A new flexible hydrological framework for land surface modeling in regional and global climate studies

Global landsurface processes play an important role in the land-atmosphere exchanges of energy, water, and trace gases. The increase in computational power nowadays enables us to more accurately represent important small scale hydrological processes (e.g. hillslope response, lateral groundwater flow, unsaturated/saturated zone interaction, and channel network interaction).

So far, for regional and global climate studies most land surface models make use of a conceptual hydrological representation. As such, these models do not specifically define the interactions between the different hydrological states within a given model grid cell (i.e. hillslope, riparian zones, wetlands) as well as the lateral exchange between grid cells.

We present a new pseudo three-dimensional (3-D) framework that is able to simulate the lateral exchange of water between hillslopes, the riparian zone, wetlands, the channel network, within a given model grid cell, and across cells. Instead of applying the traditional conceptual approach, the interaction within and between the different hydrological components was incorporated using a physically based approach based on much finer resolution pixels (e.g., 1 km) than the parent regional/global climate model grid cells.

The newly developed framework proposes a compromise between the ability to accurately simulate high resolution hydrological processes and the current computational constraints. As such, our framework can be used for high-resolution land surface modeling (~1km2) but can also flexibly scales to lower resolutions.

In this presentation, we will discuss this new framework and its preliminary evaluation over a watershed in comparison with various land surface models.