04/01/2015
Evaluating Global Streamflow Simulations by a Physically-Based Routing Model Coupled with the Community Land Model
Summary
Streamflow is a key component of the terrestrial system. By redistributing water and the associated heat content and nutrients through the hillslope, tributary, and stream network, streamflow plays an important role in the regional and global water, energy, and biogeochemistry cycles of the Earth system. To improve streamflow modeling in Earth system models (ESMs), Department of Energy (DOE) scientists at Pacific Northwest National Laboratory (PNNL), with collaborators at the National Aeronautics and Space Administration’s Goddard Space Flight Center and University of Maryland, evaluated the global implementation of the Model for Scale Adaptive River Transport (MOSART) recently developed at PNNL and coupled with the Community Land Model (CLM4.0). To support global modeling using MOSART, a comprehensive global hydrography dataset was derived at multiple resolutions from different sources. The scientists first evaluated the simulated runoff fields against the composite runoff from the Global Runoff Data Center (GRDC). With routing of the runoff from CLM by MOSART, the simulated streamflow reproduced reasonably well the observed daily and monthly streamflow at over 1,600 major world river stations in terms of annual, seasonal, and daily flow statistics. The scientists also evaluated the impacts of model structure complexity. Results showed the spatial and temporal variability of river velocity simulated by MOSART is necessary for capturing streamflow seasonality and annual maximum flood. Other sources of simulation biases include uncertainties in the atmospheric forcing, as revealed by simulations driven by four different climate datasets, and human influences, based on a classification framework that quantifies the impact levels of large dams on the streamflow worldwide. In addition to simulating streamflow, MOSART provides a physically based global framework for modeling stream temperature and river biogeochemistry, both currently under or not represented in ESMs.
Funding
This work was jointly sponsored by DOE’s Earth System Modeling and Integrated Assessment Research programs.
References
Li, H.-Y., L. R. Leung, A. Getirana, M. Huang, H. Wu, Y. Xu, J. Guo, and N. Voisin. 2015. “Evaluating Global Streamflow Simulations by a Physically Based Routing Model Coupled with the Community Land Model,” Journal of Hydrometeorology 16(2), 948–71. DOI: 10.1175/JHM-D-14-0079.1.