Khalid Mahmud - Academia.edu (original) (raw)
Papers by Khalid Mahmud
Modeling Earth Systems and Environment, Jan 18, 2018
Fecal sludge management is an emerging issue in urban sanitation. Access to sewage network is lim... more Fecal sludge management is an emerging issue in urban sanitation. Access to sewage network is limited in Dhaka; therefore people construct septic tanks and different forms of unhygienic latrines to fulfill their basic sanitary needs. The main objective of this study was to evaluate the effectiveness of the Vacutug pit latrine exhausting technology considering the perspectives of the technical experts, operators and consumers. With increasing rapid growth, Dhaka city may reach up to 25 million people by 2025. The slum population is growing massively and with it sanitation problems. A major problem is one of sanitation facilities, especially for the urban poor but a further and equally pressing one is that of the emptying, transportation and treatment of fecal sludge from latrines. In this paper, the operational, financial and management issues surrounding Vacutug are introduced. The research focused on the experiences from three initiatives (Mirpur, Mohammadpur and Kuril in Dhaka) to gain a greater insight into key features of straight awareness related to participatory planning and community involvement in decision-making, decentralized management arrangements for operation and maintenance, application and operation of decentralized technologies; Financing arrangements and economics of decentralized initiatives.
Atmosphere, 2022
Finding significant trends in hydroclimate time series has been deemed an essential task in numer... more Finding significant trends in hydroclimate time series has been deemed an essential task in numerous studies. Despite the existence of various trend detection methods, statistical significance is mostly examined for linear trends and related to the meaningfulness of the found trends. We wish to draw attention to a more general definition of meaningful trends by cross-referencing not only linear but also smoothing techniques. We apply linear regression (LR) and two smoothing techniques based on regularized minimal-energy tensor-product B-splines (RMTB) to the trend detection of standardized precipitation index (SPI) series over Taiwan. LR and both RMTB-based methods identify an overall upward (wetting) trend in the SPI series across the time scales in Taiwan from 1960 to 2019. However, if dividing the entire time series into the earlier (1960–1989) and later (1990–2019) sub-series, we find that some downward (drying) trends at varied time scales migrate from southcentral–southwestern...
Impact assessment of wastewater on soil is important to diagnose the potential of wastewater irri... more Impact assessment of wastewater on soil is important to diagnose the potential of wastewater irrigation. By taking this idea into consideration, an experiment was conducted to investigate the chemical and solute-transport properties of soils collected from wheat fields irrigated with sugar mills' wastewater at North Bengal Sugar Mill (NBSM) and Faridpur Sugar Mill (FSM) of Bangladesh. Soil samples were collected from experimental sites where wheat was grown under both irrigation and fertilizer treatments. The split-plot design with three replications of irrigation (main plot) and fertilizer (sub-plot) were used. Irrigation and fertilizer treatments were defined as I 1 = irrigation with fresh water, I 2 = irrigation with mixed water (fresh water: wastewater = 1:1) and I 2 = irrigation with wastewater; F 1 = Full dose fertilizer, F 2 = Half dose fertilizer and F 3 = No application of fertilizer. Soil samples were chemically analyzed to find their chemical properties and a breakthr...
Impact assessment of wastewater on soil is important to diagnose the potential of wastewater irri... more Impact assessment of wastewater on soil is important to diagnose the potential of wastewater irrigation. By taking this idea into consideration, an experiment was conducted to investigate the chemical and solute-transport properties of soils collected from wheat fields irrigated with sugar mills’ wastewater at North Bengal Sugar Mill (NBSM) and Faridpur Sugar Mill (FSM) of Bangladesh. Soil samples were collected from experimental sites where wheat was grown under both irrigation and fertilizer treatments. The split-plot design with three replications of irrigation (main plot) and fertilizer (sub-plot) were used. Irrigation and fertilizer treatments were defined as I1 = irrigation with fresh water, I2 = irrigation with mixed water (fresh water: wastewater = 1:1) and I2 = irrigation with wastewater; F1 = Full dose fertilizer, F2 = Half dose fertilizer and F3 = No application of fertilizer. Soil samples were chemically analyzed to find their chemical properties and a breakthrough exp...
Theoretical and Applied Climatology, 2021
Understanding teleconnections of a region's climate can be beneficial to seasonal outlooks an... more Understanding teleconnections of a region's climate can be beneficial to seasonal outlooks and hydro-climate services. This study aims at analyzing the teleconnections of seasonal rainfall over Bangladesh with selected climate indices, including El Niño/Southern Oscillation (ENSO), Indian Ocean Dipole (IOD), Pacific Decadal Oscillation (PDO), and Atlantic Multidecadal Oscillation (AMO) indices. Rainfall data spanning from 1965–2017 in the seven hydrological regions are used to derive three seasonal rains, namely the pre-monsoon (March–May), monsoon (June–September), and post-monsoon (October and November) rains, for correlation- and wavelet coherence (WC)-based teleconnection analyses. Among the three seasonal rains, the post-monsoon rain shows the negative correlations, strongest with the IOD and ENSO indices. Correlations between the pre-monsoon/monsoon rain and climate indices are subject to notable spatial and temporal variations. For instance, correlations between the pre-m...
Animal Reproduction Science, 2019
The study aim was to estimate gestational age (GA), expected parturition date (EPD) and growth ra... more The study aim was to estimate gestational age (GA), expected parturition date (EPD) and growth rate by determining fetal trunk diameter (TD). Effects of fetal-dam pelvis alignment and in utero fetal position at time of ultrasonography (UG) on fetal numbers and sex determination were also studied. Trans-abdominal UG (3-6.5 MHz) was conducted on 37 ewes with known breeding dates from Days 25-120 of pregnancy. Errors in GA and EPD were studied using an equation in the same ewes at their successive breeding when date of breeding was unknown. There were four equations, Y = 1.28861X+32.656 (R 2 = 0.92), for Indigenous; Y = 1.2603X+38.075 (R 2 = 0.85), for Indigenous × Garole; and Y = 0.8932X+45.916 (R² = 0.99), for Garole fetuses; and the equation, Y = 1.3565X + 32.604 (R 2 = 0.94), independent of breed were computed to estimate GA and the relationship between GA and TD of different breeds. The error in estimated GA and EPD using these four equations was determined and there was comparison with the data collected using US and the previously described equations. Results indicate there was the greatest (P < 0.01) error for GA and EPD values using the US TD equation for all breeds. There was the least error in estimated EPD using the breed specific equations. Error in the sex determination was 4.8 % and fetal number determination was 16.7 % with singleton and 7.7 % twin fetuses. The results indicate there is a breed specific fetal TD that is useful for predicting GA in sheep.
Fundamental and Applied Agriculture, 2016
Late crop establishment is a major problem for successful harvest of rabi crops in saline coastal... more Late crop establishment is a major problem for successful harvest of rabi crops in saline coastal zone of Bangladesh. Identification of appropriate crop establishment techniques is also important to overcome the problem. Because selection of proper crop establishment method is the first step towards earlier establishment of rabi crops. An experiment was conducted during December 2013 to May 2014 at Kismat Fultola village in Khulna district to identify appropriate crop establishment techniques for early establishment of wheat. Crop establishment methods tested were-C1: seeds sown after row-spading at soil moisture in between saturation and field capacity, C2: seeds sown in furrows at soil moisture in between saturation and field capacity, and C3: seeds sown on the surface of saturated soil with straw mulch. There were three irrigation regimes-I1 = No irrigation (rainfed), I2 = One irrigation at 15-20 days after emergence (DAE), I3 = Two irrigations at soil suction values of 50 kPa and 70-90 kPa, respectively at 37.5 cm soil depth. Early planting of wheat was 9 December 2013. The establishment techniques and planting dates showed different degrees of influence on the crops. The highest grain yield was obtained in C3 (1.44 t ha-1) and the lowest was found in C1 (1.15 t ha-1). In case of irrigation treatments, the grain yield in I3 (1.49 t ha-1) and I2 (1.35 t ha-1) was significantly higher than that in I1 (1.04 t ha-1). The highest yield (1.49 t ha-1) was obtained from the two irrigations and straw mulch treated plot, even though the yield was less compared to standard wheat yield in that region (2.0-3.0 t ha-1). This is because of less plant density due to uneven germination, damage/death of plants after germination and possibly leaching of the top-dressed nitrogen fertilizer out of root zone through cracks. The results demonstrate that early establishment of rabi crops in the coastal region is possible, which is highly desirable for improving food security and livelihoods of the climate-vulnerable coastal communities of Bangladesh.
Progressive Agriculture, 2014
This paper describes a rainfall-runoff simulation study, conducted in a laboratory to investigate... more This paper describes a rainfall-runoff simulation study, conducted in a laboratory to investigate surface runoff characteristics, verify unit hydrograph assumption and investigate the nature of the recession constant. A hydrology bench consisting of a metallic tray with an over head sprinkler system was used for this study. The metallic tray with soil bed and a river network acted as a small catchment. The over head sprinkler system consisting of spray nozzles acted as rainfall simulator. Different rainfall intensities and durations were taken as the treatments for the experiments. Surface runoff volume was collected at 10 secondly pulses of time in each experiment. Collected data were then processed and analyzed to explain the results. Unit hydrographs were developed from the surface runoff hydrographs for different rainfall durations and intensities. Recession constant K was calculated from the recession limb of each surface runoff hydrograph by optimization. Investigations show t...
Journal of the Bangladesh Agricultural University, 2018
Research on temperature extremes deserves more importance because it reacts sensitively to climat... more Research on temperature extremes deserves more importance because it reacts sensitively to climate change. As elsewhere across the world, Bangladesh has already become a victim of temperature extremes. Hence, this study was conducted to assess the trends and variability of 11 temperature-related extreme indices based on daily maximum (TX) and daily minimum (TN) temperature recorded at Rajshahi and Barisal over the period 1976–2015. The indices were calculated on annual basis and their average annual and decadal trends were evaluated by non-parametric Mann-Kendall test and Sen’s slope estimate. Significant (p ≤ 0.01) upward trend was observed in some of the hot extremes, such as SU35: number of days with TX > 35°C and TR25: number of days with TN > 25°C, indicating that the number of days and nights with extreme hot temperature are increasing in both sites. Significant decreasing rate (-0.308 day/year) of SU25: number of days with TX > 25°C and increasing rate (1.00 day/year...
Journal of Bangladesh Agricultural University, 2020
Modeling Earth Systems and Environment, Jan 18, 2018
Fecal sludge management is an emerging issue in urban sanitation. Access to sewage network is lim... more Fecal sludge management is an emerging issue in urban sanitation. Access to sewage network is limited in Dhaka; therefore people construct septic tanks and different forms of unhygienic latrines to fulfill their basic sanitary needs. The main objective of this study was to evaluate the effectiveness of the Vacutug pit latrine exhausting technology considering the perspectives of the technical experts, operators and consumers. With increasing rapid growth, Dhaka city may reach up to 25 million people by 2025. The slum population is growing massively and with it sanitation problems. A major problem is one of sanitation facilities, especially for the urban poor but a further and equally pressing one is that of the emptying, transportation and treatment of fecal sludge from latrines. In this paper, the operational, financial and management issues surrounding Vacutug are introduced. The research focused on the experiences from three initiatives (Mirpur, Mohammadpur and Kuril in Dhaka) to gain a greater insight into key features of straight awareness related to participatory planning and community involvement in decision-making, decentralized management arrangements for operation and maintenance, application and operation of decentralized technologies; Financing arrangements and economics of decentralized initiatives.
Atmosphere, 2022
Finding significant trends in hydroclimate time series has been deemed an essential task in numer... more Finding significant trends in hydroclimate time series has been deemed an essential task in numerous studies. Despite the existence of various trend detection methods, statistical significance is mostly examined for linear trends and related to the meaningfulness of the found trends. We wish to draw attention to a more general definition of meaningful trends by cross-referencing not only linear but also smoothing techniques. We apply linear regression (LR) and two smoothing techniques based on regularized minimal-energy tensor-product B-splines (RMTB) to the trend detection of standardized precipitation index (SPI) series over Taiwan. LR and both RMTB-based methods identify an overall upward (wetting) trend in the SPI series across the time scales in Taiwan from 1960 to 2019. However, if dividing the entire time series into the earlier (1960–1989) and later (1990–2019) sub-series, we find that some downward (drying) trends at varied time scales migrate from southcentral–southwestern...
Impact assessment of wastewater on soil is important to diagnose the potential of wastewater irri... more Impact assessment of wastewater on soil is important to diagnose the potential of wastewater irrigation. By taking this idea into consideration, an experiment was conducted to investigate the chemical and solute-transport properties of soils collected from wheat fields irrigated with sugar mills' wastewater at North Bengal Sugar Mill (NBSM) and Faridpur Sugar Mill (FSM) of Bangladesh. Soil samples were collected from experimental sites where wheat was grown under both irrigation and fertilizer treatments. The split-plot design with three replications of irrigation (main plot) and fertilizer (sub-plot) were used. Irrigation and fertilizer treatments were defined as I 1 = irrigation with fresh water, I 2 = irrigation with mixed water (fresh water: wastewater = 1:1) and I 2 = irrigation with wastewater; F 1 = Full dose fertilizer, F 2 = Half dose fertilizer and F 3 = No application of fertilizer. Soil samples were chemically analyzed to find their chemical properties and a breakthr...
Impact assessment of wastewater on soil is important to diagnose the potential of wastewater irri... more Impact assessment of wastewater on soil is important to diagnose the potential of wastewater irrigation. By taking this idea into consideration, an experiment was conducted to investigate the chemical and solute-transport properties of soils collected from wheat fields irrigated with sugar mills’ wastewater at North Bengal Sugar Mill (NBSM) and Faridpur Sugar Mill (FSM) of Bangladesh. Soil samples were collected from experimental sites where wheat was grown under both irrigation and fertilizer treatments. The split-plot design with three replications of irrigation (main plot) and fertilizer (sub-plot) were used. Irrigation and fertilizer treatments were defined as I1 = irrigation with fresh water, I2 = irrigation with mixed water (fresh water: wastewater = 1:1) and I2 = irrigation with wastewater; F1 = Full dose fertilizer, F2 = Half dose fertilizer and F3 = No application of fertilizer. Soil samples were chemically analyzed to find their chemical properties and a breakthrough exp...
Theoretical and Applied Climatology, 2021
Understanding teleconnections of a region's climate can be beneficial to seasonal outlooks an... more Understanding teleconnections of a region's climate can be beneficial to seasonal outlooks and hydro-climate services. This study aims at analyzing the teleconnections of seasonal rainfall over Bangladesh with selected climate indices, including El Niño/Southern Oscillation (ENSO), Indian Ocean Dipole (IOD), Pacific Decadal Oscillation (PDO), and Atlantic Multidecadal Oscillation (AMO) indices. Rainfall data spanning from 1965–2017 in the seven hydrological regions are used to derive three seasonal rains, namely the pre-monsoon (March–May), monsoon (June–September), and post-monsoon (October and November) rains, for correlation- and wavelet coherence (WC)-based teleconnection analyses. Among the three seasonal rains, the post-monsoon rain shows the negative correlations, strongest with the IOD and ENSO indices. Correlations between the pre-monsoon/monsoon rain and climate indices are subject to notable spatial and temporal variations. For instance, correlations between the pre-m...
Animal Reproduction Science, 2019
The study aim was to estimate gestational age (GA), expected parturition date (EPD) and growth ra... more The study aim was to estimate gestational age (GA), expected parturition date (EPD) and growth rate by determining fetal trunk diameter (TD). Effects of fetal-dam pelvis alignment and in utero fetal position at time of ultrasonography (UG) on fetal numbers and sex determination were also studied. Trans-abdominal UG (3-6.5 MHz) was conducted on 37 ewes with known breeding dates from Days 25-120 of pregnancy. Errors in GA and EPD were studied using an equation in the same ewes at their successive breeding when date of breeding was unknown. There were four equations, Y = 1.28861X+32.656 (R 2 = 0.92), for Indigenous; Y = 1.2603X+38.075 (R 2 = 0.85), for Indigenous × Garole; and Y = 0.8932X+45.916 (R² = 0.99), for Garole fetuses; and the equation, Y = 1.3565X + 32.604 (R 2 = 0.94), independent of breed were computed to estimate GA and the relationship between GA and TD of different breeds. The error in estimated GA and EPD using these four equations was determined and there was comparison with the data collected using US and the previously described equations. Results indicate there was the greatest (P < 0.01) error for GA and EPD values using the US TD equation for all breeds. There was the least error in estimated EPD using the breed specific equations. Error in the sex determination was 4.8 % and fetal number determination was 16.7 % with singleton and 7.7 % twin fetuses. The results indicate there is a breed specific fetal TD that is useful for predicting GA in sheep.
Fundamental and Applied Agriculture, 2016
Late crop establishment is a major problem for successful harvest of rabi crops in saline coastal... more Late crop establishment is a major problem for successful harvest of rabi crops in saline coastal zone of Bangladesh. Identification of appropriate crop establishment techniques is also important to overcome the problem. Because selection of proper crop establishment method is the first step towards earlier establishment of rabi crops. An experiment was conducted during December 2013 to May 2014 at Kismat Fultola village in Khulna district to identify appropriate crop establishment techniques for early establishment of wheat. Crop establishment methods tested were-C1: seeds sown after row-spading at soil moisture in between saturation and field capacity, C2: seeds sown in furrows at soil moisture in between saturation and field capacity, and C3: seeds sown on the surface of saturated soil with straw mulch. There were three irrigation regimes-I1 = No irrigation (rainfed), I2 = One irrigation at 15-20 days after emergence (DAE), I3 = Two irrigations at soil suction values of 50 kPa and 70-90 kPa, respectively at 37.5 cm soil depth. Early planting of wheat was 9 December 2013. The establishment techniques and planting dates showed different degrees of influence on the crops. The highest grain yield was obtained in C3 (1.44 t ha-1) and the lowest was found in C1 (1.15 t ha-1). In case of irrigation treatments, the grain yield in I3 (1.49 t ha-1) and I2 (1.35 t ha-1) was significantly higher than that in I1 (1.04 t ha-1). The highest yield (1.49 t ha-1) was obtained from the two irrigations and straw mulch treated plot, even though the yield was less compared to standard wheat yield in that region (2.0-3.0 t ha-1). This is because of less plant density due to uneven germination, damage/death of plants after germination and possibly leaching of the top-dressed nitrogen fertilizer out of root zone through cracks. The results demonstrate that early establishment of rabi crops in the coastal region is possible, which is highly desirable for improving food security and livelihoods of the climate-vulnerable coastal communities of Bangladesh.
Progressive Agriculture, 2014
This paper describes a rainfall-runoff simulation study, conducted in a laboratory to investigate... more This paper describes a rainfall-runoff simulation study, conducted in a laboratory to investigate surface runoff characteristics, verify unit hydrograph assumption and investigate the nature of the recession constant. A hydrology bench consisting of a metallic tray with an over head sprinkler system was used for this study. The metallic tray with soil bed and a river network acted as a small catchment. The over head sprinkler system consisting of spray nozzles acted as rainfall simulator. Different rainfall intensities and durations were taken as the treatments for the experiments. Surface runoff volume was collected at 10 secondly pulses of time in each experiment. Collected data were then processed and analyzed to explain the results. Unit hydrographs were developed from the surface runoff hydrographs for different rainfall durations and intensities. Recession constant K was calculated from the recession limb of each surface runoff hydrograph by optimization. Investigations show t...
Journal of the Bangladesh Agricultural University, 2018
Research on temperature extremes deserves more importance because it reacts sensitively to climat... more Research on temperature extremes deserves more importance because it reacts sensitively to climate change. As elsewhere across the world, Bangladesh has already become a victim of temperature extremes. Hence, this study was conducted to assess the trends and variability of 11 temperature-related extreme indices based on daily maximum (TX) and daily minimum (TN) temperature recorded at Rajshahi and Barisal over the period 1976–2015. The indices were calculated on annual basis and their average annual and decadal trends were evaluated by non-parametric Mann-Kendall test and Sen’s slope estimate. Significant (p ≤ 0.01) upward trend was observed in some of the hot extremes, such as SU35: number of days with TX > 35°C and TR25: number of days with TN > 25°C, indicating that the number of days and nights with extreme hot temperature are increasing in both sites. Significant decreasing rate (-0.308 day/year) of SU25: number of days with TX > 25°C and increasing rate (1.00 day/year...
Journal of Bangladesh Agricultural University, 2020