Impacts of Large-Scale Groundwater Exploitation Based on Long-Term Evolution of Hydraulic Heads in Dhaka City, Bangladesh

Abstract

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 shape and extent of the depression cone over the past four decades. The magnitudes of the depression cones in both aquifers seem to pose a considerable threat to groundwater resources, indicating that the current exploitation is not sustainable at all.

A Novel Hybrid Model for Developing Groundwater Potentiality Model Using High Resolution Digital Elevation Model (DEM) Derived Factors

“…In flood susceptibility mapping, the multicollinearity test is a crucial step. Multicollinearity refers to the presence of a linear relationship between several or all of a regression model's independent parameters [84]. A division-by-zero in regression calculation might be caused by the existence of a linear connection between variables.…”

“…The study region's inventory graph includes 50 well points collected from various resources and detailed site inspection. First, non-groundwater data similar to the groundwater data utilized for GWP modeling must be prepared [84]. The selection was made on the basis of the field survey, with equivalent numbers of non-groundwater data (50 points).…”

Untitled

“…Due to intensive withdrawals in megacities, the dramatic lowering in groundwater levels persisted for ages (Islam et al, 2021;Kagabu, et al, 2011;Onodera, 2011). Dhaka is one such city characterised by a significant cone of depression with water table elevations of -49 to -69 m during 1980-2018, where groundwater abstraction now exceeds recharge.…”

Spatial and Temporal Distribution of Groundwater in Open-Pit Coal Mining: A Case Study from Baorixile Coal Mine, Hailaer Basin, China

“…Open-pit coal mining groundwater drainage can cause groundwater disturbance [9,[11][12][13][14], and the existing articles on groundwater in open-pit mines mainly focus on the prediction of groundwater inflow [2,[14][15][16][17], groundwater as a disaster-causing factor for the safety evaluation of open-pit mine slopes [18][19][20][21][22], groundwater chemistry [5,6,23], and ecological evaluation [3,4,23,24]. There are many articles on the change and prediction of groundwater inflow caused by open-pit mining from the perspective of numerical simulation, such as Soni and Manwatkar [16] used the modflow model to simulate and predict the groundwater inflow and groundwater flow field changes in an open-pit coal mine in India under different mining conditions.…”