Engineering Commons^™

Effect Of Spatial And Temporal Variability Of Antecedent Moisture Content On Model-Generated Runoff From An Arid Watershed, William J. Meyer

UNLV Theses, Dissertations, Professional Papers, and Capstones

Streams in the arid southwest are typically ephemeral, and stream gages are not commonly available. Consequently, runoff data from storm events is not available, and flood control facility design or other water resource related decisions are based on synthetic hydrographs. In the Mojave Desert region of Southern Nevada, the duration of storm used to develop these synthetic hydrographs is the 6 hour storm. The 6 hour storm is used to simulate high intensity summer storms. Additionally, soils information used in the calculations for these synthetic hydrographs is taken from maps that are generally developed for a broad range of issues …

Improving Ensemble Streamflow Prediction Using Interdecadal/Interannual Climate Variability, Kenneth W. Lamb

UNLV Theses, Dissertations, Professional Papers, and Capstones

The National Weather Service’s (NWS) river forecast centers provide long-term water resource forecasts for the main river basins in the U.S. The NWS creates seasonal streamflow forecasts using an ensemble prediction model called the Extended Streamflow Prediction (ESP) software. ESP creates runoff volume forecasts by taking the current observed soil moisture and snowpack conditions in the basin and applying them to historical temperature and precipitation scenarios. The ESP treats every historic input year as a likely scenario of future basin conditions. Therefore improving the knowledge about how long-term climate cycles impact streamflow can extend the forecast lead time and improve …

Analysis And Evaluation Of Safety Impacts Of Median Types And Midblock Left Turn Treatments For Urban Arterials, Timur Mauga

UNLV Theses, Dissertations, Professional Papers, and Capstones

Urban growth leads to new land-uses abutting arterials requiring driveways for their accessibility. Uncontrolled number and locations of such access points causes safety, mobility and accessibility problems. The solution to these problems is access management (AM) which controls the number and location of the access points. AM techniques are normally documented in the form of guidelines for engineers and planners to follow when implementing the techniques. However, AM guidelines may not cover every technique due to the fact that AM is still growing. For example, the current AM guideline prepared by The Nevada Department of Transportation addresses many AM techniques. …

Automated Procedures For Quantification Of Rhizosphere Physical Properties In Micro Ct Images, Natarajan S. Pillai

UNLV Theses, Dissertations, Professional Papers, and Capstones

The rhizosphere, i.e. the zone of soil immediately surrounding plant roots plays a prominent role in supplying plants with water and nutrients. However, surprisingly little is known about rhizosphere physical properties and how they affect root growth, water and nutrient uptake. The lack of non-invasive and non-destructive imaging techniques necessary to observe living roots growing in undisturbed soil have been a main reason for this shortcoming. Recent advances in synchrotron X-ray micro tomography (CMT) provide the potential to directly observe soil physical properties around living roots in-situ.In this work we develop procedures for assisting scientist to study the soil properties …

Evaluating The Impacts Of Water Conservation Policies On Water Demand, Availability And Outdoor Water Use In The Las Vegas Valley, Kamal Qaiser

UNLV Theses, Dissertations, Professional Papers, and Capstones

The Las Vegas Valley, located in the arid Southern Nevada region, with a growing population, limited water resources, and a prolonged drought, faces a challenge in meeting its future water needs. Southern Nevada Water Authority (SNWA), the main water management agency in the Valley, is focusing on water conservation to reduce water demand. Current water use is 945 lpcd (250 gpcd) which SNWA aims to reduce to 752 lpcd (199 gpcd) by 2035. Presently the indoor outdoor water use proportion is about 40:60 in the Valley. An important component of the Valley's supply are the return flow credits which SNWA …

Investigation Of Potential Pathways And Multi-Cycle Bioregeneration Of Ion-Exchange Resin Laden With Perchlorate, Mohamadali Sharbatmaleki

UNLV Theses, Dissertations, Professional Papers, and Capstones

Ion-exchange (IX) is possibly the most feasible technology for perchlorate removal and perchlorate-selective and non-selective IX resins are commercially available for this purpose. The use of both resins has shortcomings. Selective resins are incinerated after one time use, and non-selective resins produce a regenerant waste stream that contains high concentration of perchlorate. A process involving directly contacting of spent IX resin containing perchlorate with perchlorate-reducing bacteria (PRB) to bioregenerate the resin has been developed and proven recently. In this process PRB biodegrade perchlorate ions which are attached to the functional groups of the resin.

Although its feasibility has been proven, …

Performance Of Nevada’S Aggregates In Alkali-Aggregate Reactivity Of Portland Cement Concrete, Mohammad Shahidul Islam

UNLV Theses, Dissertations, Professional Papers, and Capstones

Alkali-aggregate reaction (AAR) is a form of distress that occurs in concrete and results in serviceability problems, cracks, spalling, and other deterioration mechanisms. There are two categories of AAR, namely, alkali-silica reaction (ASR) and alkali-carbonate reaction (ACR). Alkali-silica reaction is one of the most recognized deleterious phenomena in concrete, and has been a major concern since its discovery in the 1940s. The reaction which occurs between reactive silica or silicates present in some aggregates and alkalis of Portland cement produces an alkali-silica gel that expands in the presence of moisture resulting in concrete cracks. ACR is also a chemical reaction …

An Exploratory Study On Energy Consumption Of Energy Star And Non-Energy Star Homes, Prajakta Kulkarni

UNLV Theses, Dissertations, Professional Papers, and Capstones

The reduction of energy consumption is one of the economic necessities in the United States due to depleting energy sources in the world. The construction industry is stepping forward to reduce the energy consumption of buildings by efficient designs or by constructing buildings with energy efficient materials and features. In 1992, the U.S. Environmental Protection Agency (EPA) and Department of Energy (DOE) introduced the Energy Star Program to promote energy efficient products with the same or improved services. According to the EPA, Energy Star homes, which use these products, will consume 20 to 30 percent less energy than non-Energy Star …

Assessment Of Impacts To Hydroclimatology And River Operations Due To Climate Change Over The Colorado River Basin, William Paul Miller

UNLV Theses, Dissertations, Professional Papers, and Capstones

This dissertation investigated the impacts of climate change to the hydroclimatology and river and reservoir management operations within the Colorado River Basin. Preliminary research indicated observed warming trends throughout the Colorado River Basin and corresponding seasonal trends to the magnitude and timing of runoff in the Colorado River Basin. Subsequent research investigated the changing character of precipitation and corresponding impacts to streamflow over the Colorado River Basin. Analysis of snowpack telemetry (SNOTEL) stations over the American West and Colorado River Basin indicated decreasing trends in annual snowpack, often at least at the 95% confidence interval. A shorter snowpack season was …

Ion-Exchange (Ix): Arsenic And Chromium Removal From Brines And Removal Of Inorganic Contaminants By Specialty Resins, Behrang Pakzadeh

UNLV Theses, Dissertations, Professional Papers, and Capstones

Although ion exchange is highly efficient in removing inorganic contaminants, similar to other water treatment technologies, ion exchange has some drawbacks that need to be studied further. Three issues related to drawbacks of ion-exchange resins in water treatment were addressed in this research. The first issue was the influence of anionic inorganic co-contaminants including nitrate, Cr(VI), Se(VI), and As(V) on the performances of nitrate and perchlorate specialty (selective) resins in water treatment. It was found that nitrate can be removed from waters using perchlorate specialty resins, but the resin is poorly regenerated. Perchlorate was not easily removed from either nitrate …

Evaluation Of Safety Impact Of Access Management In Urban Areas, Xuecai Xu

UNLV Theses, Dissertations, Professional Papers, and Capstones

The access provided by streets and highways to adjacent lands are managed by controlling the spacings between the access points including signals, driveways, and media openings on mid-block segments, and setting the limit on the corner clearances around intersections. There have been studies on evaluating the impact of access management techniques on safety and mobility in urban areas. Samples of mid-block segments and intersections can be collected from selected arterials. Because the mid-block segments or intersections in the same arterials share the same missing information, safety and mobility on them show unique features that should be taken into account when …

Statistical Modeling And Analysis Of Injury Severity Sustained By Occupants Of Passenger Vehicles Involved In Crashes With Large Trucks, Ahmad Koupaenejad

UNLV Theses, Dissertations, Professional Papers, and Capstones

Crashes are the result of complex interactions between several factors representing driver, roadway, vehicle, and environmental characteristics. Understanding to what degree each factor contributes to the severity of a crash is not a simple task. The outcomes of crashes in the US have been an average of 42,000 deaths and 3 million injuries per year. To better understand the role of significant contributors to crashes, three sets of models using multinomial logit and one using ordered probit were calibrated. To calibrate these models, forty two independent predictor variables including driver/occupants characteristics, crash environment at the crash location, crash characteristics, and …