Download or read book Assessing Hydrologic Impacts of Climate Change Over Semi arid Region Using Bias adjusted Dynamically Downscaled Meteorological Forcing written by Tsou Chun Jaw and published by . This book was released on 2011 with total page 168 pages. Available in PDF, EPUB and Kindle. Book excerpt: Twentieth century climate change induced by anthropogenic forcings has been recognized as one of the most serious issues affecting the development of mankind. Impacts of climate change on hydrologic processes are highly relevant to human activities and draw a great deal of scientific attention. In particular, semi-arid hydrology and water resources, which are encountering significant challenges in present climate, are projected to be more vulnerable to the future climate. While relevant studies emphasize large-scale impacts on hydrological processes due to climate changes, investigations of the impacts of climate changes on regional, even basin-scale hydrology are relatively limited. The main objective of this dissertation is to assess the potential hydrologic impacts of climate change over a semi-arid region by means of hydrologic modeling driven by high-resolution meteorological forcings. While GCMs are considered as powerful tools to simulate large-scale climate changes in the Earth system, climate information derived from GCMs needs to be further downscaled to meet the requirements of assessing the impact of regional climate and hydrology on global climate change. In this study, dynamical downscaling implementing a Regional Climate Model (RCM) to derive finer-resolution climate data is conducted, and three GCMs (BCCR, CCSM3, and ECHAM5) are adopted as the forcing data sets of the dynamical downscaling to evaluate regional climate and its hydrologic impacts over the semi-arid Morocco under the present-day and future climate scenarios. Downscaled precipitation analyses indicate that, systematically, biases are present. Directly using biased RCM output for hydrologic assessments would lead to unrealistic results. Therefore, effective bias correction approaches for the meteorological forcings required in the hydrologic modeling are adopted. While dynamically-downscaled GCMs show varying biases, downscaled ECHAM5 runs are more realistic in reproducing the historical climate patterns. Furthermore, proposed bias corrections (QM, EDCDF, and MovingCDF) significantly reduce the biases both in the meteorological forcings and their hydrologic responses. Among the correction approaches, MovingCDF accounts for the nonstationarity within the projection period and displays the best performance in forcing correction. Hydrologic simulation runs forced by the corrected forcings are significantly improved in the historical period in comparison with the results directly forced by RCM output. For future hydrologic assessments, hydrologic simulations driven by bias-corrected climate forcings exhibit a more consistent agreement. A drier hydrologic condition in the study region is expected in the near future (2036-2065). However, the degrees of the hydrologic impact, are highly dependent on the behaviors of large-scale GCM forcings.
Download or read book Assessing the Effects of Climate Change in a Semiarid Basin Utilizing a Fully Distributed Hydrologic Model written by Gretchen Hawkins and published by . This book was released on 2012 with total page 109 pages. Available in PDF, EPUB and Kindle. Book excerpt: The North American Monsoon (NAM) is characterized by high inter- and intra-seasonal variability, and potential climate change effects have been forecasted to increase this variability. The potential effects of climate change to the hydrology of the southwestern U.S. is of interest as they could have consequences to water resources, floods, and land management. I applied a distributed watershed model, the Triangulated Irregular Network (TIN)-based Real-time Integrated Basin Simulator (tRIBS), to the Beaver Creek basin in Arizona. This sub-basin of the Verde River is representative of the regional topography, land cover, and soils distribution. As such, it can serve to illustrate the utility of distributed models for change assessment studies. Model calibration was performed utilizing radar-based NEXRAD data, and comparisons were done to two additional sources of precipitation data: ground-based stations and the North American Land Data Assimilation System (NLDAS). Comparisons focus on the spatiotemporal distributions of precipitation and stream discharge. Utilizing the calibrated model, I applied scenarios from the HadCM3 General Circulation Model (GCM) which was dynamically downscaled by the Weather Research and Forecast (WRF) model, to refine the representation of Arizona's regional climate. Two time periods were examined, a historical 1990-2000 and a future 2031-2040, to evaluate the hydrologic consequence in the form of differences and similarities between the decadal averages for temperature, precipitation, stream discharge and evapotranspiration. Results indicate an increase in mean air temperature over the basin by 1.2 C. The average decadal precipitation amounts increased between the two time periods by 2.4 times that of the historical period and had an increase in variability that was 3 times the historical period. For the future period, modeled streamflow discharge in the summer increased by a factor of 3. There was no significant change in the average evapotranspiration (ET). Overall trends of increase precipitation and variability for future climate scenarios have a more significant effect on the hydrologic response than temperature increases in the system during NAM in this study basin. The results from this study suggest that water management in the Beaver Creek will need to adapt to higher summer streamflow amounts.
Download or read book Statistical Downscaling for Hydrological and Environmental Applications written by Taesam Lee and published by CRC Press. This book was released on 2018-09-03 with total page 163 pages. Available in PDF, EPUB and Kindle. Book excerpt: Global climate change is typically understood and modeled using global climate models (GCMs), but the outputs of these models in terms of hydrological variables are only available on coarse or large spatial and time scales, while finer spatial and temporal resolutions are needed to reliably assess the hydro-environmental impacts of climate change. To reliably obtain the required resolutions of hydrological variables, statistical downscaling is typically employed. Statistical Downscaling for Hydrological and Environmental Applications presents statistical downscaling techniques in a practical manner so that both students and practitioners can readily utilize them. Numerous methods are presented, and all are illustrated with practical examples. The book is written so that no prior background in statistics is needed, and it will be useful to graduate students, college faculty, and researchers in hydrology, hydroclimatology, agricultural and environmental sciences, and watershed management. It will also be of interest to environmental policymakers at the local, state, and national levels, as well as readers interested in climate change and its related hydrologic impacts. Features: Examines how to model hydrological events such as extreme rainfall, floods, and droughts at the local, watershed level. Explains how to properly correct for significant biases with the observational data normally found in current Global Climate Models (GCMs). Presents temporal downscaling from daily to hourly with a nonparametric approach. Discusses the myriad effects of climate change on hydrological processes.
Download or read book Impacts of Climate Change on Rainfall Extremes and Urban Drainage Systems written by Patrick Willems and published by IWA Publishing. This book was released on 2012-09-14 with total page 239 pages. Available in PDF, EPUB and Kindle. Book excerpt: Impacts of Climate Change on Rainfall Extremes and Urban Drainage Systems provides a state-of-the-art overview of existing methodologies and relevant results related to the assessment of the climate change impacts on urban rainfall extremes as well as on urban hydrology and hydraulics. This overview focuses mainly on several difficulties and limitations regarding the current methods and discusses various issues and challenges facing the research community in dealing with the climate change impact assessment and adaptation for urban drainage infrastructure design and management. Authors: Patrick Willems, University of Leuven, Hydraulics division; Jonas Olsson, Swedish Meteorological and Hydrological Institute; Karsten Arnbjerg-Nielsen, Technical University of Denmark, Department of Environmental Engineering; Simon Beecham, University of South Australia, School of Natural and Built Environments; Assela Pathirana, UNESCO-IHE Institute for Water Education; Ida Bulow Gregersen, Technical University of Denmark, Department of Environmental Engineering; Henrik Madsen, DHI Water & Environment, Water Resources Department; Van-Thanh-Van Nguyen, McGill University, Department of Civil Engineering and Applied Mechanics
Download or read book Seasonal Hydrologic Dynamics Under Changing Climate Land Use land Cover and Human Influence written by Namrata Batra and published by . This book was released on 2010 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Climatic changes along with the land use-land cover changes (LULCC) and human impacts significantly modify the hydrologic flow regime of the river basins, affecting water resources and environment from regional to global scale. Aided by satellite data, modeling and understanding of the interactions between physical and human systems, more reliable regional LULCC and climate change projections are now available. However, resulting quantitative projection of changes on the hydrologic components at the seasonal time scale are sparse. This study attempts to quantify the hydrologic response in different hydro-climatic regions of the world at the seasonal time scale in the context of the projected LULCC and climate change assessed through Intergovernmental Panel on Climate Change (IPCC) A1B emission scenario. The Common Land Model (CLM) is used as the hydrologic model for the study since it incorporates detailed physical process representation, uses physical parameterization without the need for calibration and can be run at relatively high spatial and temporal resolutions. A coupled modeling framework is applied to assess human water use impact on hydrologic discharge at the river basin scale by coupling of CLM to the Water Availability and Supply Model (WASM). A consistent global GIS based dataset is constructed for the Surface Boundary Conditions (SBCs) and meteorological forcing of the model. European Center for Medium Range Weather Forecasts (ECMWF) reanalysis data at 6-hour time step for the period 1976 through 2000 is used for meteorological forcing. The model results are validated using the observed discharge data from Global Runoff Distribution Center (GRDC). The ability of the hydrologic model to capture the dominant runoff processes at multiple time scales of interaction of the processes is explored using wavelet analysis. Future climate change projections are derived from the Fourth Assessment Report of IPCC based on the multi-model ensembles of projections. An Integrated Model to Assess the Global Environment (IMAGE), developed by the Netherlands Environmental Assessment Agency is used for LULCC data. The study is performed over nine river basins selected from Asia, Africa and North America to represent the broad climatic, landscape and human controls on the seasonal hydrological dynamics, and to assess how these controls differ for basins lying in different hydro-climatic regions. It is observed for all the study basins that small changes in the precipitation lead to much larger changes in the runoff response. The analysis reveals that certain regions (Orange and Volta basins in Africa) have seasons which are highly likely to experience significant reduction in future runoff while there are other regions (Ganges, Krishna and Huai basins in Asia) which have seasons very likely to experience increased runoff. These seasonal differences reflect the changes in water availability, which may not be known through annual estimates. Moreover, different aspects of human interferences are observed over each of the study basins. Comparison and quantification of such differences in the hydrologic components are of particular importance for the water resource managers and policy makers.
Download or read book Regional Hydrological Impacts of Climatic Change Impact assessment and decision making written by Thorsten Wagener and published by . This book was released on 2005 with total page 372 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Global Change and Extreme Hydrology written by National Research Council and published by National Academies Press. This book was released on 2011-11-17 with total page 44 pages. Available in PDF, EPUB and Kindle. Book excerpt: Climate theory dictates that core elements of the climate system, including precipitation, evapotranspiration, and reservoirs of atmospheric and soil moisture, should change as the climate warms, both in their means and extremes. A major challenge that faces the climate and hydrologic science communities is understanding the nature of these ongoing changes in climate and hydrology and the apparent anomalies that exist in reconciling their extreme manifestations. The National Research Council (NRC) Committee on Hydrologic Science (COHS) held a workshop on January 5-6, 2010, that examined how climate warming translates into hydrologic extremes like floods and droughts. The workshop brought together three groups of experts. The first two groups consisted of atmospheric scientists and hydrologists focused on the scientific underpinnings and empirical evidence linking climate variability to hydrologic extremes. The third group consisted of water managers and decision-makers charged with the design and operation of water systems that in the future must be made resilient in light of a changing climate and an environment of hydrologic extremes. Global Change and Extreme Hydrology summarizes the proceedings of this workshop. This report presents an overview of the current state of the science in terms of climate change and extreme hydrologic events. It examines the "conventional wisdom" that climate change will "accelerate" the hydrologic cycle, fuel more evaporation, and generate more precipitation, based on an increased capacity of a warmer atmosphere to hold more water vapor. The report also includes descriptions of the changes in frequency and severity of extremes, the ability (or inability) to model these changes, and the problem of communicating the best science to water resources practitioners in useful forums.
Download or read book Climate Change and Water Resources Management written by Levi D. Brekke and published by DIANE Publishing. This book was released on 2009-11 with total page 76 pages. Available in PDF, EPUB and Kindle. Book excerpt: Many challenges, including climate change, face the Nation¿s water managers. The Intergovernmental Panel on Climate Change (IPCC) has provided estimates of how climate may change, but more understanding of the processes driving the changes, the sequences of the changes, and the manifestation of these global changes at different scales could be beneficial. Since the changes will likely affect fundamental drivers of the hydrological cycle, climate change may have a large impact on water resources and water resources managers. The purpose of this interagency report is to explore strategies to improve water management by tracking, anticipating, and responding to climate change. Charts and tables.
Download or read book Regional Hydrological Impacts of Climatic Change Hydroclimatic variability written by Thorsten Wagener and published by . This book was released on 2005 with total page 318 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book A Case Study for Assessing the Hydrologic Impacts of Climate Change at the Watershed Scale written by Martinus Hubertus Brouwers and published by . This book was released on 2007 with total page 121 pages. Available in PDF, EPUB and Kindle. Book excerpt: Since the advent of the industrial era atmospheric concentrations of greenhouse gases have been on the rise leading to increasing global mean temperatures. Through increasing temperatures and changes to distributions of precipitation, climate change will intensify the hydrologic cycle which will directly impact surface water sources while the impacts to groundwater are reflected through changes in recharge to the water table. The IPCC (2001) reports that limited investigations have been conducted regarding the impacts of climate change to groundwater resources. The complexity of evaluating the hydrologic impacts of climate change requires the use of a numerical model. This thesis investigates the state of the science of conjunctive surface-subsurface water modeling with the aim of determining a suitable approach for conducting long-term transient simulations at the watershed scale. As a result of this investigation, a coupled modeling approach is adopted using HELP3 to simulate surface and vadose zone processes and HydroSphere to simulate saturated flow of groundwater. This approach is applied to the Alder Creek Watershed, which is a subwatershed of the Grand River Watershed and located near Kitchener-Waterloo, Ontario. The Alder Creek Watershed is a suitable case study for the evaluation of climate change scenarios as it has been well characterized from previous studies and it is relatively small in size. Two contrasting scenarios of climate change (i.e., drier and wetter futures) are evaluated relative to a reference scenario that is based on the historical climatic record of the region. The simulation results show a strong impact upon the timing of hydrologic processes, shifting the spring snow melt to earlier in the year leading to an overall decrease in runoff and increase in infiltration for both drier and wetter future climate scenarios. Both climate change scenarios showed a marked increase to overall evapotranspiration which is most pronounced in the summer months. The impacts to groundwater are more subdued relative to surface water. This is attributed to the climate forcing perturbations being attenuated by the shift of the spring snow melt and the transient storage effects of the vadose zone, which can be significant given the hummocky terrain of the region. The simulation results show a small overall rise of groundwater elevations resulting from the simulated increase in infiltration for both climate change scenarios.
Download or read book Watershed Scale Climate Change Projections for Use in Hydrologic Studies written by Muhammad Zia ur Rahman Hashmi and published by . This book was released on 2012 with total page 536 pages. Available in PDF, EPUB and Kindle. Book excerpt: Global Circulation Models (GCMs) are considered the most reliable source to provide the necessary data for climate change studies. At present, there is a wide variety of GCMs, which can be used for future projections of climate change using different emission scenarios. However, for assessing the hydrological impacts of climate change at the watershed and the regional scale, the GCM outputs cannot be used directly due to the mismatch in the spatial resolution between the GCMs and hydrological models. In order to use the output of a GCM for conducting hydrological impact studies, downscaling is used to convert the coarse spatial resolution of the GCM output into a fine resolution. In broad terms, downscaling techniques can be classified as dynamical downscaling and statistical downscaling. Statistical downscaling approaches are further classified into three broad categories, namely: (1) weather typing; (2) weather generators; and (3) multiple regression-based. For the assessment of hydrologic impacts of climate change at the watershed scale, statistical downscaling is usually preferred over dynamical downscaling as station scale information required for such studies may not be directly obtained through dynamical downscaling. Among the variables commonly downscaled, precipitation downscaling is still quite challenging, which has been recognised by many recent studies. Moreover, statistical downscaling methods are usually considered to be not very effective for simulation of precipitation, especially extreme precipitation events. On the other hand, the frequency and intensity of extreme precipitation events are very likely to be impacted by envisaged climate change in most parts of the world, thus posing the risk of increased floods and droughts. In this situation, hydrologists should only rely on those statistical downscaling tools that are equally efficient for simulating mean precipitation as well as extreme precipitation events. There is a wide variety of statistical downscaling methods available under the three categories mentioned above, and each method has its strengths and weaknesses. Therefore, no single method has been developed which is considered universal for all kinds of conditions and all variables. In this situation there is a need for multi-model downscaling studies to produce probabilistic climate change projections rather than a point estimate of a projected change. In order to address some of the key issues in the field of statistical downscaling research, this thesis study includes the evaluation of two well established and popular downscaling models, i.e. the Statistical DownScaling Model (SDSM) and Long Ashton Research Station Weather Generator (LARS-WG), in terms of their ability to downscale precipitation, with its mean and extreme characteristics, for the Clutha River watershed in New Zealand. It also presents the development of a novel statistical downscaling tool using Gene Expression Programming (GEP) and compares its performance with the SDSM-a widely used tool of similar nature. The GEP downscaling model proves to be a simpler and more efficient solution for precipitation downscaling than the SDSM model. Also, a major part of this study comprises of an evaluation of all the three downscaling models i.e. the SDSM, the LARS-WG and the GEP, in terms of their ability to simulate and downscale the frequency of extreme precipitation events, by fitting a Generalised Extreme Value (GEV) distribution to the annual maximum data obtained from the three models. Out of the three models, the GEP model appears to be the least efficient in simulating the frequency of extreme precipitation events while the other two models show reasonable capability in this regard. Furthermore, the research conducted for this thesis explores the development of a novel probabilistic multi-model ensemble of the three downscaling models, involved in the thesis study, using a Bayesian statistical framework and presents probabilistic projections of precipitation change for the Clutha watershed. In this way, the thesis endeavoured to contribute in the ongoing research related to statistical downscaling by addressing some of the key modern day issues highlighted by other leading researchers.
Download or read book A review of climate change scenarios and preliminary rainfall trend analysis in the Oum Er Rbia Basin Morocco written by Anne Chaponniere and published by IWMI. This book was released on 2006-06-02 with total page 23 pages. Available in PDF, EPUB and Kindle. Book excerpt: The paper reviews the existing tools methods and general literature which deal with the construction of climate change (CC) scenarios and with the assessment of impacts of these scenarios on water resources. It further examines the existing CC predictions specific to Morocco. The paper further describes the publicly available hydrometeorological time series data, which could be used to quantify the future CC scenarios for a river basin in Morocco (Oum er Rbia) and a smaller irrigation scheme within it (Tadla), located in the western part of the country. The data indicates that the impact of future CC on water resources at smaller scales such as smaller river basins, specific water resources and irrigation systems has to date not been properly addressed and, therefore, constitutes a niche for immediate research. This is, especially relevant in areas such as the Mediterranean region, which is predicted to be particularly affected by CC in the future. The preliminary trend analysis of available rainfall data suggests that the possible future CC impacts will decrease the precipitation in parts of the Atlas Mountains, which is the main source of water supply in western Morocco. The more recent data acquisition and the data from national sources in Morocco are necessary to further confirm/reject this hypothesis. The paper also discusses subsequent steps of the study of CC impacts on water resources in Oum er Rbia basin.
Download or read book The Regional Impacts of Climate Change written by Intergovernmental Panel on Climate Change. Working Group II. and published by Cambridge University Press. This book was released on 1998 with total page 532 pages. Available in PDF, EPUB and Kindle. Book excerpt: Cambridge, UK : Cambridge University Press, 1998.
Download or read book Evaluation of Climate Change Impact on Stream Flow written by Andualem Shimeles and published by LAP Lambert Academic Publishing. This book was released on 2013 with total page 104 pages. Available in PDF, EPUB and Kindle. Book excerpt: To assess how stream flow in Gilgel Abbay River Basin will be affected by climate change, the HadCM3 model, developed at the Hadley Centre in the United Kingdom, was used to generate medium-high and medium-low emission scenarios in this study. The statistical downscaling model was used to generate future possible local meteorological variables in the study area. The down-scaled data were then used as input to the Soil and Water Assessment Tool hydrological model to simulate the corresponding future stream flow regime in Gilgel Abbay River Basin. Three benchmark periods simulated were 2011-2040 (2020s), 2041-2070 (2050s), and 2071-2099 (2080s). The time series generated by HadCM3 and statistical downscaling method indicate a significant increasing trend in both maximum and minimum temperature values, and a decreasing trend in precipitation. The hydrologic impact analysis made with the downscaled temperature and precipitation time series as input to the SWAT model suggested an overall decreasing trend in annual and monthly stream flow in the study area, in three benchmark periods in the future. This should be considered by policymakers of water resources planning and management.
Download or read book Climate Change Assessment for the Southeastern United States written by Feng Zhang and published by . This book was released on 2011 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Water resource planning and management practices in the southeastern United States may be vulnerable to climate change. This vulnerability has not been quantified, and decision makers, although generally concerned, are unable to appreciate the extent of the possible impact of climate change nor formulate and adopt mitigating management strategies. Thus, this dissertation aims to fulfill this need by generating decision worthy data and information using an integrated climate change assessment framework.\r : To begin this work, we develop a new joint variable spatial downscaling technique for statistically downscaling gridded climatic variables to generate high-resolution, gridded datasets for regional watershed modeling and assessment. The approach differs from previous statistical downscaling methods in that multiple climatic variables are downscaled simultaneously and consistently to produce realistic climate projections. In the bias correction step, JVSD uses a differencing process to create stationary joint cumulative frequency statistics of the variables being downscaled. The functional relationship between these statistics and those of the historical observation period is subsequently used to remove GCM bias. The original variables are recovered through summation of bias corrected differenced sequences. In the spatial disaggregation step, JVSD uses a historical analogue approach, with historical analogues identified simultaneously for all atmospheric fields and over all areas of the basin under study. \r : In the second component of the integrated assessment framework, we develop a data-driven, downward hydrological watershed model for transforming the climate variables obtained from the downscaling procedures to hydrological variables. The watershed model includes several water balance elements with nonlinear storage-release functions. The release functions and parameters are data driven and estimated using a recursive identification methodology suitable for multiple, inter-linked modeling components. The model evolves from larger spatial/temporal scales down to smaller spatial/temporal scales with increasing model structure complexity. For ungauged or poorly-gauged watersheds, we developed and applied regionalization hydrologic models based on stepwise regressions to relate the parameters of the hydrological models to observed watershed responses at specific scales. \r : Finally, we present the climate change assessment results for six river basins in the southeastern United States. The historical (baseline) assessment is based on climatic data for the period 1901 through 2009. The future assessment consists of running the assessment models under all IPCC A1B and A2 climate scenarios for the period from 2000 through 2099. The climate assessment includes temperature, precipitation, and potential evapotranspiration; the hydrology assessment includes primary hydrologic variables (i.e., soil moisture, evapotranspiration, and runoff) for each watershed.
Download or read book Climate Variability and Change written by Flow Regimes from International Experimental and Network Data (Project) and published by . This book was released on 2006 with total page 738 pages. Available in PDF, EPUB and Kindle. Book excerpt: This volume contains 117 reviewed papers from over 30 countries, published in English, French and Spanish, which reflect both international dimension of FRIEND and the key challenges facing hydrologists in the 21st century.
Download or read book Climate Change 2021 The Physical Science Basis written by Intergovernmental Panel on Climate Change (IPCC) and published by Cambridge University Press. This book was released on 2023-07-26 with total page 2410 pages. Available in PDF, EPUB and Kindle. Book excerpt: The Working Group I contribution to the Sixth Assessment Report of the Intergovernmental Panel on Climate Change (IPCC) provides a comprehensive assessment of the physical science basis of climate change. It considers in situ and remote observations; paleoclimate information; understanding of climate drivers and physical, chemical, and biological processes and feedbacks; global and regional climate modelling; advances in methods of analyses; and insights from climate services. It assesses the current state of the climate; human influence on climate in all regions; future climate change including sea level rise; global warming effects including extremes; climate information for risk assessment and regional adaptation; limiting climate change by reaching net zero carbon dioxide emissions and reducing other greenhouse gas emissions; and benefits for air quality. The report serves policymakers, decision makers, stakeholders, and all interested parties with the latest policy-relevant information on climate change. Available as Open Access on Cambridge Core.
