COVID-19 is a pandemic disease caused by severe acute respiratory syndrome corona virus 2 (SARS-CoV-2). The study area, Tamilnadu, is a southern state in India. The present study demonstrates the significance of mapping in identifying the risk zones of COVID-19 disease by taking a study of COVID-19 cases in Tamilnadu state. The main objective of the study was to identify the risk zone of COVID-19 disease in the first wave of Tamilnadu through geospatial mapping. Data on COVID-19 cases collected during March 2020 to March 2021 month wise in all 37 districts (unit area) of Tamilnadu in two-month interval wise was analysed. The study is based on secondary sources from respective office in Tamilnadu. Z-score techniques were used for standardizing data. Correlation analysis provided a measure of correlation between COVID-19 and working population. Location Quotient analysis aided the identification of COVID-19 risk zones in Tamilnadu. Present study indicates tertiary workers are more vulnerable to COVID-19 disease.

The water resource on earth surface is circulated and attains different forms; of which runoff is a major component. The runoff in any area depends on the amount of precipitation, terrain, soil type and characteristic, slope, land use activity in that region and many other location specific factors. There are several methodologies adopted world wide to estimate the runoff; one important and widely used techniques is the NRCS-CN method. This method uses precipitation, soil group and land use as the major input factors. The present study is carried out in a watershed, named the Vannathangarai watershed, a part of Noyyal river basin, which is a tributary of River Cauvery, a major river draining through southern India. The study reveals that runoff is positively correlated with precipitation and is very high in areas with slope