6 pp. / Water use, critical soil water depletion, and irrigation scheduling for wheat and barley are explained in this publication.

Revised; Originally Published: 2005 / 3 pp.

Revised; Originally Published: 2005 / 3 pp.

Anthropogenic climate change is arguably the greatest challenge of modern times posing significant risks to natural resources and the environment. Socio-economic change, severe droughts, and environmental concerns focus attention upon sustainability of water supplies and the ability of water utilities to meet competing demands worldwide. The 2012 Climate Change Risk Assessment identified water security as one of the most significant climate threats facing the UK. It is now recognised that household water demand management could offer a low regret adaptation measure (both financially and environmentally) given large uncertainties about future climate and non-climatic pressures. This thesis uses Anglian Water Services (AWS) Golden 100 dataset to explore the climate sensitivity of historic micro-component water-use. This work contributes to a larger integrated assessment of the South-East England water system under the EPSRC Adaptation and Resilience to a Changing Climate Coordination Network (ARCC CN). The Golden 100 is a metered record of 100 households daily water consumption by basin, bath, dishwasher, external, kitchen sink, shower, WC and washing machine use. The archive also includes socio-economic information for each household, dates of the year and daily time series of observed minimum temperature, maximum temperature, sunshine hours, soil moisture deficit, concurrent, and antecedent rainfall amounts. The methodology developed within this research provides a portable approach to error trapping, formatting and mining large, complex water sector datasets, for exploring the relative sensitivities of micro-component metered water-use to weather/non-weather variables. This research recognises both the importance of the choice to use a micro-component and the volume used. As such, logistic and linear generalised regression techniques are employed to explore the relative sensitivity of these two aspects of water-use to climatic and non-climatic variables. The 2009 UK Climate Projections (UKCP09) projections and climate analogues are then used to bound a climate sensitivity analysis of the most weather-sensitive micro-components using temperature and rainfall scenarios for the 2050s and 2080s. This research provides empirical evidence that the most weather sensitive micro-components are external and shower water-use. A key contribution of this research to existing knowledge is the non-linear response of likelihood and volume of external water-use to average air temperatures. There is an abrupt increase in the likelihood of external water-use on days above ~15??C. Climate sensitivity analysis further suggests that by the 2080s, under a hotter/drier climate, average unmetered households could be 8% more likely to use external-water and expend ~9 litres more per day during the summer. For the same parameters, high water users (defined here as the 90th percentile) could consume ~13 litres more external water per day. Importantly, this research has re-affirmed the relative importance of behavioural drivers of water-use as manifested by pronounced day of week and bank holiday signatures in both the likelihood and volume of use statistics. As such, this prompts future studies and water management efforts to consider the impact of behavioural drivers as well as climate. It must be recognised that the small sample size of the Golden 100 combined with the Hawthorn effect, self-selection and sample biases in factors such as socio-economic status, billing method and occupancy rate all limit the sample representativeness of the wider population. As such, any predictions based on the data must be treated as illustrative rather than definitive. Furthermore, the results are probably specific to the demographic and socio-economic groups comprising the sample. Nonetheless, this research sheds new light into water-use within the home thereby adding value to a dataset that was not originally collected with household-level, weather-related research in mind.

Dans le contexte du changement climatique global, il apparaît essentiel de prendre en compte l?adaptabilité des variétés cultivées à la modification de l?environnement. Dans le cas du peuplier, la sélection de ressources génétiques capables de produire du bois à moindre coût en eau devient alors un critère de choix qui peut être apprécié par l?efficience d?utilisation de l?eau (WUE). De façon à évaluer l?intérêt de développer un programme de sélection sur WUE, il convenait de juger si les variations génétiques de WUE observées sur de jeunes boutures, s?exprimaient encore sur des arbres cultivés en peupleraie sur des sols contrastés. Par ailleurs, afin d?initier une étude du déterminisme moléculaire de WUE, nous avons évalué le degré de variation génétique des protéomes foliaires de huit génotypes de peupliers contrastés pour leur WUE et cultivés dans des conditions d?alimentation en eau variées. Nos travaux ont permis de valider l?existence d?importantes variations génétiques de WUE chez des peupliers cultivés en peupleraie. Toutefois, le type de sol modifiait considérablement le classement des génotypes alors que celui établi sur les sols les plus propices à la populiculture était comparable au classement décrit précédemment en serre. Nos expériences ont également validé la possibilité de distinguer des génotypes contrastés pour WUE à partir de leur protéome foliaire. Nous avons montré que le protéome foliaire de huit génotypes différant par leur WUE présentait d?importantes variations génétiques en réponse à la sécheresse et qu?il existait des liens entre abondances de protéines foliaires et variations génétiques de WUE. / In the actual climate change context, the cultivated varieties will have to cope with the expected environmental modifications. In poplar, the breeding of genetic ressources able to grow with lower water costs becomes therefore, an essential criterion that can be evaluated from water-use efficiency (WUE). In order to assess the interest to develop a breeding program based on WUE, it was agreed to judge if the genetic variation of WUE observed on young cuttings, were still expressed on trees cultivated in poplar plantation on contrasted soils. In addition, in order to initiate a study of the molecular determinism of WUE, we evaluated the degree of genetic variation in the leaf proteome of eight poplar genotypes contrasted for their WUE and cultivated under varied water supply. Our work evidenced consistent genetic variations of WUE in poplars cultivated in a commercial plantation. However, the type of cultivated soil modified considerably the genotypic ranking, whereas ranking established on the most favourable soils for poplar growth, remained comparable with the one described previously in greenhouse. Our experiments also validated the possibility of distinguishing genotypes contrasted for WUE from their leaf proteome. We showed that leaf proteome of eight poplar genotypes differing by their WUE displayed consistent genetic variations in their drought response and that there were relationships between leaf protein abundances and genetic variations of WUE.

A thesis submitted to the Faculty of Science, University of the Witwatersrand, Johannesburg, in fulfilment of the requirements for the degree of Doctor of Philosophy. Johannesburg, 2014. / In the present thesis the use of convergence as a tool in functional analyses was investigated, with special focus on comparisons using distantly related species (“convergence approach”). Guidelines for the convergence approach were forumlated and applied in the evaluation of selected hypotheses on the contextualization of early hominins. Additionally, comprehensive reviews on water use in primates were carried out, with special focus on hominoids, including humans. The first description (and video footage) of swimming and diving behaviour in a common chimpanzee (Pan troglodytes) and an orangutan (Pongo pygmaeus) were presented here, along with swimming behaviour in other great apes (without video footage). Hypotheses on the loss of instinctive swimming in hominoids were discussed and the Saci last common ancestor hypothesis was proposed. This model suggests that the loss of swimming ability in hominoids is best explained as a consequence of phylogenetic constraints linked to the adaptation to an arboreal life in the last common ancestor of this taxon. Furthermore, several hypotheses on early hominin evolution were reviewed. It was pointed out that several of these hypotheses have similar methodological flaws in the use of analogies to corroborate specific arguments. A hypothesis on the emergence of the habitual bipedalism in early hominins was outlined, arguing that this trait did not evolve in association with a locomotory advantage or for other reasons usually presented in the literature, but as a signal to advertise unprofitability – as a warning signal in an anti-predator strategy. It was argued that fossil evidence does not allow a high resolution of inference concerning incipient traits – traits which are not optimized to fulfil a certain function after a functional change. The consideration of different lines of evidence presented in this thesis indicate that the topic “water use” must be considered in discussions on early hominin evolution. The fact that humans regularly and intensively interact with water can be considered as an indication that in some part of human phylogeny after the hominin/panin split, swimming and diving ability was specifically selected. However, contrary to the view of several proponents of the aquatic hypotheses, it was demonstrated that humans are not absolutely unique concerning their ability to learn to swim and to dive. It is therefore also conceivable that our ability to learn to swim is associated to our cognitive abilities and is not a product of specific selection in our past.

Silicon is not considered an essential nutrient, but it is typically abundant in soils and can be taken up in large amounts by plants. Silicon is known to have beneficial effects when added to rice and several other plants. These effects include disease and insect resistance, structural fortification, and regulation of the uptake of other ions. In this study, the effect of silicic acid fertilization on the growth and drought tolerance of four crop plants (corn, wheat, soybean, and rice) was analyzed. Plants were studied using three cultivation techniques: 1) hydroponic solution and subjected to salt stress, 2) low-silicon soil-less medium (peat) and subjected to gradual drought stress, and 3) low-silicon soil-less medium (peat) and subjected to acute drought stress. Silicon was added both as reagent-grade Na2SiO3 and as a siliceous liming agent (PlantTuff). Both forms of Si generally improved drought and salt stress tolerance, but the effects were inconsistent. Silicon increased corn dry mass by up to 18% and the effect was statistically significant (p<0.05) in two out of three techniques. Silicon increased water use efficiency in corn by up to 36% and the effect was statistically significant (p<0.05) in one out of two techniques. In the acute drought stress technique, silicon increased wheat dry mass by 17% and the effect was statistically significant (p<0.05). Silicon increased soybean and rice dry mass by 20 to 30%, but the effect was not statistically significant. Silicon in oldest corn leaves increased from 0.4% to 3% as Si increased from less than 0.01 to 0.8 mM in the hydroponic solution. There was a statistically significant effect of silicon supply on the concentration of some other nutrients, but the effect was often not great enough to be considered biologically important. Rice accumulated the greatest concentration of foliar silicon, corn and wheat were intermediate, and soybean accumulated the least. Collectively, these results indicate an effect of silicon in drought and salinity stress tolerance, but additional studies on the rate and onset of drought are needed to determine interacting factors and better understand the inconsistent results.

The thesis summary is included in the 01front.pdf

Current practices in energized treatments, using gases and foams, remain rudimentary in comparison to other fracturing fluid technologies. None of the available 3D fracturing models for incompressible water-based fluids have been able to capture the thermal and compositional effects that are important when using energized fluids, as their constitutive equations assume single-phase, single-component, incompressible fluid flow. These models introduce a bias in fluid selection because they do not accurately capture the unique behavior of energized fluids. The lack of modeling tools specifically suited for these fluids has hindered their design and field implementation. This work uses a fully compositional 3D fracturing model to answer some of the questions surrounding the design of energized treatments. The new model is capable of handling any multi-component mixture of fluids and chemicals. Changes in fluid density, composition, and temperature are predicted using an energy balance equation and an equation of state. A wellbore model, which relates the surface and bottomhole conditions, determines the pumping requirements. Fracture performance is assessed by a fractured well productivity model that accounts for damage in the invaded zone and finite fracture conductivity. The combination of the fracture, productivity, and wellbore models forms a standalone simulator that is suitable for designing and optimizing energized treatments. The simulator offers a wide range of capabilities, making it suitable for many different applications ranging from hydraulic fracturing to long-term injections for enhanced oil recovery, well clean-up, or carbon sequestration purposes. The model is applicable to any well configuration: vertical, deviated, or horizontal. The resolution of the full 3D elasticity problem enables us to propagate the fracture across multiple layers, where height growth is controlled by the vertical distribution of the minimum horizontal stress. We conducted several sensitivity studies to compare the fracture propagation, productivity, and pumping requirements of various fluid candidates in different reservoirs. The results show that good proppant placement and high fracture conductivities can be achieved with foams and gelled fluid formulations. Foams provide a wide range of viscosities without using excessive amounts of gelling agents. They also provide superior fluid-loss control, as the filter-cake is supplemented by the presence of gas bubbles that reduce liquid-flow into the porous medium. CO₂, LPG, and N₂ expand significantly (by 15% or more) as the reservoir heats the fluid inside the fracture. These fluids show virtually no damage in the invaded zone, which is a significant improvement upon water-based fluids in reservoirs that are prone to water blocking. These results, however, are contingent on an accurate fluid characterization supported by experimental data; therefore, our work advocates for complementary experimental studies on fluid rheology, proppant transport, and fluid leak-off. A comprehensive sensitivity study over a wide range of reservoir conditions identified five key reservoir parameters for fluid selection: relative permeability curve, initial gas saturation, reservoir pressure, changes to rock mechanical properties, and water-sensitivity. Because energized fluids provide similar rheology and leak-off behaviors as water-based fluids, the primary design question it to evaluate the extent of the damaged zone against costs, fluid availability, and/or safety hazards. If the fluid-induced damage is acceptable, water-based fluids constitute a simple and attractive solution; otherwise, energized fluids are recommended. Notably, energized fluids are well-suited for reservoirs that are depleted, under-saturated, and/or water-sensitive. These fluids are also favorable in areas with a limited water supply. As water resources become constrained in many areas, reducing the water footprint and the environmental impact is of paramount concern, thereby making the use of energized treatments particularly attractive to replace or subsidize water in the fracturing process. / text

Hydraulic fracturing has unlocked a tremendous resource across the United States and around the world—shale. However, these processes have also come with a myriad of potential environmental effects, including a substantial demand for water. Hydraulic fracturing can require anywhere between two and four million gallons per well. The need for such large quantities of water can produce severe stresses on local water resources. In response to this issue, operators have developed several ways to alleviate some of the stresses brought on by the extensive water use such as alternative sourcing and reuse technologies. Companies are driven to exercise these options and decrease their fresh water usage for hydraulic fracturing processes for multiple reasons, including changes in regulation, to gain support of local communities, and to increase efficiencies of operations. Whatever the motivation may be, there are a variety of options companies have at their disposal to reduce fresh water demands—dependent on specific formation characteristics, the qualities and quantities of available water, among others. The Eagle Ford shale is one of the most rapidly growing shale plays in the country. However, this formation is located in a fairly arid part of the country. Because of meager average rainfall totals, water availability to meet demand is an issue of great concern. Due to nearly exponential increases in shale production, stresses on local water supplies have dramatically increased as well. The objectives of this thesis are as follows: 1) to establish the enormous resource that has become available; while still recognizing the environmental impacts associated with development processes, focusing primarily on water requirements and associated wastewater production; 2) to break down current water demand for shale development, as well as wastewater management practices in the Eagle Ford, with a brief comparison to other shale plays across the country; 3) to obtain an understanding of operator motivation—what factors affect wastewater management strategies; and 4) to analyze techniques operators presently have at their disposal to reduce fresh water demands, specifically through the use of brackish waters and recycling/reuse efforts, and finally to quantify these efforts to evaluate potential fresh water savings. / text