The vertical electrical soundings (VESs) are carried out in 24 selective locations of Chapai-Nawabganj area of northwest Bangladesh to determine the transmissivity and hydraulic conductivity of the aquifer. Initially, the transmissivity and hydraulic conductivity are determined from the pumping data of nearby available production wells. Afterwards, the T and K are correlated with geoelectrical resistance and the total resistivity of the aquifer. The present study deciphers the functional analogous relations of the geoelectrical resistance with the transmissivity and the total resistivity with the hydraulic conductivity of the aquifer in northwest Bangladesh. It has been shown that the given equations provide reasonable values of transmissivity and hydraulic conductivity where pumping test information is unavailable. It can be expected that the aquifer properties viz. transmissivity and hydraulic conductivity of geologically similar area can be determined with the help of the obtained equations by conducting VES experiments.

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Geoelectrical sounding, borehole litholog, and groundwater data have been used for the exploration of groundwater resources in the western part of greater Kushtia district, Bangladesh. This study aimed to delineate the boundary and the depth of aquifers, and assess their vulnerability to near-surface contaminants. Fourteen geoelectrical sounding data are interpreted and the corresponding geoelectrical logs are correlated with the available nearby horehole lithologs. Four distinct geoelectrical layers are identified within the depth of 105 m, namely thin topsoil (8.0-97.6 Ωm, 0.5-3.6 m), conductive clay-silt-sand layer (8.6-27.5 Ωm, 1.3-49.4 m), medium resistive fine grained aquifer (25.8-45.0 Ωm, 10.1-30.4 m), and high-resistive coarse grained water-bearing aquifer (35.0-64.9 Ωm, 30.0-76.9 m).The shallow aquifer (third layer) is found to occur at a depth ranging between 1.7 and 51 m, whereas the deeper aquifer (fourth layer) is found to occur within the depth between 14 and 52 m, both saturated with water. The groundwater resistivity and formation resistivity factor in the study area is found to vary from 15 to 30 Ωm and 1.93 to 2.68, respectively. The narrow low-protective layer has made the shallow aquifer highly vulnerable to surface contaminant in the study area.

Trace gases are important components for climate change process, and Earth's climate is sensitive to change in their atmospheric concentrations; therefore, proper assessment of trace gases is essential for ongoing global climate simulation. The spatio-temporal variations of four trace gases, namely carbon monoxide (CO), nitrogen dioxide (NO 2 ), ozone (O 3 ), and carbon dioxide (CO 2 ), over Bangladesh during the last decade are analysed using the remote-sensing data sets of the Atmospheric Infrared Sounder (AIRS) and Ozone Monitoring Instrument (OMI). Monthly, seasonal, and annual mean variations of trace gases were assessed. Higher CO, O 3 , and CO 2 concentrations show west-to-east gradient, indicating the impact of both local meteorology and emissions on variations in trace gases. On the other hand, total NO 2 concentration increases over Dhaka because of large population density, high traffic emission, larger industrial activities, and highly polluted air. The inter-annual variations of trace gases are mainly due to large-scale climatic phenomena such as El Niño and La Niña conditions. All the trace gases show strong seasonality, with higher levels during pre-monsoon season and lower levels during monsoon season, which are caused by the seasonal variations in biomass burning (BB), long-range transportation, and rainfall in South and Southeast Asia (S-SE Asia). However, O 3 concentration reveals minimum loading during winter season, associated with the reduction of O 3 formation in cold days due to insufficient heat. These findings are important to estimate regional climate variability due to trace gases.