G. M. Jahid Hasan | Military Institute of Science & Technology (MIST) (original) (raw)

Papers by G. M. Jahid Hasan

Electricity is the pinnacle of human civilization. At present, the growing concerns over signific... more Electricity is the pinnacle of human civilization. At present, the growing concerns over significant climate change have intensified the importance of use of renewable energy technologies for electricity generation. The interest is primarily due to better energy security, smaller environmental impact and providing a sustainable alternative compared to the conventional energy sources. Solar, wind, biomass, tide, and wave are some of the most reliable sources of renewable energy. Ocean approximately holds 2×10 TW of energy and has the largest renewable energy resource on the planet. Ocean energy has many forms namely, encompassing tides, ocean circulation, surface waves, salinity and thermal gradients etc. Ocean tide in particular, associates both potential and kinetic energy. The study is focused on the latter concept that deals with tidal current energy conversion technologies. Tidal streams or marine currents generate kinetic energy that can be extracted by marine current energy de...

World Academy of Science, Engineering and Technology, International Journal of Civil and Environmental Engineering, 2017

Electricity is the pinnacle of human civilization. At present, the growing concerns over signific... more Electricity is the pinnacle of human civilization. At present, the growing concerns over significant climate change have intensified the importance of use of renewable energy technologies for electricity generation. The interest is primarily due to better energy security, smaller environmental impact and providing a sustainable alternative compared to the conventional energy sources. Solar, wind, biomass, tidal, and wave power are some of the most reliable sources of renewable energy. Ocean approximately holds 2 × 103 tW of energy and has the largest renewable energy resource on the planet. Various forms constitute ocean energy namely, encompassing tides, ocean circulation, surface waves, salinity and thermal gradients. Ocean tide in particular, associates both potential and kinetic energy. The study is focused on the latter concept that deals with energy due to tidal current. Tidal currents generate kinetic energy that can be extracted by marine energy devices and converted into tr...

Mangroves are extremely important from the ecological and socio-economic perspectives, but are de... more Mangroves are extremely important from the ecological and socio-economic perspectives, but are degrading at an alarming rate nowadays. Besides direct clearance, hydrological alterations or climatic changes, chemical pollution could be a significant contributor of mangrove degradation. To understand chemical pollution in mangroves, the input and output (mass balance) of pollutants within a region need to be assessed. To identify critical situations that cause high concentrations of contaminants in the mangrove wetland, residence time was defined as the time required for flushing out pollutants from a determined region, and evaluated through numerical modeling. This concept was applied to a pollutant mass balance in the Sungei Buloh mangrove system in Singapore, using actual measured inflow concentrations and hydrodynamic modelling of tide in- and outflows. Delft3D was used to model the hydrodynamics and pollutants (as conservative substance) transport. The model was forced at its off...

MIST INTERNATIONAL JOURNAL OF SCIENCE AND TECHNOLOGY

Sundarbans, the largest mangrove forest located over the GBM basin, has impacted lives of million... more Sundarbans, the largest mangrove forest located over the GBM basin, has impacted lives of millions over the years. Standing against various natural disasters, rivers of Sundarbans have undergone major issues such as erosion-accretion of both the banks. The paper deals with a combination of remote sensing and Digital Shoreline Analysis System (DSAS), studying temporal behaviour of bank-lines along the main rivers of Sundarbans for the last three decades. The course of main rivers spanning from southwest Baleswar to west Bengal Bidyadhari within coverage of 10,000 sq. km. has been analyzed in this study. DSAS, the extension tool of ArcGIS, was used for monitoring the rate-of-change from multiple historic bank-line positions extracted from satellite images. Comparison of historic bank-lines between different rivers of Sundarbans was done based on Net Bank-line Movement (NBM) with an interval of five years. Finally, the results were presented graphically to get a better understanding of...

Journal of King Saud University - Engineering Sciences

International Journal of Engineering Sciences, Oct 1, 2019

The present study focuses on the entire coastline of Bangladesh, which was analyzed for the last ... more The present study focuses on the entire coastline of Bangladesh, which was analyzed for the last thirty years, with a five years' interval in between, to identify the changes in the shoreline position due to erosion or accretion. Shoreline positions for the time period 1989-2019, were manually digitized using multi-temporal Landsat satellite images of 30m resolution and comparable tidal conditions. A polygon-based approach was then employed in Arc GIS to determine the areal changes in the three different exposed coastal zones. The central zone was found to be the most dynamic in terms of both erosion and accretion. The western zone was mostly characterized by erosion, whereas only the eastern zone experienced a net land gain in this time span. Periodic reversal from erosion or accretion was also noted in several locations. The outcome of this study regarding the general trend (erosional or depositional) along the coastline, is expected to aid the proper planning and land management of the coastal zones in Bangladesh.

MATEC Web of Conferences, 2018

The projected increase in energy demand coupled with concerns regarding present reliance on fossi... more The projected increase in energy demand coupled with concerns regarding present reliance on fossil fuel and associated environmental concerns had led to increased interest in exploiting renewable energy sources. Among different renewable energy sources, tidal energy is unique and most suitable because of its predictable nature and capability to ensure supply security. Tide consists of both kinetic and potential energy which can be converted to electricity using well-proven technology. The potential energy of tides-the principal focus of the study, is stored due to rise and fall of the sea level. Head difference created due to tidal variation between basin side and sea side of a barrage stores potential energy which is converted into fast-moving water that rotates turbine and generates electricity. Bangladesh with its long coastline has promising prospects of tidal energy resource development. The study focuses on tidal energy resource exploration and exploitation along several competent locations of the Bengal coastline. Tidal records of flood and ebb tide of these locations are analyzed to calculate the potential energy. Finally, available potential techniques of energy extraction are evaluated for annually generated energy estimation. This study investigates the prospect and utilization of tidal energy concept and reviews the possibilities and opportunities of employment of the technology for sustainable development and climate change mitigation in context of Bangladesh.

With the rising concerns over global climate change associated with rapid depletion of limited fo... more With the rising concerns over global climate change associated with rapid depletion of limited fossil fuel resources, worldwide attention has intensified towards the potentials and possibilities of renewable energy sources. In the context of Bangladesh, among multifarious sources of renewables (solar, wind, biomass, tidal and wave power and ocean thermal energy) harnessing of energy from ocean tides, that cogitates both kinetic and potential energy, is a promising option. The former deals with tidal current energy conversion technologies while the latter concept focuses on the tidal barrage approach-similar to hydropower technique. This paper presents an assessment of the potential of tidal barrage technology through the development of a laboratory scale prototype model. The prototype energy extractor is constructed to study and verify the one-way generation method of tidal barrage technology. The model is scaled down to actual generation. A laboratory flume is used to generate a hydraulic head across a sluice gate, considering the upstream as basin side and downstream as the seaside. Water on the basin side is retained by the sluice, creating maximum head difference and thereby generates electricity while traversing through the turbine and rotating the generator. The generated power in the downstream end is measured by an ammeter. The amount of energy generated through the turbine is then compared to the theoretical energy generation. The findings of this study are discussed in relation to the prospects of tidal potential energy and identifies this technology as a preferable option for electricity generation in the suitable locations of the Bay of Bengal.

The International Journal of Ocean and Climate Systems, 2015

The Meghna Estuary is formed by the combined flows from three great rivers in the south-east Asia... more The Meghna Estuary is formed by the combined flows from three great rivers in the south-east Asia; the Ganges, the Brahmaputra and the Meghna. This estuary experiences dynamic hydro-morphological changes due to very high discharge of water and sediment from these three mighty rivers. Erosion and accretion occur simultaneously at very high rates; such that, the flow and sediment discharge through the estuary are the third highest and the highest, respectively, in the world. On the other hand, the tidal current itself is also strongly affected by the dynamic morphology changes. It is thus essential to understand the hydraulic behavior and interactive features of tides and morphology change in the estuary. With this end in view a two dimensional general model of Bay of Bengal was developed under cyclone shelter preparatory study (csps) undertaken by Bangladesh Government and the model was updated later during other projects. The present article focuses on development of model, its set-...

Climate, one of the major controlling factors for well-being of the inhabitants in the world, has... more Climate, one of the major controlling factors for well-being of the inhabitants in the world, has been changing in accordance with the natural forcing and manmade activities. Bangladesh, the most densely populated countries in the world is under threat due to climate change caused by excessive use or abuse of ecology and natural resources. This study checks the rainfall patterns and their associated changes in the north-eastern part of Bangladesh mainly Sylhet city through statistical analysis of daily rainfall data during the period of 1957 - 2006. It has been observed that a good correlation exists between the monthly mean and daily maximum rainfall. A linear regression analysis of the data is found to be significant for all the months. Some key statistical parameters like the mean values of Coefficient of Variability (CV), Relative Variability (RV) and Percentage Inter-annual Variability (PIV) have been studied and found to be at variance. Monthly, yearly and seasonal variation o...

PROCEEDINGS OF COASTAL ENGINEERING, JSCE, 2008

Ocean Modelling, 2015

Abstract The tidal variation in Singapore's coastal waters is influenced by large-scale, comp... more Abstract The tidal variation in Singapore's coastal waters is influenced by large-scale, complex tidal dynamics (by interaction of the Indian Ocean and the South China Sea) as well as monsoon-driven low frequency variations, requiring a model with large spatial coverage. Close to the shores, the complex topography, influenced by headlands and small islands, requires a high resolution model to simulate tidal dynamics. This can be achieved through direct nesting or multi-scale nesting, involving multiple model grids. In this paper, we investigate the effect of grid resolution and multi-scale nesting on the tidal dynamics in Singapore's coastal waters, by comparing model results with observations using different statistical techniques. The results reveal that the intermediate-scale model is generally sufficiently accurate (equal to or better than the most refined model), but also that the most refined model is only more accurate when nested in the intermediate scale model (requiring multi-scale nesting). This latter is the result of the complex tidal dynamics around Singapore, where the dominantly diurnal tidal currents are decoupled from the semi-diurnal water level variations. Furthermore, different techniques to quantify model accuracy (harmonic analysis, basic statistics and more complex statistics) are inconsistent in determining which model is more accurate.

International Journal of Engineering Sciences

Bangladesh is becoming increasingly vulnerable to the growing threat of climate change induced se... more Bangladesh is becoming increasingly vulnerable to the growing threat of climate change induced sea level rise. Considering the potential severe impacts that sea level rise will have on the coastal population and the country’s economy, it has become very important to know about the regional trends of changing sea levels along the coastlands of Bangladesh. The present study attempted to portray a representative scenario of sea level rise in the coastal regions of Bangladesh. Historic tide gauge records, ranging from 20 to 45 years, were used to determine reliable trends at multiple locations along the coast. Linear regression method was applied to derive the changing trend of annual high, mean and low tidal water levels. The location-specific trends of sea level rise determined in this study can be helpful to planners and policy makers to combat the emerging threat of SLR in a more efficient manner.

Journal of Urban and Environmental Engineering

Climate change can have profound impact on weather conditions around the world such as heavy rain... more Climate change can have profound impact on weather conditions around the world such as heavy rainfall, drought, global warming and so on. Understanding and predicting these natural variations is now a key research challenge for disaster-prone country like Bangladesh. This study focuses on the north eastern part of Bangladesh which is a hilly region, plays an important role in the ecological balance of the country along with socio-economic development. Present study analyses the behavior of maximum temperature and dry days using different statistical tools. Pearson’s correlation matrix and Man-Kendall’s tau are used to correlate monthly dry days with monthly maximum temperature, and also their annual trend. A moderate correlation was found mostly in dry summer months. In addition, a positive trend was observed in Man Kendall’s trend test of yearly temperature which might be an indication of global warming in this region.

The shallow waters of a nearshore region are dynamic and often hostile. Prediction in this region... more The shallow waters of a nearshore region are dynamic and often hostile. Prediction in this region is usually difficult probably by our limited understanding of the physics or by availability of accurate field data. It is a challenge for traditional in situ instruments to provide these inputs with the appropriate temporal or spatial density at a reasonable cost. Remote sensing provides an attractive alternative. An X-band nautical radar system was employed for this study to examine alongshore propagation of low frequency run-up motion around the research pier HORS in Hasaki beach, Japan. Analyses on radar echo images were done to estimate longshore distribution of shoreline positions and inter-tidal foreshore profile using time-averaged images. Spatio-temporal variation of water fronts were digitized manually from cross-shore time-stack images. Run-up heights were then estimated from the digitized water fronts with the help of foreshore slope. Run-up variations under dissipative cond...

Journal of Solid Waste Technology and Management

Journal of Urban and Environmental Engineering, 2014

The rainfall distribution in Bangladesh is not uniform and reflecting topography. Hilly Sylhet re... more The rainfall distribution in Bangladesh is not uniform and reflecting topography. Hilly Sylhet region receives substantial rainfall every year compare to other regions of Bangladesh. Though Sylhet region is less vulnerable to drought but weather pattern is not constant and changing day by day. Hence as a part of drought analysis, behavior of dry days is important. This study focuses on dry days pattern and associated changes from daily records of last 54 years for Sylhet region. Monthly, yearly and seasonal variations of dry days were analyzed to check for major changes. In order to investigate extreme dry events, time history of monthly dry days data were transformed into frequency domain using the Fast Fourier Transform (FFT). Variability of dry days in time scale was also checked from filtered signals which is very useful for drought analysis, agricultural development and disaster management for the north-east region of Bangladesh.

(In 4 Volumes, with CD-ROM), 2009

Electricity is the pinnacle of human civilization. At present, the growing concerns over signific... more Electricity is the pinnacle of human civilization. At present, the growing concerns over significant climate change have intensified the importance of use of renewable energy technologies for electricity generation. The interest is primarily due to better energy security, smaller environmental impact and providing a sustainable alternative compared to the conventional energy sources. Solar, wind, biomass, tide, and wave are some of the most reliable sources of renewable energy. Ocean approximately holds 2×10 TW of energy and has the largest renewable energy resource on the planet. Ocean energy has many forms namely, encompassing tides, ocean circulation, surface waves, salinity and thermal gradients etc. Ocean tide in particular, associates both potential and kinetic energy. The study is focused on the latter concept that deals with tidal current energy conversion technologies. Tidal streams or marine currents generate kinetic energy that can be extracted by marine current energy de...

World Academy of Science, Engineering and Technology, International Journal of Civil and Environmental Engineering, 2017

Electricity is the pinnacle of human civilization. At present, the growing concerns over signific... more Electricity is the pinnacle of human civilization. At present, the growing concerns over significant climate change have intensified the importance of use of renewable energy technologies for electricity generation. The interest is primarily due to better energy security, smaller environmental impact and providing a sustainable alternative compared to the conventional energy sources. Solar, wind, biomass, tidal, and wave power are some of the most reliable sources of renewable energy. Ocean approximately holds 2 × 103 tW of energy and has the largest renewable energy resource on the planet. Various forms constitute ocean energy namely, encompassing tides, ocean circulation, surface waves, salinity and thermal gradients. Ocean tide in particular, associates both potential and kinetic energy. The study is focused on the latter concept that deals with energy due to tidal current. Tidal currents generate kinetic energy that can be extracted by marine energy devices and converted into tr...

Mangroves are extremely important from the ecological and socio-economic perspectives, but are de... more Mangroves are extremely important from the ecological and socio-economic perspectives, but are degrading at an alarming rate nowadays. Besides direct clearance, hydrological alterations or climatic changes, chemical pollution could be a significant contributor of mangrove degradation. To understand chemical pollution in mangroves, the input and output (mass balance) of pollutants within a region need to be assessed. To identify critical situations that cause high concentrations of contaminants in the mangrove wetland, residence time was defined as the time required for flushing out pollutants from a determined region, and evaluated through numerical modeling. This concept was applied to a pollutant mass balance in the Sungei Buloh mangrove system in Singapore, using actual measured inflow concentrations and hydrodynamic modelling of tide in- and outflows. Delft3D was used to model the hydrodynamics and pollutants (as conservative substance) transport. The model was forced at its off...

MIST INTERNATIONAL JOURNAL OF SCIENCE AND TECHNOLOGY

Sundarbans, the largest mangrove forest located over the GBM basin, has impacted lives of million... more Sundarbans, the largest mangrove forest located over the GBM basin, has impacted lives of millions over the years. Standing against various natural disasters, rivers of Sundarbans have undergone major issues such as erosion-accretion of both the banks. The paper deals with a combination of remote sensing and Digital Shoreline Analysis System (DSAS), studying temporal behaviour of bank-lines along the main rivers of Sundarbans for the last three decades. The course of main rivers spanning from southwest Baleswar to west Bengal Bidyadhari within coverage of 10,000 sq. km. has been analyzed in this study. DSAS, the extension tool of ArcGIS, was used for monitoring the rate-of-change from multiple historic bank-line positions extracted from satellite images. Comparison of historic bank-lines between different rivers of Sundarbans was done based on Net Bank-line Movement (NBM) with an interval of five years. Finally, the results were presented graphically to get a better understanding of...

Journal of King Saud University - Engineering Sciences

International Journal of Engineering Sciences, Oct 1, 2019

The present study focuses on the entire coastline of Bangladesh, which was analyzed for the last ... more The present study focuses on the entire coastline of Bangladesh, which was analyzed for the last thirty years, with a five years' interval in between, to identify the changes in the shoreline position due to erosion or accretion. Shoreline positions for the time period 1989-2019, were manually digitized using multi-temporal Landsat satellite images of 30m resolution and comparable tidal conditions. A polygon-based approach was then employed in Arc GIS to determine the areal changes in the three different exposed coastal zones. The central zone was found to be the most dynamic in terms of both erosion and accretion. The western zone was mostly characterized by erosion, whereas only the eastern zone experienced a net land gain in this time span. Periodic reversal from erosion or accretion was also noted in several locations. The outcome of this study regarding the general trend (erosional or depositional) along the coastline, is expected to aid the proper planning and land management of the coastal zones in Bangladesh.

MATEC Web of Conferences, 2018

The projected increase in energy demand coupled with concerns regarding present reliance on fossi... more The projected increase in energy demand coupled with concerns regarding present reliance on fossil fuel and associated environmental concerns had led to increased interest in exploiting renewable energy sources. Among different renewable energy sources, tidal energy is unique and most suitable because of its predictable nature and capability to ensure supply security. Tide consists of both kinetic and potential energy which can be converted to electricity using well-proven technology. The potential energy of tides-the principal focus of the study, is stored due to rise and fall of the sea level. Head difference created due to tidal variation between basin side and sea side of a barrage stores potential energy which is converted into fast-moving water that rotates turbine and generates electricity. Bangladesh with its long coastline has promising prospects of tidal energy resource development. The study focuses on tidal energy resource exploration and exploitation along several competent locations of the Bengal coastline. Tidal records of flood and ebb tide of these locations are analyzed to calculate the potential energy. Finally, available potential techniques of energy extraction are evaluated for annually generated energy estimation. This study investigates the prospect and utilization of tidal energy concept and reviews the possibilities and opportunities of employment of the technology for sustainable development and climate change mitigation in context of Bangladesh.

With the rising concerns over global climate change associated with rapid depletion of limited fo... more With the rising concerns over global climate change associated with rapid depletion of limited fossil fuel resources, worldwide attention has intensified towards the potentials and possibilities of renewable energy sources. In the context of Bangladesh, among multifarious sources of renewables (solar, wind, biomass, tidal and wave power and ocean thermal energy) harnessing of energy from ocean tides, that cogitates both kinetic and potential energy, is a promising option. The former deals with tidal current energy conversion technologies while the latter concept focuses on the tidal barrage approach-similar to hydropower technique. This paper presents an assessment of the potential of tidal barrage technology through the development of a laboratory scale prototype model. The prototype energy extractor is constructed to study and verify the one-way generation method of tidal barrage technology. The model is scaled down to actual generation. A laboratory flume is used to generate a hydraulic head across a sluice gate, considering the upstream as basin side and downstream as the seaside. Water on the basin side is retained by the sluice, creating maximum head difference and thereby generates electricity while traversing through the turbine and rotating the generator. The generated power in the downstream end is measured by an ammeter. The amount of energy generated through the turbine is then compared to the theoretical energy generation. The findings of this study are discussed in relation to the prospects of tidal potential energy and identifies this technology as a preferable option for electricity generation in the suitable locations of the Bay of Bengal.

The International Journal of Ocean and Climate Systems, 2015

The Meghna Estuary is formed by the combined flows from three great rivers in the south-east Asia... more The Meghna Estuary is formed by the combined flows from three great rivers in the south-east Asia; the Ganges, the Brahmaputra and the Meghna. This estuary experiences dynamic hydro-morphological changes due to very high discharge of water and sediment from these three mighty rivers. Erosion and accretion occur simultaneously at very high rates; such that, the flow and sediment discharge through the estuary are the third highest and the highest, respectively, in the world. On the other hand, the tidal current itself is also strongly affected by the dynamic morphology changes. It is thus essential to understand the hydraulic behavior and interactive features of tides and morphology change in the estuary. With this end in view a two dimensional general model of Bay of Bengal was developed under cyclone shelter preparatory study (csps) undertaken by Bangladesh Government and the model was updated later during other projects. The present article focuses on development of model, its set-...

Climate, one of the major controlling factors for well-being of the inhabitants in the world, has... more Climate, one of the major controlling factors for well-being of the inhabitants in the world, has been changing in accordance with the natural forcing and manmade activities. Bangladesh, the most densely populated countries in the world is under threat due to climate change caused by excessive use or abuse of ecology and natural resources. This study checks the rainfall patterns and their associated changes in the north-eastern part of Bangladesh mainly Sylhet city through statistical analysis of daily rainfall data during the period of 1957 - 2006. It has been observed that a good correlation exists between the monthly mean and daily maximum rainfall. A linear regression analysis of the data is found to be significant for all the months. Some key statistical parameters like the mean values of Coefficient of Variability (CV), Relative Variability (RV) and Percentage Inter-annual Variability (PIV) have been studied and found to be at variance. Monthly, yearly and seasonal variation o...

PROCEEDINGS OF COASTAL ENGINEERING, JSCE, 2008

Ocean Modelling, 2015

Abstract The tidal variation in Singapore's coastal waters is influenced by large-scale, comp... more Abstract The tidal variation in Singapore's coastal waters is influenced by large-scale, complex tidal dynamics (by interaction of the Indian Ocean and the South China Sea) as well as monsoon-driven low frequency variations, requiring a model with large spatial coverage. Close to the shores, the complex topography, influenced by headlands and small islands, requires a high resolution model to simulate tidal dynamics. This can be achieved through direct nesting or multi-scale nesting, involving multiple model grids. In this paper, we investigate the effect of grid resolution and multi-scale nesting on the tidal dynamics in Singapore's coastal waters, by comparing model results with observations using different statistical techniques. The results reveal that the intermediate-scale model is generally sufficiently accurate (equal to or better than the most refined model), but also that the most refined model is only more accurate when nested in the intermediate scale model (requiring multi-scale nesting). This latter is the result of the complex tidal dynamics around Singapore, where the dominantly diurnal tidal currents are decoupled from the semi-diurnal water level variations. Furthermore, different techniques to quantify model accuracy (harmonic analysis, basic statistics and more complex statistics) are inconsistent in determining which model is more accurate.

International Journal of Engineering Sciences

Bangladesh is becoming increasingly vulnerable to the growing threat of climate change induced se... more Bangladesh is becoming increasingly vulnerable to the growing threat of climate change induced sea level rise. Considering the potential severe impacts that sea level rise will have on the coastal population and the country’s economy, it has become very important to know about the regional trends of changing sea levels along the coastlands of Bangladesh. The present study attempted to portray a representative scenario of sea level rise in the coastal regions of Bangladesh. Historic tide gauge records, ranging from 20 to 45 years, were used to determine reliable trends at multiple locations along the coast. Linear regression method was applied to derive the changing trend of annual high, mean and low tidal water levels. The location-specific trends of sea level rise determined in this study can be helpful to planners and policy makers to combat the emerging threat of SLR in a more efficient manner.

Journal of Urban and Environmental Engineering

Climate change can have profound impact on weather conditions around the world such as heavy rain... more Climate change can have profound impact on weather conditions around the world such as heavy rainfall, drought, global warming and so on. Understanding and predicting these natural variations is now a key research challenge for disaster-prone country like Bangladesh. This study focuses on the north eastern part of Bangladesh which is a hilly region, plays an important role in the ecological balance of the country along with socio-economic development. Present study analyses the behavior of maximum temperature and dry days using different statistical tools. Pearson’s correlation matrix and Man-Kendall’s tau are used to correlate monthly dry days with monthly maximum temperature, and also their annual trend. A moderate correlation was found mostly in dry summer months. In addition, a positive trend was observed in Man Kendall’s trend test of yearly temperature which might be an indication of global warming in this region.

The shallow waters of a nearshore region are dynamic and often hostile. Prediction in this region... more The shallow waters of a nearshore region are dynamic and often hostile. Prediction in this region is usually difficult probably by our limited understanding of the physics or by availability of accurate field data. It is a challenge for traditional in situ instruments to provide these inputs with the appropriate temporal or spatial density at a reasonable cost. Remote sensing provides an attractive alternative. An X-band nautical radar system was employed for this study to examine alongshore propagation of low frequency run-up motion around the research pier HORS in Hasaki beach, Japan. Analyses on radar echo images were done to estimate longshore distribution of shoreline positions and inter-tidal foreshore profile using time-averaged images. Spatio-temporal variation of water fronts were digitized manually from cross-shore time-stack images. Run-up heights were then estimated from the digitized water fronts with the help of foreshore slope. Run-up variations under dissipative cond...

Journal of Solid Waste Technology and Management

Journal of Urban and Environmental Engineering, 2014

The rainfall distribution in Bangladesh is not uniform and reflecting topography. Hilly Sylhet re... more The rainfall distribution in Bangladesh is not uniform and reflecting topography. Hilly Sylhet region receives substantial rainfall every year compare to other regions of Bangladesh. Though Sylhet region is less vulnerable to drought but weather pattern is not constant and changing day by day. Hence as a part of drought analysis, behavior of dry days is important. This study focuses on dry days pattern and associated changes from daily records of last 54 years for Sylhet region. Monthly, yearly and seasonal variations of dry days were analyzed to check for major changes. In order to investigate extreme dry events, time history of monthly dry days data were transformed into frequency domain using the Fast Fourier Transform (FFT). Variability of dry days in time scale was also checked from filtered signals which is very useful for drought analysis, agricultural development and disaster management for the north-east region of Bangladesh.

(In 4 Volumes, with CD-ROM), 2009