Design Flood Estimation Using Scaling Approach

Estimation of design flood and its characteristics is one of the challenges in the field of hydrology. Traditional practice is to estimate design flood by fitting a statistical distribution to peak flow data available at target location(s). In situations where data are limited or unavailable at target location, hydrologists employ regionalization approaches. There is a dearth of meaningful efforts to investigate their effectiveness in different parts of the world. In one of those referred to as the scaling approach, peak flows at sites in a region are assumed to scale with the corresponding catchment areas. This paper presents results from investigations carried out to examine effectiveness of the scaling approach in predicting flood quantiles at target sites in Godavari and Mahanadi river basins of India and 18 United States Geological Survey (USGS) water resources regions. Results show that scaling approach is effective in six of the 18 USGS regions and the two Indian river basins. Equations relating first four moments to catchment area of a site are derived for each of the regions/river basins for which scaling is applicable, and their effectiveness in predicting flood quantiles at ungauged sites is investigated by performing leave-one-out cross-validation.