Understanding water balances is essential for sustainable water resource management, especially in semi-arid basement complex areas where there are large demands for water supplies, but the complex hydrogeological conditions limit groundwater development. This research presents an approach for water balance estimation based on the conceptual and computational modelling of six major landscape unit’s which have been classified on the basis of their differing hydrological responses. Detailed conceptual models of the hydrological processes operating in each of the different landscapes in a catchment and the processes that control water movement between the different landscapes are developed based on data analysis, fieldwork and literature. Two computational models (the WaSim soil water balance model and a new water balance model for bare rock) are used to estimate the daily water balance of each of the landscape units taking cognisance of their interconnectivity which includes runoff becoming run-on. Water balance simulations were run for the individual landscapes using input data from the semi-arid Sokoto Basin in Northwest Nigeria, and outputs for representative wet and dry years are used to demonstrate the reliability of model responses. The individual landscapes outputs were subsequently integrated, taking account of their area weighted contributions, to give a catchment-scale water balance which compares favourably with the observed river discharge at Fokku. The catchment water balance results reveal that AET accounts for the largest loss in the catchment at 72 % of the average rainfall for 37 years. This is followed by the groundwater flow to rivers, then runoff to rivers, representing 16% and 11 % of the average rainfall. This research has provided valuable insights into hydrological behaviour of the basement complex system and the effect of landscape variability on the water balance of these areas. The research suggested a rational approach to groundwater resource management in the basement complex areas that takes cognizance of the hydrological behaviour of different landscape units, focussing on areas with deep weathered material within the catchment identified in this research. The research specifically stresses the need to apply methods of water conservation during excess rainfall for future use in the dry season.

Par le passé la Bretagne a connu des épisodes de sécheresses très intenses. Peu communs pour des régions caractérisées par un climat océanique, ils ont eu des conséquences notables à l'échelle du territoire. De nombreuses activités socio-économiques sont ainsi apparues vulnérables face à ces évènements. Durant la sécheresse de 1976, l'agriculture fut particulièrement touchée, avec des pertes de récoltes importantes. La sécheresse est donc un risque important à l'échelle du territoire breton. Or, le changement du climat observé depuis plusieurs décennies amène des doutes quant à l'évolution des sécheresses en termes de fréquence et d'intensité. Cette thèse propose ainsi une analyse des caractéristiques des épisodes secs en Bretagne selon trois scénarios SRES du GIEC : B1, A1B et A2. Les sorties climatiques désagrégées utilisées ont été comparées, dans un premier temps, aux observations, afin de s'assurer de l'adaptabilité des jeux de données pour une analyse de ce type. Pour chacun des scénarios deux types de bilans hydriques ont été calculés. Ils permettent d'obtenir des valeurs de déficit d'évaporation, paramètre illustrant l'intensité des sécheresses, ainsi que des valeurs de réserve hydrique qui mettent en évidence les périodes d'assèchement et de recharge des sols. Les premiers bilans hydriques, de résolution de 8 km et au pas de temps mensuel, proposent une vision générale sur le comportement hydrique des sols bretons. Les seconds, de résolution kilométrique et au pas de temps journalier, apportent plus de précision quant aux secteurs vulnérables et à l'intensité probable des épisodes secs. On peut ainsi voir que des sécheresses exceptionnelles, similaires à celle de 1976, seraient régulièrement observées à la fin du 21ème siècle d'après le scénario A2. La comparaison avec un indice de sécheresse utilisé par Météo-France confirme les tendances régionales attendues au 21ème siècle d'après les trois scénarios SRES. Une approche agronomique est également proposée dans cette thèse afin d'apprécier les impacts de différentes types de culture sur la réserve hydrique des sols / Several extreme droughts occurred in Brittany during the past. Although they are rare in this oceanic region, their impacts are noticeable on the territory. Several socio-economical activities thus appeared to be vulnerable to dryness. In 1976, agriculture has been highly impacted during the drought, with important harvest loss. Droughts are therefore a significant hazard in Brittany. However, the changing climate observed for several decades raises issues on the way drought events might evolve in terms of frequency and intensity. This thesis offers an analysis of drought's characteristics in Brittany according to three IPCC's SRES scenarios : B1, A1B and A2. At first, disaggregated climate outputs have been compared to observed data to make sure of their suitability for this kind of study. For each scenario, two soil water balances have been calculated in order to get values of evaporation deficit, quantifying drought intensity, and of water storage, illustrating periods of emptying and filling of soils. Soil water balances calculated at a 8-km spatial resolution and monthly timescale displayed a general view of water content in Britannic's soils. Soil water balances calculated at a higher spatial resolution (1 km) and daily timescale brought more details than previous results in terms of intensity and localization of droughts. They revealed that droughts of similar intensity than that of 1976 might occur regularly at the end of the 21st century according to the A2 scenario. These results are confirmed by another drought index used by Météo-France. An agronomic approach is also developed in this thesis in order to reveal impacts of farming on soil water content

O Brasil é o maior produtor de cana-de-açúcar do mundo, com produção de 734 milhões de toneladas em 2011 (41% da produção mundial), sendo apontado como líder no setor de bioenergia. A aplicação de vinhaça, resíduo da fabricação do álcool, como fertilizante na cultura da cana-de-açúcar tem se tornado frequente, aumentando também a preocupação com seu potencial poluente. Estudos sobre o tema culminaram em uma instrução normativa (P4.231) da Companhia de Tecnologia de Saneamento Ambiental do Estado de São Paulo (CETESB), cuja dose recomendada baseia-se nas concentrações de K+ no solo e na vinhaça. A presente pesquisa teve como objetivo avaliar a percolação da vinhaça no solo aplicada via gotejamento subsuperficial em um Nitossolo Vermelho Eutrófico, considerando-se a hipótese de que a dose recomendada depende também da dinâmica de água e íons no solo. Para tanto, foram aplicados seis tratamentos: T1 (Sem irrigação + adubação convencional); T2 (Fertirrigação + sem vinhaça); T3 (Fertirrigação + 1/2 dose CETESB); T4 (Fertirrigação + 1 dose CETESB); T5 (Fertirrigação + 2 doses CETESB) e T6 (Fertirrigação + 3 doses CETESB). As variáveis condutividade elétrica, pH e as concentrações dos íons K+, Ca2+, Mg2+, Na2+, SO4- e NO3-, na solução do solo, foram analisadas por meio de análises multivariadas; enquanto variáveis de produção (colmos e ponteiras) e características tecnológicas (Brix, Pol, Açúcares Redutores, Pureza, Fibra, Açúcares redutores totais, Açúcar total recuperável e Cinzas) foram analisadas pela estatística convencional. Um balanço de água foi realizado na área experimental, considerando a camada de 0 a 0,8 m de solo. A partir dos resultados obtidos neste experimento, concluiu-se que a quantidade de vinhaça aplicada ao solo depende não somente dos teores de potássio no solo e na vinhaça, mas também da dinâmica da água e de íons na solução. Em função da aplicação, houve aumento para todas as variáveis analisadas da solução do solo, com exceção para o íon nitrato. Há risco de enriquecimento do lençol freático, se este estiver presente e ascender até próximo de 0,8 m da superfície do solo, independente das doses aplicadas. As variáveis de produção e tecnológicas, com exceção para teor de cinzas, não foram afetadas pelas aplicações. / Brazil is the world\'s largest sugarcane producer, with 734 millions of tons in 2011 (41% of the world\'s production), being considered a leader in the bioenergy sector. The application of vinasse, a byproduct in the ethanol production process, as a fertilizer on sugarcane has become frequent, increasing thus the concern with its polluting potential. Studies on this subject have culminated in a normative instruction (P4.231) of the Environmental Protection Agency of São Paulo State (CETESB), of which the recommended dose is based on the K+ concentrations in both soil and vinasse. This study aimed to verify vinasse percolation in soil applied via subsurface drip irrigation in a Nitossolo considering the hypothesis that the recommended dose depends also upon the water and ion dynamics in soil. For that, six treatments were applied: T1 (No irrigation + conventional fertilization); T2 (Fertigation + no vinasse); T3 (Fertigation + 1/2 CETESB dose); T4 (Fertigation + 1 CETESB dose); T5 (Fertigation + 2 CETESB doses) e T6 (Fertigation + 3 CETESB doses). Multivariate statistical analysis was used to evaluate electrical conductivity, pH, and the concentrations of K+, Ca2+, Mg2+, Na2+, SO4- and NO3- in the soil solution; while conventional statistical analysis was used for sugarcane production (stalk and tops) and technological characteristics (Brix, Pol, Reducing sugar, Purity, Fiber, Total reducing sugar, Total recoverable sugar and Ash percentage). A water balance was performed in the experimental area, considering the soil layer of 0-0.8 m. From the obtained results, it was concluded that the amount of vinasse applied on soil depends not only on the potassium contents in the vinasse and soil, but also on water and ion dynamics. As a result of the application, there was an increase for all the variables analyzed in the soil solution, except for nitrate. There is risk of groundwater enrichment, if it is present and ascends to close to 0.8 m from the soil surface, regardless of the applied doses. Technological and yield variables, except for ash content, were not affected by the applications.

O Brasil é o maior produtor de cana-de-açúcar do mundo, com produção de 734 milhões de toneladas em 2011 (41% da produção mundial), sendo apontado como líder no setor de bioenergia. A aplicação de vinhaça, resíduo da fabricação do álcool, como fertilizante na cultura da cana-de-açúcar tem se tornado frequente, aumentando também a preocupação com seu potencial poluente. Estudos sobre o tema culminaram em uma instrução normativa (P4.231) da Companhia de Tecnologia de Saneamento Ambiental do Estado de São Paulo (CETESB), cuja dose recomendada baseia-se nas concentrações de K+ no solo e na vinhaça. A presente pesquisa teve como objetivo avaliar a percolação da vinhaça no solo aplicada via gotejamento subsuperficial em um Nitossolo Vermelho Eutrófico, considerando-se a hipótese de que a dose recomendada depende também da dinâmica de água e íons no solo. Para tanto, foram aplicados seis tratamentos: T1 (Sem irrigação + adubação convencional); T2 (Fertirrigação + sem vinhaça); T3 (Fertirrigação + 1/2 dose CETESB); T4 (Fertirrigação + 1 dose CETESB); T5 (Fertirrigação + 2 doses CETESB) e T6 (Fertirrigação + 3 doses CETESB). As variáveis condutividade elétrica, pH e as concentrações dos íons K+, Ca2+, Mg2+, Na2+, SO4- e NO3-, na solução do solo, foram analisadas por meio de análises multivariadas; enquanto variáveis de produção (colmos e ponteiras) e características tecnológicas (Brix, Pol, Açúcares Redutores, Pureza, Fibra, Açúcares redutores totais, Açúcar total recuperável e Cinzas) foram analisadas pela estatística convencional. Um balanço de água foi realizado na área experimental, considerando a camada de 0 a 0,8 m de solo. A partir dos resultados obtidos neste experimento, concluiu-se que a quantidade de vinhaça aplicada ao solo depende não somente dos teores de potássio no solo e na vinhaça, mas também da dinâmica da água e de íons na solução. Em função da aplicação, houve aumento para todas as variáveis analisadas da solução do solo, com exceção para o íon nitrato. Há risco de enriquecimento do lençol freático, se este estiver presente e ascender até próximo de 0,8 m da superfície do solo, independente das doses aplicadas. As variáveis de produção e tecnológicas, com exceção para teor de cinzas, não foram afetadas pelas aplicações. / Brazil is the world\'s largest sugarcane producer, with 734 millions of tons in 2011 (41% of the world\'s production), being considered a leader in the bioenergy sector. The application of vinasse, a byproduct in the ethanol production process, as a fertilizer on sugarcane has become frequent, increasing thus the concern with its polluting potential. Studies on this subject have culminated in a normative instruction (P4.231) of the Environmental Protection Agency of São Paulo State (CETESB), of which the recommended dose is based on the K+ concentrations in both soil and vinasse. This study aimed to verify vinasse percolation in soil applied via subsurface drip irrigation in a Nitossolo considering the hypothesis that the recommended dose depends also upon the water and ion dynamics in soil. For that, six treatments were applied: T1 (No irrigation + conventional fertilization); T2 (Fertigation + no vinasse); T3 (Fertigation + 1/2 CETESB dose); T4 (Fertigation + 1 CETESB dose); T5 (Fertigation + 2 CETESB doses) e T6 (Fertigation + 3 CETESB doses). Multivariate statistical analysis was used to evaluate electrical conductivity, pH, and the concentrations of K+, Ca2+, Mg2+, Na2+, SO4- and NO3- in the soil solution; while conventional statistical analysis was used for sugarcane production (stalk and tops) and technological characteristics (Brix, Pol, Reducing sugar, Purity, Fiber, Total reducing sugar, Total recoverable sugar and Ash percentage). A water balance was performed in the experimental area, considering the soil layer of 0-0.8 m. From the obtained results, it was concluded that the amount of vinasse applied on soil depends not only on the potassium contents in the vinasse and soil, but also on water and ion dynamics. As a result of the application, there was an increase for all the variables analyzed in the soil solution, except for nitrate. There is risk of groundwater enrichment, if it is present and ascends to close to 0.8 m from the soil surface, regardless of the applied doses. Technological and yield variables, except for ash content, were not affected by the applications.

abstract: Environmental changes are occurring at an unprecedented rate, and these changes will undoubtedly lead to alterations in resource availability for many organisms. To effectively predict the implications of such changes, it is critical to better understand how organisms have adapted to coping with seasonally limited resources. The vast majority of previous work has focused on energy balance as the driver of changes in organismal physiology. While energy is clearly a vital currency, other resources can also be limited and impact physiological functions. Water is essential for life as it is the main constituent of cells, tissues, and organs. Yet, water has received little consideration for its role as a currency that impacts physiological functions. Given the importance of water to most major physiological systems, I investigated how water limitations interact with immune function, metabolism, and reproductive investment, an almost entirely unexplored area. Using multiple species and life stages, I demonstrated that dehydrated animals typically have enhanced innate immunity, regardless of whether the dehydration is a result of seasonal water constraints, water deprivation in the lab, or high physiological demand for water. My work contributed greatly to the understanding of immune function dynamics and lays a foundation for the study of hydration immunology as a component of the burgeoning field of ecoimmunology. While a large portion of my dissertation focused on the interaction between water balance and immune function, there are many other physiological processes that may be impacted by water restrictions. Accordingly, I recently expanded the understanding of how reproductive females can alter metabolic substrates to reallocate internal water during times of water scarcity, an important development in our knowledge of reproductive investments. Overall, by thoroughly evaluating implications and responses to water limitations, my dissertation, when combined previous acquired knowledge on food limitation, will enable scientists to better predict the impacts of future climate change, where, in many regions, rainfall events are forecasted to be less reliable, resulting in more frequent drought. / Dissertation/Thesis / Doctoral Dissertation Biology 2019

This thesis evaluates the surface water hydrology in an artificially drained and farmed prairie pothole wetland located in north-central Iowa as part of the Iowa DNR Wetland Program Development (WPD) project. The purpose of the WPD project was to begin documentation of basic hydrology, wildlife value, and water quality to improve understanding of ecosystem services provided by drained prairie pothole wetlands. The surface water hydrology was evaluated using a daily water balance (PPWB) model. The model development, validation, and applications are described in detail in this thesis. The PPWB model estimates the water depth and duration in the drained wetland. Several sensitivity analyses were performed to evaluate how site-specific factors affect the frequency, depth, and duration of surface ponding in the drained wetland. In the absence of surface inlets, infiltration was found to have a significant impact on ponding, second only to the amount of precipitation in importance. The topography also plays an important role in surface water ponding, with higher ponding durations occurring for larger catchment-to-pothole area ratios. However, the presence of a surface inlet in a drained prairie pothole wetland significantly alters the hydrology and all other ponding factors become negligible. In addition, long-term ponding was evaluated for historic and future hydrologic trends. The long-term simulation showed increasing trends for precipitation and ponding duration. The possible implications of continued farming of drained wetlands were explored using PPWB model sensitivity analysis and long-term simulation results. Agricultural implications include mitigation strategies to balance ecosystem needs with crop production and impacts of the projected future outlook with regards to climate. Environmental implications include insight on impacts of wetland restoration.

The Upper Ovens River catchment is located in the Victorian high plains of Australia. With an absence of major storages or weirs, the flow regime of the Upper Ovens River is close to its natural magnitude and frequency. Water extraction from rivers has the potential to negatively impact on environmental flow requirements and management of extraction is required to maintain flows to the river, especially over the low flow summer periods. The Upper Ovens River has been shown to have a high connectivity between groundwater and surface water, and for effective protection of stream flow, it is proposed that groundwater and surface water are managed conjunctively by a government legislated Water Management Plan. Environmental stream flow objectives have been identified, but no method exists to link these to groundwater objectives. Without this link, water resource managers cannot develop management methods or plans for management of groundwater to achieve surface flow objectives. / Existing data commonly available to water resource managers was analysed to develop a method to link stream flow objectives to groundwater management objectives, and investigate the groundwater-surface water relationship and water cycle in the Upper Ovens catchment. A water balance for a well defined sub-catchment was developed for the period between 1975 and 2005 to investigate the water cycle and magnitude of fluxes between groundwater in the unconsolidated sediments of the valleys and surface water. Darcy’s law and statistical regression analysis of commonly available historic data were used to develop the understanding of the groundwater-river level relationship and produce a method for relating environmental river flow targets to groundwater levels. A set of conjunctive management principles for resource managers was produced based upon the sound scientific understanding of groundwater-surface water interactions. / The mean water balance shows a clear seasonal pattern for movement of water between surface water and groundwater. Groundwater levels have remained steady, with average annual groundwater recharge from rainfall and the river of 9,773 ML nearly equal to average annual discharge of 9,584 ML from the aquifer as baseflow or evaporation in the dry season. Generally extraction of groundwater and surface water (3,200 ML/yr) and fluxes between groundwater and the river (2,626 ML/yr), are only minor components of the water balance (560,000 ML/yr) and do not affect the flow patterns in the Ovens River. However, in years with very low flows over the Summer/Autumn period, extraction from the river can significantly reduce flow in the river. Management of river flow at this time is the focus for water resource managers. / Field measurements and regression relationships showed a rapid rate of flux between groundwater and the river with the time lag (for rises in river level to subsequent rises in groundwater levels) increasing with distance of the aquifer from the river to be 14-20 days at the maximum measured distance of 750 metres from the river. With the narrow width of the unconsolidated sediment aquifer (less than 3000 metres) extraction of groundwater from these aquifers is expected to impact on stream flows within the summer period (90 days). / Regression analysis produced equations for relating Ovens River levels to groundwater levels with a high correlation. These equations can relate stream flow objectives to corresponding groundwater management that can be used by resource managers with a high level of confidence. Groundwater and surface water, in the form of river flows, are intrinsically linked and to protect flows in the Ovens River during times of low flow, groundwater has to be managed in line with surface water. Four principles have been identified for conjunctive management in the Upper Ovens, and resource managers should set management rules based on the following principles: 1) Groundwater and surface water are hydraulically connected, manage as one; 2) Restrict groundwater extraction in line with surface water restrictions; 3) Manage groundwater to minimum groundwater levels; and 4)Manage groundwater in the unconsolidated sediments as one aquifer.

Pearl millet [Pennisetum glaucum (L.) R.Br.] production under subsistence farmer management on the sandy soils of southwestern Niger is faced with many challenges, including declining soil fertility, highly variable and scarce rainfall and poor resource base of the peasant farmers in the region. This study was conducted to evaluate the potential of management to increase yield and water use efficiency of pearl millet grown on two farmers’ fields in Niger during two growing seasons, 2003 and 2004. The management practices tested were: 1) Five manure treatments (no manure, transported manure, current corralling, a year after corralling, and two years after corralling); 2) The microdose technology (20 kg di-ammonium phosphate ha-1, and 20 kg di-ammonium phosphate ha-1 + 10 kg urea ha-1); and lastly, 3) Three different pearl millet cultivars (Heini Kirei, Zatib, and ICMV IS 89305). In both growing seasons, manure had the greatest effect on the yield and water use of pearl millet at both sites. In 2003 grain yields were 389 kg ha-1 in the NM treatment and 1495 kg ha-1 in the C0 treatment at Banizoumbou whereas at Bagoua, the NM treatment had 423 kg ha-1 vs. 995 kg ha-1 in the C0 treatment. In 2004, the NM treatment at Banizoumbou had 123 kg ha-1 grain yield and the C0 treatment had 957 kg ha-1 whereas at Bagoua the NM treatment had 506 kg ha-1 vs. 1152 kg ha-1 in the C0 treatment. Residual effects of manure led to grain yields in the C1 and C2 treatments which were more than twice as high as in the NM treatment. The improved cultivars were generally superior for grain yields, whereas the local landrace was superior for straw yields at both sites. Root zone drainage was decreased by between 50 to 100 mm, and water use increased by the same amount in the current corrals at the two sites during the two growing seasons. Increased water use under corralling and presence of residual profile moisture at the end of each of the two seasons suggested that water did not limit pearl millet production at the two sites.

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This study quantifies spatial and temporal patterns in snow water equivalent (SWE), chemistry, and water isotopes associated with snowpack shading due to aspect and vegetation in the Valles Caldera National Preserve, New Mexico. Depth, density, stratigraphy, temperature, and snow chemistry, isotope, and biogeochemical nutrient samples were collected and analyzed from five snowpit locations on approximate monthly intervals between January-April 2007. SWE showed little variability between sites in January (~10mm) but differences expanded to 84mm (30%) by max accumulation in open sites and 153mm (45%) between all sites. Sulfate varied by 22% (10.6-13.5 microeq/L), Cl- by 35% (17.4-26.9 microeq/L), and d18O by 17% (-16.3 to -13.5), with SWE exhibiting inverse correlations with d18O (r2=0.96), SO42- (r2=0.75), and Cl- (r2=0.60) at max accumulation. Regression relationships suggest variability in SWE and solutes/water isotopes are primarily driven by sublimation. Mass balance techniques estimate sublimation ranges from 1-16% between topographically- and non-shaded open sites.