Abstract
Abstract. Regionalisation provides a way of transferring hydrological information from gauged to ungauged catchments. The past few decades has seen several kinds of regionalisation approaches for catchment classification and runoff predictions. The underlying assumption is that catchments having similar catchment properties are hydrological similar. This requires the appropriate selection of catchment properties, particularly the inclusion of observed hydrological information, to explain the similarity of hydrological behaviour. We selected observable catchments properties and flow duration curves to reflect the hydrological behaviour, and to regionalize rainfall-runoff response for runoff prediction. As a case study, we investigated 15 catchments located in the Yangtze and Yellow River under multiple hydro-climatic conditions. A clustering scheme was developed to separate the catchments into 4 homogeneous regions by employing catchment properties including hydro-climatic attributes, topographic attributes and land cover etc. We utilized daily flow duration curves as the indicator of hydrological response and interpreted hydrological similarity by root mean square errors. The combined analysis of similarity in catchment properties and hydrological response suggested that catchments in the same homogenous region were hydrological similar. A further validation was conducted by establishing a rainfall-runoff coaxial correlation diagram for each catchment. A common coaxial correlation diagram was generated for each homogenous region. The performances of most coaxial correlation diagrams met the national standard. The coaxial correlation diagram can be transferred within the homogeneous region for runoff prediction in ungauged catchments at an hourly time scale.
Highlights
Flash floods are one of the most destructive hazards in the world, in China
The question is how to build an appropriate rainfall runoff relationship for accurate and timely runoff prediction at the ungauged catchments? Many hydrologists focus on the concept and method of regionalisation transferring of hydrological information/response from gauged to ungauged environments
We further evaluated the transferability of coaxial correlation diagrams within the homogenous region
Summary
Flash floods are one of the most destructive hazards in the world, in China. According to the statistics of the National Development and Reform Commission, China has 670 large rivers with the catchment areas over 3000 km, more than 8600 small and medium rivers with the catchment areas ranging between 200 and 3000 km, and much more mountainous gullies with the areas under 200 km. There has been no or few available streamflow data (ungauged) to derive reasonable rainfall runoff relationships for the small and medium rivers, despite the national initiative for hydrological monitoring system for small and medium rivers in China from 2011. The question is how to build an appropriate rainfall runoff relationship for accurate and timely runoff prediction at the ungauged catchments? Numerous regionalisation approaches have been proposed for runoff predictions from a catchment scale to global scale and from a short-term flood event to long-term series (Li and Zhang, 2017). The most popular regionalisation approaches are generally based on (1) spatial proximity, (2) regression, (3) physical and climatic similarity, (4) hydrological signatures/indices, (5) integrated similarity such as the combination of spatial proximity and physical similarity
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