Unit hydrograph based forecast model

Abstract

The paper presents a procedure for the on-line estimation of the (j)-index and rainfall excess as a storm progresses in time. This enables the application of a unit hydrograph model in real-time river flow forecasting. The rainfall and runoff readings up till the time of forecast are used to obtain the current estimate of the cj)-index and rainfall excess. The rainfall excess thus computed is convolved with the unit hydrograph to formulate the forecast. The success of the suggested procedure is demonstrated on two Indian catchments. Modèle de prévisionbasé sur 1'hydrogramme unitaire RESUME Dans cet article on propose la forme discrète du modèle de 1'hydrogramme unitaire pour le calcul des prévisions sur deux bassins indiens. Le modèle exige la connaissance de la pluie excédentaire au fur et à mesure que les précipitations progressent dans le temps. Les lectures de précipitations et de débits jusqu'au moment de la prévision sont rapportées au taux de réduction moyen pour atteindre l'objectif ci dessus. On discute des résultats et on conclut que ce modèle simple donne de bons résultats sur les bassins étudiées.

Rainfall–runoff modelling of ephemeral streams in the Valencia region (eastern Spain)

“…O'Connell and Clark (1981) and Reed (1984) provide reviews of many of these. These include conventional methods such as the unit hydrograph (Chander and Shanker, 1984), S-curve, Clark method, linear cascade reservoir model, conceptual models and non-linear storage models (Bobinski and Mierkiewicz, 1986;Corradini et al, 1986;Corradini and Melone, 1987). The hydrograph simulation model used in this work consisted of a simple rainfall-runoff transfer function that has been developed at the University of Salford by Dr Tilford and his co-workers.…”

A SEMI‐DISTRIBUTED ADAPTIVE MODEL FOR REAL‐TIME FLOOD FORECASTING1

“…A different procedure for estimating the losses may be chosen, for example by using the matching of observed and computed runoff during a short period prior to each forecast (Simpson, et al, 1980;Chander and Shanker, 1984). This method should be more stable, and therefore less flexible, than that based only on the present observed runoff.…”

“…Many models of this type have been proposed and a few of them are being used for on-line forecasting purposes (Reed, 1984). These adaptive models include the unit hydrograph based linear models (Chander and Shanker, 1984), the transfer function-noise models (Moore, 1982), the nonlinear storage models (Lam. bert and Lowing, 1980) and the conceptual models (Kitanidis and Bras, 1980a;Manley, et al, 1980).…”

“…Therefore, simple models are generally preferred in operational applications to flood forecasting. For example, unit hydrograph (UH) based flood forecasting models have been usefully applied in real-time in basins whose area is less than -1000 2 (Simpson, et al, 1980;Chander and Shanker, 1984). However, though the UH method is frequently employed also for transforming effective rainfall to obtain direct runoff in larger basins, its on-line application to basins of a few thousand square kilometers is questionable.…”

“…Then corrections of the forecasts are carried out through the updating of the -index as a storm progresses in time. Model applications to isolated storm events occurred on two Italian basins are discussed and the results compared with those obtained, for the same events, by the on-line UH based model proposed by Chander and Shanker (1984 Corradini, Melone, and Ubertini A given basin is divided into zones by isochrones of travel time from the outlet. Rainfalls and losses are represented by preserving their variations from one zone to another, while they are assumed uniformly distributed within each zone.…”