Parameters in Estimation of the Design of Floods and Catchment Response - Term Paper Example

Floods are extreme events in the hydrologic cycle. Therefore, its magnitude is inversely proportional to its occurrence frequency. For the design of any hydraulic structure such as dams, it is important to determine the estimate of the design flood events. This is because the flood events represent the maximum discharge of a given area during a specified period. The hydraulic structures need to meet their intended purpose; this can be enhanced by determining the estimated design flood accordingly.

Before surface runoff is experienced in any catchment, the rate of infiltration must be less than the rate of precipitation, in that regard, the response and the characteristic of the catchment play a major role in determining the runoff. If the catchment has soils of low infiltration rates then that means that the runoff to be experienced in such a region is more and occurs after a very short time as compared to a catchment characterized by soils of high infiltration rates. In addition, the vegetation influences the rate of water infiltration in that, a catchment with more vegetation, the infiltration rate is higher than a place with low vegetation growth.

It is also important to note that, the distribution and the duration of the rainfall on the catchment will also influence the runoff in that if the distribution is even throughout the catchment and takes a considerably longer time then the runoff experienced would be very high and vice versa (Royappen, M., et al. 2002). Considering the duration of the rainfall in determining the surface runoff, a hyetograph or a hydrograph is used. The time that a catchment takes to respond to rainfall is related to a number of factors such as; the catchment characteristics including the land cover, soils and obstruction, the river channel, and other subsidiary channels’ geomorphology, catchment geomorphology, and climate of the catchment(Ramser 1927).