Riverbed siltation along with back water effect due to sea-level rise and high tide is leading to prolonged water-logging in south-west Bangladesh in recent two to three decades. Gradual siltation is the main source of the problem on the riverbed triggered by inadequate runoffs in the southern reaches caused by the polders constructed under the Coastal Embankment Project (CEP) during the sixties. The consequent losses in agricultural production due to the inundation of about 128 thousand hectare crop land were noticed in Jessore, Satkhira and Khulna districts that directly affects the life and livelihood of about one million people. Continuous climate change would put extra burdens on the social and economic challenges that the poorest already face, emphasizing and increasing their vulnerabilities due to the dependence of their livelihoods on climate sensitive natural resources and their weak social protection structures. For removing water logging effect, plinth rising and elevating the local habitats and physical infrastructures can be considered as an immediate and short-term measure whereas operation of Tidal River Management (TRM) technology might be considered for long-term or permanent solution for raising the low lands or beels. The dead or silted-up rivers, canals, ponds and irrigation channels can be excavated or re-excavated by operating the major workfare social safety net programmes of the government like Food-for-Work (FFW) or Cash-for-Work (CFW) and the excavated soil can be utilized for creating, maintaining or raising the rural roads, polder/embankment and related other infrastructures which are quite crucial for mitigating the flood or water logging problem in the region. For continuing crop production local people are engaged in floating agriculture, crop production with Sorjan method, and fish cultivation in lowland to utilize the water-logged land around the southern region. They elevate and widen the surroundings of that water-logged land utilized for vegetable and fruit production. Such local practices can properly be screened and piloted befitting to climate change adaptation to the water congestion areas of the country. The interventions may also be applicable to other agro-climatic regions or countries suffering from the similar problem.
Keywords barrage, climate change, dam, embankment, polder, social safety net, water congestion
Laboratory of Plant Ecology, Department of Crop Botany, Faculty of Agriculture, Bangladesh Agricultural University, Bangladesh
ReceivedApr 18 2014 AcceptedSep 19 2014 PublishedDec 17 2014
CitationAwal MA (2014) Water logging in southwestern coastal region of Bangladesh: local adaptation and policy options. Science Postprint 1(1): e00038. doi: 10.14340/spp.2014.12A0001
Copyright©2014 The Authors. Science Postprint is published by General Healthcare Inc. This is an open access article under the terms of the Creative Commons Attribution-NonCommercial-NoDerivs 2.1 Japan (CC BY-NC-ND 2.1 JP) License, which permits use and distribution in any medium, provided the original work is properly cited, the use is non-commercial and no modifications or adaptations are made.
FundingThe study was financed under the Research Grants Scheme (RGS) of the National Food Policy Capacity Strengthening Programme (NFPCSP). The purpose of the RGS was to assist in improving research and dialogue within civil society so as to inform and enrich the implementation of the National Food Policy. The NFPCSP is implemented by the Food and Agriculture Organization of the United Nations (FAO) and the Food Planning and Monitoring Unit (FPMU), Ministry of Food of the Government of the People’s Republic of Bangladesh with the financial support of EU and USAID.
Competing interestThere are no relevant competing interests to disclose.
Ethics StatementThis work doesn’t form part of any study or trial; it is part of a regular work.
Donation messageAny financial support would be highly appreciated to further advance this research.
Corresponding authorMd. Abdul Awal
AddressLaboratory of Plant Ecology, Department of Crop Botany, Bangladesh Agricultural University, Mymensingh 2202, Bangladesh.
Peer reviewerRui-Song Quan
Science Institute, East China University of Political Science and Law, China.
From beginning of the 21st century a new problem “water logging” (the long-term inundation of areas as a result of inadequate drainage) arose in south-west coastal region of Bangladesh. It has become an increasing problem in recent years for a variety of reasons: natural changes in river flow; increased sediment in riverbeds due to reduced sediment deposition on floodplains protected by embankments; and a lack of proper operation and maintenance of sluice gates of the polders i.e. circular embankments 1-3.
Water-logging is a pressing concern at the backdrop of climate change that becomes worsens for the people of southwest Bangladesh. The prolonged water-logging has caused significant displacement presenting humanitarian challenges in safe water supply, sanitation, shelter, food security, and employment opportunity. There are areas where people are compelled to live in waterlogged condition for nine months in a year; even many cultivated crop lands are permanently inundated losing valuable agricultural production especially rice. Socio-economic and agricultural activities have largely been hampered due to water logging 4, 5. The local people are seriously shocked especially in the rainy season when peak monsoon intercepts the region. Loss of livelihoods due to submergence of land often forces male to go far away for weeks in search of alternative livelihoods. Women being the primary care giver of the family are compelled to live within the waterlogged premises, shouldering the entire burden for managing and cooking food, collecting drinking water, taking care of the family members and their livestock as well. Social demoralization, diseases, unemployment and migration have increased in the locality where the places protracted by water-logging 6-9. People living is seemed either bitter fate or curse beyond the grip. The marooned people face portrayed with uncertain hopelessness, having no options but to accept their destiny against their own will 1.
Due to the permanent water congestion sudden flood is occurred during the rainy months. In the other words, the water logging situation causes recurring flood in every monsoon. Among the affected areas, Satkhira is the worst hit and experiencing severe and year-round water logging. The situation makes agriculture activities impossible. Biodiversity is threatened and cultivable land has shrunk. The situation is so harsh that there is no other way out, but to live with water. Although the dimension of water logging problem was little in the initial stage that slowly increased over the years but the situation has been compounded from 2006 2 and a maximum disaster was observed during the downpour of 2011 monsoon 10-12. The situation is expected to worsen more to the days to come. The cost of people’s suffering therefore must be weighed against the cost of adaptation.
While there is a very little specific research on the water logging problem, it is believed that climate change could further exacerbate this issue through changes in sedimentation and river-flow, increased monsoon rainfall and retarded discharge of rivers due to back water effect and sea-level rise 13-16. Although the water logging sometimes caused large scale disaster in the regions but the research initiatives for mitigating the problem have not been taken into account so that specific policies can be tailored to minimize the risks and maximize the benefits for individuals, households and communities. Therefore the study was aimed to analyze the problem for formulating befitted policy in order to overcome the water logging problem in south-west coastal region of Bangladesh.
Water logging is happened when the soil is so filled or soaked with water. When the water table rises to such heights that the soil pores become saturated, thus displacing the air, the land is said to be waterlogged. Water logging is full (i.e., 100%) when water table rises to the surface. However the process of water logging starts even when the water table is quite below the surface. An area may be regarded as waterlogged in this study when the water level above the ground is too high that does not permit an anticipated activity, like agriculture. It occurs when the rate of accumulation of water through rainfall or some other means exceeds the combined rates of drainage, percolation and evapotranspiration of a catchment or when flood water submerges an area 17. Water logging may differ from flood situation in such a way that the flow of water is almost nil in former case as the water body is arrested by a boundary (like polder). An area may be affected by both water logging and flood concurrently; however, the later may not persist to a long time.
Water logging is a global phenomenon, but the way of its prevention and mitigations to date have received little attention. The problem is very much site specific, nevertheless some methods for preventing and mitigating the drainage congestion due to water logging can be mentioned from the literature like establishment of shallow interceptor drains 18, discharging the congested water by installation of drainage pump 19, 20, minimizing the accumulation of congested water through rain water harvest 21, downing water table by groundwater recharge 22, lowering groundwater levels through deep tube wells 23, subsurface drainage systems that consisting of open and pipe drains 24, dry drainage that involves the allocation of areas of fallow land, which operate as evaporative sinks drawing a stable flux of water (and salt) from irrigated areas 25, plantation or stands of halophytes (salt-loving plants) those can transpire sufficient water to lower water tables, thereby ameliorating water logging and presumably inundation 26 etc. Interestingly, windmills are also used to pump water into the embanked river to prevent water logging of the lowlands (polders) behind them 27. In some cases, drainage with or without raised beds are the best way to overcome water logging and inundation in most areas 28. Biodrainage of water table through enhancing evapotranspiration by strategically planted trees can be a feasible option for controlling water logging 29-31. The tree species like Eucalyptus spp., Prosopis juliflora, Tamarix aphylla etc are found to be the best bio-drainers from the waterlogged areas 32.
Due to special geographical location and climate, the water logging is one of the most serious hazards now-a-days in southwest coastal region of Bangladesh. The landscape of the present study site is too fragile as the site is under storm surge due to tropical cyclone, sea-level rising, tidal excursion and back water effect, thus intrusion of saline water from the Bay of Bengal is common. Therefore, exploring the best adaptation practices is time demanded with the prevention and mitigation of water logging in the region.
Qualitative and quantitative as well as primary and secondary sources of data from the various waterlogged areas like Jessore, Satkhira and Khulna districts have been used in the study. The tools used for primary data collection from affected villagers include focus group discussion (FGD), participatory rural appraisal (PRA) sessions and case studies. The primary data using those tools were collected from Sufalakati Union of Keshabpur Upazila (sub-district) of Jessore District, Tentulia and Tala Sadar unions of Tala Upazila of Satkhira District and Sachiadah Union of Terokhada Upazila of Khulna District (Figure 1). The affected areas for primary data collection were selected with the consultation with Department Agriculture Extension (DAE)’s officials like Deputy Director, Sub-district Agriculture/Extension Officer etc. The most affected villagers or households were randomly selected and accumulated with the help of the local administrative personnel like Sub Assistant Agriculture Officer, Union Council Chairman, Union Councilor or other Local Leaders.
Red squares represent each study sites. Data were collected through FGD, PRA and case study.
Reprinted from “Banglapedia: National encyclopedia of Bangladesh.” Retrieved from http://en.banglapedia.org/index.php?title=Keshabpur_Upazila (for (a) Keshabpur Upazila), http://en.banglapedia.org/index.php?title=Tala_Upazila (for (b) Tala Upazila) and http://en.banglapedia.org/index.
php?title=Terokhada_Upazila (for (c) Terokhada Upazila). Copyright (2012) by Asiatic Society of Bangladesh. Reprinted with permission.
The FGDs were conducted at two phases. The first phase FGD with waterlogged villagers was conducted to collect the views and opinions of local people on the various aspects of water congestion. With utilizing the other sources of data, preliminary result was drafted following the completion of first phase FGDs. To cross validate the preliminary results, the second phase FGDs were also conducted from the places where the first phase FGDs were done. The participants of those two time’s FGDs were different. PRA sessions were conducted to reality-check the study’s proposed policy options and conclusions. Case studies based on experiences of villagers were done to illustrate and identify key challenges to be addressed by government and/or non-government agencies. Consultation meetings were conducted with relevant government officials (Table 1) who are working with related tasks like Bangladesh Water Development Board (BWDB), Department of Agriculture Extension (DAE), Department of Environment, Department of Disaster Management, Relief and Rehabilitation Office etc at national, regional, district and sub-district level. Consultation meeting was also conducted with NGO officials working in the locality. The government officials and NGO program staffs were contacted prior to the consultation by electronic mail or telephone explaining the objectives of the consultation. The discussion was always done with institutional managers or chief of the office staff.
1 Ministry of Agriculture;
2 Ministry of Disaster Management and Relief;
3 Ministry of Water Resources;
4 Ministry of Environment and Forests
Rainfall data from 1948 to 2010 were collected from Bangladesh Meteorological Department (BMD). The dataset constituted rainfall data from 35 observatories throughout Bangladesh. Historic means of rainfall were calculated and future projections were also made to 2050, 2075 and 2100. Other secondary data like crop land areas, number of people and infrastructures like houses, roads etc affected by water logging were collected from government offices, newspapers, published and unpublished reports and by consulting with browsing on internet.
It is clear from monthly rainfall distribution that minimum rain occurs from November to April—the period which is regarded as the dry period (i.e. non-monsoon) in Bangladesh (Figure 2). In contrast, most rain occurs during the remaining months which regarded as wet period (i.e. monsoon). Nevertheless, the period from June to September (i.e., peak monsoon) receives the lion share of the total rainfall throughout the year. The rainfall of Khulna division (the study area located within this region) during the peak monsoon period was remarkably lower as compared to that at national average. It is evident from future projection (by linear regression) that although summer rainfall is found almost static but autumn rainfall is in increasing trend in Khulna Division as well as throughout the country i.e., national average (Figure 3). Recently, Mondal et al. 33 have also analyzed the rainfall data for a period of 63 years (1948–2010) at Khulna region and found that the number of rainy days in a year and the maximum number of consecutive rainy days are found to be increasing in the southwest coastal region of Bangladesh. They also found that the rainfalls have increasing trends where most increment will be occurred during monsoon. Like the result of the present study, there are some evidences also found from Mondal’s study that the monsoon is strengthening towards the end of the season. These along with increasing future projection in autumn rainfall suggest that water congestion in the days to come would be prolonged in the locality even after end of the monsoon.
Data represent the mean from 1948 to 2010.
Winter, spring, summer, and autumn seasons represent the months of December-January-February, March-April-May, June-July-August, and September-October-November, respectively.
Bangladesh is a low-lying deltaic country. Topographically the country may be divided into alluvial plains and hilly areas. More than 90% of the total area of Bangladesh is low land, an alluvial plain formed by the sediments of the several great rivers and their tributaries and distributaries which traverse the country. Elevations of the plains are less than 10 m above the sea level; elevation furthers decline to a near sea level in the coastal south. Most of the coastal parts and associated inland of Khulna (within where study was carried out) and Barisal divisions lie within 1 m from sea level (Figure 4). Adhikary et al. 34 found from a Digital Elevation Model study that the southwest region of Bangladesh is dominated by flat topography. The landscape has a low ridge and a basin relief crossed by many tidal rivers and creeks. Local differences in height are generally less than 1 m. Maximum tidal ranges vary from 2.5 to 3.5 m (spring tide). During neap tide, the variation ranges from 1.5 to 2.5 m.
Reprinted from “National Plan for Disaster Management 2010-2015,” by Disaster Management Bureau, Disaster Management & Relief Division, Ministry of Food and Disaster Management (2010) Retrieved from http://www.lcgbangladesh.org/derweb/doc/Final Version Nataional Plan for Disaster (2010-2015).pdf. Copyright (2012) Department of Disaster Management (DDM), Ministry of Disaster Management and Relief, Government of the People's Republic of Bangladesh. Reprinted with permission.
Global warming is raising sea levels around the planet by 2–3 mm each year. However, the distribution will not be uniform due to ocean density and circulation changes. The rise along the Bangladesh coast could be 0–5 cm more than the global average. That only adds to bigger problems in the Ganges–Brahmaputra delta (within where Bangladesh is located), which is sinking so rapidly that the local, relative sea level may be rising by up to 2 cm each year. It is found from the analysis of satellite data that relative sea-level rise is occurring for Bangladesh is 8–18 mm/yr whereas the tide gauge analysis from southwest Bangladesh found that mean sea level is climbing at 5 mm/yr, but high-tide level has risen by 15–20 mm/yr in some spots 35. Mondal et al. 33 analyzed tidal water levels of the Rupsa-Pasur River at Khulna and at Hiron Point that located near to the Bay of Bengal for a period of 74 years (1937–2010) and found that the annual maximum tidal high water level is increasing and the annual minimum low water level is decreasing at a rate of 7–18 mm and 4–8 mm/yr depending on the locations, respectively. The possible reasons for the decreasing trends in annual minimum water levels could be the reduction in the sweet water flow from upstream areas or the reduction in storage areas of saline tidal water or both. The increasing trends in annual maximum water levels could result either from silting up of the rivers, reduction in flood tide propagation areas, or a rise in the sea level, or a combination of these factors.
Tidal ranges are higher in the rivers immediately south of the study area than in areas closer to the Bay of Bengal. The tidal ranges are 10–30 cm higher during the wet season than in the dry season 36. The projected sea-level rise will be occurred in the Bay of Bengal 15–62 cm at 2080 (Table 2, 37). Sea level rise will aggravate the drainage congestion, water logging and flooding problems that are already severe in the urban and peri-urban areas of Khulna 38.
Source: Solomon et al. 37
Level of urbanization or simply urbanization may be defined as the proportion of a region’s population that lives in towns and cities. Urbanization is the increasing number of people that migrate from rural to urban areas. It predominantly results in the physical growth of urban areas, be it horizontal or vertical. As per recent UN data, approximately 25% of Bangladesh population currently lives in urban areas. Level of urbanization in Bangladesh in 2011 was found as 28.4% 39. Urbanization process is relatively slow in Khulna areas due to collapse of the major industries like jute, pulp, paper and match industries etc in the region 40. The average urbanization rate of the Khulna Division is 17.99%, and the rates are 9.95, 18.58 and 33.54% respectively for the district of Satkhira, Jessore and Khulna where the study was carried out 41.
Geographically a lot of rivers–crisscrossed the study area that are used for draining water from the locality. Some of the main catchments and their drainage divides are mentioned.
Khulna-Jessore Drainage Area (K-JDA): It is one of the major waterlogged areas (100,600 ha) in the region that comprised the south-eastern part (27,200 ha) and north-western part (73,400 ha). PDO-ICZMP 36 broadly explained the drainage system of K-JDA. Briefly, the south-eastern system of K-JDA is comprised of three main catchments: Beel Dakatia or Polder 25 (14,300 ha), Polder 27 (4,900 ha) and Polder 28 (8,000 ha). Previously the western part of Polder 27 drained towards the Hamkura River. This river is no longer functioning, and all drainage has been diverted into the Upper Sholmari. Beel Dakatia also drains into the Upper Sholmari. Polder 28 drains into a constructed canal named Ramdia-Joykhali Khal.
The north-western part of K-JDA comprised (i) Mukteswari‒Teka ‒Hari River basin (45,200 ha) that consists of 8 large beels (low-lying pockets of the landscape) such as Kedaria, Kapalia, Paira, Barunia, Khukshia, Rudagara, Madhugram and Bhaina, and (ii) Harihar‒Upper Bhadra River basin (28,200 ha) that contains some small and medium sized beels such as Pajia, Patra and Baruli etc. The former basin comprised two main catchments: Mukteswari (29,200 ha) and the Hari (16,000 ha). The Hari drains water of its own catchment, plus the discharge from the Mukteswari. The later basin also comprised two main catchments: Harihar (16,500 ha) and Upper Bhadra (11,700 ha). The Upper Bhadra drains water of its own catchment, plus the discharge from the Harihar.
Kobadak River basin: Kobadak River is 180 km length that originated from Bhairab River at Chaugachha, Jessore and outfalls at Khalpetua River at Koyra, Khulna. It is one of the major inland rivers in southwest region of the country. Total catchment area of Kobadak River is 800 km². It drained water from the many catchments from Chaugachha, Jhikargachha and Keshabpur upazilas of Jessore District and Tala Upazila of Satkhira District. Following the siltation of Kobadak, water logging problem began to appear seriously in some of those catchments.
Atharobaki-Chitra Rivers basin: Bhuter beel that constituted from Shachiadah, Chagladah and Terokhada unions of Terokhada Upazila in Khulna District drained to adjacent Chitra River. The Chitra finally drained to Atharobaki River and Kaliabordia River. Atharobaki River partially dead due to siltation however Kaliabordia River is still alive. Nevertheless 5329 ha crop land of Bhuter beel become waterlogged due to recent siltation of Chitra River (Figure 5).
In order to drain Bhuter beel the central part of Chitra was excavated by the BWDB but that was silted-up again.
The responsibility for water management is carried out by the BWDB. The BWDB is operating TRM programs continuously from one beel to another. Additionally, they are also continuing some excavation or re-excavation programs into the rivers or canals. The BWDB maintains about 37 polders with 1566 km of embankments and 282 drainage sluices that constructed by CEP in the study regions.
The major cause for water logging can be explained as rising of riverbed due to siltation as influenced by retardation of upstream river flow for human intervention, as well as deprivation of floodplain (low land, locally so called beel) to silt deposition due to embankment or polderization.
The main source of river flow of the southwest rivers of Bangladesh is Ganges. The rivers of that region were much living and the ecosystem was rich with sweet water due to strong upstream pressure. During the nineteenth century the rivers of that region were detached from the source Ganges due to death of Mathabhanga (a branch of Ganges; Figure 6). Consequently some rivers named Kobadak (locally Kopotakho), Bhairab and Betna (which had linkage with the Mathabhanga River) begun to lose their speed thus siltation occurred at the time of ebb-tide due to the lack of upstream river pressure. Gradually the silt are started to deposit into those rivers and can’t pass the upstream water flow 1. Soon after independent of Bangladesh in 1971, India government constructed Farakka barrage over the Ganges (only 16.5 km from the Bangladesh border) which drastically retarded river flow to the entire southern part of Bangladesh. Other local human interventions on the rivers are also considered for the siltation of riverbed.
Reprinted from Banglapedia: National Encyclopedia of Bangladesh, by Md Abdur Rob. Retrieved from http://www.bpedia.org/G_0027.php. Copyright (2012) Asiatic Society of Bangladesh. Reprinted with permission.
River course is a dynamic process which governs any agro-ecological system. In course of time, however, the aforesaid silted up rivers became a curse instead of a blessing 42. In early 1960s, the East Pakistan Water and Power Development Authority (EPWAPDA) established the Coastal Embankment Project (CEP) to convert the seasonally flooded coastal wetlands into reclaimed land for permanent agricultural production under the Green Revolution Programme (GRP), as well as to protect human settlements from the cyclone, tidal surge and associated floods, saline water intrusion etc. A series of embankments and polders were constructed around the southern coastal region of the country as a part of the CEP. With that Water Master Plan 37 polders, and associated 1566 km embankment and 282 sluice gates were constructed in the Khulna, Satkhira and part of Jessore districts 1, 43.
Before establishing the embankment, boat was only the single type of vehicle used for communication in the region. After polderiation, the embankments are used as roads for communication. During construction of embankments, many cannels and discharge path of water being closed but relatively less number of culverts, bridges or opening is developed at that time. Additionally, maximum culverts didn’t construct with necessary height for water discharge and pillars of bridges also help to siltation. Therefore, problem arises for discharging the water from those regions. Because the slope of land in those regions is north-south oriented but maximum embankments are developed to east-west face. So rivers and channels lost their natural flow and create water logging at that region 1.
The polder/enclosure system was developed and implemented in line with the “green revolution” paradigms of “grow more food” 44. The idea was to promote cultivation of HYV crops in dry lands with controlled irrigation, thus the output of that large-scale engineering intervention was found obviously good with producing rice 2 to 3-fold higher than ever before. It was also noticed that the CEP area was out of food insecurity even when the whole country fall scarcity of foods 1. But day by day, the improper operation and poor management of polders/embankments and their sluice gates (Figure 7) have caused a series of problems, and accordingly within a few years, the negative impacts of the project began to appear including the siltation of riverbeds, increased saline intrusion, the narrowing of river estuaries and changes in the normal morphological processes of river (Figure 8). Consequently, river flows were affected and many rivers silted up, affecting navigation. The biodiversity especially for flora species of the region became degraded.
By the early eighties polders became a bane rather than a boon for the people, as rivers failed to maintain their natural courses. Tides deposited silt on the riverbeds and sluices, rather than the floodplains, for more than two decades, halting the natural flow of the rivers and sluices of the polders. The consequent dearth of land formation left floodplains inside the polders lower than riverbanks 45 i.e., inside the polders, the wetlands subsided due to non-deposition of silt and gradually took the shape of lakes (i.e., beel). As a result river flow discharges to over the beel. Thus rainwater could not drain from the area’s leading to chronic water logging. By 1990, over a hundred thousand hectares of land in Khulna, Jessore and Satkhira districts became waterlogged, and agriculture became impossible 1. Another concern is that the elevation of greater Khulna area is much lower (even less than a meter) than that the other coastal parts, a significant proportion of which again falls below high-tide level 46. Moreover, the embankments are at risk of overtopping (http://www.cegisbd.com/pdf/climate Change Brochure.pdf; site accessed on October 29, 2014) due to storm surge, high tide or sea-level rising, leading to saline water-logging within the polderized areas.
Figure 9a shows the number of people who were affected due to monsoon flooding of 2011 and subsequent water logging in the three south-west districts of Bangladesh. Much variation was found in the number of affected people for the different sub-districts (upazilas). The higher number of people was affected in Tala and Sadar upazilas of Satkhira District followed by Asasuni and Kalaroa of the same district. The number of affected people was found lowest in Abhaynagar and Bagherpara upazilas of Jessore District while the other reported upazilas ranked in middle. The water logging during 2011 monsoon was so intense in the recent times when about one million people were affected in the different upazilas of those three districts.
The maps were drawn using GIS software like ArcView GIS 3.3/ArcGIS 9.2.
It is also reported from a recent field study that about 48, 69, 36, 55 and 39% of the total population respectively from Sadar, Tala, Kalaroa, Debhata and Asasuni upazilas of Satkhira District; about 19, 11, 3 and 19% people respectively, from Keshabpur, Monirumpur, Abhynagar upazilas of Jessore District; and 19% population from Paikgachha Upazila of Khulna District were affected by water logging during the 2011 monsoon 47, 48.
Water-logging has shrunk the valuable cultivated crop land even in the dry season. An area of more than 128,000 ha crop land is affected due to water congestion from those three coastal districts of Bangladesh (Figures 9b, 10). In the south-west region of Bangladesh there exists about 200,000 ha (including the 128,000 ha from reported three districts) of natural and artificial wetlands (unpublished report). Due to water congestion, the flooding stays for 60–90 days, many trees like jackfruit, papaya etc do not survive and the waterlogged lands have not produced any yield over past years.
Within the last two to three decades, many of the mighty rivers have already been fully silted up and people have been suffering heavily by the water-logging. At least 6 months in a year, the marooned people especially women are bound to live surrounded by water (Figure 11). Moreover, frequent cyclones and even any above normal high-tide flood, increased salinity etc destroy all kind of agricultural productions. In addition to “normal” patterns of flood that occurs in Bangladesh in almost every year, water-logging (the long-term inundation of areas as a result of inadequate drainage) issue is added to as another climate shock which has become an increasing problem in recent years.
Reprinted from “Floods, Water-logging in Satkhira” by Star National Desk, 2012. Retrieved from http://archive.thedailystar.net/newDesign/news-details.php?nid=220513 or The Daily Star, Tuesday, January 31, 2012. Copyright (2012) thedailystar.net. Reprinted with permission.
Water logging destroyed houses, latrines and source of safe drinking water, disrupted communication and the rhythm of daily life, killed off fruit trees and reduced the number of domestic animals (data not shown). Schools became closed and children were deprived of education during water logging period. Many farmers turned into fishers as agricultural lands were submerged. Hundreds of thousands lost their occupations and became destitute.
Vegetable production system is completely damaged by flood or rain and local food storage is not enough to cover the needs. Food supply, in terms of quality, quantity and diversity become less than the demands during the peak water congestion period. The market price is reported to increase by about 10–15% during 2011 water logging event 47. Most of people did not have ability to afford sufficient food for their households. Unemployment is the major cause to purchase the daily needs. Due to acute financial crisis, many people cannot have three meals a day even after removal the congested water. Without food or safe drinking water, many villagers have been forced to migrate elsewhere (especially city) as life became difficult to support. Most people want to go back their previous waterlogged free rice-production based condition in the regions.
It is reported that many households were reported to move relative’s homes and many other sheltered on the roads, highways, embankments etc during peak water logging period. It was observed that the local inhabitants have already started to elevate their homestead especially house bed (i.e. plinth rising), latrines, tubewell, roads etc (Figure 12). However, the crisis of soil mass is acute in those regions.
The affected people have already started to practice some local adaptations in agricultural production around the southern region of Bangladesh which vary from location to locations. Due to the worst experience from recurrent water logging problem, most of those adaptive strategies can be practiced to reduce the negative impacts of this slow onset disaster. Some of those adaptation practices are mentioned.
A floating bed (locally known as “baira”) is constructed with the help of water hyacinth and bamboo. Decomposing plant derbies can be act as an important source of organic matter and crop nutrients in floating agriculture 49.
The basic construction of the floating bed requires bamboo poles with some other simple tools. The bed is then built up of layers of aquatic weeds, mainly water hyacinth (Eichhornia crassipes) and some other aquatic plants like water lettuce (Pistia stratiotes), duckweed (Najas graminea), Potamogeton alpinus, Salvinia spp. etc. (Figure 13). Organic materials like paddy stubs, straw and coconut husk are also added. In perennial wetlands and permanently waterlogged areas it is possible to cultivate crops on these floating beds year round. In seasonally waterlogged areas, the beds are used during the wet season and left to decompose on the agricultural land, once the water withdraws. The floating beds are primarily constructed where water hyacinths are available. The beds can be prepared in any depth of water and they can be moved by dragging them behind a boat.
(a) Reprinted from “Local Capacity Building for Advancing Adaptation to Climate Change in Floodplains and Coastal Areas of Bangladesh” by S.M. Alauddin and Dwijen Mallick, In: South Asian Regional Workshop on Climate smart disaster risk management, June 13–16, 2010, Delhi, India. Retrieved from slide no. 42 at: http://www.slideshare.net/SCRpresentations/bcas-casescr-regional-wp-readonly. Copyright (2014) by Bangladesh Centre for Advanced Studies (BCAS). Reprinted with permission.
(b) Reprinted from “Floating vegetable cultivation in Najipur, an upazila of Pirojpur district of Bangladesh” by mahfujalam, 2011. Retrieved from http://mahfujalam.wordpress.com/2011/10/09/floating-vegetable-cultivation. Copyright (2011) by Mahfuj Alam. Reprinted with permission.
(c) Photograph shows the floating vegetable cultivation around the southern region of Bangladesh. Source: Dr. Abu Wali Raghib Hassan (personal communication).
(d) Reprinted from "Vegetables on water." In: The Daily Star by Habibur Rahman, 2013. Retrieved from http://korea-bangla.com/pages/vegetable.php or The Daily Star, Thursday, August 22, 2013. Copyright (2013) by korea-bangla.com. Reprinted with permission.
(e) Reprinted from “Community Based Adaptation (CBA)” by Dr. Atiq Rahman/Dr. Muslem Uddin Miah, 2013. Retrieved from the brochure of 7th conference on community-based adaptation to climate change (CBA7) organized by BCAS and IIED, April 18–25, 2013, Dhaka, Bangladesh. Copyright (2013) by Bangladesh Centre for Advanced Studies (BCAS). Reprinted with permission.
(f) Reprinted from "Floating Agricultural Field" by Template:Nazmulhuqrussell (Own work), 2012. Retrieved from http://commons.wikimedia.org/wiki/File%3AFloating_Agricultural_Field.JPG. Under CC-BY-3.0 (http://creativecommons.org/licenses/by/3.0), via Wikimedia Commons.
Vegetables and seedlings raised on floating beds during the wet season include ladies finger (okra), cucurbits (like cucumber, ridged gourd, bitter gourd, snake gourd etc) amaranth, red amaranth, egg plant (brinjal), pumpkin, Indian spinach, taro, wax gourd, turmeric etc. During the dry or winter season spinach, bottle gourd, yard long bean, bean, tomato, potato, cauliflower, cabbage, kohlrabi or knolkhol, turnip, radish, carrot, ginger, onion, garlic, chilli etc are grown. Some vegetables are grown on the bed all the year round, in rotation. In seasonally flooded areas, the beds are spread over the soil as the water withdraws. Winter crops can then be grown on this soil without further tillage or fertilizer 42.
A macha is an elevated arrangement constructed on floating water with bamboos and steel where creeping vegetables like country bean, gourds etc are grown (Figure 14).
Reprinted from “Floating gardens can feed Bangladesh” by Holly Holmes, 2014. Retrieved from http://www.worldfishcenter.org/featured/floating-gardens-can-feed-bangladesh#.U1NFYlPiJdg. Copyright (2014) by WorldFish. Reprinted with permission.
Sorjan is an Indonesian term referring to a cloth with colored stripes. It is a traditional technology in Java where land for cultivation is limited but the population is high. Thus the Sorjan cropping system that practiced in swampy or flooded areas is an intensive method of growing crops on alternatively raised beds and deep sinks. Farmers divide a piece of submerged land into several numbers of plots and raise one plot with the soil remaining in the adjoining plots keeping the elevation of the raised plots is two times higher than the lower one. This arrangement prevents the raised plots to be submerged by the tide, although the flow is undergone and submerged in the land between the raised plots. The raised plots are fertilized with rotten hyacinth and like others where potato, cabbage, sugarcane, arum etc are produced mostly on commercial basis (Figure 15). Sometimes machas are constructed in between the raised plots where creepers are grown.
Machas are shown in between the ridges.
Source: Dr. Abu Wali Raghib Hassan (personal communication).
Some farmers elevate and widen enough the entire periphery of their land making the shape as a pond where fish is cultivated and boundary is utilized to cultivate horticultural crops like banana, country bean etc (Figure 16). The ventures intend to utilize the waterlogged lands with maximum economic profitability and to reduce vulnerability by using sifting agriculture.
The periphery is commercially used for bean cultivation.
To improve the situation for rice production, recently the affected households have negotiated with few rich persons (locally so called Mahajan) of their locality. All the farmers who have rice land will be benefitted through draining out entire water from beels by pumping to nearest river or channels before rice (especially Boro) transplantation and respective Mahajans will be benefitted through fish cultivation in their land in the rainy season (Figure 17). With this term and conditions the farmers are getting benefit allowing their land for Boro cultivation but the ownership of the land goes to Mahajan for rest of the months of the year. All the farmers i.e. the land owners of the area come to that agreement but this sometimes creates another problem. Although they are able to produce a crop conditionally they are not agreed to continue such arrangement forever.
Many people or households altered their livelihood from rice cultivation to catching fishes together with many other flora and fauna grown in the confined waterlogged areas although the outcomes are not so great. Many people change their livelihood from agricultural labourer to some other professions like drawing rickshaw or van. In acute jobless situation, some people migrate to city for earning.
Southern region of Bangladesh would face the bad consequences of climate change where most negative impacts will be arrived than ever before due to sea-level raising which facilitates the other negative impacts like water logging. It is reported that the land of south-western coastal region is declined for many years. Before establishing the coastal embankment/polders, the rate of land formation with silt was higher than the land declination of today. So gradually the height of land was growing but after establishing embankment, the formation of land is seriously hampered. During the last 30–40 years land declines and the area within polder goes under compare to the height of river and also siltation into the river 1. Therefore many lower pockets within the polders are formed where water logging occurs today. So, these lower pockets should have to raise first thus water logging could not be perpetuated there. Elevating the roads or plinth rising is not enough measure rather entire landscapes especially beels should be raised.
The low-lying areas of southern reach especially southern parts of Khulna Division are most vulnerable to sea-level rising and water logging. Some districts of that region like Khulna, Jessore, Satkhira, Bagerhat and Narail have a combined area of 15,735 km2– the zone is on an average two meters above the sea level. According to locals and experts, the populations of those districts could adapt to rising sea levels if Tidal River Management (TRM) is practiced in scientific way 45. The TRM allows silt bearing flood tides to inundate floodplains unhindered, resulting in sedimentation of the land. Ebb tides take the water back out to the Bay remove the upper silt that deposited on the riverbeds and increase the depth of the river. This natural process of the coastal rivers has historically been welcomed by the local people. Flood or high tides raise the floodplains by new land formation through silt deposition, while ebb or low tides deepen riverbeds as outgoing water force erodes the riverbed and increase the drainage capacity. For example, the depth of the Hari River increased about 30 feet since the embankment was cut or breached by the local people in 1997 45 as they identified from their own experience and observation that the embankment is the main cause of water-logging. Their logic was that if tidal flows can be made free, the navigability of the rivers will be restored, the enclosed lands will be free from water-logging, alluvium will accumulate inside the polders, and as a result the level of land will rise 50.
The indigenous TRM technolgy raises the beel with the siltation process through utilising the ebb and flow actions of tidal river. Simply it is a siltation process as the beds of some rivers like Kobadak, Chitra, Atharobaki, Bhadra etc. are being raised. Due to so many dams and embankments, natural TRM did not function on the lower coastal region, consequently siltation occurred on the riverbeds with larger deposition. If the regions were free from the engineering intervention (i.e. polderisation) many lower pockets would have been raised enough by this time through natural siltation as was riverbed raised. It is exemplified that almost all 9 km2 of land inside Beel Bhaina has been freed from water logging through raising about a meter in a 3-year course (from 1999 to 2001) of TRM operation as per an initiative of local people as they cut the embankment to allow tidal flow inside the beel against the administrative pressure 3, 50. Another successful example is the East Beel Khukshia TRM 51. Due to operation of East Beel Khukshia TRM and dredging/excavation of critical reaches of Hari River, about 93% (17,254 ha) area has been reclaimed till early September 2011 (total water-logged area was 18,100 ha). All the homesteads, schools, colleges, roads and other infrastructures were free from water-logging problem at the end of November 2011 50.
Local inhabitants have resurrected the age-old practice of raising the land through TRM, which has freed many low-lying lands from water logging caused by polderisation during the sixties. With observing some expected practial results the Engineers of Bangladesh Water Development Board (BWDB) arranged the TRM technology with planned way and finally TRM has been accepted as a method of coastal river management in 2000 45. The BWDB authority has already started to operate TRM in some beels but the raising process is slow thus creating people’s dissatisfection as the beels are remained uncultivaed by crops during TRM operation. Some other social problems are also reported to exist aorund TRM operation 52-54. More scientific and logical TRM approcah along with proper people’s motivation and community partcipation would solve such problem substantially 55-57. The affected people would be supported by the social safety net programmes of the government during TRM operation. The regions which are being deprived since long from natural TRM, it is not impossible to wait for an another long period for their sufficient raising if the TRM starts right now. Although slow process, TRM can be considered as a promising practical tool for climate change adaptation in southwest low-lying coastal region of Bangladesh 58.
In addition to operation of TRM the dead or silted-up rivers, canals or ponds and irrigation channels can be excavated or re-excavated by operating the major workfare social safety net programmes of the government like Food-for-Work or Cash-for-Work (hence unemployment situation would greatly be minimized) and the excavated soil can be utilized for creating, maintaining or raising the rural roads, embankment and other infrastructures which are quite crucial for mitigating the flood or water logging problem. Therefore, plinth rising or elevating the roads or habitat can be considered as an immediate and short-term measure whereas raising the beels through TRM operation should be as a substantial long-term measure for coming out the southern low-lying region from inevitable effect of sea-level rising and water logging. The interventions may also be applicable to other agro-climatic regions or countries suffering from the similar problem.
Plinth rising as well as elevating the roads or habitats can be considered as an immediate and short-term measure whereas the raising of beels through Tidal River Management (TRM) operation should be as a substantial long-term measure against the inevitable effect of water logging for the southwest low-lying region of Bangladesh. Related to TRM, other programmes like river dredging or de-siltation, excavation or re-excavation of river channels or canals etc can be continued with utilizing the workfare safety net tools like Food-for-Work or Cash-for-Work. Furthermore, for utilizing the inundated land to crop production purpose, adaptation options that observed around the southern regions might properly be screened or piloted for their befitted use to climate change adaptation in water logging areas of Bangladesh.
This paper is based on a study entitled “Adapting social safety net programs to climate change shocks: issues and options for Bangladesh” 59 which was a NFPCSP’s sponsored research report conducted by Awal et al. (2013). The designation and presentation of material in this publication do not imply the expression of any opinion whatsoever on the part of FAO nor of the NFPCSP, Government of Bangladesh, EU or USAID and reflects the sole opinions and views of the author who is fully responsible for the contents, findings and recommendations of this report.
The author is gratefully acknowledged the persons and/or institutions especially Professor Ahmed A. Jamal, Managing Editor, Banglapedia, Asiatic Society of Bangladesh; Mr. Mohammad Abdul Wazed, Director General (Additional Secretary), Department of Disaster Management, Ministry of Disaster Management and Relief, Government of the People's Republic of Bangladesh; Drs. Atiq Rahman and Muslem Uddin Miah, Bangladesh Centre for Advanced Studies (BCAS); The Editor, The Daily Star, a national daily newspaper of Bangladesh; Dr. Abu Wali Raghib Hassan, Project Director, Disaster and Climate Change Risk Management in Agriculture (DCRMA) project, Dhaka; Dr. Khondker Murshed-E-Jahan, WorldFish Center, Dhaka and Mr. Mahfuj Alam, Bangladesh, have given kind permission for using their maps or images that made the article useful one.