Island-Building in the South Pacific August 4, 2015
An undersea volcano between the two small islands of Hunga Tonga (right) and Hunga Ha’apai (left) began erupting in early December 2014. After about a month of eruptive activity, a new landmass had formed, nearly joining the two islands.
This series of Landsat 8 images shows the two islands in October 2014 (before eruptions), in December 2014 (during the eruptions), and in July 2015 (after the eruptions).
Along with creating new landmass, the volcanic activity has also radically changed the islands’ ecology. The first panel shows vegetation cover (green) on both of the original islands. The predominantly gray and brown colors in the third image now indicate bare land surface, especially on the southeastern island.
Landsat images are often useful for mapping changes to the Earth’s land surface. Future images will also allow scientists to monitor any changes and long-term recovery of vegetation and land cover
Laguna Pastos Grandes is a shallow salt lake located in Bolivia’s Pastos Grandes volcanic caldera. Fed by intermittent rivers and springs, the lake contains high concentrations of lithium, potassium, and boron. These three images show how Landsat 8’s extended spectral capabilities can be used to highlight various surface features, often with vibrant results.
The left image uses the three visible bands from Landsat (red, green, and blue) to create a natural color representation. In this image, the ground features appear in colors very similar to what would be seen by the human eye. Non-vegetated ground is brown, and water appears dark. The bright areas indicate salt and other evaporated deposits in dry or very shallow areas of the lake.
Along with the visible wavelengths, Landsat 8’s extended spectral bands show additional details that cannot be seen by the human eye. The middle image uses two infrared bands that can be used to highlight the water bodies (red), salt and evaporated deposits (yellow, gold), and varying composition of other materials (green, tan) within the basin. The right image also uses infrared bands, but in a different combination which accentuates the salt and evaporated deposits (light blue) and the geologic features within the surrounding volcanic region (brown, green).
The many spectral bands available on Landsat provide an important set of tools for scientists, geologists, and others to study and map features on the Earth’s landscape. These features cannot always be seen by the human eye alone.
Near the western edge of the Sahara Desert is a feature that resembles a large eye when viewed from space. The Eye of the Sahara, also known as the Richat Structure or Guelb er Richat, is a symmetrical dome of eroded sedimentary and volcanic rock. The outermost rings measure approximately 40 km (25 miles) across. Persistent northeasterly winds keep much of the dome free from sand, exposing the various layers of rock. The circular feature was initially interpreted to be an asteroid impact structure, but most scientists have now concluded that it was caused by geologic uplift.
This Landsat mosaic of four different scenes shows the geologic feature in false color. By blending visible and infrared wavelengths (bands), scientists can enhance the visibility of the various rock layers in contrast to the surrounding sand (yellow to white).
The largest mud volcano in the world is located in Porong, Sidoarjo in Indonesia, where it is locally called the Lusi Mud Volcano. Mud volcanoes are created when hot mud (rather than lava) erupts from a vent on the Earth’s surface. This type of eruption typically includes a mixture of steam and gas, groundwater, and mud-based slurry.
Lusi first erupted in May 2006, and is expected to continue erupting for decades. So far, enough mud has erupted to cover nearly 27,000 football fields in a meter of mud. These two Landsat images were acquired by Landsat 7 on April 28, 2006 (left) and June 24, 2015 (right). The round feature in the center of the right-hand image shows the current extent of the mudflow. This second image also shows a series of levee structures that were built in 2008 to surround and contain the ongoing mudflows.
The Landsat sensors include numerous spectral bands that can be used in various combinations, allowing users to accentuate and study specific features on the Earth’s surface. These two images used a combination of shortwave and near-infrared wavelengths to highlight the mudflow area, in contrast to the surrounding urban and agricultural areas.
The afternoon of Sunday June 14, Alaskan authorities were notified of a 40-acre fire in Willow, AK. Named the Sockeye Fire for the street where the fire began, the fire moved quickly through the black spruce forested area due to flat topography and hot, dry, windy weather. In only 48 hours, the burned area grew to about 6,500–7,000 acres. Strong north winds are expected to drive the fires to the south, threatening populated areas. Smoke could affect Anchorage, 80 miles to the south.
These two Landsat images were acquired by Landsat 8 on May 30, 2015 (left) and June 15, 2015 (right). Bright red indicates where the fire is burning. Burned areas are dark shades, and smoke from the fire forms a hazy trail toward the south. The Susitna River, to the west of the burned area, acts as a natural firebreak.
Landsat imagery assists with response planning and identification of areas at further burn risk. Future Landsat imagery will be useful for mapping and measuring burned areas and monitoring vegetation recovery.
Heavy rains fell over Texas, Oklahoma, Arkansas, and Louisiana in late May 2015. Many lakes and rivers filled and overflowed their banks, causing widespread flooding in both urban and rural areas. These rains provided much-needed moisture for this area of the southern Plains, and may help to suspend a multiyear drought in the region. However, the rapid rate of the rainfall has been excessive for many areas.
These images show the Trinity River southeast of Dallas, Texas. In the May image, the river can hardly be seen because of the vegetation along its banks. The June image shows Trinity River and flooded regions in bright blue and dark tones.
As the water moves downstream, continued flooding is affecting many homes, businesses, and cropland within Texas and its neighboring states. Future Landsat images will help with the monitoring and evaluation of impacts, as the waters crest and begin to recede.
2015 Earthquake and Landslides, Nepal May 27, 2015
A magnitude 7.8 earthquake struck Nepal on April 25, 2015. Along with damage due to shaking, the earthquake and its aftershocks triggered many large and small landslides throughout the region. As of early May, over 3,000 individual landslides had been identified, based on analysis of hundreds of satellite images collected after the earthquake.
The background image above is a Landsat 8 mosaic of the entire region, produced by stitching together Landsat images acquired from 2013–2014.
The insets show an image pair acquired by WorldView-2 and WorldView-3 over one example location near the town of Namrung, Nepal. Comparing the image acquired shortly after the earthquake with an image from a previous date allows scientists to map the exact locations and extent of local changes caused by the landslides. Here, the post-event (May 8) WorldView-2 image shows one major landslide, as well as many smaller-scale slides that also occurred along the Buri Gandaki river valley after the earthquake. The image also shows a new lake that formed behind the largest landslide, as a result of damming of the Tom Khola River.
This inset image pair shows just one location, and these changes have occurred across the landscape, especially in the mountainous regions.
Scientists will continue to monitor the region with various satellite data. As post-event images become available, earthquake damage and landslide maps are being created and updated. For more information (including earthquake damage assessments and a landslide inventory map) see the International Charter ‘Space and Major Disasters’ home page: https://www.disasterscharter.org.
35th Anniversary of Mount St. Helens Eruption May 20, 2015
The violent eruption of Mount St. Helens 35 years ago permanently changed the mountain and surrounding forest. The volcanic blast on May 18, 1980, devastated more than 150 square miles of forest within a few minutes. In these Landsat false-color images, forest appears as bright red interspersed with patches of logging. Snow appears white, and ash is gray.
Before the eruption, Mount St. Helens towered about a mile above its base, but when the volcano erupted, its top slid away in an avalanche of rock and debris. When measured on July 1, 1980, the mountain’s height had been reduced from 9,677 feet to 8,364 feet—a difference of about 1,300 feet.
The 2014 Landsat image shows vegetation regrowth, as light red and pink, in the devastated area. However, the gray around the mountain is still evident, and the volcanic crater is still prominent as an “amphitheater,” where the peak of the mountain slid away.
Scientists are using this opportunity to witness the recovery process, both with satellites and on the ground. With its 40-plus years of consistent imagery, the Landsat archive is perfect for studying the landscape changes caused by natural disasters and the gradual recovery process.
Haruj is the large volcanic field that dominates this Landsat image mosaic acquired over central Libya. The plateau was built from basaltic lava flows that erupted over time from approximately 150 separate volcanoes. The volcanic craters and lava flows are all evidence of a previous active period, well preserved in the dry Sahara Desert.
The geologic evolution of this landscape is not fully understood, but some scientists have used the texture and color differences revealed in satellite images to try to interpret the relative ages and sequence of different volcanic events. The numerous spectral bands and band combinations available from Landsat mean that the color variation of individual lava flows can be especially helpful for interpreting different phases of volcanic activity.
Many of the bright spots within the darker colored basalt flows are sand-filled craters associated with individual volcanoes. Other light-colored areas are depressions covered with silt and fine sand.
This image mosaic consists of numerous Landsat 8 scenes acquired in early 2015. Landsat images can be useful to support geologic mapping and studies of large and remote features such as this.
Lake Urmia, located in northwestern Iran, was once one of the largest saltwater lakes in the Middle East. It supports an important seasonal habitat for many species of migrating birds.
In recent years, the lake has diminished dramatically. Water enters Lake Urmia primarily from rainfall and inflowing rivers. The diversion of water from local rivers for agricultural use is one likely cause of Lake Urmia’s decline. Since 1996, drought has further contributed to the lower lake levels. The lake now covers about 10 percent of the area it covered in the 1970s.
These Landsat images show the changes to Lake Urmia’s surface area over the past fourteen years. Each image was created by mosaicking several individual Landsat scenes to show the full lake area. From 2000 to 2010, some changes can be seen. In the final image (2014), the entire southern portion of the salty lakebed is now exposed.
Future Landsat imagery will continue to be a useful tool for mapping and monitoring of further changes to Lake Urmia and its surrounding areas.
These two Landsat images show the urban area around Cape Town, South Africa. The more recent image (right) reveals scars from several fires that broke out in early March 2015, and were intensified by strong winds and hot summer temperatures.
The dark fire scar on the left side of the March 11 image is from a fire that had started ten days earlier and burned more than 5,000 hectares (12,000 acres). The dark scar on the right side of the same image is from the Jonkershoek Fire, which started March 9 and was still active at the time this image was collected. About 4,000 hectares (10,000 acres) were burned before this second fire was contained.
Landsat imagery is a valuable tool for the mapping and measurement of burned extent and lost vegetation due to wildfires. As the landscape begins to recover, Landsat will also be useful for monitoring the area’s regrowth and restoration.
Agricultural Land Use along the Chira River, Peru March 20, 2015
These two Landsat images show the expansion of agricultural fields along the Chira River in northern Peru. The green of irrigated fields contrasts against the arid background of the land in this coastal region. The main crops in this region include rice, cotton, maize, mangoes, and lemons.
The new agricultural areas in the second image (2014) are supported by irrigation from the Chira River and Poechos Reservoir in the upper right portion of the images. The reservoir and its system of dams were developed to generate electricity, control flooding, and support local irrigation needs.
Landsat imagery is often used to monitor the status and changes of agricultural land use and water resources over time.
New Land Forming in the Atchafalaya Basin March 6, 2015
Most of the Mississippi River Delta in southern Louisiana is sinking. An area almost the size of Delaware has been lost to subsidence over the past 80 years. However, further west along the coastline is an area of delta buildup.
These two Landsat images show changes to the coastline along the Atchafalaya River outlets between 1984 and 2014. Sediments carried by the Atchafalaya River, a distributary of the Mississippi, are responsible for the growth of two new river deltas seen in the 2014 image. These two deltas are from the main Atchafalaya River (right) and its associated Wax Lake Outlet (left). Both of these channels were used for flood control during the Mississippi River floods of 2012, when water was diverted from the Mississippi through the Atchafalaya River Basin into the Gulf of Mexico.
The slow-moving waters of the Atchafalaya River allow suspended sediments to settle near shore. This creates an optimal land- and marsh-building environment. In contrast, the lower Mississippi River’s waters flow quickly through a narrow channel, carrying most of its suspended sediments far offshore. The coastal marshland that has now been built in the Atchafalaya region gives planners hope that other areas of the Mississippi Delta could be similarly rebuilt or preserved through land and water management.
The continuous acquisition of Landsat imagery now spans more than four decades, providing a valuable historical record that can help researchers and scientists monitor and understand landform changes on the Earth’s surface.
These two Landsat images show several of Iceland’s ice caps as they appeared in September 1986 and 2014.
The largest white area is the Mýrdalsjökull Ice Cap. Underneath this massive mound of ice sits the active Katla volcano. Katla erupts every 40–80 years and is accompanied by high-volume glacial outburst floods (jökulhlaups). The smaller ice cap to the west is Eyjafjallajökull. This ice cap also covers an active volcano, which last erupted in 2010 and disrupted air travel for several weeks.
The brown areas on both ice caps consist of accumulated volcanic ash and other deposits from past volcanic eruptions. The dark cover of volcanic ash from the 2010 eruption is especially prominent on the 2014 image of Eyjafjallajökull.
At first glance, there appears to be remarkable shrinkage of the ice caps by 2014, the situation for most of Iceland’s ice cover. However, the bright white areas in the 1986 image represent fresh snow cover, which is not present in the 2014 image. To monitor the actual changes in the extent of an ice cap, scientists measure changes in the position of the terminus of outlet glaciers.
Landsat is one of several important remote sensing tools being used by glaciologists to map and monitor changes in the Earth’s ice cover over time.
Chesapeake Bay: A Landsat 8 Surface Reflectance Mosaic February 12, 2015
Chesapeake Bay is the Nation’s largest estuary and its restoration and protection is a priority. The USGS provides scientific information to help manage this vital ecosystem. As part of that role, staff at the USGS Earth Resources Observation and Science (EROS) Center created this true color composite image. The image was created using Provisional Surface Reflectance data from five Landsat 8 scenes, acquired in October and November 2014.
Provisional Surface Reflectance processing includes atmospheric correction to reduce haze, aerosol, water vapor, and ozone effects from Landsat Level 1 processed data. The enhanced processing makes this seamless mosaic possible and provides a sharper view of the Earth’s surface, as if there were no atmosphere interrupting the view between the satellite and ground.
Chesapeake Bay is the dark shape stretching up through the center of the image. Sediment in the water appears either light blue or green. Baltimore, Maryland, and Washington, DC, are the two bright areas near the upper left. The peninsula across the Chesapeake from these cities is a patchwork of farm, forest, and protected areas.
Moving water holds potential for generating electricity, and hydroelectric power currently generates over 16 percent of the world’s electricity.
These Landsat images show the site of the Three Gorges Dam in China, which is the largest hydroelectric dam in the world. The dam is over 2,300 meters (1.4 miles) long and forms the straight line across the river in the second image. The project became fully operational in 2012 and has a power generation capacity of 22,500 megawatts. The reservoir created behind the dam stretches 600 kilometers (373 miles) along the Yangtze River and provides water storage for downstream flood control along with electric power.
The Landsat image from 1993 (left) shows the area one year before construction began. The 2013 image (right) was acquired one year after the power plant became fully operational. The second image shows the reservoir created by the dam and the higher water level that now extends into many side valleys. Also visible in the 2013 image is a lock system that supports shipping traffic, as the increased depth and width of the river now permit larger ships to travel this area.
As hydroelectric power continues to expand around the world, Landsat imagery can help monitor the land surface changes and impacts caused by these projects.
The Topaz Solar Farm is one of the largest solar farms in the United States. Located in central California, the 550-megawatt power station consists of 9 million solar panels across 9.5 square miles (24.6 square kilometers). Construction began in 2012 and was completed in late 2014, and the site can now produce enough electricity to power 160,000 homes.
These images, acquired by Landsat 7 and Landsat 8, show the area of the solar farm development. The 2011 image was acquired before construction started and shows that the previous land use was agriculture. The 2015 image shows the completed project. In the second image, the agricultural land use (green blocks) has been replaced by the solar installation (dark blocks). This second image also shows less overall greenness, due to seasonal change.
Landsat images such as these can help document changes to the landscape, as alternative power sources are being developed to provide renewable energy for the Earth’s growing population.
Wind Power in Texas, United States January 20, 2015
Wind power is produced by using large generators to harness the kinetic energy of wind. It is gaining importance as a large-scale source of renewable energy, and new wind farms are being developed worldwide.
In the Texas Panhandle of the United States, an area previously known for fossil fuel production is undergoing a rapid surge in wind energy development. One example is the Longhorn North Wind Project, which was initiated in late 2013 and expected to be fully operational in 2015. When completed, the installation will provide approximately 200 megawatts of power from 100 wind turbines. The area covers almost 57 square kilometers (22 square miles), and is only one of many new wind farms that are being developed in this region of Texas.
These two images show the Longhorn North Wind Project area in December 2013 and one year later in December 2014. The irregular white lines in the later image are access roadways that support construction of the new wind turbines and connection to major transmission networks in the area. The small bright dots on those roadways represent individual turbine locations.
Another change in the later image is an increased number of green fields and small lakes filled with water. In September 2014, remnants from a tropical storm brought heavy rain to this part of Texas, which had been in a drought since 2011.
As wind energy sources continue to expand in the United States and worldwide, Landsat imagery will be useful for monitoring the land changes associated with this development. The consistent, repetitive images from Landsat can also provide a valuable record of the weather- and climate-induced influences as they occur on the Earth’s landscape.
The Sampson Flat Fire started on January 2, 2015 near Adelaide, Australia. Hot, windy weather during the Australian summer caused the bushfire to spread quickly and move erratically. By January 7, it had burned over 120 square kilometers (46 square miles) of woodland and grassland within the steep and inaccessible terrain of the Mount Lofty Ranges.
In the Landsat 8 image acquired on January 4, the burned areas are brown. Active fire appears red with white-blue smoke rising from it. The urban area of Adelaide can be seen in the lower left.
As of January 9, the fire has been contained, but firefighters continue to monitor the unburned pockets of vegetation for flare-ups. Falling trees and limbs have become a hazard for crews working in the area.
Multiple Storms along the Vietnam Coastline December 23, 2014
In July 2014, rains from Typhoon Rammasun triggered heavy flooding as it made landfall in northern Vietnam. Only two months later, Typhoon Kalmaegi made landfall along the same section of coast. While the rainfall was not as strong as it was from Rammasun, rivers were still swollen from the previous storm.
The first two Landsat images show the shoreline along the Gulf of Tonkin after each of these major storms. In the July image, the dark shades across the landscape indicate the extent of flooded land and potential crop damage due to Typhoon Rammasun. Increased flows of river sediment into the gulf are prominent in this image; bright shades of blue contrast with the surrounding waters.
The second image was acquired several days after Typhoon Kalmaegi made landfall. This image shows a less pronounced flood impact across the landscape, but sediment flows are still clearly visible from this storm. The October image shows the area in continued recovery after both typhoons, with normalized sediment flows into the gulf.
Landsat data provide an important source of pre- and post-event images that are often used to support disaster and recovery monitoring worldwide.
Ohio’s capital city, Columbus, is situated along the Scioto River and is one of the fastest growing cities in the state. In 1986, the municipal population was estimated at 600,000. The latest population estimate for Columbus from the U.S. Census Bureau is over 820,000.
These two images show Columbus and surrounding areas in 1986 and again in 2014. The second image shows the gray urban areas expanding into previous agricultural land, which is indicated by green patchy areas. The bright areas throughout the city are retail and industrial centers. The dark blue spots along the river in the southern part of the city are wastewater treatment ponds and other ponds associated with local sand and gravel quarries.
The historical record provided by Landsat images can be a useful tool for city managers, planners, and scientists who are monitoring and documenting the changes to Earth’s land cover caused by urban expansion.
A volcanic eruption that started on August 31 in Iceland shows no sign of weakening. This eruption is occurring at the Bardarbunga volcano, which lies north of the Vatnajökull glacier in south-central Iceland. Lava has been flowing spectacularly from the Holuhraun lava field, and the eruptive fissure has now spread lava across more than 70 square kilometers (27 square miles).
These Landsat 8 images show different spectral bands and band combinations acquired on September 6, 2014. These images provide examples of the type of information being used by scientists to monitor and map the eruption.
The first image is a false-color composite that combines information from the shortwave infrared, near-infrared, and green wavelengths of light. In this image, the recently erupted lava glows bright orange and red. The areas covered by snow and ice within the neighboring glacier can also be seen in shades of blue-green. The second image is a natural color representation, based on the visible wavelengths of light. In this image, the location of active volcanic fissures can be seen as small bright features, and the plumes and trajectory of ash and steam can also be clearly seen. The surface of the cooling lava flows (where visible) are black. The third image is a thermal infrared representation. This image shows relative surface temperature over the region, with the hottest areas (erupted lava) shown in bright hues and colder areas (glacial ice and water bodies) shown in dark tones.
The combined information available in Landsat images can provide an important complement to ground sensors. These images are important for scientists and decision makers engaged in mapping and monitoring the eruption.
As 2014 comes to an end, so does the growing season in the northern U.S. heartland. Millions of acres of corn, soybeans, alfalfa, and small grains have been harvested from the land in recent weeks.
These two Landsat images show the harvest activity and seasonal vegetation changes along the Platte River in south-central Nebraska. The river flows from the northwest corner of the images and then to the east, and its associated basin provides an important corridor for agriculture. The first image was acquired in early September. This image shows many actively growing fields (green blocks) across the landscape, especially within the Platte River basin. The second image (late October) is dominated by shades of tan, pink, and gray. These colors indicate bare ground, and only a small number of green fields remain.
Landsat data are often used for agriculture monitoring and management. This imagery can help users monitor local and regional conditions of the world’s croplands—within a growing season, from year to year, and from one decade to another.
Over 20 Million Landsat Scenes Downloaded October 29, 2014
Since 2008, all Landsat data—archived and newly acquired—have been available for free download. On September 16, 2014, users worldwide downloaded over 14,000 scenes from the servers at the USGS Earth Resources Observation and Science (EROS) Center. These downloads brought the total number of Landsat data downloads to more than 20 million.
This Landsat 8 scene was one of the many downloaded on September 16. It shows the area around Juneau, Alaska. Water is dark and includes Lynn Canal, the long water body in the middle of the image. Green is vegetation and forested mountain areas.
This image also provides a clear view of the Juneau Icefield. Several glaciers flow from this icefield, and glaciologists are using the 42-year Landsat archive to monitor the advance and retreat of the glaciers over time. Since Landsat 7 and Landsat 8 together provide an 8-day repeat cycle, Landsat can be an important supplement to ground-based glacier monitoring.
Scientists, students, city planners, environmental engineers, and many others have been able to use the vast archive of Landsat data free of charge to support and enhance their research. The free availability of Landsat data enables scientists to conduct large-scale global studies that would otherwise be too costly.
Urban Growth of Maracaibo, Venezuela October 22, 2014
The city of Maracaibo, Venezuela, is located on the western shore of a strait that connects Lake Maracaibo to the Gulf of Venezuela. The region is an important source of oil production for Venezuela, and Maracaibo serves as a major port for shipments of oil. This area is also known for its commercial fisheries, shrimp farming, and salt production.
These two Landsat images show the urban expansion of the city of Maracaibo between 1986 and 2014. Cities along the lake to the east and south have also grown.
The 40-year archive of Landsat data is useful for studying many types of change across the Earth’s surface, including changes due to urban growth, agricultural activities, and coastal land use.
The Huang He (Yellow) River in China is the most sediment-filled river on Earth. It flows from the Bayan Har Mountains to the Bohai Sea. Along the way, it crosses a soft plateau that is covered with fine, wind-blown soil. The river carries away millions of tons of this delta-building material every year. Over time, the river carries its sediment load farther outward into the sea. These Landsat images provide a view of the dramatic changes to the shoreline.
Besides changes to the delta, aquaculture has significantly expanded along the coastline near the river delta, as well as farther south along Laizhou Bay. The dark geometric shapes along the coast were built on what were once tidal flats. These ponds hold shrimp and other types of seafood.
Landsat imagery is useful in providing historical records of the changes taking place on the Earth’s surface, and future acquisitions will allow scientists to help in protecting the delta’s natural wetlands, while meeting the demands of development along the shoreline.
As a 3-year drought continues in the western United States, water levels have been dropping in many California reservoirs, leading to emergency water use restrictions across the state.
These two Landsat images show the changing shoreline of Shasta Lake reservoir in northern California over the past three years. The first image was collected in September 2011 and shows the shoreline when the reservoir’s water levels were at 77 percent of total capacity. The tan colors in the September 2014 image show the change in shoreline. Even though snowmelt slightly increased the lake level earlier in 2014, the reservoir was still at only 27 percent capacity when this more recent image was acquired.
The lower right portion of the second image also shows a recent burn scar from the Gulch Fire. This fire was officially contained one day before the September 17 image was collected.
The images collected by Landsat are an important tool for monitoring changes to the earth’s surface, and can help support analysis related to water resources and other environmental conditions for affected communities.
Mapping Biodiverse Highlands with Satellite Imagery and Advanced Elevation Data September 23, 2014
A team from the USGS Earth Resources Observation and Science (EROS) Center produced a detailed land use/land cover map using Landsat satellite and 30-meter elevation data from the Shuttle Radar Topography Mission (SRTM) of the highlands along the Senegal-Guinea border. The Dindefelo Nature Reserve was created to protect the high biodiversity of this area, including chimpanzee habitat, which is closely correlated with topography. The map helps scientists visualize the resources within the reserve and the mounting human pressure on the natural landscapes that surround it.
The Landsat 8 image (left) of the study area coupled with the SRTM 30-meter data (center) provides a specialized view of the topography. The land cover map (right) shows the diverse habitats, including the locations of gallery forests. These narrow ribbons of dense trees follow watercourses and are indicated as purple shades on the land cover map. Gallery forests provide critical refuge for many species of plants and animals during the long, hot dry season. The maps are being used in a proposal by the Jane Goodall Institute to Senegal and Guinea to extend the Dindefelo Nature Reserve south into the Guinea highlands.
Mapping these biodiverse highlands is one example that demonstrates the advantage of the more accurate elevation data from SRTM. For more information, see the USGS Top Story here.
Detailed Elevation Data—Niger River Delta September 23, 2014
Shuttle Radar Topography Mission (SRTM) data had previously only been available worldwide at 90-meter resolution. The National Geospatial-Intelligence Agency (NGA), NASA, and USGS are now releasing a newly processed, global SRTM 30-meter dataset.
The above images show an example of the difference between the 90-meter and 30-meter data of the Niger River Delta in western Africa. The Landsat image, also at 30-meter resolution, of the same area shows the extensive coastal estuaries, tidal flats, mangrove forests, and lowland rainforests of this part of southern Nigeria. More detailed elevation data are especially critical in such coastal settings that have small elevation changes.
For more information on the new SRTM elevation product, see the USGS Top Story here.
Coastal Flooding near Semarang City, Indonesia September 19, 2014
Coastal inundation is an ongoing concern for the region near Semarang, Indonesia. This area faces several different types of flood risk, due to the potential combination of high tides, seasonal rainfall events, and river flooding. Much of this low-lying area is only 0–25 meters above sea level, and in some areas, land subsidence has also been occurring for many years. All of these factors lead to a risk of coastal flooding for local populations.
These Landsat images indicate changes in the area near Semarang City over the past 20 years. Semarang City is located at the bottom center of these images, and the differences along the coastline are particularly visible northeast of the city. In particular, the 2014 image shows coastal inundation that is encroaching on populated areas, roads, and structures.
Disaster managers and risk reduction personnel rely on satellite imagery such as Landsat to help document and mitigate flood threats as effectively as possible. The 42-year archive of Landsat imagery also provides a historical record that can be used to indicate long-term changes as they occur in coastal areas. This can help scientists and engineers understand and analyze historical trends, and assist with future planning for flood management and mitigation.
The Zapata Peninsula is located in western Cuba. Most of this sparsely populated area lies within the Ciénaga de Zapata National Park and UNESCO-designated Biosphere Reserve.
The region is covered by large areas of open swamp and marshes intermixed with dense woodlands. It is also home to one of the largest coastal wetlands in the Caribbean region. The extensive and fragile ecosystem is protected for its biodiversity and high concentration of migratory birds, mangrove forests, seagrass beds, and coral reefs.
This Landsat 8 image shows the peninsula and neighboring region. The dense forests are dark green, while the open swamps and marshlands are shown in brighter green and yellow tones. This image also shows the surrounding deep ocean water and channels (dark blue and black), along with shallow water and coral reefs (bright blue).
Landsat images provide a valuable record of the earth’s surface and are useful for space-based mapping and classifications of vegetation, ecosystems, and coastal habitats.
Mount Tavurvur erupted on August 29, 2014, sending ash over surrounding areas on Papua New Guinea’s New Britain Island. The stratovolcano is located along the eastern edge of the Rabaul Volcanic Complex, and its last major eruption was in 1994.
These two Landsat images were acquired in April and September 2014. In both images, Mount Tavurvur can be seen to the east side of Simpson Harbor. This harbor forms part of the much larger (mostly submerged) Rabaul Caldera.
The second image was acquired a few days after the August 2014 eruption. This image shows the extent of ashfall (gray-brown), while the forested areas that were less affected by ash remain green.
Images acquired by the Landsat satellites are useful for monitoring land changes and recovery after natural disasters such as volcanoes.
Oil Production near Tioga, North Dakota August 28, 2014
These Landsat images show the area around Tioga, North Dakota, in 2002 and again in 2014. Oil was first discovered near Tioga in 1951, and the town has experienced several episodes of rapid growth due to its location over the Williston Basin, a major North American geologic source of oil, natural gas, and other energy resources. The recent development of advanced drilling techniques has led to a new surge of production, particularly within the Bakken Formation, which has become an important source of oil within the United States.
These two Landsat images show the dramatic changes to the landscape near Tioga in recent years. Many new oil wells and related facilities (small bright features) are visible in the 2014 image compared to the earlier image. The rapid expansion of the town of Tioga can also be seen, as the town has grown to support an expanding workforce. The 2014 image also shows the development of new oil processing and transportation facilities along the western and eastern edges of Tioga.
The images from the Landsat archive span four decades and provide a consistent worldwide record of land use and land cover changes as they occur across the Earth’s surface.
Urban Expansion of Shenyang, China August 22, 2014
The city of Shenyang is one of the largest cities in northeastern China. Situated along the Hun River, the city is a major transportation hub. It is also an important industrial center, representing the core city of the Shenyang Economic Zone. Its urban and outlying areas are home to over 8 million people.
These images show the city of Shenyang in 1984, and again in 2014. The expansion of Shenyang’s urban area over the past 30 years is striking, as the urban developed area (shades of silver and gray) has expanded into the previous farmland and forested areas (green shades) surrounding the city. The large green feature in the north-central part of the urban area is Beiling Park, the largest park in the city.
The 40+ year archive of Landsat imagery provides a valuable tool for recording urban growth and other types of land cover change over time. The information in these images can also be useful for monitoring the effects of urban growth on the surrounding landscape and ecosystems.
Dam Breach at Mount Polley Mine, Canada August 13, 2014
On August 4, 2014, an earthen dam failed at the Mount Polley Mine in central British Columbia, Canada. The dam had been built to hold a tailings pond that contained water and waste materials from local gold and copper mining operations.
The tailings pond covered over 4 square kilometers and within a few days, millions of cubic meters of wastewater and slurry had flowed from the pond into neighboring Polley Lake, Hazeltine Creek, and Quesnel Lake.
These two Landsat images show the area of active mining and associated tailings pond. In both images, the dark areas indicate clear water. The suspended materials within the tailings pond (first image) are more reflective, so this water appears brighter. In the August 6 image, the waste materials from the tailings pond can be seen (blue, green, and silver) flowing down Hazeltine Creek and into the two nearby lakes.
Algae blooms commonly happen in summer on Lake Erie, but the blooms have been increasing in recent years. This year, north winds pushed the algae toward the water intake system for Toledo, Ohio, the urban area visible in the lower left of these Landsat 8 images.
Certain types of freshwater algae produce a toxin that can be harmful to people. Whether harmful or not, algae blooms are often large enough to appear in satellite images. This Lake Erie bloom shows up as green swirls on the surface of the water in the August 1 image. The white spots above the land and water are clouds. The June 14 image is displayed for comparison.
Scientists often use satellite imagery (such as Landsat) along with aerial imagery and water-based sensors to monitor the algae blooms each summer. The information helps them determine the type and distribution of the algae. Furthermore, comparing the annual extent of the blooms helps scientists monitor long-term trends and predict the impacts and movement of future algae bloom events.
Heavy rains starting in June have brought the worst flooding the country of Paraguay has ever seen. Thousands of residents have been displaced due to flooding of the urban and rural areas along the Paraguay River in this central South American country.
These images, acquired by Landsat 8 on April 14, 2014, and July 19, 2014, show the Paraguay River, north of the city of Asuncion. The April image shows the area before the flooding began. The July image shows the dramatic change due to the flooding.
Future Landsat data acquisitions will be useful in monitoring the affected areas.
The Bone Valley region in Central Florida contains the largest known deposits of phosphate in the United States. These deposits were formed within layers of fossil-rich sediments that developed millions of years ago when the area was underwater. The rocks in this region contain phosphate minerals that are broken down for phosphorus, which is used to produce agricultural fertilizer and other applications.
These Landsat images show an area with phosphate mining activity in 1986 and again in 2014. The two images show numerous changes to the landscape during this time interval. The surface mining process involves removal of the vegetation and top layers. The exposed phosphate ore is removed and scooped into a pit, then mixed with water to create “slurry”. The slurry is pumped to a processing plant where the phosphate is extracted. After processing, the remaining waste by-products are pumped into settling ponds, and the land undergoes a reclamation process.
The multiple stages of this process are apparent in these Landsat images. The bright areas indicate exposed rock and land surface. The black, blue, and purple tones indicate water combined with other components in varying compositions, within the slurry and settling ponds. The green shapes with geometric outlines (particularly toward the center of the second image) indicate reclaimed areas with new vegetation.
Dry conditions have made this year another busy one for wildfires in the western United States. For example, responders in east-central Oregon are currently fighting several separate fires that were started by lightning near Malheur Lake on July 14, 2014. The combination of high winds, low humidity, and high temperatures has been making the firefighting work difficult.
These Landsat images were acquired on July 1, 2014 (left), and again on July 17, 2014. Malheur Lake is in the center of both images. The large fire scars visible in the second image show the area burned within the Buzzard Complex as of July 17. The bright orange areas also show where the fires were continuing to burn at the time the second image was collected.
Landsat imagery can be an important tool to help evaluate the areas damaged and destroyed by fire, and can assist in response planning and identifying areas of further risk. Future images from Landsat will also be helpful for monitoring the land recovery after major fires such as this.
2014 World Cup—Rio de Janeiro, Brazil July 11, 2014
The 2014 Fédération Internationale de Football Association (FIFA) World Cup began on June 12, 2014, and has been taking place at numerous venues across Brazil. The final match is on Sunday, July 13, at the Maracanã Stadium in Rio de Janeiro.
This Landsat 7 image was acquired on June 26, 2014. The main image shows the spectacular setting of the city of Rio, with its high mountains, islands, and famous long beaches that follow the coastline. The smaller image shows the location of the stadium (white circle) where the 2014 World Cup final match will take place.
These “pan-sharpened” images use Landsat’s panchromatic band (15-m resolution) in combination with the 3-band multispectral information (30-meter resolution). This technique is often used by scientists and analysts when it is necessary to show more details within the Landsat image than would be visible using the multispectral information alone.
These Landsat image products were created using hundreds of individual Landsat scenes. The images have been mosaicked and “draped” over elevation data to show the topography and landscapes across the United States.
The main image shows the Rocky Mountains and other mountain ranges that dominate the western United States. The central portion of the image consists mainly of rolling plains and farmland. The right portion of the main image shows the mountain ranges and coastal plains that make up the eastern U.S. seaboard. The Alaska and Hawaii mosaics show the predominant features of those landscapes as well.
An individual Landsat state mosaic has been prepared for every one of the 50 U.S. states plus Puerto Rico. All of the Landsat image mosaics are available in poster-ready format and may be viewed and downloaded via the USGS Earth Resources Observation and Science (EROS) Center Image Gallery (http://eros.usgs.gov/imagegallery/landsat-state-mosaics).
The imagery that is collected by the Landsat satellites can be useful for general visualization of large areas and landscapes, and is often used in combination with other datasets (such as elevation) to create image products such as these.
Flooding in Southeastern South Dakota June 27, 2014
In June 2014, southeastern South Dakota received record amounts of rainfall, and parts of neighboring states also received excessive rainfall due to a series of severe storms. As rivers overran their banks, many roadways became impassable and the rising waters damaged many homes and businesses. This area is an important agricultural region, and the heavy rainfall and accompanying hail damaged many of the recently planted corn and soybean crops.
The second image clearly shows the Vermillion River and the Big Sioux River flooded over their banks. The lower right corner of the second image also has darker tones mixed throughout the agricultural areas (bright green). These darker tones suggest potential flood damage to the crops in this region.
Landsat images such as these can be an important tool for evaluating the damage to local crops and for monitoring the agricultural recovery and replanting efforts on a regional scale. The Landsat imagery will also be useful for monitoring the overall distribution oft floodwaters as they recede and move downstream.
28 Years of Landscape Change in Texas, USA June 23, 2014
These images show a portion of the Texas Panhandle where it meets the western border of Oklahoma. The area is part of the “Granite Wash” region, which contains over 3,600 wells that mine oil and natural gas from as deep as 17,000 feet (5,182 meters) underground.
When comparing Landsat imagery from 1986 (left) and 2014 (right), many changes can be seen on the landscape. The large number of white spots in the second image indicates an overall increase in the number of oil wells. The reduced overall greenness (vegetation) in the second image was caused by several recent years of drought. Other visible changes include additional center-pivot irrigation systems (dark circles). There are also several new burn scars from wildfires that occurred in March 2014.
As the Landsat archive grows, its imagery can be used to record and monitor many different types of landscape changes through time.
The Funny River Fire was first discovered on May 19, 2014. By early June, it had burned almost 200,000 acres in south-central Alaska, including much of the Kenai National Wildlife Refuge.
The Landsat 8 image on May 4 shows the area before the fire began. Heavy smoke covers the Kenai Peninsula in the May 20 image, and this image also shows some of the areas of active burning (bright orange) along the edges of the wildfire area. On June 5, Landsat 8 captured the total extent of the burned area.
A series of wildfires erupted along the coastal region north of San Diego, California, in mid-May 2014. The first wildfire (Bernardo Fire) began on May 13, followed by several additional fires that occurred over the following days. At one point, firefighters were battling at least eight active wildfires and over 175,000 evacuation notices were issued.
The Landsat 8 image (left) was acquired on May 9, 2014, and shows the area before the fires began. The Landsat 7 image (right) was acquired eight days later. The red tones show numerous areas that were burned as of May 17, 2014.
The repetitive imagery provided by the Landsat satellites allows officials to evaluate the destructive impacts and monitor future recovery after disaster events such as these wildfires.
A tornado that touched down in central Arkansas on April 27, 2014, proved devastating and deadly.
These Landsat images show the area northwest of Little Rock, Arkansas, before and after the storm. The path of the tornado can be seen in the May 1, 2014 image. The tornado began southwest of Lake Maumelle, before crossing the Arkansas River and moving through the town of Mayflower. It then continued to the northeast through the town of Vilonia.
Landsat image acquisitions will be useful for monitoring the current impacts and future recovery of vegetation destroyed in the storm.
Winter Ice Cover, Lake Superior (USA/Canada) May 8, 2014
The extreme cold of the 2013-2014 winter season created historic ice cover on the North American Great Lakes and much slower than normal spring melt. The persistent and widespread ice has affected shipping transportation throughout the Great Lakes region. At one point, the Lake Superior ice cover was estimated to be nearly 95% with an average thickness of 22.6 centimeters (8.9 inches). Pressure ridges and ice motion can also cause plates of ice to buckle and stack, creating local ridges up to 1.5 meters (5 feet) thick in some places. Even though the ice has now started to melt, some areas of this year’s ice cover could last into June.
The abnormal thickness and extent of this year’s ice cover caused challenges to the ice breakers that allow shipping to and from ports such as Duluth Harbor. When cutting through very thick ice, it can take many hours to go a very short distance. At one point, as many as 70 ships were awaiting entry into Lake Superior, and the ships were being grouped together as escorted convoys to maximize ice-breaking efforts and allow safe passage.
These three Landsat 8 ”natural-color” (3-band composite) images show the Lake Superior area north of Duluth, Minnesota, in February and April 2014. The first image (February 16) shows the ice cover near its maximum. The second image (April 5) shows reduced ice coverage, along with an ice breaker channel that was created to allow ships to enter Duluth Harbor. The third image shows the remaining ice cover as of April 21.
Landsat imagery provides a consistent and repetitive view of the Earth’s surface and can be used to help monitor changing conditions over time.
Drought Conditions in California, USA April 24, 2014
After several consecutive years of below-normal precipitation, the U.S. state of California is preparing for its most severe drought emergency in decades. The current drought is due in part to decreased rainfall along with reduced winter snowpack in the Sierra Nevada mountain range. In 2013, California received less precipitation than any other year since it became a state in 1850. Water conservation efforts 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. Because of its geologic age and geographic isolation, more than 80 percent of the lake’s freshwater species are found only at Lake Baikal.
A narrow sand spit stretches across the lake’s north end to form Yarki Island, which separates the northernmost shoreline from the open water. This long, discontinuous land surface is the result of accumulated sediments from several rivers flowing in from the north, combined with the interaction of these sediments with incoming waves, wind, and storms from the main lake to the south. The shallow lagoon that is created behind Yarki Island is filled with relatively warm waters and peat deposits, and forms an important bird sanctuary.
This Landsat image shows the area around Yarki Island and northernmost Lake Baikal. The green tones in the lagoon area depict vegetative sediments. The mouth of the Verkhnaya Angara River can be seen on the right side of the image.
The vast archive of Landsat images helps researchers and scientists monitor the Earth’s ecosystems, and provides unbiased evidence of how changes can affect these ecosystems worldwide.
Near the southernmost tip of Africa lies the Sundays River Valley, an agricultural area rich in citrus fruit production. Urban settlements and orchards in the subtropical climate are aided by a well-developed irrigation system that was established in the early 1920s with the construction of a dam upstream of the area shown in these images.
These Landsat images show the Sundays River Valley area in November 1986, and again the same month in 2013. Orchards can be seen expanding along both sides of this stretch of river. The bright green colors indicate orchards and agricultural lands, and pinkish hues indicate unused parcels.
Landsat imagery is valuable for measuring and monitoring land use and land use changes across the Earth’s landscape.
These Landsat images show portions of the Cordoba and San Luis provinces in central Argentina. The urban area to the right of image center is Villa Dolores. To the north and east of the urban area, the Embalse Allende (“Vineyard Dam”) can be seen in the two images.
This region has been long noted as an important center for potato production. In this semiarid climate, a double crop is possible when the potatoes are given enough moisture through irrigation. Other important local crops include wine grapes, olives, tobacco, walnuts, and jojoba.
These two images show 20 years of change to the agricultural landscape. The first image was acquired in January 1994 and shows areas of active cropland (bright green and lighter tones). The second image, from January 2014, shows apparent conversion of additional areas to agricultural use. The bright green circles indicate center pivot irrigation systems, which have been installed over the past two decades.
Since both images were acquired during the same time of year (mid-January) the overall difference in color tones also suggests a difference in weather conditions between the two years. The 1994 image (green) was likely a year of higher precipitation, compared to the 2014 image (brown) which has been relatively dry.
Landsat imagery is an important tool for monitoring change to the Earth’s landscape over time.
32 Years of Change: Incheon, South Korea February 25, 2014
The shoreline area of Incheon, South Korea, has been changing dramatically over the past 32 years, as depicted by these Landsat images acquired in 1981 and again in 2013. Previous marsh areas have been turned into usable land through land reclamation. Urban growth has also expanded.
In the center of these images, previously separate islands have been joined together as reclaimed land to become home to Incheon International Airport. The airport opened in 2001 and is now one of the largest and busiest in the world. The new Incheon Bridge (also called the Incheon Grand Bridge) can also be seen in the second image; it opened in October 2009.
The Landsat archive contains 40 years of data, which allows users to see changes as they are occurring throughout the Earth’s landscape.
On January 15, 2014, lightning sparked a brushfire in Grampians National Park in the State of Victoria in southeastern Australia. The combination of dry, hot weather and strong winds contributed to a rapidly spreading complex. The fire became so intense it created a 12-km (7.5-mi) wide convection column that created its own weather, generated lightning strikes, and sparked many smaller spot fires.
Residents of the town of Halls Gap, just south of the burned area, were evacuated. The fire claimed at least one life and scorched over 53,000 hectares (131,000 acres) before it was contained on January 21.
These two Landsat 8 images show the area on January 12, 2014 (before the start of the fires) and again on January 28, 2014. The dark tones in the later image depict the burned areas.
The information contained in Landsat images is useful for mapping wildfires, along with many other types of land cover change.
Effects of Flooding: Hyères, France February 7, 2014
In mid-January 2014, unusually heavy rains in southeast France led to flooding, landslides, and evacuations. In some areas, up to 20 centimeters (8 inches) of rainfall occurred over three days, far exceeding the typical monthly totals.
These Landsat 8 images show the area around Hyères, along with the Giens Peninsula (Presqu’île de Giens) and nearby islands.
The two images were acquired on January 15, 2014 (one day before the rains began) and again on January 31, 2014. The bright blue colors in the right image show the flow of the sediment-rich floodwaters as they moved out into the Mediterranean Sea.
Gaborone is the capital and largest city in Botswana. Its current residential population is estimated at 250,000 within the city limits (450,000 when including the outlying areas).
Almost all of this urban development has occurred within the last 50 years. Development of initial infrastructure began in 1963, and the city was formally established in 1966 on the eve of Botswana’s independence. Since that time, Gaborone has experienced rapid urban growth. This expansion is expected to continue as economic and commercial entities become further established there.
The Gaborone Dam, south of the city, was completed in 1964 and provides critical water supply for the growing city. Within the last decade, the water levels have dropped significantly due to increasing water usage along with climate factors. In the early 2000s, the reservoir was estimated to be 80 percent full; as of December 2013, the water level of the reservoir reached its lowest point since the dam was built, at approximately 13 percent full.
These Landsat images show the city of Gaborone and the surrounding area in 2001 and again in 2013. These images show the urban growth (gray) extending into the landscape in the later image. The images also show the reduction in size of the reservoir over the past 12 years.
As urban populations continue to grow, the changing landscape and water resource management become important issues for community leaders. Landsat imagery provides repetitive views of the Earth’s surface which can help monitor urban growth patterns and other changes to Earth’s resources.
Cuesta del Viento Reservoir, Argentina January 24, 2014
The Cuesta del Viento (Wind Slope) Reservoir formed behind a large dam that was constructed on the Jáchal River in 1997–1998 in the San Juan Province of Argentina.
Surrounded by spectacular mountains, the reservoir controls the flow of streams from snowmelt of the Andes Mountains and provides a source of irrigation for fruit plantations and other crops. The reservoir has also become a popular destination for windsurfing and kitesurfing because of the consistent afternoon winds that reach 30–40 knots (55–74 km/hour; 34–46 mi/hour). These powerful winds are caused by the daily flow of air currents that travel out of the eastern Andes Mountains and converge in the river valley.
These Landsat images show the area in November 1996 (before the dam was built) and December 2013. The inclusion of Landsat’s shortwave infrared band information for this image pair also highlights the geologic features of the area.
Landsat images provide an unbiased view of features on the Earth’s surface and the changes that take place on the landscape.
Bear Glacier is located on the Kenai Peninsula near Seward, Alaska.
This glacier represents one of over 30 glacial outflows for the nearby Harding Icefield, which covers over 700 square miles (1,800 square km).
Bear Glacier has been receding dramatically over recent decades, as shown in this series of images. The black and white aerial photograph mosaic was collected in 1950 and shows the glacier extending almost fully across the highlighted region (red outline). The satellite images (color) were acquired by Landsat 4 (1989), Landsat 7 (2001), and Landsat 8 (2013). Taken together, these images show an overall trend of glacial retreat in this area for the 63-year time period.
There are millions of aerial and satellite images held in the USGS archives, which provide important historical and current views of Earth’s changing landscape. These images are public and available for download by anyone for any location worldwide. This glacier represents one of over 30 glacial outflows for the nearby Harding Icefield, which covers over 700 square miles (1,800 square km). Bear Glacier has been receding dramatically over recent decades, as shown in this series of images. The black and white aerial photograph mosaic was collected in 1950 and shows the glacier covering almost the entire area within the highlighted region (red outline). The satellite images (color) were acquired by Landsat 4 (1989), Landsat 7 (2001), and Landsat 8 (2013). Taken together, these images show an overall trend of glacial retreat in this area for the 63-year time period. There are millions of aerial and satellite images held in the USGS archives, which provide important historical and current views of Earth’s changing landscape. These images are public and available for download by anyone for any location worldwide.
Lake Chilwa is a shallow, enclosed saline lake located along the East African Rift Valley in southern Malawi, near its border with Mozambique.
This lake experiences high water level fluctuation, as it is strongly influenced by rainfall and summer evaporation patterns. In recent years, Lake Chilwa has been shrinking. Because the basin is an important source of local rice and fish production, the current drying trend is a potential food security concern.
These Landsat images show the net reduction of lake area between October 1990 and November 2013. The two images also show changes to the extensive wetlands (bright green) that surround Lake Chilwa. These wetlands are internationally recognized as an important seasonal hosting location for migratory birds from the Northern Hemisphere.
Landsat data are extremely useful for scientists and authorities to monitor water resources and land cover changes over time.
Auckland is on the North Island of New Zealand along the Hauraki Gulf. The urban area (purple hues) can be seen on the left side of this image. The round island north of the city that appears darker than the others is a volcanic island (Rangitoto Island) within the Auckland volcanic field.
As one of the few cities in the world to have two harbors on two separate bodies of water, the city has grown to become the largest and most populous in the country. Manukau Harbor is to the southwest of the city and opens into the Tasman Sea. Waitemata Harbor, along the city’s north shores, opens into the Pacific Ocean. On the right side of this image is the Firth of Thames, a bay important for habitat and wetland conservation.
The Landsat 8 Operational Land Imager (OLI) captured this image on September 2, 2013.
The Niigata Prefecture is on the northwest coast of Honshu, Japan’s largest island. Multiple rivers along the shoreline form a fertile coastal plain that supports abundant fields of rice and flowers, both of which are major industries of the area.
The city of Niigata, situated along the coast of the Sea of Japan, is the capital and the most populous city. Due to the low elevation and high annual rainfall, numerous wetlands can be found within the city limits. In fact, Niigata is sometimes called the “City of Water” due to the shoreline location, wetlands, and rivers that flow through it.
Landsat imagery supplies an unbiased view of the Earth’s surface over the past four decades and provides a record of land use, land cover, and change over time.
The city of La Rioja is located on the eastern foothills of the Sierra de Velasco mountain range in northwestern Argentina. The Los Sauces Reservoir and Dam can also be seen to the west of the city.
These Landsat images, acquired in 1984 and 2013, display the urban growth and other changes in the local landscape. With growing population, the city has expanded into the surrounding landscape. Agricultural land use has also increased, as shown in the green and light tan blocks east of the city. The arid climate makes irrigation systems vital to the region’s crops.
The information contained in Landsat imagery helps land managers observe land use and manage hydrological resources.
The large Landsat 8 image shows the full extent of Bangong Lake, which means “long neck swan” in Tibetan. It is located partly in China and partly in the region of Kashmir that is controlled by India. The lake is approximately 155 kilometers (96.3 miles) long from east to west. It reaches only 5 meters (16 feet) wide at its narrowest point.
This lake is unique in that the eastern portion has fresh water, while the waters to the west are saline.
The two smaller Landsat images show the easternmost portion of Bangong Lake. Changes to the local shoreline can be seen by comparing the two images, acquired in 1998 and 2013. During this time period, changing conditions have expanded the lake area, particularly along the marshy southwest and northern shorelines. These shoreline changes can affect the local salinity levels, which in turn may affect the vegetation and biological balance of the area.
The 40-year archive of Landsat imagery is useful in documenting change to the Earth’s landscape.
This image of the Grand Canyon in the southwestern United States is a mosaic of two Landsat 8 scenes acquired October 31 and November 9, 2013. Designated as a national park in 1919, the Grand Canyon has breathtaking views and unique geological formations that attract over 5 million visitors each year. Archaeological artifacts have been found in the park that are nearly 12,000 years old.
Recent high-flow releases of water from the Glen Canyon Dam (northeast of this image) have moved sand along the Colorado River and into the canyon. These sediments are helping to establish sandbars for fish and wildlife habitat and to protect archaeological resources.
The Landsat 8 satellite, launched in February 2013, is providing high-quality worldwide images of the landscape on a daily basis. Landsat serves as a valuable tool for all interested in monitoring the characteristics of the earth’s surface.
Forest Change Portrayed by Landsat Imagery November 22, 2013
On November 15, 2013, a new Global Forest Change survey was released. This online tool shows the forest change that has occurred worldwide from 2000 to 2012, and is based on the global repetitive observations by Landsat satellites during this time period.
These example images show the observed changes in forest cover north and east of Tuscaloosa, Alabama. They also show the change after an EF5 tornado caused massive destruction on April 27, 2011.
The two Landsat images show the forested areas in 2000 and 2011. The tornado path can be clearly seen in the second image.
The derived Global Forest Change map for the same area (right) is based on repeated Landsat observations from 2000 to 2012. Red indicates net forest loss, and blue indicates net forest gain. Magenta indicates mixed activity (gain and loss) within this time interval. Green indicates no change to the forest cover, and black indicates nonforest.
The overall mixed colors in the Global Forest Change map help to record the dynamic nature of the local forest land cover. The red streak clearly shows the forest loss caused by the 2011 tornado.
Agno River Valley flooding, Philippines November 14, 2013
The Agno River is located on the island of Luzon and is the fifth largest river system in the Philippines. Over 2 million people live in the Agno River Valley. The first image was acquired by Landsat 8 in June 2013. The second image (Landsat 7) shows the November 2013 flooding caused by Typhoon Haiyan (Yolanda).
The Landsat satellites collect imagery worldwide on a daily basis, and can help measure and monitor the landscape changes caused by devastating storms.
Boundary Dam Power Station, Saskatchewan November 8, 2013
The coal-fired Boundary Dam Power Station began operations in the early 1960s along the Souris River near Estavan, in Saskatchewan, Canada.
These three Landsat images were acquired in 1972, 1986, and 2013 and show how the landscape has been changing over the years.
The Boundary Dam and Reservoir (near the left-center of the first image) was constructed in 1957 to provide coolant for the coal-fired power station operations. The 1986 image shows expansion of coal mining operations into the surrounding area. The 2013 image shows the Rafferty Dam (upper left), which was developed in the late 1980s and early 1990s to provide additional water for the area and reduce downstream flooding along the Souris River. This image also shows further expansion of the coal mining operations, as well as the emergence of many temporary lakes which began to develop during the wet spring of 2011.
The Landsat archive contains more than 40 years of data that are useful for land change analysis, covering all areas of the globe. Landsat provides scientists and project engineers with invaluable imagery to conduct their research on how the changes affect the landscape.