Award Date

12-15-2025

Degree Type

Thesis

Degree Name

Master of Science (MS)

Department

Geoscience

First Committee Member

Hannes Bauser

Second Committee Member

Carrie Tyler

Third Committee Member

Markus Berli

Fourth Committee Member

Nicole Pietrasiak

Number of Pages

62

Abstract

Biological soil crusts (biocrusts) are miniature ecosystems of living organisms incorporated within the soil matrix and established in the topmost millimeters of the soil surface. Biocrust plays a critical role in the hydrologic processes in arid lands, yet the extent to which it increases or decreases evaporation remains unclear. To gain a better understanding of the impact of biocrust on evaporation compared to bare soil, I studied a cyanobacteria-dominated biocrust patch surrounded by bare soil atop a lysimeter in the Mojave Desert near Las Vegas, Nevada. Using high-resolution thermal imaging, and the known latent heat flux from the lysimeter, I monitored spatial and temporal patterns in surface temperature and applied the three-temperatures (3T) model to estimate spatially resolved biocrust evaporation. This approach allows us to: 1) determine the heterogeneous evaporation patterns due to the presence or absence of biocrust, and 2) evaluate changes of these evaporation patterns over time, particularly after rain events. The surface temperature of biocrust was consistently lower than surrounding bare soil, which suggests a higher latent heat flux. The 3T model captured evaporation fluxes at a pixel scale, revealed the spatial variability in soil surface evaporation, and confirmed a higher evaporation rate of the biocrust compared to the average evaporation of the lysimeter after a rain event. This study highlights that small-scale heterogeneity in soil surface cover, specifically patches of cyanobacteria-dominated biocrust, influences evaporation in arid lands. Understanding how biocrust influences evaporation advances our understanding of the hydrologic cycle of arid environments. This study offers valuable insights into cyanobacterial biocrust evaporation and contributes to a better understanding and prediction of the water balance in arid lands.

Keywords

Arid Land Hydrology; Biocrust; Biocrust Evaporation; Lysimeter; Thermal Imaging; Three Temperatures Model

Disciplines

Civil and Environmental Engineering | Geotechnical Engineering | Hydrology

File Format

PDF

File Size

2600 KB

Degree Grantor

University of Nevada, Las Vegas

Language

English

Rights

IN COPYRIGHT. For more information about this rights statement, please visit http://rightsstatements.org/vocab/InC/1.0/

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