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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.

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.

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.

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.

Kibler K.M.,International Center for Water Hazard and Risk Management under the Auspices of | Biswas R.K.,Bangladesh Water Development Board | Lucas A.M.J.,International Center for Water Hazard and Risk Management under the Auspices of | Lucas A.M.J.,Wageningen University
Water Policy | Year: 2014

Principles of equitable and reasonable use underpin international water agreements. Despite the potential for hydrologic information to enhance resilience to extreme events, comparable application of just principles to the distribution of hydrometeorological data is poorly established.Within the Ganges-Brahmaputra-Meghna (GBM) river basin, we find that water allocation agreements are codified into treaties or Memorandums of Understanding (MoUs). Analogous decisions regarding hydrometeorological data sharing are often internalized at the level of river basin organizations and are not upheld as MoUs. This institutional structure provides extremely limited data to the most downstream nation of Bangladesh. Available precipitation and discharge stations are well below the minimum densities recommended by the World Meteorological Organization. Forecasters in Bangladesh therefore contend with vast areas of geopolitically ungauged catchment, precluding the application of basin-wide modelling approaches driven by observed data. Thus, capacity for increasing resilience to extreme events within Bangladesh is obstructed, demonstrating the potential for perceived injustice related to distribution of hydrometeorological data. Consensus that water is a human right warrants the application of equity to water allocation. But is security from water-related disasters also a human right? As hydrometeorological data can be a powerful resource with potential to profoundly affect lives and livelihoods, enhanced awareness of justice related to data sharing is needed. © 2014 IWA Publishing.

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