Modelling the Effect of Land Use and Land Cover Changes on Groundwater Recharge

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Groundwater is the world's largest available freshwater resource. More than half of the world’s population depends on this resource for domestic supply. A global assessment on groundwater resources indicates a constant decline in water storage among principal aquifers. Aquifer recharge is complex, influenced by climate conditions; land use and land cover (LULC) dynamics; aquifer lithology, and topography. Climate and LULC have significant effect on the recharge process due to their direct impact on soil infiltration. Urbanisation-induced LULC changes lead to the rise in impervious surface coverage, causing a decrease in infiltration and a significant decline in groundwater recharge rates. However, due to the complex nature of groundwater recharge and lack of databases, studies on the effects of LULC and climate on the groundwater recharge is minimal. Therefore, this study is aimed at the effects of LULC and climate on the groundwater recharge process for a coastal urban shallow aquifer of Cochin, Kerala, India. The study was accomplished in two parts, with the first part based on direct observations from the study area aided by satellite datasets and secondary datasets. The second part is on forecasting future scenarios, based on modelling. A series of LANDSAT satellite data sets were used to analyse the historical LULC dynamics of Cochin from 1994 to 2020. The analysis indicates that the rapid urbanisation and other anthropogenic activities have adversely affected all major natural land cover classes for the past three decades. To understand the changes in groundwater potential zones due to the changing LULC, a multi-criteria decision analysis (MCDA) approach was adopted in a GIS platform. Historical groundwater potential index maps (GWPI) were derived using six geo-environmental factors by keeping all other factors static with changing LULC. Change detection analysis was performed on the historical GWPI to derive groundwater potential change index (GWPCI). The study reveals the impact of the LULC dynamics on groundwater potential.
Supervisor: Nair, Archana M
Groundwater, Climate Change, Land use Land Cover, Coastal Aquifer, Modelling