Dissertations/Theses - Department of Water Resources Engineering

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A Study of bankline shifting of the selected reach of Jamuna river left bank using numerical models
(Department of Water Resources Engineering (WRE), 2023-01-09) HAQUE, AKRAMUL; Matin, Dr. Md. Abdul
The present study deals with the development of a computational procedure to predict the morphological behavior of the Jamunariver such as bed level changesand bankline shifting. A reach of 80 kms long left bank of the Jamuna river from Bahadurabad to Sirajganjwas selected for thisstudy .Numerical models named RIVERFLOW 2D, HEC-RAS 1D and multi-variate regression modeling tools have been used. This study also proposes a machine learning technique for the prediction of bank line shifting of river Jamuna based on the results of numerical models.Accordingly, models have been set for the hydro-morphological computation.RIVERFLOW 2D hydro-morphological model has been used for the assessment of erosion-deposition and bed level changes. This model wascalibrated utilizing the water level data collected from BWDB for the year 2018 and then validated for the year 2019. For calibration and validation, the R2 was found to be about 0.86 and 0.93 respectively. In addition, the HEC-RAS 1D hydrodynamic model has been setup, calibrated and validated using the same data. In broad category, two Scenarios have been carried outin the present computational procedure. These are Scenarioi) use of the output of HEC-RAS 1D and regression tools and Scenarioii) use of results of HEC-RAS 2D and regression tools.In Scenario-i, five variables such as maximum velocity, maximum water level, maximum left over bank discharge, maximum slope and minimum waterlevel were taken from the validated 1D hydro-dynamic model.Performance of the prediction of bankline shifting obtained from the computation have been evaluated using statistical parameters, such as RMSE, R2, MSE, and MAE. These performance evaluation have also been carried outfor various types of regression models such as linear regression, tree type regression, boosted, Gaussian, and SVM type regression models. Performance evaluation showed that that the Boosted regression model outperforms the others. For the boosted regression model, the values of RMSE, R2, MSE, and MAE were 25, 0.80, 700, and 10 respectively. On the other hand, in the Scenario- ii, use of results of HEC-RAS 2D and regression tools, three variables such as the minimum water depth, maximum water depth and maximum velocity have been extracted for the purpose of various regression models run. It is found that theprediction of bankline shifting obtained from calibrated and validated boosted regression model performed satisfactorily in whichfor the calibration, the RMSE, R2, MSE, and MAE values were found 38, 0.60, 1444, and 13 respectively. Computational performance of all the models used in the study has also been assessed in terms of discrepancy ratio. Assessment of bed level changes in terms of net erosion and deposition has been analyzed using RIVER FLOW 2D.Model results showed thatmaximum erosion was 17.7 m/year and maximum depositions have been found 7.3 m/year near Bhuapur hard point area.In order to verify the efficacy of prediction of bank lineerosion, Jamuna river left bank data from Google satellite images for the year 2018-2021were also compared.It is found that boosted regression model performed better when compared with others regression models.Based on the statistical parameters (RMSE, MSE, R2, MAE) and discrepancy ratio,Scenario one (HECRAS 1D and regression model) performed comparatively better (RMSE=56, MSE=3200, R2=0.60, MAE=23). On the other hand, Scenariotwo (HECRAS 2D and regression model) performed relatively better (RMSE=50, MSE=2500, R2=0.65, MAE=20) than that of Scenario one. It is hoped that computational procedure suggested in this study based on river models and multi-variate regression tools can be helpful for the analysis of river bank shifting of alluvial rivers.
A Study on Fluvial Flood Hazard and Risk Assessment of Arial Khan River Floodplain under Future Climate Change Scenarios
(Department of Water Resources Engineering, 2019-01-14) Roy, Binata; Khan, Dr. Md. Sabbir Mostafa
Bangladesh is highly susceptible to flood due to its location at the confluence of the world’s three major basins– Ganges-Brahmaputra-Meghna (GBM) and hydro-meteorological and topographical characteristics of the basins. Increase in temperature and precipitation due to climate change will significantly increase the monsoon flow of the GBM rivers which may lead to more intense and frequent floods in Bangladesh in upcoming decades. In this study, the fluvial flood hazard and risk of Arial Khan River floodplain have been assessed for the predicted climate change scenarios of RCP 2.6 and RCP 8.5. A calibrated and validated SWAT model of GBM basins has been used to project the future flow magnitudes at Bahadurabad Transit (Brahmaputra River) and Hardinge Bridge (Ganges River) for RCP 2.6 and 8.5 scenarios. Using the flow magnitude of these stations as the upstream boundaries, a 1D HEC-RAS model has been set up for the Brahmaputra-Ganges-Padma River for generating future flow magnitude at Mawa of Padma River. Later, the discharge at the offtake of Arial Khan has been calculated establishing a linear regression equation between the Arial Khan and Padma River. Finally, a 1D-2D coupled model of Arial Khan River floodplain has been set up in HEC-RAS. This coupled model is calibrated and validated for Manning's roughness coefficient ‘n’ = 0.015-0.02 for the year of 2015 and 2017 respectively. After calibration and validation, the model is simulated for different periods of RCP 2.6 and RCP 8.5 scenarios: baseline (1976-2005), 2020s (2006-2035), 2050s (2036-2065) and 2080s (2066-2095). The model result shows that the total flood affected area is nearly 15% at the base condition which is increased to 30% and 47% approximately for the 2080s of RCP 2.6 and RCP 8.5 respectively. The hazard assessment reveals that at the base condition, 48%, 34% and 18% area are in the very low, low and high hazard zone respectively. It is increased to manifolds such as 21%, 27%, 34% and 18% in the very low, low, medium and very hazard zone respectively for the 2080s of RCP 2.6 and it became 22%, 26%, 34% and 18% in the low, medium, high and very high hazard zone respectively for the 2080s of RCP 8.5. Similar to hazard, risk assessment also shows that the very low and low risk zone will decrease and high and very high risk zone will increase significantly by the end of 21st century compared to the base period. Incorporation of vulnerability and exposure gives a complete different horizon to the overall assessment. It is found that some medium hazard zones have a high risk of flood damage due to its high exposure and vulnerability to flood while some high hazard zone falls into the low risk zone because of its low exposure and vulnerability. The overall flood assessment for different projections of RCP 2.6 and RCP 8.5 show that there is an increasing trend of the flood from baseline to 2080s, both for RCP 2.6 and RCP 8.5. From baseline to 2050s, the difference between RCP 2.6 and RCP 8.5 is slight. However, this variation becomes very drastic after the 2050s. The inundation pattern, hazard and risk extent increase manifolds in the 2080s of RCP 8.5 than those of RCP 2.6. So future climate change is going to have a terrible effect on the flood situation of Arial Khan River floodplain. The results found in this study provide useful information on projected changes of flood hazard and risk in the Arial Khan River floodplain over the next decades to a century. Additionally, this study will act as a guideline regarding how to incorporate the globalize climate change scenarios of a large basin to a small local river and its floodplain and find out localized flood hazard and risk maps under climate change scenarios.
Analysis of rainfall characteristics of northeast region of Bangladesh
(Department of Water Resources Engineering, 1987-10) Abdur Rauf, Md.; Bari, Dr. M Fazlul
The aim of this study is to summarise the changing behaviour of rainfall in space and time over the northeast region of Bangladesh. During the study various rainfall parameters were investigated and mathematical relationships were established. Updated isohyetal maps of mean monthly, monsoon (June-September) and annual rainfall were constructed for the study region. Spatial distribution of mean monthly, monsoon and annual number of rainy days were investigated. Normal monsoon rainfall of selected 32 stations within the region have been estimated and normal annual rainfall chart has been updated. Temporal variability of rainfall and number of rainy days over the region has been investigated. Moving average and percent departure of rainfall for every year with reference to the normal rainfall were worked out for this purpose. Attempts were made to establish mathematical relationships between number of rainy days and monsoon rainfall total and between mean daily rainfall intensity and monsoon rainfall total. Various forms of equations were examined. Analytical probability distributions were fitted to 1-, 2-, 3-, 5-, 7- and lO-day maximum rainfall values. Normal, lognormal and Gumbel (EV1) distributions were examined and all of them were found good for maximum rainfall values. Gumbel distribution was found to be better. Pattern of Gumbel parameters over the region for 1-, 3-, 5- and 7-day maximum rainfall were presented on the base maps. Binomial and Poisson discrete probability models were tested to monsoon and annual number of rainy days. Normal approximation to Poisson distribution was found suitable to describe monsoon and annual number of rainy days. HYMOS (HYdrological MOdelling System), developed at Delft Hydraulics, the Netherlands, has been extensively used for probability distribution and other analysis in performing the study.
Analysis of rainfall data for estimating the intensity duration-frequency relationship for the north-eastern region of Bangladesh
(Department of Water Resources Engineering, 1984-07) Md. Abdul Matin; Mohib Uddin Ahmed, Dr. Syed
For abstract please see full text
Analysis of stormwater runoff for a selected catchment of eastern Dhaka using hydrologic model
(Department of Water Resources Engineering, 2018-03-21) Ahammad, Munee; Khan, Dr. Md. Sabbir Mostafa
Dhaka, the capital of Bangladesh and one of the world’s rapidly growing megacities, faces the recurring phenomena of urban flooding and waterlogging following intense rainfall nearly every year. The water level of the Brahmaputra and rainfall and runoff from the entire Brahmaputra Basin mainly influence the process of river floods in and around the city. Dhaka’s average annual rainfall is about 2,000 mm, most of it occurring during the summer monsoon. As a low-elevation city with a tropical monsoon climate, Dhaka has a long history of river flooding as a natural hazard. A growing concern is that, in a changing climate, characterized by heavier and more erratic rainfall in the Ganges-Brahmaputra-Meghna (GBM) Basin during the monsoon season, the situation may worsen. Thus, stormwater management is a challenging task in such densely populated urban area having weak water governance and a lack in the institutional arrangement. It is even more challenging as the natural drainage system experiences relatively high water levels in the peripheral rivers during the rainy season, and the system capacity is compromised due to encroachment of the runoff detention areas. At present, only the western part of Dhaka is protected against river floods of Turag, Buriganga, and Balu rivers. The problem of eastern side of the city covers both the external river flood and internal flood from stormwater. An embankment along the right bank of Balu River can protect the Eastern Dhaka from river flood, and then the internal stormwater can be discharged into the river with a number of drainage pumps. Against this backdrop, this study focuses on the stormwater management of Begunabari canal catchment, the largest catchment of Eastern Dhaka. The general physical setting for the study is 47.67 km2 area, which has been modeled in GeoSWMM. The specific objectives of this study include proper calibration of the model, and then its application for future drainage improvements and adaptation measures considering future landuse and climate change impact. In this study, the model is calibrated with observed water level data at Begunbari canal, Banasree and then drainage facilities have been designed for 2 day 10 year return period. The design rainfall value of 286 mm is increased by 16% considering the climate effects of A1FI 2050 scenario. The study’s key findings highlight the required pumping capacities and retention facilities after implementation of Eastern Embankment. While finding this requirement, future landuse suggested by RDP, 2035 is considered along with stated climate change effect. The suggested pumping station at Begunbari canal outlet would drain out 50 cumec stormwater to maintain internal water level not to exceed 4.5m PWD at times of design storm evacuating the excess flooding within 2 days. To do such it will require 1.5 sq. km of retention pond at the pumping station. The bottom level of retention pond is considered at -0.5 mPWD while pump start level at 3.3m PWD in the monsoon. Regulators would be functional during pre-monsoon and post monsoon period when Balu is at lower level allowing gravity drainage. Here, the designed pump has been applied for 2day rainfall of 5, 10 and 25 years return period. It was observed that the inundated area with depth greater than 1.5 m can be reduced by 15-30%, while the total inundated area can be reduced by 18-25% by pumping. The study also explored the scope of flood reduction by storage tanks of rainwater harvesting system. There are 13 subcatchments identified where future development would occur. 30% of this future development area is considered here as rooftop area and the storage tanks are designed accordingly. The design values of storage volumes are taken from an implemented project in Gujarat, India. Total 6475 m2 storage area is considered taking the depth of tank as 10 m. The inundation depth and area both were found reduced in this case by taking measures of pumping with storage tank for rainwater harvesting. For 2 days rainfall, the area with depth greater than 1.5 m can be reduced by around 87%, while the total inundated area can be reduced by around 60% by storage tank along with the pumping. Again, the stored water can be used for household purpose and even for groundwater recharge. So, this option should be considered during future development in this area.
Analysis of the beach materials at the Kuakata coast
(Department of Water Resources Engineering, 1999-10) Matiur Rahman, Md.; Alam, Dr. Md. Khorshed
For abstract please see full text
Applicability of alluvial roughness predictors for ganges river
(Department of Water Resources Engineering, 1998-04) Shafiul Alam, Md.; Halim, Dr. M. A.
For abstract please see full text
Applicability of alluvial roughness predictors for Gumti, Kushiyara and Mohananda rivers
(Department of Water Resources Engineering, 1999-12) Jalal Uddin, Md.; Halim, Dr. M. A.
This study has been performed to determine the applicability of alluvial roughness predictors for Gumti, Kushiyara and Mohananda rivers. Eleven roughness predictors are evaluated- six are based on division of roughness and five are based on overall roughness. The selected methods are evaluated on the basis of Manning's n, Chezy's C and Darcy-Weisbach friction factor f and, where possible, on the basis of depth and/or velocity. To predict the roughness characteristics of alluvial rivers, hydrological data, e.g. discharge, cross-sectional area, mean velocity, river width, water surface slope and grain size data of bed materials are needed. The discharge stations Jibanpur, Sherpur and Chapai Nawabganj are selected for the rivers Gumti, Kushiyara and Mohananda, respectively. The required hydrological and grain size data of the selected rivers have been obtained from BWDB and SWMC, respectively. The Manning, Chezy and Darcy-Weisbach formulae are applied to calculate the roughness coefficients n, C and f, respectively. The roughness coefficients are also predicted by using the selected roughness predictors and then these values were compared with the values obtained by Manning, Chezy and Darcy-Weisbach formulae. Accuracy of different predictors has been determined on the basis of MNE and the standard deviation ofthe MNE. Out of the eleven selected roughness predictors, the Einstein and Barbarossa (1952) is the only method, which can satisfactorily predict roughness coefficients for full range of discharges for all the rivers. Some of the roughness predictors seem to predict Manning's n satisfactorily for the full range of discharge of a particular river, e.g. the Shen (1962) method for Gumti river. Shen (1962) method for the Kushiyara river predicts Manning's n about 100% higher than the calculated values for all discharges. Simons' and Richardson (1966) method predicts Manning's n about 48% higher for the Gumti river and 87% higher for the Kushiyara river than the calculated values for all discharges. Some methods predict Manning's n satisfactorily only for moderate to high range of discharge of a particular river, e.g. Haque and Mahmood (1983) and Shen et al. (1990) methods for the Kushiyara river. Some of the methods, e.g. Engelund and Hansen (1967), Van Rijn (1993), Garde and Ranga Raju (1977), Brownlie (1983), White et al. (1987) and Karim (1995) methods predict roughness coefficients of poor quality for any discharges and all the rivers. The Einstein and Barbarossa (1952), Shen (1962) and Brownlie (1983) methods for the river Gumti and Brownlie (1983) and Karim (1995) methods for the river Kushiyara predict depth satisfactorily. During analyses of the hydrological data collected from BWDB for the river Mohananda, the data did not seem reliable, because the calculated Manning's n from observed data vary from 2.316 to 0.081 which are about 30 to 3 times higher than from its normal ranges. So no conclusion could be drawn for the predictors in case of the Mohananda river. But Einstein and Barbarossa (1952) and Shen (1962) methods seem to predict resonable roughness coefficients for the full range of discharges and Haque and Mahmood (1983) method seems to predict resonable results for moderate to high discharges of the Mohananda river. The Manning's n for the Gumti and the Kushiyara rivers is ma.ximum when the discharge is low and decreases with increasing discharge. For the river Gumti detail analyses indicate the presence of bed forms in all discharges, i.e. throughout the year. For the river Kushiyara; bed forms are only present in the range of low to medium discharges but at high discharges the river bed becomes plane. The response of grain roughness to the change in discharge is relatively less than that for form roughness. The variation of grain roughness is responsive to that of the total roughness but the variation of form roughness is similar to the total roughness. The Manning's n for the river Gumti is maximum during the month of March when discharge is low; and attains minimum value during the months of May to October when high flow takes place. The Manning's n for the river Kushiyara is maximum during the month of February when the discharge is low and minimum during the month of July to September when the discharge is high. The Mohananda river attains the maximum discharge in the month of September and the minimum discharges in the months of December to May.
Application of 2D Mathematical Model for Verification of Water Velocity at Coastal Area of Bangladesh
(Department of Water Resources Engineering, 2012-01) Delwar Hossain, Md.; Navera, Dr. Umme Kulsum
The coastal areas of Bangladesh are different from the rest of the country due to its unique geo-physical characteristics and vulnerability to several natural disasters like cyclones with associated storm surges, erosion and accretion. Natural hazards are increasing with high frequency and intensity along the coast of Bangladesh with the changes of global climate. These extreme natural events are termed disasters when they adversely affect the whole environment including the human beings, their shelters or the resources essential for their livelihoods. Water movement in the coastal zone of Bangladesh is determined by the influences of fresh water flow from the rivers, tide coming from the Bay of Bengal, and meteorological conditions (low pressure systems, wind, storms and cyclones). A mathematical model study has been carried out to simulate the tidal flow velocity in the near shore coastline of Bangladesh. In this study a two dimensional hydrodynamic model DIVAST (Depth Integrated Velocity and Solute Transport) has been used considering the different parameters like co-efficient of eddy viscosity, Manning roughness, advective and diffusion co-efficient etc. of the Bay of Bengal. The DIVAST model is based on FORTRAN PROGRAMING and it has a number of modules for different purposes with different sets of equations. In this study hydrodynamic module has been used. The hydrodynamics of the selected area of the Bay of Bengal has been simulated by solving two-dimensional depth integrated momentum and continuity equations numerically with finite difference method. Consequently the water elevation η with respect to mean sea level and the respective velocity components U, V in the x and y directions are calculated across the selected coastal domain for a prescribed set of initial and boundary conditions. Simulated velocity has been verified at selected locations of coastal area with the measured field data and compared with the other study carried out in the coastal region of Bangladesh. Viewing over the DIVAST simulated results very good agreement is found between the measured data as well as to the other study. This encouraging good result justifies that the DIVAST model works reasonably well for the selected domain of the Bay of Bengal.
Application of a linear mathematical model to maximize the total command area and yield of Teesta barrage project
(Department of Water Resources Engineering, 1988-06) Abdur Rahman Akhanda, Md.; Saleh, Dr. A.F.M.
For abstract please see full text
Application of maccormack scheme to the study of aggradation-degradation in alluvial channels
(Department of Water Resources Engineering, 1998-07) Mahbub Alam, Md.; Bhuiyan, Dr. Muhammed Ali
Aggradation and degradation are ubiquitous phenomena that occur in most alluvial channels. The complete Saint Venant equations describe the unsteady open channel /low conditions. The continuity equation for the conservation of sediment mass needs to be solved along with the hydrodynamic equations to determine aggradation and/or degradation of channel bottom. In these viewpoints, a one-dimensional mathematical model has been developed that computes the aggradation-degradation of channel bed. The MacCormack explicit finite difference scheme has been used in the model. This scheme is second-order accurate, handles shocks and discontinuities in the solution without any special treatment, and allows simultaneous solution of the water and sediment equations, thereby obviating the need for iterations. The developed model has been applied to two different case studies. The first case is a laboratory investigation where experimental results were obtained due to imposing extra sediment load. The sediment overloading produces aggradation in the channel. It has been found that the model simulates most of the test runs with a reasonable accuracy. In order to verify the ability of the model to real field situation, it has been applied to simulate Jamuna river reach from Bahadurabad to Sirajgang. A test run for three years has been done using field data for that period. The agreement between the computed results and measured data is quite satisfactory. The successful application of the model strongly demonstrates that the model is valid in solving unsteady open channel flow problems in conjunction with sediment transport. The different problems just require incorporating the appropriate initial and boundary conditions .
Applications of palmer method in analyzing drought in northwest region of Bangladesh
(Department of Water Resources Engineering, 2005-06) Datta, Arpana Rani; Bhuiyan, Dr. Muhammed Ali
In the present study, an attempt has been made for applying the Palmcr mcthod in drought analysis in the Northwest (NW) region of Bangladesh. Palmer Drought Severity Index CPOSI) actually uses a supply and dcmand model for the amount of moisture in the soil. The method defined drought period as an interval of timc during which the actual moisture supply at a givcn place falls short of the climatically expected or appropriate moisturc supply. In the study the PDSI was calculated on monthly basis as per original formulation by Palmer, though a shorter timescale is more appropriate for irrigation scheduling in Bangladcsh. The drought analysis by the method showed that all of the stations of NW region experienced some degrees of drought conditions. The method quantified the average occurrence of drought in the region in 34 percent of the study time from 1972 to 2002. The available literature shows that thc average occurrence of drought is once in 2.5 years. The method identified the most common drought occurrences in years like 1972.73, 1975.76, 1976.77, 1978.79, 1979.80, 1982-83, 1992.93, 1994.95, 1999 and 2001.2002 in selected fifteen stations in the region. Thus the method could identitY the historical drought occurrences of Bangladesh like the year 1975, 1979, 1981.82, 1984, 1989, 1992.93 and 1994.95. The occurrences of extreme drought conditions were observed only in 3.6 percent of total time. In the study, thc Palmer method has identified the month of October rather than November or December as thc beginning of highest percentage of drought spells in the region. The method could identify Kharif droughts during the period from June/July to October. The method has identified the month of April rather than Mayor June as the ending of highest percentage of drought spells in the region. The suitability of the application of the Palmer method as a drought analyzing tool in NW region of Bangladesh has been assessed in the study by comparing the results of this method with those obtained from two other methods: i) the Standard Precipitation Index (SPl) method and ii) the Herbst method. The comparison was made in terms of several drought features such as the onset and termination of drought, duration and severity. The SPI is a standardized transform of the probability of the observed precipitation. The method used half-monthly observed rainfall data to analyze drought on the monthly time scale. The Herbst method quantified droughts on a half-monthly time scale using different drought parameters such as mean half-monthly rainfall, weighting factors, carryover, mean half monthly deficit etc. The method has no drought severity scale rather provides relative measures of droughts. The average occurrence of drought was in 22.3 percent and 22 percent of study time in the SPI and the Herbst methods respectively. These two methods have also identified the same drought years in NW region as in the Palmer method in the present study. The highest percentage of beginning of drought spells occur in the months of March and November respectively in the SPI and Herbst methods while the highest percentage of ending of drought spell occurs in the month of April in the SPI method and in MaylJune in the Herbst method. While applying Palmer method in drought analysis of NW region of Bangladesh, some limitations were noticed in addition to those already identified by many researchers. Despite these limitations, thc performance of the method in comparison with the SPI and Herbst methods seems realistic in NW region of Bangladesh in tenns of drought occurrences and severity. But a more detailed study is recommended for quantitative assessment of the influence of soil moisture on drought occurrences in Bangladesh. The Palmer method can be used extensively for monitoring drought conditions and for making operational water management decisions in Bangladesh after some modifications to the method.
Assesment of irrigation water requirement of maize crop
(Department of Water Resources Engineering, 2011-12) Md. Golam Ambia Mahmud; Navera, Dr. Umme Kulsum
Water is one of the most important natural resources. The rationale use of this valuable resource is a dire need at present days because the useable water resource is diminishing very rapidly. Thousand of rivers are flowing through Bangladesh. The agriculture, transportation and economy of this country depends on these rivers. Irrigation for agriculture of this country mostly depends on surface and ground water. Bangladesh being a lower riparian country and the adverse effect of climate changes create less flow of these rivers. The less or no flow of these rivers resulting in shortage of irrigation water for agricultural production and these create a dire problem in agriculture sector for irrigation water in dry season of Bangladesh. A study was conducted during the dry season (Rabi) in 2010-11 at Bangladesh Agricultural Research Institute (BARI), Joydebpur, Gazipur, to assess the irrigation water requirement of maize crop and to observe the impact of tillage methods on water use and maize yield. The effect of irrigation water on maize yield and to measure the impact of tillage practices on the surrounding environment was the other observatory object of this project work. The interactive effects of irrigation and tillage on the maize yield and yield contributing parameters of BARI Hybrid maize-6 were observed. The determination of suitable water requirement for maize crop with effective tillage method for maize cultivation and the saving of valuable water resources were the prime concern of this project study. Significant impact of irrigation water on maize yield was observed. Under I1 irrigation treatment with zero (T1), minimum (T2) and traditional (T3) tillage practices, the seasonal water requirements were 28.30 cm, 31.30 cm and 33.00 cm respectively. In I2 irrigation treatment with zero, minimu and traditional tillage practices, the seasonal water requirements were 36.55 cm, 39.55 cm and 44.52 cm respectively and in I3 irrigation treatment with zero, minimum and traditional tillage practices, the seasonal water requirements were 48.30 cm, 53.30 cm and 62.00 cm respectively. Statistically no significant difference was found in I2 and I3 irrigation treatment for maize yield. In economical analysis, I3 irrigation treatment was not suitable because a huge amount of water was required in this treatment and net returns was low in comparison to I1 and I2 irrigation treatments. The highest benefit cost ratio (BCR), yield and net returns were found in T2I2 treatment. In three tillage treatments, the maximum yields were found in T2 (8.15 ton/ha) and T3 (8.2 ton/ha) tillage treatments and lowest was found in T1 (7.25 ton/ha) tillage treatment. The minor significant effects were found by differents tillage practices in yield and yield contributing characters of maize crop. From the economical analysis, the maximum net return was found in minimum tillage practices. Therefore, T2I2 treatment combination is preferable for maize cultivation because maximum water resources can be saved in this treatments without compromising with yield of maize in dry season (Rabi) of Bangladesh. T2I2 is the environment friendly treatment combination for maize cultivation because this treatment combination consumes minimum amount of fuel for tilling purposes and required less water resources for irrigation purposes and produces minimum amount of carbon dioxide (CO2) to the surrounding environment.
Assessment for need for additional Cyclone Shelters in some selected Coastal Zone of Bangladesh
(Department of Water Resources Engineering, 2011-09) Maruf Ahamed; Navera, Dr. Umme Kulsum
Bangladesh is one of the most cyclone affected countries. Over the last 50 years at least 30 number of cyclone hit the country. Among them 1970, 1991 and cyclone Sidr in 2007 are the severe ones. Cyclones have caused extensive damage to Bangladeshi coast line again and again. One way of saving lives during cyclones is to take refuge in safe shelters which are able to withstand the strong winds and storm surges. In Bangladesh these are called cyclone shelters. Coastal zone of Bangladesh includes 19 southern districts with 147 upazilas, covering 47,201 sq. km that comprises 32% of the total geographical area of the country. About 27% of the total population lives within this coastal zone. There are a large number of people living in the area which is cyclone and storm surge vulnerability along the western, central and south-eastern coasts of Bangladesh. However, only 10% of the actual population in the cyclone vulnerability area could be accommodated in existing safe shelters (excluding Subdistrict headquarters buildings and others public and private building). Approximately 12.5 million people will be in need of shelter places in the three cyclone-prone zones by the year 2021. Cyclone shelters are meant to provide shelter and reduce the number of casualties in the coastal area during cyclone and tsunami. After 1990 many cyclone shelters have been constructed in the coastal area by unplanned way but these are quite insufficient to accommodate all the people in the designated coastal area. In this study, the estimation of the numbers of additional cyclone shelters were calculated to accommodate the total population living in the selected study area of Kalapara and Galachipa upazila under Patuakhali district, Noakhali Sadar and Companigonj upazila under Noakhali district and Ukhiya and Teknaf upazila under Cox’s Bazar district. The proper locations of cyclone shelters would also be helpful for easy access to cyclone shelter for local people without destroying agricultural field and water bodies.
Assessment of adequacy of the water distribution network of Gazipur pourashava
(Department of Water Resources Engineering, 2002-12) Nazim Uddin, Mohammad; Bari, Dr. M Fazlul
Water distribution network of Gazipur Pourashava has been analyzed to determine the water demand and pressure at each node of the water distribution pipe network and the amount of flow in each pipe. The demand at each node was estimated using population data and per capita consumption rate. Amount of flow in pipes and pressure at various nodes were computed using EPANET2 software which is developed by US Environmental Protection Agency. In this computer programme number of pipes, number of nodes, Hazen-Williams coefficient, nodal demand, elevation of each node, node to node relations along with length, diameter, starting node number and end node number of pipes and pump capacity curve were supplied as input data. From the study the flow and pressure at each node as well as flow in each pipe were computed. Actual flow and actual pressure at each node and actual flow in each pipe was obtained by field survey. The amount of estimated water demand and actual supply and actual pressure and computed pressure in each node were compared. Similarly computed demand and actual supply in each pipe were compared. In this study it is observed that about 55% nodes have excess supply, 17% nodes meet required demand and 28% nodes experience deficient supply. Generally pressure in the distribution system under normal operating condition is very low. In this study it is also observed that about 11% nodes have sufficient pressure and the pressure of 89% nodes varies from 0.00 psi to 4.5 psi. The consumers nearer the pumping stations get more water and has tendency to waste water. Analysis of the water distribution network of Gazipur shows that the computed pressure is higher than the actual pressure measured in field. Given pumping capacity and extent of the water distribution network there is scope for improvement of supply situation. If the wasteful use of water and leakage of the supply system could be controlled, then all of the consumers could get water according to their required demand. This will require adequate management of water supply.
Assessment of crop damage due to flood using GIS technology
(Department of Water Resources Engineering, 1996-05) Mehdi Hasan; Hossain, Dr. M. Monowar
Bangladesh has a reputation for being disaster-prone. Floods, cyclones, tornadoes and droughts strike with depressing regularity and intensity. None of these hazards are new, but in recent years, there have been some significant developments. On the one hanei, the potential for loss of life, damage to property and agriculture is increasing as population pressure forces people to occupy more marginal and exposed land. On the other hand, sophisticated satellite communication systems, computer softwares now offer better warnings of impending climatic shocks and the country should generally be better prepared to cope with emergencies and to mitigate their impact. This study is set to assess crop damage due to flood using the Geographic Information System (GIS) as a tool. A part of the Compartmentalization Pilot Project (CPP) under Flood Action Plan (F AP) in Tangail has been taken as the study area. One of the main objectives of this project is to boost crop production through water management by controlled flooding. Field survey was done to obtain the existing cropping pattern. Additional data such as land contour, crop damage functions were collected from the Bangladesh Water Development Board and CPP. Flood model results for water level series were collected from Surface Water Modelling Centre (SWMC). These information were used finally in the PC ARC/INFO GIS software to assess crop damage for different years. Results obtained in the system were compared with the field situation, though a detail damage information covering a number of years on such a small area (403 hectares) as the study area, is not available. However, for the year 1995 the damage information was available. The system result for the year 1995 for with project situation shows good match with the field situation. [n this year partial water management testing was performed in the study area. For other areas, both inside and outside the project area, where the flood water of \995 flood got its way to damage crop fields, damage scenario can be compared with that of 1991. Because the years 199\ and \995 experienced almost the same kind of flood having a return period of 5 years. The sy.stem result for the y. ear 1991 also shows:; year return period damage to crops which indicates that the system that has been developed in the GIS may be considered reliable. The study showed in case of the year 1995 that no damage to crops occurred during monsoon in the study area, which complied with the field situation. In this year when nood came, water levels in the crop fields were maintained according to the farmers necessity in 80% of cropping area. Analysis was done considering the target water levels which are designed to be maintained in the crop field according to the water management plan. The result showed good match with the field situation. In the study area in 1995 no damage to crops found during field survey. Analysis with the system developed in the GIS also assessed the same result. However, sometimes it is found that the system result is over estimated. This may have occurred due to lack of information about the plantation time in the actual field condition. If in a certain area the crop fields can be identified by proper monitoring activities when the monsoon comes, the system could have been applied more efficiently in assessing crop yield or crop damage. Another expected finding is that the cropping pattern in 1995 monsoon, which has been surveyed later on, is similar to the cropping pattern that has been obtained in the present study. Actual cropping pattern in the field in 1995 monsoon, which was found out in the survey, was expected as the farmers were trained to choose and plant crops according to CPP's water management target. However GIS can be used to find out suitable cropping pattern in project planning activities especially in water management projects. Finally recommendations are put forward to apply the GIS technique for assessing nood damage to other areas of the country.
Assessment of dry season surface water availability for irrigation in polder 41/1
(Department of Water Resources Engineering, 2018-03-24) Sutradhar, Asish; Khan, Dr. Md. Sabbir Mostafa
Dry season irrigation water scarcity is a major problem in Bangladesh. During the dry period most of the land remains fallow in the coastal area due to saline water intrusion and lack of irrigation water. For the intensiﬁcation of agricultural production and protection of lives and livelihoods of the coastal communities, 139 polders were implemented in the coastal zone of Bangladesh. In the South-Eastern part of Bangladesh receives plenty of freshwater flow from the Padma and lower Meghna river through Arial Khan, Bishkhali, Buriswar and Lohalia River. As surface water irrigation is considerably less energy demanding than groundwater irrigation, Polder 41/1 has been selected as study area to assess the availability of dry season surface water for irrigation. This polder is situated in Barguna district which is in the eastern part of the southwest region of Bangladesh. Buriswar river is the main source of surface water of this polder. Salinity of this river remains below 2ds/m in all over the year. In this study, dry season irrigation assessed depending on the surface water availability in the canal system of the polder 41/1. A mathematical model is developed in this study for assessing the water availability in the canal system inside the polder. Command area of existing canal and croplands are identified from existing Digital Elevation Model (DEM) and high-resolution satellite image (Sentinel-2 and Google earth). All the existing canal and regulators are incorporate in the hydrodynamic model of polder 41/1. Irrigation water demand and water withdrawal effects are also determined for each canal. In this study, three scenarios are developed for understanding the water availability at different condition. Scenarios are developed based on the local experience which are 1) regulator control gates are always open without water withdrawal, 2) regulator control gates are always open with water withdrawal and 3) regulator control gates are used as flushing with water withdrawal. The last scenario indicates regulators gates are open when river stage is greater than canal inside the polder and it is closed when river water level is lower than the canal water level. Pumping or water withdrawal from the canals have been considered based on irrigation water requirement for each canal. In this study, daily minimum water depth for 6-hours duration is classified into three categories (water depth 0.00 to 0.50m, 0.50 to 1.0m and water depth >1.0m). It is considered that irrigation is not possible if the water depth is less than 0.50 m.
Assessment of environmental impacts of water development projects using overlay technique
(Department of Water Resources Engineering, 1998-06) Iqbal Khosru, Syed; Nishat, Dr. Ainun
Environmental Impact Assessment (EIA) has been made mandatory for all water development projects in Bangladesh, to be carried out at project planning stage. The main objective of EIA is to identify the probable effects, both beneficial and adverse, resulting from the project. Then through EIA, suggestions are given to the planners so as to minimize and mitigate the negative or adverse impacts and enhance the positive or beneficial impacts. EIA then prepares an Environmental Management Plan (EMP) for future monitoring of the project, both during and after its implementation so that sustainability is ensured. There are a number of techniques for carrying out EIA namely: Checklist, Matrices, Networks, Environmental Evaluation System, Overlay Technique, Environmental Impact Indices and Costbenefit Analysis. Besides, many institutions have developed their own guidelines for EIA. Bangladesh has adopted the Weighted Matrix method and a guidelines for carrying out EIA of water development projects has already been developed and adopted. Every method has some advantages and disadvantages in their application. As for example, Network method has been found suitable for identifying secondary and as well as tertiary impacts. Overlay technique is considered suitable for presentation of spatial variation in impacts. This study was taken up to carryout a comparative study of the various methods of EIA and evaluate whether some elements of Overlay technique can be adopted while presenting findings through Weighted Matrix method in accordance with the approved guidelines. To carry out these objectives, data available from post evaluation of the System Rehabilitation Project (SRP) were used. SRP, during 1990-95, rehabilitated 35 water development projects of the Bangladesh Water Development Board (BWDB). A multidisciplinary Evaluation Team assessed seven SRP projects, using EIA methodology. In this study, data of two projects were used. GIS based mapping technique was used to produce the Overlays. For comparison with conventional method, some important environmental components (lECs) were chosen, namely: Flood Control, Drainage, Irrigation, Crop Damage and Capture Fisheries. Other IECs, relevant to water resources development and management projects have been identified on the basis of various studies available on evaluation of completed projects. Preliminary assessment of suitability of overlay techniques and availability of data led to selection of the aforesaid five parameters. For this type of projects, modification in flooding characteristics and changes in cropping are most significant parameters. It has been found that EIA results can be better presented through Overlays for the selected IECs. Impact of probable floods, corresponding to various return periods, and matching with any river water level, on the project area, can be clearly represented by Overlay. Similarly improvement in drainage in post-monsoon condition can be better represented with spatial variations shown on the maps. Impact of the project on potentials as well as actual performance of irrigation were clearly visible in Overlay maps. Impacts on capture fisheries, studied with overlays, clearly demarked the areas of potential conflict between agriculture and fisheries. It was observed that in the projects studied, such conflict was prevalent over small areas. On the other hand flooding pattern has significantly adverse impact on agriculture. These analysis would be of great value in future water management practices. Finally it can be said that, overlay mapping can have very important role in the EIA process. The conventional method can not assess the impact and quantify the spatial variation. The method is also very flexible and the importance of the time function can be well addressed.
Assessment of environmental parameters in relation to different agro-water management practices in south-west coastal region of Bangladesh
(Departmetn of Water Resources Engineering, 2011-02) Nazia Hassan; Mondal, Dr. M. Shahjahan
Salinization of productive agricultural lands in southwestern coastal Bangladesh and their reclamation are getting distinct importance to the local people as well as policy makers. Salinization has been established as the prime cause of environmental degradation in the region and there is an urgency to find out a water management practice which is economically beneficial, socially acceptable and environmentally sustainable. Keeping these viewpoints, this study was undertaken to evaluate the present statuses of different agro-water management practices in Dumuria Upazila, to carry out laboratory analyses of selected soil and water quality parameters of agricultural fields, and to assess the environmental consequences of those farming practices. Four different types of agro-water management practices (AWMPs) with three ghers under each practice were selected for investigation. Several important soil and water quality parameters (temperature, salinity, pH, EC, TDS, DO, HCO3 -, Ca2+, Mg2+, Cl-, Na+, K+, SO4 2-, NO3 -, etc.) during the pre- and post-boro season of 2009- 10 were analyzed to calculate the mean soil and water quality change indicators (MSQI, MWQI). Besides these, management parameters, such as cropping pattern, irrigation, water exchange, use of fertilizer, use of pesticide, number of years of boro cultivation, vegetation on gher dykes, etc., and economics of production were considered for evaluation of best practices among different AWMPs using multicriteria analysis (MCA). The highest deterioration of soil quality was found in the Type-3 AWMP and the lowest in the Type-2 AWMP. In case of water quality, the order of deterioration was found to be: Type-3 AWMP > Type-4 AWMP > Type-2 AWMP > Type-1 AWMP. The degree of correlation of economic parameters with quality and management parameters was used to give weightage of parameters in MCA – a strong relation (P < 0.01) was given a high weightage and a moderate relation (0.01 < P < 0.10) was given a low weightage. Thus the Type-2 AWMP got the highest total average score and appeared to be the best AWMP. This was due to the community management approach for controlling saline water into the ghers, use of more organic fertilizer, use of IPM techniques, less cropping intensity, less deterioration of soil and water quality, higher economic return, etc. So, from this study it can be said that the communal approach in water management for HYV boro rice cultivation with a crop rotation of golda-bagda-white fish is the best AWMP among the current practices in the study area
Assessment of ground water vulnerability in selected districts of Bangladesh using drastic index
(Department of Water Resources Engineering (WRE), 2023-08-02) Zannatul, Ferdausi Sumi; Yunus, Dr. Anika
Around 75% of population of Bangladesh relies on groundwater for potable supplies and it is also extensively usedfor irrigation purpose during the dry season.Therefore, pollution of groundwater is a crucial issue. In this study, the pollution potential of three districtsof Bangladesh in Pabna, Sirajganj and Natore has been determined using DRASTIC indices.DRASTIC is a methodology that systematically evaluates the pollution potential of groundwater of an area. DRASTIC is acronym of depth to ground water, net recharge, aquifer media, soil media, topography, impact of vadose zone and hydraulic conductivity. It is then combined with weights and ratings to produce drastic index value. As the objective of the study was to determine the temporal variation of vulnerability of groundwater pollution ofPabna, Sirajganj and Natore district by DRASTIC index. Vulnerability of groundwater was determined for three seasons that is pre-monsoon, monsoon and post-monsoon periodsconsist of March to May, June to October, November to February respectively. For pre-monsoon period The DRASTIC index value range for Pabna, Sirajganjand Natore districts are83-109, 83-105 and 105-141respectively which indicates that Pabna has very low to low vulnerability,Sirajganjfalls under the same categoryand Natore district shows low to moderate vulnerability. For monsoon period The DRASTIC index value range for Pabna, Sirajganj and Natore districts are113-147, 121-146 and 123-141 respectively which indicates that Pabnaand Sirajganjfalls under the same categorylow to moderate vulnerabilityand Natore district also shows the same results. For post-monsoon period The DRASTIC index value range for Pabna, Sirajganj and Natore districts are113-135, 113-135 and 93-113 respectively which indicates that Pabnaand Sirajganjfalls under low to moderate vulnerability and Natore district falls under very low to low vulnerable areas. The objectivewas also to determine which parts of the areasare more vulnerable than other. From the study it is also found that in these three districts there is urban area where pollution potential is very low due to covered soil surface as waste materials cannot seep through it. It is hoped that this study will be helpful in future development and land use planning of this area and also assist in prioritizing protection, monitoring and cleanup efforts.