Surface water hydrology: On‐line estimation

In recent years a large number of mathematical models of different types have been developed to represent various aspects of the rainfall‐runoff (R‐R) process. This proliferation of models has led some investigators to voice concerns about the difficulties that the practicing engineer faces in the selection of an appropriate model for his/her specific application. Given the amount of effort (in terms of money and time) that has been devoted to the development and improvement of R‐R models, it is perhaps disconcerting that the most widely applied technique for short‐interval (24 hours or less) on‐line flow forecasting is still the unit hydrograph. Clearly there seems to be some reluctance on the part of practicing hydrologiste to employ the newer models.