Fresh Water Studies Commons^™

Three-Dimensional Higher-Order Compressive Sensing For Raypath Separation In An Acoustic Waveguide, Fengyan Zhong

Journal of Marine Science and Technology–Taiwan

In an acoustic waveguide, the separation of multiple raypaths, especially close raypaths, is a challenging task in the presence of colored noise due to interference in the acoustic eld. In this paper, a three-dimensional higher-order compressive sensing method for raypath separation is proposed. The method is applied on an array-to-array experimental conguration where both emitter and reception arrays are used. With the array-to-array conguration, the raypaths are characterized by three parameters including arrival direction, departure direction, and arrival time. Furthermore, the performance of the proposed algorithm is illustrated by simulations and experiments. The numerical results based on simulation illustrate that …

Projection Of Sea Surface Temperature Based On Empirical Mode Decomposition And Its Application In Typhoon Number Forecast, Wen-Cheng Huang, Jung-Chen Lee

Journal of Marine Science and Technology–Taiwan

The primary objective of this paper is to demonstrate the applicability of empirical mode decomposition (EMD) in projecting non-stationary daily sea surface temperature (SST) series, and the other is to apply the projected series of SST to estimate the number of typhoons. The study focuses on an area ranging from 5°N~25°N and 110°E~170°E, collecting daily sea temperature data and typhoons records within this region. The findings conclusively indicate that the EMD-based data generation method proposed in this paper can effectively addresses the limitations of previous hydrological models in generating non-stationary series, signifying a significant advancement in hydrological time series modeling …

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 …

Understanding The Flow Dynamics Of The Pearl River, Ms, Through Hydrodynamic Modeling, Nahruma Mehzabeen Pieu

Master's Theses

The Pearl River brings fresh water and nutrients into Lake Borgne regulating conditions for oyster growth in estuarine waters. However, there are no flow measurement stations installed on East Pearl or West Pearl either at the river outlets or after the upstream bifurcation of the Pearl. This study aims to model the Lower Pearl River to understand the flow dynamics in the major branches, and to determine the final outflow distribution into the Mississippi Sound, aiming to improve river forcing for ocean models studying estuarine dynamics of the Mississippi Sound.

Synthetic meandering bathymetry with updated banks is developed and applied …

Drinking Water Contaminants: Lead, Bruce I. Dvorak, Becky M. Schuerman

Department of Civil and Environmental Engineering: Faculty Publications

Any lead exposure, even low levels, can be a serious health concern, especially for infants, children, and developing fetuses. This NebGuide discusses how to safely manage lead in a domestic water supply (or often referred to as a private well). This NebGuide includes discussion related to topics such as lead services lines and changes in public water supply regulations related to lead in drinking water.

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 …

Evaluation Of Hydrogeochemical Characteristics Of San Joaquin, Tulare, And Mojave Aquifers, Southern California, Maedeh Hassanvand

Graduate Theses and Dissertations

Before making attempts to enhance and manage the quality of water, a thorough understanding of these processes is necessary since the chemical quality of groundwater is impacted by a number of linked processes. This would be more important in arid and semiarid regions like the southern part of California where more rely on groundwater for agriculture and drinking water uses than the other states. As a result, fundamental knowledge of the governing processes of groundwater chemistry is required for effective water resource management. Thus, this study is primarily concerned with three aspects in Mojave, Tulare, and San Joaquin aquifers: The …

From Mountain Streams To Urban Rivers: An Assessment Of Microplastic Sources And Characteristics, Macy Gustavus

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

Plastic products are produced and discarded at an alarming rate. Bottles, bags, toys, and clothing break down into tiny plastic pieces called microplastics, ranging in size from an eraser on the top of a pencil to smaller in size than a red blood cell. Microplastics are becoming so common in the environment that they travel in the atmosphere, rivers, and ocean currents in ways that are similar to other types of Earth Systems Cycles (i.e., the water cycle). In this study, we explored microplastic sources and sinks in a freshwater river system and how seasonal changes in discharge affect how …

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 …

Silver Carp Hypophthalmichthys Molitrix Movements In The Lower Cumberland And Lower Tennessee River, Miranda Belanger

Scholars Week

Silver Carp Hypophthalmichthys molitrix are an invasive species making up a large portion of the fish biomass in the lower portions of the Tennessee River and the Cumberland River. This species is expanding its range throughout the upper portions of these rivers, beginning with Kentucky Lake and Lake Barkley. Silver Carp rarely spawn in Kentucky Lake and Lake Barkley, but they can enter these reservoirs through the lock chamber. Thus, the bottleneck created by lock chambers can be used to control expansion of invasive Silver Carp. Although Silver Carp movement patterns have been studied in other portions of the Tennessee …

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 …

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, …

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 …

Droughtscape, Spring 2023, National Drought Mitigation Center

DroughtScape: Quarterly Newsletter of the National Drought Mitigation Center (2007–2023)

DroughtScape, Spring 2023

Drinking Water Contaminants: Bacteria, Bruce I. Dvorak, Becky O. Schuerman

Department of Civil and Environmental Engineering: Faculty Publications

Testing drinking water for fecal bacteria or Escherichia coli (E. coli) is commonly used as an indicator of the presence of pathogenic microorganisms. The presence of pathogenic (disease-causing) microorganisms is a concern when considering the safety of drinking water. Pathogenic microorganisms can cause flu-like systems, intestinal infections, dysentery, hepatitis, typhoid fever, cholera, and other illnesses.

Effects Of Various Dietary Carbohydrate Sources On The Growth Performance And Body Composition Of The Dog Conch, Laevistrombus Canarium, Jen-Hong Chu

Journal of Marine Science and Technology–Taiwan

This study investigates the effects of dietary supplementation with various carbohydrate sources on the growth and dietary nutrient utilization efficiency of a 0.72-g dog conch, Laevistrombus canarium. Five treatment diets had supplementation with alpha-starch (Sta), dextrin (Dex), pullulan gum (Pg), xanthan gum (Xg), and carboxymethyl cellulose (CMC). At the end of the feeding trial, the best growth performance (weight gain, 442.23%) and diet efficiency (protein efficiency ratio, 1.25, and feed conversion ratio [FCR], 2.04) were exhibited by the dog conch fed the Sta diet, whereas the lowest growth performance was observed in the dog conch fed the Xg and CMC …

Cost Advantages Of Far East/Europe Trunk Route Deployment With Port Selection In East Asia, Tai Hui-Huang, Chang Chin-Wei

Journal of Marine Science and Technology–Taiwan

To cater to the gradually increasing sizes of ships, several traditional container ports in East Asia built deep-water wharves to attract shipping carriers to berth, a decision that is considered highly reasonable because it allows for shipping carriers to gain a cost advantage. For traditional Far East/Europe (F/E) trunk routes, shipping carriers must deploy vessels that are large enough at hub ports to maintain low transshipment costs. However, for a port to attract shipping carriers, it should be able to first meet the cargo demand of these carriers. The port would also need to improve the loading ratio to enjoy …

Influence Of Vacuum Condition On Rapid Chloride Migration (Rcm) Test For Chloride Penetration Resistance Of Concrete, Chih-Yen Lin, Chun-Fu Chang, Chung-Chia Yang

Journal of Marine Science and Technology–Taiwan

NT Build 492 regulates that the pressure be set at 7.5–37.5 torr and be maintained for 3 h for vacuum processing. This large range of acceptable vacuum pressure is awkward for research, and 3 h of pump-down time may be excessive. In this study, vacuum conditions were divided into vacuum pressure and pump-down time groups: various vacuum pressures and pump-down times were used to preprocess specimens to explore the effect of vacuum conditions on the RCM test. The salt ponding test was also conducted to identify the optimal vacuum conditions. It is shown that the relationship between vacuum pressure and …