Bangladesh Water Development Board

Motijheel, Bangladesh

Bangladesh Water Development Board

Motijheel, Bangladesh
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Banda M.S.,Leichtweiss Institute LWI | Dittrich A.,Leichtweiss Institute LWI | Pervez J.,Bangladesh Water Development Board
River Sedimentation - Proceedings of the 13th International Symposium on River Sedimentation, ISRS 2016 | Year: 2017

A 3D morphodynamic model of a meandering sand-bed river was developed using the Delft3D model package. Focus of the study was on the River Dhaleshwari, Bangladesh. The investigations focused mainly on the determination of secondary currents which are characteristic for meanders. For this purpose a boat-mounted acoustic Doppler current profiler (aDcp) at a meander bend section was used to measure the three-dimensional flow field. Model parameters were calibrated with the aDcp data for simulating primary and secondary currents. In this context the question occurred if such a calibration might lead to a good estimation of the meandering behavior of the chosen sand-bed river. To answer this question, we aimed to compare the results of one year morphodynamic computation with the field data and adopted the Brier Skill Scores (BSS) as quality parameters to assess the ability of model predictions. The model had a skill score of 0.20 and qualified as reasonable/fair according to Sutherland et al. (2004). The results of this study suggested that once properly calibrated and validated with flow measurements, the modelling approach could provide potentially a sound basis for prediction of bed level changes. © 2017 Taylor & Francis Group, London.

Oberhagemann K.,Northwest Hydraulic Consultants Ltd | Aminul Haque A.M.,Bangladesh Water Development Board
Scour and Erosion - Proceedings of the 8th International Conference on Scour and Erosion, ICSE 2016 | Year: 2016

Over the last two decades the Bangladesh Water Development Board (BWDB) has developed the widely accepted riverbank protection technology of geotextile bag revetments, consisting of multiple layers of systematically dumped geobags below low water plus a single layer of concrete blocks above low water. The original design characteristics from the early 2000s have proven sufficient for the most common application alongside largely agricultural land, with emphasis on the dimensions of the toe apron. In case of more severe design requirements, geotextile bags have been used as filter layer covered with rock. By and large geotextile bag revetments have become the backbone for a more stabilized Brahmaputra River System with a narrowed river corridor. © 2016 Taylor & Francis Group, London.

Ravenscroft P.,Independent Consultant | Mahmud Z.H.,International Center for Diarrhoeal Disease Research | Islam M.S.,International Center for Diarrhoeal Disease Research | Hossain A.K.M.Z.,International Center for Diarrhoeal Disease Research | And 6 more authors.
Water Research | Year: 2017

Faecal contamination of groundwater from pit latrines is widely perceived as a major threat to the safety of drinking water for several billion people in rural and peri-urban areas worldwide. On the floodplains of the Ganges-Brahmaputra-Meghna delta in Bangladesh, we constructed latrines and monitored piezometer nests monthly for two years. We detected faecal coliforms (FC) in 3.3–23.3% of samples at four sites. We differentiate a near-field, characterised by high concentrations and frequent, persistent and contiguous contamination in all directions, and a far-field characterised by rare, impersistent, discontinuous low-level detections in variable directions. Far-field FC concentrations at four sites exceeded 0 and 10 cfu/100 ml in 2.4–9.6% and 0.2–2.3% of sampling events respectively. The lesser contamination of in-situ groundwater compared to water at the point-of-collection from domestic wells, which itself is less contaminated than at the point-of-consumption, demonstrates the importance of recontamination in the well-pump system. We present a conceptual model comprising four sub-pathways: the latrine-aquifer interface (near-field); groundwater flowing from latrine to well (far-field); the well-pump system; and post-collection handling and storage. Applying a hypothetical dose-response model suggests that 1–2% of the diarrhoeal disease burden from drinking water is derived from the aquifer, 29% from the well-pump system, and 70% from post-collection handling. The important implications are (i) that leakage from pit latrines is a minor contributor to faecal contamination of drinking water in alluvial-deltaic terrains; (ii) fears of increased groundwater pollution should not constrain expanding latrine coverage, and (iii) that more attention should be given to reducing contamination around the well-head. © 2017 Elsevier Ltd

Rahman M.M.,Bangladesh Water Development Board | Arya D.S.,Indian Institute of Technology Roorkee | Goel N.K.,Indian Institute of Technology Roorkee | Dhamy A.P.,Ministry of Water Resources
Journal of Hydrologic Engineering | Year: 2010

A case study was conducted in the Teesta subcatchment in Bangladesh for determining design flood flows and corresponding flood stages for different return periods using frequency analysis and MIKE 11 model. Different distribution functions of frequency analysis were tested for their goodness of fit. The observed discharge data at Kaunia on the river Teesta were used for estimation of design flood. The Pearson type-III distribution was found best fitted by the Kolmogorov-Smirnov, D-index, and L-moment diagram ratio tests, and accordingly 25-, 50-, and 100-year return period design floods were computed. The river network of Teesta River was extracted from SRTM 90-m digital elevation model. The river network of Teesta subcatchment was then simulated by MIKE 11 rainfall-runoff Nedbor-Afstromnings-Model (NAM) and HD model. The resultant time series of river stage was then compared with corresponding observed values. From the model, a stage-discharge relationship (Q-h) curve and respective equation were developed for Kaunia station on the river Teesta. The developed equation determines the corresponding flood stage of estimated flood flow of 25-, 50-, and 100-year return periods. The resulting flows and stages will be useful to design hydraulic structures, prepare flood extent maps, assess vulnerability of flood damage for different return periods, and provide flood forecasting for early warnings of floods. The approach presented would be applicable to similar river basin systems where data are limited and scarce. © 2011 ASCE.

Steckler M.S.,Lamont Doherty Earth Observatory | Nooner S.L.,Lamont Doherty Earth Observatory | Akhter S.H.,University of Dhaka | Chowdhury S.K.,Bangladesh Water Development Board | And 3 more authors.
Journal of Geophysical Research: Solid Earth | Year: 2010

The Ganges, Brahmaputra, and Meghna rivers converge in Bangladesh with an annual discharge second to the Amazon. Most of the flow occurs during the summer monsoon causing widespread flooding. The impounded water represents a large surface load whose effects can be observed in Gravity Recovery and Climate Experiment (GRACE) and GPS data. Bangladesh is at the center of the second largest seasonal anomaly in the GRACE gravity field, reflecting water storage in Southeast Asia. Eighteen continuous GPS stations in Bangladesh record seasonal vertical motions up to 6 cm that inversely correlate to river level. We use 304 river gages to compute water height surfaces with a digital elevation model to separate surface water from groundwater. Porosity of 20% was used to estimate groundwater mass and calculate the water load. Results show ∼100 GT of water are stored in Bangladesh (7.5% of annual discharge) but can reach 150 GT during extreme events. The calculated water mass agrees with monthly GRACE water mass equivalents from Bangladesh within statistical limits. We compute the deformation due to this water load on an elastic half-space, and we vary Young's modulus to fit GPS data from our two most continuous records. The water loading can account for >50% of the variance in the GPS data. The best fitting Young's modulus is 117-124 GPa for DHAK and 133-135 GPa for SUST, although the upper bound is not well constrained. These estimates lie between sediment (30-75 GPa) and mantle (190 GPa) values, indicating that response to loading is sensitive to structure throughout the lithosphere and is not absorbed by the weak sediments. Copyright © 2010 by the American Geophysical Union.

Rahman M.M.,Bangladesh Water Development Board | Goel N.K.,Indian Institute of Technology Roorkee | Arya D.S.,Indian Institute of Technology Roorkee
Journal of Hydrologic Engineering | Year: 2012

A flood forecasting system has been developed using MIKE11 river-modeling software modules rainfall-runoff (RR) [or Nedbor-Afstromnings model (NAM)], hydrodynamic (HD), and flood forecasting (FF) for the Jamuneswari river catchment of the northwestern part of Bangladesh. The 3-arc second shuttle radar topography mission (SRTM) digital elevation model (DEM) version 4.0 and the D8 method of ArcGIS9.3 have been used to delineate river network and catchment bounderies, which are required for MIKE 11 model setup. The European Centre for Medium-Range Weather Forecast (ECMWF) model-forecasted rainfall data have been used in MIKE 11 NAM-HD modules to increase the forecast lead time to 72 h. Errors in forecast results have been assessed by computing efficiency index, coefficient of correlation, volume error, peak error, and peak time error. Integration of the MIKE 11 HD module with the MIKE NAM module has improved the result by 10.84% for efficiency index, 20.7% for volume error, 25.61% for peak error, and 95.83% for peak time error. The MIKE 11 FF module was applied along with the integrated MIKE 11 NAM and HD modules to minimize error in the forecasted result. The efficiency index, volume error, peak error, and peak time error of the hindcast result, before updating by MIKE 11 FF, were calculated as 0.803, 0.505%, 2.58%, and 2 h, After updating by the MIKE 11 FF module, results were calculated as 0.989, -0.005%, 0.158%, and 0.00 h. Inputting the ECMWF-forecasted rainfall, the updated forecasting system determined the efficiency index, volume error, peak error, and peak time error as 0.92, 0.008%, 0.87%, and 0.00% for 24 h; 0.87, 0.231%, 0.507%, and 0.00 h for 48 h; and 0.84, 0.519%, and 0.000 h for 72 h. The steps for developing the flood forecasting system described in this case study are generic and can be applied under similar geographic conditions in other locations worldwide. In Bangladesh, decision makers will have more time to develop responses to imminent the flooding as a result of the increased forecast lead time provided by the analysis method described in this case study. © 2012 American Society of Civil Engineers.

Oberhagemann K.,Northwest Hydraulic Consultants Inc. | Hossain M.M.,Bangladesh Water Development Board
Geotextiles and Geomembranes | Year: 2011

Since the late 1990s, riverbank revetments constructed of sand-filled geotextile bags (geotextile bags) have been developed in Bangladesh in response to the lack of traditional erosion-protection materials, particularly rock. After independence in 1971 and the related loss of access to quarries, rock was replaced by concrete cubes, but those are expensive and slow to manufacture. Geotextile bags on the other hand, first used as emergency measures during the second half of the 1990s, can be filled with local sand and therefore provide the opportunity to respond quickly to dynamic river changes. Geotextile bags also provide the potential for substantial cost reduction, due to the use of locally available resources. The use of the abundant local sand reduces transport distance and cost, while local labor is used for filling, transporting, and dumping of the 75-250. kg bags. Driven by the need for longer protection, the idea of using geotextile bags for permanent riverbank protection emerged in 2001. Eight years of experience have enabled systematic placement of geotextile bag protection along about 12. km of major riverbanks at a unit cost of around USD 2. M per km. By comparison, concrete-block revetments cost around USD 5. M per km. In addition, there are strong indications that geotextile bags perform better than concrete blocks as underwater protection, largely due to their inherent filter properties and better launching behavior when the toe of the protected underwater slope is under-scoured. This article reports the outcome of the last eight years of development work under the ADB-supported Jamuna-Meghna River Erosion Mitigation Project (ADB, 2002), implemented by the Bangladesh Water Development Board. Besides substituting geotextile bags for concrete blocks as protective elements, the project involved development of a comprehensive planning system to improve the overall reliability and sustainability of riverbank protection works. © 2010 Elsevier Ltd.

Bhattacharya B.,UNESCO-IHE Institute for Water Education | Shams M.S.,Bangladesh Water Development Board | Popescu I.,UNESCO-IHE Institute for Water Education
Environmental Engineering and Management Journal | Year: 2013

Flood inundation modelling and flood risk mapping are primary cornerstones of flood risk assessment and management. Modelling activities generally assume that the morphology of the conveyance does not change, which certainly is not true for alluvial rivers. River bed elevations can quickly change during flood events. Flood water can induce different bed-forms (ripples, dunes, plain bed, etc.), which affects the flow resistance and as a result the flood water level. As a result integrating the river bed dynamics in flood risk management has the benefit of providing more realistic representation of flood levels. The paper presents an analysis of a measured dataset of River Rhine in the Netherlands to show the variation of dune heights during a flood in 2004. In another case study a hydraulic model, capable of simulating the changes in bed forms and the corresponding friction, has been developed for the Nzoia River in Kenya. This case study as well shows the development of dunes with flood and the corresponding effects on roughness and flood water level. Both case studies substantiate the importance of incorporating the changes in bed resistance due to the formation of bed forms in flood inundation modelling.

Shamsudduha M.,University College London | Taylor R.G.,University College London | Ahmed K.M.,University of Dhaka | Zahid A.,Bangladesh Water Development Board
Hydrogeology Journal | Year: 2011

Quantitative evaluations of the impact of groundwater abstraction on recharge are rare. Over a period (1975-2007) during which groundwater abstraction increased dramatically in the Bengal Basin, changes in net groundwater recharge in Bangladesh are assessed using the water-table fluctuation method. Mean annual groundwater recharge is shown to be higher (300-600 mm) in northwestern and southwestern areas of Bangladesh than in southeastern and northeastern regions (< 100 mm) where rainfall and potential recharge are greater. Net recharge in many parts of Bangladesh has increased substantially (5-15 mm/year between 1985 and 2007) in response to increased groundwater abstraction for irrigation and urban water supplies. In contrast, net recharge has slightly decreased (-0.5 to -1 mm/year) in areas where groundwater-fed irrigation is low (< 30% of total irrigation) and where abstraction has either decreased or remained unchanged over the period of 1985-2007. The spatio-temporal dynamics of recharge in Bangladesh illustrate the fundamental flaw in definitions of "safe yield" based on recharge estimated under static (non-pumping) conditions and reveal the areas where (1) further groundwater abstraction may increase actual recharge to the shallow aquifer, and (2) current groundwater abstraction for irrigation and urban water supplies is unsustainable. © 2011 Springer-Verlag.

Rahman M.M.,Bangladesh Water Development Board | Arya D.S.,Indian Institute of Technology Roorkee | Goel N.K.,Indian Institute of Technology Roorkee
Applied Geomatics | Year: 2010

Bangladesh is the deltaic flood plain located in the lower ridge of the Ganges Brahmaputra and Meghna basins. The country is very flat having 40% of its landmass up to 10 m above the mean sea level. Shuttle Radar Topography Mission (SRTM) 90 m, i.e., 3-arc second digital elevation model (DEM) is being widely used to delineate river network and to extract catchment information using hydrology tool of ArcGIS. The hydrology tool uses the D8 method for extraction of drainage pattern. The study was carried out to find the limitation and suitability of 90 m SRTM DEM data in flat terrains especially in Bangladesh using ArcGIS. Twelve catchments of varying geomorphology were chosen from five hydrological zones of Bangladesh. Basin characteristics such as bifurcation ratio, drainage density, and channel slope of the catchments were estimated and analyzed to evaluate the suitability of 90 m SRTM DEM. The delineated catchments of slope 1:3,600 or more flat shows large deviation in river network alignment when compared with the digital river network developed by Bangladesh Water Development Board and with Google Earth's images. The catchments having slope 1:2,850 and more steep were delineated correctly. The conclusion could not be established between slopes 1:2,850 and 1:3,600. The study also revealed that the catchment characteristics other than the slope have no effect on river network delineation © The Author(s) 2010.

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