Chapter 19
Land-Use Planning and
Engineering Geology
Land Use Planning – Why?
• Safety?
• Is it the best use of a tract of land?
• Will the intended use be a misuse of the
land?
• Are the resources required (water – for
example) for the intended use available?
• Is there a potential for pollution from this
intended use of a tract of land?
Conversion of Rural Land
• Between 1997 to 2001 2.2 million acres of
rural land were converted to developed
uses
• The rate of development is accelerating
and the amount of available land has not
increased
• Some lands will not support any or all
forms of uses
Figure 19.1 a Land use in the United States
Figure 19.1 b Land converted to developed land
Considerations in Planning
• What is the optimum use of a tract of
land?
• We must consider:
– Biological factors
– Ecological factors
– Geological factors
– Economic factors
– Political factors
– Aesthetic factors
Land-Use Options
• Multiple Use – using the same land for two
or more purposes
– Parks or green areas used for recreation and
to catch fresh water during a storm to allow it
to infiltrate into the ground water
• Sequential use – utilize the land for two or
more different purposes, one after another
– Mines are used to provide the commodities
found in the subsurface, then they are re-used
for sanitary waste dumps, storage, or in-filled
for parks
Figure 19.3 Multiple land use
Figures 19.4 a and b Sequential Land Use
Federal Government and Land-Use Planning
• Historically, federal lands are not equally
distributed throughout the states
• Originally, federal emphasis was on resource
development rather than preservation
• Federal lands fall into two categories:
– Lands intended for preservation (national
parks and wilderness areas)
– Lands intended for multiple use and
compatible use such as grazing, logging,
mining, exploration and drilling for petroleum
(national forest)
Figure 19.5 Land ownership by state, 1997
Maps as a Planning Tool
• Land use planning requires abundant
information, maps often provide much
of the information:
– Topography, bedrock geology, surface
materials and geology, soils, depth to
ground water, vegetation, population
information, location of fault zones and
flood plains, and more
– Maps can assist planners in long term
planning, establishing restrictive zoning
for earthquake or flood hazards,
avoidance of other hazards as well
Figures 19.6 Map representation of geologic considerations
Figure 19.7 U.S. land-use classifications
Maps as a Planning Tool
• Computers have aided planners
– Information required by planners is voluminous
– Computers have played an increasing role for
planners to manipulate large volumes of
quantitative information
– Geographic Information Systems (GIS)
allow planners to manipulate the data to see
and use what data is useful to a planning task
while minimize, or obscuring, unimportant data
– GIS can allow a planner to see distinct “layers”
of information that are important to the decision
making process
Figure 19.8 Digitized maps can represent data
Figure 19.9 a composite map for land-use planning
Figure 19.10 a
Figure 19.10 b
Figure 19.10 c
Engineering Geology
• Geologic factors and considerations vary
depending on the site and the project
• A few considerations for a major project
may include:
• Rock types present in project area, are they
uniform or variable
• Are they fractured or faulted?
• If they are, are the faults active?
• Is there a landslide risk?
• What types of soil or soils are present? Are they
suitable for the project?
• What are the hydrologic factors? Surface and
subsurface
• The list is nearly endless
Figure 19.13 a Failure of structure on unstable soil
Figure 19.13 b Relative magnitudes of loss of life and
property damage from various geologic hazards
Engineering Geology
• Major projects often encounter major
obstacles
– Alaskan Oil Pipeline Project (1300 km long)
• Spans a variety of geologic settings (rock
types, structures, faults, slopes, soils,
mountains, streams)
• Active earthquakes, seasonal flooding,
animal migration routes – all required
solutions
• Climate factors – North Slope is very cold
with permafrost and a variable
permafrost table
Figure 19.14 a
Figure 19.14 b
Figure 19.15 permafrost and permafrost table
Figure 19.16 Differential subsidence of railroad tracks due
to partial thawing of permafrost
Role of Testing and Scale Modeling
• Models are physically constructed (at a
reduced scale)
• Models may be tested in a computer
• Failures of a variety of structures can be
tested – dams, bridges, or earthquake
resistant buildings
Fig. 19.18 Scale modeling
Case Histories
• Leaning Tower of Pisa: the flow of the
unstable soft clay layers
• Panama Canal: Dipping layers of young
volcanic rocks, lava flows, and pyroclastic
deposits and dipping beds of shale and
sandstone
• Boston’s “Big Dig”: Glacial sediments and
weakly metamorphosed mudstone
Fig. 19.20 Geologic
factors complicated
construction of the
Panama Canal
Figure 19.22 Boston’s “Big Dig”: Slurry walls keep excavations
from collapsing and nearby building foundations from failing
Dams - Failures and Consequences
• A catastrophic dam failure can impact many
cities, thousands of lives, and cause millions
of dollars worth of property damage
• St. Francis Dam: coarse sandstones;
schists and mica-rich metamorphic rocks; a
fault
• Baldwin Hills reservoir: an active fault
zone
• Three Gorges Dam: control the flooding,
enhance navigation, and produce energy
Figure 19.23 a Hoover Dam
Figure 19.23 b A regional overview of Hoover Dam
Figure 19.24 Failure of the St. Francis Dam in California
Figure 19.27 Benefits and issues in dam construction