Physical Sciences and Mathematics Commons^™

Understanding The Zonal Variability In Cmip6 Projections Of Sahelian Precipitation, Emmanuel Ogwuche Audu

Department of Earth and Atmospheric Sciences: Dissertations, Theses, and Student Research

The uncertainty in model projections of future precipitation across the Sahel has persisted across many generations of Earth System Models (ESMs), with some models predicting drying and others moistening across this region. These discrepancies in future projections pose a challenge for stakeholders and decision makers. Many projections of Sahel precipitation found in the ESMs participating in the sixth phase of Coupled Model Intercomparison Project (CMIP6) show a zonal dipole in precipitation trend, with moistening across the Central and Eastern Sahel and drying projected for the Western Sahel. Previous studies have connected precipitation variability across the Sahel to changes in various …

Water Whiplash In Mediterranean Regions Of The World, Citlalli Madrigal, Rama Bedri, Thomas Piechota, Wenzhao Li, Glenn Tootle, Hesham El-Askary

Biology, Chemistry, and Environmental Sciences Faculty Articles and Research

The presence of weather and water whiplash in Mediterranean regions of the world is analyzed using historical streamflow records from 1926 to 2023, depending on the region. Streamflow from the United States (California), Italy, Australia, Chile, and South Africa is analyzed using publicly available databases. Water whiplash—or the rapid shift of wet and dry periods—are compared. Wet and dry periods are defined based on annual deviations from the historical record average, and whiplash occurs when there is an abrupt change that overcomes an accommodated deficit or surplus. Of all the stations, there are more dry years (56%) than wet years …

Water-Level And Recoverable Water In Storage Changes, High Plains Aquifer, Predevelopment To 2019 And 2017 To 2019, Virginia L. Mcguire, Kellan R. Strauch

United States Geological Survey: Water Reports and Publications

The High Plains aquifer underlies 111.8 million acres (about 175,000 square miles) in parts of eight States: Colorado, Kansas, Nebraska, New Mexico, Oklahoma, South Dakota, Texas, and Wyoming. Water-level declines began in parts of the High Plains aquifer soon after the beginning of substantial groundwater irrigation (about 1950). This report presents water-level changes and change in recoverable water in storage in the High Plains aquifer from predevelopment (about 1950) to 2019 and from 2017 to 2019.

Water-level changes from predevelopment to 2019, by well, ranged from a rise of 86 feet to a decline of 265 feet; the range for …

Stage And Discharge Prediction From Documentary Time-Lapse Imagery, Kenneth W. Chapman, Troy E. Gilmore, Mehrube Mehrubeoglu, Christian D. Chapman, Aaron R. Mittelstet, John E. Stranzl Jr.

Department of Biological Systems Engineering: Papers and Publications

Imagery from fixed, ground-based cameras is rich in qualitative and quantitative information that can improve stream discharge monitoring. For instance, time-lapse imagery may be valuable for filling data gaps when sensors fail and/or during lapses in funding for monitoring programs. In this study, we used a large image archive (> 40,000 images from 2012 to 2019) from a fixed, ground-based camera that is part of a documentary watershed imaging project (https://plattebasintimelapse.com/). Scalar image features were extracted from daylight images taken at one-hour intervals. The image features were fused with United States Geological Survey stage and discharge data as …

Enhancing Urban Water Quality Through Biological-Chemical Treatment: Aquatic Macroinvertebrate Community And Temporal Chlorophyll-A Response, Matthew Chaffee

Department of Biological Systems Engineering: Dissertations and Theses

With a growing human population, urbanization is impeding a plethora of natural waterways. Of these, urban ponds play a vital role in nutrient sequestration, flood prevention, and habitat sanctuaries. However, nutrient loading can reduce habitat effectiveness and promote harmful algae blooms. To reduce internal nutrient loads, a biological-chemical treatment strategy consisting of floating treatment wetlands (FTWs) and lanthanum were applied to two urban retention ponds, Densmore and Wilderness Ridge Ponds. To measure effectiveness, chlorophyll-a samples were collected and correlated with Sentinel-2. A novel band algorithm termed 3BR1 produced a strong correlation (R² = 0.72) to physical chlorophyll-a …

The Seasonal Origins And Ages Of Water Provisioning Streams And Trees In A Tropical Montane Cloud Forest, Emily Burt, Gregory R. Goldsmith, Roxanne M. Cruz-De Hoyos, Adan Julian Ccahuana Quispe, A. Joshua West

Biology, Chemistry, and Environmental Sciences Faculty Articles and Research

Determining the sources of water provisioning streams, soils, and vegetation can provide important insights into the water that sustains critical ecosystem functions now and how those functions may be expected to respond given projected changes in the global hydrologic cycle. We developed multi-year time series of water isotope ratios (δ¹⁸O and δ²H) based on twice-monthly collections of precipitation, lysimeter, and tree branch xylem waters from a seasonally dry tropical montane cloud forest in the southeastern Andes mountains of Peru. We then used this information to determine indices of the seasonal origins, the young water fractions …

Comparison Of Ceneb And Cohyst Hydrologic Models Within A Common Domain In Central Nebraska, William R. Moak

Department of Earth and Atmospheric Sciences: Dissertations, Theses, and Student Research

The Nebraska Department of Natural Resources (NDNR) has developed several hydrologic models to help effectively manage water resources in the state. These models guide water managers to allocate surface and groundwater supplies to a range of uses (irrigation, environmental protection, interstate water agreements) and evaluate the impacts of changes to the surface water-groundwater system (e.g., new wells, evolving recharge patterns). Two such models, the Central Nebraska (CENEB) model and the Cooperative Hydrology Study (COHYST) model cover north central and south central Nebraska, respectively, but the model domains overlap along a west-east strip between the Platte and Loup Rivers, enabling direct …

Examining The Corn Seedling Emergence–Temperature Relationship For Recent Hybrids: Insights From Experimental Studies, Sahila Beegum, Charles Hunt Walne, Krishna N. Reddy, Vangimalla Reddy, Kambham Raja Reddy

Nebraska Water Center: Faculty Publications

Corn seedling emergence is a critical factor affecting crop yields. Accurately predicting emergence is crucial for precise crop growth and development simulation in process-based crop models. While various experimental studies have investigated the relationship between corn seedling emergence and temperature, there remains a scarcity of studies focused on newer corn hybrids. In the present study, statistical models (linear and quadratic functional relationships) are developed based on the seedling emergence of ten current corn hybrids, considering soil and air temperatures as influencing factors. The data used for model development are obtained from controlled soil plant atmospheric research chamber experiments focused on …

Analysis Of Wastewater Samples To Explore Community Substance Use In The United States: Pilot Correlative And Machine Learning Study, Marie A. Severson, Sathaporn Onanong, Alexandra Dolezal, Shannon L. Bartelt-Hunt, Daniel D. Snow, Lisa M. Mcfadden

Nebraska Water Center: Faculty Publications

Background: Substance use disorder and associated deaths have increased in the United States, but methods for detecting and monitoring substance use using rapid and unbiased techniques are lacking. Wastewater-based surveillance is a cost-effective method for monitoring community drug use. However, the examination of the results often focuses on descriptive analysis.

Objective: The objective of this study was to explore community substance use in the United States by analyzing wastewater samples. Geographic differences and commonalities of substance use were explored.

Methods: Wastewater was sampled across the United States (n=12). Selected drugs with misuse potential, prescriptions, and over-the-counter drugs …

Characterization Of Environmental Levels Of Pesticide Residues In Household Air And Dust Samples Near A Bioenergy Plant Using Treated Seed As Feedstock, Jabeen Taiba, Eleanor G. Rogan, Daniel D. Snow, Chandran Achutan, Muhammad Zahid

Nebraska Water Center: Faculty Publications

Exposure to neonicotinoid insecticides is associated with adverse human health outcomes. There is environmental contamination in Saunders County, Nebraska, due to the accumulation of fungicides and insecticides from a now-closed ethanol plant using seed corn as stock. A pilot study quantified environmental contamination in nearby houses from residual pesticides by measuring dust and air (indoor/outdoor) concentrations of neonicotinoids and fungicides at the study site (households within two miles of the plant) and control towns (20–30 miles away). Air (SASS^® 2300 Wetted-Wall Air Sampler) and surface dust (GHOST wipes with 4 × 4-inch template) samples were collected from eleven study …

Leaching Performance Of Nanotechnology-Induced High-Arsenic-Bearing Tooeleite-Like Mineral Nanowaste, Arindam Malakar, Sanjit Das, Samirul Islam, Rajneesh Singh, Sugata Ray

Nebraska Water Center: Faculty Publications

For arsenic decontamination from groundwater, arsenic crystallization is becoming adopted due to its sustainability and economic benefits. However, arsenic crystallization technology is a two-step process, which makes it complex and generates hazardous waste. Successful efforts toward making it a single-step process are presented here. The addition of nanorods and ball-milled zinc sulfide nanoparticles to arsenic-contaminated water result in highly monodispersed and higharsenic- containing mineralized nanowaste with a crystalline structure similar to the mineral Tooeleite ((Fe³⁺₆(As³⁺O₃)₄SO₄(OH)₄•4H₂O)). This study reports the results of a short-term stability test …

Causes And Effects Of Shisper Glacial Lake Outburst Flood Event In Karakoram In 2022, Sandeep Kumar Mondal, Vatsal D. Patel, Rishikesh Bharti, Ramesh P. Singh

Biology, Chemistry, and Environmental Sciences Faculty Articles and Research

Karakoram Himalayas are vulnerable to glacial lake outburst floods (GLOFs), which cause catastrophic floods in the surrounding areas. The increasing natural and anthropogenic activities, especially in the Indo-Gangetic Plains at the southern flank of the towering Himalayas, could be the cause of climate change affecting the frequency of the natural hazards in the Himalayas. In the present study, a detailed analysis of the Shisper Lake breach of 7 May 2022 is carried out using satellite remote sensing. A decreasing trend in the glacial mass balance is observed between 2017 and 2021; in this period, frequent GLOF episodes occurred. A pronounced …

Reaction Steps In Heterogeneous Photocatalytic Oxidation Of Toluene In Gas Phase—A Review, Yerzhigit Tulebekov, Zhandos Orazov, Bagdat Satybaldiyev, Daniel D. Snow, Raphaël Schneider, Bolat Uralbekov

Nebraska Water Center: Faculty Publications

A review of the current literature shows there is no clear consensus regarding the reaction mechanisms of air-borne aromatic compounds such as toluene by photocatalytic oxidation. Potential oxidation reactions over TiO₂ or TiO₂-based catalysts under ultraviolet and visible (UV/VIS) illumination are most commonly considered for removal of these pollutants. Along the pathways from a model pollutant, toluene, to final mineralization products (CO₂ and H₂O), the formation of several intermediates via specific reactions include parallel oxidation reactions and formation of less-reactive intermediates on the TiO₂ surface. The latter may occupy active adsorption sites and …

The Irrigation Efficiency Trap: Rational Farm-Scale Decisions Can Lead To Poor Hydrologic Outcomes At The Basin Scale, Christina N. Morrisett, Robert W. Van Kirk, London O. Bernier, Andrea L. Holt, Chloe B. Perel, Sarah E. Null

Watershed Sciences Faculty Publications

Agricultural irrigation practices have changed through time as technology has enabled more efficient conveyance and application. In some agricultural regions, irrigation can contribute to incidental aquifer recharge important for groundwater return flows to streams. The Henrys Fork Snake River, Idaho (United States) overlies a portion of the Eastern Snake Plain Aquifer, where irrigated agriculture has occurred for over a century. Using irrigator interviews, aerial and satellite imagery, and statistical streamflow analysis, we document the impact of farm-scale decisions on basin-scale hydrology. Motivated to improve economic efficiency, irrigators began converting from surface to center-pivot sprinkler irrigation in the 1950s, with rapid …

Adsorptive–Photocatalytic Performance For Antibiotic And Personal Care Product Using Cu0.5Mn0.5Fe2O4, Chanat Chokejaroenrat, Chainarong Sakulthaew, Athaphon Angkaew, Apiladda Pattanateeradetch, Wuttinun Raksajit, Kanokwan Teingtham, Piyaporn Phansak, Pawee Klongvessa, Daniel D. Snow, Clifford E. Harris, Steven Comfort

Nebraska Water Center: Faculty Publications

The amount of antibiotics and personal care products entering local sewage systems and ultimately natural waters is increasing and raising concerns about long-term human health effects. We developed an adsorptive photocatalyst, Cu_0.5Mn_0.5Fe₂O₄ nanoparticles, utilizing co-precipitation and calcination with melamine, and quantified its efficacy in removing paraben and oxytetracycline (OTC). During melamine calcination, Cu_0.5Mn_0.5Fe₂O₄ recrystallized, improving material crystallinity and purity for the adsorptive–photocatalytic reaction. Kinetic experiments showed that all four parabens and OTC were removed within 120 and 45 min. We found that contaminant adsorption and reaction …

Incorporation Of Carbon Dioxide Production And Transport Module Into A Soil-Plant-Atmosphere Continuum Model, Sahila Beegum, Wenguang Sun, Dennis Timlin, Zhuangji Wang, David Fleisher, Vangimalla R. Reddy, Chittaranjan Ray

Nebraska Water Center: Faculty Publications

Carbon dioxide release from agricultural soils is influenced by multiple factors, including soil (soil properties, soil-microbial respiration, water content, temperature, soil diffusivity), plant (carbon assimilation, rhizosphere respiration), atmosphere (climate, atmospheric carbon dioxide), etc. Accurate estimation of the carbon dioxide (CO₂) fluxes in the soil and soil respiration (CO₂ flux between soil and atmosphere) requires a process-based modeling approach that accounts for the influence of all these factors. In this study, a module for CO₂ production via root and microbial respiration and diffusion-based carbon dioxide transport is developed and integrated with MAIZSIM (a process-based maize crop growth …

Small Community Water Systems Have The Highest Prevalence Of Mn In Drinking Water In California, Usa, Miranda Aiken, Samantha C. Ying

Biology, Chemistry, and Environmental Sciences Faculty Articles and Research

Manganese (Mn) is currently regulated as a secondary contaminant in California, USA; however, recent revisions of the World Health Organization drinking water guidelines have increased regulatory attention of Mn in drinking water due to increasing reports of neurotoxic effects in infants and children. In this study, Mn concentrations reported to California’s Safe Drinking Water Information System were used to estimate the potentially exposed population within California based on system size. We estimate that between 2011 and 2021, over 525,000 users in areas with reported Mn data are potentially exposed to Mn concentrations exceeding the WHO health-based guideline (80 μg L …

Improving The Cotton Simulation Model, Gossym, For Soil, Photosynthesis, And Transpiration Processes, Sahila Beegum, Dennis Timlin, Kambham Raja Reddy, Vangimalla Reddy, Wenguang Sun, Zhuangji Wang, David Fleisher, Chittaranjan Ray

Nebraska Water Center: Faculty Publications

GOSSYM, a mechanistic, process-level cotton crop simulation model, has a two-dimensional (2D) gridded soil model called Rhizos that simulates the below-ground processes daily. Water movement is based on gradients of water content and not hydraulic heads. In GOSSYM, photosynthesis is calculated using a daily empirical light response function that requires calibration for response to elevated carbon dioxide ( CO₂). This report discusses improvements made to the GOSSYM model for soil, photosynthesis, and transpiration processes. GOSSYM’s predictions of below-ground processes using Rhizos are improved by replacing it with 2DSOIL, a mechanistic 2D finite element soil process model. The photosynthesis …

Occurrence Of Radionuclides And Hazardous Elements In The Transboundary River Basin Kyrgyzstan–Kazakhstan, Mariya A. Severinenko, Vladimir P. Solodukhin, Bekmamat M. Djenbaev, The National Academy Of Science Of The Kyrgyz Republic G. Lennik, Baktiyar T. Zholboldiev, Daniel D. Snow

Nebraska Water Center: Faculty Publications

Important for irrigation, the transboundary river basin between Kyrgyzstan and Kazakhstan is vulnerable to geochemical and anthropogenic sources of pollution. The use of water use indices, together with measurements of the elemental and radionuclide composition of the water and bottom sediments, provides a means for evaluating the continued use of the water from this region. Recent monitoring shows the highest concentrations of hazardous contaminants include lead and thorium contained in the bottom and banks of the Kichi-Kemin River. These contaminants are likely remnants of an accidental spill at the Aktyuz tailing dump in 1964. The specific activity of the Th-232 …

Mixing Regimes In A Cluster Of Seven Maar Lakes In Tropical Monsoon Asia, Milette U. Mendoza, Jaydan I. Aguilar, Karol Sophia Agape R. Padilla, Rey Donne S. Papa, Noboru Okuda

Environmental Science Faculty Publications

The 7 maar lakes of San Pablo are a cluster of small volcanic lakes on Luzon Island; Philippines. These lakes; which are heavily utilized for aquaculture and ecotourism; usually experience fish kills that coincide with the northeast monsoon (NEM). This study explores limnophysical processes; particularly mixing regimes; in the lakes in relation to prevailing monsoons. We monitored monthly vertical and seasonal profiles of water temperature; salinity; conductivity; and dissolved oxygen from October 2016 to December 2018. Three types of mixing regimes were observed among the lakes; which have similar surface areas but different depths: polymixis in the shallowest; warm monomixis …

Hydropower To The People: Implications Of A Comparative Macroinvertebrate Study On Either Side Of The Central Hidroeléctrica Topo In Tungurahua, Ecuador, Grace Mazur

Independent Study Project (ISP) Collection

This study uses macroinvertebrates as bioindicators to assess the water quality upstream and downstream of a hydroelectric project in Ecuador’s eastern cloud forest. Ecuador has increasingly turned to hydropower to supply its energy needs as pressure mounts to turn away from fossil fuels. This transition has been realized on the Río Topo, located in the province of Tungurahua. This study aims to determine how the Central Hidroeléctrica Topo (CHT), a diversion hydroelectric project (HEP) constructed on the Río Topo in the 2010s, has affected the water quality of the river. Samples were taken of benthic (bottom-dwelling) macroinvertebrates in the Río …

Anuran Species Diversity And Abundance Between Three Locations In El Valle De Antón, Coclé, Panamá, Xena Gehring

Independent Study Project (ISP) Collection

Panama is an incredibly biodiverse country that houses 230 species of amphibians including 188 species of frogs, 35 of which are endemic to Panama. Commonly found in terrestrial and aquatic habitats, frogs play a very important role in the regulation of insect populations and serve as a valuable food resource to other predators. The greatest threat to amphibian species at this time is Chytridiomycosis, a fungal pathogen that infects the skin and often results in death. Many species of amphibians have already gone completely extinct or are extinct in the wild due to the proliferation of this disease. The skin …

Hydrological Patterns Of The Chimborazo Reserve: Streamflow, Climate, And Glacier Recession Data Show A Loss Of Glacial Influence On The Southwestern Aspect Of The Chimborazo Volcano, Ecuador., William F. M. Patrick

Independent Study Project (ISP) Collection

The Chimborazo volcano of the central Ecuadorian Andean Cordillera (6310 m) has been shown to currently be undergoing extreme glacial recession due to climate change. For this reason, this study sought to analyze climate and glacier recession data in conjunction with streamflow from kryal (glacial-fed), rhithral (non-glacial-fed), and intermediate streams to not only evaluate the current health of Chimborazo’s glaciers, but also determine how hydrology in the region will respond to future climate change. The rate of glacial recession on the volcano was determined using satellite imagery between 1965 and 2019. Measurements of stream elevation, pH, water temperature, width, depth, …

Projected Long-Term Climate Trends Reveal The Critical Role Of Vapor Pressure Deficit For Soybean Yields In The Us Midwest, Wenguang Sun, David Fleisher, Dennis Timlin, Chittaranjan Ray, Zhuangji Wang, Sahila Beegum, Vangimalla Reddy

Nebraska Water Center: Faculty Publications

Extreme climate events including heat waves and droughts are projected to become more frequent under future climate change conditions. However, the mechanisms between soybean yields and climate factors, specifically involving variable rainfall and high heat episodes, are still unclear, particularly with respect to spatial trends in the United States (US) Midwest. A recently modified version of the model GLYCIM was used to evaluate rainfed soybean production across 12 states at a 10 km spatial resolution for three time periods (2011–2020, 2051–2060, 2091–2099) under Representative Concentration Pathway (RCP) scenarios 4.5 and 8.5. Results showed that except for the northernmost Midwest counties, …

Simulation Of Monthly Mean And Monthly Base Flow Of Streamflow Using Random Forests For The Mississippi River Alluvial Plain, 1901 To 2018, Benjamin J. Dietsch, William H. Asquith, Brian K. Breaker, Stephen M. Westenbroek, Wade H. Kress

United States Geological Survey: Water Reports and Publications

Improved simulations of streamflow and base flow for selected sites within and adjacent to the Mississippi River Alluvial Plain area are important for modeling groundwater flow because surface-water flows have a substantial effect on groundwater levels. One method for simulating streamflow and base flow, random forest (RF) models, was developed from the data at gaged sites and, in turn, was used to make monthly mean streamflow and base-flow predictions at 162 ungaged sites in the study area. Daily streamflow observations and computed base flow from 247 streamgages were used as the basis for the development of these RF models. RF …

Importance Of Snowmelt On Soil Nitrate Leaching To Groundwater – A Model Study, Sahila Beegum, Arindam Malakar, Chittaranjan Ray, Daniel D. Snow

Nebraska Water Center: Faculty Publications

The movement of nitrate to surface water bodies during snow accumulation and melting has been extensively studied, but there are only limited studies on the influence of snow processes on nitrate leaching to groundwater. The present study investigated the impact of snow processes on nitrate leaching to groundwater based on a simulation modeling approach using HYDRUS-1D. HYDRUS-1D model has a temperature threshold-based snow model in addition to water, solute, and heat simulation components. The snow component in HYDRUS-1D was previously not applied to snow simulation studies since the method does not consider a detailed physical and process-based representation of snow …

Constituent Loads And Trends In The Upper Illinois River Watershed: A Nonpoint Source Management Program Priority Watershed, Erin M. Grantz, Brian E. Haggard

Technical Reports

The Arkansas Department of Agriculture - Natural Resources Division (ANRD) has identified the Upper Illinois River Watershed (UIRW; 11110103), a hydrologic unit code (HUC) 8 watershed, located in Northwest Arkansas for prioritization by the Nonpoint Source (NPS) Management Program. URIW encompasses the Illinois River from its headwaters to the state line with Oklahoma and has been the subject of interstate disputes over water quality for decades. Nonpoint source pollution concerns in UIRW are excess nutrients from agriculture and sediment from changes in land use/land cover (LULC).

Local, state, and national groups, including the NPS Source Management Program, have invested in …

Constituent Loads And Trends In The Upper White River Basin: A Nonpoint Source Management Program Priority Watersheds, Erin M. Grantz, Brian E. Haggard

Technical Reports

The Arkansas Department of Agriculture – Natural Resources Division (ANRD) has identified the Upper White River Basin (UWRB; HUC 11010001) a hydrologic unit code (HUC) 8 watersheds, located in Northwest Arkansas, for prioritization by the Nonpoint Source (NPS) Management Program. UWRB includes Beaver Lake in its borders, the drinking water source for 1 in 6 Arkansans. Nonpoint source pollution concerns in these watersheds are excess nutrients from agriculture and sediment from changes in land use/land cover (LULC).

Local, state, and national groups, including the NPS Source Management Program, have invested in education, best management practices, and streambank restoration in the …

Time Domain Reflectometry Waveform Interpretation With Convolutional Neural Networks, Zhuangji Wang, Shan Hua, Dennis Timlin, Yuki Kojima, Songtao Lu, Wenguang Sun, David Fleisher, Robert Horton, Vangimalla R. Reddy, Katherine Tully

Nebraska Water Center: Faculty Publications

Interpreting time domain reflectometry (TDR) waveforms obtained in soils with non-uniform water content is an open question. We design a new TDR waveform interpretation model based on convolutional neural networks (CNNs) that can reveal the spatial variations of soil relative permittivity and water content along a TDR sensor. The proposed model, namely TDR-CNN, is constructed with three modules. First, the geometrical features of the TDR waveforms are extracted with a simplified version of VGG16 network. Second, the reflection positions in a TDR waveform are traced using a 1D version of the region proposal network. Finally, the soil relative permittivity values …

Home Tap Water In Nonmetropolitan Nebraska, Rebecca J. Vogt

Cornhusker Economics

Water is an important resource in Nebraska. Most of the drinking water in the state (85%) comes from groundwater sources. Public water sources are required to test their water to ensure it is safe. However, private wells are not subject to any safety or quality standards. Given that, what are the main sources of home tap water for rural Nebraskans? Do they test or treat their water? The 2022 Nebraska Rural Poll examined these questions.