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সর্ব-শেষ হাল-নাগাদ: ২৭ মার্চ ২০১৯

টেকনিক্যাল জার্নাল; ভলিউম-১৪, নাম্বার-১, ডিসেম্বর ২০১৮

 

USABLE WATER ASSESSMENT FOR NORTH-EASTERN PART OF BANGLADESH: A CASE STUDY

 

E. Shaik1* and M. T. Islam1

 

1Water Resources Planning Organization, WARPO Bhaban, 72 Green Road, Dhaka-1215.

*Corresponding Author (E-mail:ershad.ju@gmail.com)

 

Abstract

The agro-based north-eastern haor region of Bangladesh is very important for crop production and food security of the country. The irrigated crop of dry season faces useable water scarcity. So usable water assessment during the dry season is very important for agro-based Haor area to know the extent of necessary surface water development measures for the study area. At the same time, Haor area is engulfed with various water-related problems and constraints viz. pre-monsoon flash flood and seasonal flood due to excess rainfall, climatic var iability, river capacity reduction; water logging due to unplanned road construction and canal or creek filled up, disruption of hydraulic connectivity between Haor and river and dry seasonal water scarcity. The study intends to explore the dry season water security which one of the major concerns for the development of agro-based north-eastern Haor region of Bangladesh. The distinct water scenarios like status of usable water in terms of stream flow, static flow, dependable rainfall, and usable groundwater during dry season is estimated which necessitate assessment of crop water demand and supply requirement to know the spatio-temporal scenario of water whether surplus or deficit is important for regional policy planning and water management of the study area.

 

Keywords: rainfall, evapotranspiration, crop production, crop water demand, usable water.

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SHIFTING OF ENERGY SOURCE FOR SHALLOW TUBEWELL IRRIGATION SYSTEM: A FIELD STUDY

 

M. A. Hossain1* and M. T. Iqbal2

 

1Geotechnical Research Directorate, River Research Institute, Faridpur-7800.

2Dept. of Agronomy and Agricultural Extension, Rajshahi University, Rajshahi.

*Corresponding Author (Email: alauddin_1968@yahoo.co.uk).

 

Abstract

Shallow tube well (STW) is the main device for groundwater abstraction for irrigation purpose in Bangladesh. This paper focuses shifting of STW energy source used in the study area. Field survey was carried out in Digholkandi Union comprises five mauzas under Ghatail Thana of Tangail district in 2017 with a view to examine the quantity and type of energy used of STW, to identify the trends line of energy type from a base line and to address the causes of shifting from one to another. Primary and secondary data were used in this study. Primary data were collected through questionnaire survey and financial as well as sensitivity analysis were done to predict the profitability of STW irrigation business. The study revealed that two types of irrigation equipment were mainly used in the study area for groundwater abstraction. In 2007, diesel operated STW (DOS) was 44% and electricity operated STW (EOS) was 56% in the study area. In 2017, field survey data showed that DOS was only 4% and EOS was 96% in the study area. Last ten years using of DOS and EOS has been decreased and increased 40% respectively. DOS is in abolition stage and EOS has been reached tends to 100%. Study findings showed that EOS was highly profitable than DOS due to lower electric charges compared to fuel and lubricant cost and coverage of higher command area by EOS promoted the irrigation business. Some recommendations have been included in this paper for the sustainability of STW irrigation business.

 

Keywords: GIS application, location and mapping of STW, cropping pattern, command area.

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FLOOD HAZARD MAPPING OF SURMA RIVER BASIN IN SYLHET CITY

 

G. M. Munna1*, M. J. B. Alam1, M. M. Uddin1, and M. T. Rahman1

 

 1Dept. of Civil and Environmental Engg., Shahjalal University of Science and Technology, Sylhet.

*Corresponding Author (E-mail: gmunna192-cee@sust.edu)

 

Abstract

 

As flood is one of the major disasters of Bangladesh and does immense damage to the lives and livelihood of locals living near or in the flood prone zones, it is necessary to study all possible water bodies and their nearby areas. The popularity of using software based data management tools to justify existing vulnerabilities and the overall status of flood and flood hazard in Bangladesh has been observed in recent years while many studies of flood hazard have been found in the literature. It was therefore aimed in this current study to determine the status of flood throughout the years 2006 to 2015 in the district of Sylhet. The discharge capacity of Surma River has been calculated for 25 year return period and a flood hazard map has been generated using GIS which shows the river has not sufficient capacity to carry all the water during peak flow which results in water logging in Sylhet city. Although the overall capacity of the Surma River is much larger than the total yearly discharge and runoff, caution is necessary for a flash flood. At the end, the digital elevation model has been used to understand the elevation of the study area.

 

Keywords: flood, geo-statistics, GIS map, hazard, ordinary kriging, Surma River

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FEASIBILITY OF PREPAID IRRIGATION AT RAJSHAHI REGION IN BANGLADESH

 

M.A. Kashem1and M. Sq. Rahman2*

 

1Barind Multipurpose Development Authority, Rajshahi.

2Dept. of Agril. and Industrial Engg., Hajee Mohammad Danesh Science and Technology University, Dinajpur.

*Corresponding Author (Email: m_sq_rahman@yahoo.com)

 

Abstract

 

Since water is scarce and essential resource for crop production, Barind Multipurpose Development Authority (BMDA) in Bangladesh has invented and has implemented prepaid irrigation program -a new an efficient irrigation program. This study was conducted to identify the better irrigation program for crop production. BRRI-Dhan-28 was selected and cultivated using equal quantity and ratio of similar fertilizers for all the sample plots. The results showed that per Bigha (1350 m2) average irrigation charge for prepaid irrigation program was Tk. 699 and for private irrigation program was Tk.1480 which was about 112% higher than the prepaid irrigation program. The amount of water per Bigha for Boro rice cultivation were 59 and 82 bigha-inches for prepaid and private irrigation programs, respectively. It showed that about 39% excess water was used by the private irrigation program. Volumetrically the loss of water for using the private irrigation was about 780 m3per bigha. Average yield per bigha was increased about 9% in the prepaid over private irrigation. Net income per bigha in the prepaid and private irrigation programs were Tk.5700 and Tk.4000, respectively. Benefit–cost ratios of prepaid and private irrigation programs were 2.36 and 1.79, respectively. Total loss of irrigation water due to private irrigation program was found about 19830 million cubic meters per year which could produce about 9.46Million Metric Ton rice. This study confirms that prepaid irrigation program is an economic and environment friendly program to grow more rice in the study area.

 

Keywords: feasibility, prepaid irrigation, economic.

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HYDRODYNAMIC SCENARIO’S TO REDUCE THE SALINE WATER INTRUSION IN THE SOUTHWEST REGION OF BANGLADESH

 

M. Z. Rahman1* and U. K. Navera2

 

 1Coast Port and Estuary Management Division, Institute of Water Modelling, Dhaka-1206.

2Department of Water Resource Engineering, Bangladesh University of Engineering & Technology, Dhaka.

*Corresponding Author (Email: zia@iwmbd.org).

 

Abstract

 

Salinity in Bangladesh coastal area is dependent on tidal flow, rainfall intensity, evaporation, freshwater flows from upstream and the impact of climate change like sea level rise (SLR). Due to the reduction in freshwater flow from the upstream rivers in the dry season, the average salinity concentrations in the coastal part are higher in dry season than in the monsoon. The flow of Ganges River within Bangladesh reduced significantly due to the withdrawal of water in the upstream boundary. The simulation of the calibrated salinity model for the Southwest region in Bangladesh has been carried out in this study to explore the hydrodynamic scenarios which may reduce the salinity level at the above mentioned area. The scenarios are based on different flow conditions and have been simulated with the calibrated and validated hydrodynamic and salinity model. The scenario considering the increase in upstream flow through Ganges and its connected rivers has been simulated to identify the saline free zone at the most southern end zone. Salinity level remains higher in the western part of the Southwestern region than that of the eastern part. The eastern part remains less saline since it receives freshwater flow through Arial Khan, Bishkhali and Buriswar Rivers. As a result, salinity levels in the region decreases from west to east. It was observed that the some of the major rivers of Southwest would be saline free and all other rivers will have significant reduction of salinity due to increase in flow of fresh water through the Ganges and its distributaries.

 

Keywords: augmentation, Bay of Bengal, freshwater, hydrodynamic, MIKE 11, MIKE 21 FM, salinity, southwest.

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SELECTION OF A BRIDGE LOCATION OVER THE RIVER LOHALIA: AN ASSESSMENT USING MIKE 21C MODEL

 

A. K. M. Ashrafuzzaman1*, M. A. A. Moududi1, M.M. Hasan1, S. K. Das1, M. A. Hossain1and P. Kanungoe1

 

 1Hydraulic Research Directorate, River Research Institute (RRI), Faridpur-7800.

*Corresponding Author (Email: akmashrafuzzaman@rri.gov.bd)

 

Abstract

 

Choosing the ideal site for a bridge is as important as constructing the bridge itself appropriately. There is a range of location suitability criteria and models that assist in analyzing site suitability. This study is an attempt to determine the suitable location of a proposed bridge along with its alignment as well as approach road using MIKE 21C model over the Lohalia river in Patuakhali district. This study also provides hydraulic design parameters of the bridge as well as its approach roads. A field survey campaign has been conducted to collect field data necessary for model development and hydro-morphological study. The model was calibrated using field data and then applied for different scenario simulations in the base and with bridge conditions. It is revealed from the study that the bridge should be located at the inflection point between two consecutive meander bends near the Boga ferry terminal from hydro-morphological considerations. The suggested bridge length of 980m is much larger than that obtained from regime equation in order to fulfil specified navigational requirements. For the bridge pier and abutment, the design scour level is found as -16.46mPWD and -6.9 mPWD respectively. The study also comes up with design discharge, water level, girder bottom level and deck level of the bridge. Moreover, location and dimension of the approach road, slope protection works, river training works and design variables of the same have also been suggested from the study.

 

Keywords: approach road, BIWTA, bridge, hydraulic design, MIKE 21C, thalweg.

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COMPARISON OF POLLUTANT REMOVAL EFFICIENCY BETWEEN SUB-SURFACE FLOW WETLANDS FOR MUNICIPAL WASTEWATER

 

U. Habiba1, P. Sarker1* and F. R. Rubaba1

 

 1Dept. of Civil Engineering, Ahsanullah University of Science & Technology, Dhaka-1208.

*Corresponding Author (Email: pubali777@gmail.com)

 

Abstract

 

Constructed wetlands have been used for decades mostly for the treatment of domestic or municipal wastewater. It is a treatment system that uses natural processes involving wetland vegetation, soils, and their associated microbial assemblages to improve water quality, which is low in energy consumption, requiring minimal maintenance. The overall objective of this study was to assess the performance of two subsurface flow constructed wetland to treat municipal wastewater. The specific objectives were a comparative study of pollutant removal efficiency between horizontal and vertical flow wetland system using stone chips, coal and sawdust as media evaluate the removal performance of pollutants from municipal wastes such as pH, alkalinity, turbidity, TSS, TDS, BOD5, fecal coliform, NO− 2and NO−3. The two systems had an identical configuration; each consisted of a subsurface vertical flow (VF) wetland and a horizontal flow (HF) wetland. The wetlands were planted with Canna indicia and employed with stone chips, coal and sawdust media. The results were impressive. Vertical flow constructed wetlands are more efficient in reducing pH, turbidity, and E.coli from water than horizontal flow systems. The removal efficiency of total suspended solid varies in the range from 30-40%, BOD5 ranges from 75-90%. Horizontal flow constructed wetlands are more efficient in removing dissolved solids from water and provide efficient color removal under predominantly anaerobic condition. The results provided a strong evidence to support widespread research and application of the constructed wetland as a low-cost, energy-efficient, wastewater treatment technology in Bangladesh.

 

Keywords: coal, constructed wetland, horizontal flow, removal efficiency, sawdust, stone chips, vertical flow

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EFFICACY OF DIFFERENT LAUNCHING MATERIALS IN RIVERBANK PROTECTION: A LABORATORY-SCALE MODEL STUDY

 

A. K. M. Ashrafuzzaman1*, M. A. A. Moududi1, M. L. Rahman1, S. K. Das1, M. M. Hasan1, M. Tofiquzzaman1, S. K. Ghosh1, A. A. Imranand S. Afrin1

 

 1Hydraulic Research Directorate, River Research Institute (RRI), Faridpur-7800.

*Corresponding Author (Email: akmashrafuzzaman@rri.gov.bd)

 

Abstract

 

There are many different types of materials that are utilized for slope protection nowadays to save the riverbank against the wave action, current of the river or surface run-off. In general, cement concrete (CC) blocks, stone chips, geo-textile bags (geo-bags) filled with sand are widely used in revetment works in Bangladesh. A study was undertaken to determine the launching behaviour of these bank protection materials to find out the cost-effective and sustainable solution for riverbank protection using scale model. In order to fulfil the objectives, an undistorted model having a scale of 1:30 was designed using Froude’s model law. The model consists of two channels namely, the main channel and oblique or shoot channel. Discharges had been fed in the model with the discharge ratio of Qshoot/Qmain= 0.8 and 1. The study showed that the scour decreases once the discharge ratio changes from 0.8 to 1.0. However, scour was augmented, under full oblique flow condition (i.e. only shoot channel was opened while the main channel remain closed) than that of under oblique flow condition (when both channels were opened). Moreover, it was observed that the combined apron (geo-bags and CC blocks) works better as compared to single geo-bags or even only CC blocks as launching materials. Finally, the study showed that the cost involved in case of launching apron of composite materials was around 34-35% less than that of the single composition of CC blocks provided.

 

Keywords: CC blocks, geo-bags, launching apron, launching material, oblique flow, spur, stone chips

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QUALITY ASSESSMENT OF IRRIGATION WATER OF BIRGANJ UPAZILLA UNDER DINAJPUR DISTRICT

 

M. A. Hossain1*, R. K. Barma2, M. A. Kashem3, Milufarzana2, M. M. Hasan2, M. Sq. Rahman2

 

 1Geotechnical Research Directorate, River Research Institute, Faridpur-7800.

2Dept. of Agril. and Industrial Engg., Hajee Mohammad Danesh Science and Technology University, Dinajpur.

3Barind Multipurpose Development Authority, Rajshahi.

*Corresponding Author (Email: alauddin_1968@yahoo.co.uk)

 

Abstract

 

Water with adequate quality and quantity is very important for irrigation to ensure the crop yields and quality. Keeping in mind it, an investigation was carried out in Birgonj Upazilla under Dinajpur district of Bangladesh in 2017 to assess the extent of groundwater quality and suitability for irrigation purpose. In this connection 50 groundwater samples were collected during irrigation period from eleven unions at different locations and analyzed the samples in the laboratory with respect to international irrigation water quality standards and Bangladesh standards. Analyses were included the determination of pH, EC, TDS, cations (Ca2+, Mg2+, Na+, K+, Cu2+, Mn2+, Fe3+) and anions concentration (HCO3-, SO42-, PO43- and Cl-). In addition, some water quality determining parameters such as sodium adsorption ratio (SAR), soluble sodium percentage (SSP), hardness (HT), permeability index (PI), potential salinity and Kelly’s ratio were computed to assess the suitability of groundwater for irrigation. Results showed that almost all the water samples were within the recommended value for irrigation as GoB and WHO standards. Based on results from the laboratory analyses it was observed that the groundwaters of the study area were suitable for irrigation and safely be used for irrigation and would not affect the soils, crop yield and quality. The results also provided base line data for water quality of groundwater resources of the study region to match national and international standards for irrigated agricultural requirements.

 

Keywords: quality assessment, irrigation water, suitability, analysis, cations, anions.

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EXPLORING ORGANIC MATTER PRESENCE IN SOILS AND ITS EFFECT ON ENGINEERING PROPERTIES OF GOPALGANJ DISTRICT

 

U. Saha1*, M. Moniruzzaman1, F. Rukshana1, S. R. Chowdhary1 and S. Ferdhous1

 

1Geotechnical Research Directorate, River Research Institute (RRI), Faridpur-7800, Bangladesh

*Corresponding Author (Email: umasaha_65@yahoo.com)

 

Abstract

 

The presence of organic matter (OM) in soils changes its behavior in engineering practice. The design engineer should take concern for this and that’s why it is important to ensure the presence of either OM is in soil or not. So, laboratory investigation of presence of OM in soils is of great importance for designing structures. In Bangladesh, Gopalganj district is one of the low lying depression areas where OM presents in the sub-surface soil. Under these circumstances this paper has been attempted to explore the presence of OM in soil in Tungipara, Gopalganj sadar and Kotalipara upazila of Gopalganj district. Soil samples have been collected from Bangladesh Water Development Board (BWDB) and the engineering properties of soils have been determined at the Geotechnical Research Directorate of River Research Institute (RRI). After the analysis of data, organic matter has been found up to 32´ at Tungipara, up to 17´ at Gopalganj sadar and up to 22´at Kotalipara upazilla. It has also been observed that the natural moisture content, liquid limit and plasticity have been increased with the increases of organic matter content. Here it is remarkable that organic matter contents in Tungipara are 5% to 32% and their corresponding SPT values are 1 to 6, organic matter contents in Gopalganj sadar are 5% to 20% and their corresponding SPT values are 2 to 4 and Kotalipara 5% to 16% and their corresponding SPT values are 2 to 4. Though effect of organic matter presence in soils on SPT has been demonstrated here but not remarkable effect has been observed.

 

Keywords: liquid limit, natural moisture content, organic matter content, plasticity index, standard penetration test.

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