Date of Award:

5-1988

Document Type:

Thesis

Degree Name:

Master of Science (MS)

Department:

Civil and Environmental Engineering

Committee Chair(s)

Christopher J. Duffy

Committee

Christopher J. Duffy

Committee

Keith Cooley

Committee

Craig B. Forster

Committee

Roland W. Jeppson

Abstract

Hydrologists have displayed a renewed effort towards understanding the complexity of runoff generation and its association with basin structure. Basin structure is defined as the complex geomorphological, vegetation, and soil characteristics that make up and distinguish the physical nature of a drainage basin. Zero-order basins are an integral part of watershed structure because they furnish the capacity to store and transmit snowmelt and rainfall. By definition, zero-order basins are sub-basins which are depressions in the surf ace and shallow bedrock topography. This study involves a space time characterization of a zero-order basin in fractured media located in southwest Idaho.

The purpose of the study is to gain insight into the relationships among subsurface flow, runoff generation, and basin structure. Topography, soils, geology, and infiltration rates play important role in controlling the flow of water within the hillslope. The spatial variability of these characteristics was analyzed to identify natural causal patterns.

Geophysical analysis defined five primary refractors loam soil, fractured basalt, semi-dense basalt, altered basalt, and dense basalt. The dense basalt and semi-dense basalt are relatively homogeneous, while the remaining three are heterogeneous. The Upper Sheep Creek Watershed is seismically diverse and complex.

The major source of water within the watershed is snowmelt, which provides the major contribution to subsurface flow within the drainage basin. Time moment analysis was used to analyze piezometer-streamflow response due to the pulse of melt water. This method provides the means to evaluate the evolution of annual hydrograph response between source, upslope, and downslope pulses and sort out separation times.

Natural-length scales of the surface and bedrock topography were used to create simple profile curves to approximate the spatial distribution of head along the hillslope. The separation of the surface and bedrock topography curves provides an envelope, wherein the normalized values of head can be plotted. This enables the position of the water table to be estimated at any location on the hillslope at any time of the year, provided that the length of the flow paths and head values are known and have been normalized.

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