Flood Mitigation through Integrated River Basin ...

Research Forum: International Journal of Social Sciences; ISSN: 2348 4411 (Volume-2, Issue-1) ISSN: 2347-9272 (Volume-1, Issue-1)

Research Article February 2014

Flood Mitigation through Integrated River Basin Management in Lower Brahmaputra River Basin, Assam Abhay Shankar Prasad Department of Geography, Delhi School of Economics, University of Delhi, Delhi-110007, India Abstract

The

term integrated river basin management refers to various essential attributes to achieve a sustainable

development in a riverine ecosystem and protect from flood. It is the process of coordination, conservation, management and development of water, land and related resources within a given river basin. It is essential to establish balance between the existing natural functions of the river system and the developed aspect of the system. It has been experienced that flood occurs almost every year in one or other part of the lower Brahmaputra river basin, Assam with varying frequency and magnitude. It is estimated that nearly 3.2 million hectares of land in the plains of Assam state are vulnerable to topsoil erosion with varying intensity of flood. During the monsoon season (JuneOctober), floods are a common occurrence in Assam. However, the year 2012 is said to be the worst in this decade. The important factors causing floods in Assam are heavy rainfall, inadequate capacity of river, severe soil erosion, river bed silting, landslides, earthquakes, river capture, poor drainage, deforestation, and practice of shifting cultivation or Jhoom as well as physical and anthropogenic causes. This paper mainly focuses on the managing floods through specific structural measures such as reservoirs, embankments, channel improvement, town protection, river turning works, watershed management, inter-basin transfer, bank protection and anti-erosion work. Nonstructural methods to control the floods and soil erosion should be through flood forecasting, flood plain zoning, changing cropping pattern and public participation in management works. Flood management is more effective than flood control. Keywords: Integrated River Basin Management, Land Use Pattern, Livelihood, Flood Mitigation, Sustainable Development. I. INTRODUCTION Integrated river basin management (IRBM) is understood to mean co-ordinate planning, development, agriculture and livelihood management and use of land, water and related natural resources within hydrologic boundaries, in order to maximize the resultant economic and social welfare in an equitable manner without compromising the sustainability of vital ecosystems. The term integrated river basin management refers to various essential attributes to achieve a sustainable development in a riverine ecosystem. Assam's Brahmaputra river basin represents one of the most acutely hazard-prone regions in the country, having a total flood prone area of 3.2 million hectare. The lower Brahmaputra basin, Assam has caused the hazards of annual floods and erosion, bringing misery to the people and shattering the fragile agro-economic base of the region. The region of lower Brahmaputra river faces a number of problems including occasional floods during monsoon, scarcity of water during lean seasons, huge sediment load and pollution. This thesis mainly focuses on assessment of vulnerability and identification of vulnerable issues of lower Brahmaputra basin with respect to various magnitude levels It is estimated that nearly 3.2 million hectares of land in the plains of Assam state are vulnerable to topsoil erosion with varying intensity of flood. During the monsoon season (June-October), floods are a common occurrence in Assam. However, the year 2012 is said to be the worst in this decade. The important factors causing floods in Assam are heavy rainfall, inadequate capacity of river, severe soil erosion, river bed silting, landslides, earthquakes, river capture, poor drainage, deforestation and practice of shifting cultivation or Jhoom as well as physical and anthropogenic causes. This paper mainly focuses on the managing floods through specific structural measures such as reservoirs, embankments, channel improvement, town protection, river turning works, watershed management, inter-basin transfer, bank protection and anti-erosion work. Non-structural methods to control the floods and soil erosion should be through flood forecasting, flood plain zoning, changing cropping pattern and public participation in management works . II. STUDY AREA The present study is carried in the lower Brahmaputra River Basin, Assam. It is located between latitudes of 24°08'N and 27°59‟N and eastern longitudes of 89°42'E and 96°01‟E (Figure1). Assam is the most populous state in the North-East India covering an area of 78,523 sq. km

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Fig 1: Study Area It is surrounded on three sides by hills and mountains with boundaries with Arunachal Pradesh, Nagaland, Manipur, Mizoram, Meghalaya, West Bengal, Bangladesh and Bhutan. The State of Assam consists of 27 districts for administration. The State can be divided into three distinctive geographic parts. The river Brahmaputra flows from east to west for about 700 km within the State and has great role in the land formation, hydrology, ecology, population distribution, culture and economy of the valley and the State. The Assam plain or lower Brahmaputra plain is one of the major geological territories of India. The Brahmaputra plain is also known as lower Brahmaputra Basin. The lower part of the Brahmaputra river valley is a devastatingly flood prone region with severe outcome to the economy, society and public health. During the monsoon season (June-October), floods are a common occurrence in Assam. Deforestation in the lower Brahmaputra river basin has resulted in increased siltation levels, flash floods and soil erosion in critical downstream habitat, such as the Kaziranga National Park in middle Assam. Occasionally, massive flooding causes huge loss to crops, life and property. The problem of flood in the plain of the lower Brahmaputra can be summarised as bank spilling, drainage congestion due to adverse outlet conditions and morphologic problems caused by heavy sediment load related to land use and seismic activities. The main problem facing the river basin is that of constant flooding. Floods have been occurring more often in recent years with deforestation and other human activities being the major causes. III. RESEARCH METHODOLOGY The present study titled “Flood mitigation through integrated river basin management of lower Brahmaputra basin, Assam” focuses on the extent and magnitude of flood and impact of flood on land use pattern in the lower Brahmaputra basin. For successful completion of the work with accuracy and clarity, an appropriate methodology has been used. It is based on both primary and secondary data collection. Secondary data has been used for various dimensions of the river basin issues as resource of the river basin, rainfall, deforestation, soil erosion, land use pattern etc. Primary data and information has been collected from relevant organisations during research trips to the study area. Secondary data has been collected from various governmental and local organisations from their published articles, books, documents and reports (Figure 2). To attain the useful data such as relief, drainage, geology, soil, climate, forests, surface condition, social and economic status has been collected from several institutions as District Agriculture Handbook; Brahmaputra project (Government of India), Soil Survey Report and Map, Field survey, Revenue Report, District Statistical Office etc. has given a base for the research work. Secondary data has been collected from Central Water Commission (CWC), which manages hydrometerological data collection, prepares flood forecasts, undertakes surveys, analyzes data and prepares detailed project reports.

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Research Methodology

Data collection

Data Processing

Primary Data

Data Representation

Secondary Data Map, Diagram, Charts

Table, Figure, Photograph Questionnaire

Interviews

Flood Effected Village, NGOs

Observation and Photograph

Government Offices

Brahmaputra Board‟s Employee

Fig. 2

Area in hectare

III. FLOOD CAUSES AND ITS MITIGATION THROUGH SUSTAINABLE DEVELOPMENT Land Use Pattern Assam is basically an agriculture dependent state. More than 65 per cent of its total area is under agriculture (Figure 3). The increasing pressure of population and the lack of employment opportunity in other sectors, the pressure on agricultural sector are increasing alarmingly. This situation leads to the intensification of agricultural sector and the fragmentation of land holdings. Such situation causes serious damage to the land and the economy of the state. 4500000 4000000 3500000 3000000 2500000 2000000 1500000 1000000 500000 0

Total area (in… Figure 3: Land use pattern in Assam, satellite base data, 2010 Source: Assam Remote Sensing Application Centre, Guwahati Agriculture is the dominant land use category in the Assam. It accounts for about 54.11 per cent of the total geographical area of the state and more than 80 per cent of the total population of Assam is dependent on agriculture. With the increase of population and the development of agro-technology, lots of changes take place in the agricultural scenario of the state. The net area sown as well as the gross cropped area increased significantly in the last few decades. This decreases the area under other uses especially area under forest. Although, the development in agriculture has tremendous importance in the economy of the state but the ecological impacts of the changing land use pattern need to be considered.

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The total areas under different type of wastelands in the Assam are about 13.5 per cent of the geographical area. The different types of wasteland seen in the districts are water logged area, swamps and marshes, gullied and ravinous land, land with or without scrub and the area under shifting cultivation (Figure 4). The degradation of forest in the upper catchments of the rivers enhance the problem of gully erosion, which already reach to unmanageable proportion in some area of the state. Thus an integrated wasteland development strategy is the need of the time. Shifting cultivation constituted the most dominant class accounting about 9.48 per cent state area. The large scale shifting cultivation is one of the main causes of forest degradation in the Karbi Analong and North Cachar hill.

Figure 4: Land use pattern, Assam, 2010 Source: Statistical Hand Book of Assam, 2010, Government of Assam Land use planning and flood mitigation It is assumed that crop diversification and change in land use pattern may help farmers to minimize risk arising from flood hazard. However, this has caused major changes in cropping patterns, use of agricultural inputs and management of soil erosion. Furthermore, the Assam devoted to high yield variety (HYV) rice cultivation which has helped increase the cropping intensity considerably. Use of inorganic fertilizers increased six times and the use of pesticides increased in Assam. The cropping pattern in study areas of 2008 contradicts with that of 2000 when compared with the riverbank areas in terms of less fallow land, less single cropping but more double cropping (Figure 5 and 6).

Figure 5: Fallow land area of Assam, 2010

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Figure 6: Double crop area of Assam, 2010 The practice of cultivating three crops in a year was identically higher in the riverbank areas during 2008. This gives the indication of higher adoption of modern agricultural technology in the study areas as well as possibly more profitability from agricultural practices/crop production. Both in the riverbank and study areas rice has been found to be the major crop, since the alternative crops like pulses, vegetables, potato, sugarcane, jute etc. are grown other than rice. The department of agriculture prepares a contingent crop planning to minimize the reduction in losses of production by way of selecting appropriate / alternate crop, suitable variety and by way of adopting appropriate production technology. The Assam Agriculture University organizes training on various aspects of agriculture in flood affected areas in its Krishi Vigyan Kendras (KVK) and Regional Research Stations. Net sown area and total sown more than one crop have increased and fallow land has decreased. It is helpful in adaptation from flood hazard events (Table 1). High Yield Variety (HYV) crop cultivation has more useful in mitigation of livelihood and helps to change in land use pattern in different way of planning to protect from flood hazard. The boro paddy that is grown most successfully is water resistant and grows in water logged and marshy areas and some varieties can withstand strong currents. The practice of mixing boro and ahu cultivation ensures that at least one crop survives in the case of early or high floods. Cultivation of boro paddy is a suitable alternative for Assam‟s flood area and more people are expected to plant it to ensure food security in Assam.

District Cachar Goalpara Kamrup Darrang Nagaon Sibsagar Lakhimpur Dibrugarh

Table 1: Land use pattern change due to flood for adaptation Area Sown more Net Sown Area Fallow land than one 1950-51 1975-76 2010-11 1950-51 1975-76 2010-11 1950-51 1975-76 2010-11 26.22 30.71 32.29 5.21 10.35 11.56 9.7 6.7 5.1 23.39 37.62 40.51 10.25 15.33 18.2 4.4 2.6 1.9 42.23 46 52.12 14.2 23.65 24.1 2.1 3.3 2.8 30.46 40.44 42.4 4.2 9.4 10.16 10.1 3.4 2.9 43.37 45.41 48.14 5.1 8.61 10.2 5.5 2.8 2.5 30.42 40.56 48.54 2.1 3.5 4.2 15.4 5.7 3.6 19.41 27.86 30.8 2 4.6 6.2 5.16 3.5 2.9 29.31 38.93 46.22 NA NA NA 7.26 3.86 3.2

Source: Statistical Handbook of Assam, 2011, Government of Assam The north-eastern region of India has remained economically backward due to their indiscriminate and mismanagement of land use. Socio-economic constraints viz. shifting cultivation, land tenure system, small size of land holdings, unabated deforestation, free range grazing and undulating terrain have affected the sediment yield and quantity and quality of available water (Sharma 1998, 2003). Shifting cultivation is practised in 3,869 km 2 areas, annually in NorthEastern region; however the total affected area is 14,660 km2. It has resulted in huge soil erosion in the hills and silting of river beds and floods in the plains. Deforestation in shifting cultivation has depleted the biodiversity of the region. The important issue is to promote the conservation and sustainable use of natural resources which allow long term economic growth and enhancement of productive capacity along with being equitable and environmentally acceptable (El Bassam,1997).

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The need for integration between land use and flood management plans has been recognized since long. Fundamental characteristics and the aims of those planning processes and policies have been driven and implemented by different stakeholders and decision-makers. Therefore, it is required to seek a mutual understanding by two processes of land use and flood management planning. The field of public policy that is referred to as “Land use Planning” has various corresponding terms which are sometimes used interchangeably. The urban areas in Assam are proliferating with haphazardly constructed and substandard buildings, non-engineered dwellings as well as uncontrolled land use (Figure 7). 10.00 Change in % of total geographical area

8.00 6.00 4.00 2.00

Change in Per cent

0.00 -2.00

Forest

Agriculture Settlement

Water bodies

-4.00 -6.00 Figure 7: Land use and land cover change, Assam 1975-2010

Source: Assam Remote Sensing Application Centre, Guwahati Urban vulnerability is largely a consequence of improper urban management, inadequate land use planning. The worsening vulnerability of urban areas is one of the primary reasons for rising disaster losses. The utility of land use planning in disaster risk reduction is still not so widely recognized much less taken advantage of by policy makers and local planners themselves and it is a high time to methodologically integrate risk reduction in land use planning. Reducing the risk of urban areas towards disaster is a systematic development and application of policies, strategies and practices to minimize vulnerabilities and risks throughout a society, to avoid or to limit adverse impacts of hazards, within the broad context of sustainable development. Integrated vulnerability assessment and land use planning procedure combines the assessment of hazards, vulnerability and risk with the standard planning process. It is only possible when vulnerability assessment procedure that seeks to reduce risks have a factual and scientific basis. In order to use planning tools and techniques for risk reduction, it is necessary to evaluate the factors contributing to those risks. Integrated land use planning incorporates hazard identification and evaluation (e.g. analysis of frequency, severity/magnitude, return period or probability of a hazard of seismicity of given severity), vulnerability analysis (e.g. loss of life, injury, building damage, economic impacts) and potential damage assessment (e.g. loss estimation), or collectively termed as vulnerability assessment. Applying land use planning techniques in vulnerability assessment and risk reduction includes a comprehensive analysis of the land use behaviour and translation of those risk assessment into location of land uses, functions, facilities and into land use regulations and policies. IV. CONCLUSION The theme of the research “flood mitigation through integrated river basin management” is subjects that integrates sustainable development and promote the integrated livelihood strategies of village community. The Brahmaputra basin in India, particularly its valley in Assam, represents an acutely flood prone region characterized by hazards of flood and erosion that creates an annual mayhem of devastation bringing untold miseries to the people and causing colossal loss and damage to public property and infrastructure. The total flood prone area in the Brahmaputra valley is estimated at 3.2 million hectares, which account for 9.6 per cent of the country‟s total area. Increasing population, rapid expansion of settlement and other human activities has been a major factor for the flood hazard in the year 2012. Most of the villagers are skilled swimmers and know how to use boats and rafts. The communities that face the floods year after year, in their own capacity have been implementing their traditional wisdom and early warning systems to reduce the risk during floods. Over the centuries, the mishing tribal group in Majuli and other parts of the upper stretch of the Brahmaputra has developed the elevated chang ghar, a bamboo house on stilts that can be dismantled or quickly restored after a flood surge. Housing plays a major role in protecting communities from floods in the study sites. The mishing community in Assam dwell on the flood plains and they live in traditional stilt houses called „chang ghar’. A type of house ideally suited to adapt to flood waters. A „chang ghar’ is usually a thatched house built on stilts made of wood and bamboo. The average height of the plinth is from six to eight feet above the ground, the height in general

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conforming to the highest flood level of the area adjudged from long-term observation and experience of past floods. The base of the house (floor) made of bamboo and wood is adjustable and can be raised to cope with rising flood waters. Flood mitigation strategies can be process in to long term and short term as structure and non-structure measurement. There are two different ways to mitigate floods: 1.

Structural (a) Embankments (b) Reservoirs (c) Natural water retention basins (d) Buildings on elevated area

2.

Non- Structural (a) Flood plain zoning b) Flood Forecasting and warning

Flood management is more effective than flood control. Thus, for its management, the important management areas are wasteland, water-storage, embankments and the construction of small scale integrated project, to be given priority. Following steps are necessary for flood plain management: (1) (2)

Scientific land use planning of the upper reaches of the Brahmaputra river basin. Identification of erosion prone areas, along the river through multi-years satellite data to delineate river reaches for flood mitigation measures. (3) Protection of natural drainage system all over the river basin while planning for developments of roads, railways, townships and industrial plants, watershed management for proper use of water resources, construction and revival of tanks etc. The important measures necessary to be taken immediately, for controlling flood and mitigating the miseries caused by it, are listed below as construction of raised platforms near the settlements of the flood prone area for taking shelter (for both man and animal) in the period of high flood. Caused factors and remedial measures for deforestation, grazing and soil erosion include are following. One method to minimize the damage due to flood will be to change the cropping pattern in such a way as to avoid the flood season. It has been suggested that the appropriate cropping strategy would be to raise early Ahu paddy from February to June followed by late transplanted Sali paddy from September to December with double cropping pattern. ISSUES CAUSES REMEDIES 1. Deforestation A) Increase in human population a) Awareness to control child birth b) Unauthorized forest removal b) Planned management c) Lack of regeneration c) People voluntary cooperation d) Inappropriate forest policy d) Effective legislation e) Increased investments in afforestation. 2.

3.

Uncontrolled and Unsustainable Grazing Soil Erosion

a) b)

Excessive livestock Lack of grass land management

a) Assessment of carrying capacity of pastures.

a) b) c)

Deforestation Faulty agriculture practices Extension of agriculture on marginal slopes Excessive road and buildings activities Landslides storms

a) Increased in trees cover b) Improved agriculture practices c) Planned construction activity

d) e)

REFERENCES [1] Centre for Natural Disaster Management,. Assam Administrative Staff College. Documentation on Past Disasters, their Impact, Measures taken, Vulnerable Areas in Assam. [2] N. El Bassan. Fundamentals of Sustainability in Agricultural Production Systems and Global Food Security. In: Sustainable Agriculture for Food, Energy and Industry, (ed. by N. El Bassam, R.K. Behl, B. Prochnow), 1–12, James and James Publishers, London, U.K. FAO, Guidelines for Land Use Planning. FAO Development Series no. 1, Rome. [3] (3) Forest Survey of India (FSI). State of Forest Report, Ministry of Environment and Forests, Government of India.2009.

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Research Forum: International Journal of Social Sciences; ISSN: 2348 4411 (Volume-2, Issue-1) ISSN: 2347-9272 (Volume-1, Issue-1) [4] [5] [6] [7]

[8] [9]

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D.C Goswami. Towards Sustainable Use of the Brahmaputra River. International Centre for Integrated Mountain Development (ICIMOD) Publication, Xu Jianchu (ed.), No. 50, pp. 20-23.2006. B. W.Pandey. Geoenvironmental Hazards in Himalaya, Mittal Publication, New Delhi. 2002. U.C. Sharma. Water Management by the Tribes of the North-Eastern Region: the Traditional Wisdom and Future Strategies. Fertilizer News 43, pp. 43–49. 1998. U.C. Sharma, and R.N.Prasad,. Socio-Economic Aspects of Acid Soil Management and Alternate Land Use Systems for North-Eastern states of India. In: Plant–Soil Interactions at Low pH (ed. by R. A. Date, N. J. Grudon, G. E. Rayment and M. E. Probert), pp 689–696. Kluwer Academic Press, Dordrecht.1995. R. B. Singh,. Disaster Management, Rawat Publication , Jaipur. 2000. R.B.Singh,. Flood Prevention and Mitigation in Disaster Prone Region of India: Case Study, eds. F. Toensmann and M. Koch, Kassel Reports of Hydraulic Engineering No 9/2000, Herkules Verlag Kassel, Germany. pp. 157167. 2000.

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