How to Select a Reference Basin in the Ungauged Regions

AbstractLong-term hydrologic prediction in ungauged basins is one of critical issues in the field of hydrologic calculations. Hydrologic analogy is an important method for long-term hydrologic prediction and hydrologic calculation in ungauged basins. The key point of hydrologic analogy is how to select a reference basin. This paper systematically discusses four popular methods to select a reference basin in China, which include grey analysis, fuzzy analysis, projection pursuit (PP), and set pair analysis. Through a case study in a small basin in Hebei Province, North China, the four methods are applied to select a reference basin. The advantages and disadvantages of these methods are explored. The results indicate that all four methods could be used in selecting a reference basin. It will depend on the familiarity and the experiences of the users with a specific method.