Spatial Disparity of Groundwater Depletion in Dhaka City (original) (raw)
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Groundwater Constrains and Opportunity: A key for Future Urban Planning of Dhaka City
Abstract Dhaka, the capital of Bangladesh is one of the densely populated cities in the world. The population of the city was rising rapidly since 1980s but the scope of urban expansion was not linear with its population increment. The estimation of water demand for 2025 was evaluated based on the existing population growth and required water demand. The study revealed that the total amount of groundwater abstraction in 2004 was 700 Mm3 that was 17 times higher than that of 1964. But during the last 40 years, the scenario change drastically due to employment opportunities, unplanned urbanization, population migration etc. In 2005, total number of deep tube wells was 435 that was one and half time higher than that of 2001. The lower Dupi Tila aquifer (third aquifer) ranges from surface to 353.28 m explored depth that lies within 35% of the sediment column while the Top aquifer (first) and Intermediate (second) Aquifer system lies within 32% of the sediment column. Water table in the shallow aquifer dropping rapidly in all over the city and the maximum declination of the groundwater level at present was found at -60.40 m at Tejgaon Industrial area. The average declining rate of water table in the Upper Dupi Tila aquifer is 2-2.5 m/year. This declining trend of groundwater level might be due to groundwater mining in the aquifer system; on the contrary, the deeper aquifer system has piezometric elevation of -10 m. From the long term aquifer test in the deeper aquifer system, the current study reveals that the average transmissivity of the system is 1805.61 m2/day, the storage coefficient is 0.00239 and the hydraulic conductivity is 27.09 m/day. Therefore, it is found that the deeper aquifer system might be only satisfy the future groundwater demand for the next 25 years with the high increasing trend of urbanization of Dhaka city.
PROCEEDING OF THE INTERNATIONAL SYMPOSIUM ON EFFICIENT GROUNDWATER RESOURCES MANAGEMENT, BANGKOK, THAILAND, PP 219-228. (2009)
Dhaka, one of the most densely populated cities in the world largely depends on groundwater to meet up the demand for its rapidly growing inhabitants. Groundwater is explored mainly from the fluvio-deltaic aquifer that provides 82% of total water supply that is about 2.0 million cubic meter (Mm 3 )/day. Shortage of water has already been experienced by the city dwellers. The volume extracts by private tubewells is more than the recorded abstraction. This uncontrolled development of groundwater has already created management problems in the city. Rapid urbanization without considering the hydro-geological aspects has brought significant changes in the geo-ecology. Decline of groundwater level, water logging, pollution, localized land subsidence etc. are the hazards associated with these changes. The rechargeable areas are being reduced due to urbanization and natural water recharge to aquifer cannot keep pace with the water withdrawal since three decades, causes alarming lowering of water level.
Abstract The study focused on the scope of sustainable water management and facing the challenges to accomplish the water demand for the next 25 years. The population of the city area is rapidly increasing due to centralization of all activities, migration of rural people due to the occurrence of disaster and creating employment opportunities for the last 40 years. Most of the supply-water in Dhaka city comes from groundwater and it covers 81% of the total supply. The water demand for the predicted population was analyzed up to 2025. The study obtained that groundwater table is dropping rapidly all over the city and recently the maximum lowering has been identified at Tejgaon industrial area. The groundwater elevation of shallow and intermediate aquifer at Tejgaon area has been calculated as – 62.4.m and – 13.14 m respectively. However, the average rate of water table declination is 2.5 meter/year. The over exploitation of this resource may occur land subsidence and moreover the concentration of trace elements are becoming higher in groundwater. Hereby considering all aspects, the study is innovated to apply some new and effective tools for the sustainable management of groundwater for the city dwellers. More attention may draw on the preservation of wetlands around the Dhaka city, artificial recharge of the shallow & intermediate aquifers from the peripheral channels, development of injection wells and rain water harvesting may play significant role for the fulfilment of water demand.
The Rate of Decline and Trend Line Analysis of Groundwater underneath Dhaka and Gazipur City
Journal of Water Resource and Protection
Groundwater is reported to account for 87% of all drinking water resources in Dhaka which has suffered a decline of up to 75 m in some specific location. Over-extraction of groundwater is an extensive social problem in Dhaka and Gazipur city which needs to be investigating thoroughly. This study presents the diagnosis of groundwater depletion pattern and the yearly rate of decline over the last three decades for Dhaka and Gazipur metropolitan area. Groundwater data were collected from the relevant institutions in order to analyse the trend line and the rate of decline of groundwater levels for more than 30 years period to understand the long-time variability. Ten individual stations datasets for GWL have been analyzed for Dhaka and Gazipur within a selected reference time period (1980-2012). The highest depleted GWL were found in the Mirpur station which is now 68 m below ground. To find out the time span when the depletion rate is highest, the rate of decline of all datasets has been computed which shows that 1998-2005 is the consecutive eight years time span with the fastest depletion rate. On the other hand, the annual trend-line analysis shows rapid depletion pattern after the year 2000.
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Dhaka city, having a population of about 18 million, depends heavily on groundwater as a source of quality water. However, the city is encountering a rapid depletion of groundwater, and its groundwater-based water supply is at risk of failure. This study was carried out to analyze the groundwater depletion scenarios occurring from 1970 to 2019 in the city and to find suitable options to sustain its water supply. The trends in groundwater levels (GWLs) were quantified by the non-parametric Sen’s slope and their significances were assessed by the modified Mann-Kendall test. Contour maps of GWL were generated to develop the contemporary GWL scenario in the city. Key informant interviews (KIIs) with the Dhaka Water Supply and Sewerage Authority (DWASA) officials, groundwater experts and researchers, in addition to semi-structured interviews with the DWASA consumers were conducted to assess current adaptation practices and to develop potential adaptation options. The effectiveness of the...
Groundwater Balance Study in the High Barind, Bangladesh
Rajshahi University Journal of Science, 2013
The annual groundwater recharge and discharge of aquifer of the Sapahar and Porsha Upazillas is estimated by Thiessen polygon method varies from 106.41 to 244 Mm3 and 93.77 to 291 Mm3 respectively. The calculated groundwater recharge of aquifer of the study area shows that the rate of groundwater recharge of aquifer in Porsha Upazilla is higher than that of Sapahar Upazilla and is characterized by very suitable groundwater storage potential. The overall groundwater balance study in the study area indicates that there exists a balance between annual recharge and withdrawal up to 1993 but after period of 1993 discharge exceeds the recharge continuing till today. But hereforth a cumulative annual deficit is found to exist because of progressive annual discharge in Sapahar Upazilla. 23.99 to 42.08 Mm3 of groundwater is discharged by discharging mechanisms. The rest of groundwater is discharged by natural seepage. DOI: http://dx.doi.org/10.3329/rujs.v39i0.16539 Rajshahi University J. of ...
Vulnerability of Dhaka Metropolitan Area Aquifer
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Bangladesh capital city, the metropolitan Dhaka is defendant on groundwater for domestic and industrial water supply. The demand of water for the city is increasing with time due to rapid increase in population and industry, but the rate of recharge to the aquifer is decreasing with increase in pavement area due to rapid urbanization. Due to this conflicting situation, the
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Dhaka city has emerged as the fastest-growing megacity, having more than 20 million inhabitants, with a growth rate of 3.62%. Unplanned and rapid urbanization, coupled with exponential population growth, has significantly altered the groundwater dynamics in Dhaka city. This study concentrates on the evolution of long-term piezometric heads of the Upper Dupi Tila aquifer (UDA) and the Middle Dupi Tila aquifer (MDA) based on long-term hydrographs, piezometric maps and synthetic graphical overviews of piezometric trends. Due to over-exploitation, the piezometric level (PL) has declined deeper than −85 and −65 m PWD (Public Works Department reference datum) in UDA and MDA, respectively. The highest rate of decline was observed in the south-central to southeastern parts of the city both in UDA (4.0 m/year) and MDA (5.74 m/year). The results clearly show that the rates of decline in PL vary from 2.25 to 5.74 m/year in both aquifers of the city, and urban expansion has greatly affected the...
International Conference on Sustainability in Natural and Built Environment (iCSNBE2019), 2019
Unsustainable depletion of groundwater from Madhupur tract aquifer (underneath Dhaka and Gazipur city) is an extensive social problem in the North central (N-C) part of Bangladesh. Specifically, Dhaka city, the capital of Bangladesh, suffers from over-extraction in an unsustainable manner. In addition to this phenomenon, natural disasters such as drought are amplified by climate change is a widespread natural hazard in Bangladesh. This study presents the characterization of drought using selected drought indicators developed using ground and global model data in Dhaka district in the North central part of Bangladesh and explores the mutual connection between drought years and the maximum groundwater level depletion years. Meteorological (precipitation, temperature) and groundwater data were collected from the relevant institutions in order to develop and analyze the drought indicators, climatic trends, and the rate of decline of groundwater levels. Where ground based data was lacking, global model datasets were downloaded from the EartH2Observe WCI portal to compute drought indicator based on appropriate global data. Analysis of drought occurrence shows that moderate to extreme drought occurred sixteen times in the last thirty-three years in the study area, showing that the frequency of severe drought is high. National historical drought impact records show that drought occurred twelve times, although these are not any specified records for Dhaka, as the focus of the impact data is agricultural impact. The effect of unsustainable overexploitation has been observed for the last two decades because of the extra abstraction of groundwater for the domestic water demand in the Dhaka districts. This was accelerated not only by the demographic explosion but also due the occurrence of droughts. This study also opens a new horizon of thinking that it is not necessary to use the drought monitoring system only for the agricultural sector. Monitoring of drought is necessary for all the sectors where problems of sustainability may exist. Dhaka has no drought monitoring that looks at the scale of impacts. Drought however does occur in the city, and indirectly works on a system and creates a negative feedback loop which leads to unsustainability.