Articles | Volume 21, issue 11
Hydrol. Earth Syst. Sci., 21, 5647–5661, 2017
Hydrol. Earth Syst. Sci., 21, 5647–5661, 2017

Research article 15 Nov 2017

Research article | 15 Nov 2017

A comparative assessment of rainfall–runoff modelling against regional flow duration curves for ungauged catchments

Daeha Kim1, Il Won Jung2, and Jong Ahn Chun1 Daeha Kim et al.
  • 1APEC Climate Center, Busan, 48058, South Korea
  • 2Korea Infrastructure Safety & Technology Corporation, Jinju, Gyeongsangnam-do, 52852, South Korea

Abstract. Rainfall–runoff modelling has long been a special subject in hydrological sciences, but identifying behavioural parameters in ungauged catchments is still challenging. In this study, we comparatively evaluated the performance of the local calibration of a rainfall–runoff model against regional flow duration curves (FDCs), which is a seemingly alternative method of classical parameter regionalisation for ungauged catchments. We used a parsimonious rainfall–runoff model over 45 South Korean catchments under semi-humid climate. The calibration against regional FDCs was compared with the simple proximity-based parameter regionalisation. Results show that transferring behavioural parameters from gauged to ungauged catchments significantly outperformed the local calibration against regional FDCs due to the absence of flow timing information in the regional FDCs. The behavioural parameters gained from observed hydrographs were likely to contain intangible flow timing information affecting predictability in ungauged catchments. Additional constraining with the rising limb density appreciably improved the FDC calibrations, implying that flow signatures in temporal dimensions would supplement the FDCs. As an alternative approach in data-rich regions, we suggest calibrating a rainfall–runoff model against regionalised hydrographs to preserve flow timing information. We also suggest use of flow signatures that can supplement hydrographs for calibrating rainfall–runoff models in gauged and ungauged catchments.

Short summary
We evaluated predictive performance of a rainfall–runoff model whose behavioural parameters were gained against flow magnitudes only. The parameter sets did not well reproduce observed flows when comparing to a conventional method simply using a parameter transferred from nearby gauged catchments. This study emphasises that metrics in time dimensions are essential for identifying model parameters and the absence of flow timing information could worsen model performance.