Excessive withdrawal of Groundwater for Urban Demand of Dhaka City: Emergency Measures needs to be Implemented to Protect the Aquifer (original) (raw)
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Spatial Disparity of Groundwater Depletion in Dhaka City
[Groundwater is of course a valuable natural resource for the people of Dhaka City as surface water such as lake, river, reservoir etc. are not accessible to them sufficiently. People of Dhaka City depend on groundwater specially to meet their urgent daily needs. But the present conditions of groundwater in the city are not favorable for its population. In many parts of the city there is scarcity of pure water. This study shows that the groundwater in Dhaka city is declining at an alarming rate. The continuous over withdrawal of ground water and irregular and insufficient recharge causes depletion of groundwater. Rapid growing urbanization in the past 30 years also contributed to the present condition of Dhaka City. Recently, it is found out that the declining trend of groundwater in Dhaka City is 3 meters per year. Moreover, predictions show that the demand is increasing day by day and no chances of improving the situation is there. The volume of groundwater in storage is decreasing in many areas of the Dhaka City due to permanent over pumping. Thus, it has become obligatory to find out solutions for improvement. Therefore, scientific research on groundwater depletion in Dhaka City is very crucial to bring out fruitful solutions.]
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.
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.
Vulnerability of Dhaka Metropolitan Area Aquifer
2000
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
The inexorable expansion of the world's urban population and the realisation that water resources are finite have forced many developing cities in emergent economies to consider how sustainability can be introduced into their plans for infrastructural improvement. Groundwater-dependent cities should feel this need keenest. Yet the pace of urban aquifer management remains slow. Simple but contextsensitive aquifer protection policies would help plan for sustainable urban development, especially if stakeholder involvement increases the chances for the gap between policy enactment and enforcement/compliance to be closed. The experience of two such developing cities in Bangladesh and Kyrghyzstan that are attempting to develop their own groundwater protection plan along sound hydrogeological principles is described.
Response of the Dupi Tila aquifer to intensive pumping in Dhaka, Bangladesh
Hydrogeology Journal, 2003
This paper focuses on the water-quantity issues facing Dhaka because of the rapid exploitation of the Dupi Tila aquifer. Dhaka is one of the world's largest groundwater-dependent cities, relying on water withdrawn from this underlying semiconfined sand aquifer. A meteoric rise in well construction in both the private and public sectors in recent years has produced an estimated 1,300 boreholes that tap the aquifer in urban and suburban parts of the city. Analysis of construction records for public-supply wells drilled between 1970 and 2000 shows that water levels are falling in several areas of the city despite apparently favorable recharge conditions. The productivity of boreholes as measured by specific capacity has also declined significantly. Even though the aquifer system is vital to the infrastructure of the city it remains a poorly quantified resource, and until this is resolved by investment in evaluation studies, attempts to efficiently manage the resource in a sustainable way will be frustrated. mediante la inversión en estudios de evaluación, los intentos por gestionar eficientemente los recursos de forma sustentable serµn infructuosos.
Sustainability
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...
Water
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...
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.