Abstracts of M.Sc. (WRD) Theses

 

 

 

Thesis title:

CHANGES OF ENVIRONMENTAL PARAMETERS DUE TO SALINITY INTRUSION IN THE SOUTHWEST REGION OF BANGLADESH           

 

Name of the student:

            MD. NAZIM UDDIN 

 

Name of the Supervisor:

            Dr. Anisul Haque

 

Date of award of M.Sc.:

            October, 2005.

 

Abstract:

            The study was undertaken to assess and identify the spatial and temporal changes of salinity with upstream river discharge, mean tide level and local rainfall. The main focus was to identify the environmental changes with salinity regarding fisheries and agriculture as well as development of an empirical relationship between salinity and environmental parameters. Two different zones such as High saline Zone and Moderate saline Zone, namely Paikgacha and Rampal, respectively, were included in the study. Information was collected from two categories viz. fisheries and agriculture farmers through semi-structured questionnaire regarding the changes of environmental parameters due to salinity over the 30 years period from 1975-2005. Some useful indices of species structure in communities and conventional statistical techniques were used.

 

The study has revealed that in Paikgacha, the salinity varies within the range from 20,000 to 45,000 micro-mhos and in Rampal it is from 10,000 to 30,000 micro-mhos. It has shown that a limited degree positive and negative relationship exists between salinity and river discharge, and mean tidal water level and local rainfall but those relationships are significant statistically. It has been found that rainfall and river discharge are the key factors to control salinity for Paikgacha and Rampal respectively.

 

Salinity intrusion has caused severe threat to the fresh water fish diversity. The species in Paikgacha and Rampal have been reduced from 29 to 12 and 24 to 18 respectively during the period 1975-2005. Species diversity, richness and evenness have been decreasing in both areas but it is more visible in Paikgacha. Fish diversity (H-), richness (d) and evenness (e) have been reduced in Paikgacha from 3.272 to 2.409, 6.956 to 3.376 and 0.972 to 0.969 respectively during the study period. Whereas, in Rampal, H-, d, and e have been reduced from 3.148 to 2.844, 5.51 to 4.82 and 0.991 to 0.984 respectively. Dominancy of saline tolerant species has also increased in both regions but severe in Paikgacha. Presently the farmers of these areas are more interested in shrimp and carps. Habitat loss is also the cause of diversity loss. Small land holders are selling/leasing their lands to shrimp cultivators that results in the change of ownership pattern in both areas.

 

Due to salinity intrusion, indigenous rice varieties have been reduced by 75% in Paikgacha and 33.33% in Rampal during the period 1975-2005. Rice yield has been decreased by 67.30% and 69.70% in Rampal and Paikgacha respectively during the study period. Rabi vegetable has been affected more than kharif vegetable. It results in lowering the diversity index value of Paikgacha and Rampal from 2.766 to 0.694 and 2.685 to 2.349 respectively during the study period. Saline intolerant species have been departing and saline tolerant species like babla, khejur, etc are dominating in both regions due to salinity. It has reduced plant diversity index value from 3.397 to 2.530 in Paikgacha and 3.537 to 2.931 in Rampal during the period 1975-2005. There is no remarkable change in cropping pattern and intensity in both regions. Most of the people of these two areas are more interested in rice cum fish farming but in Rampal, people are also interested in rice cum fish and freshwater fish culture.

 

No empirical, semi-empirical or analytical equation exists to compute the change of environmental parameters as a result of change of physical parameters like salinity. In this regard, an attempt was made to develop an empirical equation. The equation was developed for Paikgacha but is not generally applicable to other areas.

 

 

 

 

 

 

Thesis title:

PLANNING FOR INTEGRATED STORM WATER DRAINAGE MANAGEMENT OF THE LOWER PART OF MALNICHARA IN SYLHET CITY

 

Name of the student:

            REZAUL KABIR CHOWDHURY

 

Name of the Supervisor:

            Dr. Rezaur Rahman

 

Date of award of  M.Sc.:

            December 12, 2005.

 

Abstract:

            Malnichara is one of the nine natural drainage channels of Sylhet City responsible for storm runoff conveyance to the Surma River. Two other channels, Kalibari chara and Gaviar chara meet with the Malnichara prior to discharge in Surma River. In the city, Malnichara has a total length of 9.5 km. The channel has been found to be encroached by temporary and permanent structures at many points of the city and subsequently increase the vulnerability to inundation after heavy rainfall. Traditionally storm drainage facilities in Bangladesh are designed with a view to conveyance of storm water as early as possible to the receiving water bodies. Environmental and social considerations are not taken into account. In this study, integrated storm water drainage management plan for the Malnichara lower part in Sylhet city has been carried out. Three options (natural channel, lined natural channel and box culvert) improvement have been evaluated with respect to technical, economic, environmental and social criteria.

 

Catchment area of Malnichara in Sylhet city has been identified from field survey and contour map. It has been divided into three sub area namely Kalibari Chara Sub Area I, Gaviar Khal Sub Area II and Malnichara Sub Area III. Corresponding areas were found to be 1.47 sq.km, 0.8 sq.km and 8.0 sq.km respectively. 1-hour maximum rainfall data have been generated from 24-hour maximum rainfall data of Sylhet for the period of 1970-2002 using Indian Meteorological Department (IMD) reduction formula. Extreme Value Type I probability distribution has been used for frequency analysis of 1-hour maximum rainfall. Short duration rainfall IDF curve has been developed for the study area. Based on rational formula, peak discharges at the outfall of Kalibari Chara, Gaviar Khal and Malnichara have been calculated to be 25.83 m3/s, 17.22 m3/s and 76.33 m3/s respectively. Existing cross sectional area of Malnichara have been measured by staff gauge and measuring tape at different locations: Choukidekhi, Badambagicha, Housing Estate, Jalalabad R/A, Sagor Dighir Par and Kanishail. Corresponding area were found to 7.43, 15.71, 14.13, 29.74, 40.62 and 47.73 sq.m respectively. Design of pipe sewer was found technically infeasible due to the requirement of large diameter. For the Choukidekhi to Kanishail portion of Malnichara, designed sections were found as trapezoidal natural channel (bot.width 10 m., depth 7 m and side slope 1:2), rectangular lined natural channel (10 m by 5 m) and concrete box culvert (width 8.5 m by depth 5 m). And for the Kanishail to Topoban portion, natural channel (bot. width 13.5 m and depth 7.5 m with side slope 1:2), lined natural channel (width 13 m and depth 5 m) and box culvert (width 11 m and depth 5 m). Water quality analysis reveals that the concentrations of phosphate, ammonia-nitogen and faecal coliform have been increased in Malnichara from Choukidekhi to Topoban, and in the Surma River concentrations increased from upstream to downstream of Malnichara offtake point. Total solid concentration in Malnichara was found to decrease from Choukidekhi to Topoban.

 

Multi Criteria Analysis (MCA) has been performed to evaluate three options of Malnichara improvement with respect to nine criteria of risk of design failure, construction cost, maintenance cost, water quality deterioration, sediment deposition problem, land acquisition problem, necessity for legal action, opportunity for vehicle movement and infrastructural development, and opportunity to improve aesthetic. All criteria have been assigned equal weights.  It has been found from MCA that natural channel is the best option of Malnichara improvement. It is found from sensitivity analysis that selection of alternative is sensitive to social criteria. 

 

 

 

 

 

 

 

Thesis title:

An Optimization Model for a Selected Region of Dhaka WASA Water Supply System

 

Name of the student:

            Mohammad Aminur Rahman Shah

 

Name of the Supervisor:

            Dr. M. Shah Alam Khan

 

Date of award of  M.Sc.:

            April, 2003

 

Abstract:

            With the rapidly growing urbanization, Dhaka city is facing shortage of water supply for many years. In Dhaka city, Dhaka Water Supply and Sewerage Authority (DWASA) is responsible for municipal water supply through a piped network. DWASA can meet up to about 95% of the total demand. DWASA is facing difficulties in managing the water production system due various reasons. So, optimum utilization of existing resources is essential to run the water supply system effectively. Understanding the situation, this study was intended to develop a linear optimization model for a piped ground water supply system. The objective of the study was to optimize cost of water production from different production wells in a selected service area of DWASA at different levels of demand. Uttara thana of Dhaka city is selected as study area where water supply comes from 15 Deep Tube Wells (DTWs).

 

A linear optimization model has been developed for Uttara water supply system. The objective function is to minimize water production cost. The decision variable is amount of water to be produced from each DTW. The constraints are the water production capacity of each DTW, total water demand, minimum limit of water production from each DTW. It is assumed that the head loss of water in the distribution pipe and deviation of production due to varying static water level in housing pipe of DTW has no effect. Also considering the practical situation, it is assumed that each DTW must operate for minimum water production to continue supply to its local coverage. The optimization model was run using LINDO software.

 

The optimization model has been applied for water production records of two financial year: July 2001-June 2002 and July 2002-June 2003. It is observed that maximum 57 % of actual cost can be reduced by using DTW scheduling through the optimization model. Always low-cost DTWs were selected first to meet the demand and high-cost DTWs remain for minimum water production. One of the important outputs of the model is the scheduling of DTW operation, which gives combination of DTWs to be operated to minimize cost. In addition, two scenarios – increasing and decreasing number of DTW has been analyzed with the model and found that the model will give effective solution in critical situation.

 

Although several assumptions were made during model development due to unavailability of records, this optimization model for Dhaka WASA water supply system will open the future path in effective decision-making and good management of DWASA. Further study on head loss in water distribution network and groundwater level is required to improve the model closer to the real condition. However, this optimization model will be an effective tool for decision-making on water supply in a central water supply system, like Dhaka WASA.

 

 

 

 

 

 

 

Thesis title:

Solar Dimming in Bangladesh and Its Potential Impacts on Rice Evapotranspiration and Production

 

Name of the student:

            Sinora Zaman

 

Name of the Supervisor:

            Dr. M. Shahjahan Mondal

 

 

Date of award of  M.Sc.:

            09 February, 2009.

 

Abstract:

            Solar radiation is the dominant, direct energy input into the terrestrial ecosystem and it affects all physical, chemical and biological processes. The sun exerts a natural influence on the earth's atmosphere and climate. In order to understand mankind's roles in climate change, the sun's impact must first be understood. For its importance in the climate system, many countries in the world conducted studies regarding solar radiation. Such an attempt has been made in this study.

 

Sunshine duration data at nine meteorological stations (Dhaka, Rangpur, Rajshahi, Sylhet, Barisal, Comilla, Khulna, Chittagong and Cox’s Bazar) are analyzed to see the long-term changes and trends. The stations are selected such that they represent all hydrological regions of Bangladesh and spread more or less uniformly all over the country. The data used are the Bangladesh Meteorological Department data spanning from 1961 to 2006. The analysis is based on 36 ten-day periods in a year. A decreasing trend in sunshine duration is found at all selected stations and in almost all 10-day periods. The overall annual decrease for the entire Bangladesh is found to be about 0.3 hours a day in every 10 years. The decrease is the highest in the winter season (November-February), then in the summer (March-May) and lowest in the monsoon (June-October). The highest annual and seasonal decreases are found at the Dhaka station. The maximum decreasing rate (0.63 hours a day in every 10 years) is found in the last 10-day period of January, the coldest month in the winter season. Annual sunshine hour has decreased by almost 20% from 1961 to 2006. Statistical significance of the decreasing trends was also tested at a 10% level of significance. It was found that the trends are statistically significant at 29, 19, 17, 15, 8, 5, 5, 5 and 3 ten-day periods, out of 36, for Dhaka, Barisal, Sylhet, Chittagong, Cox’s Bazar, Rajshahi, Rangpur, Khulna and Comilla stations, respectively.

 

To assess the impact of decreased sunshine hour on rice evapotranspiration, FAO recommended CROPWAT software was used to calculate reference crop evapotranspiration (ET0). Sunshine duration for the years 1961 and 2006 was estimated by fitting 36 regression equations to 36 ten-day average sunshine duration time series. For the years 1961 and 2006, ET0 was calculated with their respective sunshine duration keeping other climatic parameters (temperature, humidity and wind speed) unchanged. It was found that the annual ET0 has declined by 6.1% from 1961 to 2006 due to the decline in sunshine duration. The ET0 values were multiplied by crop factor (Kc) for Boro rice to obtain rice evapotranspiration (ETc). As the crop factor is a fixed factor, similar decreases in ETc were found.

 

To assess the impact of decreased sunshine hour on Boro rice yield, a widely used rice growth model called ORYZA 2000 was used. The model was run with the average climatic data on temperature, humidity and vapor pressure but with changing sunshine duration data for 1961 and 2006. It was assumed that there are no water and nitrogen deficits during the growing period of rice (January-May). The results revealed that the Boro yield may have decreased by 4.3% due to the decrease in sunshine duration from 1961 to 2006. As this study was based on secondary data and information and as many input parameters needed in the model were not available for the rice varieties commonly grown in Bangladesh, the actual impact of solar dimming may be more than that found from the model results. Further research is needed in this aspect.

 

 

 

 

 

 

 

Thesis title:

MANAGEMENT OF STORM WATER FOR DRAINAGE OF AZIMPUR, BUET, AND LALBAG AREA OF DHAKA CITY

 

Name of the student:

            NOOR AHMED

 

Name of the Supervisor:

Dr. A.K.M. Saiful Islam

 

Date of award of  M.Sc.:

            September, 2008

 

Abstract:

            In the recent years, it has become a common picture in Azimpur, BUET and Lalbag that if there is a rainfall of moderate to severe intensity, major portion of the area goes under water. This study focuses on the flooding caused by high intensity storm runoff that inundates these areas for several days mainly due to lack of proper drainage system and inefficient management.

 

Selection of study area is guided by the availability of surface runoff and short duration rainfall data of the urban catchments. Delineation of the catchment was based on storm sewers of DWASA, street map of DCC, Google Earth Image, previous study and field observation. Since the land is very flat, the catchment boundary depends very little on the topography.

 

Mike SWMM rainfall runoff Model is a popular, effective and useful tool, which can support planning and management for making effective decision. In this study Mike SWMM runoff module is used for runoff generation and Extran module is used for simulation of the surface flow.

 

In this study two catchments are delineated for simulation of old and new storm sewers by Mike SWMM model. One catchment is the old storm sewer of BUET and the other is the newly constructed storm sewer which goes through BUET, Dakeshwari Mondir and part of Azimpur and Lalbag areas. BUET catchemnt is divided into 17 subcatchments to simulate the old storm sewer network. Calibration and verification is possible for sub-catchment no-6 of old storm sewer network for the year 1996. Measured runoff and rainfall data is found only for this subcathcment for the year 1996. SWMM Extran block run was not possible for lack of data on the old storm sewer. New storm sewer goes through the part of the BUET catchment. So, catchemnt boundary for new storm sewer is different from old storm sewer catchment. This catchment is divided into 63 sub-catchments.

 

I-D-F curve is used to generate 5 minutes interval rainfall data with a statistical return period of 2, 3, 5 and 10 years. Cumulative rainfall of 2, 3, 5 and 10 years return period is accordingly 81.57 mm, 91.90 mm, 105.94 mm and 123.58 mm.

Rainfall and storm sewer discharge data for the 1996 monsoon at BUET catchment was collected from a provious study (chowdhury et al., 1998). The information on the drainage network (secondary and primary/trunk drain) of the model area were collected from DWASA. Old network data is not available and recently installed sewer system drawing is available for the BUET catchment. It includes detailed information about the dimension and bottom elevation of the pipes, location and size of the manholes and catchpits.

 

A set of small, medium and large storms were selected from monsoon 1996 and divided into two sub-sets of equal size, one for calibration and the other for verification. Root mean square errors for calibrated storms are according 3.5%, 12.07% and 16.10% and correlation coefficients (R2) are 0.917, 0.951 and 0.913.

 

Old storm sewer network surface flow simulation is not possible because of lack of sewer data. Subcatchment parameters of the old storm sewer of BUET catchment is used in the new storm sewer catchment. SWMM Extran Block is used to test the capacity of newly constructed storm sewer. Although in the Master Plan (JICA, 1992) the rainfall intensity with a 5-year frequency was recommended to design the storm sewer, it is inadequate to handle the 2 year frequency rainfall.

 

Planning, design, operation and maintenance of urban drainage systems are a great challenge to urban authorities in developing countries because of unplanned development activities. Short design return periods are sometimes necessary because of the prohibitive cost of building a drainage system to cope with all monsoon storms. Integrated approach is needed among the government agencies to stormwater management, and public participation based on awareness of the purpose and function of the drainage infrastructure.

 

 

 

 

 

 

 

Thesis title:

Trends in Climatic Variables and Their Combined Effects on Irrigation Water Demand in the Dry Season

 

Name of the student:

            Farzana Nasrin

 

Name of the Supervisor:

            Dr. M. Shahjahan Mondal

 

Date of award of  M.Sc.:

            13 January, 2009.

 

Abstract:

            Agriculture is a key economic sector in Bangladesh and one of the main users of fresh water resources. At present, climate change is thought to be putting extra stress on agricultural productivity and hence food security because climate change may lead to changes in irrigation water requirement. Most of the studies related to the effects of climate change on irrigation water requirement have been done based only on changes of temperature and/or rainfall. Other climatic variables, such as solar radiation, humidity and wind speed, which may also affect the irrigation water requirement, were not taken into consideration in those studies. To find out the impact of climate change on agricultural water requirement, the combined effects of all the variables need to be considered.

 

This study is based on secondary data and information. Data of four meteorological stations, namely Dhaka, Jessore, Bogra and Chandpur, on daily observations of air temperature, air humidity, wind speed, solar radiation and rainfall are used. The stations are selected such that one station is selected from each of the North-Central, South-West, North-West and South-East hydrological planning regions of Bangladesh. 10-day time scale for data analysis has been used as it closely resembles agricultural and water resources planning activities in Bangladesh. The Penman-Monteith method is used for reference crop evapotranspiration (ET0) computation and both parametric and non-parametric methods are used for testing the statistical significance of trends in different hydro-climatic variables.

 

The results of the analysis reveal that maximum temperature has increasing trends of 0.20C, 0.20C and 0.10C per decade for Dhaka, Jessore and Chandpur, respectively, during the dry season (November-May). In contrast, Bogra has a decreasing trend of 0.20C per decade. Minimum temperature has increasing trends of 0.30C, 0.20C, 0.20C and 0.10C per decade at Dhaka, Jessore, Bogra and Chandpur, respectively. The relative humidity has increasing trends at four stations in all 10-day periods of the dry season. The average increasing trends are 0.9%, 2.5%, 3.0% and 1.4% per decade at Dhaka, Jessore, Bogra and Chandpur, respectively. The other important climatic variable is the sunshine hour which has decreasing trends in all 10-day periods at the four stations. The average decreasing trends at Dhaka, Jessore, Bogra and Chandpur stations are 0.7, 0.5, 0.5 and 0.7 hours per decade, respectively. Wind speed has both decreasing and increasing trends depending on the stations. The average decreasing trends in wind speed at Dhaka and Chandpur are 15.8 and 40.8 km/day per decade, respectively. The average increasing trends in wind speed are 5.5 km/day and 1.1 km/day per decade at Jessore and Bogra, respectively. From the trend analysis of climatic variables at four stations, it is found that sunshine hour has decreasing trend and relative humidity, maximum temperature and minimum temperature have increasing trends.

 

The combined effect of the trends of above climatic variables on ET0 and net irrigation requirement (NIR) of Boro rice, which is the staple crop in Bangladesh, are then evaluated. The ET0 is found to have decreasing trends at all stations. The decreasing trends are 0.2, 0.2, 0.1 and 0.3 mm/day per decade (10 years) at Dhaka, Jessore, Bogra and Chandpur, respectively, during the dry season. The average decrease of ET0 from 1961 to 2007 is found to be about 23%, 25%, 8% and 33% at Dhaka, Jessore, Bogra and Chandpur, respectively. The net irrigation requirements (NIR) for Boro rice were estimated from rice evapotranspiration and rainfall data. Decreasing trends in NIR of 0.1, 0.1, 0.1 and 0.4 mm/day per decade at Dhaka, Jessore, Bogra and Chandpur stations, respectively, are found. Seasonal mean NIR of 1991-2007 is found to be lower than that of 1961-1975.

 

It appears from this study that the combined effect of the climatic variables of the four stations is the decreasing trends of ET0 and NIR. Besides, the rainfall has increasing trends at the four stations which also contribute to the decreasing trend in NIR. Though the temperatures have increasing trends which should increase ET0 and NIR, the effects of other variables are more dominating than that of temperatures. The findings of this study convey a clear message to the policy and decision makers and water managers that the irrigation sector would not be adversely affected due to climate change. These findings are in contrary to the general belief and reported modeling results which state that due to climate change water requirement for irrigation would increase.

 

 

 

 

 

 

 

Thesis title:

Assessment of Opportunity and Adverse Impact of Wastewater Reuse in Peri-Urban Areas of Rajshahi

 

Name of the student:

            Uthpal Kumar

 

Name of the Supervisor:

            Dr. M. Shah Alam Khan

 

Date of award of  M.Sc.:

            December 27, 2008.

 

Abstract:

            Untreated municipal wastewater is being traditionally used for agriculture by the farmers in the peri-urban areas of Rajshahi city, located in the drought-prone north-western part of Bangladesh. This study was carried out to assess the benefits and adverse impacts of wastewater reuse in the peri-urban areas of Rajshahi. Social acceptance and feasibility of a long term institutional arrangement was also analyzed in this study. Questionnaire surveys were conducted to study farmers’ perception and responses regarding the agricultural, economic, social, environmental and health issues. Also, a total of 12 wastewater and groundwater samples were collected from the study sites for water quality analysis. Analysis results show that most of the water quality parameters expect BOD, do not exceed the WHO recommended limit for irrigation. The most important benefits of wastewater reuse have been found as the availability of wastewater all over the seasons, and reduced chemical fertilizer requirement. Yield and economic return have been found to be higher at the study site than those at the control site. Cropping intensity is also found to be higher at the study site than that at the control site. On the other hand, the potential risks of wastewater reuse have been found to include increased pest attacks and crop diseases, and disease incidents among the farmers. About 25% respondents at the wastewater reuse site reported health problems such as allergy and skin diseases. They also commented that mainly clinical and industrial wastewater is causing these health problems. Local residence reported that wastewater spread over agricultural lands pose significant odor problem. The farmers reported that the crops grown with wastewater irrigation are socially acceptable as they do not face any difficulties to sell them in the market and even from fields. Key informant interviews indicate that a long term institutional arrangement of wastewater reuse is feasible in the study region.

 

 

 

 

 

 

 

Thesis title:

EROSION OF LEFT BANK OF THE PADMA RIVER AT MAWA-DIGHIRPER REACH AND ITS SOCIO-ECONOMIC IMPACT

 

Name of the student:

            MOHAMMAD ARIFUR RAHMAN

 

Name of the Supervisor:

            Dr. Md. Munsur Rahman

 

Date of award of M.Sc.:

            July 2008

 

Abstract:

            The Padma River is highly dynamic and meander in nature. Bank erosion severely affects the socioeconomic condition of the affected reach and not only causes suffering to the people living along its course but also national losses due to loss of cultivated land, settlements, commercial centers and infrastructures. The present research tries to understand the bank erosion of Mawa- Dighirper reach and its present and future socioeconomic impact.

In the present study, a large number of good quality digital data have been prepared from satellite imageries and these data are used to evaluate the channel shifting in the study reach.

The income level of about 70 percent respondents has become less due to change in their working environment. After displacement 28% became day labor, about 16% of the affected are adopted tampo and bus driving, 16% started to work in the garments and cold storage factories.

A total of 78 percent of the households reported having been displaced by erosion at least once; out of them, 80 percent household reported multiple displacements. Eighty eight percent affected household migrated and resettled at the adjacent villages and unions. The affected people have a tendency and attitude to remain close to their homestead, relatives and surroundings.

Most of the School going children gave up their studies forever due to school shift.  About 66 percent of the respondent reported that the educational facilities were deteriorated.

The sinuosity of the recent active bend is 1.02. A Hickin and Nanson type empirical model for the estimation of bank erosion rate was tested in the present study reach. It was observed that the co-efficient of erosion and exponent values for positive trend are 229 and 0.71, respectively and the co-efficient of erosion and exponent values for negative trend are 1280 and 1.77, respectively.

 

 

 

 

 

 

Thesis title:

WATER MANAGEMENT OF INTEGRATED RICE-FISH FARMING IN INUNDATED FLOODPLAINS OF BALAJTALA-KALMADANGA SUBPROJECT

 

Name of the student:

            Md. Sydur Rahman

 

Name of the Supervisor:

            Dr. Mashfiqus Salehin

 

Date of award of  M.Sc.:

            June 25, 2008.

 

Abstract:

            The burning issues that currently surround the countries in South Asia are food security and ecosystem security. While food security is of paramount importance, protein requirement is also an important issue, since many of the rural children and older people suffer from severe protein malnutrition. In Bangladesh, fish is the only source of free animal protein for the poorer section of the community. One of the potential scopes for improving fish production in Bangladesh is to integrate aquaculture with rice farming, and considerable scopes are there to exercise such practice in inundated rice fields during the monsoon season through local community based water management.

 

In this study, the potential of integrated rice-fish farming was explored in inundated areas of a small water management project, namely, Balajtala-Kalmadanga Subproject in Gopalganj district of the Southwest region of Bangladesh. The study followed an interdisciplinary approach through technical assessments as well as application of participatory tools to address different dimensions of integrated rice-fish farming in the study area, including physical, socio-economic, institutional and environmental aspects.   Using a set of criteria and indicators, the system was evaluated from a sustainability point of view; for example, whether the existing physical systems are suitable for integrated farming practice, whether the new system is able or have the potential to have a positive impact on the socio-economic condition, whether the system will be environmentally sound, and what kind of management infrastructure and water management system are required for the integrated farming system to be sustainable over long periods.

 

The water management infrastructures in the project area were found to be conducive to the adoption of the new farming system.  Desired water levels required for minimization of rice yield reduction and increasing favorable condition for fish culture were analyzed, which can be met from the available water in the study area. Results indicate that standing water depth up to 50% of plant height is recommended during the different growing stages of rice that maximizes yield and increases the favorable condition for fish culture. Benefits obtained by the community were more than that they obtained in previous years from rice monoculture. However, potential of further enhancement of benefits are there in the study area. Since introduction of fish culture is still in an experiment stage in the study area, the existing fish yield is relatively on the lower side at 0.10 ton/ha. However, there are immense potentials to increase the yield many folds by increasing the stocking of fish fingerlings feasible for the study area. With increased stocking of fish fingerlings, the simulated fish yield was 6.20 ton/ha, which is much higher than the present yield. Full implementation of the project by Local Government Engineering Department (LGED) will allow more area to be brought under cultivation during Kharif-II season. The existing benefit-cost ratio (BCR) for rice-only is 1.61 compared to 1.78 in the projected post-project condition. Integration of fish with rice will increase the BCR manifolds; the simulated BCR for rice plus fish cultivation system is 5.11 compared to the existing ratio of 2.18.

 

 The integrated farming system was found to be socially acceptable. The quality of soils was enhanced with the introduction of fish in inundated rice field, which is favorable for Boro crops to be followed in the field in the dry season. Organic carbon, organic matter and nitrogen content in soil after fish cultivation in rice field recorded about 2, 3 and 19 times higher, respectively than that of only rice cultivation system. However, no remarkable impacts on soil quality were found in PH, phosphorous and potassium content between with and without rice-fish cultivation system. The integrated farming system improved pest management and weed control, and did not negatively impact water quality, indigenous capture fisheries and biodiversity.

 

There are some shortcomings in the management process with the integrated system, including community-based fish farming through Water Management Co-operative Association with fair distribution of shares and benefits among landowner, landless, traditional fisher men and women. The study suggests some management processes, and anticipates that these will pave the way for more motivation and social acceptability among the community members with disparate socio-economic status, which in turn will help sustain the system.

 

The results conclude that community-based fish culture approach in the study area has the potential of being technically feasible, economically profitable, environmentally sound, and socially acceptable.

 

 

 

 

 

 

Thesis title:

impacts of climate change on command area development of teesta barrage project

 

Name of the student:

            Md. Moshiur Rahman

Name of the Supervisor:

            Dr. Abul Fazal M. Saleh

Date of award of  M.Sc.:

            September, 2008.

Abstract:

            The impacts of climate change on agricultural food production are global concerns, and they are very important for Bangladesh. Climate change may have repercussions on the command area development of Phase-II of the Teesta Barrage Project (TBP), which is now at the implementation stage. This study was accomplished to find out the possible effects of climate change on TBP and the possible mitigation measures. A farmers’ survey was conducted to assess the farmers’ awareness about climate change and possible mitigation measures. Discussion meetings with officials of TBP were also held to assess the preparation of the project authority in mitigating the adverse effects of climate change.

 

In this study, meteorological data were taken from the prediction of Hadley Centre’s generated two climate models (HadCM3 and PRECIS) with A2 and B2 scenarios and the flow of Teesta river was taken from the outputs of CLASIC project, for the future horizons of 2025 and 2050. From the analysis, it was found that due to climate change the future crop water requirement would increase by 2.8% to 9.2% and 1.7% to 21.0% for Phase-I and for Phase-II by 4.1% to 10.3% and 3.1% to 14.9% for the projection years of 2025 and 2050, respectively compared to the baseline period of 1990. Similarly, for the same projection years, the rainfall would decrease by 0.2% to 8.6% and 1.6% to 19.0% for Phase-I and for Phase-II by 7.0% to 23.7% and 3.0% to 15.1%. As a result, the future flow of Teesta river would decrease during the critical period of October by 11.1% to 20.1%, 28.9% to 31.4% and 23.9% to 30.6% in 2025 and by 5.4% to 24.8%, 15.3% to 32.8% and 12.2% to 23.0% in the project year of 2050 for the 1st, 2nd and 3rd decades, respectively. During the 1st and 2nd decades of October the scheme water requirement may exceed the maximum capacity (283 m3/sec) of the canal head regulator. All models showed that with the present cropping pattern the TBP may face problem to meet the future increased demand due to the adverse effects of climate change. It should be noted that, because of coarse resolution, variability and uncertainty in assumptions made and scenarios developed, the results of the climate change models are only indicative.

 

From the technical feasibility analysis of possible mitigation measures it was revealed that by shifting to earlier transplanting dates or by introducing short duration Aman variety, it is possible to evade the shortfall in discharge of Teesta river during the critical period of October. Keeping the present transplanting schedule, augmentation of the water availability for irrigation during October is feasible either by rainwater harvesting through on-farm reservoir or by internal river linking to the TBP.

 

From the farmers’ survey it was evident that they are totally unaware of global warming and climate change but they have observed some changes in their local climate. When asked about the adoption of technically feasible climate change mitigation options, the on-farm reservoir was unacceptable to them as it takes away land permanently out of production. Farmers were not very enthusiastic about either earlier transplanting or short duration variety but would adopt them if necessary. The project officials believe that the future climate change scenario would not be as severe as predicted by the models due to spatial variation of climate. At present they have no preparation to mitigate the adverse impacts of climate change but would opt for flow augmentation from the internal rivers if needed.

 

 

 

 

 

 

 

Thesis title:

IMPACTS OF THE KAWRAID RIVER RUBBER DAM PROJECT ON AGRICUTURAL PERFORMANCE AND POVERTY

 

Name of the student:

            ABU JAFAR MD. SALEH

 

Name of the Supervisor:

            Dr. M. Shahjahan Mondal

 

Date of award of  M.Sc.:

            May 03, 2008.

 

Abstract:

            The Kawraid River Rubber Dam Project (KRRDP) of Gazipur District was commissioned by the Local Government Engineering Department (LGED) in 2000-01 and has been in operation since 2002-03 irrigation season. The project has the total irrigation coverage of 1232 ha for Boro rice cultivation. The objectives of the present study are to evaluate the impact of the KRRDP on the agricultural performance and to assess the impact of this project on poverty. Two study sites have been selected, i.e., the With Project (WP) area and the Without Project (WOP) area. The irrigation season 2000-01 has been considered as the base year and 2006-07 as the current year. The agricultural performance has been evaluated by using the agricultural indicators. The poor household has been identified by using the modified self-assessment method. A multiple linear regression model has been used to find out the relationship between poverty and its predictors. Results of the study show that the average Boro rice yield per ha in current year is about 30% higher in the WP area; whereas, it is only 7% higher in the WOP area than that of the base year. The production performance of the WP area is quite higher (0.87) in 2006-07 than that of 2000-01 (0.42), but the difference is not significant in the WOP area (0.54 and 0.61 in 2000-01 and 2006-07 irrigation seasons, respectively). The net income (Tk./ha) is 180% higher in the WP area; whereas, it is only 3.62% higher in the WOP area in 2006-07 irrigation season compared to that of the base year. The study reveals that 28.89% and 33.33% people were staying below the poverty line in the WP and WOP areas respectively in 2001, whereas the similar figures of the respective areas have decreased to 17.78% and 26.67% in 2007. Actually the irrigation intervention with the KRRDP reduces poverty by 4.45%. For each percentage increase in irrigated agricultural land, poverty reduction is found to be about 0.20% in the WP area. Multiple regression results show that the income from Boro rice has a large influence on poverty reduction of the WP area. Both the WP and WOP areas also exhibit a strong relationship between education and poverty. Therefore, the study can be summed up as: irrigation intervention might have played an important role in leveling up the production performances in the area which could have triggered an improvement in the local livelihoods; thus contributing to the eradication of poverty.

 

 

 

 

 

 

Thesis title:

ASSESSMENT OF DROUGHT OF 2006 AND ITS MANAGEMENT BY THE   FARMERS IN RAJSHAHI DISTRICT

 

Name of the student:

            Mst. Irin Parvin

 

Name of the Supervisor:

            Dr. Abul Fazal M. Saleh

 

Date of award of  M.Sc.:

            30th  April, 2008.

 

Abstract:

            Although the droughts are common in the north-west region of the country, especially in the Barind Tract, not much is known about the mitigation measures adopted by the farmers. This study was accomplished with a view to assess the drought of T. Aman season of 2006 and farmers’ management practices of drought alleviation at Godagari Upazila in Rajshahi district. The time and extent of drought was calculated by using the water balance and relative water supply methods. The probability analysis of rainfall and crop water requirement was carried out by Gamma distribution. Drought affected yield was estimated by using crop production function. A farmers’ survey was conducted to gain information on drought affected yields, farmers’ management practices of drought alleviation and related socio-economic issues.

 

From the water balance analysis, it is found that three droughts occurred during the T. Aman season of 2006. During vegetative stage one drought of six days duration, during reproductive stage one drought of four days duration and in ripening stage one drought of sixteen days duration occurred. The average values of RWS were 0.60 in vegetative stage, 0.66 in reproductive stage and 0 in ripening stage. The average value of RWS was 0.45 in 2006 T. Aman season. Both the analyses showed that severe drought occurred during the ripening stage of T. Aman in 2006.

 

From probability analysis, it was observed that the probability of rainfall that occurred during the T. Aman season of 2006 is about 20% (once in about five years). Probability of meeting the crop water requirement from rainfall is 67% (about seven times in 10 years).

 

From the farmers’ survey, it was revealed that during 2006, 75% of the farmers used supplementary irrigation for T. Aman production. The average yield was 4.05 M. ton/ha for the farmers who provided supplementary irrigation and drought affected yield was 1.64 M. ton/ha. The drought affected yield calculated from crop production function was 1.65 M. ton/ha. Actual drought affected area during 2006 T. Aman season was estimated as 4272 hectares which was about 13% of the Aman cultivated area. The benefit-cost ratio (BCR) of supplementary irrigation from surface water and ground water were 4.10 and 5.88, respectively. The farmers’ survey showed that supplementary irrigation was the only socially acceptable management practice of drought alleviation in the study area. The study reveled that due to the application of supplementary irrigation, droughts do not severely affect the T. Aman yield.  

 

 

 

 

 

 

Thesis title:

Assessment of ecological health status in selected haors with different degrees of interventions using fish indicators

 

Name of the student:

            S.M. Sanaul Kafi

 

Name of the Supervisor:

            Dr. Mashfiqus Salehin

 

Date of award of  M.Sc.:

            April 19, 2008.

 

Abstract:

            Haors are very important habitats for the unique and dynamic ecosystems, which have immense productive or ecological value. Importantly, haors provide suitable habitats for fisheries, a major component of the ecological resources.  However, anthropogenic interferences, e.g. wetland encroachment and exploitation pressure, and water management infrastructures are causing decline of wetland habitats, especially during the dry season.  Water management interventions bring about changes in natural systems of haors, and hence the impact of partial flood protection on the ecosystem of the haors is emerging as a significant concern.

 

The study examined the ecosystem of three selected haors subject to varying physical effects of water management infrastructure.  Fish has been selected as an indicator for ecosystem as fishes are sensitive to many changes in natural water quality and habitat structure caused by anthropogenic or by natural causes. Based on a set of pre-determined criteria, a total of three haors were selected, which represented three distinct physical characteristics: a relatively undisturbed state (Chaptir haor), a moderately intervened state (Tangua haor), and an extensively intervened state (Baram haor). A range of Participatory Rural Appraisal (PRA) tools (e.g. resource mapping, FGDs) were used in the study to obtain data relating to the status of the physical system of the haors and the status of fisheries ecosystem.

 

The findings from the field surveys showed that migration routes and fish habitat areas have been impacted to different degrees in the three haors by water management infrastructures. Fish migration routes are better in Chaptir haor, followed by Tangua haor.   Migration routes in Baram haor are the worst. Habitat depths, e.g. depths of the river, khals and beels are highest in Chaptir haor, followed by Tangua haor.  Habitat depths in Baram haor are the lowest.  The impact of water management interventions has also been reflected in the declines in fish catch compared to a period 10 years ago.

 

A scoring and ranking method was used for analyzing habitat wise fish composition data obtained from the field survey.  This exercise yielded three species (Rui, Catla, and Boal) which are indicative of different status of ecosystem health in the haors.     

 

 

 

 

 

 

Thesis title:

RELATIONSHIP BETWEEN SALINITY AND CROP PRODUCTION   IN DIFFERENT HYDROLOGICAL REGIMES DOWNSTREAM OF MUHURI REGULATOR

 

Name of the student:

            A. K. M. Alauddin Chowdhury

 

Name of the Supervisor:

            Dr. Md. Rezaur Rahman

 

Date of award of  M.Sc.:

            29th September, 2007.

 

Abstract:

            A large landmass was formed at the downstream of Feni river due to the construction of Muhuri regulator at a cross dam in Mirsarai upazila of Chittagong district. But this land is more vulnerable to storm and tidal surges leading to saline water intrusion. The study site was selected from this area to investigate the relationship between salinity and crop production. Soil samples were collected from different hydrological regimes such as old protected area, new protected area, unprotected area and affected area. Samples were taken from topsoil, subsoil and substratum at each location in both aman and rabi seasons. Crop yield of the sampling plots were recorded through farmer’s interview. It was found that, salinity of study area was less than 4 dS/m both in aman and rabi seasons. Rice is a semi-tolerant crop (can tolerate salinity up to 4 dS/m), so no significant relationship between soil salinity and rice yield was found in aman season. In rabi season, salinity was also found less than 4 dS/m except in unprotected area. A positive correlation was found between soil salinity and khesari yield, which was found to be significant in unprotected area. Water salinity inside the cross dam was around 0.1 dS/m (rabi season), which is considered excellent for irrigation. But outside the cross dam it ranged in between 4.8-5.4 dS/m in aman season and 12.4-20.8 dS/m in rabi season, which was extremely toxic for irrigation.

 

Although soil salinity permits HYV rice cultivation in aman season, water logging was reported by farmers as the main constraint to HYV rice cultivation in the study area. The farmers opined that HYV rice in aman season can be cultivated by improving water logging problems of Godashara canal in old protected area, by removing boundaries of fish pond in new protected area, construction of an embankment on the eastern side of Feni river in unprotected area and cultivating submergence tolerant variety in affected area.

 

HYV rice in boro season can be cultivated in old and new protected area by utilizing Feni river water inside the Muhuri regulator and closure dam for irrigation purpose. But it can not be cultivated due to salinity problem (>4 dS/m) in unprotected area and lack of irrigation water in affected area. But in these areas khesari can be grown successfully by utilizing residual soil moisture.