Surface Air Temperature Distribution : A Study from Southwest Bangladesh

Surface air temperature distribution over the Ganges Delta Region of southwest Bangladesh and its tendency of warming are discussed through the analyses based upon the long-term temperature data from 1900-93. The data consist of two parts corresponding to the time-periods: 1973-93 and 1900-72. The study area is one of most affected places by the annual monsoon hydrological cycle and the present observation from these temperature data indicate that the surface air temperature gradient in the north-south direction is significant in the rainy season and that the temperature of the region is at an increasing tendency; the warming rate during the data periods (1900-93) on the long-term mean annual basis is estimated as 0.77℃ at Satkhira of the Khulna division and 0.29℃ as an areal average including the Barisal division, for the time difference of about half a century between the data periods before and after 1972

THE IMPORTANCE OF MONITORING TO ASSESS THE IMPACT OF CLIMATE CHANGE ON GROUNDWATER RESOURCES IN BANGLADESH

Groundwater is the major source of fresh water across much of the world, but there has been very little study on the impacts of climate change on this precious and finite resource. Rising levels of greenhouse gases are likely to increase the global average surface temperature over the next 100 years, raise sea levels and reduce soil moisture. The amount of water stored in the soil is fundamentally important to agriculture and influences the rate of actual evaporation, groundwater recharge and runoff. Rising sea levels would cause the tidal saltwater wedge to intrude further upstream in rivers, with resulting changes in salinity affecting coastal aquifers. Hence, to face the challenges of climate change-induced impacts in agriculture and water sectors, it is very important to assess the critical evidence of changes in the entire operational spectrum of the hydrologic cycle. Because of its geographic location and low-lying topographic condition, Bangladesh is likely to be in an extreme vulnerable situation; water resources in the low-lying coastal area are at maximum risk. In Bangladesh, a network for monitoring hydrological and hydrogeological data exists mainly to facilitate sustainable management of overall water resources of the country. The necessity is to upgrade, strengthen and expand monitoring technologies to track changes in the system due to climate change. This paper focuses on the development and design of monitoring network to monitor, identify and assess the obvious changes resulted from climate changes in coastal water resources

DETERMINATION OF SUSTAINABLE ZONES FOR GROUNDWATER ABSTRACTION FROM THE MULTI-LAYERED AQUIFER SYSTEM IN THE BENGAL BASIN, BANGLADESH

The use of deep groundwater (±300 m deep) is becoming an important issue in the Bengal Basin, due to both water quality problems and an acute shortage of available water in upper aquifers. In southeastern Bangladesh, multi-layered aquifer conditions exist with arsenic contamination at shallow depths, and high iron and brackish groundwater occurring mainly in the deeper layers. Many previous studies have offered explanations for the high concentrations of dissolved arsenic in groundwater - most of which proposed that the arsenic is derived from geo-genic sources and its release in groundwater is through natural processes, not the result of anthropogenic practices. About three million tube-wells, installed at shallow depths (10 to 50m), discharged groundwater with arsenic concentrations more than the Bangladesh drinking water standard of 50 µg/l. Toxic levels of arsenic typically occur in the middle Holocene sediments deposited in low-lying delta and floodplain areas, which adversely affects the health of millions of people. Aquifers are recharged by vertical percolation as well as water from a long distance traveling from highly elevated eastern hilly terrain to deeper aquifers. Arsenic or chloride-rich groundwater in the upper aquifers is not likely to be drawn into the deep aquifer under conditions of moderate use from the deep aquifer water. Under the current trend of groundwater abstraction, the possibility of a mass transport of arsenic in the lower part of the first aquifer, just below the arsenic-contaminated zone, will increase in future (?)

AN OVERVIEW OF SMARTWATER MANAGEMENT SYSTEM: STRATEGIC POTENTIAL IN BANGLADESH

Water loss management is becoming an increasingly important as supplies are stressed by population growth or water scarcity. A SmartWater system ensures optimum consumption and prediction of future water use. Bangladesh is one of the most vulnerable countries due to global climate change considering its rapid urbanization, inequitable land use, low income and greater reliance on climate sensitive sectors, particularly agriculture. Agricultural lands used for cropping and livestock rearing are more susceptible to degradation than non-agricultural lands. Most farmers irrigate through flooding, losing up to 75% of water to evaporation and creating a substantial drawdown of much needed water for the sustainability of seasonal crops. As a result, these traditional irrigation systems take four times the water they need to produce one ton of grain. In order to achieve a comprehensive SmartWater network solution, water systems require measurement and installation of sensing devices (Smart meters, sensors, and actuators), real-time communication channels, basic data management software, real-time data analysis and modeling software, and automation and control tools to conduct network management tasks remotely and automatically. Presently, the usable water quality and amount is constrained due to surficial contamination that takes places from various sources including anthropogenic reasons. Contemplation of any new or upgrading existing facilities for agricultural and urban needs, local Water Budget estimation should be taken into account and expanded to accommodate regional needs. To ensure an overall quality of water involving every sector, application of SmartWater Management warrants greater attention before initiating any new plan or upgrading facilities. Furthermore, an effective implementation of SmartWater concept should incorporate a comprehensive management structure at regional or city level, based on sustainability and self-reliance by adopting more intelligent solutions and technologies. It should also consider water recycling, water treatment technologies, and monitoring on regular bases

USING WATER QUALITY INDEX TO ASSESS GROUNDWATER SUITABILITY AT GAZIPUR DISTRICT, BANGLADESH

This study targeted to the suitability of groundwater for drinking purpose at Gazipur District undergoing rapid urbanization and increasing industrialization. The District has an area of 1741.53 km2, located in between 23°53\u27 and 24°21\u27 north latitudes and in between 90°09\u27 and 92°39\u27 east longitudes. From six Upazilas in Gazipur District, a total of 130 groundwater samples were collected, which are, Gazipur Sadar Upazila, Sreepur Upazila, Kaliakoir Upazila, Kapasia Upazila, and Kaligonj Upazila. A recent field observation review of industrial sludge found that heavy metal concentration was above the acceptable limit for agricultural soil. Gazipur being adjacent to Dhaka and has a similarly complex situation about contamination and abstraction. In recent years, the District has seen rapid growth in industrial development and increased urbanization. Water Quality Index (WQI), calculated per Horton’s method, used to assess groundwater condition and its vulnerability by taking into account thirteen parameters, namely, pH, TDS, sodium, potassium, calcium, magnesium, iron, manganese, bicarbonate, chloride, sulfate, nitrate, and fluoride. The computed WQI shows that comparatively collected water sample falls in excellent categories with few high points, probably due to localized industry and urbanization growth. WQI for the district has been classified using GIS into four categories, namely, Low, medium, high and very high. About 12 samples indicated high to very high WQI values. Spatial distribution analysis and Tree-map indicate a comparatively high concentration of WQI near the industrial areas within the District. Highest concentrations are evident at Gazipur Sadar Upazila, where urbanization and industrialization within the Gazipur District are highest and increasing at a rapid rate

Changing Behavior of Cyclone in Bangladesh and its Risk Assessment for Adaptation

Tropical cyclone (TC) is one of the most crucial topics not only for the natural loss but also for physical and economical loss of any country. The Bay of Bengal (BoB) generates number of tropical cyclones in each year. Bangladesh also experiences a number of cyclones. The surface temperature of the sea and air temperature is observed from NOAA high resolution satellite image. The Sea Surface Temperature (SST) of about 27°C and its higher is one of the prerequisite conditions for formation of a TC. But SST has increased by 1.2°C since last 40 years. It can be settled that both the Air Temperature and SST are increasing over the years. This rise in temperature of the BoB contributes to the occurrence of TC. Among the whole coastal zone of Bangladesh, the Chittagong- Cox’s Bazar coast and Barisal-Patuakhali coast are more vulnerable than the other parts. About 35 million people of Bangladesh are living in the TC exposed area. Most of the TC are associated with storm surges and heavy rainfall, which add up to the damages and complications in the risky area in addition to high winds. It also includes flash flood, salt water intrusion, and loss of lands. In case of vulnerability and risk, it is noticed that Bangladesh is hit by Severe TC (Category-5) at least one in every 10 years, where the wind speed crosses 220 Km/hr. The huge amount of rainfall and storm surge result in floods, which in- crease the severity of this hazard. By this time Government takes steps to reduce the damages of the coastal area. Also, the analysis of behavior of the track and damage of Severe TC indicates that the whole coastal zone stays at risk at different times of the year. With proper analysis and measures, the damages caused by TC can be reduced. The management system of TC risk is not sufficient. The study shows that the TC has significant impact of high winds, rainfall and storm surge. Accordingly, it has the impact on all relevant objects on the society in addition to human loss and damage. Though it has the main influence on the coastal areas but rainfall associated with TC has significant impact on all over Bangladesh. The impacts are dependent on the behavior, landfall time and landfall area. The impact has been divided into three classes- low, medium and high. The classified impacts are varying from TC to TC, but high impact is observed more times over southwestern part of Bangladesh. It also influences the vegetation of the coastal part. Proper measurements should be taken to reduce risk of vulnerable areas of TC in Banglades

ASSESSMENT OF THE IMPACTS OF URBANIZATION ON LAND-USE AND LAND-COVER CHANGES USING REMOTE SENSING AND PYTHON AT GAZIPUR DISTRICT, BANGLADESH

Urbanization has been the central demographic trend, not only in the Asia-Pacific region, but also for the entire world. Local geo-mapping is the vital tool for analyses of land-use and land-cover. This study attempts to classify land-use in unsupervised settings and create land-cover map by using open-source Landsat data integrated with GIS technologies and other ancillary resources. This work concentrates on Gazipur Sadar (an upazila or sub-district of the Gazipur District in central Bangladesh, part of the Dhaka Division) and Kaliakair, which are rapidly growing unplanned urban and industrial zones. The usage of python coding greatly assisted accomplishing the post-classification change detection analysis. Accurate assessment of urban growth and the spatiotemporal changes in land-use are becoming a routine practice for understanding urban dynamics and environmental impacts. Current research quantitatively examines the changes in land-use/land-cover and urban expansion in study areas. Gazipur is a growing metropolitan city north of the capital city of Dhaka in Bangladesh. The area experienced rapid industrialization followed by unplanned urbanization. In over two decades, Gazipur recorded an increase in urbanization (44.16%) with a decrease in forest areas (20.87%) and water bodies (5.88%). Meanwhile during the last five years, Gazipur had an accelerated change with an increase in urbanization (28.03%), a decrease of forest areas (26.29%) and water bodies (8.92%). This caused an environmental imbalance, a land-use pattern change, topsoil degradation, and habitat destruction. There has been a major change in vegetation pattern since 1991. The findings of this study and the geospatial information generated from the land-use mapping can be used as an important baseline reference for planners, policymakers, stakeholders, and other relevant interested groups in Bangladesh to contemplate multi-disciplinary planning and remediation measures to conserve finite land resources

STATISTICAL ANALYSIS OF GROUNDWATER LEVEL FLUCTUATION OF THE URBAN AND PERI-URBAN AREA OF GAZIPUR DISTRICT, BANGLADESH

Groundwater is the primary source for drinking, municipal, irrigation, and industrial water supply in Bangladesh. Due to unplanned urbanization and rapidly growing industries, the degradation situation has become perilous over time. Dhaka and its peri-urban regions are having drastic changes in groundwater (GW) levels. This work reviewed GW level fluctuation in the peri-urban area, which is now severely experiencing the detrimental impact of rapid urbanization and industrialization. Detail statistical investigation and Landsat image interpretation of the study area was conducted. Analysis and prediction of water level trends were conducted using variations of Mann Kendell tests. Gazipur Sadar (an upazila or sub-district of the Gazipur District in central Bangladesh, part of the Dhaka Division) is the most densely populated area of the Gazipur District, with a closely packed concentric build-up of industries within different urban settings. The alarming growth of industrialization and urbanization also affects water quality. Data analysis and interpretation indicated that the water level has been declining continuously since 2004, and the effect might reverberate throughout the next decade. Several wells showed a gradual decrease around 2004, but it accelerated almost exponentially within a decade. In 2004, the water level was around 5 meters below ground, but by 2013 it dropped down to 26 meters. To avoid further deterioration of the aquifer condition and combat the situation, an urgent action plan has become a dire necessity

TECTONIC AND GEOTECHNICAL REVIEW OF BENGAL BASIN FOR SEISMIC RISK ASSESSMENT IN BANGLADESH

Four major geotectonic provinces of the basin are recognized: 1) the continental slope to the west of the Hinge Zone, 2) the stable shelf, 3) the deep central trough (Sylhet-Hatiya) and 4) the Chittagong-Tripura fold belt to the east. The ~300 km long Dauki Fault demarcates the elevated Shillong Plateau, part of the Indian Shield to the north and the deep basin to the south. The basin experienced three strong to major intraplate earthquakes: a) 1885 Bengal earthquake (rev. Mw 6.8) close to the Hinge Zone, b) 1918 Srimangal earthquake (rev. Mw 7.1) on the Sylhet (trough) fault and c) 1923 Mymensingh earthquake (rev. Mw 7.0) at the northern end of the Hinge Zone where it intersects the Dauki Fault. In addition, Bangladesh also experienced similar tectonic energy release from the Shillong Plateau earthquakes like Great Assam Earthquake (1897, rev. Mw 8.1) and moderately active Indo-Burma subduction zone in the east. Rational assessment for seismic threats is determined by: hypocenter locations, the intensity of local/regional seismicity, differential tectonic stress condition, the geometry of discontinuities, and states of highest energy release. Site effects are evaluated from geophysical and geotechnical investigations. A 3D site-specific seismic hazard characterization of the capital megacity Dhaka is made to assess the seismic risk. It is observed that lateral and vertical discontinuities are subjected to multiple segmentations that facilitate tectonic movements. 1918 Srimangal event of Mw 7.1 is the largest recorded intraplate earthquake. Generation of enough tectonic stress in Bengal basin is very unlikely which might cause megathrust induced earthquakes (Mw 8-9) in Banglades