From Risk to Costs and Benefits of Flood Mitigation in the Lower Resilience Bagmati Basin: Case of Nepal Tarai and Working Paper 6 North Bihar Ajaya Dixit, Anil Pokhrel, Marcus Moench & The Risk to Resilience Study Team From Risk to Resilience Working Paper 6 Costs and Benefits of Flood Mitigation in the Lower Bagmati Basin: Case of Nepal Tarai and North Bihar Ajaya Dixit, Anil Pokhrel, Marcus Moench & The Risk to Resilience Study Team November, 2008 Please use the following reference for this working paper: Dixit, A., Pokhrel, A., M. Moench and The Risk to Resilience Study Team, (2008): Costs and Benefits of Flood Mitigation in the Lower Bagmati Basin: Case of Nepal Tarai and North Bihar, From Risk to Resilience Working Paper No. 5, eds. Moench, M., Caspari, E. & A. Pokhrel, ISET, ISET-Nepal and ProVention, Kathmandu, Nepal, 34 pp. © Copyright, 2008 ProVention Consortium; Institute for Social and Environmental Transition; Institute for Social and Environmental Transition-Nepal. This publication is made possible by the support of the ProVention Consortium and United Kingdom's Depart- ment for International Development (DFID). The research programme is supported through DFID grant number OHM0837, NOAA award number NA06OAR4310081 and the Canadian International Development Research Centre (IDRC) Centre file 103232-001. Views and opinions expressed within do not necessarily reflect the positions of ProVention, IDRC, NOAA or DFID. The findings, interpretations and conclusions expressed in this paper are those of the authors alone. Any part of this publication may be cited, copied, translated into other languages or adapted to meet local needs without prior permission from ProVention Consortium, ISET or ISET-Nepal provided that the source is clearly stated. First Edition: 2000 November, 2008 ISBN: 978-9973-9021-4-4 Series editors: Marcus Moench, Elisabeth Caspari & Anil Pokhrel. Published by: ProVention Consortium, Institute for Social and Environmental Transition and Institute for Social and Environmental Transition-Nepal. Cover: Temporary bamboo bridge south of Gaur used during non-rainy season. The Bairgania embankment with a dysfunctional sluice is seen in background. Photo by Ram Adhar Yadav. DESIGN AND TYPESETTING Digiscan Pre-press Pvt. Ltd., Kathmandu, Nepal. PRINTED AT Format Printing Press Pvt. Ltd., Kathmandu, Nepal. Contents Key Messages 1 Introduction of the Lower Bagmati Basin: Location, Issues and Responses 3 Administrative Characteristics 4 Social and Economic Characteristics 5 Hydrologic and Geologic Characteristics 6 Climate Change Impacts 9 Evaluating Alternative Flood Management Strategies 11 The Qualitative CBA Methodology using Shared Learning Dialogues 13 Example of the Methodology Employed 15 Results along the Transects 19 Transect I: Villages along the Bagmati River. 19 Transect II: Along the Lal Bakaiya River 22 Transect III: Gaur Municipality - Bairgania Ring Embankment - Pipradi Sultan 24 Analysis: Findings from the Transects 27 Conclusions 30 Bibliography 32 Annex I: Working Paper Series 33 Annex II: Acknowledgements 34 . 1 n: asi B ati m g a B er w o e L h Key Messages n t n i osts and Benefits of Flood Mitigatioase of Nepal Tarai and North Bihar CC In the northern Ganga plains floods are common and constitute a major cause of the poverty endemic to the region. The largest investment governments have made in response to the risk of flooding has been in structural measures such as embankments and spurs. The relative costs and benefits of building embankments are widely debated but have never been systematically evaluated. Alternative strategies for managing floods also exist, but no cost-benefit analysis of such interventions has been undertaken either. The purpose of this paper is to present the results of a systematic qualitative analysis of the costs and benefits of constructing embankments in the lower Bagmati River basin, which stretches across the Nepal Tarai and into northern Bihar. The methodology we employed provides insight into the trade-offs among strategies that are similar to, but more transparent than, those used in a full cost- benefit analysis. In particular this methodology also reveals the differences in costs and benefits for different sections of the population, information not generated by conventional approaches to quantitative cost-benefit analysis which focus primarily on the aggregate benefits and costs to society as a whole. Our methodology also enriches conventional approaches because it includes many costs, benefits and dis-benefits that are often excluded as externalities. The method is useful in a data-deficient environment. Our analysis suggests that constructing embankments and spurs for flood control in the Ganga basin has different implications for different groups. In particular, while some people do benefit from embankment many also lose. Embankments and other similar structures provide short-term benefits to the communities nearest them but have negative consequences downstream and in other locations not directly protected. In addition, in a region where rivers and their tributaries transport high sediment loads, embankments play only a limited role in flood alleviation. In many cases, they block tributaries from draining into main rivers, impede the drainage of precipitation within basins, and cause sediment deposition in river beds, thereby raising their level above the surrounding land. As they age, embankments become highly vulnerable to breaching even during normal-flow stages. The embankment breach and subsequent flooding of North Bihar and the 2 Nepal Tarai by the Kosi River, which occurred as this paper was being written, was devastating. The role embankments play in flood mitigation provides a useful vantage point for exploring the link between the impacts of climate change and disaster risk reduction. As climate change alters regional weather patterns and hydrological systems, the frequency and magnitude of extreme storms and the incidence of the floods they generate are likely to increase. These changes, in turn, are likely to trigger higher rates of erosion and sediment transport within river systems. As F flow variability and sediment loads increase, the technical effectiveness of Wro orking Pm Risk to sfltoruodctsu aranld m fleoaosdu rreesl adteesdi gdniesads tteor sc oisn tlrikoel lfyl otood i nflcorweass ed.e Icnli ndeast aa-nlidm tihteed f reenqvuieronncym oefnts a R pe common across much of the developing world, it is often impossible to conduct er Nosilien quantitative assessments of the characteristics of such hazards. Much of the data . 6ce required are unavailable and even recorded trends are too short to yield meaningful analysis. As a result, it is necessary to turn to qualitative approaches in order to evaluate the costs and benefits of embankments and of alternative risk management strategies for local populations and for society as a whole. In this paper we analyze the costs and benefits of both structural flood control measures, and a wide array of local, "people-centered" strategies. These strategies range from the planting of forest buffers to the raising of houses and villages. They also include the development of early warning systems and the expansion of existing local strategies (such as the provision of boats) for coping with floods. Our analysis indicates that the costs of current structural approaches have exceeded their benefits. Reliance on such measures should be reduced, and instead a combination of people-centered and appropriately designed and maintained structures adopted. If they are designed carefully and accompanied by measures to improve drainage and address location-specific effects, structural approaches can form part of a package of complementary interventions. Where climate change impacts are concerned, the effectiveness of the approaches to flood risk management will change significantly. Increases in flow peaks and sediment loads appear almost certain to undermine the efficacy of existing embankments, spurs and other structural interventions. In particular, the associated water logging and embankment breaches are likely to increase. As a result, structural measures cannot be an effective primary strategy for responding to the increased flood risk anticipated as a consequence of climate change. In contrast, the benefits of people-centered interventions appear relatively resilient to the impacts of climate change. 3 n: asi B ati m g a B er w o e L h Introduction of the Lower Bagmati n t n i Basin: Location, RIsessupeos nasneds osts and Benefits of Flood Mitigatioase of Nepal Tarai and North Bihar CC Our study area is the lower Bagmati basin, which straddles the two districts of Rautahat and Sarlahi in the Nepal Tarai, as well as the adjacent Bairgania block in the state of Bihar in India. It falls in the doab (inter-river zone) between the Bagmati and the Lal Bakaiya rivers. It lies in the northern Ganga plain, which extends across eastern Uttar Pradesh, Bihar and parts of West Bengal. From a modern developmental perspective, the region is one of the poorest and most densely settled in the world. It represents a microcosm of other regions in the Ganga plain. As table 1 below demonstrates, the region's physical characteristics exacerbate the social vulnerability of its people. Currently, the risks of hazards are augmented by human-built infrastructure systems and the institutional, social and political context of the region and these risks will only increase as the climate continues to change. | TABLE 1 | Hazards and their intersection with human built and social, institutional, and political systems Hazards Human Built Systems Social, Institutional and Political Dynamic physical context that Ring embankments Poor data institutional base will alter due to impacts of climate change Partial embankments High social vulnerability Intense in-basin rainfall Spur Political restructuring Flash floods from Chure rivers Revetment Inappropriate conventional methods Flood Irrigation canal Conflict Changing plan-form Road and highways Poor governance Regional sedimentation: erosion, Buildings transportation and deposition Impacts due to climate change Substantial investments have been made in the construction of large-scale infrastructure, specifically irrigation systems and flood protection embankments in the Ganga plains since the 1950s. While irrigation systems have promoted agricultural growth, embankments have not been beneficial and many social activists 4 argue that these structures have not had significant benefits in comparison to the environmental, social and other costs. Despite the debate, however, embankments are still the primary mechanism for flood control that state agencies pursue. | TABLE 2 | Status of road system Our purpose in analyzing the performance of Type of road embankments along the Bagmati River is to as National Gravel Earthen Total Highway systematically and, as objectively as possible, Rautahat 41.0 83.5 200.3 26.4 evaluate the costs, benefits and impacts of both Sarlahi 279.4 102.3 446.3 30.2 existing flood control infrastructures and F Source: Road Statistics, 2004 potential alternative "people-centered" flood risk Wro orking Pm Risk to mreganioangaelm ceonntt esxtrt aitnetgoi ews.h Bicehfo trhee wy efi td.iscuss these strategies in detail, we describe the a R pe er Nsilie on . 6ce Administrative Characteristics Bairgania is one of the seventeen bocks in Sitamarhi District of North Bihar. The town of Bairgania lies in this block. According to 2001 census, Bairgania has a population of 34,821. A meter gauge or narrow railway line to Raxaul running parallel to the Nepal-India border passes from Bairgania. Since no information on Bairgania Block, in Bihar is available, the following section focuses on Nepal. Besides, the two regions are similar. In Nepal, the Bagmati Basin lies in Rautahat and Sarlahi districts, which extend from the Chure hills (the foothills of the Himalaya) in the north to the Nepal- Bihar border in the south. Rautahat is one of 11 districts in the central development region of Nepal and lies in the Narayani Zone south of the capital Kathmandu. The district has 97 village development committees (VDCs), which are the lowest administrative level of government. Rautahat covers an area of 1,126 km2 and, according to the 2001 census, has a population of 545,132 living in 88,162 households. Sarlahi District, which falls within the large administrative region of Janakpur Zone, is located east of Rautahat District. It contains 100 VDCs and covers an area of 1,259 km2. As of 2001, Sarlahi District had a population of 635,701 living in 111,076 households. Large portions of both districts were covered by forest until the 1960s. This forest was part of an area known as the Char Kose Jhadi, where, until the 1960s, malaria was endemic. After malaria was eradicated, the inflow of people increased gradually. At the same time, the government investments in water development projects, including flood control. Before the construction of the East-West Highway (the main transport corridor extending right across Nepal and lying in the northern bhabar1 region of Rautahat and Sarlahi districts), Gaur, the district headquarters of Rautahat, had to be | TABLE 3 | Status of land ownership Landholding in flood affected area Landholding outside flood affected area River Basin HH having land (%) Average holding size (ha) HH having land (%) Average holding size (ha) Bagmati 49.7 0.91 24.0 0.86 1 Bhabar - a narrow, but deep zone of boulders, gravel and coarse sediment deposited at the base of the Chure hills – the southernmost range of hills before the Gangetic plains.