Effect of Riverbank Erosion on Livelihood - Bangladesh Online ...

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1. BACKGROUND AND OVERVIEWDeltaic sediments <strong>of</strong> Quaternary formation characterize most <strong>of</strong> the lands <strong>of</strong> Bangladesh. Thenatural setting <strong>of</strong> Bangladesh is between the Himalayas and the Bay <strong>of</strong> Bengal together withthe prevalence <strong>of</strong> tropical monsoon climate. The catchment area <strong>of</strong> the major rivers is about1.65 million square km <strong>of</strong> which only 7.5 percent lies within the border <strong>of</strong> Bangladesh(Sarker et al., 2003) that generates 1200 km 3 <strong>of</strong> run-<strong>of</strong>f annually, only 10 percent <strong>of</strong> which isgenerated within Bangladesh. In addition to vast quantities <strong>of</strong> water, these rivers carry about1.1 billion tons <strong>of</strong> sediment every year (EGIS, 2000; Sarker et al., 2003) and are responsiblefor the prevalence <strong>of</strong> flooding and riverbank erosion in Bangladesh (Elahi, 1991). Thecombination <strong>of</strong> the large discharges and heavy sediment loads with high water content fromthe annual wet monsoon, a low degree <strong>of</strong> compaction, and a large amount <strong>of</strong> run<strong>of</strong>f materialsresult in highly variable and dynamic channel morphologies (Coleman, 1969) to adjust theirbed configurations. The river channel may shift laterally by more than 300 meters (Haqueand Hossain, 1988) in any season.Study findings by Center for Environment and Geographic Information Services (CEGIS)based upon analysis <strong>of</strong> 30-year time series <strong>of</strong> satellite images reveals that the Jamuna andPadma rivers have widened more than three kilometres and destroyed about 130000 ha <strong>of</strong>floodplain land. Goodbred and Kuehl (2000) showed that during the early Holocene period,the sediments yielded by the catchment <strong>of</strong> the main rivers <strong>of</strong> Bangladesh were several timeshigher than that <strong>of</strong> present time as monsoon was stronger and the rate <strong>of</strong> sea level rise wasvery high (i.e., 1 meter per 100 years). One <strong>of</strong> the most influential phenomenons is thatclimate change is expected to disturb the sediment balance. It is difficult to forecast whetherthere will be net accretion or erosion.<strong>Riverbank</strong> erosion has important implications for channel adjustment and long-term channelchange, meander development, catchment sediment dynamics, riparian land loss anddownstream sedimentation problems. (Lawler et al., 1997). Because <strong>of</strong> poor understanding <strong>of</strong>riverbank erosion processes, river dynamics and sediment transport models are weaklyintegrated into river management strategies (Wang et al., 1997). Furthermore, suchknowledge gap complicated the relationship between flow energy and bank retreat rates(Lawler et al., 1997) as both the fluvial and non-fluvial erosion processes take place in bankerosion system and because <strong>of</strong> the duration <strong>of</strong> process and response along with the lack <strong>of</strong>information on erosion or accretion.Despite decades <strong>of</strong> research, the erosion <strong>of</strong> cohesive riverbanks remains difficult to predict(ASCE, 1998; Couper, 2004; Rinaldi and Darby, 2008). Models <strong>of</strong> cohesive river bankerosion must include a wide variety <strong>of</strong> erosional processes including fluvial erosion inducedby hydraulic forces (Julian and Torres, 2006) and mass wasting processes related to soilstrength and bank geometry (Thorne, 1982). Bank erosion is strongly influenced by the porewater pressures and the moisture content within the bank, which are influenced by hydrologicprocesses and riparian vegetation (Simon and Collison, 2002).Two principal resources <strong>of</strong> Bangladesh are its land and people. The majority <strong>of</strong> thepopulation is wholly dependent upon small land holdings (less than 0.8 hectares). It isestimated that more than half (52 percent) <strong>of</strong> rural population are functionally landless andthey have limited opportunity to cultivate their tiny land with more than two crops in a<strong>Effect</strong>s <strong>of</strong> <strong>Riverbank</strong> <strong>Erosion</strong> on Livelihood 6
calendar year. In such a condition, any loss <strong>of</strong> land by a household is devastating. Annualinundation brings moisture, silt, and fertile soil for simple agriculture; but abnormal floodingand rapid riverbank shifts seriously disrupt human settlement and activities. However,channel migration and severe bank line erosion have taken place almost every year thatdispossesses the only livelihood option <strong>of</strong> thousands <strong>of</strong> families. In addition to these, severeflooding affects cropping patterns and destroys standing crops. The socioeconomic impacts <strong>of</strong>flood in association with channel migration and bank erosion are sticking as the numbers <strong>of</strong>marginalized peoples are increasing day by day. <strong>Riverbank</strong> erosion has become a commonphenomenon along with the major and minor rivers in Bangladesh mainly due to deltaictopography and it has been forcing people to migrate or resettle in areas which are morevulnerable (i.e. mid-channel islands or chars). Such displacement exacerbates thesocioeconomic condition.Physical and engineering aspects <strong>of</strong> flood control, protection and management were the mainissues to be studied until the late 1980s to address the effects <strong>of</strong> riverbank erosion. Social,economic, demographic and other human issues were inadequately addressed (Elahi et al.,1991; Haque, 1997). Gender, age and other critical socioeconomic variables related to theprocesses <strong>of</strong> hazards-induced were studied later on (Hutton and Haque, 2004) to determinethe effects <strong>of</strong> floods and their associated displacements, specifically in relation to theimpoverishment and marginalisation <strong>of</strong> the rural poor. However, researches have rarelyexamined the effects <strong>of</strong> bank erosion on livelihood that enhance hunger and landlessness. Anattempt has been made in this study to find out the process <strong>of</strong> marginalization <strong>of</strong> the poorpeople in the paradigm <strong>of</strong> riverbank erosion.2. AIM AND OBJECTIVES<strong>Riverbank</strong> erosion is one <strong>of</strong> the major natural calamities <strong>of</strong> Bangladesh that took place inalmost every year. The effect <strong>of</strong> this disaster is widespread. The main aim <strong>of</strong> the study is t<strong>of</strong>ind out the effects <strong>of</strong> riverbank erosion on the livelihood <strong>of</strong> the affected people.Furthermore, some objectives have been identified to fulfil the study goal, which are:1. To find out the root causes <strong>of</strong> bank erosion in the study area2. Accounting the losses incurred by the affected people due to bank erosion3. To find out the rate <strong>of</strong> increased involuntary migration due to riverbank erosion andassociated food insecurity3. STUDY AREABangladesh is one <strong>of</strong> the most densely populated countries in the world, with over 140million people living in an area <strong>of</strong> 147000 square kilometres. According to the HouseholdIncome and Expenditure Survey (2010), it is estimated that 31.5 percent <strong>of</strong> its population stilllives below the upper poverty line- as measured by income, consumption, and ability to meetbasic human needs- making Bangladesh one <strong>of</strong> the poorest countries in the world. With 13people per hectare, the person-to-land ratio is among the highest in the world and is projectedto reach 20 people per hectare by the year 2020 (WB and BCAS, 1998).Being a country on the delta <strong>of</strong> the Ganges-Brahmaputra-Jamuna river system with numeroustributaries and distributaries, Bangladesh is also highly vulnerable to the effects <strong>of</strong> flooding<strong>Effect</strong>s <strong>of</strong> <strong>Riverbank</strong> <strong>Erosion</strong> on Livelihood 7
Page 1 and 2: Effects of
Page 3 and 4: EXECUTIVE SUMMARYRiverbank<
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Page 9 and 10: 4. CONCEPTUAL FRAMEWORKBangladesh i
Page 11 and 12: In-depth InterviewTo understand the
Page 13 and 14: high-flow spill channel, active onl
Page 15 and 16: 9. CAUSES OF RIVERBANK EROSION<stro
Page 17 and 18: During the study, an attempt was ma
Page 19 and 20: It is evident from the study that t
Page 21 and 22: Figure 2: Comparison of</st
Page 23 and 24: Figure 3: Loss of
Page 25 and 26: Agricultural GoodsTable 11: Agricul
Page 27 and 28: Figure 6: House Building Materials
Page 29 and 30: expending money on food consumption
Page 31 and 32: Empirical data shows that a vast ma
Page 33 and 34: Age GroupTable 15a: Migration Patte
Page 35 and 36: elocation assurance is one
Page 37 and 38: Hossain, M.Z., 1984, Riverb
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