The erosion base is the height up to which the erosion of a flowing water is effective. No river can erode deeper than the altitude of its mouth . This is usually the sea level . Above the erosion base, the river tries to create an ideal gradient curve, a compensation curve in the longitudinal profile between the source and the mouth, through retreating erosion .
The absolute erosion basis for a river network is usually the sea level. For tributaries, the height of the confluence with the receiving water forms a regional erosion basis. In addition, local bases of erosion can also occur, such as swells in the river bed or a lake through which the river flows , i.e. places at which an erosion path changes into an embankment stretch. The compensation of the slope curve is then adjusted in sections to the altitude of the local erosion base. For the endorheic rivers in arid regions, the drainless basins represent the erosion base. The erosion base of the Jordan , the Dead Sea , is around 420 m below sea level.
If the erosion basis changes, the equilibrium state - whether reached by the river or not - is disturbed and the erosion and accumulation behavior is adjusted . If the base is lowered, for example by a drop in sea level or by removing a previous threshold, the river turns to increased deep erosion and cuts into the previously deposited sediments . If, on the other hand, the erosion base increases due to a rise in sea level or the creation of a new barrier, the river accumulates until it has reached its level again. Changes in the erosion base are often related to tectonic activity.