What processes cause rivers to erode incised valleys and canyons? ...

[ishan]

What processes cause rivers to erode incised valleys and canyons?
 
  What will be an ideal response?

Question 2

What would you suspect to happen to the load of a stream if its channel shape changes from being narrow and deep to being wide and shallow (assume the area of the channel and average velocity remain constant)?
 
  What will be an ideal response?

[Eunice618]

Answer to Question 1

Climate change can impact base level. A decrease in sediment load or an increase in stream power can cause base level to fall and erosion to occur. Tectonic uplift also leads to incision, assuming base level does not change. Both are significant processes and closely linked in stream development.

Answer to Question 2

If the area of the channel and average velocity remain constant, then the discharge remains constant as well. The only thing changing is the water depth. The shallow water depth will result in a lower shear stress which means a lower stream power. The stream's load (bedload and/or suspended load) will most likely be deposited as alluvium.

[ishan]

TYSM

[scikid]

Excellent