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Remote Sensing and GIS application in delineation and management of wastelands in Indira Gandhi Nahar Project (IGNP) command area
Balak Ram
Central Arid Zone Research Institute
Jodhpur
bram@cazri.raj.nic.in
Introduction
Indira Gandhi canal has transformed northern part of Arid Rajasthan into Green and Granary. But excessive irrigation and intensification of agriculture over the years has caused environmental degradation and creation of new wastelands. In order to restore and save these limited and precious land resources from further degradation, their proper identification and mapping is a pre-requisite. The recently developed remote sensing and GIS technologies and availability of better resolution data, has revolutionised the mapping of wastelands and other natural resources. In the present study the wastelands of Hanumangarh district, Rajasthan have been delineated and mapped on 1:50,000 scale through visual interpretation of IRS-IC LISS-III geocoded data supported with field survey. Toposheet wise three layers viz. base and watershed, administrative and wasteland were prepared. These maps have been digitized and digital ( vector ) data base has been created under GIS environment under the line of NRIS. Spatial distribution, characteristics and present status of different wastelands as well as their image characteristics are discussed. Technologies / measures are suggested for rehabilitation and development of different categories of wasteland in order to put them into a sustainable production systems.
Location and Environment
Hanumangarh, the northern most district of Rajasthan with a total geographical area of 970315 ha is located between 28°46’30" to 29°57’20" north latitudes and between 73°49’55" to 75°31’32" east longitudes. It is surrounded by Ganganagar district in the west; Bikaner and Churu districts towards south west and south; Sirsa district of Haryana in the east and Firozepur district of Punjab in the north. The district has 6 towns and 1906 villages with a total population of 12,20,333 (645205 males and 575128 females) as per 1991 census. 82.14% of the district population live in rural area while 17.86% live in urban area. Thus density of population comes to 127 person/sq km and a literacy of 30.99% (Anon.1996). The district has a livestock population of 12.48 lakh as per 1997 census (Anon.1998). Climate of the district is hot arid. The mean maximum and minimum temperatures are 43.03° and 5.05°C respectively. Mean annual rainfall is 281 mm with a coefficient of variation (cv) of 50% and probable maximum precipitation (PMP) of 45 cm. This varies from 350 mm to 225 mm with a decreasing trend from SE to NW.The northern part of the district is chiefly Ghaggar flood plain with thick layer of alluvium and blown sand. Southern part on the other hand, is characterised by sand dunes and interdunal plains. The relative height of the sand dunes reaches upto 50 metres. Ghaggar river which is also known as “Nalee” is an ephemeral one and has NE to SW course near Hanumangarh. It sometimes get flooded during monsoon and causes extensive damage of crops and property. Soils of this region are deep to very deep with fine to coarse texture. Northern irrigated Ghaggar plain is dominated by fine and moderately fine textured soils. In southern rainfed zone the major soil groups are sandy to loamy sand at places underlained by lime concretion and gypsiferous substrata. The surface is covered with sand hummocks and sand dunes. The soils are low in nitrogen, organic carbon and phosphorus contents. Clay to clay loam soils are encountered with accumulation in sub strata along the Ghaggar bed.
Method and Materials
The methodology of wastelands classification system, interpretation of satellite data and preparation of wasteland maps, is same as adopted by NRSA. Similarly, the methodology for preparation of wastelands digital (vector) data base in GIS environment has also been followed as per manual prepared by NRSA (1997 & 1998). Wasteland layer of all 23 effective toposheets were prepared through visual interpretation of IRS IC LISS-III geocoded FCC imagery (on 1:50,000 scale) of Ist and 20th February, 1997 and also IRS IB LISS-II geocoded FCC of January, 1995. Boundaries of different wasteland categories were verified and checked during the field survey. The same were finalised after considering the tehsil-wise land use data for 1997-98 and farmer’s opinion.
Toposheet wise all the above three layers so prepared were digitized. Thereafter using ARC/INFO GIS system their editing, labelling, projection, transformation, edge matching and overlaying processes were completed. Statistical output were then generated and after their verification and correction the same were quantified and final toposheet wise and watershed wise statistics were generated. The suggesstions to rehabilitate and develop different categories of wastelands are based on the technologies developed by CAZRI and other research organizations.
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