• Anil M Pophare

Articles written in Journal of Earth System Science

• Evaluation of coal bed methane potential of coal seams of Sawang Colliery, Jharkhand, India

The coal seams of Sawang Colliery, East Bokaro Coalfields are bituminous to sub-bituminous in nature and categorized as high gaseous seams (degree II to degree III level). These seams have the potential for coal bed methane (CBM) and their maturity increases with increasing depth, as a result of enhanced pressure-temperature conditions in the underground. The vitrinite maceral group composition of the investigated coal seams ranges from 62.50-83.15%, whereas the inertinite content varies from 14.93-36.81%. The liptinite content varies from 0.66% to 3.09%. The maximum micro-pores are confined within the vitrinite group of macerals. The coal seams exhibit vitrinite reflectance values (Ro% calculated) from 0.94% (sample CG-97) to 1.21% (sample CG-119).

Proximate analyses of the investigated coal samples reveal that the moisture content (M%) ranges from 1.28% to 2.98%, whereas, volatile matter (VM%) content is placed in the range of 27.01% to 33.86%. The ash content (A%) ranges from 10.92% to 30.01%. Fixed carbon (FC%) content varies from 41.53% to 55.93%. Fuel ratio variation shows a restricted range from 1.53 to 1.97. All the coal samples were found to be strongly caking and forming coke buttons.

The present study is based on the adsorption isotherm experiments carried out under controlled P-T conditions for determination of actual gas adsorption capacity of the coal seams. This analysis shows that the maximum methane gas adsorbed in the coal sample CG-81 is 17m3/t (Std. daf), at maximum pressure of 5.92MPa and experimental temperature of 30°C. The calculated Langmuir regression parameters $P_L$ and $V_L$ range from 2.49 to 3.75MPa and 22.94 to 26.88m3/t (Std. daf), respectively.

• Morphometric analysis of Suketi river basin, Himachal Himalaya, India

Suketi river basin is located in the Mandi district of Himachal Pradesh, India. It encompasses a central inter-montane valley and surrounding mountainous terrain in the Lower Himachal Himalaya. Morphometric analysis of the Suketi river basin was carried out to study its drainage characteristics and overall groundwater resource potential. The entire Suketi river basin has been divided into five sub-basins based on the catchment areas of Suketi trunk stream and its major tributaries. Quantitative assessment of each sub-basin was carried out for its linear, areal, and relief aspects. The analysis reveals that the drainage network of the entire Suketi river basin constitutes a 7th order basin. Out of five sub-basins, Kansa khad sub-basin (KKSB), Gangli khad sub-basin (GKSB) and Ratti khad sub-basin (RKSB) are 5th order subbasins. The Dadour khad sub-basin (DKSB) is 6th order sub-basin, while Suketi trunk stream sub-basin (STSSB) is a 7th order sub-basin. The entire drainage basin area reflects late youth to early mature stage of development of the fluvial geomorphic cycle, which is dominated by rain and snow fed lower order streams. It has low stream frequency (Fs) and moderate drainage density (Dd) of 2.69 km/km2. Bifurcation ratios (Rb) of various stream orders indicate that streams up to 3rd order are surging through highly dissected mountainous terrain, which facilitates high overland flow and less recharge into the subsurface resulting in low groundwater potential in the zones of 1st, 2nd, and 3rd order streams of the Suketi river basin. The circulatory ratio (Rc) of 0.65 and elongation ratio (Re) of 0.80 show elongated nature of the Suketi river basin, while infiltration number (If) of 10.66 indicates dominance of relief features and low groundwater potential in the high altitude mountainous terrain. The asymmetry factor (Af) of Suketi river basin indicates that the palaeo-tectonic tilting, at drainage basin scale, was towards the downstream right side of the drainage basin. The slope map of Suketi river basin has been classified into three main zones, which delineate the runoff zone in the mountains, recharge zone in the transition zone between mountains and valley plane, and discharge zone in the plane areas of Balh valley.

• Impact of over-exploitation on groundwater quality: A case study from WR-2Watershed, India

The WR-2 watershed is located in the Deccan trap basaltic terrain of Maharashtra State, India. The watershed area incorporates a rich orange orchard belt that requires a huge quantity of water for irrigation. This requirement is mostly met through groundwater, extracted from the shallow aquifers of the WR-2 watershed. However, over the years, excess withdrawal of groundwater from these aquifers has resulted in depletion of groundwater level. The declining trends of groundwater level, both long term and short term, have had a negative impact on the groundwater quality of the study area. This effect can be gauged through the rising electrical conductivity (EC) of groundwater in the shallow aquifers (dug wells) of the WR-2 watershed. It is observed that the long term declining trend of groundwater level, during 1977–2010, varied from 0.03 to 0.04 m per year, whereas the corresponding trend of rising EC varied from 1.90 to 2.94 𝜇S/cm per year. During 2007–2010, about 56% dug wells showed a positive correlation between depleting groundwater level and rising EC values. The groundwater level depletion during this period ranged from 0.03 to 0.67 m per year, whereas the corresponding trend of rising EC ranged from 0.52 to 46.91 𝜇S/cm per year. Moreover, the water quality studies reveal that groundwater from more than 50% of the dug wells of the WR-2 watershed is not suitable for drinking purpose. The groundwater, though mostly suitable for irrigation purpose, is corrosive and saturated with respect to mineral equilibrium and shows a tendency towards chemical scale formation.

• # Journal of Earth System Science

Volume 131, 2022
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