Physical Sciences and Mathematics Commons^™

Real-Time Pm10 Emission Rates From Paved Roads By Measurement Of Concentrations In The Vehicle's Wake Using On-Board Sensors Part 2. Comparison Of Scamper, Traker™, Flux Measurements, And Ap-42 Silt Sampling Under Controlled Conditions, Dennis R. Fitz, Kurt Bullimer, Vic Etyemezian, Hampden D. Kuhns, John A. Gillies, George Nikolich, David E. James, Rodney Langston, Russell S. Merle Jr.

Civil and Environmental Engineering and Construction Faculty Research

Representative soil was evenly applied to an 800-m section of road surface. The test area was of sufficient length to allow for measurement at constant speeds of up to 72 km hr−1. SCAMPER and TRAKER™ mobile measurement vehicles made repeated test runs while an instrumented tower measured upwind-downwind horizontal PM10 flux. AP-42 methods were used to collect silt samples and calculate PM10 emission factors. Both silt loadings and vehicle speeds were varied during the experiment. Street sweeping the as-found roadway showed an initial rise in PM10 emission rates. Both TRAKER and SCAMPER measured rapid decay of PM10 emission rates after …

Changes In Snow Phenology From 1979 To 2016 Over The Tianshan Mountains, Central Asia, Tao Yang, Qian Li, Sajjad Ahmad, Hongfei Zhou, Lanhai Li

Civil and Environmental Engineering and Construction Faculty Research

Snowmelt from the Tianshan Mountains (TS) is a major contributor to the water resources of the Central Asian region. Thus, changes in snow phenology over the TS have significant implications for regional water supplies and ecosystem services. However, the characteristics of changes in snow phenology and their influences on the climate are poorly understood throughout the entire TS due to the lack of in situ observations, limitations of optical remote sensing due to clouds, and decentralized political landscapes. Using passive microwave remote sensing snow data from 1979 to 2016 across the TS, this study investigates the spatiotemporal variations of snow …

Climate Change And Eutrophication: A Short Review, Mohammad Nazari-Sharabian, Sajjad Ahmad, Moses Karakouzian

Civil and Environmental Engineering and Construction Faculty Research

Water resources are vital not only for human beings but essentially all ecosystems. Human health is at risk if clean drinking water becomes contaminated. Water is also essential for agriculture, manufacturing, energy production and other diverse uses. Therefore, a changing climate and its potential effects put more pressure on water resources. Climate change may cause increased water demand as a result of rising temperatures and evaporation while decreasing water availability. On the other hand, extreme events as a result of climate change can increase surface runoff and flooding, deteriorating water quality as well. One effect is water eutrophication, which occurs …

Estimating Annual Precipitation For The Colorado River Basin Using Oceanic-Atmospheric Oscillations, Ajay Kalra, Sajjad Ahmad

Civil and Environmental Engineering and Construction Faculty Research

Estimating long-lead time precipitation under the stress of increased climatic variability is a challenging task in the field of hydrology. A modified Support Vector Machine (SVM) based framework is proposed to estimate annual precipitation using oceanic-atmospheric oscillations. Oceanic-atmospheric oscillations, consisting of Pacific Decadal Oscillation (PDO), North Atlantic Oscillation (NAO), Atlantic Multidecadal Oscillation (AMO), and El Niño–Southern Oscillation (ENSO) for a period of 1900–2008, are used to generate annual precipitation estimates with a 1 year lead time. The SVM model is applied to 17 climate divisions encompassing the Colorado River Basin in the western United States. The overall results revealed that …

Evaluating Changes And Estimating Seasonal Precipitation For Colorado River Basin Using Stochastic Non-Parametric Disaggregation Technique, Ajay Kalra, Sajjad Ahmad

Civil and Environmental Engineering and Construction Faculty Research

Precipitation estimation is an important and challenging task in hydrology because of high variability and changing climate. This research involves (1) analyzing changes (trend and step) in seasonal precipitation and (2) estimating seasonal precipitation by disaggregating water year precipitation using a k-nearest neighbor (KNN) nonparametric technique for 29 climate divisions encompassing the Colorado River Basin. Water year precipitation data from 1900 to 2008 are subdivided into four seasons (i.e., autumn, winter, spring, and summer). Two statistical tests (Mann-Kendall and Spearman’s rho) are used to evaluate trend changes, and a rank sum test is used to identify the step change in …

The Carbon Footprint Associated With Water Management Policy Options In The Las Vegas Valley, Nevada, Eleeja Shrestha, Sajjad Ahmad, Walter Johnson, Jacimaria R. Batista

Civil and Environmental Engineering and Construction Faculty Research

A system dynamics model was developed to estimate the carbon dioxide (CO₂) emissions associated with conveyance of water from the water source to the distribution laterals of the Las Vegas Valley. In addition, the impact of several water management policies, including water conservation, reuse, and population growth rate change was evaluated. The results show that, at present, nearly 0.53 million metric tons of CO₂ emissions per year are released due to energy use for water conveyance in distribution laterals of the Valley from Lake Mead, located 32.2 km (20 miles) southeast of the Las Vegas at an …

The 2009-2010 El Nino: Hydrologic Relief To U.S. Regions, Glenn A. Tootle, Thomas C. Piechota, Oubeidillah Aziz, William Paul Miller, Venkat Lakshmi, John A. Dracup, Carly Jerla

Civil and Environmental Engineering and Construction Faculty Research

Current forecasts by the U.S. National Oceanic and Atmospheric Administration (NOAA) are that the Pacific Ocean will experience El Niño conditions in late 2009 and into 2010. These forecasts are similar to past El Niño events in 1972–1973, 1982–1983, 1986–1987, and 2002–2003.

Evaluating the hydrologic conditions for these past El Niño events reveals that during these times, surface water supply conditions improved in many parts of the United States, including the Southeast, Midwest, and Southwest. At the same time, the Pacific Northwest and other specific regions of the United States experienced below-average water supply conditions. This is consistent with the …

Using Oceanic-Atmospheric Oscillations For Long Lead Time Streamflow Forecasting, Ajay Kalra, Sajjad Ahmad

Civil and Environmental Engineering and Construction Faculty Research

We present a data-driven model, Support Vector Machine (SVM), for long lead time streamflow forecasting using oceanic-atmospheric oscillations. The SVM is based on statistical learning theory that uses a hypothesis space of linear functions based on Kernel approach and has been used to predict a quantity forward in time on the basis of training from past data. The strength of SVM lies in minimizing the empirical classification error and maximizing the geometric margin by solving inverse problem. The SVM model is applied to three gages, i.e., Cisco, Green River, and Lees Ferry in the Upper Colorado River Basin in the …

Regional Analysis Of Trend And Step Changes Observed In Hydroclimatic Variables Around The Colorado River Basin, William Paul Miller, Thomas C. Piechota

Civil and Environmental Engineering and Construction Faculty Research

Recent research has suggested that changes in temperature and precipitation events due to climate change have had a significant impact on the availability and timing of streamflow. In this study, monthly temperature and precipitation data collected over 29 climate divisions covering the entire Colorado River basin and monthly natural flow data from 29 U.S. Geological Survey (USGS) gauge locations along the Colorado River are investigated for trend or step changes using parametric and nonparametric statistical tests. Temperature increases are persistent (at least 10 climate divisions over 6 months in trend analysis) throughout the year over the Colorado River basin, whereas …

Relationships Between Pacific And Atlantic Ocean Sea Surface Temperatures And U.S. Streamflow Variability, Glenn A. Tootle, Thomas C. Piechota

Civil and Environmental Engineering and Construction Faculty Research

An evaluation of Pacific and Atlantic Ocean sea surface temperatures (SSTs) and continental U.S. streamflow was performed to identify coupled regions of SST and continental U.S. streamflow variability. Both SSTs and streamflow displayed temporal variability when applying the singular value decomposition (SVD) statistical method. Initially, an extended temporal evaluation was performed using the entire period of record (i.e., all years from 1951 to 2002). This was followed by an interdecadal-temporal evaluation for the Pacific (Atlantic) Ocean based on the phase of the Pacific Decadal Oscillation (PDO) (Atlantic Multidecadal Oscillation (AMO)). Finally, an extended temporal evaluation was performed using detrended SST …

Coupled Oceanic-Atmospheric Variability And U.S. Streamflow, Glenn A. Tootle, Thomas C. Piechota, Ashok Singh

Civil and Environmental Engineering and Construction Faculty Research

A study of the influence of interdecadal, decadal, and interannual oceanic-atmospheric influences on streamflow in the United States is presented. Unimpaired streamflow was identified for 639 stations in the United States for the period 1951–2002. The phases (cold/negative or warm/positive) of Pacific Ocean (El Niño–Southern Oscillation (ENSO) and Pacific Decadal Oscillation (PDO)) and Atlantic Ocean (Atlantic Multidecadal Oscillation (AMO) and North Atlantic Oscillation (NAO)) oceanic-atmospheric influences were identified for the year prior to the streamflow year (i.e., long lead time). Statistical significance testing of streamflow, based on the interdecadal, decadal, and interannual oceanic-atmospheric phase (warm/positive or cold/negative), was performed by …

Soil Moisture As An Indicator Of Weather Extremes, Venkat Lakshmi, Thomas C. Piechota, Ujjwal Narayan, Chunling Tang

Civil and Environmental Engineering and Construction Faculty Research

In this paper, we investigate floods and droughts in the Upper Mississippi basin over a 50-year period (1950–1999) using a hydrological model (Variable Infiltration Capacity Model – 3 Layer). Simulations have been carried out between January 1950 and December 1999 at daily time-step and 1/8° spatial resolution for the water budget and at hourly time-step and 1° spatial resolution for the energy balance. This paper will provide valuable insights to the slow response components of the hydrological cycle and its diagnostic/predictive value in the case of floods and droughts. The paper compares the use of the Palmer Drought Severity Index …