Skip to main content
Advanced Search

Filters: Tags: Geomorphology and Sediment Transport (X)

14 results (150ms)   

View Results as: JSON ATOM CSV
My research focuses on the application of remote sensing to rivers as a means of more efficiently characterizing fluvial systems, primarily channel form and behavior. More specifically, I develop, test, and apply methods of measuring various river attributes, such as depth, streambed composition, turbidity, and flow velocity, from different types of remotely sensed data, including multi- and hyperspectral images and near-infrared and green LiDAR. These techniques provide higher resolution, essentially continuous data over larger spatial extents than could be surveyed via conventional field methods and thus could facilitate river research and management. My research involves a combination of numerical radiative...
To provide useful tools in river hydraulics, sediment transport, and geomorphology that: can be used to predict the impacts of man’s activities in rivers, canals, and reservoirs; can forecast the natural evolution of fluvial courses of water; provide analytic and computational platforms to study hypothesis; and enhance our understanding of fluvial morphodynamics.
Many difficult problems in river mechanics may have stemmed from inadequate understanding of the multiplicity and interaction of fluvial processes. Some of the problems may have been solved, but in a very simplified, approximate way. Many efforts have been directed, but without apparent success, to fully account for the causes, occurrences, and mechanisms of catastrophic events, such as flash floods, debris flows, and channel changes resulting from torrential storms, sudden snow or glacier melt, dam break, volcanic eruptions, and earthquakes. Such failures may be partially attributed to the deficiency and incompleteness of existing empirical formulas (or models) representing the relationships between various processes...
Predicting the outcome of flow and sediment transport events quantitatively has been difficult due to the complex nature of stream systems and the effects of woody vegetation on flow and sediment transport. Interactions between channel and floodplain flow, sediment transport, and woody vegetation have important implications for the health of riparian vegetation and as well as for contaminant transport and deposition. The goal of my research is to develop methods for the application and testing of predictive, process-based models (no empirically adjusted coefficients) that compute the flow and sediment transport from fluid mechanical theory for (1) known channel and floodplain topography and (2) measured tree and...
Project research is focused on two general objectives: first, to better understand the basic physics of coupled flow and sediment transport in geophysical flows; second, to develop practical tools based on that understanding that can be used in a predictive manner to aid in the management of the Nation’s rivers. Within the context of this overarching pair of long-term goals, the project has a number of specific shorter-term objectives, some of which are research oriented, and others of which are related to technology transfer or consultation on specific riverine issues. Our current research objectives are as follows: 1) Develop and test physically based methods for predicting the initiation, development, and response...
Sediment moves through a river system in response to specific events and changing conditions in the drainage basin. The movement of sediment is usually discontinuous. Episodes of movement are separated by periods of storage that can range from less than a year to more than one thousand. Understanding the movement and storage of sediment in rivers is important to navigation, flood control, and other aspects of river engineering, as well as to the prediction of the fate of contaminants adsorbed on sediment particles. This project's objectives are to assess: (1) changes in river sediment loads over periods of decades or longer, and the factors (natural or artificial) that cause the changes; (2) rates at which sediment...
The geometry and pattern of river channels adjust to significant changes in the water discharge, size, and quantity of sediment supplied to the channel. When the quantity of water and sediment over a period of years remains relatively constant, the channel geometry and pattern vary about a mean of quasi-equilibrium conditions. Major watershed alterations that change the supply of water, sediment, and size of sediment reaching the channel necessitate an adjustment of the channel geometry and pattern. That is, the channel is transformed from one quasi-equilibrium state to another. Between the two quasi-equilibrium states, there is a period of instability and adjustment. The dynamics and rate of river channel adjustment...
This project focuses on sediment erosion and deposition processes associated with disturbed watersheds and the essential processes needed to predict evolution of river systems. The objectives are to understand: a. Spatial and temporal character of rainfall and the transformation of rainfall into runoff, which controls erosion and deposition. b. Hillslope runoff processes characterized by shallow, unsteady flow where the relative roughness causing friction can be much greater than, for example, in perennial channels with nearly steady flow. c. Geomorphic and scale effects of channel networks on the prediction of the runoff hydrographs. d. Coupling of biologic and geomorphologic processes to predict erosion and...
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...
Stream systems function as integrated units from the zero-order basins at their heads to their terminations at the sea. Interior adjustments to changes in their headwaters or along their lengths occur in a variety of ways, some of which leave sedimentary deposits that provide important information with regard to the sensitivity of the systems to disturbances of various magnitudes and with respect to the nature of past disturbances. The former type of information is crucial to reliable interpretation of paleoflood deposits and the latter knowledge is essential for testing hydrologic predictions derived from climate models. In order to interpret fluvial deposits properly, however, an extremely accurate knowledge 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...
I am interested in landscape dynamics, generally focused on understanding and predicting changes in the patterns and functions of landscapes in response to anthropogenic effects. The objectives of my research are to gain an understanding of the processes that control landscape form and function as well and key interactions between hydrology, sediment transport, climate, vegetation, and human impacts in a variety of settings. Examination of these processes and interactions in different environments can ultimately lead to a more general and regional perspective of landscape morphodynamics and evolution. The recent research that I have initiated at USGS is a reflection of my direction and interests. I am keenly...
The acquisition and meaningful interpretation of sediment data from areas disturbed by land-use activities or natural processes are two of the most deficient areas of recognizing nonpoint-source pollution in the United States. The comparison of sediment data from disturbed and undisturbed areas provides a means to (1) evaluate the effects that land-use activities cause, (2) investigate the geomorphic processes that regulate the detachment and transport of sediment, and (3) develop strategies for remedial action to reduce excessive sediment discharges. This information is especially necessary to minimize sediment discharges and sorbed chemical loads from surface-mine, industrial, agricultural, and urban areas. Objectives...