action is suitable for the entire desert. A second development was to dig deeper wells and it is mostly suitable for areas along the aquifers in the central and eastern portion so the desert. A third development was to dig a canal from the Indus River which once completed would allow for more expansion of the canal system reaching a wider area. A fourth development was the collection of the rainwater in more effective ways specifically focused on the construction of reservoirs with supporting deep tube-wells. These four developments along with the expansion of the irrigation experiments were compiled in 1985 and fall into the three ways of obtaining water; rainfall, terrain and importing. So over the years since 1920 the development of irrigation projects and other means of acquiring water availability has been an ongoing process. (Agrican and Irrigation)

Besides irrigation systems there are also means of conserving what surface water is available from the rainfall. Surface water can be gathered in traditional nadis (small ponds), tankas (underground covered tanks) or khadins (water harvesting structures for agriculture). The nadis are one of the major sources of drinking water both for human and livestock consumption. The nadis are dug by villagers in locations that are deemed natural for catching water in higher yield potential. They are constructed to an optimum size, in dune areas from 1.5 meters to 4 meters and in sandy plain 3 meter to 12 meters, and their depth is typically to the zone of calcrete formation. The nadis are used for an entire village if possible and the water supply that is stored in them could last anywhere from two months to a year after the rains depending on the water usage of the villagers (Centre for Science and Environment). Tankas on the other hand might be owned by an individual family or by the community. Tankas are being replaced with pipe-water supplies now since they were mostly used in remote areas. (Dhir)

Tankas are underground tanks that are built within a main house or the courtyard of a house. They are constructed during the winter and summer seasons when there is available labor since people are not needed for agricultural labor during these seasons. The tanks consist of a hole dug into the ground about ten feet deep that is circular and is lined with fine polished lime. “The catchment area of about 30 feet radius is made sloping towards the tank inlet.” (Jhunjhunwala) In the tank rainwater is collected by means of gravity and it the rain falls directly into the tank. To keep the water that is collected cooler, they decorate the tankas with tiles. The water that is collected in the tankas is used for drinking water only for a single family. The water stored in the tank can last for six to nine months. In years when there is less rainfall the tankas can be filled by transporting water from nearby wells and tanks. This means of collecting rain water is used mostly in areas far from other water sources. The positive effects of tankas include the women not having to leave the home to obtain water, there is an assured supply of water for domestic use, the construction of a tankas is cheaper than paying for water and having to transport it, and having a tankas can be considered a means of social respect. The main negative effect of tankas is that they take up land that could otherwise be used for agriculture. (Centre for Science and Environment) (Jhunjhunwala)

Khadins are water harvesting structure used for agriculture. They are also known as dhora. Their purpose is to catch the surface runoff water. “Its main feature is a very long (100-300m) earthen embankment built across the lower hill slopes lying below gravelly uplans.” (Centre for Science and Environment) This allows the excess water to drain off and be gathered and used to on the land to assist with crop production.

http://www.rainwaterharvesting.org/Rural/img/Khadins-img.jpg

(http://www.rainwaterharvesting.org)

Water management all comes down to the techniques used and if they are effective in that specific area and if there an opportunity to apply the technique to other areas or possibly improve upon the technique. Projects and experiments have been used to establish these techniques in irrigation but they have the potential to be used to discover and improve upon techniques to manage rain fall. One example of an improvement made to a technique that is already practiced is the modification of tankas. The modification consists of collecting rain water from the roof and by means of pipes transports it into the tank for storage and later use. This allows the land that would be used to construct the tankas can be used for agricultural use. (Jhunjhunwala)

The water tank schemes that were tested by the Sind government were shown to be effective and tanks were implanted in other areas. The water tank is also known as johad and they provide water for both humans and cattle. They are constructed on public land and all of the people in the community have equal right to use the water in the johad, because of the common use of the johad they are often placed in areas not far from the majority of the people. To construct a johad the land has to be level and there must be clay soil so that the rain water will collect in the tank. The johad is made between January and June must be cleaned out every year as well. (Jhunjhunwala)

The source of water supply can be categorized into the three main sources. These sources are rainfall, ponds and wells. In some cases there might be lakes of water also available. The rain water is collect in tarias (ponds) which only last about three to nine months. Tarais are short lived because of their size, the amount of rain water received, how fast the water is evaporating and how permeable the layers beneath the water are. The water that is contained in the tarais is fresh and used for domestic purposes of drinking and cattle watering too. Tarais are very common, in fact most villages has a tarai. Tarais also have a positive effect; “their significant influence to the top seated aquifers, namely their water seeps slowly down to the ground water reservoir and freshens the brackish or saline in situ water, making it suitable for drinking and other purposes.” (Irrigation) Due to this positive effect wells are often dug close to tarais.

The wells are created to reach the water supply more effective. They provide almost 95% of the water that is required for an area. Wells that are built too shallow can cause problems through. They can turn brackish after time and this is a waste of money in the construction of shallow wells. (Agrican and Irrigation) The construction of a well consists of a wooden foundation in the bottom of the well in the shape of the wheel. The sides of the well are lined with green branches and brushwood in a wicker work formation. Depending on the localities in the interior of the well, such as wells between 40-100 meters, these well are lined with burnt bricks. (Irrigation)

Since there has been no systematic hydrogeological investigation in the Thar Desert, there is no way of knowing if all the aquifers that exist have been discovered and put to use. Aquifers are part of the terrain aspect of obtaining water. Aquifers horizons have been assumed to exist and are grouped into three categories. The shallowest aquifers have a water table depth between a few meters and 20 meters. The medium aquifers have water table depths between 20 meters and 50 meters. The deepest aquifers have water table depths between 50 meters and over 100 meters. It is believed that the deep aquifer is present in the central and eastern parts of the Thar Desert and might be continuous or discontinuous with a mono or multi-layered structure. In most parts of the aquifer the water quality is fresh to slightly brackish but some parts of the aquifer are severely brackish and unfit for use. (Irrigation)

Water in the Thar Desert is saris and a valued environmental resource. A great deal of effort has gone into designing developments, testing experiments and implementing projects to increase the water availability in the Thar Desert. The water is used for both domestic use and farming use for cattle and crops. Ideas and projects can always be built upon and improved to increase their effectiveness. Water management techniques can date back to at least the 1920s with the first project title but they occurred long before that time and they will continue to occur to support the Thar people’s way of life.