Physical Setting

Owens River runs from just south of Mono Lake through Owens River Gorge to the head of Owens Valley, and from there the length of Owens Valley to Owens Lake. This study was limited to Owens Valley.

Below Owens River Gorge, Owens River is a meandering, low-gradient stream (fig. 1), winding over a floodplain whose width varies from less than 100 m. to more than 1 km. The floodplain lies at a lower elevation than the rest of the valley floor and is bounded by abrupt bluffs along much of the river. The floodplain surface is crisscrossed in many places by abandoned river meanders, but is otherwise fairly level. The river channel is relatively deep and narrow, bordered in many places by steep banks composed of fine-textured, cohesive alluvium.

The Owens River system is fed almost entirely by runoff from the Sierra Nevada, but even before man altered the hydrologic regime only about a third of its Sierra tributaries maintained perennial flow to the river. The rest normally disappeared short of the river channel as a result of percolation and evaporation. Much Sierra runoff thus reaches the river as subsurface flow. South of the Poverty Hills, however, the 1872 earthquake fault (fig. 1) restricts eastward groundwater movement (Los Angeles Department of Water and Power 1966). No groundwater reaches the river channel where it lies well east of the fault, but seepage increases gradually above the intersection of river and fault near Manzanar Road. From there south to Lone Pine many small springs occur in and along the channel, probably the combined result of channel entrenchment, proximity of the earthquake fault, and inflow from the alluvial fan of Lone Pine Creek.

Under natural conditions, maximum monthly discharge of Owens River normally occurred in June or July with melting of the Sierra snowpack; minimum discharge usually came in August or September. River flow was comparatively regular: the ratio of maximum to minimum monthly discharge at Pleasant Valley from 1919 through 1940 was 2.8 to 1^[3] —much lower than, for example, the Kings River at Piedra (46.4 to 1); the Kern at Bakersfield (13.4 to 1); and the Kaweah at Three Rivers (53.6 to 1) (USDI Geological Survey 1959). Factors responsible for this low variation may

[1] Paper presented at the California Riparian Systems Conference. [University of California, Davis, September 17–19, 1981].

[2] Timothy S. Brothers is a Graduate Student in the Department of Geography, University of California, Los Angeles, Calif.

[3] Unpublished streamflow records, Los Angeles Department of Water and Power (LADWP).

Figure 1.
Owens Valley.

have included the gentle gradient of the river channel; low precipitation east of the Sierra crest and regulation of the discharge by the Sierra snowpack and groundwater. River regime and channel morphology suggest that most floods were relatively mild events, causing little disturbance of the floodplain surface.