[ VOLUME 5 I ISSUE 4 I OCT.– DEC. 2018] E ISSN 2348 –1269, PRINT ISSN 2349-5138 RIVER FLOOD: A STUDY OF -II BLOCK OF KOCH BIHAR DISTRICT,,

Prasanya Sarkar* & Rajib Mitra** *Guest Teacher, College, Coochbehar, West Bengal, India . **Research Scholar, Department of Geography and Applied Geography, University of .

Received: July 26, 2018 Accepted: October 05, 2018

ABSTRACT Flood is a natural hazard which has an adverse effect on normal life of the people. The Koch Bihar district in West Bengal is susceptible to river floods due to its topography, rainfall characteristics, nature of rivers, anthropogenic activities, etc. For our present study we have selected the Tufanganj-II block to identify the riverineflood prone areas. The work has been done by analysed and interpreted the secondary data using remote sensing and GIS techniques.The study reflects that out of 55 villages 22 villages are most vulnerable due to river flood. The causes behind the flood havoc and government strategies to remove the flood hazard in this block also mentioned throughout the work.

Keywords: Flood, Tufanganj-II block, Vulnerable Villages, flood management.

Introduction Flood is a stage of high water level, which inundatesthe low lying area of the adjacent flood plains. In any reach ofthe river system floodshave direct relationship with the catchment characteristics of its upstream area (Smith et al, 1998).Basically flood is a natural feature of the rivers which replenishes the floodplain areas and convertsit into fertile land. But sometimes it becomes disastrous when associated with high discharge, heavy rainfall, etc. In Koch Bihar district, Tufanganj-II block is affected by riverine floodsalmost every year. Raidak-I, Raidak-II and Sankosh Rivers are the major rivers which caused flood havoc in this block. Both structural and non-structural measures have been taken to check the problem of floods. Initial emphasis was given only on structural measures like embankments, reservoirs and improvement of drainage channel. But now focus have been shifted to non-structural measureslike flood forecasting, flood plain zoning, etc. Application of GIS and modern remote sensing technology make it easier to map flood prone areas of Tufanganj Block II, identify the most vulnerable and vulnerable areas on the basis of flood recurrence. It will help the government to plan different strategies to cope with flood problems in the study area and also the people to save their lives and properties from the damages of a flood. The present study aims to give an account of flood prone areas of Tufanganj II block along with assessment of the causes behind the flood havoc and present day picture of different strategies taken by government to fight against the flood situation in this block.

Data base and methodology The secondary data is used in the paper which have been collected from the Disaster Management Plan, Koch Bihar for the year 2016. For the present study, the relevant maps have beenpreparedin ArcGIS 10.2software using satellite imagery.In the study, Landsat images have been obtained from the Earth Explorer gateway of United Nations Geological Survey (USGS). To analyse the existing status of the water cover NDWI map has been prepared.The normalized difference water indexes (NDWIs), calculated from various band combinations ((green, near-infrared (NIR), or shortwave-infrared (SWIR)), have been successfully applied to land surface water (LSW) mapping.The formula is used for calculating NDWI is: NDWI= (GREEN -NIR)/ (GREEN+NIR)

Characteristics of the study area Koch Bihar district is located at the foothills of the eastern Himalaya and in this region after heavy rainfall the catchment of the rivers attain strong current and flooded in the adjacent areas. The river of Koch Bihar district flow from north-west to south-east direction. Mainly six major rivers flow throughout the district,namely, Tista, Jaldhaka,Torsa,Kaljani, Raidak and Gadadhar.Flood is almost a yearly phenomenon in Koch Bihar district.Here some recorded data of flood occurrences of the district are given (table. 1). Tufanganj II is an administrative division of Tufanganj subdivision of Koch Bihar district in West Bengal. This block has an area of 257.08 sq.km. The turbulent rivers carry pebbles, sand and silts in and around the block. The soil is formed mainly by the alluvial deposits and slightly acidic in nature. It is friable loam to

514헎 IJRAR- International Journal of Research and Analytical Reviews Research Paper [VOLUME 5 I ISSUE 4 I OCT. – DEC. 2018] e ISSN 2348 –1269, Print ISSN 2349-5138 http://ijrar.com/ Cosmos Impact Factor 4.236 sandy loam ranging in depth from 0.15 to 1 metre. The soil has a low level of nitrogen, deficiency of zinc, calcium, magnesium and sulphur are also found here. The block is litho-stratigraphically composed of Holocene deposits.As per 2011census, the block comprises a total population of 1, 86,726 out of which 1, 16,081 people are affected by flood. Gram Panchayats of Tufanganj IIblock areBarokodali I & II, Bhanukumari I & II, Falimari, Mahishkuchi I & II, Rampur I & II and Salbari I& II. Among 141 gram sangsads, 45 villages are most vulnerable and 31 are in vulnerable conditions.

Fig. 1

Fig.2: Rainfall characteristics of the Tufanganj-II block (2013-2015); Source: Disaster Management Plan, Koch Bihar, 2016 and complied by the researchers.

Research Paper IJRAR- International Journal of Research and Analytical Reviews 515헎 [ VOLUME 5 I ISSUE 4 I OCT.– DEC. 2018] E ISSN 2348 –1269, PRINT ISSN 2349-5138 Table 1: Occurrence of flood in Koch Bihar district(2004-2014) Date of Affected areas No. of affected villages Affected River occurrence and blocks people 12th July, , Santoshpur, 341 villages and 2 69,968 Raidak I, Mansai, 2004 Tufanganj I, Arampur spur I , Kaljani and Balarampur Gadhadhar 28 th July, Mathabhanga, Kedarhat and 113 villages 25000 Torsa, Mansai and 2007 Jorshimuli Sankosh 22nd July, Tufanganj, Mathabhanga Ghaonapara, - Raidak II, Mujnai 2008 Mahiskuchi and Torsa 27th August, Koch Bihar Sadar and Wards 1,2,3,6,7,10 and Torsa and Teesta 2008 11 2000 17th August, 25-Teesta Payosthi, 40- Mekhliganj 337 Teesta , Torsa 2009 Payosthi, 72-Nijtaraf, families and Paniyachar at Mekhliganj 17th June, Tufanganj, and Koch Tufanganj I & II, Sankosh, Raidak, 2012 Bihar Dinhata I & II, Koch Kaljani, Torsa and Bihar I & II 40000 Mansai 17th July, Mekhliganj, Mathabhanga and Koch Bihar I & II, 50000 Teesta, Torsa, 2012 Koch Bihar Town Mathabhanga I& II and Jaldhaka, Kaljani Mekhliganj and Sankosh 28th August, Villages of Natabari, Tufanganj I& II, Koch 25000 Kaljani 2014 Chilakhana, Bhuchumari Bihar I & II Source: Disaster Management Plan, Koch Bihar, 2016 and complied by the researchers.

Results and Discussion The water bodies have a unique spectral response in the visible range when compared tothe surrounding land cover. Each of the visible bands, displays a unimodel histogram withno indication of a separate group of data for water pixel. The infrared band classificationgives a much better representation in the water related features than do the other visiblebands. This property makes the water pixel well identifiable, appearing blue to dark blue infalse colour composite. Water extraction image, NDWI (satellite imagery 6th April 2014) processed for delineating the area. Remote sensing has more advantages than the traditional methods of land surface water (LSW) mapping because it is a low-cost, reliable information source that is capable of making high-frequency and repeatable observations. Here the NDWI map of the study area showed to glean out the wetness condition of the area demarcated from grey to black tone combination whereas the blue tone is the signature of land surface (Fig. 3).

Fig. 3: NDWI maps of the study area 516헎 IJRAR- International Journal of Research and Analytical Reviews Research Paper [VOLUME 5 I ISSUE 4 I OCT. – DEC. 2018] e ISSN 2348 –1269, Print ISSN 2349-5138 http://ijrar.com/ Cosmos Impact Factor 4.236 Raidak-I, Raidak-II and Sankosh Rivers are the main rivers throughout the block and they inundate the riparian villages in every year. The villagers have been affected by floods in 2016 is 85793 (Table. 2). It has been observed that out of 55 villages 22 were most vulnerable due to river floods (Fig. 4). The most vulnerable villages are Bhandijilas, Langolgram, Begarkhata, Debgram, Dhanmatia, Saoerkuti, Manshai, Vanukumari, Chht Bara Laoukuti, Phalimari, Fersabari, Mahishkuchi, Paglirkuthi, Takua Mari, Chadbhalka, Rampur, Garbhanga, Jaldhao, Khagribari, Madhurbasa, Rampur-II, Singhimari and Shalbari. The villages are situated along the banks both left and right of the rivers. Table 2: Flood prone areas of Tufanganj II block Name of Name of the Flood prone No of persons to the river GP Mouza be affected 1. Falimari 2. Takulya Colony

3. Barnikata Raidak-II & 4. Khunipara Sankosh Falimari 5. Madhyachar 9376 6. Pora Colony 7. Chikantala 8. Bhubonerchar 9. Pachani Para 10. ChhatFalimara 11. PurbaFalimari 1. Ghonapara 500 2. Gedarchar 2212 3. Fersabari 546 Raidak-II & Mahishkuchi-I 4. Ghokso Part 645 Sankosh 5. Jaldhowa part 2020 6. Kathalguri 2500 7. Mahiskuchi part 4453 1. Takomari 2130 2. Paglirkuthi 765 3. Jaldhowa pat 657 Raidak-II & Mahishkuchi- 4. Rasikbeel 2145 Sankosh II 5. Bakla 1654 6. Atiamochar 546 7. Taterkuthi 654 1. Harirpur Part 1654 2. Bhandijelash part 1876 3. Langalgram 1235 Raidak-I Barokodali-I 4. Boalimohan 2 part 376

5. Jhingapuni 1134 6. Barokodali part Mechkoka 2236 1. Debagram 1654

2. Mansai 2534

Raidak-II Barokodali-II 3. Dhanmatia 1252 4. Sourkhata 3123 5. Begarkhata 1654 6. Boalimohan 150 1. Chhotolowkuthi 2745 2. ChhitBorolowkuthi 3354 Raidak-I Bhanukumari- 3. Bhanukumari Char 3425

Research Paper IJRAR- International Journal of Research and Analytical Reviews 517헎 [ VOLUME 5 I ISSUE 4 I OCT.– DEC. 2018] E ISSN 2348 –1269, PRINT ISSN 2349-5138 &Gnagadhar I 4. Bhanukumari Uttar &Purba 3575 1. Balakuthi Part 645 2. ChhatBhareya 657 Raidak-I Bhanukumari- 3. Nakarkhana Part 576 II 4. Ohaidabri Part 657 5. Shilghagri 987 6. JhowkuthiMantani 557 1. Banasraja 1st part 3235 2. Banasraja 2nd part 3000 Raidak-I Salbari-I 3. PaschimSalbari 567 4. Salbari 1325 5. ChengtimariDorko 2500 1. BaroSalbari 3210 Raidak-I Salbari-II 2. Birodhirpar 3198 3. Sajrapar 912 4. Turkanirkuthi 987 Total no. of people affected by floods 85793 Source: Disaster Management Plan, Koch Bihar, 2016 and complied by the researchers

Fig. 4

Flood in Tufanganj-II block are the responses of both natural and anthropogenic factors. Meteorological and physical factors cause a serious flood situation in this area. But presently the human activities accelerate the occurrence and dimension of flood in the study area.Heavy rainfall for a longer duration can cause flooding by increasing the volume of water in the river. The increased water overtops the riverbanks and inundates the adjacent areas. In Tufanganj-II block highest rainfall is found between June- September i.e. in the monsoonal months (Table. 3). Table 3: Rainfall of Tufanganj-II block (2008-2015) Month Rainfall ( in millimetre) 2008 2009 2010 2011 2012 2013 2014 2015 January 39 - - 3 3 - - 22 February 10 - - 11 11 18 18 57 March 76 36 30 56 3 4 10.0 10.3

518헎 IJRAR- International Journal of Research and Analytical Reviews Research Paper [VOLUME 5 I ISSUE 4 I OCT. – DEC. 2018] e ISSN 2348 –1269, Print ISSN 2349-5138 http://ijrar.com/ Cosmos Impact Factor 4.236 April 188 108 385 138 173 192 9.0 140

May 282 287 600 294 242 384 547 327

June 569 510 711 431 947 342 689 764 July 606 402 863 775 779 506 233 180

August 841 629 525 476 337 321 480 892

September 299 196 496 465 614 586 523 544

October 147 270 61 20 245 151 4 20 November - - 2 - - 8 - 7 December ------5 Source: District Disaster Management Plan, Koch Bihar, 2016 and complied by the researchers

The Raidak-I, Raidak-II, Sankosh and Gadadhar rivers have formed various meanders and mostly they follow sinuous way. These impede the natural discharge of the rivers and the velocity is reduced. So when the excess water of rainy season flow through this channel, there is a stagnation of water, and the meanders are immediately overflowing.Sankosh River has shifted its course several times in the study area, which cause inundation of the lowlying areas.Both natural and anthropogenic factors are responsible for siltation of river beds, which reduce the water retention capacity of a river by raising the bed level. As a result the rivers could not accommodate the huge amount of water during rainy season and flooded this block every year.Some dams are created by neighbouring country like Bhutan for hydroelectric power generation in the upstream part. Behind these dams huge amount of water is impounded. In the rainy season these dams become incapable to hold excess water, so Bhutan Government discharge water from these dams without giving any prior information, which causes flooding in the study area. There have been several measures, which are taken to protect the vulnerable areas from flood and also water level reduction during the flood peak. Constructing embankments are considered very effective measure against inundation in Tufanganj block-II. Armoured and non-armoured embankments, both Types of embankments are done here to safeguard the vulnerable mouzas. Table 4: Embankments and area under protection in the study area River Name of the structure Bank Embankments Bank Area Protection benefitted (in sq.km) 1. Begarkhata embankment L/B 120 M 0.40 2. Ghonapara B.P. R/B 350M 0.10 embankment 3. Banasraja village scheme R/B 450M 0.13 Raidak –I 4. HarirpurB.P.work L/B 600M 0.18 5. Dwiperpar B.P. work R/B 300M 0.09 6. DebagramRajarkuthi R/B 570M 0.18 7. Langalgrambegarkhata L/B 900M 0.27 1. Mahiskuchi embankment R/B 250M 7.50 Raidak-II 2. Jaldhowa Ghat L/B 300M 0.90 Embankment Source: District Disaster Management Plan, Koch Bihar, 2016 and complied by the researchers In Tufanganj –II block several rescue centres have been formed to give shelter to the flood affected people. Table 5: Name of the Flood Shelters in Tufanganj-II block Name of the GP with Name of the Present capacity Area to be village/Location flood shelter status covered Falimari Falimari GP school usable 600 Falimari Rampur-I NaziranDeotikahta pry. School usable 600 NaziranDeotikhata, ChhatBhalka

Research Paper IJRAR- International Journal of Research and Analytical Reviews 519헎 [ VOLUME 5 I ISSUE 4 I OCT.– DEC. 2018] E ISSN 2348 –1269, PRINT ISSN 2349-5138 Rampur-II Dakdhin Rampur no.2 Pry usable 600 Rampur School Gharbhanga Rampur-II Jaldhoa no.2 Sc pry. school usable 600 Jaldhoa Rampur-II Rampur Girls High School usable 700 Rampur Singimari Mahishkuchi-I FershabariNetajiVidyapith usable 600 FersabariGhonapara Falimari PurbaFalimariPachanipara unusable 600 Falimari A.P, School Mahishkuchi-II Takoamari Govt. Pry. School usable 600 TakoamariRasikbil Barokodali-I HarirpurRabindraVidyapith unusable 600 Harirpur Langolgram Barokodali-II Begarkhata AP School usable 600 Begarkhata Sourkhata Shalbari-I Banasraja partII kuthibari usable 600 Banasraja Pry. School Shalbari-II Bajrapur Pry. School usable 600 Bajrapur Bhanukumari-I Barolawkuthi Pry. School usable 600 Barolawkuthi Bhanukumari-I Boxirhat usable 800 Bhanukumari Chhatalowkuthi Bhanukumari-II Dhaldabri no.2 pry. school usable 600 Dhaldabri, Chhatbhaya Source:District Disaster Management Plan, Koch Bihar, 2016 and complied by the researchers Besides rescue centres other flood management plans have been drawn by the department of disaster management, Koch Bihar. These are-  No. of helipad ground identified: 3 (Falimari Nehru Vidyapith Ground, Jorai Play Ground, Mahishkuchi High School ground).  No of dry food dealers: 24.  No of boats identified: 31.

Conclusion In Tufanganj-II block flood is a natural hazard which occurs frequently. 22 villages are identified and have been declared as vulnerable villages. Although some structural measures like embankments, spurs have been done by the government to protect the block. But these strategies are expensive and time consuming. So the concentration should be shifted to non-structural measures like flood forecasting, flood plain zoning and flood plain regulation. Remote sensing and GIS database is ideally suited for these non-structural measures. By the continuous recording of meteorological data, frequency of flood and related data, flood forecasting should be done and also disseminate in the study area through electronic media, so that the people of the flood prone areas can be evacuated in the safe places in due time. There should be strict regulation on constructing houses or other activities on the flood plain by flood plain zoning. Although flood is a natural phenomena, so we can’t stop it, but applying remote sensing and GIS and also some structural measures we can reduce the adverse impact of flood in the study area.

Acknowledgements We acknowledge the US Geological Survey for free downloading the Landsat data and Koch Bihar Disaster Management Plan for providing the data related to the flood.

References 1. Annual Flood Report for the Year 2013, Government of West Bengal. 2. Chakraborty,S. and Dutta, K., 2013: Causes and Consequences of Fluvial Hazards- A Hydro-Geomorphic Analysis in Duars Region, India, Indian Stream Research Journal, Vol.2, Issue.12, pp. 1-10. 3. Choubey, V. K., 1997: Detection and delineation of waterlogging by remote sensing techniques, Journal of the Indian Society of Remote Sensing, 25(2), pp. 123-135. 4. District Disaster Management Plan, Koch Bihar, 2016. 5. Smith, K. and Ward, R., 1998: Floods, Physical Processes and Human Impacts, John Wiley and Sons Ltd., England, ISBN: 0 471 95248 6, pp. 61-79. 6. https://earthexplorer.usgs.gov.

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