Impact Assessment of Cloud Seeding in Karnataka, India

Abstract

The State of Karnataka in Southern India falls in the rain shadow region and is highly prone to drought conditions. Most of the monsoon rainfall occurs in the months of June and August with few rainy days during September to December. The State experienced severe rainfall deficiency in the years of 2017 and 2019 with limited rainfall in most parts of the State. The cloud seeding exercise was taken up by the State Government in both years to mitigate the adverse impact. Two cloud seeding aircrafts (Beach Aircraft King Air 200) of Weather Modification INC, USA with meteorological instruments and cloud seeding equipment were operated. Daily advisory on convective cloud development and potential seeding locations was generated using real time data from 3 Doppler Weather radars, Radio Sonde ascents, INSAT satellite data and high-resolution model runs by India Meteorological Department and Space Applications Centre (ISRO). Real time aircraft observations of cloud temperature, liquid water content and updraft winds helped to target potential clouds for hygroscopic and glaciogenic seeding. The data from the dense rainguage network of over 6000 automatic and telemetric rainguages operated by the Karnataka State Natural Disaster Monitoring Centre was utilized to study the impact of cloud seeding operations. Evaluation of the seeding has been carried out using spatial and statistical methods. The quantitative results indicate positive impact of cloud seeding leading to 10-15 % increase in rainfall
with improved geographical spread. Thus cloud seeding carried out in a controlled and systematic basis can thus emerge as a viable support to mitigate recurrent drought hit areas. This paper presents the results of the evaluation study.