Date of Award

10-2014

Access Restriction

Thesis

Degree Name

Master of Science

Department

Environmental Science & Civil Engineering

School or College

Seaver College of Science and Engineering

First Advisor

Jeremy S. Pal

Second Advisor

Jose A. Saez

Abstract

Antelope Valley is situated in Southern California and is bounded by the Tehachapi and the San Gabriel Mountains. It stretches over 2,200 mi2 and encompasses Rosamond Dry Lake and the 1,200 mi2 watershed draining into it. The cities of Lancaster and Palmdale are the two major urban centers that lie in the watershed draining into Rosamond Dry Lake. The lake lies within the vicinity of the Edwards Air Force Base and provides an important site for aviation research and test operations in addition to ecosystem services. Hence, it is necessary to balance the need to remove water from the lake to support Edwards Air Force Base’s aircraft missions and the need to inundate the lake to protect the its surface and the ecosystem it supports.

In this study, satellite-based elevation, state of the science land cover and soil data are used to create a model that predicts storm runoff volume into Rosamond Dry Lake. Geographical Information Systems software is used delineate and divide the watershed into 98 sub-basins. Each sub-basin is assigned a land cover type, percent impervious area, and hydrologic soil type to calculate the Natural Resource Conservation Service curve number. The model also incorporates two detention basins to represent existing flood control structures in Lancaster and Palmdale. Runoff in each subbasin is estimated using the Natural Resource Conservation Service Curve Number method and accumulated into the channels.

In a hydraulic modeling software developed by the Army Corps of Engineers, the modeling system is applied to calculate the total storm runoff volume into Rosamond Dry Lake for ten historical storm events as well as a 100-year event. Due to the lack of stream gauge data, a technique that couples Landsat 7 satellite images of Rosamond Lake with LIDAR elevation data to estimate observed runoff volume is developed to evaluate model performance. In comparison to these estimates, the model overestimates runoff volume by approximately 7%. However, there are considerable biases for two storm events that are caused by the effects of evaporation, wind and snow on the lake’s water and various deficiencies in the model.

The impacts of past and future urbanization on the runoff volume into the lake are examined by modifying the curve number in sub-basins representative of the urban centers. For a 100-year, 24-hour, precipitation event, urbanization results in increased runoff at both the sub-basin and watershed levels. Additional simulations indicate that measures such as building detention basins and repurposing unused or undeveloped areas within an otherwise developed area (infill) can mitigate increased runoff due to urbanization.

Overall, the model proves to be an effective tool for predicting runoff into Rosamond Dry Lake. It can also be used to study the rainfall-runoff processes in the lake. The ability to predict water volumes in the lake will allow engineers and planners to establish a balance between the Air Force Base’s aircraft missions and the lake’s ecological function. Lastly, the techniques used to develop the model can be used to develop similar models for other watersheds. iii

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