Improved unit hydrograph identification for seven Welsh rivers: implications for estimating continuous streamflow at ungauged sites
ABSTRACT A unit hydrograph-based continuous rainfall—streamflow model is applied at daily time step to several catchments in Wales. Two calibration methods are compared for seven catchments. Five of the catchments are among 60 basins in England and Wales for which models were derived by other investigators using the first calibration method, in order to devise a regionalization scheme allowing model parameters to be estimated from catchment properties. The paper shows that in several cases the first calibration method tends to overestimate low flows and give a positively biased estimate for one of the unit hydrograph parameters. It also shows that the second parameter calibration method can often overcome this problem, yielding model parameters more suitable for regionalization with respect to physical catchment properties. Implications of the work are discussed in the context of improving regionalization schemes where the estimation of streamflow in ungauged basins is the major objective.
- SourceAvailable from: Walter Collischonn
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- "When the purpose of modelling is to characterise catchment-scale rainfallestreamflow behaviour, rather than simply achieve a best fit between observed and modelled flows, reliance on a single objective function can be inadequate or, worse, misleading (e.g. Boyle et al., 2000; Littlewood, 2003). Using a range of model-fit diagnostic statistics provided by ICP, either singly or as a combination of two or more, the modeller can interact with the package and select a model 'fit-for-purpose'. "
ABSTRACT: The performance of a simple, spatially-lumped, rainfall–streamflow model is compared with that of a more complex, spatially-distributed model. In terms of two model-fit statistics it is shown that for two catchments in Brazil (about 30,000 km2 and 34,000 km2) with different flow regimes, the simpler catchment models, which are unit hydrograph-based and require only rainfall, streamflow and air temperature data for calibration, perform about as well as more complex catchment models that require additional information from satellite images and digitized maps of elevation, land-use and soils. Simple catchment models are applied in forecasting mode, using daily rainfall forecasts from a regional weather forecasting model. The value of the rainfall forecasts, relative to the case where rainfall is known, is assessed for both catchments. The results are discussed in the context of on-going work to compare different modelling approaches for many other Brazilian catchments, and to apply improved forecasting algorithms based on the simple modelling approach to the same, and other, catchments.Environmental Modelling and Software 09/2007; 22(9):1229–1239. DOI:10.1016/j.envsoft.2006.07.004 · 4.54 Impact Factor
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- "has not been tried previously, but preliminary work has been carried out on catchments in the Murray-Darling Basin in Australia (Croke, 2002). Other recent work (Littlewood, 2003) has demonstrated how, for several catchments in Wales, IHACRES model-fits can be substantially improved at low flows by using FDCs as an additional step to a " standard " model calibration procedure. "
ABSTRACT: The IHACRES rainfall-streamflow modelling approach provides a powerful set of techniques for assisting with parametrically efficient regional- ization of streamflow response characteristics (unit hydrograph and loss module parameters) from inputs of rainfall, evaporation surrogates and physical catchment descriptor data. Recent work has indicated where further improvements can be made to the model structure and its model parameter estimation procedure, for regionalization work. IHACRES could, therefore, form a useful component of PUB, whence its continuing development would benefit greatly from application to PUB data sets and exposure to the wider PUB community. In order to register IHACRES at the Brasilia PUB kick-off meeting, and to seek comments as to how it might best contribute to the PUB Decade, this paper has the following objectives: (1) to outline the IHACRES approach and techniques, and their roles in assisting with regionalization; (2) to discuss the relevance of IHACRES within PUB; and (3) to propose an IHACRES component of PUB.
Hydrological Sciences Journal/Journal des Sciences Hydrologiques 12/2005; 50(6):1053-1068. · 1.25 Impact Factor
- "The UH approach is also used for the simulation of continuous streamflow (e.g. Littlewood, 2003). Even in the present era of high-speed computers, the UH approach is being employed in hydrological models (e.g. "