- Las Vegas, Nevada, USA
- Western Urban Expansion
- Southwestern Las Vegas
- Change Animation
- Lake Las Vegas
- Lake Mead
- Land Cover Maps
- Near Lake Mead
- Impervious Surface
Las Vegas, Nevada, is one of the fastest growing metropolitan areas in the United States. Las Vegas grew from a population of 1,375,765 in 2000 to 1,951,269 in 2010, a 41.8% increase, third highest in the country for that decade. These images show the rapid growth of the city. The tip of Lake Mead is visible east of the city (dark area), where Hoover Dam impounds the Colorado River.
We have created an animation to make it easier to visualize the progression of the changes in Las Vegas. Click the subsection “Change Animation” to view that short video.
Population growth of the Las Vegas Metropolitan Area
In these false-color images, bright green indicates vegetation. As the city expands, you can see a sort of land cover succession as people build on the desert landscape.
- Non-developed land cover appears orange-brown in the Landsat 5–8 images. This color comes from sparse desert vegetation, reddish soils, and rock.
- Construction land appears brighter than surrounding land. Bulldozed soil, bare of vegetation, is very reflective of light.
- A young neighborhood appears a little paler green than older neighborhoods. The trees are small, and some developments conserve water by landscaping with rock and desert plants rather than grass.
- An old neighborhood is slightly darker green than new neighborhoods from the mature trees and more grass.
- Golf courses appear bright green because they are mostly pure pixels of vegetation. Residential areas are darker green because the pixels there are a mixture of trees and grass along with structures. New golf courses tend to be incorporated into residential developments, while older courses tend to be separate.
- Water (2) appears almost black because water typically absorbs solar radiation at the wavelengths depicted in these images. Like golf courses, water is sometimes integrated into residential developments for recreational purposes.
Zooming in on the southwestern portion of the city reveals further urban and suburban changes.
McCarran International Airport expanded in this timeframe to accommodate the population and tourism growth. One way to expand an airport is to pour a lot of concrete. Compare the 1986 and 1992 images. The addition of east-west runways can be clearly seen. You can also see the addition of a new terminal and gates in the 2000 image, located to the east (right) of the present terminal. These “D” gates opened in 1998. The 2010 image reveals additional expansion of the “D” gates, as they take on the final X shape.
More new golf courses show up in this part of the urban area throughout the images. For example, the Rhodes Ranch Golf Club shows up in the 2000 image just south of where a new highway curves in the western part of the image. In the 2016 image, it’s already surrounded by residential areas. Landsat data can help people in fast-growing cities plan for future growth.
In the western part of the 2000 image, we see the newly completed highway, Clark County 215. Compare the 2000 image and the 2016 image: what effects do new highways have on a location? Suburbs often develop along main highways, and the growth of residential and retail areas near and along the new highway demonstrate that type of urban growth.
If you could speed up time and watch a fast-growing city like Las Vegas change, what would it look like? From the perspective of the Landsat satellites, it’s a stunning lesson in urban growth. Watch Las Vegas’ rapid expansion in this animation created from Landsat images dating back to 1972.
In each image, bright red indicates actively growing vegetation. This makes golf courses easy to spot, and their development can be tracked along with the residential areas that surround them.
The desert landscape gradually becomes covered with streets, highways, and development as time goes on. A plot of very light tan can sometimes be seen right before a new residential area is built. This indicates a clearing of the land.
Other natural bright areas also appear around the urban development. The bright reflection indicates the presence of salts, minerals, and clays in the sediment. Water once settled in these flat, lower elevation areas and these minerals remained. The brown-tan regions surrounding the city are likely steeper slopes where flowing water rinsed out those minerals. Darker tones indicate coarser material, and lighter tones are fine material such as clays that have a higher reflectance.
Each image represents about one year from 1972 to 2016. Landsats 1–5 and Landsat 7–8 are represented in this movie, which demonstrates the value of the past Landsat data along with new data for monitoring change over time. Landsat images are available to the public at no cost at the USGS Global Visualization Viewer (http://glovis.usgs.gov) or EarthExplorer (http://earthexplorer.usgs.gov).
Between 1986 and 1992, a lake appeared east of the city, along Las Vegas Wash, a riparian area. This is Lake Las Vegas, a privately owned lake that is part of a commercial residential resort. You can see that unlike Lake Mead, it is fringed with land that has been cleared for building. This appears as a bright halo in the 1992 Landsat image. After 1992, golf courses and residential and resort buildings were built up along the shores of the southern portion of the lake.
How is Las Vegas getting enough water for its expanding population? Most of it comes from Lake Mead on the Colorado River. The Colorado River provides water for Las Vegas, as well as Phoenix, Los Angeles, and San Diego. As the populations of all of these cities continue to grow, water demand also increases. However, less snowpack in the mountains in recent years has reduced the river’s flow and thus the amount of water stored in the reservoir.
Landsat images starting in 1972 show the changing water level of the lake. The lowest level is represented in the most recent image in 2016.
In June 2016, Lake Mead’s water level fell to 1,071 feet above sea level. The level hasn’t been this low since the lake began filling in the 1930s. The January 2016 level of just under 1,084 feet above sea level was the lowest January level on record since the lake began filling. In March 2016, the lake was reported to be 39% full.
The drop in lake level isn’t even as apparent as it might otherwise be because of the steep topography in the region. Lake Mead is inside a canyon environment, so the drastic reduction in lake level does not equate to as drastic of a reduction in surface area, even though the surface area reduction is quite noticeable.
The images displayed in this section show a different way of looking at change over time. These images are part of the National Land Cover Database (NLCD), generated and distributed by the USGS EROS Center and a group of federal agencies called the Multi-Resolution Land Characteristics (MRLC) Consortium.
NLCD portrays land cover change spatially as a comprehensive “wall-to-wall” 30-meter resolution database. Its national coverage supports many different applications: fire, urban development, insect damage, mining, best practices in land management, and more.
NLCD is based on multiple dates of Landsat imagery captured across the growing season, which is combined with other ancillary data in models to finalize the products. The available editions of NLCD are from 1992, 2001, 2006, and 2011. NLCD 2016 is currently under development.
The legend below shows which colors correspond to the different types of land cover. For example, red indicates impervious surface. This means developed, or built-up, land. Pink is less intensively developed urban areas, and darker red is more intensively developed. Urban land shows the most obvious change seen in these NLCD maps of Las Vegas.
The dominant land cover surrounding Las Vegas is “shrub/scrub,” which is shown as tan. These areas are dominated by shrubs less than 5 meters tall.
NLCD Land Cover Classification Legend
These close-up NLCD images show the water level changes to western Lake Mead. The water classification (blue) changes to barren ground (gray) as the lake shrinks from 2001 to 2011.
Golf courses show up as developed land. Even though they have vegetation (as indicated in the Landsat images as bright green), here they show up as developed, open space. This faded pink color is also used to indicate lawn grasses in large-lot single-family housing units, parks, and other vegetation planted for aesthetics.
The dark red is urban areas, and in the lower center of image is Boulder City, NV. The faded pink is conspicuous as golf courses, but another pink and red line traces toward the left—a highway that leads from Boulder City to part of Henderson. Around Lake Las Vegas are more golf courses and development in the upper left. The River Mountains occupy the blank tan space to the left of Lake Mead.
NLCD images of western Las Vegas show that much more urban expansion took place here between 2001 and 2006 than over the next 5 years. The land cover classes that expand noticeably in these images are the developed classes. With these classes, NLCD can be used to track changes to impervious surface.
Impervious surfaces include roads, buildings, and parking lots—surfaces that do not allow rainwater to soak into the ground. The extent and density of impervious surface can affect water quality and flooding severity in urban areas.
In a forested area, for example, most rainfall soaks into the soils and is stored as groundwater, slowing the discharge into streams. Flooding in these areas is less significant. In urban areas, however, much more water runs off into streams quickly and increases the likelihood of severe flooding.
Studying impervious surface change allows scientists to quantify the extent of developed land cover regionally and nationally. NLCD is widely used to evaluate effects on hydrological and ecological systems in many urban areas.
Impervious surfaces are best measured with satellites. They cannot be easily or cost-effectively measured on the ground.