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Parts of Thar Desert, Rajasthan
 
Background Information
Climate
The area has a dry climate and falls in the Arid zone. It is classified as ‘lc’ zone, as per the agroclimatic classification of Rajasthan (Rajasthan Agricultural Statistics).
Rainfall is erratic and normal annual rainfall in Jaisalmer district is 181 mm. Season-wise rainfall in 2010-2011 is detailed below.
(in mm)
Annual Normal June ’10 – Sep ‘10 Oct ’10 – Dec ‘10` Jan ’11 – Feb ‘11 March ’11 - May ‘11 Total (June ’10 to May ’11) % Deviation from Normal
181.2 361.2 11.3 5.0 3.0 380.8 110.20
The annual maximum potential evapotranspiration in the district is 1850 mm and it is highest in the month of June and lowest in the month of December.
Physiography
The Pilot study area forms part of extensive Thar Desert area of Rajasthan. The major part of the study area is predominantly covered with flat, limestone terrain. There is little or no soil cover and thin vegetation.
Drainage
There is no well-developed drainage in the area. The area is part of Barmer sub-basin in the Indus River Basin.
Geomorphology
The main landforms in this area are desert sand dunes of Aeolian origin. They are the more dominating geomorphic features in the western & northern parts of the study area. The sand dunes are longitudinal (NNE-SSW) and mostly stabilised in nature with sporadic vegetation. At few places, these are covered with second set of sand dunes. These second set is mostly of Barchan type sand dunes.
 
Figure 5.4: Stabilised Sand Dunes.
 
Figure 5.5: Barchan Sand dunes on the stabilised old sand dunes.
 
Soils
The soils in this area are mostly desert soils, aeolin soils. They are loamy, coarse in texture and calcareous.
It is planned to conduct infiltration tests in different soils with different proportions of clay, sand, etc. and in different land use conditions including canal command area to estimate the infiltration from different water sources.
 
Land use
Land use in Jaisalmer District (2010) is detailed below. Most of the land is culturable waste.
(area in hectares)
Area under non-agriculture use Barren and unculturable land Culturable waste land Current fallows Other Fallows Forest Land under Misc. tree crops and groves Net Area sown Permanent pastures and other grazing Total geographical area
147,437 363,715 2,347,402 41,570 64,543 44,873 298 725,685 103,631 3,839,154
Source : www.data.gov.in
 
The net sown area represents about 18% of the district area. The land used for irrigation is only about 2.7%.
The area under irrigated agriculture includes irrigation by IGNP canals and tube wells. Details of irrigation in Jaisalmer district are in the following Table.
(in hectares)
  IGNP Tubewell Other wells Other sources Total
Gross irrigated area 153,147 55,654 428 10 209,239
Net irrigated area 71,683 34,060 428 10 106,181
(source : Rajasthan Agriculture Statistics – At a Glance for the year 2010 – 11)
 
Figure 5.6: Canal system in and around study area.
Source : CGWB
 
Geology
The general geological succession in Jaisalmer district is as follows:
Age Formation and Lithology
Quaternary (Pleistocene to Recent) Aeolian sand & alluvium, gravel sand , silt, kankar & clay
Tertiary Sanu sandstone, Bandha and Khuiala limestone
Mesozoic Lathi, Jaisalmer, Baisakhi, Bhadesar, Parewar, Abur formation - Sandstone, shales with intercalated limestone, siltstone, clay stone
Proterozoic (Post Delhi) Granite
Most of the study area is underlain by limestones, covered by alluvium and sand dunes.