APPLICATIONS OF REMOTE SENSING FOR ELUCIDATE THE PALAEOCHANNELS IN AN EXTENDED THAR DESERT, WESTERN RAJASTHAN

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1 APPLICATIONS OF REMOTE SENSING FOR ELUCIDATE THE PALAEOCHANNELS IN AN EXTENDED THAR DESERT, WESTERN RAJASTHAN M. Rajesh Kumar*, A.S. Rajawat** and T.N. Singh* *Department of Earth Sciences, Indian Institute of Technology, Bombay **Space Applications Centre (ISRO), Ahmedabad ABSTRACT Climatic changes and neotectonic movements have led to migration and abandonment of several rivers and drainage systems, which were main source of water in the past. Some of them are extinct because of the continuous deposition of sand and silt on the channels. Although, several evidences left by them usually to help in proving the existence of a geomorphic features in a particular location. In India, in Western Rajasthan, the tributaries of Luni river reflects such fascinating features, supported by geological, hydrological evidences which are supported by the most modern tools, such as remote sensing and digital image processing techniques. With the aid of remote sensing through orbiting satellites the history of the river more or less solved. The study will open in challenges to recreate the path of the channels for solving the water problem in this state where water budget is in deficits. Key words: Remote sensing, palaeochannels, digital image processing techniques, and ERDAS- (8.5) INTRODUCTION Thar Desert or Great Indian Desert contains extensive region of sandy desert in northwestern India and eastern Pakistan (Fig.1). The desert is bounded on the northwest by the Sutlej river, on the east by the Aravalli range, on the south by the salt marsh known as the Rann of Kutch, and on the west by the Indus Valley. The largest part of the desert is located in Rajasthan state, India. The Thar desert is about 805 km (about 500 mi) long and about 485 km (about 300 mi) wide. The terrain consists mainly of rolling sandy hills, which mainly shows scattered growths of shrub and rock outcroppings. The altitude ranges from about 457 m (about 1500 ft) in the lower reaches of the Aravallis to about 61 m (about 200 ft) near the Rann of Kutch. Rainfall is sparse, averaging from 127 to 254 mm (5 to 10 in) annually, and temperatures rise as high as 52.8 C (127 F) in the month of July. Map India

2 Fig. 1 Location map showing Thar Desert, India. Major parts of Western Rajasthan are covered by aeolian and alluvium sand and are devoid of any perennial drainage system. The entire region is covered by poorly organized drainage systems. Luni basin is the only basin which can be easily delineated towards its eastern parts due to Aravalli hills and with some difficulty due to aeolian plains towards its Western parts. Otherwise, most of the region is covered by small isolated drainages that are lost in the surrounding sand dunes or aeolian plains. A large number of investigators have utilized remote sensing techniques to study the arid terrain of Western Rajasthan since last three to four decades. Useful reviews of such works have been made by Sahai (1993). However, it is observed that geological applications of remote sensing data in arid terrain have focused mostly on ground water applications and in particular on exploring palaeochannels and causes of river migrations. It is observed that Late Quaternary climatic changes and neotectonics have played a significant role in modifying the drainage courses in this part and a large number of palaeochannels exist. Study of lineaments in conjunction with palaeochannels provided extremely useful information. Often lineament controlled palaeochannels yield more groundwater. The applied and useful aspects of such studies for groundwater exploration to understand the groundwater prospective zones or the suitable sites for artificial recharge or in studies related to the palaeoclimate, Quaternary geology, archaeological exploration and seismic hazard zonations. Map India

3 However, the major problem in using remote sensing techniques is due to aeolian sand cover, providing almost uniform reflectance in optical images, and obliteration of the signatures due to human-induced land cover changes (conversion of land into agricultural fields, digging of canal systems, human settlements, etc.). ROLL OF REMOTE SENSING Satellite data has advantages of synoptic view, multispectral and multitemporal nature. Useful landforms like palaeochannels in arid regions are sometimes as wide as 6-8 km and their length may be of the order of hundreds of km. It becomes intricate to visualize their presence in field due to agricultural fields, or soil cover e.g., palaeochannel of lost Sarasvati, observed in the northern parts of Rajasthan and Haryana along the bed of current Ghaggara river. Landsat MSS, TM, IRS LISS-II and LISS-III data in the visible and near infra red region of the electromagnetic spectrum have been extensively utilized to categorize palaeochannels in northwest India and adjoining parts of Pakistan (Snelgrove, 1979; Ghose et al., 1978, 79, 80; Yashpal et al, 1980; Bakliwal and Sharma, 1980; Sood and Sahai, 1983; Kar and Ghose, 1984; Grover and Bakliwal, 1985; Anonymous a and b, 1986; Bakliwal and Grover, 1988; Kar, 1986, 88, 89, 93, 94; Raghav and Grover, 1991; Tiwari, 1992; Sharma et al, 1992; Sahai et al, 1993; Ramasamy et al. 1991, Ramasamy, 1999 and Rajawat et al, 1999 a & b). Most of the studies have in one way or the other linked these palaeochannels with Sarasvati, a mighty perennial river, which flowed from the Himalayas to the Arabian Sea through the present states of Punjab, Haryana, Rajasthan, former State of Bahawalpur (Pakistan) and Sind (Pakistan). Most of the authors have the same opinion with the palaeochannels of the Saravati coinciding with the bed of present day Ghaggara and believe that the Satluj along with the Yamuna once flowed into the present Ghaggara riverbed. It is postulated that the Sutlej is the main tributary of the Ghaggara and that subsequently the tectonic movements might have forced the Satluj westwards, the Yamuna eastwards and the Ghaggara dried. There are divergent views regarding the courses of the Sarasvati river in Western Rajasthan. Ghose et al. (1978, 79,& 80) have observed that the Luni a tributary to the Himalayan river Sarasvati and the confluence of these two rivers was at Pachpadra, where the Luni takes a sharp right angular bend towards the south. It was suggested that the Sarasvati river system was forced to shift its course westwards at least four times by aeolian sand advance from the southwest. These migrated courses are: (1) Nohar-Surjansar-Samrau-Pachpadra (2) Sirsa- Lunkaransar- Bikaner-Samrau-Pachpadra, (3) Rangmahal-Suratgarh-Anupgarh-Sakhi-Hakra/Nara, (4) Jakhal- Sirsa-Hanumangarh-Pilibangan-Suratgarh-Anupgarh-Sakhi-Hakra/Nara, and (5) Anupgarh-Fort Abbas. However, Sood and Sahai, 1983 do not agree with palaeochannels of Sarasvati connecting with the present day Luni and are of the opinion that Luni river system has independent drainage system. They attribute shifting of palaeochannels in north-west India to be primarily due to the tectonic causes and aeolian activity as secondary cause. Ramasamy et al. (1991) have interpreted the palaeochannels of entire Western India using Landsat data, interpreted the same with regional lineament fabric (Bakiliwal & Ramasamy, 1987) and brought out the Quaternary tectonic cartoon of Western India. Map India

4 Ramasamy (1991) has analysed the pattern of the palaeochannels of Sarasvati river system in Great Indian desert and classified them as: Organized near rectilinear palaeochannels, Disorganized convergent palaeochannels, and Sprayed palaeochannels. Such multivariate pattern has been attributed by them to be the effect of active tectonism along NW-SE and ENE-WSW faults. Palaeochannels can also provide information about the response of catchments and rivers to past climatic changes, with implications for projected changes to climate in the future. For this purpose, the climate records were derived independently from systems to establish link between climate and its response (Williams et al., 1993). The knowledge about the timing of the transition from palaeochannel to modern fluvial activity is also critical. For example, if the transition from palaeochannel to modern river activity was caused by a reduction in effective precipitation, and thus river discharge, it is likely to have been synchronous in adjacent subcatchments because of their proximity. MATERIALS USED IRS-1C LISS III data (CDs) were analysed in the present study. Table -1 shows the data utilized in the present study. Table 1 Satellite Sensor Path Row Date of acquisition Type of product IRS-1C LISS-III October 13, 1998 Digital, CD IRS-1C LISS-III November 30, 1998 Digital, CD IRS-1C LISS-III October 08, 1998 Digital, CD IRS-1C LISS-III October 08, 1998 Digital, CD IRS-1C LISS-III October 03, 1998 Digital, CD IRS-1C LISS-III October 03, 1998 Digital, CD Map India

5 The characteristics of IRS-1C LISS-III sensors are given in the Table-2. Table 2 Salient Characteristics IRS-1C LISS-III Spectral channels Channel 1, nm Channel 2, nm Channel 3, nm Channel 4, nm Spatial resolution 23.5 m (Channel 1-3) 70.5 m (channel 4) Swath 148 km Quantization 8 bit Repeat cycle 24 days Launch date December 28, 1995 INTERPRETATION OF PALAEOCHANNELS ON SATELLITE IMAGES Palaeochannels represents the former stream courses along which water may flow for a short distance during rainy season making the internal drainage. Such channels on the surface are almost disconnected with the main streams. Such kind of channels has been traced on satellite image using digital image processing techniques using ERDAS (8.5) imagine software. Various enhancement techniques such as contrast enhancements, histogram equalization, principal component analysis, band rationing, edge enhancement, sobel filtering, etc. have been performed on the IRS-1C LISS III data to identifying the palaeochannels in the Thar desert. The extent of channel continuity has been traced on band 1 and band 2 of IRS-1C LISS III imagery by the typical light gray to white tone for the dry part and dark gray tone for the part with moisture and vegetation. On false color composite, the dry sections are indicated by their white to light greenish tone and the moist and vegetated sections by pinkish red tone. Several such channels have been identified along the tributaries of the Jawai-Sukri and the Luni rivers in the eastern part of the basin. It has been observed that in general the channels occupy the dissected pediments and get disorganized or extinct in the aeolian plain or dune complex. In the northern part of the basin these are represented by the former tributaries of the Mithri/Jojri river from its east and by an extensive network of the Jojri river from the NE of Jodhpur to west of Balotra (Fig.2). It Map India

6 interpreted on satellite data as light gray to white tone due to sand cover. Across this channel another palaeochannels has been found as alignment of vegetation. It has been appeared as red tone on the false color composite. In the northwestern sector, these are represented by the Lik river (Fig.3a &b). It has been recognized on the satellite data as light gray to white tone on the false color composite (321) and light pinkish tone on the principal component of 331. The Lik river due to its bed being heavily occupied by sand dunes is almost extinct at present (Kar, 1998). The other abandoned channels of importance occur in the central part of the basin in the region from about 15 km west of Bilara to about 15 km northwest of Jalore (Fig.3c&d). It has been interpreted on satellite data as light pinkish red tone on false color composition and dark reddish tone on the principal component of 321. Through, an upper sector of Luni is used to directly join the Sukri/Jawai river in the past (Kar, 1999). Extensive aquifer systems containing mostly fresh water have been formed along the palaeochannel belts, particularly along lineament controlled courses. The fresh water occurrence is because of the regular flushing of the channels during rainy season. Still, the water towards depth may be taken as brackish to saline. The promising aquifer in the channel belts of the Jojri in the Jodhpur district are being exploited for fresh water supply. The quality of water must be better in areas to the east of Jodhpur in the buried pediments if rhyolite and sandstone are fractured and criss-cross lineaments occur. The water reserves are also there in the northwestern part of the basin along the dry channels of the Lik river and in the channels in the vicinity of Thob-Balotra region. However, areas near the saline water depressions (ranns) formed at the junctions of the channels need to be excluded from exploitation due to saline water. The other promising channel belts, which can be exploited for fresh water exists to the east of Mithri / Jojri river in Jodhpur region, along the former course of the Luni river in the Pali-Jalore region and in the area between the Mithri and the Jawai rivers. Map India

7 False Colour Color Composite Band 22 Principal Component Analysis Histogram Equalization Fig. 2 Digital enhancements performed on IRS-1C LISS III for deciphering the palaeochannels Map India

8 a. False Color Composite b. Principal Component Analysis c. False Colour Composite d. Principal Component Analysis Fig. 3 Digital enhancements performed on IRS-1C LISS III for deciphering the palaeochannels Map India

9 CONCLUSION Remote sensing is widely useful for revealed the palaeochannels in the desert areas using various digital image processing techniques of satellite images. The present disorganized state of many streams in the Thar desert of Western Rajasthan has been attributed by many investigators to change in climate during Quaternary, and in the particular Holocene. The analysis of satellite images of the area, however, indicates a number of lineaments across the plains. Most cases drainage disappearance appears related to these lineaments. The pattern of drainage disorganization suggests that climate could at best be an associated factor, but not the primary one. ACKNOWLEDGEMENTS The authors extremely happy to express their sincere thanks to Dr. K. N. Shankara, Director, Space Applications Centre, ISRO, Shri R.J.K. Jain, Head, HRDD, SAC, and Dr. Shailesh Nayak, Group Director, Marine and Water Resources Group, Space Applications Centre, Ahmedabad for permitting us to work as SAC. REFERENCES Anon. (1986 a). Report on the Ground Water Potential Maps of Rajasthan (based on visual interpretation of Landsat Thematic Mapper data), Space Applications Centre (ISRO), Ahmedabad, July, 1986, 97 p. Anon. (1986 b). Report on the Groundwater Potential Maps of Drought Prone Areas of Gujarat (based on visual interpretation of Landsat Thematic Mapper Data), Space Applications Centre (ISRO), Ahmedabad, June, 1986, 36 p. Bakliwal, P.C. and Sharma, S.B. (1980). On the migration of the river Yamuna. Journal Geological Society of India, Vol. 21, Sept. 1980, pp Bakliwal, P.C. and Grover, A.K. (1988). Signature and migration of Sarasvati river in Thar desert, Western India. Rec. Geol. Surv. Ind. V 116, Pts. 3-8, pp Bakliwal, P.C. and Ramasamy, S.M. (1987). Lineament fabric of Rajasthan and Gujarat, India. Records of the Geological Survey of India, Jaipur (113) part (7), pp Ghose B., Kar A. and Hussain, Z. (1979). The lost courses of the Sarasvati river in the Great Indian desert: New Evidence from the Landsat imagery. The Geographical Jour., London, V. 145 (3), pp Ghose B., Kar, A. and Hussain Z. (1978). Comparative role of the Aravalli and the Himalayan river systems in the fluvial sedimentation of the Rajasthan desert. Paper presented at the Map India

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