The Evolution of a Gravel Bar

Abstract

One of the characteristic features of many Ozark streams is the occurrence of gravel deposits usually found on the concave bank of river-bends. It has been suggested (Anderson, 1949) that these deposits, known as 'gravel bars, may evolve their own flood-control systems. An investigation of one such bar on the Meramec River, at Gray Summit, Missouri, was made in order to determine how the bar had evolved physically, and, in a general sense, how this change affected and was affected by the natural populations of the river bank. It is generally known that the size and shape of many gravel bars is not constant, but there has been no quantitative work to show this. The determination of the physical changes of this one gravel bar necessitated the assembly of all available historical data, their reduction to a common scale, and the consequent plotting of all recorded changes. This assembly of historical data is not as difficult as it might seem. There usually exist, in offices of county engineers, fairly complete surveyor's reports which may go back 100 years or more, as at the Franklin County courthouse in Union, Missouri. In addition, the field offices of the U. S. Department of Agriculture frequently have large aerial photographs of the areas within their district. Data from these two sources, as well as some private aerial photographs, were used to chart the physical evolution of the gravel bar selected. The data follow: