Prediction in Ungauged Basin Based on Hydrological Similarity Analysis

Extrapolation of response information from gauged to ungauged basins is a appropriate and widely used method for Prediction in Ungauged Basin (PUB). Hydrological similarity between gauged and ungauged basins, derived from their similarity in how they respond to precipitation input, is the basis for classification, for transferability and regionalization. Usual measure of similarity is the correlation coefficient calculated pair wise from discharge time series. Unfortunately this measure mixes meteorological and hydrological effects. If the same catchment would have a different weather then the correlation becomes low and the catchments are considered as dissimilar. Two catchments are similar if in the common domain of meteorological forcing the resulting discharge is similar. Similarity can be defined as apparent similarity as well as behavioral similarity. Apparent similarity is defined on the basis of observable catchment properties, while behavioral similarity can be judged through the utilization of hydrological models. The fact that the hydrological similarity requires some kind of a model is not necessarily a good thing; this is why hydrological models usually agree with each other concerning the similarity of catchments. Under changing hydrological regimes, many standard procedures in hydrology are no longer valid and new analytical procedures need to be developed (or existing ones modified). This study is concentrating on developing new way for prediction in ungauged basins by analyzing the hydrological similarity between catchments. Empirical Copula density based dissimilarity measure is one of the approaches to predict ungauged basins in my research. Improve process understanding through research, as it is about prediction, where the increased focus on process is seen as the pathway to better model estimates for the future.