Syamaprasad College

Rapid urbanization significantly influences the quantity and quality of natural water resources. This study investigates the impact of urban growth on the water quality of the Balason and Mahananda rivers in Siliguri. To evaluate the Water Quality Index (WQI), water samples for eleven physicochemical parameters were collected from seventeen selected sites. An upper - urban - downstream gradient approach was adopted, integrating statistical and GIS-based techniques for comprehensive analysis. WQI results indicated a marked decline in water quality during the lean season, particularly in densely populated urban stretches. Average WQI scores ranged from good to poor, with the most degraded sites located within the central urban zone. Statistical assessments revealed significant spatial variation in water quality across upstream, urban, and downstream segments. This research highlights that improving urban water quality aligns directly with SDG 6 (clean water and sanitation), suggesting the urgent need for integrated water resource management and sustainable urban planning.

UGA-SSMRPT2, the spin-free perturbative analogue of Mukerjee's State-Specific Multireference Coupled Cluster Theory (MkMRCC), is known to be successful for size-extensive and intruder-free construction of dissociation curves. This work demonstrates that UGA-SSMRPT2 is also an accurate and computationally inexpensive framework for computing the excitation energies. The method achieves near-chemical accuracy for the vast majority of π → π*, n → π*, charge-transfer, valence-Rydberg, and Rydberg excited states commonly used for benchmarking electronic structure theories for excited states. Our results demonstrate that UGA-SSMRPT2 excitation energies lie within 0.20 eV of EOM-CCSD and/or well-established theoretical best estimates, often surpassing the popular MRPT2 approaches like NEVPT2, CASPT2, and MCQDPT while typically requiring smaller active spaces. Its state-specific formulation circumvents the well-known intruder-state problem and eliminates the need for empirical parameters, such as IPEA shifts in CASPT2. This work proposes UGA-SSMRPT2 as a robust and scalable approach for modeling challenging electronically excited states.

Groundwater depletion and land subsidence have emerged as critical environmental challenges in rapidly urbanizing cities due to excessive groundwater extraction, increasing population pressure, and uncontrolled urban expansion. The present study investigates the relationship between groundwater depletion and potential land subsidence in the Kolkata Municipal Corporation (KMC), West Bengal, India, using geospatial techniques, Remote Sensing, Geographic Information System (GIS), and Analytical Hierarchy Process (AHP)-based Multi-Criteria Decision Analysis (MCDA). Groundwater fluctuation data for pre-monsoon and post-monsoon periods were collected from the Groundwater Year Book (GWYB) for the years 2010, 2013, and 2020. Various thematic layers, including aquifer depletion, geology, land use/land cover (LULC), urbanization growth, tectonic activity, and drainage pattern, were prepared and integrated to delineate groundwater potential and subsidence-prone zones. Inverse Distance Weighting (IDW) interpolation was applied to analyse spatial groundwater variability, while hydrochemical parameters were evaluated using the coefficient of variation (CV). The results reveal significant groundwater depletion in several parts of KMC, particularly within highly urbanized and densely populated zones. Urban expansion, reduced recharge potential, and unconsolidated geological formations were identified as major contributors to groundwater stress and potential land subsidence. The study highlights the effectiveness of integrating geospatial techniques and AHP-based MCDA for groundwater assessment and emphasizes the urgent need for sustainable groundwater management, artificial recharge measures, and continuous monitoring to reduce future subsidence risks in Kolkata.

In this article, we consider an extended evolutionary system involving fractional differential variational-like inequalities. The system consists of a nonlinear mixed variational-like inequality and an extended fractional differential equation in a complete normed linear space. We examine the non-emptiness, closedness, boundedness and convexity of solution set for the considered nonlinear mixed variational-like inequality in this setting. Furthermore, we establish upper semicontinuity and measurability of set valued solution map of the mixed quasi-variational inequality with respect to both state variable and time variable. Additionally, the existence of mild solutions for the system is shown by means of fractional operator theory, Bohnenblust-Karlin fixed point theorem for multivalued mappings and operator semigroup theory. We conclude by a numerical example, with the response times for different values of α.

In this work, a co-variational inequality problem and a co-resolvent equation problem are introduced and investigated. It is shown that the fixed point problem is equivalent to the problem of co-variational inequality. The co-variational inequality problem and the co-resolvent equation problem are equivalent due to this resemblance. The coresolvent equation problem is solved using an iterative approach that we provide at the final stage. Our findings may be seen as an enhancement of several established findings.