Geologic, Hydrologic, and Urban Hazards for Design in Desert Environments - Design with the Desert: Conservation and Sustainable Development - page 89

5
Geologic, Hydrologic, and Urban Hazards
for Design in Desert Environments
Robert H. Webb, Stanley A. Leake, and Richard A. Malloy
CONTENTS
5.1 Introduction .......................................................................................................................... 91
5.2 Flood Hazards ...................................................................................................................... 92
5.3 Mass Wasting: Debris Flows and Rockfalls ..................................................................... 98
5.4 Land Subsidence ................................................................................................................ 101
5.5 Earthquakes ........................................................................................................................ 103
5.6 Other Geologic Hazards ................................................................................................... 105
5.6.1 Radon ....................................................................................................................... 105
5.6.2 Expansive Soils ....................................................................................................... 105
5.7 Urban and Man-Made Hazards ....................................................................................... 105
5.7.1 Regulatory Environment ...................................................................................... 106
5.7.2 Mining Pollution .................................................................................................... 107
5.7.3 Hazardous Wastes ................................................................................................. 109
5.7.4 Superfund Sites ...................................................................................................... 110
5.7.5 Brownfields ............................................................................................................. 111
5.7.6 Air Quality .............................................................................................................. 112
5.7.7 Stormwater Pollution ............................................................................................. 113
5.7.8 Vegetation Hazard ................................................................................................. 113
5.8 Summary ............................................................................................................................. 114
References ..................................................................................................................................... 115
5.1 Introduction
Settlement of the arid parts of the western United States required access to reliable water
supplies, and the location of towns and the design of structures paid little heed to hazards
inherent in this environment. Beyond the rattlesnakes and scorpions, a variety of geologic
hazards pose substantial threats to urban and rural infrastructure. Settlers who chose to
build along channels that offered dependable water quickly learned that flash floods are a
significant problem when their irrigation dams and houses washed away. Others had their
homes, often made of mud bricks, fall down during earthquakes. Waste was dumped into
the ground or in waterways, or burned, fouling the air. Much of our knowledge of geologic
and hydrologic hazards in the desert Southwest comes from the cumulative experience of
settlers and their descendents with hazards, either natural or human-caused, and the net
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