ABSTRACT
Aggradation, like water erosion, occurs in two basic forms: sheet deposition, or slope wash, at the slope base and channel deposition. The geomorphologist and hydraulic engineer see erosion and aggradation processes from somewhat different points of view, each appropriate to the aims of his field of study. The essential point is that accelerated erosion in which a gully svstem is developed on previously-smooth, unchanneled slopes is an adjustment of the drainage system toward a higher drainage density and a system of steeper slopes. Excessive decrease of slope of the stream bed or ground surface in the downstream direction is a second cause of velocity reduction. Another aspect of aggradation dynamics deals with textural differences between parent-material and aggraded products. In general, the slope-wash and valley alluvium produced in the aggradational cycle will be the coarser fraction of the parent-material from which the fine clays and silts, readily carried in suspension to distant down-stream points, have been sorted.
