Economic Feasibility of Riparian Irrigation with Weather Uncertainty

Abstract

Some farmers may have the opportunity to irrigate using riparian water sources, that is, adjacent surface water bodies such as rivers and streams. The purpose of this study is to evaluate the profitability of irrigating crops from riparian sources when the yield response to irrigation is random. A computerized crop simulation model is used to predict the yield response of corn (Zea mays L.) to irrigation under variable weather conditions. The crop model is calibrated using data from field experiments. The study is carried out for the Pamunkey River Basin of eastern Virginia on a Pamunkey fine sandy loam (fine-loamy, mixed, thermic Ultic Hapludalfs). Twenty-three years of weather data are used to represent random weather variability. The profitability of the investment is determined using the net present value (NPV) approach. The results indicate that water can be profitably pumped over 1 mi on a low water-holding capacity soil. The distance that water can profitably be pumped is sensitive to the water-holding capacity of the soil. Results also show returns from riparian irrigation to be very sensitive to the yield response to irrigation and output prices. The results imply that there is potential for expanded irrigation from riparian sources. If such expansion occurs, the increased demands on streamflows may lead to periodic water shortages and conflicts.