Evaluating and Improving Water Runoff in the Community Land Model
To simulate the exchange of water and energy between the ground and the atmosphere, the flow of water over and through the land surface must be accurately simulated. DOE-funded scientists at Pacific Northwest National Laboratory and Oak Ridge National Laboratory and a collaborator from the Chinese Academy of Sciences tested the simulation of water flow in the Community Land Model (CLM4) by comparing model simulations of runoff, surface water, and energy flux at various locations using streamflow gauge measurements from the U.S. Geological Survey and measurements from various flux towers across North America. The original model predicted excessive runoff variations that are not realistic when compared to observations. The team demonstrated that hydrologic simulations from CLM4 might be improved by calibrating the model parameters to better approximate actual site conditions. In addition, they showed it is important to represent spatial heterogeneity in land cover, vegetation, soil, and topography for better simulation of streamflow by increasing the spatial resolution when applying the model to a mountainous watershed. The research demonstrates the important constraint of soil hydrology on the surface energy budget and highlights the need to improve runoff parameterizations in land and surface models. The team identified several methods to improve the simulations, mainly by improving how the subsurface runoff is parameterized.
Li, H., M. Huang, M. S. Wigmosta, Y. Ke, A. M. Coleman, L. R. Leung, A. Wang, and D. M. Ricciuto. 2011. “Evaluating Runoff Simulations from the Community Land Model 4.0 Using Observations from Flux Towers and a Mountainous Watershed,” Journal of Geophysical Research – Atmospheres 116, D24120, DOI:10.1029/2011JD016276.