aller tributaries have also overflowed their banks.
USGS collects streamflow data at streamgages throughout the region, and throughout the United States. These gages measure water levels, streamflow, and rainfall. Along with satellite images, these data help monitor the flooding, and help project the severity of flooding effects downstream.
The Selenga River begins in Mongolia and flows north into Russia where it empties into Lake Baikal, the world’s deepest lake. The river slows as it approaches the lake, dropping large amounts of sediment in a wide alluvial plain. The braided river flows past farm fields—the blocky shapes in the images—and to the lake.
The river forms a unique delta as it carries sediment to Lake Baikal. These Landsat images show the delta in 1989 and 2015. While the overall shape of the delta has not changed significantly, a halo of sand bars surrounds the edge of the delta in the 2015 image. Varying lake levels and the river’s sediment load influence the changing shape of the delta and its sand bars.
Landsat data are freely available to anyone interested in researching and monitoring changes happening to the Earth’s surface.
Brazilian Mining Disaster, Doce River December 16, 2015
On November 5, 2015, a tailings pond dam failed at an iron mine in southeastern Brazil, sending contaminated water sediment through the nearby village of Bento Rodrigues and into tributaries of the Rio Doce (Sweet River). (See http://eros.usgs.gov/imagegallery/image-week-2#Brazil_Images) The sediment from that disaster has since moved downstream to the mouth of the Doce River.
The Landsat 8 image from September 11, 2015, shows what the mouth of the Doce River looks like under normal conditions. A Landsat 8 image acquired on November 30 shows a plume of sediment flowing into the Atlantic Ocean. This may be contaminated sediment from the dam breach. Advanced Landsat 8 capabilities, including the new coastal aerosol band and superior instrument performance, may improve monitoring the extent of sediment flow in the river.
Near-surface permafrost in Alaska is in danger of degrading with projected warmer conditions. Detailed information is needed to adequately monitor permafrost, but previous modeling of permafrost properties has typically been done at coarse resolution. A new study, led by the USGS Earth Resources Observation and Science (EROS) Center, developed the first medium-resolution (30-m) map of near-surface (within 1 m) permafrost for all of mainland Alaska.
Researchers used models to project permafrost degradation in the future based on various climate scenarios described in the Intergovernmental Panel on Climate Change (IPCC). Projections indicate that climate impacts (excluding fire impacts) will cause a decrease in near-surface permafrost of 16 to 24 percent by the end of the 21st century. Predictions of permafrost degradation were most pronounced for central Alaska, where permafrost temperatures typically hover around the melting point of 0°C.
The colors on this map indicate the probability that there is near-surface permafrost currently. Red and orange shades are areas with a low probability of permafrost, and blue shades are areas with a high probability of permafrost. When comparing the current map to future scenarios, the expectation of degraded permafrost is evident.
The mapping of permafrost distribution across Alaska is important for land-use planning, environmental assessments, and predicting future vegetation and carbon stocks. For more information, see the research article in Remote Sensing of Environment.
Two dams at an iron ore mine in southeastern Brazil broke on November 5, 2015, sending mine waste cascading into nearby valleys. The muddy floodwaters destroyed hundreds of homes in the village of Bento Rodrigues, which lies in a valley below the mining area. Natural color images from Landsat 8 compare how the area looked before the breach in the dams to how it looked one week after the incident.
The orange colors along the left side of the images are open pit iron ore mines. The dams burst from the tail