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Modeling of watershed response to normal and extreme climatic conditions or to changes in the physical conditions of a watershed requires the simulation of a variety of complex hydrologic processes and process interactions. Some of these processes are well understood at a point or for a small area; others are poorly understood at all scales. Increasing spatial and temporal variability in climate and watershed characteristics with an increase in watershed area adds significantly to the degree of difficulty in investigating and understanding these processes. Research is needed to better define these processes and to develop techniques to simulate these processes and their interactions at all watershed scales. Project...
1) Improve predictions of streamflow at ungaged basins, and 2) understanding the causes of streamflow changes due to human changes to the environment, and 3) establish biological-flow relations.
Understanding the effects of climatic variability is important to development of water resources, mitigation of flood hazards, and interpretation of geomorphic surfaces. Climatic variability, which is characterized by temporal changes in variability of seasonal climate that spans decades or centuries, may be more important to water-resources evaluations than changes in mean climatic conditions. Changes in variability of climate has a large effect on the probability of occurrence of extreme events, such as floods or droughts. Understanding of climatic variability and its effect on the landscape is of paramount importance for estimation of flood frequency, sediment transport rates, and long-term watershed and channel...
Using long-term data records, this project is focused on two problems of importance to water resources managers. First, long-term streamflow records are being used to a) identify broad regional to national trends in floods and low-flows and relate them to possible causes (climate change, water management changes, land-cover changes, and ground-water level change) and b) determine whether there are patterns that relate to watershed size or climate characteristics. It is often stated in the popular press and in official publications on global climate change that we can expect increased variability, including larger and/or more frequent floods, and deeper and longer droughts, as a result of greenhouse warming. This...
The objectives of my research are (1) to synthesize observational estimates of continental water and energy fluxes and storage; (2) to construct global computational models of continental water and energy fluxes and storage; (3) to identify physical controls, natural and anthropogenic, on spatial and temporal variability of water and energy fluxes and storage; and (4) to elucidate the hydrologic causes and effects of Earth-system variability and change, including climatic, biospheric, and geodetic processes.
The overall objective of the MoWS research group is to gain better understanding of the precipitation-runoff processes and use this knowledge to develop improved hydrologic models. The main research topics include: 1) Add functionality and improvements to the MoWS simulation models being developed and integrate with other hydrologic, hydraulic, and climate models. 2) Enhance the models to use the best and latest topographic, climate, geologic, and land-use data sets as direct input to process algorithms to increase the physical nature and temporal and spatial resolution of model input. 3) Develop national model structure and calibration strategy for national model application.
Climate displays an often-unrecognized order in both time and space. What may appear as a random sequence of precipitation at a point or within a watershed is actually the local expression of a broad integrated system of weather processes that are active on scales of 100’s to 1000’s of kilometers. Only when climate forcings and hydrologic responses are considered from a regional perspective does the order become evident. Understanding these regional processes provides a sound basis for national, regional, and local hydrologic analysis, resource management, and hazard assessment/mitigation. The objectives of this research are (1) to identify and quantify relations between large-scale atmospheric circulation and sea-surface...
Research Objectives: To better understand the response of watershed hydrology, freshwater management and estuaries to climate variability and change. In the estuarine component of this research, there is an emphasis on the responses of physical processes that drive ecological variability and change.
To better understand climate variability and possible climate change effects on surface hydrology, water resources and related natural and human managed systems in the western U.S., with emphasis on California.
To better understand and predict variability and recent changes in the responses of rivers, groundwater, and water/living resources, mostly in the West, to natural and human-induced climatic influences.
An important challenge of the 21st century is the global water challenge that is exacerbated by recent droughts and rapid population growth. Water shortages have led to increased reliance on groundwater and broad reductions in groundwater resources. As demands for water resources increase, our understanding of interconnections between the hydrologic cycle and our environment increasingly become more important. Moving into the future, approaches are needed for sustainable management of water resources in order to maintain robust water-dependent systems on earth. Our research aims to better understand local and regional hydrologic processes affecting humans and the environment. Our focus is on the development of...
Understanding the effects of climatic variability is important to development of water resources, mitigation of flood hazards, and interpretation of geomorphic surfaces. Climatic variability, which is characterized by temporal changes in variability of seasonal climate that spans decades or centuries, may be more important to water-resources evaluations than changes in mean climatic conditions. Changes in variability of climate has a large effect on the probability of occurrence of extreme events, such as floods or droughts. Understanding of climatic variability and its effect on the landscape is of paramount importance for estimation of flood frequency, sediment transport rates, and long-term watershed and channel...
The overall objective of the MoWS research group is to gain better understanding of the precipitation-runoff processes and use this knowledge to develop improved hydrologic models. The main research topics include: 1) Add functionality and improvements to the MoWS simulation models being developed and integrate with other hydrologic, hydraulic, and climate models. 2) Enhance the models to use the best and latest topographic, climate, geologic, and land-use data sets as direct input to process algorithms to increase the physical nature and temporal and spatial resolution of model input. 3) Develop national model structure and calibration strategy for national model application.
To anticipate the effects of potential climate change (natural or anthropogenic) on hydrology and to assess hydrologic trends will require an understanding of past long-term hydrologic variability. There also is a critical need for data on extreme floods for better understanding flood processes, in engineering hydrology, flood-hazard mitigation, and other disciplines requiring flood-risk assessments. Probably the best information on hydrologic variability and extreme floods is provided by paleohydrologic and other proxy data analyzed with the help of hydrologic models. Methods for extending existing climatic and hydrologic records over long-time scales are needed. A relatively new approach, one that complements...
The regional nature of hydrologic processes is generally defined in terms of shared meteorological and basin characteristics. Inferences have been attempted by regressing the parameters of hydrologic interest against these characteristics. Such analyses have not been able to fully explain the variations, extremes or persistence of discharge patterns observed within a geographic area. An accounting of anthropogenic effects on basin characteristics needs to be made. Longer term influences such as decadal to centennial, and millennial climatic fluctuations need to be considered, and the stochastic structure of the hydrologic process itself needs to be studied. The objectives of this project are (1.) to develop secular...
Biotic responses to climatic change or human manipulation are inherently complex because of wide differences in organism sensitivities and response times, the influence of history and scale, and the various interactions between organisms and with the physical system. In arid and semi-arid lands, which cover about 12.5 percent of the Earth's land surface, the effects of climatic variability on vegetation are greatly magnified, particularly because most plants exist near their physiological limits. How arid land vegetation might in turn affect climate is uncertain, though there is some indication that decreasing cover and increasing albedo could promote regional drought. Whether in response to projected Greenhouse...
The Tropical and Arid Regions Climate Project seeks to quantify past variations in climate and the hydrologic balance through studies of paleo and modern surface- and ground-water systems using stable isotope and other chemical methodologies. Objectives of the Tropical and Arid Regions Climate Projects are to determine: (1) the frequency and severity of drought during the past 10,000 years, (2) the frequency and severity of major cooling events that led to glacial advances in the Colorado Rockies, (3) the frequency of hurricanes that impacted the Carribbean and Gulf of Mexico over the past 400 years, and (4) the impact of climate change on prehistoric Native Americans.