Inventory of Rapid Reconnaissance Soil Survey for Prioritisation Of

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Inventory of Rapid Reconnaissance Soil Survey for Prioritisation of Micro-watersheds of 3C2C1,4-6 Watersheds of Brahmaputra Basin Districts Cachar and Hailakandi districts of Assam, and Imphal East and Churachandpur district of Manipur using Remote Sensing and GIS Techniques

ABSTRACT

1. Survey Area : Cachar and Hailakandi districts of Assam, and Imphal East and Churachandpur district of Manipur

2. Geographical Extent : 24 13′ to 24 54′ N Latitudes and 92 38′ to 93 10′ E Longitudes

3. Agro Climatic Region : Eastern Himalayan Region II (as per planning commission 1989)

4. Total area of the district : 202963 ha.

5. Type of Survey : Rapid Reconnaissance Survey using Remote Sensing & GIS Techniques

6. Base map : a) IRS – ID Geocoded Satellite Imagery (1: 50,000 scale) b) SOI –toposheet (1:50,000 scale)

7. Scale of Mapping : 1 : 50000

8. Period of Survey : Nov to Dec,2010

A. Areal Extent of different Runoff Potential Mapping Units Runoff Potential Area Sl.No. RPMU (%) Value ( ha.) 1 AC01 56 3592 1.77 2 AC02 59 223 0.11 3 AC03 60 4413 2.17 4 AC04 67 572 0.28 5 AL01 58 232 0.11 6 AL02 63 421 0.21 7 AL03 54 7189 3.54 8 AL04 57 10254 5.05 9 AL05 58 268 0.13 10 AL06 56 19614 9.66 11 AL07 56 2209 1.09 12 AL08 56 98 0.05 13 AL09 56 139 0.07 14 AL10 58 1904 0.94 15 AL11 61 1127 0.56 16 AL12 56 9788 4.82 17 AL13 56 2657 1.31 18 AL14 64 405 0.20 19 AL15 57 2103 1.04 23 AL19 59 111 0.05 24 SD01 75 517 0.25 25 SD02 71 2611 1.29 26 SD03 66 1849 0.91 28 SD05 91 11128 5.48 29 SD06 82 7880 3.88 30 SD07 76 8063 3.97 31 SD08 86 3108 1.53 32 SD09 84 6579 3.24 33 SD10 70 8670 4.27 34 SD11 66 472 0.23 35 SD12 83 3960 1.95 36 SD13 76 2796 1.38 37 SD14 65 8673 4.27 38 SD15 62 1059 0.52 39 SD16 63 5013 2.47 40 SD17 75 23272 11.47 41 SD18 66 16997 8.37 42 SD19 60 6673 3.29 44 SD21 68 624 0.31 46 SD23 81 3465 1.71 47 HOMESTEAD 0 6912 3.41 48 RIVER 0 2281 1.12 49 WATERBODY 0 3042 1.50 Grand Total 202963 100

ii Hydrological Divisions Water Resource Region (3) Basin (3C) Catchment (3C) Subcatchment (3C2C) Watersheds (3C2C 1, 4, …..) Subwatersheds (3C2C 1a,.b, .c...... ,) Microwatersheds (3C2C1a1..., 3C2C 4a1, ...)

B. Area Under Different soil erosion Classes Assam Manipur Area Area Erosion Classes Hailakandi Cachar Churachandpur Imphal East (ha) (%) None to slight erosion 555 46324 144 2270 49293 24.29 Slight to Moderate erosion 137 12171 49 2421 14778 7.28 Moderate erosion 613 23304 3271 3893 31081 15.31 Moderate to Severe erosion 635 25693 9012 2800 38140 18.79 Severe erosion 548 40793 6282 9813 57436 28.3 Misc. 227 10837 578 593 12235 6.03 Total 2715 159122 19336 21790 202963 100 C. Distribution of area (ha.) under different slope classes Assam Manipur Area Slope Classes Hailakandi Cachar Churachandpur Imphal East (ha) % Plain to nearly level slope 72 3935 139 4146 2.04 Nearly level to Very gentle slope 293 34189 289 34771 17.13 Very gentle slope 1757 23 1780 0.88 Very gentle to Gentle slope 230 18152 144 3111 21637 10.66 Gentle to Moderate slope 97 6516 1232 2117 9962 4.91 Moderate to strong slope 1395 42903 3693 4588 52579 25.91 Strong to steep slope 10757 907 4824 16488 8.12 Moderately steep to steep slope 14690 4876 2728 22294 10.98 Very steep to Very very steep slope 401 15386 7906 3378 27071 13.34 Miscellaneous 227 10837 578 593 12235 6.03 Total 2715 159122 19336 21790 202963 100.00

iii D. Distribution of area (ha.) under different depth classes Assam Manipur Area Depth Classes Hailakandi Cachar Churachandpur Imphal East (ha) % Shallow to Moderately deep 6183 212 1190 7585 3.74 Moderately deep to deep 767 31821 4863 5484 42935 21.15 Deep to very deep 1126 52255 13539 11177 78097 38.48 Very deep 595 58026 144 3346 62111 30.6 Misc. 227 10837 578 593 12235 6.03 Total 2715 159122 19336 21790 202963 100

E. Distribution of area (ha.) under different land use classes Assam Manipur Land Use Imphal Area Classes Hailakandi Cachar Churachandpur East (ha) % Agriculture lands 390 44783 2989 6254 54416 26.81 Forest lands 1770 71695 15728 12915 102108 50.31 Plantation 256 21129 1071 22456 11.06 Open Scrub 673 673 0.33 Waste Land 6070 41 957 7068 3.48 Miscellaneous 299 14772 578 593 16242 8.00 Total 2715 159122 19336 21790 202963 100.00

F. Area under different Priority Categories No. of Area Sl. No. % Priority Category Microwatersheds (ha.) 1 Very High (above 70) 107 71219 35.09 2 High (66-70) 61 37786 18.62 3 Medium (61-65) 62 39084 19.26 4 Low (56-60) 98 54555 26.88 5 Very Low (55 & below) 4 319 0.16 Grand Total 332 202963 100

G.Watershedwise distribution of Area (ha.) under different Priority Categories Area Watershed Very High High Medium Low Very Low (ha) 3C2C1 18018 8965 4525 19066 50574 3C2C4 3000 12504 18778 25898 314 60494 3C2C5 6290 7402 9955 7415 31062 3C2C6 43911 8915 5826 2176 5 60833 Total 71219 37786 39084 54555 319 202963

iv H. Districtwise distribution of area (ha.) Microwatershed under different Priority Categories Assam Manipur Imphal Area Priority Category Hailakandi Cachar Churachandpur East (ha) % Very High (above 70) 371 42915 16057 11876 71219 35.09 High (66-70) 1210 30360 2665 3551 37786 18.62 Medium (61-65) 596 33682 609 4197 39084 19.26 Low (56-60) 538 51851 2166 54555 26.88 Very Low (55 & below) 314 5 319 0.16 Total 2715 159122 19336 21790 202963 100.00

Salient Features:

 3C2C1, 4-6 watershed has been subdivided into 332 microwatersheds following the delineation and codification method outlined in Watershed Atlas of India (1:1 M scale), 2012.  71219 ha of land (i.e. 35.09 % of the whole area) covered by 107microwatersheds comes under very high priority area and 37786ha (18.62%) area covered by 80 microwatersheds under high Priority that needs immediate attention for soil-water conservation treatment in order to check the soil detachment in the upper sub-catchment area and to control the devastating flood in lower sub-catchment for overall development of the area. 3C2C6, 3C2C1, 3C2C5 and 3C2C4 watersheds are the worst affected by runoff as well as flooding as compared to other watersheds which needs immediate attention to check the runoff from upper catchment and immediate measure for flood control under Integrated Watershed Management Programme.  About 40940 ha (20.17%) area of the survey area is unmanaged, and 236527ha. (11.65%) area is poorly managed. Severely eroded lands occupy 57436ha. (28.3%) while moderately to severely eroded land cover 38140ha (18.79%) and moderate eroded land 31081 (15.31%) that also needs proper soil-water conservation practices under Integrated Watershed Development Planning.

HOW TO USE SOIL SURVEY REPORT This report on Prioritisation of Micro-watersheds of 3C2C1, 4-6 Watersheds of Brahmaputra Basin Cachar and Hailakandi districts of Assam, Imphal East and Churachanpur districts of Manipur using Remote Sensing and GIS Techniques aims at identifying the microwatersheds which are relatively more prone to flooding and seasonal water logging and need the flood control measures. Further, it furnishes information on general characteristics of the catchments with particular reference to their location and extent, physiography, relief and drainage, geology, climate, land use and soils of the area also.

The subcatchment is delineated and codified following the codification system of Watershed Atlas of India (WAI) published by Soil & Land Use Survey of India in September, 1990. The surveyed area comprises 4 watersheds 3C2C1,4-6 of WAI which are subdivided into 55 subwatersheds and finally into 332 microwatersheds. Subwatersheds are codified by suffixing small case English alphabets with the watershed code e.g. 3C2C1a, 3C2C1b etc and microwatersheds are codified by affixing Arabic numerical with the subwatershed code, e.g., 3C2C1a1, 3C2C1b1 etc. Within a microwatershed, Runoff Potential Mapping Units (RPMUs) are demarcated and symbolized with alphanumeric codes viz. AL01, AL02, AC01, AC02, GN01, GN02 etc. The Runoff Potential Mapping Units (RPMU) is established by visual interpretation of False Color Composites (FCC) of IRS-P6 LISS-III followed by field verification. The RPMUs represent the landscape, physiography, slope, soil characteristics, existing soil conservation status, land use and severity of erosion of each mapping unit. These Runoff Potential mapping units are described in the Table 5 on ‘Legend to Runoff Potential Mapping Units’. Each of these units is assigned its runoff potential (RP) value which indicates the potential runoff from the microwatershed. Differentiating morphological characteristics of the Run-off Potential Mapping Units have been depicted in the Table 6

Based on Run-off Potential (RP) value and the extent of RPMU in a microwatrshed, the Runoff Potential Index (RPI) values of all microwatersheds are computed which is given in the ANNEXURE-I. The relative priorities are assigned based upon the Runoff Potential Index (RPI) of the microwatersheds. Higher the value of Runoff Potential Index (RPI) indicates higher priority whereas the lower value indicates lower priority. The list of microwatersheds under different priority categories are given in ANNEXURE-II.

Microwatersheds categorized under very high and high priority are to be selected for management of flood prone area under FPR Scheme. Both treatable and non-treatable lands are occupied by each priority (very high or high category) microwatershed. The ratio of treatable and non-treatable lands in a priority microwatershed varies with the kind, degree and extent of the degraded lands occupied by the same microwatershed.

Each map sheets on 1:50,000 scale depicting the drainage network, hydrological units, runoff potential mapping units and administrative boundaries are appended with this report.

For any further clarification, information or comments contact may be made to: Chief Soil Survey Officer Soil Survey Officer Soil and Land Use Survey of India Soil and Land Use Survey of India I.A.R.I. Buildings, New Delhi 110012 Or E-Block, B. P. Township, Telefax-011-25843811 Kolkata-700094 E-mail:[email protected] Telefax-033-24301425 E-mail: [email protected] Website: http://slusi.dacnet.nic.in

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