Chapter 1: Introduction
Hydrology, as defined by the 2001 Texas Department of Transportation (TxDOT) Hydraulic Design Manual, “deals with estimating flood magnitudes as the result of precipitation.” Estimating the magnitude of an extreme flood event is essential in the design of highway drainage facilities such as culverts, bridges,
storm drain systems, and detention determination of the quantity of water
facilities. The time-dependent to be conveyed by each structure
and the road. extreme flood
With proper design of event are minimized.
The principal factors affecting flood magnitudes in a watershed include runoff (influenced by precipitation and abstractions), watershed area information
(slope, longest flow path, systems, flow diversions, development also influence
area), land use, and soil type.
channelization, and the magnitude of an
impervious cover from urban extreme flood event. Currently,
estimate hydrologic parameters such and abstrations. These parameters are
as flow path length, watershed area, slope, necessary in determining the peak discharge
at an area outlet, although the contributing watershed
many runoff estimation and the watershed slope
techniques assume the size as the principal variables.