Thesis (M.Sc.). / Written for the Dept. of Bioresource Engineering. Title from title page of PDF (viewed 2008/05/14). Includes bibliographical references.

Thesis (M.S.)--Rutgers University, 2007. / "Graduate Program in Geological Sciences." Includes bibliographical references (p. 79-83).

Climate change has posed significant challenges for the world's sustainable development, and the water cycle is highly dependent on the climate system. In particular, the arid zone fragile ecosystems in northwest China are highly vulnerable to the sophisticated hydrological variations. While ground-based measurements are less capable for large scale hydrological modelling, remote sensing techniques offer enhanced and effective alternatives for various hydrological states/fluxes. With the advancement of the Gravity Recovery and Climate Experiment (GRACE) satellites, the Terrestrial Water Storage (TWS), an integrative measurement of regional hydro-climatic environment, can now be measured as well for examining the overall hydrological response to recent climate change. TWS is an essential element of the water cycle and a key state variable for land surface-atmosphere interaction. Investigating the TWS change is important for understanding the response of the water cycle to climate change. In this study, the intra-annual and inter-annual spatio-temporal change pattern of TWS in Xinjiang Uyghur Autonomous Region of China during 2003-2015 are characterized from Gravity Recovery and Climate Experiment (GRACE) Tellus data products. Sub-regional re-analysis reveals that the increasing/decreasing rate in sub-regions, namely, Altay Mountains (ATM), Junggar Basin (JGB), Tianshan Mountains (TSM), Tarim Basin (TRB) and Kunlun Mountains (KLM), are - 3.41mm, -5.82mm, -6.76mm, -2.59mm and +3.05mm per year in unit of equivalent water height (EWH), respectively. The results suggest that TWS variation presents certain spatio-temporal patterns with spatial heterogeneity. The uncertainties from different GRACE products are also assessed. In conjunction with gridded meteorological data products and land surface model simulations of hydrological variables, the heterogeneous mechanisms of seasonal TWS change are analyzed. The correlation relationship among various hydrologic states/fluxes variables (e.g. snow water, soil water, snow amount) and climatic variables (e.g. temperature and precipitation) with GRACE-derived TWS variation in different sub-regions are investigated. The findings appear to indicate that 1) temperature month-over-month change and temperature anomaly with 4- month time lag, rather than precipitation, are more capable to explain the intra- annual TWS variation; 2) In most part of the study area, the TWS intra-annual change can be primarily attributed to the snow accumulation in winter and melt in spring. On the other hand, the glacier mass variation, which is particularly sensitive to recent climate change, could be a substantial contributor to inter-annual TWS change. The elevation trends over glaciers are estimated based on ICESat altimetry measurements. Correlation analysis results suggest that, during 2003- 2009, the inter-annual TWS loss in Tianshan Mountains (TSM) was tightly associated with glacier mass variation induced by temperature change, particularly in summer. In contrast, TWS gain in Kunlun Mountains (KLM) can be attributed to glacier mass increase. By utilizing remote sensing observation techniques/products, this study has characterized the spatio-temporal change pattern of TWS in northwest arid zone of China, as well as the underlying mechanism. It suggests that TWS is an effective indicator of regional climate change. This study contributes to a better understanding of the hydrologic and climatic processes in arid zone water cycle, and could be beneficial for regional water resources management and climate change adaptation effort.

Made available in DSpace on 2014-06-11T19:26:47Z (GMT). No. of bitstreams: 0 Previous issue date: 2011-04-18Bitstream added on 2014-06-13T19:34:37Z : No. of bitstreams: 1 silva_rfb_me_botfca.pdf: 1032918 bytes, checksum: fee4c4cfa450d8a450079bb3d387d04b (MD5) / Universidade Estadual Paulista (UNESP) / O objetivo deste trabalho foi construir um banco de dados digital do meio físico e desenvolver uma metodologia para a definição das áreas hidrologicamente importantes no ciclo hidrológico em uma sub-bacia hidrográfica, visando à priorização destas áreas em planos de recuperação de áreas degradadas, compensações florestais ou uso sustentado por meio de práticas de manejo conservacionistas. A sub-bacia hidrográfica pesquisada, localizada no interior do estado de São Paulo, estende-se sobre o Reverso da Cuesta, atravessando o Front e com sua foz na Depressão Periférica, no Rio Tietê. A cobertura do solo predominante é a cana-de-açúcar - 38% (10423 ha). O levantamento de solos em nível semidetalhado identificou uma série de comportamentos expressos através de diferentes tipos de solos relacionados com declividade, proximidade ao Front da Cuesta, rede de drenagem ou mesmo à Depressão Periférica onde a rocha originária são os arenitos Botucatu e Pirambóia ou ao Reverso da Cuesta onde a rocha originária é o arenito Marília. O uso do Geoprocessamento permitiu equacionar um volume de informações em velocidade e precisão que a mente humana não seria capaz de processar em igual desempenho. A partir dos resultados da pesquisa, pôde-se concluir que: o desenvolvimento de um mapa semidetalhado de solos foi fundamental para a obtenção de informações sobre os comportamentos das diferentes unidades pedológicas da subbacia frente às respostas na sua interação com a água / The objective of the Project was build a digital data base of the physical environment and develop a methodology to the definition of sensible areas for the hydrological process on a watershed, allocation these areas for environmental restoration planning, forestry practices and sustainable use by conservations practices of the management. The watershed is located at the country of Sao Paulo State and spread out above the Reverse of the Cuesta, crossing the Front reaching your river mouth in the Periferic Depression, at Tietê River. The predominant land cover is sugar cane – 38% (10423 ha). The soil survey at the semidetailed level has been identified a number os behaviors expressed by the different kinds of soil and their relationships with slope, proximity of the Front, water drainage and even Periferic Depression where the original rock is Botucatu sandstone, and in the Reverse is the Marília sandstone. The Geoprocessing approach allowed to equate an amount of geoinformations with a high speed and precision that would be impossible by the human mind in equal performance. In according with the results of the research, could be conclude that: the developing of the semidetailed soil map was fundamental for the informations about the behaviors of the soil units in their interactions with water

Orientador: Célia Regina Lopes Zimback / Banca: Sérgio Lazaro de Lima / Banca: Silvio Frosini de Barros Ferraz / Resumo: O objetivo deste trabalho foi construir um banco de dados digital do meio físico e desenvolver uma metodologia para a definição das áreas hidrologicamente importantes no ciclo hidrológico em uma sub-bacia hidrográfica, visando à priorização destas áreas em planos de recuperação de áreas degradadas, compensações florestais ou uso sustentado por meio de práticas de manejo conservacionistas. A sub-bacia hidrográfica pesquisada, localizada no interior do estado de São Paulo, estende-se sobre o Reverso da Cuesta, atravessando o Front e com sua foz na Depressão Periférica, no Rio Tietê. A cobertura do solo predominante é a cana-de-açúcar - 38% (10423 ha). O levantamento de solos em nível semidetalhado identificou uma série de comportamentos expressos através de diferentes tipos de solos relacionados com declividade, proximidade ao Front da Cuesta, rede de drenagem ou mesmo à Depressão Periférica onde a rocha originária são os arenitos Botucatu e Pirambóia ou ao Reverso da Cuesta onde a rocha originária é o arenito Marília. O uso do Geoprocessamento permitiu equacionar um volume de informações em velocidade e precisão que a mente humana não seria capaz de processar em igual desempenho. A partir dos resultados da pesquisa, pôde-se concluir que: o desenvolvimento de um mapa semidetalhado de solos foi fundamental para a obtenção de informações sobre os comportamentos das diferentes unidades pedológicas da subbacia frente às respostas na sua interação com a água / Abstract: The objective of the Project was build a digital data base of the physical environment and develop a methodology to the definition of sensible areas for the hydrological process on a watershed, allocation these areas for environmental restoration planning, forestry practices and sustainable use by conservations practices of the management. The watershed is located at the country of Sao Paulo State and spread out above the Reverse of the Cuesta, crossing the Front reaching your river mouth in the Periferic Depression, at Tietê River. The predominant land cover is sugar cane - 38% (10423 ha). The soil survey at the semidetailed level has been identified a number os behaviors expressed by the different kinds of soil and their relationships with slope, proximity of the Front, water drainage and even Periferic Depression where the original rock is Botucatu sandstone, and in the Reverse is the Marília sandstone. The Geoprocessing approach allowed to equate an amount of geoinformations with a high speed and precision that would be impossible by the human mind in equal performance. In according with the results of the research, could be conclude that: the developing of the semidetailed soil map was fundamental for the informations about the behaviors of the soil units in their interactions with water / Mestre

Predicting how increasing atmospheric carbon dioxide concentration will affect the hydrologic cycle is of utmost importance for water resource management, ecological systems and for human life and activities. A typical perspective is that the water cycle will mostly be altered by atmospheric effects of climate change, precipitation and radiation, and that the land surface will adjust accordingly. Terrestrial processes can however feedback significantly on the hydrologic changes themselves. Vegetation is indeed at the center of the carbon, water and energy nexus. This work investigates the processes, the timing and the geography of these feedbacks. Using Earth System Models simulations from the Coupled Model Intercomparison Project, Phase 5 (CMIP5), with decoupled surface (vegetation physiology) and atmospheric (radiative) responses to increased atmospheric carbon dioxide concentration, we first evaluate the individual contribution of precipitation, radiation and physiological forcings for several key hydrological variables. Over the largest fraction of the globe the physiological response indeed not only impacts, but also dominates the change in the continental hydrologic cycle compared to either radiative or precipitation changes due to increased atmospheric carbon dioxide concentration. It is however complicated to draw any conclusion for the soil moisture as it exhibits a particularly nonlinear response. The physiological feedbacks are especially important for extreme temperature events. The 2003 European heat wave is an interesting and crucial case study, as extreme heat waves are anticipated to become more frequent and more severe with increasing atmospheric carbon dioxide concentration. The soil moisture and land-atmosphere feedbacks were responsible for the severity of this episode unique for this region. Instead of focusing on statistical change, we use the framework of Regional Climate Modeling to simulate this specific event under higher levels of surface atmospheric carbon dioxide concentration and to assess how this heat wave could be altered by land-atmosphere interactions in the future. Increased atmospheric carbon dioxide concentration modifies the seasonality of the water cycle through stomatal regulation and increased leaf area. As a result, the water saved during the growing season through higher water use efficiency mitigates summer dryness and the heat wave impact. Land-atmosphere interactions and carbon dioxide fertilization together synergistically contribute to increased summer transpiration if rainfall does not change. This, in turn, alters the surface energy budget and decreases sensible heat flux, mitigating air temperature rise during extreme heat periods. This soil moisture feedback, which is mediated and enabled by the vegetation on a seasonal scale is a European example of the impacts the vegetation could have in an atmosphere enriched in carbon dioxide. We again use Earth System Models to systematically and statistically investigate the influence of the vegetation feedbacks on the global and regional changes of extreme temperatures. Physiological effects typically contribute to the increase of the annual daily maximum temperature with increasing atmospheric carbon dioxide concentration, accounting for around 15% of the full trend by the end of the XXIth Century. Except in Northern latitudes, the annual daily maximum temperature increases at a faster pace than the mean temperature, which is reinforced by vegetation feedbacks in Europe but reduced in North America. This work highlights the key role of vegetation in influencing future terrestrial hydrologic responses. Accurate representation of the response to higher atmospheric carbon dioxide concentration levels, and of the coupling between the carbon and water cycles are therefore critical to forecasting seasonal climate, water cycle dynamics and to enhance the accuracy of extreme event prediction under future climates in various regions of the globe.

The global continental carbon and water cycles are intimately linked through stomatal regulation during vegetation photosynthesis and biosphere-atmosphere interactions. Therefore, to have a complete understanding of both present and future climate, these cycles must be studied as an interconnected system. This thesis presents three studies that aim to better explain these interactions and provide a direction forward for improved model projections of climate. The first study shows that biosphere-atmosphere feedbacks can contribute up to 30% of climate and weather variability in certain regions that help determine the net CO2 balance of the biosphere. It demonstrates that Earth System Models are under-estimating these contributions, mainly due to the underestimation of the biosphere response to radiation and water availability. It emphasizes the importance of correctly capturing these feedbacks in models for accurate subseasonal to seasonal climate predictions. The second demonstrates that changes in soil moisture (both short-term variability and long-term trends) strongly limit the ability of the continents to act as a carbon sink, with overall effects on the same order of magnitude as the land sink itself. Photosynthesis rates tend to be reduced when soil moisture is depleted, leading to decreased carbon uptake. Additionally, respiration rates increase due to increased temperature through land-atmosphere feedbacks. These carbon losses are not compensated for during wet anomalies due to the nonlinear response of vegetation activity (both respiration and photosynthesis) to soil moisture. This suggests that the increasing trend in carbon uptake rate may not be sustained past the middle of the century and could result in accelerated atmospheric CO2 growth. The third decouples the effects of atmospheric dryness (vapor pressure deficit) and soil dryness on vegetation activity in the largest terrestrial carbon sink: the tropics. Understanding vegetation response to environmental drivers and stressors in the tropics is essential to accurately modeling these ecosystems and predicting whether they will remain carbon sinks in the future. The study finds that in regions that are water limited, vegetation is driven by precipitation and radiation while being limited by high vapor pressure deficit. Conversely, in the wettest regions that are light limited, increases in vapor pressure deficit accompany increasing rates of photosynthesis. These three studies contribute to our understanding of land-atmosphere and biosphere-atmosphere feedbacks and the coupling of the continental carbon and water cycles. They identify model process representations, such as soil moisture and vegetation water-stress, that are hindering our ability to make accurate forecasts. By improving our knowledge of these mechanisms and evaluating the ability of models to reproduce them, we pave the way forward for improved climate and weather projections. Better predictions can be used not only to protect society in the present, but also to appropriately shape climate policy to protect society in the future.

[Truncated abstract] Generally hydrologic and ecologic models operate on arbitrary time and space scales, selected by the model developer or user based on the availability of field data. In reality rainfall is highly variable not only annually, seasonally and monthly but also the intensities within a rainfall event and infiltration properties on semi-arid hillslopes can also be highly variable as a result of discontinuous vegetation cover that form mosaics of areas with vegetation and areas of bare soil. This thesis is directed at improving our understanding of the impacts of the temporal representation of rainfall and spatial heterogeneity on model predictions of hydrologic thresholds and surface runoff coefficients on semi-arid landscapes at the point and hillslope scales. We firstly quantified within storm rainfall variability across a climate gradient in Western Australia by parameterizing the bounded random cascade rainfall model with one minute rainfall from 15 locations across Western Australia. This study revealed that rainfall activity generated in the tropics had more within storm variability and a larger proportion of the storm events received the majority of rain in the first half of the event. Rainfall generated from fontal activity in the south was less variable and more evenly distributed throughout the event. Parameters from the rainfall analysis were then used as inputs into a conceptual point scale surface runoff model to investigate the sensitivity of point scale surface runoff thresholds to the resolution of rainfall inputs. This study related maximum infiltration capacities to average storm intensities (k*) and showed where model predictions of infiltration excess were most sensitive to rainfall resolution (ln k* = 0.4) and where using time averaged rainfall data can lead to an under prediction of infiltration excess and an over prediction of the amount of water entering the soil (ln k* > 2). For soils susceptible to both infiltration excess and saturation excess, total runoff sensitivity was scaled by relating drainage coefficients to average storm intensities (g*) and parameter ranges where predicted runoff was dominated by infiltration excess or saturation excess depending on the resolution of rainfall data were determined (ln g* <2). The sensitivity of surface runoff predictions and the influence of specific within storm properties were then analysed on the hillslope scale. '...' It was found that using the flow model we still get threshold behaviour in surface runoff. Where conditions produce slow surface runoff velocities, spatial heterogeneity and temporal heterogeneity influences hillslope surface runoff amounts. Where conditions create higher surface runoff velocities, the temporal structure of within storm intensities has a larger influence on runoff amounts than spatial heterogeneity. Our results show that a general understanding of the prevailing rainfall conditions and the soil's infiltration capacity can help in deciding whether high rainfall resolutions (below 1 h) are required for accurate surface runoff predictions. The results of this study can be considered a contribution to understanding the way within storm properties effect the processes on the hillslope under a range of overall storm, slope and infiltration conditions as well as an improved understanding of how different vegetation patterns function to trap runoff at different total vegetation covers and rainfall intensities.

Using ERA40 and independent observations, I assess how well Amazon surface water budget is estimated. ERA40 basin wide annual precipitation (P) agrees with observations showing an underestimation of 10%, whereas runoff (R) is underestimated by a larger margin (~25%). Observed residual of precipitation and runoff (P-R) is better estimated by ERA40 P-R than actual ET which includes soil moisture nudging. Nudging is necessary during the dry season to produce realistic ET and compensate for low soil moisture recharge during the wet season. Insufficient recharge may be caused by: underestimation of rainfall amount and intensity; a shallow root layer in the model that does not represent the deep soil water reservoir of the Amazonian forest. The physical links between changes in wet season onset and synoptic scale systems are investigated in the second part of my work. A delayed wet season onset is consistent with a decreasing number of cold air incursion (CAI) days in southern Amazon during 1979-2001. CAI variability in southern Amazon is related to SST in the tropical Pacific and Indian Oceans. The first mode of co-variability shows that during El Nio (La Nia) a strong (weak) subtropical jet stream over South America is related to decreased (increased) CAI days during SON. The second mode shows warm western Indian Ocean also related to strong subtropical jet stream. The absence a well defined subpolar jet stream, favors the northward displacement of transient waves into central South America, but shows little response in southern Amazon. CAI days reconstructed from the first and second modes do not present any significant trend in southern Amazon. CAI days reconstructed from the third mode of co-variability reproduces SON observed trend. This mode describes negative (positive) anomalies in CAI days associated with cold (warm) SST anomalies, anomalous wavetrain in the tropical Pacific and Walker Cell displacement that are unfavorable (favorable) to the incursion of CAI into southern Amazon. This mode's temporal evolution correlates with the Pacific Decadal Oscillation (PDO), suggesting that its recent gradual signal shift reflected on the interannual response of southern Pacific atmospheric patterns, hence on the behavior of transients propagation.

Thesis (Ph.D.)--McMaster University (Canada), 1996. / Source: Dissertation Abstracts International, Volume: 57-10, Section: B, page: 6146. Adviser: M. K. Woo.