Impact of Eastern Redcedar Encroachment on Water Resources in the Nebraska Sandhills

Authors

Yaser Kishawi, University of Nebraska-LincolnFollow
Aaron R. Mittelstet, University of Nebraska-LincolnFollow
Troy E. Gilmore, University of Nebraska-LincolnFollow
Dirac Twidwell, University of Nebraska-LincolnFollow
Tirthankar Roy, University of Nebraska-LincolnFollow
Nawaraj Shrestha, University of Nebraska-Lincoln

Document Type

Article

Date of this Version

2023

Citation

Science of the Total Environment 858 (2023): 159696

doi: 10.1016/j.scitotenv.2022.159696

Comments

Copyright © 2022, Elsevier. Used by permission

Abstract

Worldwide, tree or shrub dominated woodlands have encroached into herbaceous dominated grasslands. While very few studies have evaluated the impact of Eastern Redcedar (redcedar) encroachment on the water budget, none have analyzed the impact on water quality. In this study, we evaluated the impact of redcedar encroachment on the water budget in the Nebraska Sand Hills and how the decreased streamflow would increase nitrate and atrazine concentrations in the Platte River. We calibrated a Soil and Water Assessment Tool (SWAT model) for streamflow, recharge, and evapotranspiration. Using a moving window with a dilate morphological filter, encroachment scenarios of 11.9%, 16.1%, 28.0%, 40.6%, 57.5%, 72.5% and 100% were developed and simulated by the calibrated model. At 11.9% and 100% encroachment, streamflow was reduced by 4.6% and 45.5%, respectively in the Upper Middle Loup River, a tributary to the Platte River. Percolation and deep aquifer recharge increased by 27% and 26% at 100% encroachment. Streamflow in the Platte River, a major water source for Omaha and Lincoln, would decrease by 2.6%, 5.5% and 10.5% for 28%, 57.5%, and 100% encroachment of the Loup River watershed, respectively. This reduction in streamflow could increase nitrate and atrazine concentrations in the Platte River by 4 to 15% and 4 to 30%, respectively. While the density of redcedar is minimal, it is important to manage their encroachment to prevent reductions in streamflow and potential increases in pollutant concentrations.

Includes supplemental material