586 research outputs found
texas-skew-update-2021
No full textA permanent copy of a data repository resulting from project 0-6977 Update Texas Skew Coefficients, including interim reports and the final report (as pdf and source)
When the data are final this sentence will be deleted</strong
Relational comparisons: the assembling of Cleveland’s waterfront plan
Full text linkThis paper uses the ongoing attempts to redevelop the Cleveland waterfront to reveal the relational comparative geographies that are present in a number of contemporary urban revalorization strategies. It draws on archival papers, semi-structured interviews, and the local grey literature to make three contributions to the existing urban-global studies literature. First, the paper argues that many contemporary waterfront and other similar redevelopment schemes are inherently comparative, with a significant amount of seemingly territorial politics and urban policy making characterized by actors’ engagements with places elsewhere. Second, it shows that the framing of urban policy through relational comparisons is an established practice in many cities and that current redevelopment plans should be understood as informed by previous rounds of relational and territorial policy making. Third, it points to the importance of consultants in the current era – as examples of actors of transference – in shaping not only redevelopment plans but also the framing of the city in relation to other cities
Hydrograph synthesis using a mechanistic transformation and survival probability model: a tool to estimate behavior on un-gaged watersheds
No full textUnit hydrographs are used to predict stream flow hydrographs from a rainfall hyetograph at the outlet of a catchment. Such synthesis requires a hydrograph kernel function and a loss model to account for the fraction of precipitation that does not appear at the outlet. Herrmann (2013) conceptualized loss as a survival probability to couple the statistical-mechanical description of temporal-spatial transformation (the unit hydrograph) with survival (the loss model) into a single approach to estimate the entire behavior with a minimal watershed description. Cleveland et al. (2008) created a particle-tracking algorithm to process digital elevation models (DTRM) and synthesized hydrographs for over 100 catchments with observed precipitation and runoff records. The results were comparable to conventional hydrograph analysis.
This research uniquely integrates Herrmann's survival probability model into the DTRM program, treating it as a Bernoulli loss process. This allows for the simultaneous generation of a hydrograph kernel and proportional loss model from a minimal description of the watershed. The performance of this approach is tested on nearly 25 catchments in Texas with 351 paired rainfall-runoff data. An analysis is carried out to determine whether the probabilities obtained from the model are related to watershed size, watershed geography, and the fraction of rainfall particles at the outlet.
The model's results allowed for the parametrizing of the unit hydrograph. The derived unit hydrograph parameters used to simulate storm events exhibited episodic behavior that closely mirrored observed patterns in runoff volume and peak discharge, although the magnitudes were not always identical in most of the simulated storm events. However, the model was more consistent in predicting the volume of the runoff, than it did peak discharge. The model's performance across the various drainage areas was consistent indicating the performance is not influence by factors such as watershed size.
Additionally, no definitive relationship between probability and watershed size was observed in the results. The relationship between probabilities and fractions of particles was not linearly related. The variability in probability and fraction of particles means there is a strong dependence
on other watershed characteristics such as main channel length, and difference in channel elevation of the watershed. Though a definitive relationship was not established between the probabilities and watershed geography, probabilities were high for all watersheds in Dallas and Houston
MANOVA modelling of a chiropractic longitudinal study using multiple imputation
Full text linkThe purpose of this report is to present the detailed statistical analysis of a randomised, placebo-controlled trial comparing two different treatment modalities to an intervention of no known benefit for people with acute or subacute thoracic spine pain.
The therapy arms consist of Spinal Manipulative Therapy (SMT) and Graston Technique (GT) and the placebo is a non-functional ultrasound. A placebo group was utilised because at present there are no proven treatments for non-specific thoracic pain. This trial is registered with the Australia and New Zealand Clinical Trials Registry. Ethics approval has been granted by Murdoch University Human Research and Ethics Committee, number 2007/274.
The aim of this three arm trial was to test the efficacy of SMT and GT as independent modalities compared to detuned ultrasound for the outcomes of pain and disability. The latter were measured using the Visual Analogue Scale (VAS) and a modified Oswestry Back Pain Disability Index. The study was conducted at the Murdoch University Chiropractic student clinic in Perth, Australia, and the protocol published in Crothers et al (2008).
In this report, Section 2 provides an initial exploratory analysis of the data, Section 3 outlines the statistical models used in the final analysis, Section 4 defines these models in mathematical terms, Section 5 discusses the management of missing values via multiple imputation and Section 6 presents the results of the statistical modelling and hypothesis tests. The clinical study will be published in full elsewhere
Stormwater drainage analysis of Marsha Sharp Freeway and University Avenue
No full textOne recent transportation infrastructure update in Lubbock, Texas, is the Marsha
Sharp Freeway (MSF) portion of the US 62/82 Highway, which will eventually extend
from Interstate 27 to 3.6 miles west of West Loop 289. The portion of the freeway that
crosses through the Texas Tech University (TTU) campus was completed in 2009, and
much of that section was constructed well below previous ground surface elevation. The
sag point of the Freeway below University Avenue flooded several times since
September 2014 during intense rainfall events, sometimes coupled with backflow through
the MSF storm inlets. The Lubbock District of the Texas Department of Transportation
(TxDOT) engaged our team to [1] review previous hydrologic and hydraulic efforts, [2]
update the current description of the local watershed and storm sewer conditions, [3]
compare the 50‐yr design event to the recent intense rainfall events, [4] confirm operation
of the pumped drainage system for the TTU football stadium, [5] assemble a hydrologic
and hydraulic model for the system, and [6] propose potential alternative solutions. We
developed a SWMM model and found that the storm sewer system performed as intended
in the original TxDOT design. The recent storm events had typical annual exceedance
probabilities of 2 to over 20 percent. In the last 20 years, development on the TTU
campus greatly increased the runoff from about 200 contributing acres, with more
significant impact than the football stadium drainage system. Several alternative
strategies were simulated to demonstrate their effects on the amount and timing of runoff
flows
Quantifying Floodwater Volumes and Defining Diversion Pathways: Data-Driven Analysis, and Mathematical Modeling Using Python
No full textIn Texas, significant spatial fluctuations in hydrometeorological behavior occur \cite{paul2018fatalities-flood}. While some areas experience a substantial increase in hydrometeorological impacts (excess runoff), other regions, such as the South Plains, encounter a notable decrease in water availability (drought). Effective water management is crucial not only for preventing and reducing vulnerability to floods in water excess regions, but also for increasing water availability in areas facing a substantial decline in water resources. This study involves a mathematical assessment of the total volume that can be diverted from a river station based on real observations. It also analyzes pipeline route profiles that could potentially be integrated to divert excess floodwater from the capturing zone to the South Plains, which is the targeted destination. An obvious approach involves collecting excess floodwater above some action stage to keep water levels below the desired level, and diverting these excess waters to the target destination. The action stage refers to the level at which the \ac{NWS} or its partners must take steps to reduce the risk of flooding when a stream is rising \cite{roland2014floodactionstage}. The maintenance of flow depth at a specific level can be achieved through various technologies such as adjustable side-weirs, also known as leaping weirs, placed on the channel's side to collect lateral flow in a detention basin when the main channel's water surface rises above the weir crest \cite{swamee1994side-weir}. This thesis addresses the complex challenges of retrieving hydrological data, developing rating curve models, computing excess floodwater volumes above critical stages, and specifically integrating the identification and evaluation of diversion paths for floodwater. The tool's applicability in diverting excess floodwater from Houston to Lubbock demonstrates its potential to optimize water distribution, not only for flood mitigation but also for alleviating water scarcity in drought-affected regions. To streamline the analysis flow process, Python-based automation programs are developed within this study. This configuration aims to ease the process of replication and workability with real-time flow data from online sources. The analysis employs a data-driven approach to study observational data using various mathematical models, including logarithmic, power law, exponential, and custom functions. Historical data ensure a better understanding of the relationship between flow rate, gauge height, and excess floodwater that can potentially be diverted, ensuring that this understanding is grounded in reality. The main contributions of this thesis include automating data collection, computation, and result generation using Python. The findings offer valuable insights into flood mitigation and river management, facilitating a more sustainable utilization of water resources. Additionally, the tool explores the probability of floodwater volume as a predictive tool for estimating the expected average floodwater and its standard deviation. Furthermore, it identifies wind farm energy points that can potentially enhance water diversion strategies. Accurate flood volume estimations and optimized water resource allocation could significantly impact local and regional flood management policies and water allocation strategies
Developing precipitation intensity-duration-frequency (IDF) models using nonlinear minimization in R
No full textDevelopment of rainfall coefficients from Intensity-Duration-Frequency (IDF) models has been used in the United States at least since the 1970s. Rainfall coefficient development methods involve regression analysis to best fit a line through an observed set of rainfall depths at varying durations and frequency. IDF equations provide an advantage to engineers who wish to calculate intensities at varying durations. IDF models are constructed based on rainfall patterns and thus vary by geographic location. The IDF model used in the state of Texas is found in the Texas Department of Transportation’s (TxDOT) Hydraulic Design Manual. The IDF model is composed of e, b and d variables known as the Texas rainfall coefficients. The most recent method for developing the e, b and d rainfall coefficients in Texas was completed through the
0-6824-1 TxDOT project that employed an ordinary least squares (OLS) regression. The OLS method required analyst time to linearize a nonlinear equation. Linearization within this thesis refers to transforming a nonlinear equation into linear form. The OLS method developed rainfall coefficients using linear regression analysis, one-dimensional optimization and a predicted residual sum of squares error (PRESS) statistic.
We decided to develop the coefficients directly through nonlinear minimization (NLM) to cut down on time and cost, and increase efficiency. In this thesis we present the background of intensity-duration-frequency models, the previous OLS method, the suggested NLM method, and a comparison of the results between the two methods in graphical and tabular form. We further discuss the adaptability, efficiency and regression fit of the two methods.
In addition, we present two R scripts, created to develop coefficients for various forms of IDF models. R is an open source, statistical programming language and software. The first code accepts data for single rainfall stations, and the second code accepts data for an entire state based on frequency. Both codes use the nlm package in R to develop the IDF model. This thesis presents the code with a general guidance but it is not meant to be a tutorial
Evaluating use of sub-grade drains with permeable friction course for stormwater drainage: Physical model studies
Full text linkWater standing on pavements is a major safety concern. Water accumulation on
roadways leads to splash and spray and even hydroplaning, which can contribute
significantly to auto accidents. This research will design and test the use of underdrains beneath permeable friction course (PFC) to eliminate standing water on roadway surfaces, especially difficult drain segments. The project includes both large-scale testing and numerical modeling of storm water drainage. The large–scale testing involves testing a few pavement sections and measuring water surface within and on the PFC. The numerical model will couple the run-off on PFC surface with the seepage within the PFC to avoid the limitations of existing numerical models. After calibration by the test data, the numerical model will be used to simulate the dynamic process of infiltration, run-off and seepage for various pavement conditions under different rainfall events. The addition of underdrains to facilitate transport of rainfall through permeable friction course reduces the distance and depth of ponding on the roadway surface. Studies, both experimental and numerical have proven the benefit of underdrains when used in conjunction with PFC to reduce ponding and standing water accumulation. A numerical model was developed in MODFLOW and calibrated to reproduce the findings of the physical model. The numerical model has shown to be applicable for a range of experimental variables (specifically changing rainfall rate and adding/removing an underdrain). The MODFLOW model does not have some of the limitations that existing models do, therefore, it is more accurate and is easy to use as well. The figures and outputs from the MODFLOW model shows that the addition of underdrains beneath PFC causes the lower flow depths within the PFC. The addition of underdrains has been shown, both in practice and in the numerical model, to increase the capacity of the PFC to transmit flow without crossing the upper boundary of the PFC layer. In practice, this reduced flow depth within the PFC layer will allow for reduced spray and splash from vehicles on the road and will reduce or eliminate the occurrence of hydroplaning, making vehicular travel more safe and secure
EBDUSA; A web-based county-level precipitation intensity-duration-frequency tool for the United States
No full textRainfall Intensity-Duration-Frequency (IDF) models have been developed at least
since the 1970s. The IDF models are appealing to design engineers because they
provide them with the ability to use a single equation to estimate rainfall intensity
at any duration. The development of IDF models involves calculating the model's
parameters by nding the best t of the model curve through an observed set of
data points of rainfall depth/intensity. There are several IDF models documented in
books and reports during years. In this research, the IDF model proposed by Texas
Department of Transportation's Hydraulic Design Manual (TxDOT{HDM) is used
to model precipitation frequency data and develop its ebd coe cients for most of the
counties in the United States. Non-linear programming techniques are used to nd
the best t of the IDF model.
This thesis presents the ebd analysis R script that constructed for IDF model devel-
opment. R is an open source, statistical programming language and software. This
code uses a non-linear minimization approach through nlm package for IDF model
development.
A web{based application named EBDUSA is designed to deploy the developed ebd
coe cients and perform the calculation of the intensity of a user-de ned duration.
This thesis documents the EBDUSA web application development process along with
its codes and scripts
Modeling inlet hydraulic performance using the storm water management model
No full textThe Texas Department of Transportation (TXDOT) uses Type – H inlets as a median drain for divided highways and as lateral drains on feeder roads. The Federal Highway Administration (FHWA) manual presents the hydraulic aspects of drop – type median inlets. These inlets are usually designed using empirical equations, that are time consuming, propagate rounding errors, and have multiple solutions.
One of the solutions for such problems is the use of a modeling program to attempt to simulate drop – type inlets. The modeling was performed using over 250 physical experiments conducted on Type – H inlets at Texas Tech University. The experiments were performed in an 8 ft wide by 48 ft long flume, with tiltable slopes of 0.5%, 1.0%, and 2.0%.
The U.S. Environmental Protection Agency (EPA) Storm Water Management Model (SWMM) was used to explore the ability of the program to simulate drop – type inlets. The methodology describes the physical models and how the drop – inlets were conceptualized and then modeled in SWMM. The results of the modeling effort found that the simulated values were within 2.0% of the observed values for the approach flow and outflow of the inlet, but could not predict depths well. SWMM can perform adequately for use in designing Type – H inlets with minimum input information, with the caveat that the depth predictions are poor. Future work should include different types of inlets to test the methodology, and refinement of the modeling technique to more accurately predict flow depths
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