Geology News - Earth Science Current Events

Streamflow levels by state (compared to their historic record) for water-year 2006. Image by USGS

The US Geological Survey operates over 7000 stream gaging stations across the United States. These stations monitor stream stage, discharge and other parameters and report that data instantly to USGS. Many of these stations are published to the web. Near-real time and historic streamflow data can be accessed at the USGS Water website.

For the first time, USGS has prepared an annual summary of this data and this year's summary is now on the web. This summary includes a variety of maps, charts and tables that show regional, seasonal and historic patterns of stream flow.

The summary report can be accessed at The USGS WaterWatch Website.

Related Articles on Geology.com: What is a Hydrograph? What is a Gaging Station?

Labels: Floods-Flooding

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Flooding in the African Sahel has been a significant problem over the past few weeks. The African Sahel has a semi-arid climate, however, it can receive significant precipitation during the mid-June to mid-September rainy season. Very heavy rains during the last weeks of July and early August have produced floods which have caused death, displacement and destruction.


Image by NASA Earth Observatory
The images above show how the flooding Omo River has covered much of its delta on the north shore of Lake Turkana. This flooding has expanded Lake Turkana northward, flooding significant areas in Ethiopia and Kenya. The dark blue color of the lake in the bottom photo is typical; however, heavy loads of suspended sediment in the water give Lake Turkana a turquoise color in the top photo.


Image by NASA Earth Observatory

The images above show how the Goroui River, Niger River and their tributaries are flooding their valleys in Niger and Burkina Faso. The land over much of this area is barren and with hard soils that do not easily absorb water. This situation can yield a large amount of runoff with only minor rainfalls.

View more satellite images of flooding in the Africa Sahel at the Earth Observatory website.

Labels: Floods-Flooding

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New Orleans is not the only place in the United States where levees protect land that is below sea level. A feature article at the Geotimes website details the importance and vulnerability of levees in the Sacramento River Delta area. From the article by Megan Sever...

"Central California’s levees protect Sacramento, Stockton and other cities, as well as much of the nation’s agriculture and the water supply of 23 million Californians, including most of Southern California. In the event of a major breach, these areas could be up to 5 meters underwater, and the water supply to Southern California could be knocked out for a period of years."

Sacramento River Delta Landsat Image / NASA
Although these levees are not subject to hurricane flooding and related storm surge events they are subject to seasonal flooding of their river systems along with a significant earthquake risk.

The Geotimes article provides details about the levees in the Sacramento River Delta area and others in central California which were built in the 1800's from gold dredgings, and levees in the Netherlands. Read the Geotimes article: When Levees Fail.

Labels: Floods-Flooding

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The stream monitoring done by a USGS stream gage typically costs between $12,000 and $15,000 per year. USGS operates about seven thousand of these gages across the United States. That's a lot of money! Over 100 of these gages were closed during the past year because of low levels of funding and other gages are scheduled to close during 2006.

USGS provides much of the funding for this gaging network. Other federal, state and local government agencies help support the costs of those gages which provide information critical to their projects. Companies and organizations also contribute towards the maintenance of specific gages.


Gaging Station Image by USGS

Hydrograph by USGS

Information for many of these gages is published to the web and can be viewed at the USGS Stream Monitoring Website. This information is valuable for many flood control, water supply, wildlife management and recreational purposes. If you work for or are a member of an organization that values the gaging station data perhaps you can find a way to contributed towards its generation?

See more information at the Geology.com pages for Hydrographs and Gaging Stations.

Labels: Floods-Flooding

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FEMA has improved their ability to serve digital copies of the flood insurance rate maps via the web. Many of these maps can now be viewed online in the same familiar format as the paper maps.
Image by FEMAView Digital Flood Insurance Rate Maps at the FEMA website.

Labels: Floods-Flooding, Maps

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NOVA Science Programming has published a website to support their documentary on the Ice Age flooding event in which a vast lake, known as Glacial Lake Missoula, burst through an ice dam and flooded broad areas of the Pacific Northwest. Vic Baker, expert on this topic describes what it would have been like to witness the flood and how knowledge about this flood can be applied to other situations on Earth and even to understanding the landscape of Mars.

Screenshot of the NOVA Megaflood WebsiteLearn more at NOVA's Lake Missoula Flood website.

Labels: Floods-Flooding

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At present it is unclear how homes damaged by Hurricane Katrina and related flooding will be covered by various types of insurance. Hurricane insurance policies might not cover flooding - and flood insurance policies might not cover flooding associated with a hurricane or with a levee break.
Read more about Hurricane Katrina Insurance Problems at The Independent Online Edition website.

Labels: Floods-Flooding, Hurricanes

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Earth Observatory has posted satellite images of Gulf Coast flooding caused by Hurricane Katrina. These images clearly show enlargement of Lake Pontchatrain and Lake Maurepas plus water filling the streets of New Orleans.

Image by EarthObservatorySee high resolution images and read more at the Hurricane Katrina / New Orleans Flooding pages at Earth Observatory.

Labels: Floods-Flooding, Hurricane-Katrina

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The Federal Emergency Management Agency has been upgrading the FIRMs (Flood Insurance Rate Maps) on their interactive website. Now you can go there, type in your address and for most parts of the USA get a rough idea of the flood hazard. Also on the FEMA website are tutorials on how to read a flood map and other useful information. View flood insurance rate maps and learn more about them at FEMA's Flood Mapping website. While you are there you can use the same interface to view hurricane track maps, tornado incidence maps, and earthquake epicenter maps.

Labels: Floods-Flooding, Maps

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Heavy summer rains in eastern and southern China have resulted in widespread flooding and deadly mudslides. The image below shows cumulative rainfall for June 13 through June 28, 2005. Some areas of China have received up to 400 mm (16 inches) of rain during this two week period. Visit the Earth Observatory website to learn more about this image and see other information about flooding in China.

Labels: Floods-Flooding

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Record flooding levels have resulted in over 500 deaths and 2,000,000 evacuations in southern China. The Pearl River is at record levels and significant damage has occurred in the Guangdong Province. Visit the Los Angles Times website to learn more about Record Flood Levels in China.

Labels: Floods-Flooding

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