Call number: LD2668 .T4 1984 S22 / Master of Science

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.

Ecosystems transition quickly in the Anthropocene, whereas biodiversity adapts more slowly. Here we simulated a shifting woodland ecosystem on the Colorado Plateau of western North America by using as its proxy over space and time the fundamental niche of the Arizona black rattlesnake (Crotalus cerberus). We found an expansive (= end-of-Pleistocene) range that contracted sharply (= present), but is blocked topographically by Grand Canyon/Colorado River as it shifts predictably northwestward under moderate climate change (= 2080). Vulnerability to contemporary wildfire was quantified from available records, with forested area reduced more than 27% over 13 years. Both 'ecosystem metrics' underscore how climate and wildfire are rapidly converting the Plateau ecosystem into novel habitat. To gauge potential effects on C. cerberus, we derived a series of relevant 'conservation metrics' (i.e. genetic variability, dispersal capacity, effective population size) by sequencing 118 individuals across 846 bp of mitochondrial (mt)DNA-ATPase8/6. We identified five significantly different clades (net sequence divergence = 2.2%) isolated by drainage/topography, with low dispersal (F-ST = 0.82) and small sizes (2N(ef) = 5.2). Our compiled metrics (i.e. small-populations, topographic-isolation, low-dispersal versus conserved-niche, vulnerable-ecosystem, dispersal barriers) underscore the susceptibility of this woodland specialist to a climate and wildfire tandem. We offer adaptive management scenarios that may counterbalance these metrics and avoid the extirpation of this and other highly specialized, relictual woodland clades.

A field study of the feasibility and the performance of a sustainable drainage technique combined with a renewable energy device to provide heating in a domestic setting was carried out from March 2008 to November 2010 to acquire practical data about the system’s operation. Among all the sustainable drainage techniques, permeable pavement system (PPS) was selected to be applied in this project since this particular technique can be used for driveways and car-parking hard standings, but more specially they can be designed as a tanked system whereby an impermeable membrane is installed at the bottom of the tank in order to hold the rainwater collected as runoff from hard areas and roofs before releasing it in a controlled manner. The renewable energy device applied in this study is a ground source heat pump system (GSHP), which has been found in previous studies to provide a better performance when installed in wet conditions. Based on this, the PPS and the GSHP with horizontal ground heat exchanger (GHE) were integrated in a 350mm deep reservoir under ‘real life’ conditins. The combined system operated in heating mode in a family–sized, three bedrooms detached EcoHouse at the Building Research Establishment Innovation Park, Watford, UK. Monitoring the combined system included taking measurements of the temperature of the conditioned space, the ground around the PPS/GSHP system, and of the ambient air every 10 minutes. Assessing the performance of the PPS/GSHP system involved investigating the effect of extracting heat via the GHE on the ground temperature, the impact of the PPS/GSHP on the thermal profile of the air above the surface of the reservoir, and computing the PPS/GSHP coefficient of performance (CoP). The thesis includes information about the design of the PPS/GSHP system including the structure of the sub-base, types and size of the used aggregate and stone, the depth of the excavated reservoir amongst others, also the technical problems that materialized, largely due to the fact that the PPS/GSHP was installed and operating under real-life circumstances. Results obtained from the study provided evidence for the workability of the combined system in regards of stormwater management and of providing heat to the EcoHouse. However, monitoring the rainwater stored in the reservoir showed that, due to leakage, the top part of the buried coil was not covered with water. The monitoring also revealed that the rainwater surrounding parts of the coil was, in severe weather, frozen. Moreover, highly significant correlations (p<0.01) were calculated for the ambient air and the ground temperature relationships with the CoP. All of these factors resulted in a 1.8 coefficient of performance being obtained. This low figure was related to the shallow depth of the reservoir since it became clear that its ground temperature was greatly influenced by the ambient air temperature. The study also revealed that the evaporation process was prevented from occurring due to the Inbitex™ composite layer, as a result there was no significant effect on cooling the thermal profile of the air near the surface of the pavement. Furthermore, it was concluded that continuous heat extraction from the ground contributed to an underground temperature drop.

published_or_final_version / Environmental Management / Master / Master of Science in Environmental Management

Accurate predictions of macroscopic multiphase flow properties, such as relative permeability and capillary pressure, are necessary for making key decisions in reservoir engineering. These properties are usually measured experimentally, but pore-scale network modeling has become an efficient alternative for understanding fundamental flow behavior and prediction of macroscopic properties. In many cases network modeling gives excellent agreement with experiment by using models physically representative of real media. Void space within a rock sample can be extracted from high resolution images and converted to a topologically equivalent network of pores and throats. Multiphase fluid transport is then modeled by imposing mass conservation at each pore and implementing the Young-Laplace equation in pore throats; the resulting pressure field and phase distributions are used to extract macroscopic properties. Advancements continue to be made in making network modeling predictive, but one limitation is that artificial (e.g. constant pressure gradient) boundary conditions are usually assumed; they do not reflect the local saturations and pressure distributions that are affected by flow and transport in the surrounding media. In this work we demonstrate that flow behavior at the pore scale, and therefore macroscopic properties, is directly affected by the boundary conditions. Pore-scale drainage is modeled here by direct coupling to other pore-scale models so that the boundary conditions reflect flow behavior in the surrounding media. Saturation couples are used as the mathematical tool to ensure continuity of saturations between adjacent models. Network simulations obtained using the accurate, coupled boundary conditions are compared to traditional approach and the resulting macroscopic petrophysical properties are shown to be largely dependent upon the specified boundary conditions. The predictive ability of network simulations is improved using the novel network coupling scheme. Our results give important insight into upscaling as well as approaches for including pore-scale models directly into reservoir simulators. / text

<p>Övergödning utgör ett av de allvarligaste hoten mot Östersjöns miljö. Storleken av näringsbelastningen till havet behöver därför bestämmas med hjälp av tillgängliga matematiska modeller. Modellen ”Generalised Watershed Loading Functions” (GWLF), en ickedistribuerad parametermodell som uppskattar hydrologi och månatlig näringsbelastning, tillämpades på avrinningsområdet till Daugava som mynnar i Östersjön. Syftet med studien var att genom modellering av historisk transport av näringsämnen till Östersjön ta fram parametrar och indata som sedan kan användas vid applicering av GWLF på omkringliggande avrinningsområden. Data från 1990-talet användes för kalibrering av modellen och data från 1980-talet för validering. Årlig kvävebelastning modellerades med R2värdet 0,78 för kalibreringsperioden. Modellerad årlig kvävebelastning för valideringsperioden underskattades med ungefär 30 % vilket troligen beror på att kvävekoncentrationer i grundvatten och ytavrinning minskade mellan 1980- och 1990-talen.</p><p>Fosforbelastningen underskattades jämfört med rapporterade värden vilket troligen beror på att enskilda avlopp inte inkluderades och att rapporterade punktutsläpp är för låga.</p><p>Modifikationer av modellen föreslås för prediktion av näringsbelastningar under lång tid och behovet av harmoniserad, uppdaterad och lättillgänglig data för näringstransportsmodellering diskuteras.</p> / <p>Eutrophication is one of the most serious threats to the Baltic Sea environment. Nutrient loading into the sea therefore needs to be quantified by available mathematical models. The Generalised Watershed Loading Functions (GWLF), a lumpedparameter model that predicts hydrology and monthly nutrient loads, was applied to the Daugava River Basin, discharging into the Baltic Sea. The aim of the study was to model historic transport of nutrients into the Baltic Sea and thereby produce estimates of parameters and input data needed for a spatial extension of the GWLF to surrounding river basins.</p><p>Calibration data were taken from the 1990’s and validation data from the 1980’s. Yearly nitrogen loads were modelled with an R2 value of 0.78 for the calibration period. Predicted yearly nitrogen loads for the validation period were about 30 % lower than reported values, probably depending on decreasing groundwater and runoff concentrations between the 1980’s and 1990’s. Phosphorus loads were underestimated compared to reported values, the main reason probably being the exclusion of septic systems and too low reported point sources.</p><p>Modifications of the model are suggested for longterm predictions of nutrient loads and the need for harmonised, uptodate and generally accessible data for nutrient transport modelling discussed.</p>

Peatlands cover approximately 2-3% of the world’s land area yet represent approximately a third of the worlds estimated total soil carbon pool. They therefore play an important role in regulating global atmospheric CO2 and CH4 concentrations, and even minor changes in their ability to store carbon could potentially have significant effects on global climate change. Much previous research has focussed primarily on land-atmosphere fluxes. Where aquatic fluxes have been considered, they are often in isolation from the rest of the catchment and usually focus on downstream losses, ignoring evasion (degassing) from the water surface. However, as peatland streams have been repeatedly shown to be highly supersaturated in both CO2 and CH4 with respect to the atmosphere, they potentially represent an important pathway for catchment GHG losses. This study aimed to a) create a complete GHG and carbon budget for Auchencorth Moss catchment, Scotland, linking both terrestrial and aquatic fluxes, and b) understand what controls and drives individual fluxes within this budget. This understanding was further developed by a short study of C exchange at the peat-aquatic interface at Mer Bleue peatland, Canada. Significant variability in soil-atmosphere fluxes of both CH4 and N2O emissions was evident at Auchencorth Moss; coefficients of variation across 21 field chambers were 300% and 410% for CH4 and N2O, respectively. Both in situ chamber measurements and a separate mesocosm study illustrated the importance of vegetation in controlling CH4 emissions. In contrast to many previous studies, CH4 emissions were lower and uptake greater where aerenchymous vegetation was present. Water table depth was also an important driver of variability in CH4 emissions, although the effect was only evident during either periods of extreme drawdown or when the water table was consistently near or above the peat surface. Significant pulses in both CH4 and N2O emissions were observed in response to fluctuations in water table depth. Despite the variability in CH4 and N2O emissions and the uncertainty in up-scaled estimates, their contribution to the total GHG and carbon budgets was minor. Concentrations of dissolved CO2 in peatland drainage waters ranged from a mean of 2.88 ± 0.09 mg C L-1 in the Black Burn, Scotland, to a mean of 7.64 ± 0.80 mg C L-1 in water draining Mer Bleue, Canada. Using non-dispersive infra-red (NDIR) CO2 sensors with a 10-minute measurement frequency, significant temporal variability was observed in aquatic CO2 concentrations at the 2 contrasting field sites. However, the drivers of this variability differed significantly. At Mer Bleue, Canada, biological activity in the water column led to clear diurnal cycles, whereas in the Black Burn draining Auchencorth Moss, dilution due to discharge was the primary driver. The NDIR sensor data also showed differences in soil-stream connectivity both between the sites (connectivity was weak at Mer Bleue) and across the range of conditions measured at Auchencorth Moss i.e. connectivity increased during periods of stormflow. Compiling the results from both the terrestrial and aquatic systems at Auchencorth Moss indicated that the catchment was functioning as a net sink for GHGs (382 kg CO2-eq ha-1 yr-1) and a net source of carbon (143 kg C ha-1 yr-1). The greatest flux of GHGs was via net ecosystem exchange (NEE). Terrestrial emissions of CH4 and N2O combined returned only ~5% of CO2-equivalents captured by NEE to the atmosphere, whereas evasion of CO2, CH4 and N2O from the stream surface returned ~40%. The budgets clearly show the importance of aquatic fluxes at Auchencorth Moss and highlight the potential for significant error in source/sink strength calculations if they are omitted. Furthermore, the process based understanding of soil-stream connectivity suggests the aquatic flux pathway may play an increasingly important role in the source-sink function of peatlands under future management and climate change scenarios.

Storm sewer systems play a very important role in urban areas. The design of a storm sewer system should be based on an appropriate level of preventing flooding. This thesis focuses on issues relevant to decision-making in storm sewer network design considering flood risk. Uncertainty analysis is often required in an integrated approach to a comprehensive assessment of flood risk. The first part of this thesis discusses the understanding and representation of uncertainty in general setting. It also develops methods for propagating uncertainty through a model under different situations when uncertainties are represented by various mathematical languages. The decision-making process for storm sewer network design considering flood risk is explored in this thesis. The pipe sizes and slopes of the network are determined for the design. Due to the uncertain character of the flood risk, the decision made is not unique but depends on the decision maker’s attitude towards risk. A flood risk based storm sewer network design method incorporating a multiple-objective optimization and a “choice” process is developed with different design criteria. The storm sewer network design considering flood risk can also be formed as a single-objective optimization provided that the decision criterion is given a priori. A framework for this approach with a single objective optimization is developed. The GA is adapted as the optimizer. The flood risk is evaluated with different methods either under several design storms or using sampling method. A method for generating samples represented by correlated variables is introduced. It is adapted from a literature method providing that the marginal distributions of variables as well as the correlations between them are known. The group method is developed aiming to facilitate the generation of correlated samples of large sizes. The method is successfully applied to the generation of rainfall event samples and the samples are used for storm sewer network design where the flood risk is evaluated with rainfall event samples.

L'hydrocéphalie est un trouble de l'hydrodynamique du liquide cérébro-spinal (LCS) responsable d'une augmentation de volume du compartiment imparti à ce liquide. Nous présentons l'état actuel des connaissances concernant le LCS et sa dynamique (sécrétion, circulation, réabsorption), l'hydrocéphalie et son traitement. Nous abordons également la pression intracrânienne (PIC), indissociable des éléments précédents. Ce travail se compose d'une recherche bibliographique, d'une recherche clinique et d'une recherche fondamentale en laboratoire. Le but de l'étude clinique est de mesurer le débit externalisé de LCS (Q'extcsf) et la PIC chez le patient hydrocéphale porteur d'une dérivation ventriculaire externe (DVE). Douze patients sont inclus. Les moyennes (+/- DS) de Q'extcsf et de la PIC sont respectivement 7.5 +/- 3.4 ml/h et 12.4 +/- 2.7 mmHg. Deux profils de Q'extcsf sont identifiés : un profil de sécrétion continu et un profil de sécrétion discontinu. Les variations à court terme de Q'extcsf et de la PIC ne sont généralement pas reliées, probablement en raison des relations pression/volume à l'intérieur du compartiment intracrânien. Q'extcsf est plus faible que le débit de sécrétion de LCS (21 ml/h), laissant supposer une absorption persistante ou une sécrétion diminuée. Le but de la recherche en laboratoire est de comparer les relations pression/résistance en fonction du débit de deux systèmes de DVE. L'un des systèmes commercialisé présente, pour les bas débits, une résistance très importante, qui décroît quand le débit augmente, pour se stabiliser à 0.05 hPa/ml/h à partir de 20 ml/h. L'autre système présente une résistance pratiquement nulle quel que soit le débit. / Hydrocephalus is a hydrodynamic disorder of cerebrospinal fluid (CSF) responsible for an increasing volume of its dedicated compartment. We present the current knowledge regarding CSF and its dynamic (secretion, circulation and absorption), hydrocephalus and its treatment. In addition, we study intracranial pressure (ICP), a variable indissociable from the previous ones. In addition to this bibliographic research, this work is composed of a clinical research and a fundamental research. The aim of the clinical study is to monitor externalized CSF outflow (Q'extcsf) and ICP in hydrocephalic patients with external ventricular drainage. Twelve patients are included. The mean + SD Q'extcsf and ICP are respectively 7.5 + 3.4 ml/h and 12.4 + 2.7 mmHg. Two patterns of Q'extcsf are identified: a continuous profile and a discontinuous one. The short term variations of Q'extcsf and ICP are usually unrelated, presumably because of the pressure/volume relationships within the intracranial compartment. Q'extcsf is lower than the reference production rate (21 ml/h), raising the question of persistent CSF absorption and/or depressed secretion. The aim of the fundamental research is to compare the pressure/resistance relationships to flow of two external ventricular drainage sets. One of the two existing systems present, for lower outflow, a very important resistance, decreasing with flow increase, and stabilizing at 0.05 hPa/ml/h when flow reaches 20 ml/h. the other system shows an almost nil resistance whatever the flow.