Assessment of Physico-Chemical Parameters of Water at Selected Stations of Krishna River, Kolhapur District

INTRODUCTION

Water is a vital natural resource and a fundamental requirement for the survival of living organisms. It has been instrumental in the evolution and maintenance of life on Earth. Water is extensively used for domestic consumption, agricultural irrigation, and industrial activities. Rivers and streams constitute important components of the natural environment and support human populations, aquatic life, wildlife, and vegetation (Hasse and Blodgett, 2009).

Rivers play a crucial role in sustaining life by providing water for drinking, irrigation, fisheries, and industrial purposes. There is major seven rivers in India, the Brahmaputra, Indus Tapi, Godavari, Mahanadi, Krishna and Narmada, along with their numerous tributaries (Balasubramanian, 2013). The Krishna River is among the longest rivers of India with length is about 1400 km (Sutar et al., 2025). It originates near Mahabaleshwar in the Western Ghats and flows through Maharashtra, Karnataka, Telangana, and Andhra Pradesh before draining into the Bay of Bengal. In Maharashtra, the river flows through Kolhapur, Sangli and Satara districts and is extensively used by the local population (Comprehensive study report on Krishna River stretch, 2014).

Water quality represents the ability of water bodies to support biological life and meet human needs. Maintaining good water quality is necessary to ensure safe drinking water, recreational use, and the protection of aquatic ecosystems. Water pollution occurs when human activities cause changes in the physical, chemical, or biological properties of water, rendering it unsuitable for its intended uses (Jyoti, 2021).

In recent years, increasing population pressure, agricultural practices, discharge of municipal sewage, and industrial effluents have deteriorated river water quality (Singh et al., 2004). Physico-chemical analysis is a fundamental tool for evaluating the health of aquatic ecosystems and determining the suitability of water for various purposes. Several studies have emphasized the need for continuous monitoring of the Krishna River to prevent further degradation.

MATERIALS AND METHODS

Study Area

Kolhapur district lies between 15°43′ to 17°17′ N latitude and 73°40′ to 74°42′ E longitude. The Krishna River flows through the eastern part of the district, receiving water from tributaries such as Panchganga, Dudhganga and Warna. The region experiences a tropical monsoon climate with heavy rainfall during June to September and influences river water quality. After intensive survey 5 sampling stations (Kanwad, Ghalwad, Hasur, Nrusinhawadi, and Bubnal) were selected at approximate distance. Water samples were collected monthly from selected locations along the river.

Sample Collection

Water samples were collected from five selected sampling stations over a period of one year, from February 2023 to January 2024. Standard procedures recommended in limnological literature were followed for the analysis of physico-chemical characteristics of water (APHA-2017, Workbook on Limnology by Adoni et al., and Chemical and Biological methods for water pollution studies by Trivedy and Goel). Parameters such as water temperature, pH, transparency, Dissolved Oxygen (DO), and free CO₂, were measured directly at the sampling sites. Laboratory analyses were carried out to determine total hardness, Electrical Conductivity (EC), Turbidity, Total solids, Total dissolved solids, Total suspended solids, alkalinity, chloride, nitrate, and phosphate. At each sampling station, water samples were collected in clean 1-litre polythene bottles. Necessary precautions were taken during sampling, handling, and transportation to avoid contamination.

Laboratory Analysis

The collected water samples were examined in the laboratory to assess their physico-chemical properties. All glassware used during the analysis was pre-treated with dilute nitric acid and rinsed with distilled water to prevent possible contamination. Details of parameters, their units, and methodology with their brief description is given in Table 1.

RESULTS

Monthly variations in the physico-chemical characteristics of surface water from the selected stations were evaluated to understand the hydrological status of all the stations (Tables 2 3 4 5 6).

Temperature

is a primary factor controlling chemical reactions and biological processes in aquatic systems. During the study period, water temperature varied between 20 and 26ºC. Similar range have been noted by various workers. Khan et al. (2017) have reported range between 19 to 26ºC of the Narmada River, El Morhit et al. (2014) observed temperature variation between 19.2 to 29.2ºC of the Loukkos River, Islam et al. (2015) recorded 22 to 30ºC of the Karnaphuli River, Sahoor et al. (2016) documented range 22 to 28ºC. Highest temperature was noted during April 2023 of Ghalwad station and lowest was noted during October 2023 of Bubnal, Nrusinhawadi and Kanwad stations and January 2024 of Bubnal. pH The pH values ranged from 6.2 to 8.9, indicating slightly acidic to moderately alkaline conditions. Highest pH was noted during May 2023 at Hasur and lowest during December 2023 at Bubnal station. Many workers found maximum pH in summer and minimum in winter Bera et al. (2023), Snyder et al. (2021), Zhang et al. (2025).

Electrical Conductivity

varied from 116 to 672 µS/cm, reflecting changes in dissolved ionic content. Highest conductivity was recorded during December 2023 at Nrusinhawadi and lowest during July 2023 at the same station.

Transparency

showed pronounced seasonal variability, ranging from 20.3 to 99.06 cm. Maximum was observed at Hasur during April 2023 and Minimum was observed during July 2023 at Kanwad station.

TDS (Total Dissolved Solids)

TDS ranges from 0.08 mg/L to 0.368 mg/L. Highest TDS was noted during January 2024 at Nrusinhawadi while lower were noted during May 2023 at Ghalwad.

Total Hardness

values ranged from 60 to 302 mg/L, classifying the water as soft to hard. Maximum value of hardness was noted during February 2023 at Kanwad and minimum was noted December 2023 at Hasur station.

Alkalinity

values ranged from 22 to 102 mg/L, indicating moderate buffering capacity of the river. Maximum alkalinity was noted during February 2023 at Nrusinhawadi and minimum was during August 2023 at Bubnal.

Chlorides

Chloride concentrations varied from 25.52 to 68.06 mg/L, Highest concentration of chlorides was observed during January 2024 at Bubnal and Ghalwad stations where as lowest was recorded during September 2023 of Bubnal.

Nutrients (Nitrate and Phosphate)

Nitrate concentrations ranged from 0.348 to 2.597 mg/L while phosphate values varied between 0.0223 and 0.2334 mg/L. Higher nutrient levels during summer may be linked to increased microbial activity and internal nutrient recycling, whereas lower concentrations during the monsoon are attributed to dilution. Although nutrient levels were generally low, occasional increases in phosphate may enhance the risk of eutrophication under favourable conditions.

Free Carbon Dioxide

concentrations ranged between 4.4 and 35.2 mg/L and did not exhibit a consistent seasonal pattern.

Fluctuations in CO₂ levels may be influenced by respiration, decomposition of organic matter, and photosynthetic uptake.

Occasional higher concentrations could indicate increased biological activity or organic load in water.

Dissolved Oxygen

values ranged from 2.4 to 7.2 mg/L. Maximum value was noted during August 2023 at Nrusinhawadi, July 2023 at Hasur, Kanwad and Ghalwad whereas minimum value was recorded during Feb’23 of Hasur.

DISCUSSION

Table 3: Physico-chemical Singh et al. (2018). The decline in water temperature during winter can be attributed to reduced ambient temperatures, which may further be influenced by increased wind velocity and higher water levels. In contrast, the elevated water temperature observed during the summer season is mainly due to increased ambient temperature resulting from high intensity of light and reduced water levels (Patil, 2014).

Higher pH values observed during summer may be associated with enhanced photosynthetic activity, leading to reduced carbon dioxide levels in water. Lower pH during winter could be linked to organic matter decomposition and increased respiration (APHA, 2017). Overall, pH values remained within acceptable limits, suggesting favourable conditions for aquatic life.

Higher value of electrical conductivity in winter might result from evaporation and concentration of dissolved salts, while lower values during the monsoon are attributed to dilution by rainwater. Seasonal fluctuations in conductivity indicate the influence of hydrological processes on ionic composition.

Higher transparency during Summer indicates effective settling of suspended particles, while reduced transparency during the monsoon reflects increased turbidity caused by surface runoff carrying silt and organic matter from the catchment area. Such seasonal variation in transparency directly influences light penetration and primary productivity. TDS is important as it reflects salinity, these dissolved mineral content in water affects water quality used for drinking, agriculture, aquatic life, and ecosystem health.

Lower hardness during the monsoon season may be due to dilution effects, whereas higher values during winter are likely caused by leaching of calcium and magnesium salts from surrounding soils and rocks. Seasonal variation in hardness reflects the influence of catchment geology and hydrological conditions.

Higher alkalinity during winter may be related to reduced biological utilization of bicarbonates, while lower values during monsoon due to dilution of river water by heavy rainfall which reduces concentration of carbonates and bicarbonates.

Elevated levels of chloride during winter may be due to evaporation and agricultural practices, whereas reduced concentrations during the monsoon are likely the result of dilution. Chloride levels remained within permissible limits, suggesting minimal pollution impact.

Higher concentrations of Dissolved oxygen during monsoon may be attributed to lower water temperature and increased physical aeration of water due to heavy rainfall which increases oxygen solubility, while reduced levels during summer are associated with elevated temperature and increased biological oxygen demand. Overall DO levels indicate good aeration and favourable ecological conditions.

CONCLUSION

The physico-chemical assessment of the Krishna River at selected stations in Kolhapur district revealed that all parameters were within the permissible limits prescribed by the World Health Organization (WHO). However, elevated free CO₂ concentrations at certain stations reflect localized anthropogenic influences, primarily due to increased carbon load from domestic wastewater discharge and surface runoff.

To sustain the existing water quality, regular monitoring should be continued, with particular attention to carbon-related parameters. Effective treatment of wastewater, control of runoff, and strict enforcement of environmental regulations are recommended to minimize anthropogenic impacts and ensure long-term ecological sustainability of the Krishna River.