Modeling the atmospheric response to irrigation in the great plains. Part I: General impacts on precipitation and the energy budget

Keith J. Harding, Peter K. Snyder

Research output: Contribution to journalArticlepeer-review

69 Scopus citations

Abstract

Since World War II, the expansion of irrigation throughout the Great Plains has resulted in a significant decline in the water table of the Ogallala Aquifer, threatening its long-term sustainability. The addition of near-surface water for irrigation has previously been shown to impact the surface energy and water budgets by modifying the partitioning of latent and sensible heating. A strong increase in latent heating drives nearsurface cooling and an increase in humidity, which has opposing impacts on convective precipitation. In this study, the Weather Research and Forecasting Model (WRF) was modified to simulate the effects of irrigation on precipitation. Using a satellite-derived fractional irrigation dataset, grid cells were divided into irrigated and nonirrigated segments and the near-surface soil layer within irrigated segments was held at saturation. Nine April-October periods (three drought, three normal, and three pluvial) were simulated over the Great Plains. Averaging over all simulations, May-September precipitation increased by 4.97 mm (0.91%), with localized increases of up to 20%. The largest precipitation increases occurred during pluvial years (6.14 mm; 0.98%) and the smallest increases occurred during drought years (2.85 mm; 0.63%). Precipitation increased by 7.86 mm (1.61%) over irrigated areas from the enhancement of elevated nocturnal convection. Significant precipitation increases occurred over irrigated areas during normal and pluvial years, with decreases during drought years. This suggests that a soil moisture threshold likely exists whereby irrigation suppresses convection over irrigated areas when soil moisture is extremely low and enhances convection when antecedent soil moisture is relatively high.

Original languageEnglish (US)
Pages (from-to)1667-1686
Number of pages20
JournalJournal of Hydrometeorology
Volume13
Issue number6
DOIs
StatePublished - Dec 1 2012

Keywords

  • Atmosphere-land interaction
  • Biosphere-atmosphere interaction
  • CAPE
  • Convective-scale processes
  • Hydrometeorology
  • Moisture/moisture budget

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