fforts are already in place for many locations. For 2014, there is potential for major agricultural impacts, and the wildfire danger is expected to be unusually high.
These three images show a portion of California’s Central Valley (left side of the images) and the neighboring Sierra Nevada mountains as viewed by Landsat in February 2011, 2013, and 2014.
The decrease of winter snow cover can be seen in this progression of images. The reduction of available water supplies in the Central Valley is also indicated by the changing outlines of Folsom Lake, Camanche Reservoir, and other lakes and reservoirs in the images.
The 40-year archive of Landsat imagery is useful for monitoring the changing conditions of Earth’s surface areas through time.
Urban and Agricultural Change in Cairo, Egypt April 11, 2014
Egypt’s capital city of Cairo lies in the fertile Nile River Valley. Historically, Cairo and its agricultural areas have been geographically limited by natural desert borders, but these patterns are changing due to recent reclamation of surrounding desert land.
These two images were acquired by the Landsat satellites in 1987 and 2014. During this time period, Cairo’s population has increased from an estimated 6 million in 1986 to over 15 million in 2014.
The recent population growth has caused the city and its associated urban areas to expand into the surrounding desert, as seen in the second image. Within the main Nile River Valley, these two images also show an overall increase in developed urban area (grey/brown) versus previous agricultural land use (green).
As new urban and agricultural areas are being developed in the desert, they require diversion of water supplies from the main Nile River Valley. This expanded irrigation is indicated by the numerous bright green areas throughout the second image.
The Landsat data archive spans more than 40 years and provides a valuable record of changes on the Earth’s surface, including urbanization and agricultural land use change.
On March 22, 2014, a massive landslide occurred in the Cascade Mountains near Oso, Washington. Triggered by heavy rains, the slide covered the North Fork of the Stillaguamish River and destroyed numerous homes. After a week of intensive search and rescue efforts, at least 20 deaths had been reported and many others were still reported missing. The muddy debris also created a dam that blocked the river, causing concerns for flooding and flash flooding as the water filled behind and moved around the dam.
These images were acquired by Landsat 8 on January 18, 2014, and again on March 23, 2014. Along with the landslide, the barrier lake caused by the blocked river channel can also be seen in the later image.
Landsat imagery will be useful (along with other datasets) as the efforts to recover, reclaim, and restore this area are implemented.
These Landsat images show the Sesan River (Tonlé San), which runs through the boundary region between northeast Cambodia and Vietnam. The river forms an important tributary to the Mekong River, which lies to the west (not shown). The two images were acquired in 1989 (left) and again in 2014 (right).
These images are “false-color composites.” The red tones are due to a strong signal from Landsat’s near-infrared (NIR) band, which is often used by landscape scientists to monitor the presence and condition of vegetation and forested areas. The lighter tones in the 2014 image show where vegetation has been cleared for logging, mining, or other land use purposes.
The Yali (Yaly) Falls Dam was built in 1993–1996, and its associated reservoir can be seen on the right side of the 2014 image.
The information contained in images such as these can be used to understand the landscape conditions at any location worldwide, and the 40-year record of Landsat allows scientists and others to monitor changes to this landscape over time.
Yarki Island and Lake Baikal, Russia March 14, 2014
Located in southern Siberia in Russia, Lake Baikal is the deepest lake in the world (1,700 m) and contains 20 percent of the fresh surface water on the planet.