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Assessment of the status of surface waterlogging in Sarda Sahayak Command area of Uttar Pradesh, India using IRS-1A, LISS-1 Data

P.N. Shah and A.C. Mathew
Remote Sensing applications centre, U.P.
Sector-G, Jankipuram, Kursi road,
Lucknow-226007, India


Abstract
The Sarda Sahayak Command area lies between the Ghaghra and the Ganga rivers in Uttar Pradesh extending upto their confluence. Since the commissioning of canal system in 1976, the groundwater regiment in the canal command has led to a general rise in groundwater table. At some places it has resulted in surface waterlogging and increase of areas of salinity. An attempt has, therefore, been made to understand the impact of seepage from the Sarda Sahayak canal system with special reference tot eh land degradation using IRS-1A, Liss-1 satellite data of February 1989. About 200 ground observation points were selected in the field for measurement of standing water above round. These points were accurately located on the 1:50,000 image analysis. Maximum likelihood supervised classification algorithms was used for classifying various categories of aquatic vegetation in the categorized waterlogged areas and in assessing the surrounding landuse features. The surface water depth classification has shown that it is possible to discriminate the different levels of standing water within waterlogged areas viz., (i) water less than 15cm., (ii) water more than 15cm and less than 75cm, and (iii) water more than 75 cm. the computer classified IRS-1A, Liss-1 satellite data after integration of groundtruth has shown that 15.19% of the area has become surface waterlogged and rendered infertile for the winter crops (Rabi).

Introduction
The Sarda Sahayak feeder channel is a major canal system in the state of Uttar Pradesh commissioned in 1976 to supplement water supplies in the lower reaches. The command of the canal system covers 14 districts of central and eastern part of Uttar Pradesh. A feeder channel taking off on the right bank of Sarda barrage has a designed capacity discharge of 650 cumecs at the head and supplies water to Dariyabad, Barabanki, Haidergarh, Sultanpur, Jaunpur, Azamgarh, Pratapgarh, Raebareli, Allahabad, Shahganj and Marihau branches and their distributaries. The seepage along the feeder channel and in their distributaries. The seepage along the feeder channel and in the command has brought in its wake the attendant problems of water logging and increase in soil salinity. These land degradation processes have further adversely affected the efficient utilization of the land resources in the command. The groundwater regimen has also undergone changes and a general rise in the ground water table has been observed and in certain areas it has risen to the surface during the years of operation of the canal system. The resultant damage to the ecosystem is severe.

IRS-1A, Liss-I data of February, 1989 covering the entire Sarda Sahayak command have been digitally analysed after integrating the real time groundtruth to generate real time information on the status of waterlogging. The maximum likelihood supervised classification algorithms was used for accurate and the quick assessment of surface waterlogging in the canal command area and can be operationally utilized for dynamic assessment of environmental of impact of the large scale canal system.

Objectives

The main objectives of the study were :
  1. to study land degradation as a result of surface waterlogging and salinity

  2. to assess the extent of surface waterlogging and discriminate the aquatic vegetation in waterlogged areas of command.

  3. to develop methodology to identify different levels of standing water above the surface in the water logged lands.

  4. to delineate level-I landuse pattern in the command.

  5. to detect changes I the status of waterlogging in space and time.
The area
The Sarda Sahayak command area lies between the Ghaghra and the Ganga rivers extending upto their confluence i.e. between 8000" E & 84075'E longitude and 25019'Nlatitude . The command area covers over 161 development blocks of 14 districts of Uttar Pradesh. Physiographically, the area is almost a flat terrain with occasional undulations. The general slope of the terrain is Northwest to Southeast. Geologically, the area comprises alluvium and forms a part of the Ind-Gangetic alluvial plains. geomorphologically, the area can be divided into the highland comprising older alluvial and lowland marked by marked by younger alluvium: Te Ghaghra, Sarda, Gomti, Sai, Chauka, Reth, Rari, Kalyani, Bethwa, Naiya, Somli, Varuna etc., rivers draining the command area have changed their river course form time to time and left behind old meanders, ox-how lakes, paleochannles, depressions etc., which are periodically inundated causing extensive waterlogging. The soils in the area are derived from the alluvium and are clayey loam to silty clay containing pockets of scandy loams. The soils at many places has become saline which are locally called as 'Usar'. In general, the groundwater table varies fro0.5m to 2.0m below ground level in the vicinity of canal system.

Data inputs
The black and white aerial photographs on :15,000 scale and Landsat MSS/TM data were visually interpreted prior to the field checking for selecting suitable training sets. The survey of India topographical maps in 1:50,000 scale were utilized for locating training area. IRS-1A, Liss-I satellite scenes (FCC/CCT's of P24-R49, P25-R49, P26-R48) of February 1989 covering the entire part of the command area used for the visual and digital image analysis. Covering the surface waterlogged area adjacent to the feeder channel from head to ch. 104.2 km was also used for change detection study (Report No. RSAC:WD:85"01"1985).


Fig.I Location map of Sarda Command area


Approach and methodology
The methodology adopted for the assessment of surface water logged areas in the command is show in fig. II. It broadly involves the following five steps :
  1. Pre-field interpretation of aerial photographs and satellite data & collection of collateral information.

  2. Near real time ground truth collection & selection of training sets.

  3. Visual interpretation of IRS-IA, Liss-I data.

  4. Digital image analysis of IRS-IA, Liss-1 Data

  5. Evaluation of results and report preparation

Fig.II Methodology for assessment of surface waterlogging
in Sarda Sahayak Command area


Results and discussions
The Sarda Sahayak system has led to excessive seepage of water which has led to extensive waterlogging and resultant increase of soil salinity in the command. During field checking, surface water logged areas were observed mainly along the feeder channel from head to ch. 160km and also on both sides of Dariyabad branch from 0 to 50km. Some areas in the downstream reaches of the command also showed surface water logging. About 200 ground observation points were accordingly selected in the field and the depths of standing water. KCB Raju et. al. (1985) had identified water logged and sanility areas in parts of the Nagarjuna Sagar Canal command using Landsat data. The water logged areas are characterized by the prevalence of high soil moisture areas, Standing shallow surface water areas and presence of perennial vegetation.

The maximum likelihood supervised classification algorithms for both general and depth classifications were used during digital image analysis of IRS-IA, Liss-1 data. The draining sets located on survey of India's toposheets on the basis of ground observations, were integrated with the IRS-IA and Liss-1 data through an interactive Pericolor (PC-2001) terminal of the image processing system configured around VAX 11/780 for both the classifications. The spectral signature keys for the classifications were developed on the basis of their tonal characteristics. The classification statistics and confusion matrix of each class were evaluated and the classifications have been found most useful in different various categories of aquatic vegetation in waterlogged areas and surrounding level-I, landuse classes. The classified outputs were geometrically rectified and stored in PCT using fire-format algorithms. The estimated of areas of the different categories of surface water logged land were computed. The first five categories shown in table 1 correspond to the different status of water logging and the remaining refer to the major land use classes. The digital computation shows that a total of 9595.04 sq km land in the entire Sarda Sahayak command are of 56,332.76 sq. km was surface water logged in February 1989. It has also been possible to digitally enhance and discriminate the different levels of standing water in the immediate vicinity of feeder channel between ch 40km & ch. 104.2 km. The areas of different levels of standing water were computed within the waterlogged lands and are given as under :
  1. Standing surface water upto 15 cm depth extends over 438.11 sq. km

  2. Standing surface water between 15 cm to 75 cm depth extends over 168.56 sq. km

  3. Standing surface water more than 75cm depth extends over 44.9 sq km.
Additionally, band rationing of bands 1 and 4 and Principal component analysis algorithms were also carried out enhancing the surface waterlogged features.

A comparative study of Landsat MSS classified data of December 1983 IRS-IA, Liss-1 data of February 1989 has been made for change detection in the surface water logged lands. It has been found that some areas to the east of left bank of feeder channels i.e. north of Sarda River and south of Ganghra river upto their confluence and also the area lying to the area south of Sarda river have shown improvement in the status of water logging during the last six years period. however, the areas lying to the west of Laharpur and north of Lucknow show a marginal increase it extend of salt affected lands compared to the status of 1983.

Table 1: Area estimation of surface waterlogged lands and landuse
calsses in Sarda Sahayak Command area using supervised
classification algorithms
Class No. Class Name Number of
Pixels		 Area in
Sq km		 Percentage
%
1. Moist soil 683622 3583.1276 6.380
2. Water with stubble of paddy 642249 3369.2661 5.992
3. Water with grass 238094 1249.0434 2.221
4. Water with weeds 59204 310.6177 0.552
5. Clear water 15783 82.960 0.147
6. Saline land 567278 2676.499 5.293
7. Sand 45905 240.7213 0.430
8. Ravine land 724712 3792.4362 6.762
9. Cropland 4334501 22718.162 40.444
10. Forest land 78584 412.3573 0.733
11. Pond/reservoir 24658 129.1094 0.230
12. River 39547 207.4066 0.369
13. Canal 68288 358.198 0.637
14. Unclassified 3194866 23052.197 29.810
Total 10717291 56332.762 100.000

Conclusion
The computer processed classified and enhanced IRS, Liss-1 satellite data integrated with ground truth inputs has given accurate and timely results for assessing the surface water logged lands in the Sarda Sahayak command area using supervised classification. The different categories of aquatic vegetation biz., water with stubble of paddy, water with grass, and water with weeds were digitally discriminated with the water logged ranging fro high soil moisture through 5 cm to more than 150 cm were also identified within the water logged lands along the feeder channel between ch. 40 km. & ch. 104.2 km length. It has also been possible to detect changes in the status of water logging along the feeder channel section between head and 104.2 km stretch. It is noted that some areas have been relieved from acute surface water logging as a result of measures taken up by the state irrigation department during the last six years.

Acknowledgement
The authors are grateful to Director, Remote Sensing applications Centre, Uttar Pradesh, Lucknow for permission to submit the paper to the 10th Asian conference on Remote Sensing.

Reference
  • Anon., (1984) Waterlogging and its remedial measures in Sarda Sahayak Command Area: A report of working group., October 1984.
  • Anon., (1985) An assessment of surface water logged areas in a part of Sarda Sahayak canal system covering parts of Lakhimpur and Sitapur District, Uttar Pradesh: A report by Remote Sensing Applications Centre, Uttar Pradesh.
  • K.C.B. Raju et. al (1985) Application of Remote Sensing techniques in the study of water logging in parts of the Nagarjuna Sagar Canal Command Area: proc. Of VIth Asian conference on Remote Sensing, Nov. 21-26, 1985 Hyderabad.
  • Usha Chatrath, (1983) problems in water resources, assessment, development and management in Sarda Sahayak command area development project: Proc. Of Sym. On Remote Sensing in development & Management of water resources, at Ahemdabad, October 25-27 1983.