The Long Profile of a River

What is a long profile?

The long profile shows how the angle of a river channel changes from its source to its mouth (for example, sea, lake). The long profile shows the tallness of the river bed, over the base level, along the entire length of the river. 

Base level – this is the absolute bottom that a river bed can be dissolved too. The base degree of the river usually is ocean level or the degree of the lake, and so on that, the river is streaming into. 

Over the whole course of the river, the measure of erosion and deposition are adjusted (complete erosion rises to add up to deposition). In any case, the paces of erosion and deposition differ along the course of the river, this can prompt the formation of landforms, for example, waterfalls and lakes (where erosion is more prominent than deposition), and results in a long lopsided profile. 

Since the pace of erosion, rises to the pace of deposition after some time, the long profile of the river changes from a lopsided bend to a smooth bend, which is known as an evaluated profile. 

The three phases of the river’s course 

The chart above shows the river isolated into three phases – upper (near the source), center, and lower (close to the mouth). The vitality of the river fluctuates inside each phase of the river. 

Upper stage – soak angle, the river is high above ocean level. It has much potential vitality, which can be changed over into different kinds of vitality, for example, ongoing vitality. 

Center stage – the angle of the river diminishes as you approach the center stages, potential vitality is changed over into dynamic vitality (development), and the rivers speed increments. 

Lower stage – here, the river has a great deal of ongoing vitality, it streams rapidly, yet it does not have much potential vitality. 

Channel attributes influence both speed and release 

As you move downstream from a river’s source to its mouth, speed (dynamic vitality) and release increment. Release increments because of tributaries (littler rivers/streams) joining the central channel and further contributions from surface overflow as you go downstream. The river’s speed is legitimately impacted by slope, the pace of release and the attributes of the river channel. 

Ongoing vitality – the most significant extent of a river’s motor vitality is spent defeating rubbing. Its remainder causes erosion and is utilized for transportation. The more prominent a river’s accessible vitality for erosion and transportation, the more effective it will be. Productive rivers have high speed, high release and low contact. 

The Hydraulic span estimates effectiveness. The higher the pressure-driven sweep, the more noteworthy a river’s productivity. 

Pressure driven span – channel cross-segment region isolated by the length of the wet border (length of the banks and river bed which are in contact with the water). 

Rubbing is made by contact between the water and the wetted edge; this expands vitality misfortune and results in the river easing back down. 

The bigger the pressure-driven range, the littler the extent of water in contact with the wetted border. This outcomes in less grinding lessen vitality misfortune and build speed and release 

River channels that are smooth, thin and profound have more significant water-driven span’ and are more proficient than shallow, more extensive river channels. 

Channel harshness – projecting banks and enormous, precise rocks on the river bed increment the wetted edge and increment contact, decreasing effectiveness, speed and release. 

Choppiness increments as channel harshness build. This prompt expanded erosion because the violent stream is more proficient at getting particles than no fierce stream. 

The upper phase of the river is the place channel unpleasantness is grinding away is most prominent. This implies the upper phases of a river loses a great deal of it is a vitality to erosion, implying that even though the inclination of the river is steepest right now, and speed are at their most minimal under ordinary conditions. 

Interestingly the lower phases of a river channel have smoother bed and banks, bringing about less grating and less vitality misfortune, and, because of this release and speed are most noteworthy in the lower phases of a river. 

The cross profile 

The outline above incorporates cross profiles of a run of the mill river. The cross profile shows what a cross-area of a river channel or river valley resembles. The river valley’s cross profile changes all through the various phases of a river’s long profile. 

Upper stages – vertical erosion makes slender valley floors and soak angular valleys 

Center stages – parallel erosion makes more extensive valleys. Flood fields are formed on the valley floor through a deposition. 

Lower stages – wide valley with delicate inclining sides and broad flood fields brought about by proceeded with deposition. 

River landforms 

Picture of Aria Force, Cumbria. Shows the canyon, which has been removed by the erosive powers of the water and the dive pool it’s made in the frontal area.

Fluvial erosion makes Waterfalls, Rapids, and Potholes. 

Waterfalls 

Waterfalls form where hard stone and softer stone meet. The softer stone is dissolved quicker by the river than the hard stone, which causes a stage in the river bed. 

Because of an absence of contact water streaming over the progression speeds up, this prompts more prominent erosive force, which thus brings about further erosion of the soft stone, and, undermining of the hard stone. 

Kept undermining of the hard stone can prompt a breakdown, particles of the crumbled rock are twirled around by the rough water, and a dive pool is cut out at the foot of the waterfall by scraped area. 

Kept undermining after some time, prompts further breakdown, the waterfall withdraws (moves back up the channel) and deserts a high sided gorge. 

Picture of crumbled rock particles at the Aira Force in Cumbria. 

Soak sided channel slice through the soft stone. Tempestuous water can be found out of sight of the pictures taken at the Aira Force in Cumbria. 

Potholes 

Potholes are little round openings in the river bed, which are formed by scraped spot. The river’s bedload is whirled around by disturbance; the roundabout movement rubs and scratches openings out of the river bed, forming potholes. 

Rapids 

Rapids are segments of a river that have a generally steep inclination. Because of the slope of the river, hard water streams rapidly more than a few areas of hard stone, making the rapids. Rapids are, in sure regards, similar to smaller than expected waterfalls. 

Meanders

The picture shows disintegrated material stored within a twist on the River Roe at Roe Valley Country Park, Limavady, Northern Ireland 

Large clearing bends in the center, and lower phases of a river are called wanders. A mix of erosion and deposition forms wanders. 

Where rotating territories of deep water (pools) and regions of shallow water (riffles) form, similarly divided, along a stretch of the river bed, wanders will create. The separation between the pools is somewhere in the range of five and multiple times the width of the river. 

The river direct is more profound in the pools, which implies it is increasingly active, has more vitality, and erosive force. Conversely, because of grinding, the river loses vitality as it streams over the riffles. 

The dispersing of the riffles and pools and the separation between them prompts the progression of the river, turning out to be lopsided and greatest stream at that point gets focused on one side of the river. 

As the water accelerates, choppiness increments inside and around the pools. The water at that point begins to contort and curl, helicoidal stream (corkscrew-like current) creates, these currents move along the river between the pools, spiraling between the banks. 

The helicoidal stream builds erosion, extends the pools further, and brings about dissolved material being stored within the next twist (see the picture of the River Roe above), where the river loses a portion of its vitality. The proceeded with procedures of erosion and deposition bring about the formation of the wanders’ particular awry shape.  

Picture indicating how wanders form. 

Picture demonstrating the formation of an oxbow lake.

Oxbow lakes form from wanders that have been ruptured during occasions, for example, floods. The neck of the circle of the wander is gotten through by the rising water; disintegrated material is then stored where the neck has been gotten through. The wander is then cut off from the remainder of the river, abandoning an oxbow lake. 

Fluvial deposition causes Braiding, Flood Plains, Levees and Deltas 

Twisting – a plaited river is a river that has isolated into some little, winding channels that, in the end, re-join to form a single channel once more. 

Twisting happens when a river is conveying a gigantic measure of dissolved dregs, and it is speed either drops or, the river’s load is incredible to the point that residue is saved in the channel. This leads to river partitioning into various channels, which inevitably re-join and form a single channel further upstream. 

Flood Plains – the regions of level land either side of a river. 

At the point when a river floods it is banks onto the flood plain, there is an expansion in wetted edge and a decrease in water-driven range. This causes an expansion in contact, and a decrease in speed, which prompts deposition of fine sediment and sand over the flood plain. 

Picture of a meandering river. The picture shows the floodplain and levee along the banks of the River Annan, Scotland. 

Levees – naturally raised dikes that form as rivers flood their banks. 

During a disintegrated flood, the material is kept over the flood plain; the most substantial material is a store

Deltas form at the mouth of the river where it joins the sea or a lake. 

As a river arrives at sea (or another water body) its vitality is consumed by the more slowly moving water of the sea. This prompts the deposition of silt that the river is conveying. The kept residue (alluvium) develops until it is level transcends ocean level, which incompletely obstructs the mouth of the river. The river at that point needs to twist into various distributaries forming a delta that empowers the river to arrive at the sea. 

Restoration implies a river can continue vertical erosion 

Restoration of the river is the point at which the base of a river is brought down, either by the crustal inspire (ground level rising) or by a drop in ocean level. Revival builds the river’s potential vitality, and it is vertical erosion potential. The river’s long profile is stretched out by revival, and a knickpoint (sharp change in angle, for example, waterfall) will form checking where the new and unique long profiles meet. 

Landforms related to the revival 

River patios – former flood fields that sit above cutting-edge flood levels because of expanded vertical erosion. 

Etched wanders – profound, soak sided, winding valley, which forms when vertical erosion increments and wandering rivers keep to their course. One staggering case of an etched wander is the Grand Canyon in Arizona, USA, where you can see the Colorado River streaming far beneath the first flood plain.

References

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Cite/Link to This Article

  • "The Long Profile of a River". Geography Revision. Accessed on March 3, 2021. https://geography-revision.co.uk/a-level/physical/the-long-profile-of-a-river/.

  • "The Long Profile of a River". Geography Revision, https://geography-revision.co.uk/a-level/physical/the-long-profile-of-a-river/. Accessed 3 March, 2021.

  • The Long Profile of a River. Geography Revision. Retrieved from https://geography-revision.co.uk/a-level/physical/the-long-profile-of-a-river/.