An Evaluation Of The San Joaquin Operational Cloud Seeding Program Using Monte Carlo Permutation Statistics

Abstract

An independent target-control statistical evaluation of the Southern California Edison (SCE) Upper San Joaquin River Basin Weather Modification Program, also known as the Big Creek Cloud Seeding Project, was conducted using Monte Carlo permutation statistics. The cumulative effect of seeding over the entire history of the project through water year 2006 was calculated in terms of confidence intervals because they provide information on the strength of the seeding effect and, thereby, allows informed judgments to be made about its cost-effectiveness and societal value. The effect of seeding on several targets in the Upper San Joaquin River Basin was evaluated using the control(s) that gives the most precise evaluation results possible with the available data. Evidence for positive, statistically significant and cost-effective increases in streamflow after 56 years of seeding was found for Mono Creek and Pitman Creek, but the results for Bear Creek were not statistically significant. Physical studies that help explain the statistical results and that could lead to more cost-effective seeding operations are suggested.