Deltin 7

The Deltin 7 Aviator গেম টাকা ইনকাম of Deltin 7 has its own water supply system and entirely relies on groundwater. Ten groundwater samples were collected from 10 production wells of 120-320 m depth across the Deltin 7 Aviator গেম টাকা ইনকাম campus from upper and lower Dupi Tila aquifers. The pH values revealed that water is mildly acidic to neutral and electrical conductivity (EC) values ranging from 325 to 654 μS/cm, indicating fresh groundwater. The total hardness (TH) of the samples ranges from 76-203 mg/L, suggesting moderately hard to very hard water. Of the ten groundwater samples, nine are of Ca-Mg-HCO3 type, whereas one shows Ca-Na-HCO3 type of groundwater. The saturation indices show that the groundwater samples are near-saturated for calcite, dolomite, gypsum, siderite, and rhodochrosite, indicating the low potential for dissolution-precipitation of these mineral. Notably, the results of WQI indicate that all the wells are safe for drinking. As of July 2023, the groundwater level was 72 m below ground level with a declination rate of 2.8 m/year. The estimated hydraulic conductivity values of 20 to 90 m/day and transmissivity values of 637 to 2740 m²/day suggest better permeability and water transmission potential within the lower aquifer. These results provide essential information for the university authority to implement appropriate strategies for efficient groundwater management.

The people living in the Kaptai-Lichubagan roadcut area of Kaptai Upazila in Rangamati Hill District, Bangladesh, rely on groundwater for drinking. This study aims to investigate the hydrochemistry of groundwater and river water, associated hydrochemical processes and to assess drinking water quality. In total, 26 water samples were collected for laboratory analysis; 22 from groundwater at depths ranging from 9 to 198 meters, and 4 from Karnaphuli river. Both groundwater and river water pH levels suggest acidic to neutral water. Electrical conductivity (EC) values also indicate mostly fresh groundwater and river water, and EC of groundwater varies both spatially and vertically.  The total hardness (TH) of groundwater suggests moderately hard to very hard water, whereas the river water is mostly soft. Most groundwater samples are either Ca-Mg-HCO3 type or mixed Ca-Na-HCO3 and Ca-Mg-SO4-Cl type. In contrast, all the river water samples are Ca-Mg-HCO3 type. Groundwater exhibit variable polygonal shapes in stiff diagrams, characterized by relatively low to moderate major ions. However, there is one sample which shows higher cations suggesting anthropogenic influence. River water show similar patterns but smatter shapes characterized by relatively low major ions. Groundwater is primarily influenced by water-rock interaction andsilicate weathering is the dominant controlling factor of groundwater chemistry, followed by carbonate dissolution. Groundwater samples are mostly undersaturated with minerals - calcite, dolomite, gypsum, and siderite, which possess the potential for dissolution. None samples exceed the Bangladesh drinking standard (BDS) for As (50 µg/L). River water is also As safe.  While As shows no spatial variability, FeTotal shows significant spatial variability in the study area. Water Quality Index (WQI) indicates about 90% water samples including most groundwater and all river water samples is of excellent quality for consumption Routine monitoring of the water quality in this area is recommended to ensure its continued safety.

Riverbank migration is a common phenomenon in the floodplains of Bangladesh. The continuous changes in river morphology affect its surrounding land-use patterns which pose threats to the life and property of people living near the rivers. The present study utilized thirty-one (1989-2020) years of satellite data to track the erosion-accretion and its influence on land-use and land-cover (LULC) change of Hizla Upazila using GIS-based Modified Normalized Difference Water Index (MNDWI) and Google Earth Engine (GEE) respectively. Statistical analysis revealed the average erosion rate (5.03 km2) is lower than accretion (5.72 km2), resulting in a net land gain of 24.93 Km2. The spatial distribution of erosional activity suggests that the central and western parts of Hizla Upazila are mostly affected, compared to the eastern part, where new deltas are forming. This phenomenon is attributed to the westward movement of the Lower Meghna River (LMR), making the central and western parts of Hizla more vulnerable. The pattern of land-use change manifests that nearby settlements and vegetation are primarily at risk due to channel migration. A significant decrease in total water area (2.1%) and an increase in bare land area (5.1%) between 1997-2010 indicates substantial deposition. Concurrently, there was a decrease in the total settlement (1.53 km2) and vegetation area (9.8 Km2), indicating natural hazards like floods and high-intensity rainfall. The overall kappa accuracy for LULC is over 85% demonstrating its suitability for forecasting. The outcomes of this study will aid the local community, policymakers, and researchers in mitigating risk and ensuring sustainability.

Managed  (MAR) has been applied as Aquifer Storage, Transfer, and Recovery (ASTR) to provide fresh  for local communities at 99 locations in southwest Bangladesh since 2009. Aerobic freshwater from ponds is filtered and subsequently infiltrated into anaerobic shallow brackish aquifers. At approximately 45% of these sites, relatively higher levels of Fe and As were observed in recovered water, which requires a better understanding of the hydrogeochemical processes that govern the Fe, Mn, and As levels in these MAR systems. Therefore, two representative sites with As above (74 ± 11 μg/L at site GMF11) and below (19 ± 6 μg/L at site JJS91), the Bangladesh drinking water standard of 50 μg/L were weekly monitored on hydrochemical changes from Dec 2017 to Dec 2018. Hydrogeochemical processes occurring during storage were quantified with inverse and forward geochemical mass balance models developed with PHREEQC. The following processes explained the changes in water quality: 1) mixing of infiltration water with native groundwater (∼90%:∼10%); 2) consumption of O2 by a) dissolved Fe2+ that subsequently precipitated as Fe(OH)3 at GMF11 and by b) dissolved and sedimentary organic matter (OM) at site JJS91; 3) reduction of SO4 coupled to the oxidation of OM at both sites; and 4) mixing corrosion and freshening induced cation-exchange (Ca ; Na desorption) triggering  and  dissolution at GMF11. Dissolution of these occurred to a lesser extent at JJS91, while cation exchange (Na sorption; Ca desorption) suggested that the freshwater was displaced by brackish groundwater because of inadequate infiltration at JJS91. Distinct pH values in recovered water reflected the dominance of Fe2+ versus OM oxidation. Siderite dissolution led to 4.3 ± 3.1 and 1.0 ± 0.5 mg/L Fe in recovered water at GMF11 and JJS91, respectively. Elevated As and Mn levels in recovered water were caused for max. 20% by mixing with native groundwater and for min. 80% by mobilization processes, mainly by desorption of As from Fe-oxides and by the dissolution of Mn-bearing siderite. Recommendations are provided to improve recovered water quality.