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 online river-routing scheme into the regional climate model (RCM) framework as a unified subroutine module and investigated the sensitivity of simulated river flows in response to changes in spatial resolutions in RCM and river-routing scheme. The river-routing scheme gathers runoff from the RCMand advects them horizontally along the river drainage network. The dynamical downscaling simulations were driven by reanalysis at the boundaries for the period of 2000–2010, using different grid sizes for RCM (50 and 12.5 km) and for river-routing scheme (0.5°, 0.25°, and 0.125°). Simulated river discharge was evaluated throughout the three largest river basins 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 the resolution sensitivity experiments, it was confirmed that high-resolution RCM enhances the reproducibility of river discharge; however, the lack of sophistication of the current river-routing scheme, which was originally developed for continental and macroscale application, mitigates taking advantage of enhanced resolution in river model. On the basis of our findings and experiences in this study, we revealed several considerable issues for future developments of river simulation in the RCM framework.