The SCS National Engineering Handbook is intended primarily for Soil Conservation Service (SCS) engineers and technicians. It presents material needed to carry out SCS responsibilities in soil and water conservation and flood prevention. Section 4, HYDROLOGY, contains methods and examples for studying the hydrology of watersheds, for solving special hydrologic problems that arise in planning watershed-protection and flood-prevention projects, for preparing working tools needed to plan or design structures for water use, control, and disposal, and for training personnel newly assigned to activities that include hydrologic studies.