abstract: Land surface fluxes of energy and mass developed over heterogeneous mountain landscapes are fundamental to atmospheric processes. However, due to their high complexity and the lack of spatial observations, land surface processes and land-atmosphere interactions are not fully understood in mountain regions. This thesis investigates land surface processes and their impact on convective precipitation by conducting numerical modeling experiments at multiple scales over the North American Monsoon (NAM) region. Specifically, the following scientific questions are addressed: (1) how do land surface conditions evolve during the monsoon season, and what are their main controls?, (2) how do the diurnal cycles of surface energy fluxes vary during the monsoon season for the major ecosystems?, and (3) what are the impacts of surface soil moisture and vegetation condition on convective precipitation? Hydrologic simulation using the TIN-based Real-time Integrated Basin Simulator (tRIBS) is firstly carried out to examine the seasonal evolution of land surface conditions. Results reveal that the spatial heterogeneity of land surface temperature and soil moisture increases dramatically with the onset of monsoon, which is related to seasonal changes in topographic and vegetation controls. Similar results are found at regional basin scale using the uncoupled WRF-Hydro model. Meanwhile, the diurnal cycles of surface energy fluxes show large variation between the major ecosystems. Differences in both the peak magnitude and peak timing of plant transpiration induce mesoscale heterogeneity in land surface conditions. Lastly, this dissertation examines the upscale effect of land surface heterogeneity on atmospheric condition through fully-coupled WRF-Hydro simulations. A series of process-based experiments were conducted to identify the pathways of soil moisture-rainfall feedback mechanism over the NAM region. While modeling experiments confirm the existence of positive soil moisture/vegetation-rainfall feedback, their exact pathways are slightly different. Interactions between soil moisture, vegetation cover, and rainfall through a series of land surface and atmospheric boundary layer processes highlight the strong land-atmosphere coupling in the NAM region, and have important implications on convective rainfall prediction. Overall, this dissertation advances the study of complex land surface processes over the NAM region, and made important contributions in linking complex hydrologic, ecologic and atmospheric processes through numerical modeling. / Dissertation/Thesis / Doctoral Dissertation Civil and Environmental Engineering 2016

The increasing demand for water resources, for the most diverse purposes, has evidenced a still deficient scenario in relation to fluviometric monitoring, especially in river basins with areas smaller than 1000 km², in large part of the regions of Brazil. Inevitably, these demands are linked to water availability and your determination in lack of measured data becomes necessary to resort to techniques such as regionalization of flows, or the simulation through rain-flow models. However, a period of hydrological monitoring data is still necessary to enable the application of these methodologies. In 1997 it was proposed a method that uses a few samplings of local flow measurements for the determination of the minimum flows through a rain-flow model, whose mathematical process involves two parameters, the Cinf and the Ksub. The first is related to water balance and the second to the river depletion. The objective of this work was to verify the influence of precipitation in the application of this methodology in basins between 800 and 1000 km² in order to subsidize information about the elaboration of a protocol of use of the method. For the case study, four basins with areas between 817 and 965 km² were used, with the availability of fluviometric and pluviometric data series. The methodology used was based on the Silveira method. Initially, rainfall scenarios were elaborated in the four basins for later selection of the drought events, which along with the rainfall scenarios, resulted in a total of 1407 simulations using the Silveira method. For each simulation, a flow continuity curve was generated. The determination of the errors was performed between the pairs of simulated flows and those observed for the considered percentiles. It was observed a tendency of improvement in the results of the simulations, translated by the smaller dispersion of errors, when the precipitation information from more than one pluviometric station is used. Regarding the spatial position of the pluviometric stations, it was verified that there were no significant impacts on the errors when data from the stations located at different points inside the basin and your surroundings. / A crescente demanda pelos recursos hídricos, para as mais diversas finalidades, tem evidenciado um cenário ainda deficitário em relação ao monitoramento fluviométrico, sobretudo em bacias hidrográficas com áreas inferiores a 1000 km², em grande parte das regiões do Brasil. As demandas estão vinculadas a disponibilidade hídrica e para a sua determinação em locais com carência de dados medidos torna-se necessário recorrer a técnicas como a regionalização de vazões, ou a simulação por meio de modelos chuva-vazão. Em 1997 foi proposto um método que se utiliza de poucas amostragens de medições de vazões locais para a determinação das vazões mínimas por meio de um modelo chuva-vazão, cujo processo matemático envolve dois parâmetros, o Cinf e o Ksub. O primeiro está relacionado ao balanço hídrico e o segundo ao deplecionamento fluvial. O objetivo desse trabalho foi verificar a influência da precipitação na aplicação dessa metodologia em bacias entre 800 a 1000 km² visando subsidiar informações acerca da elaboração de um protocolo de uso do método. Para o estudo de caso utilizaram-se quatro bacias com áreas entre 817 e 965 km² com disponibilidade de séries de dados fluviométricos e pluviométricos. A metodologia utilizada foi baseada no método Silveira. Inicialmente foram elaborados cenários de chuvas nas quatro bacias para posterior seleção dos eventos de estiagem, que juntamente com os cenários de chuvas, resultaram em um total de 1407 simulações por meio do uso do método Silveira. Para cada simulação foi gerada uma curva de permanência das vazões. A determinação dos erros foi realizada entre os pares de vazões simulados e os observados para os percentis considerados. Observou-se uma tendência de melhora nos resultados das simulações, traduzido pela menor dispersão dos erros, quando se utiliza informações de precipitação de mais de um posto pluviométrico. Com relação à posição espacial dos postos pluviométricos, verificou-se que não houve impactos significativos nos erros quando se utilizou dados dos postos localizados em diferentes pontos no interior da bacia e no seu entorno.

Finally, the newly integrated model was firstly applied to analyze the relationship of land use and hydrologic regimes based on the land use maps in 1980 and 2000. Then the newly integrated model was applied to simulate the potential impacts of land use change on hydrologic regimes in the East River Basin under a series of hypothetical scenarios. The results show that ET has a positive relationship with Leaf Area Index (LAI) while runoff has a negative relationship with LAI in the same climatic zone, which can be elaborated by surface energy balance and water balance equation. Specifically, on an annual basis, ET of forest scenarios is larger than that of grassland or cropland scenarios. On the contrary, runoff of forest scenarios is less than that of grassland or cropland scenarios. On a monthly basis, for most of the scenarios, particularly the grassland and cropland scenarios, the most significant changes occurred in the rainy season. The results indicate that deforestation would cause increase of runoff and decrease of ET on an annual basis in the East River Basin. On a monthly basis, deforestation would cause significant decrease of ET and increase of runoff in the rainy season in the East River Basin. / In order to effectively simulate hydrologic impact of LUCC, an integrated model of ESEBS and distributed monthly water balance model has been developed in this study. The model is capable of considering basin terrain and the spatial distribution of precipitation and soil moisture. Particularly, the model is unique in accounting for spatial and temporal variations of vegetation cover and ET, which provides a powerful tool for studying the hydrologic impacts of LUCC. The model was applied to simulate the monthly runoff for the period of 1980-1994 for model calibration and for the period of 1995-2000 for validation. The calibration and validation results show that the newly integrated model is suitable for simulating monthly runoff and studying hydrologic impacts ofLUCC in the East River Basin. / Land use/cover change (LUCC) has significantly altered the hydrologic system in the East River (Dongjiang) Basin. Quantitative modeling of hydrologic impacts of LUCC is of great importance for water supply, drought monitoring and integrated water resources management. An integrated eco-hydrologic modeling system of Distributed Monthly Water Balance Model (DMWBM), Surface Energy Balance System (SEBS) was developed with aid of GIS/RS to quantify LUCC, to conduct physically-based ET (evapotranspiration) mapping and to predict hydrologic impacts of LUCC. / The physically-remote-sensing-based Surface Energy Balance System (SEBS) was employed to estimate areal actual ET for a large area rather than traditional point measurements . The SEBS was enhanced for application in complex vegetated area. Then the inter-comparison with complimentary ET model and distributed monthly water balance model was made to validate the enhanced SEBS (ESEBS). The application and test of ESEBS show that it has a good accuracy both monthly and annually and can be effectively applied in the East River Basin. The results of ET mapping based on ESEBS demonstrate that actual ET in the East River Basin decreases significantly in the last two decades, which is probably caused by decrease of sunshine duration. / These results are not definitive statements as to what will happen to runoff, ET and soil moisture regimes in the East River Basin, but rather offer an insight into the plausible changes in basin hydrology due to land use change. The integrated model developed in this study and these results have significant implications for integrated water resources management and sustainable development in the East River Basin. / To begin with, in order to evaluate LUCC, understand implications of LUCC and provide boundary condition for the integrated eco-hydrologic modeling, firstly the long-term vegetation dynamics was investigated based on Normalized Difference Vegetation Index (NDVI) data, and then LUCC was analyzed with post-classification methods and finally LUCC prediction was conducted based on Markov chain model. The results demonstrate that the vegetation activities decreased significantly in summer over the years. Moreover, there were significant changes in land use/cover over the past two decades. Particularly there was a sharp increase of urban and built-up area and a significant decrease of grassland and cropland. All these indicate that human activities are intensive in the East River Basin and provide valuable information for constructing scenarios for studying hydrologic impacts of LUCC. / Wang, Kai. / "December 2010." / Adviser: Yongqin Chen. / Source: Dissertation Abstracts International, Volume: 73-04, Section: A, page: . / Thesis (Ph.D.)--Chinese University of Hong Kong, 2011. / Includes bibliographical references (leaves 203-227). / Electronic reproduction. Hong Kong : Chinese University of Hong Kong, [2012] System requirements: Adobe Acrobat Reader. Available via World Wide Web. / Electronic reproduction. [Ann Arbor, MI] : ProQuest Information and Learning, [201-] System requirements: Adobe Acrobat Reader. Available via World Wide Web. / Abstract also in Chinese.

xii, 60 p. : ill. (some col.) / Exurban growth is prevalent in watersheds nationwide and of special concern in areas important for their undeveloped qualities. The McKenzie River, Oregon, is a natural amenity of great public, aesthetic and recreational value and provides drinking water for much of the southern Willamette Valley. These qualities also make the basin an attractive place to live, and their preservation is often in conflict with the rights and gains of private landowners. However, current containment strategies of development can be arbitrary from a hydrological perspective, especially when adapted from urban contexts. This study introduces a spatially-explicit and physically-based approach for identifying hydrologically sensitive lands in periurban watersheds and then applies that model as a framework for assessing current risk to municipal drinking water sources from exurban residential development. / Committee in charge: Robert Parker, Chair; David Hulse, Member; Scott Bridgham, Member

Doctor of Philosophy / Department of Biological & Agricultural Engineering / James K. Koelliker / Over the past decades, it has been observed that the streamflow characteristics in the Great Plains rivers have substantially changed. These changes have affected and will continue to affect the management decisions within the watershed. This study was undertaken to document the changes for some unregulated streams in Kansas, characterize the streams in terms of some hydrologic indices, and identify the probable factors influencing the changes. Fourteen unregulated streams with 60 or more years of daily discharge data geographically distributed across the state were used. The analysis focused on hydrologic indices judged to be relevant to the lotic ecosystem. The state was divided into four regions, representing roughly the northwest, southwest, northeast and southeast sections of the state. Log Pearson III method was used for computing flow probabilities, Mann-Kendall test in conjunction with Sen’s slope estimator was used for trend analysis, whereas the indicators of hydrologic alterations software was used to generate most hydrologic indices. Several factors believed to affect the streamflow were identified, and their influence was modeled over time. A multi-variate statistical model was run. Results show that there is substantial difference in the streamflow characteristics between the western and eastern regions. Many streamflow aspects have changed over time, and a number of them show significant and important change. Most streams in western Kansas have longer and more frequent dry periods. Potential recharge rate, land use, water use, soil and water conservation practices, and soil type were significant factors influencing the median to very low flow, but the effect varied among the regions. Results of this study could be useful to decision makers, water users, watershed stakeholders, and environmental conservation advocates in addressing problems and concerns related to stream and river management.

Submitted in fulfillment of the requirements for the degree of Master of Engineering, Department of Civil Engineering and Surveying, Durban University of Technology, Durban, South Africa, 2016. / Due to the water scarcity in South Africa, new strategies in management planning are needed in order to sustain water resources. The increase of population and economic growth in South Africa has a negative effect on the water resources. Therefore, it should be well managed. The main concerns of the sustainability of water resources are hydropower, irrigation for agriculture, domestic and industries. Hence, the use of integrated water resources management in a single system which is built up by a river basin will help in water resources. This study was focused on water management issues: some of the principal causes of water shortages in UMdloti River are discussed. The current situation of water supply and demand at present is discussed. It also addressed some essential elements of reasonable, cooperative and sustainable water resources management solutions. Many developing countries are characterized as there is limited data availability, water scarcity and decrease of water levels in the dams. The eThekwini municipality is also having similar problems. Water resources have been modelled under this limited data using the hydrological modelling techniques by assessing the streamflow and observed data. The aim of the study was to address the issue of water management how water supply sources can be sustained to be manageable to meet the population growth demand considering the capacity of Hazelmere Dam demand downstream of the dam. Hydrological models, simulation, and decision making support systems were used to achieve all the research objectives. Hazelmere Dam has been modelled so that it can be used efficiently for the benefit of all users downstream of the dam for their economic and ecological benefits. Monthly reservoir inflow data for Hazelmere Dam was obtained from the Department of Water Affairs, South Africa. The nature of data is streamflow volume in mega liter (Ml) recorded for every month of the year. This was converted to mega cubic meter (Mm3) for use in the analysis herein. A period spanning 19 years of data (1994 – 2013) was used for the analysis. Six parametric probability distribution models were developed for estimating the monthly streamflow at Hazelmere Dam. These probability distribution functions include; Normal, Log-Normal (LN), Pearson III, Log-Pearson type III (LP3), Gumbel extreme value type1 (EVI) and Log-Gumbel (LG). It was observed that UMdloti River is smaller when compared with other rivers within the KwaZulu-Natal Province which could make it difficult to implement integrated water resources management. The hydro-meteorological data collected also has some limitations. The meteorological stations are far away to one another and this would make it difficult to attach their readings with the corresponding water basin. The comparison between the observed and simulated streamflow indicated that there was a good agreement between the observed and simulated discharge. Even though, the performance of the model was satisfactory, yet, it should not be generalized equally for all purposes. The erosion on the study area must be addressed by the stakeholders. It must be minimized in order to sustain the water resources of the UMdloti River. Erosion has a bad impact on the environment because it causes environmental degradation as well. Further investigations are recommended that account for the geological characteristics and the source of the base flow to make sure the rate of groundwater is sufficient for any future developments. Harnessing more energy from existing water sources within the frontier of the country is important in capacitating the South African Government’s commitment to reduction of the country’s greenhouse gas emissions and transition to a low-carbon economy while meeting a national target of 3,725 megawatts by 2030. This study also aimed to determine the amount of energy that can be generated from Hazelmere Dam on the uMdloti River, South Africa. Behavioral analyses of the Hazelmere reservoir were performed using plausible scenarios. Feasible alternative reservoir operation models were formulated and investigated to determine the best operating policy and power system configuration. This study determines the amounts of monthly and total annual energy that can be generated from Hazelmere reservoir based on turbines efficiencies of 75%, 85% and 90%. Optimization models were formulated to maximize hydropower generation within the constraints of existing abstractions, hydrological and system constraints. Differential evolution (DE) optimization method was adopted to resolve the optimization models. The methodology was applied for an operating season. The optimization models were formulated to maximize hydropower generation while keeping within the limits of existing irrigation demands. Differential evolution algorithm was employed to search feasible solution space for the best policy. Reservoir behavioural analysis was conducted to inspect the feasibility of generating hydropower from the Hazelmere reservoir under normal flow conditions. Optimization models were formulated to maximize hydropower generation from the dam. DE was employed to resolve the formulated models within the confines of the system constraints. It was found that 527.51 MWH of annual energy may be generated from the dam without system failure. Storage was maintained above critical levels while the reservoir supplied the full demands on the dam throughout the operating period indicating that the system yield is sufficient and there is no immediate need to augment the system. / M

<p>The contribution of surface evapotranspiration (ET) to moist convection, cloudiness and precipitation along the eastern flanks of the Andes (EADS) was investigated using the Weather Research and Forecasting (ARW-WRF3.4.1) model with nested simulations of selected weather conditions down to 1.2 km grid spacing. To isolate the role of surface ET, numerical experiments were conducted using a quasi-idealized approach whereby at every time step the surface sensible heat effects are exactly the same as in the reference simulations, whereas the surface latent heat fluxes are prevented from entering the atmosphere. </p><p>Energy balance analysis indicates that local surface ET along the EADS influences moist convection primarily through its impact on conditional instability, because it acts as an important source of moist entropy in this region. The energy available for convection decreases by up to ~60% when the ET contribution is withdrawn. In contrast, when convective motion is not thermally driven, or under conditionally stable conditions, latent heating from the land surface becomes secondary. At the scale of the Andes proper, removal of surface ET weakens upslope flows by increasing static stability of the lower troposphere, as the vertical gradient of water vapor mixing ratio tends to be less negative. Consequently, moisture convergence is reduced over the EADS. In the absence of local surface ET, this process operates in concert with damped convective energy, suppressing cloudiness, and decreasing daily precipitation by up to ~50% in the simulations presented here.</p><p>When the surface ET is eliminated over the Amazon lowlands (AMZL), the results show that, without surface ET, daily precipitation within the AMZL drops by up to ~75%, but nearly doubles over the surrounded mountainous regions. This dramatic influence is attributed to a dipole structure of convergence-divergence anomalies over the AMZL, primarily due to the considerable cooling of the troposphere associated with suppressed convection. Further examination of moist static energy evolution indicates that the net decrease in CAPE (Convective Available Potential Energy) over the AMZL is due to the removal of surface ET that is only partially compensated by related regional circulation changes. Because of the concave shape of the Andean mountain range, the enhanced low-level divergence promotes air mass accumulation to the east of the central EADS. This perturbation becomes sufficiently strong around nightfall and produces significant eastward low-level pressure gradient force, rendering wind currents more away from the Andes. Moisture convergence and convection over the EADS vary accordingly, strengthened in the day but attenuated at night. Nocturnal convective motion, however, is more widespread. Analytical solutions of simplified diagnostic equations of convective fraction suggest that reduction of lower troposphere evaporation is the driving mechanism. Additional exploratory experiments mimicking various levels of thinning and densification of AMZL forests via changes in surface ET magnitude demonstrate that the connection between the AMZL ET and EADS precipitation is robust.</p> / Dissertation

published_or_final_version / abstract / Civil Engineering / Master / Master of Philosophy

Chemical weathering reactions are important for the physical, chemical, and biological development of the critical zone. We present findings from aqueous phase chemical analyses of surface and soil pore waters during a 15 month study in a small semi-arid mountain catchment of the Santa Catalina Mountain Critical Zone Observatory. Stream water geochemical solutes are sourced to two distinct locations - fractured bedrock baseflow stores and soil quickflow stores. Solid phase observations of albite, anorthite, and K-feldspar transformation to Ca-montmorillonite and kaolinite are supported by stream water saturation states calculated via a PHREEQC geochemical model. While differences in mineral assemblages, soil depths, and horizonation suggest greater weathering in schist versus granite lithologies and in hillslope divergent versus convergent zones, soil pore water solute ratio analysis does not readily distinguish these differences. However, preliminary investigation of aqueous rare earth elements suggests detectable lithologic and landscape positional differences warranting focus for future research efforts.

114 pp. / Riparian areas occupy less than 2% of the arid Western United States. Their importance is disproportionate to the small area they occupy because of their multiple use applications. Riparian areas provide recreational amenities, habitat and travel corridors for wildlife, livestock grazing areas and influence water quality and quantity. In Arizona, as in many other states, there is a need to provide science-based educational publications to inform the public on riparian areas. In this publications the information will focus on: 1) the definition, importance and characterization of riparian areas 2) hydrologic, geomorphic, climatic, and biological processes in riparian areas, and 3) human alterations to riparian areas. This information is essential for land-managers and the general public to manage properly or restore healthy riparian areas.