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MS Thesis - Daniel Whitesel

Impacts of Irrigation on a Precipitation Event During GRAINEX in the High Plains Aquifer Region

Date: Time: 1:30 pm–2:30 pm
Zoom Webinar
Contact: Rezaul Mahmood, rmahmood2@unl.edu
Land use land cover change, including irrigation, impacts weather and climate. In this thesis a precipitation event that occurred during the Great Plains Irrigation Experiment (GRAINEX) is investigated. The event was observed on the morning of 23 July 2018. Six model-based experiments were conducted which involved increase or decrease of soil moisture by 5% and up to 15% over the irrigated croplands. These changes were approximation of soil moisture content in response to different levels of irrigation applications. An additional experiment, where irrigated land use was changed to grassland, was conducted to capture pre-irrigation land use and its impacts. It was found that regardless of level of irrigation, average precipitation decreased. However, precipitation decrease was greater under drier conditions. In addition, as observed, the model did not produce precipitation over non-irrigated land use. When grassland replaced the irrigated agriculture, increases in precipitation was reported. With increased irrigation, latent heat flux increased compared to control simulation and decreased when irrigation decreased. On the other hand, sensible heat flux was decreased compared to control when irrigation increased. The planetary boundary layer over irrigated land use was shallower than over non-irrigated land use while over grassland it was higher than irrigated but lower than non-irrigated land use. The changes in precipitation, the surface energy balance, and the planetary boundary layer served as a reminder of irrigation’s complex effects on the atmosphere. Additional analysis of the other precipitation events during GRAINEX would be helpful to better understand the effects of irrigation.

https://unl.zoom.us/j/98764897856

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This event originated in School of Natural Resources.