Add Dataset to Cart565.18 GB
Authors: John Martin, Chris Paola
Start Date: 2003-01-01
End Date: 2003-09-01
The Delta Basin is a square flume measuring approximately 5 meters by 5 meters, and is 0.61 meters deep. The exact experimental configuration may vary depending on the scientific objectives - the specific scheme at right represents that for the DB03-1 and DB03-2 experiments.
A mix of sediment and water are introduced at a single infeed point in one corner of the basin. This produces a radially symetrical delta-like deposit. A syphon-based ocean controller at the opposite corner allows for precise base-level manipulation, and specifically for the creation of accomodation space via a slow base-level rise.
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Add Dataset to Cart22.02 MB
Experimental Study of Delta Erosion Due to Dam Removal
Authors: Alessandro Cantelli, Chris Paola, Gary Parker
Cantelli, A., Paola, C. and Parker, G., 2004, Experiments on upstream-migrating erosional narrowing and widening of an incisional channel caused by dam removal, Water Resources Research, 40, W03304, doi:10.1029/2003/WR002940 The present paper reports on a laboratory investigation of the erosion of a deltaic front induced by the removal of a dam. We built a laboratory model of a dam, and observed both the sedimentation in the reservoir due to the downstream propagation of a delta front and the erosion of the delta front during dam removal, including measurement of channel morphology and flow field. Based on an analysis of bank erosion two principal erosive trends were detected: during the initial stage of erosion the width of each section quickly decreased to a minimum value, after which the section widened. Undistorted Froude similitude is used to scale the results up to field dimensions.
Add Dataset to Cart143.17 GB
Riparian Vegetation and Braided Stream Dynamics
Authors: Efi Foufoula-Georgiou, Chris Paola, Michal Tal, Elizabeth Tilman
1. To study and quantify the interactions between riparian vegetation, channel morphology, and flow dynamics.
2. To investigate how river systems self-organize as a result of these interactions.
3. To investigate spatial and dynamic scaling in braided rivers with and without vegetation.
Reseachers: Michal Tal, Chris Paola, Elizabeth Tilman (Water Resources, Univ. of MN), Efi Foufoula-Georgiou (Civil Engineering, Univ. of MN)
Ongoing experiments at the St. Anthony Falls Laboratory are designed to isolate the effects of vegetation on braided stream dynamics. These experiments show how a fully braided stream with a noncohesive bed transitions to a single-thread (meandering) system when continuously forced with vegetation. Time-lapse photography and measurements of bed topography, flow depth, sediment output, and flow velocities enable us to study and quantify the morphodynamics of the system associated with this change.
Add Dataset to Cart617.95 GB
Authors: Alessandro Cantelli, Wonsuck Kim, John Martin, James Mullin, Chris Paola, Nikki Strong
The XES facility is a large experimental basin (13 m x 6.5 m), developed and built with funds from NSF and the University of Minnesota , that permits the formation of stratigraphy through the use of a flexible subsiding floor. The goal is to reproduce the real-world (i.e. spatially variable) kinematics of subsidence, as determined by geophysical modeling and backstripping of real basins.
The floor is a honeycomb of 432 independent subsidence cells (Fig. 1) through which a gravel "basement" is slowly removed to provide accommodation space for deposition. At the beginning of an experiment, the basin is filled with dry, well sorted commercial gravel. The top of the gravel is covered with a thin rubber membrane. The experimental deposit is formed on top of this membrane. Subsidence is induced by withdrawing gravel from the bottoms of the hexagonal cells. Each hexagon forms the top of a cone that tapers into a standard elbow pipe (Fig. 2). The gravel in the cone rests at the angle of repose in this elbow. Subsidence is induced by firing a pulse of high-pressure water into the gravel in the elbow. A small volume of gravel is knocked out of the elbow and falls into an exhaust line, where it is transported out of the system and stored for later reuse. Each subsidence cell has its own sealed pressure tube that drives the pulses via a computer-controlled solenoid valve. We have refined and calibrated the pulsing so that each pulse produces about 0.12 mm of subsidence: the "earthquake slip" in the experiments. This is about equal to the resolution with which the basement elevation can be read (described below), and also to the typical grain size of sediment in the experiments. Hence the subsidence is effectively smooth and continuous in time. The subsidence is also spatially continuous. The cells are separated only at floor level, so the gravel can flow laterally to accommodate differential subsidence with no breaks at the cell boundaries. Firing a single cell, for instance, produces a smooth bowl-shaped subsidence pattern that extends over the six adjoining cells. Extensive testing has shown that the underlying honeycomb structure is not imprinted on the subsidence at the surface until the rubber membrane (the top of the basement) has been lowered to within about 0.2 m of the honeycomb. This leaves about 1.3 m of usable accommodation space in the basin. As long as the gravel basement is loaded, lateral slopes of up to 60 can be produced between adjoining cells
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