Managing floods in Ganga-Brahmaputra Meghna basin

Though the Himalayan river basins get affected by regular inundations during high flows in monsoons, they rarely get the media attention they deserve. Large tracts of these annually inundated lands are part of the Ganga-Brahmaputra-Meghna basin (GBM basin). Some of the flood affected areas of GBM basin are among one of the most densely populated zones of the world and also home to a number of large cities like Kolkata, Dacca, Patna etc. Being flood plains, annual inundation is a normal hydrological phenomenon in the area. The people living in these areas have learned to live with inundations for thousands of years. But, a mélange of causes have forced the residents of the flood plains of the GBM basin to face increased level of inundation quite frequently and they include both natural and human causes. Climatic profile The Himalayan rivers like Ganga and Brahmaputra drain 75 percent of the total basin runoff in a brief period of only three months of the monsoon (Bandyopadhyay and Gyawali,1994:12). There are several flood enhancing factors like techtonically active hinterlands, very high rainfalls in the catchment areas in a short period, local high ground water levels, low relief, obstruction of drainage by infrastructure and temporal coincidences of peak discharges of Ganga, Brahmaputra and their tributaries (Bandyopadhyay, 2009:73). There seems to be a relationship between the floods and El Nino Southern Oscillation phenomena as well, with 6 out of 7 devastating floods in South Asia last 40 years occurring in La Nina years (Meyers et al., 2007). Perspective matters Floods are largely and wrongly being viewed as hazards. In reality, they are integral components of hydrological cycle and have their own share of ecosystem services and benefits for human community (for example, forming soil and enhancing soil fertility with fresh sediments, recharging aquifers, transporting fish and other bio diversity). Reductionist arithmetic hydrological thinking fails to accept flood as an inevitable natural event. Outdated engineering interventions like large dams and flood embankments based on that very same reductionist hydrological thinking has resulted in disruption of the natural flow of the drainage systems (Bandyopadhyay, 2009:77). This has only increased the problem of water logging and affected the ecological characteristics of the flood plains of the GBM basin. Urban development: Planned or unplanned? In flood prone large cities of the basin, be it Lucknow, Patna, Kolkata or Dacca, the normal drainage system is disrupted by the unplanned bulk of built up area and destruction of naturally swampy region in the name of development with half hearted or insufficient environment impact assessment (in some cases with a blatant disregard for environmental laws or consideration of local geomorphology). The natural drainage slope of the urban areas is also seldom considered. As a result, the urban water logging is increasing. So is the urban runoff. The sections which are getting the short end of the stick are the common people, economy and ecosystem of the region that remains stalled for days during the monsoon and post monsoon. There is a dire need to regulate urban development keeping in mind the local geo hydrological characteristics. The way ahead: Shifting the paradigm There is a serious need of a paradigm shift in the flood management system of not only GBM basin, but South Asia as a whole. The first stepping stone should be accepting the fact that absolute control and protection against flood can be seldom achieved as all flood control methods have limited effectiveness. Inundations are inevitable natural events in flood plains and they don’t follow the administrative boundaries either. So, instead of an administrative unit based management there should be a basin based management strategy. Of course, this type of strategy demands regional international co-operation, in the case of GBM basin, between Nepal, India, Bangladesh and Bhutan. Instead of creating more traditional engineering interventions, giving the water a proper drainage and sink should be considered. The old drainage channels, wetlands, swampy regions and ponds can help in this regard. The wetlands and swamp work as natural sink for the flood water and help in reducing runoffs. On an official level the policy is to conserve the existing wetlands. But, unofficially the wetlands keep vanishing under shady land grabs often under the closed eyes of the very same people who were supposed to save them, sometimes in spite of court orders to halt the land filling. ‘Safe-fail’ instead of fail-safe Even when preliminary steps and cautions are taken to manage the inundation, in a flood plain with huge population density like the GBM basin, damages due to the flood will be extensive. There is a need for a sustainable flood belt development system that is a ‘safe-fail’ instead of ‘fail-safe’ (Anonymous, 2003: 278) and a spatio-temporal multi-tier flood management system; the existence of international, national, state level and district level committee that work on a pre-event, during event and post-event basis. The word ‘fail’ here signifies the fact that floods cannot be stopped altogether using this management system. But, it fails in a ‘safe’ way that minimizes the damages caused by the floods as per humanely and sustainably possible. Flood vulnerability analysis should be carried out on a mass level on the major river basins. The available models and data on climatic trend and real time situations should be intensely analysed and predictions of rainfall and possible flood predictions should be made which are then extensively circulated through mass media. The system is still there in India and Bangladesh. But the efficiency remains under question.  Also a trans-boundary basin strategy needs continuous dialogue and creating a common forum with historical perspective. Building the base with data Developing early warning system models for flood in GBM basin have been largely inhibited due to non-availability of trans-boundary flow data. The classified trans-boundary data on the flow regimes of these rivers should be openly available to the researchers for the creation of better models to understand the mechanism of flood formation in the basins. There will also be an inevitable debate on how much data is required or sufficient for proper modeling of the flood hazard in the area and creating a proper management strategy. A preferable solution can be to identify the available actionable data, start with it and then keep documenting the ongoing data for future modification of models and strategy. There is also a need of standardizing the available data from different countries for a wholesome basin based approach. At the grass root level the vulnerable groups should be prepared for risk management to reduce vulnerability and to respond to disasters. There should be some local level response team in place during and after the event for rescue and relief. During this type of activity, there is a strong current of political and group favourism that goes on, sometimes very openly. The decision makers on top and the general citizens should be proactive and knowledgeable enough to avoid and stand against this type of attitude. There is a need to include all the stake holders in the planning process and take a negotiated approach as the issue in trans-boundary. Inclusiveness of diverse stakeholders, a new trans-disciplinary knowledge base created by the emerging science of eco-hydrology, economics and new institutional theories should be considered. Last but not the least the planning process should be on going. The system should not be put on a hold as the flood waters recede and shoved into the shelf for the next monsoon until the waters rush in again. Instead the idea sharing, conversations and awareness about flood should go on around the whole year. In the end, the goal should not to be to resist flood, but to yield and survive the situation. The situation is going to get harsher with predicted changes in global climatic patterns in the next hundred years. A well structured basin based plan of managing extreme global hydrological events like flood and drought is an immediate requirement in this situation for sustaining the economy and ecology of the region. How far we can do it is what the time will tell. References Anonymus. (2003). Water for People, Water for Life. New York: UNESCO and Berghahn Books. Bandyopadhyay, J. (2009). Water, Ecosystem and Society: A Confluence of Disciplines . New Delhi: Sage Publications India Pvt Ltd. Bandyopadhyay, J., & Ghosh, N. (2015). Holistic Engineering and Hydro-Diplomacy in the Ganges-Brahmaputra-Meghna basin. Economic and Political Weekly , XLIV (45), 50-60. Bandyopadhyay, J, and Gyawali, D. "Himalayan Water Resources: Ecological and Political Aspects of Management." Mountain Research and Development 14, no. 1 (1994): 1-24. Basu, P., Mukhopadhyay, S. & Jayaraman T. (2001). Climate Change Adaptation in Flood Plain of West Bengal. Kolkata. Meyers, G., Mcintosh, P., Pigot, L., & Pook, M. (2007). The Years of El Niño, La Niña, and Interactions with the Tropical Indian Ocean. Journal Of Climate , 20, 2872-2880.

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