Hydrologic Characteristics of Soil Types

Watershed engineering encompasses not only the development of each acre to its maximum benefit, but also the integration of these developments into a system of hydrologic performance for the entire watershed. Although the three disciplines—irrigation, drainage, and watershed engineering—are fully cognizant of their common factors, there has not been a good inter-use of basic concepts and basic information. There is one significant common denominator—soils. The Soil Conservation Service has grouped more than 3,000 soils of the United States according to their rate of water intake after prolonged wetting. Published soil survey reports provide a basis for estimating the volume of storage to be exhausted during the saturation process. Partitions of this storage, as freely-drained porosity and porosity drainable by plant use, are of interest to drainage engineers, and irrigators, respectively. Both are useable in estimating infiltration as an exhaustion phenomena convergent upon the low near constant rate after prolonged wetting.