Impacts of irrigation on land-atmosphere interactions in high-resolution model simulations
| Author(s) | Lawston, Patricia M. | |
| Date Accessioned | 2017-04-18T11:26:43Z | |
| Date Available | 2017-04-18T11:26:43Z | |
| Publication Date | 2017 | |
| Abstract | In the United States, irrigation represents the largest consumptive use of freshwater and accounts for approximately one-third of total water usage. Irrigation impacts soil moisture and can ultimately influence clouds and precipitation through land–planetary boundary layer (PBL) coupling processes. This dissertation is a collection of three studies that analyze the impact of irrigation on the atmosphere using NASA modeling tools the Land Information System (LIS) and the NASA Unified Weather Research and Forecasting Model (NU-WRF) framework. ☐ The first study investigates the effects of drip, flood, and sprinkler irrigation methods on land–atmosphere interactions, including land–PBL coupling and feedbacks at the local scale. The offline and coupled simulation results show that regional irrigation impacts are sensitive to time, space, and method and that irrigation cools and moistens the surface over and downwind of irrigated areas, ultimately resulting in both positive and negative feedbacks on the PBL depending on the time of day and background climate conditions. ☐ The second study assesses the sprinkler irrigation scheme physics and model sensitivity to choice of irrigation intensity and greenness fraction over a small, high resolution domain in Nebraska and evaluates the model performance with Cosmic Ray Neutron Probe (CRNP) observations. Results show that differences between experiments are small at the interannual scale, but become more apparent at seasonal and daily time scales. In addition, field-scale heterogeneity resulting from the individual actions of farmers is not captured by the model and the amount of irrigation applied by the model exceeds that applied at the two irrigated fields. However, the seasonal timing of irrigation and soil moisture contrasts between irrigated and nonirrigated areas are simulated well by the model. ☐ The third study assesses the individual and combined impacts of irrigation and wind turbines on surface fluxes, near surface temperature, and humidity. Results show that irrigation repartitions surface sensible and latent heat fluxes, reduces daytime temperatures and increases temperatures at night. Turbines weaken surface sensible heat fluxes minimally during the day but enough at nighttime to slightly reduce near surface temperature. The simulations that include both turbines and irrigation show that wind power production is slightly reduced when irrigation is included and irrigation contributes to a greater reduction in daytime surface sensible heat fluxes than would be realized with only turbines. Taken together, these three studies showcase the dramatic alterations that irrigation induces to the water and energy cycles and demonstrates the potential for human impacts on weather and climate. | en_US |
| Advisor | Hanson, Brian | |
| Degree | Ph.D. | |
| Department | University of Delaware, Department of Geology | |
| Unique Identifier | 982656556 | |
| URL | http://udspace.udel.edu/handle/19716/21229 | |
| Publisher | University of Delaware | en_US |
| URI | https://search.proquest.com/docview/1884697352?accountid=10457 | |
| dc.subject.lcsh | Irrigation. | |
| dc.subject.lcsh | Wind turbines. | |
| dc.subject.lcsh | Cosmic ray neutrons. | |
| Title | Impacts of irrigation on land-atmosphere interactions in high-resolution model simulations | en_US |
| Type | Thesis | en_US |