The Physical Factors that Govern the Formation of Temporary Waters

Abstract

Figure 2.1 shows the basic components of the runoff cycle which are important in the formation of both permanent and temporary ponds and streams. Precipitation is the most important source of water so far as the cycle is concerned. Before this water even touches the ground surface it can be intercepted several times by trees and other vegetation; water trapped on these exposed surfaces is very quickly evaporated by wind. The water that reaches the soil surface is taken up by infiltration and the rate at which this occurs depends on the type of soil and its aggregation. At this stage, in some exceptional clayey soils, water may collect on the surface in small depressions and form puddles and even small trickles. Both tend to be short-lived, as the water they contain is usually absorbed quite quickly by soil cracks and patches of more permeable soil over which it may run. Such water bodies are referred to as ephemeral streams and are apparent only after periods of high storm intensity or snow melts; they seldom contain any animal or plant life.