Anthropogenic Impacts on the Hydrochemical and Geochemical Characteristics of the Vellayani Tropical Freshwater Lake of Kerala, India

The formation of lakes takes place due to various natural mechanisms on the Earth's surface including tectonic activities, erosional processes, and some volcanic causes. The lakes influence the local weather conditions of the region and have a supreme impact on the lives of the people living in and around it. Lakes have become popular recreational destinations in many regions of the world, as well as an essential element of the tourist sector, generating money and providing a source of income for locals. Lake Vellayani is a natural tropical freshwater lake located on the west coast of God’s own country Kerala, South India. This lake’s water serves as an important perennial drinking water supply as well as irrigation water for the inhabitants of Kalliyoor, Venganoor, and Vizhinjam gram panchayats. The anthropogenic interventions evidently show the decline of the lake area from 750 ha in 1926 to 222 ha by 2019. Furthermore, the point and nonpoint sources of contamination of the lake have continuously been questioned from a public health standpoint. 9 surface water samples and 7 sediment samples were collected to investigate the hydrogeochemistry of Lake Vellayani by computing the water quality index (WQI), contamination factor (CF) and degree of contamination, and chemical index of alteration (CIA). The results of the water quality index reveal that most of the surface water in the Vellayani Lake meets the requirements for drinking as well as irrigation purposes. This chapter has provided basic baseline data on the hydrochemical and geochemical features of Lake Vellayani, as well as insight into the pace of contamination and the need for conservation.