U.S. Department of the Interior

U.S. Geological Survey

Fact Sheet 2012–3001

August 2012

RESEARCH AT THE USGS WESTERN GEOGRAPHIC SCIENCE CENTER

Decision-Support Systems for Natural-Hazards and LandManagement Issues

cientists at the USGS Western SGeographic Science Center are 

developing decision-support systems (DSSs) for natural-hazards and 

land-management issues. DSSs are 

interactive computer-based tools that 

use data and models to help identify 

and solve problems. These systems 

can provide crucial support to policymakers, planners, and communities 

for making better decisions about 

long-term natural hazards mitigation 

and land-use planning.

Decision-support systems (DSSs) are interactive computer-based tools that use data 

and models to help decisionmakers identify 

and solve problems. They are designed to 

assist decision making, rather than replace 

individual judgment. In an effort to provide 

crucial tools to policymakers, planners, and 

communities dealing with complex, dynamic natural-hazards and land-management 

issues (land-use choices), the U.S. Geological Survey (USGS) Western Geographic 

Science Center (WGSC) is developing three 

DSSs—the Land-Use Portfolio Model, 

Land-Use Simulation Model, and Ecosystem Portfolio Model.

DSSs can be used to help synthesize, visualize, and analyze the natural-science and 

socioeconomic information needed for making risk-reduction and land-use choices. They 

can help users (1) better define problems, (2) 

systematically review decisions they make, 

(3) analyze factors that influence those decisions, (4) identify available information on 

these factors, (5) determine effects of decisions made with and without desired information, and (6) provide transparency and 

justification of decisions. DSSs also can help 

support long-term management goals and 

priorities, evaluate “what-if” scenarios and 

tradeoffs, address problems with uncertainty, 

and lead to more effective decisions.

The Land-Use Portfolio Model

The Land-Use Portfolio Model (LUPM) 

is a geospatial, scenario-based risk-analysis 

tool designed to provide information to policymakers, planners, and communities to support decisions on investing wisely and cost 

effectively in risk-reduction measures for natural hazards. Natural hazards pose increasing 

challenges to society because more people 

are settling in areas at risk. The costs of natural disasters are enormous, while resources 

to reduce risk are limited. Deciding what actions to take to reduce future damage and loss 

is difficult because of the many uncertainties 

involved, such as the location, timing, severity, and impacts of a hazard event.

The LUPM provides a quantitative way to 

estimate the potential benefits and costs of various mitigation measures for different hazard 

scenarios, while taking into account various 

uncertainties. The LUPM uses information 

about hazard-event probabilities, values of assets at risk, conditional damage probabilities 

(damage at a location given that the hazard 

event occurs), and mitigation costs to estimate 

returns-on-investment for different mitigation 

policies. A mitigation policy consists of a portfolio of assets to mitigate, such as buildings 

and bridges, and a mitigation measure, such as 

more stringent building codes. Users can select 

sets of assets to analyze (for example, low-income residential parcels, businesses located in 

high-susceptibility zones, or critical facilities). 

Researchers have used the LUPM to conduct 

successful demonstrations for scenarios in 

California, Tennessee, British Columbia, and 

Indonesia. Information on the Land-Use 

Portfolio Model software can be found at 

http://pubs.usgs.gov/tm/tm11c4.

The Land-Use Simulation Model

The Land-Use Simulation Model (LUSM) 

(http://pubs.usgs.gov/of/2011/1275) is a 

geospatial, Web-based, land-planning tool 

designed to help scientists, managers, and 

stakeholders make decisions about allocatUSGS Western Geographic Science Center researchers are developing decision-support systems to help 

policymakers, planners, and communities. One such system is the Land-Use Portfolio Model, a scenariobased risk-analysis tool developed to provide information to support decisions on investing in naturalhazard-mitigation measures. It estimates expected values and uncertainties of losses, avoided losses, and 

rates of return on mitigation investment for specified mitigation policies and hazard scenarios. The sample 

results shown here are for a magnitude 7.1 earthquake scenario on the Coachella Valley fault in southern 

California. Earthquake shaking intensities for the scenario are shown as peak ground acceleration, as 

measured in percent g (g is the acceleration due to gravity or 980 cm/sec/sec). The estimated losses that 

would be avoided by installing earthquake-resistant bracing systems on mobile homes in all of the census 

tracts in the study area are shown in thousands of dollars. (USGS image by Jeff Peters.)

0 8 16 4 MILES

0 8 16 4 KILOMETERS

l

N

Palm Springs

Indio

Coachella

San Bernardino

Hemet

Expected avoided losses 

by census tract in 

thousands of dollars 

> 3,000–3,600

> 1,000–3,000

> 400–1,000

> 100–400

≤ 100

Peak ground 

acceleration,

in percent g 

0.33–0.38

0.21–0.32

0.13–0.20

0.09–0.12

0.06–0.08

PACIFIC

OCEAN

CALIFORNIA

Map

area

N
that can help visualize and compare potential 

impacts to multiple services across different 

urban growth/climate change scenarios. Two 

current applications in the Western United 

States include the Puget Sound, Washington, 

EPM and the Santa Cruz Watershed EPM 

(SCWEPM), along the border of southeastern Arizona and northern Sonora, Mexico.

The Puget Sound EPM focuses on ecosystem services provided by nearly 2,500 

miles of nearshore environment that includes bluffs, beaches, mudflats, kelp and 

eelgrass beds, salt marshes, gravel spits, 

and estuaries (http://geography.wr.usgs.

gov/pugetSound/index.html). This EPM 

analyzes scenarios of urban growth out 

to the year 2060. It examines potential 

changes to the nearshore, including fecal 

coliform pollution in commercial shellfish 

growing areas, beach visitation at State 

parks, and where seawalls and bulkheads 

may impact recreational beaches and 

spawning beaches for “forage fish.”

The SCWEPM addresses water concerns in an arid region (http://www.mdpi.

com/2071-1050/2/7/2044). It analyzes 

scenarios of land use and climate change to 

assess impacts to water-related ecosystem 

services, such as drinking and irrigation 

water, erosion, flood control, and biodiversity, and equitable access to these services 

for vulnerable populations.

The work of Western Geographic Science 

Center (WGSC) scientists on DSSs for natural hazards and land management is part of 

WGSC’s efforts to better understand causes 

and consequences of land-cover change. 

WGSC, supported by the USGS Geographic 

Analysis and Monitoring Program, works with 

communities to help provide them the crucial 

geographic, economic, and natural hazards 

information they need to make decisions to 

reduce unnecessary risk from interactions between people and their environment.

N

City of South

Lake Tahoe

Tahoma

Incline

Village

Carnelian Bay and

Kings Beach

Tahoe 

City

0 5 MILES 

0 5 KILOMETERS 

Lake 

 Tahoe

Laura Dinitz, William Forney,

and 

Kristin Byrd

Edited by James W. Hendley II

Graphics and layout by Judy Weathers

For more information, contact:

Laura Dinitz

U.S. Geological Survey

Menlo Park, CA 94025

Tel. (650) 329-4953

ldinitz@usgs.gov

http://geography.wr.usgs.gov

This Fact Sheet and any updates to it are 

available online at

http://pubs.usgs.gov/fs/2012/3001/

The Land-Use Simulation Model (LUSM) developed 

by the USGS Western Geographic Science Center 

is being used to examine land-use issues in 

the Lake Tahoe Basin on the California-Nevada border. These 

sample results show the 

likelihood that a parcel 

of land will transition 

from vacant to 

single-family 

dwelling.

N

Map

Area

CALIFORNIA

ing vacant parcels to another land use over 

periods as long as 20 years. Having evolved 

from the “Tahoe Decision Support System” 

(TDSS) (http://www.tiims.org/ScienceResearch/Environmental-Modeling/TDSS.

aspx), the LUSM provides scenarios and 

parcel-specific output to examine land-use 

change in the Lake Tahoe Basin and link it 

with other spatially explicit models. With 

further refinement and place-based considerations, the LUSM could have broad applications in other regions of the United States.

Lake Tahoe is situated in the high Sierra 

Nevada and is one of the deepest lakes in the 

United States. Its popularity brings positive 

economic value, as well as negative land-use 

impacts such as increased volume and timing of runoff, increased erosion, and reduced 

quality of water resources and native species’ 

habitats. Land-use planners in the region are 

challenged to balance economic growth with 

sustaining natural resources. The LUSM is 

helping them balance these needs.

In the LUSM, vacant parcels can transition 

to single-family dwellings, multifamily dwellings, commercial use, tourist accommodations, 

or be retired (remain undeveloped). A user defines an input scenario for allocating parcels, 

and the LUSM creates the output showing 

the likelihood of a parcel transitioning from 

vacant to some other use. This likelihood is 

based on the regulations of the many agencies 

with jurisdiction in the Tahoe Basin, but it also 

incorporates some randomness and uncertainty inherent in the decision-making process 

and in projecting the future.

The Ecosystem Portfolio Model

The Ecosystem Portfolio Model (EPM) 

is a Web-based tool designed to address 

region-specific planning needs related to 

protecting “ecosystem services,” which are 

the benefits people obtain from nature such 

as food, water purification, and recreation. 

Urban development and climate change 

can heavily impact ecosystem services. To 

ensure the long-term sustainability of ecosystem services, decisionmakers need to 

know where services are provided and the 

nature and magnitude of potential changes 

to these services. They also must be able to 

quantify how management options may lead 

to tradeoffs in supporting one ecosystem service over another. The EPM generates maps 

Lake Tahoe Basin

Probability of transition from 

vacant to single-family dwelling

Different fate in model

0.001–0.366 (1,764 parcels)

0.366–0.592 (2,574 parcels)

0.592–0.844 (240 parcels)

EXPLANATION