Development and implementation of river-routing process module in a regional climate model and its evaluation in Korean river basins

Abstract

This study assessed the potential for river discharge simulation by implementing an onlineriver-routing scheme into the regional climate model (RCM) framework as a unified subroutine moduleand investigated the sensitivity of simulated river flows in response to changes in spatial resolutions in RCMand river-routing scheme. The river-routing scheme gathers runoff from the RCMand advects them horizontallyalong the river drainage network. The dynamical downscaling simulations were driven by reanalysis at theboundaries for the period of 2000–2010, using different grid sizes for RCM (50 and 12.5 km) and for river-routingscheme (0.5°, 0.25°, and 0.125°). Simulated river discharge was evaluated throughout the three largest riverbasins in Korea. The simulation results showed potential for river discharge modeling in the RCM framework.The model generally captured the seasonal and monthly variabilities, and the daily scale peaks. From theresolution sensitivity experiments, it was confirmed that high-resolution RCM enhances the reproducibility ofriver discharge; however, the lack of sophistication of the current river-routing scheme, which was originallydeveloped for continental and macroscale application, mitigates taking advantage of enhanced resolution inriver model. On the basis of our findings and experiences in this study, we revealed several considerable issuesfor future developments of river simulation in the RCM framework.