Potential value of operationally available and spatially distributed ensemble soil water estimates for agriculture Konstantine P. Georgakakos * , Theresa M. Carpenter Hydrologic Research Center, 12780 High Bluff Drive, Suite 250, San Diego, CA 92130, USA Scripps Institution of Oceanography, UCSD, La Jolla, CA, USA Received 28 September 2004; received in revised form 10 December 2005; accepted 13 December 2005 Summary The focus of this paper is to develop a methodology to answer the question: do the spatially distributed soil water estimates produced by operational distributed hydrologic mod- els provide potential benefits for agriculture? The formulation quantifies the potential value through a cost–loss analysis, whereby cost for the farmer is associated with the decision to irri- gate the field and loss is associated with the decision not to irrigate while damaging soil water deficits occur. Farmer decisions are made in view of the likelihood of damaging events as esti- mated by the ensemble distributed model simulations of soil water deficit. The ensemble sim- ulations account for parametric and radar rainfall uncertainty. The application area for the economic value analysis is the farmland of the Illinois River watershed in northwestern Arkansas (mainly) and eastern Oklahoma, for which operational-quality distributed model input is avail- able. The land is used to produce hay for feed. The analysis indicates that there is substantial potential economic value in using the ensemble soil water estimates to make decisions regard- ing irrigation within the watershed for the months of July, August and September, when severe soil water deficits may occur. The benefits are higher for lower cost–loss ratios and for higher yield plants. They exhibit considerable spatial variability within the watershed in agreement with the spatial variability of the incidence of soil water deficits and with the spatial variability of the ability of the ensemble model simulations to reproduce this variability. The results of this study warrant additional analysis of the economic value of distributed model simulations in other regions, different distributed models and for other types of crops. Consideration of fore- casts in addition to simulations is also an important next step. Ó 2005 Elsevier B.V. All rights reserved. KEYWORDS Soil moisture; Distributed models; Irrigation; Ensemble simulation; Value of information 0022-1694/$ - see front matter Ó 2005 Elsevier B.V. All rights reserved. doi:10.1016/j.jhydrol.2005.12.018 * Corresponding author. Tel.: +1 858 794 2726; fax: +1 858 792 2519. E-mail address: KGeorgakakos@hrc-lab.org (K.P. Georgakakos). Journal of Hydrology (2006) 328, 177– 191 available at www.sciencedirect.com journal homepage: www.elsevier.com/locate/jhydrol