Impacts of a massive flood event on the physico-chemistry and water quality of river Pampa in Western Ghats of India

ABSTRACT

Kerala state (India) experienced a devastating flood event during the month of August 2018 which has brought considerable changes to the environment and ecosystem, especially to rivers. One of the worst affected basin was Pampa river which experienced a severe flood. Aims of this investigation were to define the quality of Pampa river water after the flood. The analysis of physico-chemical parameters indicated transitory variations from pre-flood status as reported by former workers. The pre-flood neutral to the acidic property of water shifted towards alkaline conditions throughout the river stretch post flood. Alkalinity and salinity was almost twice the pre-flood scenario, though the values were within the ranges required for fish survival and growth. Decreased conductivity and increased dissolved oxygen were also the major changes observed post flood. The study indicates that this large-scale flood resulted in a considerable reduction in the concentration of heavy metals and nutrients in the water. Based on water quality index, spatially Pampa river water can be categorised from ‘Good’ to ‘Unsuitable’ category. The cluster analysis distinctly differentiates the middle stream stations from lower stream stations. PCA/FA loadings indicate that electrical conductivity, alkalinity, total hardness, calcium, and PO₄^{3 –} P show strong positive loadings which indicate that salinity factor and natural weathering are the main factors controlling the water quality. This information would be practical to forecast the health of the ecosystem after the flood and also to develop adequate management plans.

KEYWORDS:

• Extreme flood
• water quality
• water quality index
• multivariate analysis
• Pampa river

Acknowledgments

We acknowledge the support and help received from Kerala State Fisheries Department, Govt. of Kerala, India. Our deepest gratitude is to the fishers who selflessly helped in collecting water samples and sharing the information and materials on pre-flood and post-flood scenarios without which it would have not been possible to complete the study. Authors are grateful to the Director, ICAR-Central Inland Fisheries Research Institute, Barrackpore, Kolkata, India, for financial support and laboratory facilities to carry out the research work.

Authors’ contributions

Ajoy Saha: Corresponding author, conceptualization, sample collection & analysis, data analysis, manuscript preparation. Sibina Mol S: Contribute during research design, sample collection and analysis. Deepa Sudheesan: Interpret data, manuscript review, and editing. Vettath Raghavan Suresh: Coordination of the work. Subir Kumar Nag: Heavy metal analysis and interpretation. Preetha Panikkar: Manuscript review and editing. Basanta Kumar Das: Provided overall guidance.

Disclosure statement

The authors declare that they have no conflict of interest.

Data availability statement

The datasets generated and analysed during the present investigation are not publicly available and upon request, data can be available from the corresponding author on reasonable request.

Supplementary material

Supplemental data for this article can be accessed here.

Additional information

Funding

This work has been funded by ICAR-Central Inland Fisheries Research Institute, Barrackpore from its institutional research grant.