Beat Bama Blood Drive. Showcasing Louisiana. Player of the Week. Submit Nomination for Player of the Week. Latest Newscasts. Investigate TV. Election Results.
Gray DC Bureau. Louisiana Weekend. Great Health Divide. Explaining Different River Stages. Bankfull stages on streams with natural or manmade high banks can be defined by the predominant vegetation line on the banks. The bankfull stage on many streams is associated with the 2-year recurrence interval flood.
Bankfull stage is not necessarily the same as flood stage. The type of action taken varies for each gage location. Gage data should be closely monitored by any affected people if the stage is above action stage. Flood Stage - an established gage height for a given location above which a rise in water surface level begins to create a hazard to lives, property, or commerce. The issuance of flood advisories or warnings is linked to flood stage.
Not necessarily the same as bankfull stage. Flood categories are terms defined for each gage location that describe or categorize the observed or expected severity of flood impacts in the corresponding stream segment or nearby stream. Therefore, the stage for a given flood category is usually associated with lowest water level corresponding to the most significant flood impacts somewhere in the reach.
The flood categories used in the NWS are minor, moderate, and major flooding, but all three of the flood categories do not necessarily exist for each gage location.
It means that the gauge is reading at or below the agreed-upon zero level. That gauge zero level is chosen considering many factors, like the USGS references or benchmarks that are near to the gauge site, or an historical level that may have been used for a hundred years or more.
These gauge zero levels are not changed very often. Silt may deposit in the river channel over time filling the channel up , or the channel bottom may be scoured out to a deeper level by strong currents.
For example, most of the gauges in the Susquehanna Basin experienced their record Flooding during Agnes in If the gauge zero level was changed on a whim, all the historical data for the gauge site could be rendered useless or at least very confusing. They know that the water reaches the front steps of their house at 17 feet using the current values. If the level was to change up or down just to avoid having a negative value, it might become confusing for them to remember the new level which would impact their home.
There is a collaboration between many government agencies in order to settle on a gauge zero, and which Datum way of mapping the earth will be used as a basis. Not many sites in the region actually go below zero Renovo and Williamsport are two examples that do.
When they do go below zero, it is usually a sign of a prolonged dry spell. The river channel is deep and wide and the land around the river is flat. Energy in the river is at its lowest and deposition occurs. Rivers are split up into three parts : the upper course, the middle course, and the lower course. The upper course is closest to the source of a river. The land is usually high and mountainous, and the river has a steep gradient with fast-flowing water.
There is a lot of vertical erosion and weathering. Youthful Stage - Rivers. At the youthful stage the river is flowing fast down steep gradient, therefore there is much more evidence of erosion at this stage. A very common feature of erosion is interlocking spurs picture which are formed when the river meets a block of hard rock it cannot flow through or erode down.
A mature river is fed by many tributaries and has more discharge than a youthful river. Its channels erode wider rather than deeper. Most rivers begin life as a tiny stream running down a mountain slope. They are fed by melting snow and ice, or by rainwater running off the land. The water follows cracks and folds in the land as it flows downhill. Small streams meet and join together, growing larger and larger until the flow can be called a river. You can make a good approximation of the absolute age of a " river " by determining the absolute age of the deepest river deposits in the specific basin.
In the case you have two rivers and you want to determine the relative age, you can also use the ages of the deposits. River level is the depth of water at a monitoring station, measured in metres to a specified datum.
Flow is the volume of water passing a monitoring site, measured in cubic metres per second.
0コメント