sediment supply

Spatial and temporal patterns of water quality indicators in reef systems of southwestern Puerto Rico

Otero E.E. Spatial and temporal patterns of water quality indicators in reef systems of southwestern Puerto Rico. Carribbean journal of science, Vol 45, Is 2-3, 2009, pp. 168-180

Hydrologic Modeling of Land Processes in Puerto Rico Using Remotely Sensed Data

Hydrologic Modeling of Land Processes in Puerto Rico Using Remotely Sensed Data
Cruise, J. F.; Miller, R. L.
Journal of the American Water Resources Association, vol. 30, Issue 3, p.419-428

Abstract: 
An integrated, multi-disciplinary effort to model land processes affecting Mayaguez Bay in western Puerto Rico is described. A modeling strategy was developed to take advantage of remotely sensed data. The spatial, interannual, and seasonal variability of sediment discharges to the bay were also evaluated. Classified images of remotely sensed data revealed the spatial distribution and quantities of land use classes in the region and aided in the discretization of the watershed into homogeneous regions. These regions were modeled using a geomorphic modeling technique based upon spatially averaged parameters. Simulation results from the modeling effort compared favorably with observations at two locations within the watershed. Results showed that runoff and sediment loads from the area exhibit a marked seasonal trend and that deforested areas located in the foothill regions of the watershed contribute a disproportionate share of the sediment load to the bay. In years when rainfall distributions are uniformly distributed over the area, the sediment yields may be up to 100 percent higher than years when the rainfall is concentrated in the heavily forested mountainous regions.

Effects of land-use change on channel morphology in northeastern Puerto Rico

Clark, J. J., and P. R. Wilcock (2000), Effects of land-use change on
channel morphology in northeastern Puerto Rico, Geol. Soc. Am. Bull.,
112(12), 1763– 1777.

Abstract: 
Between 1830 and 1950 much of northeastern Puerto Rico was cleared for agriculture. Runoff increased by 50% and sediment supply to the river channels increased by more than an order of magnitude. Much of the land clearance extended to steep valley slopes, resulting in widespread gullying and landslides and a large load of coarse sediments delivered to the stream channels. A shift from agriculture to industrial and residential land uses over the past 50 yr has maintained the elevated runoff while sediment supply has decreased, allowing the rivers to begin removing coarse sediment stored within their channels. The size, abundance, and stratigraphic elevation of in-channel gravel bar deposits increases, channel depth decreases, and the frequency of overbank flooding increases downstream along these channels. This is presumed to be a transient state and continued transport will lead to degradation of the bed in downstream sections as the channel adjusts to the modern supply of water and sediment. A downstream decrease in channel size is contrary to the expected geometry of self-adjusted channels, but is consistent with the presence of partially evacuated sediment remaining from the earlier agricultural period. Reverse (downstream decreasing) channel morphology is not often cited in the literature, although consistent observations are available from areas with similar land-use history. Identification of reverse channel morphology along individual watercourses may be obscured in multiwatershed compilations in which other factors produce a consistent, but scattered downstream trend. Identification of reverse channel morphology along individual streams in areas with similar land-use history would be useful for identifying channel disequilibrium and anticipating future channel adjustments.

Fluvial Processes in Geomorphology and Environmental Management: The 2006 Benjamin Franklin Medal in Earth and Environmental Science awarded to Luna B. Leopold and M. Gordon Wolman

Frederick N. Scatenaa, and Robert D. Varrin
Fluvial Processes in Geomorphology and Environmental Management: The 2006 Benjamin Franklin Medal in Earth and Environmental Science awarded to Luna B. Leopold and M. Gordon Wolman
Journal of the Franklin Institute
Volume 347, Issue 4, May 2010, Pages 688-697
The 2006 Franklin Institute Awards

Abstract: 
Starting in the 1950s Luna B. Leopold and M. Gordon Wolman transformed the field of geomorphology with quantitative and process-orientated studies designed to understand landscape adjustments to temporal and spatial changes in sediment supply and streamflow. By integrating fundamental science with keen observations they developed the first comprehensive and mechanistic understanding of rivers and floodplains. Their research has not only provided a quantitative framework for understanding landscape evolution, it is a cornerstone of modern water resource management and environmental impact analysis. Specific research areas included quantifying: (1) the “hydraulic geometry” of rivers; (2) the morphology and processes of rivers; (3) channel networks and the longitudinal profiles of rivers; (4) processes controlling floodplain formation; (5) the magnitude and frequency of geomorphic processes; and (6) the cycle of sedimentation in response to urban development. Much of this research was published in seven co-authored articles and in a widely used 1964 book that they co-authored with John Miller, Fluvial Processes in Geomorphology. While their contributions are synergistically linked and stem from their co-authored papers, their individual contributions are distinct and extend over 50 years. For these accomplishments, Luna Leopold and M. Gordon Wolman were awarded the 2006 Benjamin Franklin Medal in Earth and Environmental Science.
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