Real-time streamflow data available on USGS pages are PROVISIONAL data that have not been reviewed or edited. These data may be subject to significant change and are not citable until reviewed and approved by the U.S. Geological Survey. Real-time...
The term "100-year flood" is used to describe the recurrence interval of floods. The 100-year recurrence interval means that a flood of that magnitude has a one percent chance of occurring in any given year. In other words, the chances that a river will...
A relationship is developed by USGS hydrographers between stage (usually expressed as feet) and discharge (usually expressed as cubic feet per second). This relationship, often called a rating curve, is developed by making frequent direct discharge...
At some USGS stream-gage installations, NWS maintains a separate stage sensor that is serviced by NWS technicians. Occasionally, calibration of any sensing device may drift from a 'true' value, so there may be differences between USGS and NWS data...
Stream stage is an important concept when analyzing how much water is moving in a stream at any given moment. Stage is the water level above some arbitrary point in the river and is commonly measured in feet. For example, on a normal day when no rain has...
Not directly. You cannot say that because a stream rises (doubles) from a 10-foot stage to a 20-foot stage that the amount of water flowing also doubles. Think of a cereal bowl with a rounded bottom. Pour one inch of milk in it. It doesn't take much milk...
Each reach is a continuous piece of surface water with similar hydrologic characteristics, such as a stretch of stream between two confluences or a lake. Some unconnected (isolated) features are also reaches, for example, isolated lakes and single,...
Continuous real-time water quality information is at Water Quality Watch Real-Time Water Temperature. These data are limited to measurable characteristics such as temperature, turbidity, specific conductance (salinity), dissolved oxygen, and pH (acidity...
The National Hydrography Dataset (NHD) is the culmination of cooperative efforts of the U.S. Environmental Protection Agency (EPA) and U.S. Geological Survey (USGS). It combines the best of the EPA Reach File Version 3.0 (RF3) and USGS Digital Line Graph...
The idea is to combine spatial accuracy with detailed features, attributes, and values. Information such as flow paths, permanent reach IDs, and hydrologic ordering can now be used in modeling. The NHD is not designed to replace or supercede existing...