The Biobrio 12(3&4), 2025

Seasonal variation in physicochemical characteristics of Latratu Dam, Jharkhand, India

Ravi Rahul Singh, Madhumanti, Nupur Lal & Prasanjit Mukherjee

ABSTRACT:

Seasonal variability plays a central role in regulating the physico-chemical characteristics and ecological functioning of freshwater reservoirs in tropical regions. The present study investigates temporal variation in key water quality parameters of Latratu Dam, Ranchi district, Jharkhand, over a one-year period (April 2023-March 2024). Monthly sampling was conducted at six ecologically distinct stations to capture both seasonal trends and gradual intra-annual transitions. Parameters including water temperature, pH, dissolved oxygen (DO), biochemical oxygen demand (BOD), alkalinity, hardness, nitrate, and phosphate were analysed using standard methods. Water temperature followed a clear annual cycle, increasing from 18.2°C in winter to a peak of 31.5°C in June. Dissolved oxygen showed a progressive decline from 8.4 mg/L in winter to 5.1 mg/L in summer, indicating a substantial reduction in oxygen availability during warmer months. In contrast, BOD increased steadily from 2.4 mg/L in winter to 5.8 mg/ L in summer, reflecting intensified microbial activity. Nutrient concentrations exhibited a delayed seasonal response, rising gradually during pre-monsoon months and reaching peak values during monsoon (nitrate: 1.6 mg/L; phosphate: 1.1 mg/L), suggesting strong catchment-driven inputs. The combined monthly and seasonal patterns reveal a continuous cycle of warming, oxygen depletion, and nutrient enrichment followed by partial recovery. The period from late spring to early summer represents a phase of heightened ecological stress marked by elevated temperature, increased organic load, and reduced oxygen availability. Monsoon-driven nutrient influx indicates potential enrichment risk, while winter conditions support relative stabilization of the system. These findings highlight the importance of high-resolution temporal monitoring for understanding reservoir dynamics and guiding sustainable management strategies.

Keywords:    

Seasonal variation, limnology, water quality, freshwater reservoir, Latratu Dam

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