331 |
The effects of rainfall runoff from urban and rural watersheds on trihalomethane precursors in streamsOwen, Polly C. 30 June 2009 (has links)
The purpose of this research was to investigate the relationship between watershed land use and seasonal changes on THM-formation potential from the waters of four streams located in northern Virginia. Specific objectives were to observe the effect of impoundment on downstream THM precursor concentrations and to evaluate the molecular-size distributions of THM-precursors in stream waters as to the influence of seasonal changes, storm events, and watershed land use.
Raw water samples were collected from October 1989 through May 1990 during baseflow and storm conditions. The samples were fractionated through 500, 1000, 5000, 10000, and 30000 dalton ultrafilters and were then chlorinated to determine the THM-formation potential based on the total organic concentration of the water fraction.
From the data collected, it was shown that seasonal changes influenced the TOC and THM-precursor loadings in runoff from the watersheds. Fall runoff from Broad Run contributed the highest mass loading. Impoundment was seen to increase the amount of THM precursors downstream of Lake Manassas on Broad Run with the largest difference observed during the fall event. The more-rural watersheds draining into Broad Run contributed the most TOC and THM precursors during the fall runoff event, while the more-urban watersheds (Bull Run and Holmes Run) contributed more TOC and THM precursors in the winter and spring runoff. / Master of Science
|
332 |
The Study of Temporal and Spatial Variability of Degree Day Factor of Snowmelt in ColoradoPokhrel, Pranav 05 1900 (has links)
Snowmelt is one of the major sources of surface water supply and ground-water recharge in high elevation areas and can also cause flooding in snow dominated watersheds. Direct estimation of daily snowmelt requires daily snow water equivalent (SWE) measurements that are not always available, especially in places without monitoring stations. There are two alternative approaches to modeling snowmelt without using direct measurements of SWE, temperature-based and energy-based models. Due to its simplicity, computational efficiency, and less input data requirement, the temperature-based method is commonly used than the energy-based method. In the temperature-index approach snowmelt is estimated as a linear function of average air temperature, and the slope of the linear function is called the degree-day factor (DDF). Hence, the DDF is an essential parameter for utilizing the temperature-based method to estimate snowmelt. Thereby, to analyze the spatial properties of DDF, 10 years DDF from the entire state of Colorado was calculated for this research. Likewise, to study the temporal properties, DDFs for 27 years from the White Yampa water basin and the Colorado Headwaters water basin were calculated.
As a part of the spatial analysis, the calculated DDFs were correlated with spatial variables (slope, aspect, latitude and elevation) and a spatial correlation graph was created to observe the possibility of predicting DDF. Also a multivariate regression model was prepared using these spatial variables to predict the DDF using spatial variables. Further, the DDFs calculated from Colorado headwaters and the White Yampa water basins were correlated for annual temporal variation, daily variation, variation with peak snow water equivalent and variation with important temporal cycles like accumulation period and melting period of snowmelt. The result obtained from this study showed that the variability of DDF is more dependent upon temporal factors compared to the spatial factors. Also, the results showed that predicting DDF is a difficult process and requires complex methods than simple linear models or multivariate models.
|
333 |
Hydrologické simulace odtoků vody z povodí při srážko-odtokových událostech / Event-based rainfall-runoff modelling of the selected river basinTICHÁČEK, Pavel January 2018 (has links)
This thesis deals with the event-based rainfall-runoff modelling of the selected river basin. This thesis is based on my previous work "Factors affecting the water discharge from the river basin during rainfall-runoff events". In that work I described factors, which have effect on water runoff from the river basin. This thesis was solved on basin of Jílecký stream. Water runoff from basin is affected with a number of factors, the most significant are slope of the terrain, soil saturation, geological and pedological conditions, vegetation cover and anthropogenic influence. Calculations of direct runoff were realised with method of CN curves, with using BPEJ map, land use map gained from Corine Land Cover 2006 and maximum daily precipitation sums with 2, 10, 20, 50 and 100 years probabilities recurrence obtained from the rainfall station Netřebice. Calculations were performed in a numerical method using vector data and a raster method performed in ArcMap. In the next step I performed simulations of various scenarios of change in river basic characteristics such as soil saturation change, grassing of arable land with a slope greater than 12°, grassing of all arable land and enlargement the built-up area in the river basin.
|
334 |
Srážko-odtokový proces v podmínkách klimatické změny / Rainfall runoff process in time of climate changeBenáčková, Kateřina January 2018 (has links)
The aim of The Diploma Thesis was to compile a conceptual rainfall-runoff model, that would be eligible to model discharge in conditions of climate changes. After thorough verifications of possible variants, user program Runoff Prophet that is eligible to simulate discharge in closing profile of any river basin was compiled within this paper. Runoff Prophet is deterministic lumped model with monthly computation time step and from the hydrologic phenomena it takes soil moisture, evapotranspiration, groundwater flow and the watercourse flow into account. Its calibration is based on the differential evolution principle with Nash–Sutcliffe model efficiency coefficient as the calibration criterion. Developed software was tested on Vír I. catchment basin and the results of this probe were evaluated from viewpoints of air temperature, precipitation and discharge characteristics in the Dalečín measurement river cross section in distant future according to A1B SRES climate scenario, implemented in LARS-WG weather generator.
|
335 |
Characterization of runoff from land disposal of beef cattle feedlot wastes with a comparison of two sampling methodsBrandenburg, Barton Lewis January 2011 (has links)
Digitized by Kansas Correctional Industries
|
336 |
Calibration of a rainfall simulator for determination of soil conservation service runoff curve numbersLaForce, Russell Wayne January 2011 (has links)
Typescript (photocopy). / Digitized by Kansas Correctional Industries
|
337 |
The effect of beef feedlot runoff on some soil chemical properties and ground water qualityTerry, Roger Van. January 1979 (has links)
Call number: LD2668 .T4 1979 T47 / Master of Science
|
338 |
Effectiveness of Biochar Addition in Reducing Concentrations of Selected Nutrients and Bacteria in RunoffWilliams, Rachel 01 January 2016 (has links)
Land application and storage of horse manure and municipal sludge can increase nutrient and bacteria concentrations in runoff. Biochar increases soil nutrient retention when used as a soil amendment. The objectives of this study were to determine if biochar, when mixed with horse manure or sludge, affects runoff concentrations of total Kjehldahl nitrogen (TKN), ammonia-nitrogen (NH3-N), nitrate (NO3-N), total phosphorus (TP), dissolved phosphorus (DP), total suspended solids (TSS), chemical oxygen demand (COD), and fecal coliforms (FC). Horse manure and sludge were applied to 2.4 x 6.1 m fescue plots (six each), with three plots of each material amended with 5-8% biochar w/w. Simulated rainfall (101.6 mm/h) was applied to the 12 treatment plots and three control plots. The first 0.5 h of runoff was collected and analyzed for the above-listed parameters. The data were analyzed using an ANCOVA, with SCS runoff curve number (CN) used as the covariate. In general, CN was directly correlated to runoff concentrations of parameters. Plots with low CN values displayed no treatment differences for any measured parameter. Biochar reduced runoff concentrations of TKN and NH3-N for municipal sludge treatments, and TKN, NH3-N, TP, TSS, and FC for horse manure treatments.
|
339 |
Rainfall and Runoff in the Upper Santa Cruz River Drainage BasinSchwalen, Harold C. 01 September 1942 (has links)
This item was digitized as part of the Million Books Project led by Carnegie Mellon University and supported by grants from the National Science Foundation (NSF). Cornell University coordinated the participation of land-grant and agricultural libraries in providing historical agricultural information for the digitization project; the University of Arizona Libraries, the College of Agriculture and Life Sciences, and the Office of Arid Lands Studies collaborated in the selection and provision of material for the digitization project.
|
340 |
Complex, deterministic hydrological modelling towards decision support for urban catchment managementMales, Ryan James 12 1900 (has links)
Thesis (M.ScEng.)--Stellenbosch University, 2001. / ENGLISH ABSTRACT: Historically, urban waterresources have too often been managed without recognition that the
flow in a river integrates many landscape and biological features. This has often resulted in
the elimination of natural processes and their replacement by man-made streamlined
structures with the effects of increased urbanisation being primarily addressed from an
engineering and economics point of view to the detriment of environmental and social issues.
Catchment Management, as legislated in the Water Act, No. 36 of 1998, is a management
approach to address the negative consequences of an urban stormwater design philosophy
restricted to flood restriction. It is a systems approach that integrates engineering and
scientific skills, socio-economic concerns, and environmental constraints within a new multidisciplinary
decision-making process that recognises the different components of the
hydrological and aquatic cycles are linked, and each component is affected by changes in
every other component.
In order to make effective management decisions, catchment managers require tools to
provide reliable information about the performance of alternative arrangements of stormwater
management facilities and to quantify the effects of possible management decisions on the
water environment. A deterministic hydrological model is such a tool, which provides the
link between the conceptual understanding of the physical catchment characteristics and the
empirical quantification of the hydrological, water quality and ecological response.
In order to provide effective computer based decision support, the hydrological model must
be part of an integrated software application in which a collection of data manipulation,
analysis, modelling and interpretation tools, including GIS, can be efficiently used together to
manage a large potion of the overall decision process. This decision support system must
have a simple and intuitive user interface able to produce easily interpreted output. It must
have powerful graphical presentation capabilities promoting effective communication and be
designed to solve ill-structured problems by flexibly combining statistical analysis, models
and data.
The Great Lotus River canal, situated on the Cape Flats, Cape Town, has been designed and
controlled through extensive canalisation and the construction of detention pond facilities to
avoid the flooding of urban areas of the catchment. This approach has resulted in these
channels becoming stormwater drains, transporting waste and nutrients in dissolved and
particulate forms, and reducing their assimilatory capacity for water quality improvement.
In order to investigate the use of hydrological modelling in decision support for Catchment
Management, the semi-distributed, physically based model, SWMM, was applied to the Great
Lotus River canal. SWMM consists of a number of independent modules allowing the
hydrological and hydraulic simulations of urban catchments and their conveyance networks
on an event or continuous basis.
In order to ease the application of the Fortran based SWMM model, the GUl, PCSWMM98,
was developed by Computational Hydraulics Inc (CH!). This provides decision support for
SWMM through large array of tools for file management, data file creation, output
visualisation and interpretation, model calibration and error analysis and storm dynamic
analysis thus easing any simulations with SWMM. In addition, PCSWMM was developed
with a GIS functionality for graphically creating, editing and/or querying SWMM model
entities and attributes, displaying these SWMM layers with background layers and dynamic
model results, and exporting data to SWMM input files thus providing an interface between a
GIS and SWMM.
In terms of Catchment Management, the above DSS can be used effectively to assist decisionmaking.
This is to address tensions between the fundamental catchment management
considerations of physical development, social considerations and maintaining ecological
sustainability. It is at the stages of Assessment and Planning that the model can play the most
significant role in providing decision support to the Catchment Management process.
Assessment in the Catchment Management process refers to the collection, storage, modelling
and interpretation of catchment information. It is in this quantification, interpretation and
assessment of catchment information that a hydrological model contributes to an increase in
knowledge in the Catchment Management process. In identifying and quantifying, at a
sufficient temporal and spatial scale, the dominant cause and effect relationships in the urban
physical environment, a hydrological model is able to highlight the main contributing factors
to an issue. This is used in the Planning stage of the Catchment Management process and
when combining these contributing factors with assessments of the socio-economic and
administrative environments, enables the prioritisation of the principal issues requiring
attention in a Catchment Management Strategy.
It is possible to link the multiple decision-making requirements of Catchment Management
with the abilities of a hydrological model to provide information on these requirements in a
conceptual framework. This framework consists of the fundamental catchment considerations
of Physical Development, Environmental Management and Social Development and resolves
these considerations into the various management issues associated with each consideration ~s
well as its management solution. The management solutions are linked to the model through
formulating the solution in terms of the model parameters and perturbing the affected
parameters in ways to simulate the management solution. This results in model output and
graphical interpretation of the effects of the suggested management solution. A comparison
between the simulated effects of each management solution allows the Catchment
Management body to identify optimal management solutions for the various management
Issues.
The present model of the Great Lotus River catchment is sufficient to simulate the overland
and subsurface flows from individual parts of the catchment and to route these flows and
associated pollutant loadings to the catchment outlet. At its present level of complexity, the
finely discretised model subcatchment and conveyance network provides decision support for
Catchment Management through the simulation, at a pre-feasibility stage, of various
Catchment Management issues and their proposed solutions.
Given more detailed canal and drainage network dimensions and water quality data, it is
possible for the model to incorporate hydraulic calculation routines to assess the implications
of alternative river rehabilitation techniques and waste management strategies. This would
allow greater capability in assessing the role of the various BMPs in ameliorating stormwater
impacts and pollutant loading. In addition, a detailed level survey of the stormwater pipe and
canal network could result in hydrological modelling being utilised to identify critical areas
where stormwater upgrading would be necessary.
In order to facilitate future complex, finely discretised catchment hydrological models, it is
imperative that complete and detailed drainage patterns and stormwater network
characteristics are available. In addition, to minimise model generation costs and time of
model setup, this spatially representative data must be captured in a GIS for rapid inclusion
into the model. Furthermore, complete spatially representative precipitation datasets are
necessary to ensure that model error is reduced. These two issues of available spatial data and
comprehensive precipitation records are crucial for the generated models to function as
effective decision support systems for Catchment Management. / AFRIKAANSE OPSOMMING: Histories is stedelike waterbronne te dikwels bestuur sonder inagneming dat die vloei van die
rivier baie landskap- en biologiese kenmerke insluit. Dit het dikwels daartoe gelei dat
natuurlike prosesse uitgeskakel is en vervang is deur mensgemaakte, stroombelynde strukture
waarvan die effek van toenemende verstedeliking hoofsaaklik aangespreek word vanuit 'n
ingenieurs- en ekonomiese oogpunt tot nadeel van omgewings- en sosiale kwessies.
Opvangsgebiedsbestuur, soos bepaal deur die Waterwet, Wet 36 van 1998, is 'n
bestuursbenadering om die negatiewe gevolge van 'n stedelike stormwaterontwerpfilosofie
wat beperk is tot vloedbeperking aan te spreek. Dit is 'n stelselbenadering wat ingenieurs- en
wetenskaplike vaardighede, sosio-ekonomiese probleme en omgewingsbeperkings integreer
in 'n nuwe multidissiplinêre besluitnemingsproses wat erkenning daaraan gee dat die
verskillende komponente van die hidrologiese en watersiklusse verbind is, en elke komponent
beïnvloed word deur veranderings in elke ander komponent.
Om doeltreffende bestuursbesluite te neem, benodig opvangsgebiedsbestuur die hulpmiddels
om betroubare inligting oor die prestasie van alternatiewe moontlikhede VIr
stormwaterbestuurfasiliteite en om die effek van moontlike bestuursbesluite op die
wateromgewing te kwantifiseer. 'n Deterministiese hidrologiese model is so 'n hulpmiddel
wat die skakel daarstel tussen die konseptueie begrip van die fisiese opvangsgebiedskenmerke
en die empiriese kwantifisering van die water-, waterkwaliteit- en ekologiese reaksie.
Om doeltreffende rekenaarbesluitnemingsteun te verskaf, moet die hidrologiese model deel
wees van 'n geïntegreerde sagteware-aanwending waarin 'n versameling datamanipulasie-,
analise-, modellerings- en interpreteringshulpmiddels, insluitend GIS, doeltreffend saam
gebruik kan word om 'n groot deel van die algehele besluitnemingsproses te bestuur. Hierdie
besluitnemingsteunstelsel moet 'n eenvoudige en intuïtiewe gebruikersvlak hê wat in staat is
om maklik interpreteerbare uitsette te lewer. Dit moet goeie grafiese voorleggingsvermoëns
hê wat doeltreffende kommunikasie vergemaklik en ontwerp wees om swak gestruktureerde
probleme deur die buigsame samevoeging van statistiese analise, modelle en data op te los.
Die Groot Lotusrivierkanaal op die Kaapse Vlakte, Kaapstad is ontwerp en word beheer deur
uitgebreide kanalisasie en die konstruksie van detensiedamfasiliteite om die oorstroming van
stedelike opvangsgebiede te vermy. Hierdie benadering het daartoe gelei dat hierdie kanale
stormwaterafvoerpype geword het wat afval en nutriënte in opgelosde en partikelvorm
vervoer en hulle assimilasievermoë vir die verbetering van waterkwaliteit verminder.
Om die gebruik van hidrologiese modelle in besluitnemingsteun vir Opvangsgebiedsbestuur
te ondersoek, is die semi-verspreide, fisiesgebaseerde model, SWMM, op die Groot
Lotusrivierkanaal toegepas. SWMM bestaan uit 'n aantalonafhanklike modules wat die
hidrologiese en hidroulika simulasies van stedelike opvangsgebiede en hulle vervoemetwerke
per geleentheid of deurlopend monitor.
Om die aanwending van die Fortran gebaseerde SWMM model te vergemaklik is die GUl,
PCSWMM98 deur Computational Hydraulics Inc (CHD ontwikkel. Dit verskaf
besluitnemingsteun vir SWMM deur 'n groot aantal hulpmiddels vir lêerbestuur, die skep van
datalêers, uitsetvisualisering en interpretasie, modelkalibrasie, foutanalise en stormdinamikaanalise
om enige simulasies met SWMM te vergemaklik. Daarby is PCSWMM ontwikkel met
'n GIS funksionaliteit vir die grafiese daarstelling, redigering en/of navraagfunksie van
SWMM model entiteite en kenmerke, wat hierdie SWMM vlakke met agtergrondvlakke en
dinamiese modelresultate vertoon en data in SWMM inset1êers plaas en op daardie manier 'n
koppelvlak tussen 'n GIS en SWMM verskaf.
Volgens Opvangsgebiedsbestuur kan bogenoemde DSS doeltreffend gebruik word in
besluitneming. Dit IS om die spanning tussen fundamentele
opvangsgebiedsbestuursoorwegings van fisiese ontwikkeling, sosiale oorwegings en
ekologiese volhoubaarheid aan te spreek. Dis in die stadiums van Waardebepaling en
Beplanning wat die model die belangrikste rol kan vervul in die verskaffing van
besluitnemingsteun vir die Opvangsgebiedsbestuursproses.
Waardebepaling in die Opvangsgebiedbestuursproses verwys na die versameling, berging,
modellering en interpretasie van opvangsgebiedsinligting. Deur hierdie kwantifisering,
interpretasie en waardebepaling van opvangsgebiedsinligting dra 'n hidrologiese model by tot
'n verhoging in kennis in die Opvangsgebiedsbestuur. Deur die identifisering en
kwantifisering, op 'n ruim genoeg tydelike en ruimtelike skaal, van die dominante oorsaak en
gevolg verhoudings in die stedelike fisiese omgewing, kan die hidrologiese model die hoof
bydraende faktore uitlig. Dit word gebruik in die Beplanningsfase van die
Opvangsgebiedproses en wanneer hierdie bydraende faktore by die waardebepaling van die
sosio-ekonomiese en administratiewe omgewings saamgevoeg word, maak dit moontlik om
die belangrike kwessies wat aandag behoort te kry in 'n Opvangsgebiedsbestuurstrategie in
volgorde van voorrang te plaas.
Dit is moontlik om die verskeidenheid besluitnemingsvereistes van Opvangsgebiedsbestuur
met die vermoëns van 'n hidrologiese model te koppel om inligting oor hierdie vereistes in 'n
konseptuele raamwerk te verskaf. Die raamwerk bestaan uit die fundamentele
opvangsgebiedsoorwegings van Fisiese Ontwikkeling, Omgewingsbestuur en Sosiale
Ontwikkeling en los hierdie oorwegings op in die verskillende bestuursaangeleenthede wat
met elke oorweging en die bestuuroplossing geassosieer word. Die bestuursoplossings word
aan die model gekoppel deur die formulering van die oplossing volgens die modelparameters
en versteuring van die relevante parameters op sekere manier om die bestuursoplossing te
simuleer. Dit lei tot modeluitset en grafiese interpretasie van die effek van die voorgestelde
bestuursoplossing. 'n Vergelyking tussen die gesimuleerde effek van elke bestuursoplossing
laat die Opvangsgebiedsbestuursliggaam toe om die optimale bestuursoplossings vir die
verskeie bestuursaangeleenthede te identifiseer.
Die huidige model van die Groot Lotusrivieropvang is genoegsaam om die bo- en
ondergrondse vloei vanaf individuele dele van die opvangsgebied te simuleer en om die
watervloei en geassosieerde besoedelstofladings na die opvangsgebiedsuitlaatplek te lei. Op
sy huidige vlak van kompleksiteit verskaf die fyn gediskretiseerde model subopvangsgebied
en vervoernetwerk besluitnemingsteun aan Opvangsgebiedsbestuur deur die simulasie, teen 'n
voor-lewensvatbaarheidstudie, van verskeie opvangsgebiedsbestuurkwessies en die
voorgestelde oplossings.
Indien meer gedetailleerde kanaal- en dreineringsnetwerkdimensies- en waterkwaliteitdata
ingevoer word, is dit moontlik vir die model om hidroulikaberekeningsroetines te inkorporeer
om die implikasies van alternatiewe rivierrehabilitasietegnieke en afvalbestuurstrategieë te
beoordeel. Dit sou die vermoë verbeter om die waarde van die verskeie BMPs te bepaal om
die impak van stormwater en besoedelstoflading te versag. Daarby kan 'n gedetailleerde
vlakopname van die stormwaterpyp en -kanaalnetwerk daartoe lei dat hidrologiese modelle
gebruik kan word om kritieke areas te identifiseer waar stormwateropgradering nodig is.
Om toekomstige komplekse, gediskretiseerde opvangsgebiedshidrologiese modelle te
verbeter, is dit noodsaaklik dat volledige en gedetailleerde dreineringspatrone en
stormwaternetwerkkenmerke beskikbaar is. Om die model-ontwikkelingskoste en tyd bestee
aan die opstel van 'n model te minimiseer, moet hierdie ruimtelik verteenwoordigende data
ingelees word in 'n GIS vir vinnige insluiting in die model. Daarbenewens is volledige,
ruimtelik verteenwoordigende presipitasie datastelle nodig om te verseker dat modelfoute
verminder word. Hierdie twee kwessies van beskikbare ruimtelike data en omvattende
presipitasierekords is van die uiterste belang sodat die gegenereerde modelle as doeltreffende
besluitnemingsteun vir Opvangsgebiedsbestuur kan funksioneer.
|
Page generated in 0.0259 seconds