Hydrology Commons^™

Transboundary Groundwater Flow Between Niger And Nigeria In The Iullemeden Aquifer System, Gare Ambrose-Igho

UNLV Theses, Dissertations, Professional Papers, and Capstones

Groundwater is important in regions where water resources are not abundantly distributed such as arid and semi-arid regions. In many countries in Africa, groundwater serves as the most reliable source of water supply and supports over 50% of the African population. Groundwater is stored in underground water-bearing permeable rocks, rock fractures, or unconsolidated materials known as aquifers. Groundwater can be transboundary, meaning it crosses international political boundaries between two or more sovereign states. Transboundary aquifers are prone to overexploitation that depletes the groundwater resource and can cause a lowering of the water table and possible ground subsidence. Overexploitation in transboundary …

Harnessing Backcasting To Identify Drivers Of Critical Warming At Hoover Dam Using Hydrodynamic And Machine Learning Models, Eunice Ledres

UNLV Theses, Dissertations, Professional Papers, and Capstones

Elevated water temperatures can pose a significant threat to dam infrastructure, potentially damaging turbines, overheating internal components, and forcing generator shutdowns. This study uses a backcasting framework to evaluate how future scenarios may result in elevated water temperatures. Backcasting defines undesirable outcomes and works backward to identify the conditions that lead to them. The developed backcasting framework integrates 3D physics-based simulations with a Long-Short Term Memory (LSTM)surrogate model and SHapely Additive exPlanations (SHAP) interpretation. The combination captures temporal water temperature dynamics and quantifies the contributions of different drivers to elevated water temperature releases. As proof of concept, these methods are …

Quantifying Biocrust Evaporation In Arid Lands By Combining Thermal Imaging And Lysimeter Measurements, Rebekah C. Magness

UNLV Theses, Dissertations, Professional Papers, and Capstones

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 …

Climate Change And Hydropower Development Impacts In The Lower Mekong Basin, Nudthawud Homtong

UNLV Theses, Dissertations, Professional Papers, and Capstones

The Mekong River Basin is vital to East and Southeast Asia, supporting over 60 million people and sustaining critical ecological systems. However, the basin faces dual threats from climate change and hydropower development, jeopardizing its ecological balance, hydrological patterns, and resource reliability. This research focuses on the Lower Mekong Basin (LMB), where aggressive hydropower expansion and climate variability have intensified concerns about sustainable water management. The study is divided into three interconnected parts. Part I examines spatial and temporal precipitation patterns in the Chi-Mun Basin (CMB) and Lower Mekong River (LMR) from 1950 to 2008, using linear regression and Mann-Kendall …

Biochar/Hydrochar Applications In Disinfection Byproduct Removal For Drinking Water, Ashleu Mussio Marquez, Donna Rouhani, Ismail Abdulraheem, Kers Ung-Watson, Ahmadreza Khatamgooya, Scarlet Nelson, Dr. Jaeyun Moon, Dr. Erica Marti

Undergraduate Research Symposium Posters

This project aims to investigate the process of disinfection byproduct (DBP) removal in drinking water, looking into the applications of biochar and hydrochar, which are low cost and environmentally sustainable adsorbents. These carbon-based adsorbents are derived from agricultural waste biomass, such as walnut shells. These adsorbents will be used to capture and remove contaminants in water, such as DBPs. DBPs are formed when chemical disinfectants react with organic and inorganic substances naturally present in water. The targeted DBPs for adsorption include trihalomethanes, haloacetic acids, haloacetonitriles, and nitrosamines. An example of high concentration DBP formation is during emergency chlorination, where excess …

Image Processing Techniques For Water Droplet Penetration Time And Contact Angle Estimation, Sai Balaji Jai Kumar

UNLV Theses, Dissertations, Professional Papers, and Capstones

Water droplet behavior on soil surfaces plays a critical role in numerous environmental processes, including soil erosion, hydrological dynamics, and ecosystem health. Accurate characterization of soil water repellency, quantified by parameters such as water droplet penetration time (WDPT) and contact angles (WDCA), is essential for informed decision-making in agricultural management, forestry practices, and land-use planning. Despite the significance of these parameters, challenges exist in reliably estimating them due to the complex and dynamic nature of soil-water interactions. This thesis address challenges in estimating WDPT and WDCA, by leveraging state-of-the-art image processing techniques and machine learning algorithms. The research focuses on …

Effects Of Climate Change On (Semi)-Arid Ecosystems In The Southwestern United States, Charlotte Van Der Nagel

UNLV Theses, Dissertations, Professional Papers, and Capstones

Climate change is considered amongst the most severe threats to terrestrial and aquatic ecosystems globally. Ecosystems in the southwestern United States have specifically been impacted by intense drought conditions since 2000. Higher temperatures combined with altered precipitation stresses many ecosystems; however, ecosystem specific responses to such stressors may vary. Here, the effects of climate change on semi-arid ecosystems are analyzed for some of the most vulnerable ecosystems in the southwestern United States: lacustrine, riparian, and dryland ecosystems.

Lakes and reservoirs in arid environments often serve as drinking water sources and recreational areas where high water quality is essential. Climate change …

Investigating Controls On Temporal And Spatial Variation Of Dissolved Uranium At Springs In Horn Creek Drainage, Grand Canyon National Park, Arizona, Usa, Collin Davidson

UNLV Theses, Dissertations, Professional Papers, and Capstones

Groundwater is a critical resource in the Grand Canyon, providing water to local communities, millions of annual visitors, and ecosystems. One major concern for this critical resource is the potential for uranium contamination in conjunction with uranium mining efforts. Upper Horn Bedrock Spring (UHB) in the Horn Creek drainage of the Grand Canyon sits below the oldest uranium mine in the region, Orphan Lode mine. UHB spring contains the highest concentration of dissolved uranium in the region, eclipsing the Maximum Contaminant Level (MCL) set by the USEPA by an order of magnitude on average. This research and recent collaboration with …

Water Efficiency & Sustainability In The Mountain West, 2022, Zachary Billot, Caitlin J. Saladino, William E. Brown Jr.

Environment

This fact sheet analyzes the effectiveness of state-level policies related to water usage, conservation, and sustainability for the Mountain West states of Arizona, Colorado, Nevada, New Mexico, and Utah in 2022. The original data are published in the “2022 State Policy Scorecard for Water Efficiency and Sustainability” report written by the Alliance for Water Efficiency.

Coexistence Of Vitreous And Crystalline Phases Of H2o At Ambient Temperature, Ali K. Shargh, Aude Picard, Rostislav Hrubiak, Dongzhou Zhang, Russell J. Hemley, Shanti Deemyad, Niaz Abdolrahim, Saveez Saffarian

Life Sciences Faculty Research

Formation of vitreous ice during rapid compression of water at room temperature is important for biology and the study of biological systems. Here, we show that Raman spectra of rapidly compressed water at greater than 1 GPa at room temperature exhibits the signature of high-density amorphous ice, whereas the X-ray diffraction (XRD) pattern is dominated by crystalline ice VI. To resolve this apparent contradiction, we used molecular dynamics simulations to calculate full vibrational spectra and diffraction patterns of mixtures of vitreous ice and ice VI, including embedded interfaces between the two phases. We show quantitatively that Raman spectra, which probe …

Cumulative Infiltration And Infiltration Rate Prediction Using Optimized Deep Learning Algorithms: A Study In Western Iran, Mahdi Panahi, Khabat Khosravi, Sajjad Ahmad, Somayeh Panahi, Salim Heddam, Assefa M. Melesse, Ebrahim Omidvar, Chang Wook Lee

Civil and Environmental Engineering and Construction Faculty Research

Study region: Sixteen different sites from two provinces (Lorestan and Illam) in the western part of Iran were considered for the field data measurement of cumulative infiltration, infiltration rate, and other effective variables that affect infiltration process. Study focus: Soil infiltration is recognized as a fundamental process of the hydrologic cycle affecting surface runoff, soil erosion, and groundwater recharge. Hence, accurate prediction of the infiltration process is one of the most important tasks in hydrological science. As direct measurement is difficult and costly, and empirical models are inaccurate, the current study proposed a standalone, and optimized deep learning algorithm of …

Extreme Event Reconstructions For The Upper Fraser River Basin, British Columbia, Canada, Inga K. Homfeld

UNLV Theses, Dissertations, Professional Papers, and Capstones

Spring freshets and summer droughts have recently worsened in the Fraser River Basin, British Columbia, Canada, with significant impacts to the keystone Pacific salmon populations, the food and economic sovereignty of over eighty First Nations, and the western Canadian economy. These extreme events present a potential risk since, unlike many large and less hydroclimatically-complex and/or empounded watersheds, the Fraser River Basin is susceptible to a combination of unregulated spring freshet and summer drought events even within the same year. A major limitation for understanding past and future extreme event risk in the Fraser River Basin is that observational streamflow datasets …

Flow Topology In The Confluence Of An Open Channel With Lateral Drainage Pipe, Mohammad Nazari-Sharabian, Moses Karakouzian, Donald Hayes

Geoscience Faculty Research

The purpose of this paper is to develop design guidelines for flood control channel height in the vicinity of the confluence of a submerged drainage pipe and a flood control channel. The water exchange in the confluence of an open channel with a lateral drainage pipe produces unique hydraulic characteristics, ultimately affecting the water surface elevation in the channel. An accurate prediction of the water surface elevation is essential in the successful design of a high-velocity channel. By performing several experiments, and utilizing a numerical model (FLOW-3D), this study investigated the impact of submerged lateral drainage pipe discharges into rectangular …

Evidence For Sodium-Rich Alkaline Water In The Tagish Lake Parent Body And Implications For Amino Acid Synthesis And Racemization, Lee F. White, Kimberly T. Tait, Brian Langelier, Elizabeth A. Lymer, Ana Černok, Tanya V. Kizovski, Chi Ma, Oliver Tschauner, Richard I. Nicklin

Geoscience Faculty Research

Understanding the timing and mechanisms of amino acid synthesis and racemization on asteroidal parent bodies is key to demonstrating how amino acids evolved to be mostly left-handed in living organisms on Earth. It has been postulated that racemization can occur rapidly dependent on several factors, including the pH of the aqueous solution. Here, we conduct nanoscale geochemical analysis of a framboidal magnetite grain within the Tagish Lake carbonaceous chondrite to demonstrate that the interlocking crystal arrangement formed within a sodium-rich, alkaline fluid environment. Notably, we report on the discovery of Na-enriched subgrain boundaries and nanometer-scale Ca and Mg layers surrounding …

Water On Mars—A Literature Review, Mohammad Nazari-Sharabian, Mohammad Aghababei, Moses Karakouzian, Mehrdad Karami

Civil and Environmental Engineering and Construction Faculty Research

To assess Mars’ potential for both harboring life and providing useable resources for future human exploration, it is of paramount importance to comprehend the water situation on the planet. Therefore, studies have been conducted to determine any evidence of past or present water existence on Mars. While the presence of abundant water on Mars very early in its history is widely accepted, on its modern form, only a fraction of this water can be found, as either ice or locked into the structure of Mars’ plentiful water-rich materials. Water on the planet is evaluated through various evidence such as rocks …

An Evaluation Of Bank Storage At Lake Mead Reservoir In The Southwest United States, Jon Woodrow Wilson

UNLV Theses, Dissertations, Professional Papers, and Capstones

A water balance model is employed at Lake Mead to monitor and verify changing hydrology that affects total volume at the reservoir. Bank storage, which is defined as the volume of water captured in permeable lithologic layers subject to changes induced by contact and proximity to an open waterbody, is one component that is updated regularly and is based upon data and methods that were developed in the 1960’s from observations made within the first 30 years of the reservoir's maturation. Since this period, the reservoir has undergone further development and a current understanding of additional hydrologic affects to bank …

Infiltration Into Water-Repellent Sand: The Role Of Sorptivity, Rose Marie Shillito

UNLV Theses, Dissertations, Professional Papers, and Capstones

Soil water repellency (SWR) is believed to contribute to the increased potential for post-fire runoff and erosion. Currently, no quantitative method exists to account for SWR in physically-based runoff models. A physically-based model incorporating SWR (through the contact angle) in the infiltration parameter, sorptivity, was developed. The model was tested and verified with controlled laboratory tests on a fully characterized sand treated to create various degrees of SWR. The ability to create the wetting water characteristic curve for untreated and treated sand, appropriate for the infiltration process, was presented. Additionally, the ability to measure sorptivity with widely used infiltration tests …

The Impact Of Advanced Treatment Technologies On The Engery Use In Satellite Water Reuse Plants, Jonathan R. Bailey, Sajjad Ahmad, Jacimaria Batista

Civil and Environmental Engineering and Construction Faculty Research

With an ever-increasing world population and the resulting increase in industrialization and agricultural practices, depletion of one of the world’s most important natural resources, water, is inevitable. Water reclamation and reuse is the key to protecting this natural resource. Water reclamation using smaller decentralized wastewater treatment plants, known as satellite water reuse plants (WRP), has become popular in the last decade. Reuse plants have stricter standards for effluent quality and require a smaller land footprint (i.e., real estate area). They also require additional treatment processes and advanced treatment technologies. This greatly increases the energy consumption of an already energy intensive …

Utility Of Bench Scale Sand Tank Experiments At Assessing Permeable Reactive Barrier Design, Brandon Meier

UNLV Theses, Dissertations, Professional Papers, and Capstones

The objective of this work was to evaluate the utility of bench scale sand tank experiments at assessing permeable reactive barrier (PRB) design. Our criteria for meeting this goal was that differences between PRB designs could be identified solely by measuring concentration in outflow from the sand tank models. For our PRB designs (funnel-and-gate, staggered wells, and parallel bars), numerical simulations clearly showed that PRB design had a quantifiable effect on outflow concentration, provided that the solute reacted with the PRB materials. Conversely, use of a conservative (non-reactive) solute did not allow us to discern between PRB design alternatives. Employing …

Bringing Statistical Learning Machines Together For Hydro-Climatological Predictions - Case Study For Sacramento San Joaquin River Basin, California, Balbhadra Thakur, Ajay Kalra, Sajjad Ahmad, Kenneth W. Lamb, Venkat Lakshmi

Civil and Environmental Engineering and Construction Faculty Research

Study region: Sacramento San Joaquin River Basin, California Study focus: The study forecasts the streamflow at a regional scale within SSJ river basin with largescale climate variables. The proposed approach eliminates the bias resulting from predefined indices at regional scale. The study was performed for eight unimpaired streamflow stations from 1962–2016. First, the Singular Valued Decomposition (SVD) teleconnections of the streamflow corresponding to 500 mbar geopotential height, sea surface temperature, 500 mbar specific humidity (SHUM500), and 500 mbar U-wind (U500) were obtained. Second, the skillful SVD teleconnections were screened non-parametrically. Finally, the screened teleconnections were used as the streamflow predictors …

Evaluating The Sustainability Of Indirect Potable Reuse And Direct Potable Reuse: A Southern Nevada Case Study, Sajjad Ahmad, Cory Dow, Krystyna Stave, Daniel Gerrity

Civil and Environmental Engineering and Construction Faculty Research

This case study presents a framework for evaluating the sustainability of indirect potable reuse (IPR) and direct potable reuse (DPR) in Las Vegas, Nevada. A system dynamics model was developed to simulate population growth, water supply, water quality, energy costs, net present worth (NPW), and greenhouse gas (GHG) emissions. The model confirmed that DPR could achieve a net reduction in energy costs of up to US$250 million while still ensuring an adequate water supply. However, the high NPW of DPR ($1.0–$4.0 billion) relative to the status quo IPR approach ($0.6 billion) represents a significant economic hurdle, although future monetization of …

Twenty-Three Unsolved Problems In Hydrology (Uph) -- A Community Perspective, Günter Blöschl, Marc F.P. Bierkens, Antonio Chambel, Christophe Cudennec, Georgia Destouni, Aldo Fiori, James W. Kirchner, Jeffrey J. Mcdonnell, Hubert H.G. Savenjie, Murugesu Sivapalan, Christine Stumpp, Elena Toth, Elena Volpi, Gemma Carr, Claire Lupton, Jose Salinas, Borbala Szeles, Alberto Viglione, Hafzullah Aksoy, Scott T. Allen, Anam Amin, Vazken Andreassian, Berit Arheimer, Santosh K. Aryal, Victor Baker, Earl Bardsley, Marlies H. Barendrecht, Alena Bartosova, Okke Batelaan, Wouter R. Berghuijs, Keith Beven

Geoscience Faculty Research

This paper is the outcome of a community initiative to identify major unsolved scientific problems in hydrology motivated by a need for stronger harmonisation of research efforts. The procedure involved a public consultation through online media, followed by two workshops through which a large number of potential science questions were collated, prioritised, and synthesised. In spite of the diversity of the participants (230 scientists in total), the process revealed much about community priorities and the state of our science: a preference for continuity in research questions rather than radical departures or redirections from past and current work. Questions remain focused …

Assessing Simulated Transmissivity In Numerical Flow Models Of Complex Hydrogeology, Afan Tarar

UNLV Theses, Dissertations, Professional Papers, and Capstones

Accurately extracting a meaningful transmissivity, a target value within one order of magnitude of field estimates, in numerical models poses a significant challenge when modeling complex groundwater systems. Aquifer transmissivity is directly proportional to the aquifer thickness and the estimated aquifer hydraulic conductivity. In complex geologic conditions (especially in fractured systems) with multiple heterogeneous and anisotropic hydrogeologic units, transmissivity can vary over several orders of magnitude.

To extract a meaningful value of transmissivity from a numerical model, a simple five-layer MODFLOW model was constructed. Each layer in the model was assigned a fixed hydraulic conductivity and thickness. The model simulates …

Multi-Resolution Spatio-Temporal Change Analyses Of Hydro-Climatological Variables In Association With Large-Scale Oceanic-Atmospheric Climate Signals, Kazi Ali Tamaddun

UNLV Theses, Dissertations, Professional Papers, and Capstones

The primary objective of the work presented in this dissertation was to evaluate the change patterns, i.e., a gradual change known as the trend, and an abrupt change known as the shift, of multiple hydro-climatological variables, namely, streamflow, snow water equivalent (SWE), temperature, precipitation, and potential evapotranspiration (PET), in association with the large-scale oceanic-atmospheric climate signals. Moreover, both observed datasets and modeled simulations were used to evaluate such change patterns to assess the efficacy of the modeled datasets in emulating the observed trends and shifts under the influence of uncertainties and inconsistencies. A secondary objective of this study was to …

Pacific Southwest United States Holocene Droughts And Pluvials Inferred From Sediment Δ18o (Calcite) And Grain Size Data (Lake Elsinore, California), Matthew E.C. Kirby, William Paul Patterson, Matthew Lachniet, James A. Noblet, Michael A. Anderson, Kevin Nichols, Judith Avila

Geoscience Faculty Research

Records of past climate can inform us on the natural range and mechanisms of climate change. In the arid Pacific southwestern United States (PSW), which includes southern California, there exist a variety of Holocene records that can be used to infer past winter conditions (moisture and/or temperature). Holocene records of summer climate, however, are rare from the PSW. In the future, climate changes due to anthropogenic forcing are expected to increase the severity of drought in the already water stressed PSW. Hot droughts are of considerable concern as summer temperatures rise. As a result, understanding how summer conditions changed in …

Modeling Error Learning Based Post-Processor Framework For Hydrologic Models Accuracy Improvement, Rui Wu, Lei Yang, Chao Chen, Sajjad Ahmad, Sergiu M. Dascalu, Frederick C. Harris Jr.

Civil and Environmental Engineering and Construction Faculty Research

This paper studies how to improve the accuracy of hydrologic models using machine learning models as postprocessors and presents possibilities to reduce the workload to create an accurate hydrologic model by removing the calibration step. It is often challenging to develop an accurate hydrologic model, due to the time-consuming model calibration procedure and the non-stationarity of hydrologic data. Our findings show that the errors of hydrologic models are correlated with model 5 inputs. Thus motivated, we propose a modeling error learning based post-processor framework by leveraging this correlation to improve the accuracy of a hydrologic model. The key idea is …

Testing An Improved Method For Estimating The Unsaturated Hydraulic Conductivity Of Moderately Dry Soils, Sara Gedo

UNLV Theses, Dissertations, Professional Papers, and Capstones

Prediction of water movement in the vadose zone requires knowledge of either the unsaturated hydraulic conductivity, K(θ), or the hydraulic diffusivity, D(θ), of the soil as a function of the moisture content. However, both K(θ) and D(θ) are difficult to obtain for moderately dry soils because the tests are time consuming and expensive. In order to address this issue, Globus and Gee (1995) developed a “heat pipe” method that allowed for the direct estimation of D(θ) and K(θ) for moderately dry soils on relatively short time scales. They proposed that exposing a sealed horizontal soil column to a steady thermal …

Relationship Between Ocean-Atmospheric Climate Variables And Regional Streamflow Of The Conterminous United States, Swastik Bhandari, Ajay Kalra, Kazi Tamaddun, Sajjad Ahmad

Civil and Environmental Engineering and Construction Faculty Research

Understanding the interconnections between oceanic-atmospheric climate variables and regional streamflow of the conterminous United States may aid in improving regional long lead-time streamflow forecasting. The current research evaluates the time-lagged relationship between streamflow of six geographical regions defined from National Climate Assessment and sea surface temperature (SST), 500-mbar geopotential height (Z500), 500-mbar specific humidity (SH500), and 500-mbar east-west wind (U500) of the Pacific and the Atlantic Ocean using singular value decomposition (SVD). The spatio-temporal correlation between streamflow and SST was developed first from SVD and thus obtained correlation was later associated with Z500, SH500, and U500 separately to evaluate the …

Management Of An Urban Stormwater System Using Projected Future Scenarios Of Climate Models: A Watershed-Based Modeling Approach, Ranjeet Thakali, Ajay Kalra, Sajjad Ahmad, Kamal Qaiser

Civil and Environmental Engineering and Construction Faculty Research

Anticipating a proper management needs for urban stormwater due to climate change is becoming a critical concern to water resources managers. In an effort to identify best management practices and understand the probable future climate scenarios, this study used high-resolution climate model data in conjunction with advanced statistical methods and computer simulation. Climate model data from the North American Regional Climate Change Assessment Program (NARCCAP) were used to calculate the design storm depths for the Gowan Watershed of Las Vegas Valley, Nevada. The Storm Water Management Model (SWMM), developed by the Environmental Protection Agency (EPA), was used for hydrological modeling. …

Analyses Of Streamflow Change Patterns And Correlation Of These Changes With Sea-Surface Temperature Fluctuations, Kazi Ali Tamaddun

UNLV Theses, Dissertations, Professional Papers, and Capstones

This thesis presents a comprehensive statistical analysis that determines the direction, rate, and interval of significant streamflow change patterns in the continental U.S. and correlates these changes with sea-surface temperature fluctuations. First, by using two non-parametric tests, namely, the Mann-Kendall trend test and the Pettitt’s test, the presence of long-term trends and abrupt shifts were determined at 10% significance level over continuously adjustable periods that stretched from 1903 to 2012. Modified versions of the tests were applied to account for the presence of persistence (autocorrelation) in data. Theil-Sen slope was determined to evaluate the rate of change across multiple temporal …