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 PO43 – 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.