Hydrologic and other issues related to operational cloud seeding programs

Fundamentally, the potential benefit of rainfall enhancement from operational cloud seeding in semi-arid regions is increased water volume and quality for a number of uses including rainfed and irrigated agriculture, human consumption and industry. Recent field experiments designed to verify increased precipitation rates and volume from cloud seeding are promising, but thorough hydrologic and socio-economic impact analysis should be undertaken if operational programs are to be developed. Crucial questions exist, such as whether rainfall augmentation, in the long-run, is a viable and cost-effective option to deliver additional runoff water and increased water yield, and if so, what is the operational scale necessary and at what cost to achieve increased benefits? The benefits of the rainfall augmentation could be a decrease in soil moisture deficits for rainfed agriculture and increased storage of runoff water in reservoir systems to meet irrigation, municipal and industrial water demands. Along with these benefits are potential costs, including those directly related to the operational cloud seeding program and indirectly, such as environmental impacts like soil erosion, sedimentation and landscape changes; and potential, unforeseen social costs. To understand these benefits and costs, comprehensive studies should be conducted that address both physical and social issues surrounding rainfall augmentation programs.