Two-way coupling between the sub-grid land surface and river networks in Earth system models

Abstract

Abstract. Over the past decade, there has been appreciable progress towards modeling the water, energy, and carbon cycles at field-scales (10–100 m) over continental to global extents. One such approach, named HydroBlocks, accomplishes this task while maintaining computational efficiency via sub-grid tiles, or Hydrologic Response Units (HRUs), learned via a hierarchical clustering approach from available global high-resolution environmental data. However, until now, there has yet to be a macroscale river routing approach that is able to leverage HydroBlocks' approach to sub-grid heterogeneity, thus limiting the added value of field-scale land surface modeling in Earth System Models (e.g., riparian zone dynamics, irrigation from surface water, and interactive floodplains). This paper introduces a novel dynamic river routing scheme in HydroBlocks that is intertwined with the modeled field-scale land surface heterogeneity. The primary features of the routing scheme include: 1) the fine-scale river network of each macroscale grid cell's is derived from very high resolution (

Peak Runoff Timing Is Linked to Global Warming Trajectories

“…Therefore, suitable simplifications (known as "parameterizations") of processes (e.g., surface and groundwater flow, snow) and/or controlling factors (e.g., topography, soil structure, landuse) continue to be necessary for GCMs. Correspondingly, recent developments targeting to improve the representation and realism of hydrological physical processes in land-surface models have included surface water dynamics (Ekici et al, 2019), land-river interactions (Chaney et al, 2020;Decharme et al, 2019), parameterizations of sub-grid topography (Tesfa et al, 2020), variable soil thickness (Brunke et al, 2016), and variably saturated flow dynamics XU ET AL.…”

“…Therefore, suitable simplifications (known as “parameterizations”) of processes (e.g., surface and groundwater flow, snow) and/or controlling factors (e.g., topography, soil structure, landuse) continue to be necessary for GCMs. Correspondingly, recent developments targeting to improve the representation and realism of hydrological physical processes in land‐surface models have included surface water dynamics (Ekici et al., 2019), land‐river interactions (Chaney et al., 2020; Decharme et al., 2019), parameterizations of sub‐grid topography (Tesfa et al., 2020), variable soil thickness (Brunke et al., 2016), and variably saturated flow dynamics with groundwater (Bisht et al., 2018). While comprehensive offline assessments have been carried out, these developments have not yet been directly implemented in GCMs; further studies are necessary to better understand the sensitivity (Dwelle et al., 2019) of the modeled runoff dynamics to the inclusion of new parameterizations and their parameters.…”

Impacts of Fully Coupling Land Surface and Flood Models on the Simulation of Large Wetlands' Water Dynamics: The Case of the Inner Niger Delta

“…The large majority, however, represents surface water dynamics through very simplified schemes and overcomes the limited representation of floodplains by using coarse spatial resolutions from 0.125° to 1°. There is a consensus that better surface water parameterizations are needed for a more accurate representation of interactions between wetlands and the land surface (e.g., Chaney et al., 2020; Miguez‐Macho & Fan, 2012b). Using the local inertia formulation in HyMAP allowed us to represent wetland dynamics at a significantly finer spatial resolution (i.e., 0.02°) and the spatially distributed impacts on the water and energy balances.…”

“…At a finer scale, Chaney et al. (2020) described a two‐way coupling implementation at ∼1 km spatial resolution, accounting for sub‐grid information through hydrological response units. The vertical water and energy balances are computed using the Noah LSM with Multiparameterization options (Noah‐MP; Niu et al., 2011) and the horizontal water redistribution through the kinematic wave equation.…”

“…More recently, using the Organizing Carbon and Hydrology In Dynamic Ecosystems (ORCHIDEE) LSM (Krinner et al, 2005) at 0.5°, Schrapffer et al (2020) articulate the importance of representing large tropical floodplains in Pantanal in two-way coupled model simulations to improve their capacity in reproducing fluxes and land surface conditions. At a finer scale, Chaney et al (2020) described a two-way coupling implementation at ∼1 km spatial resolution, accounting for sub-grid information through hydrological response units. The vertical water and energy balances are computed using the Noah LSM with Multiparameterization options (Noah-MP; Niu et al, 2011) and the horizontal water redistribution through the kinematic wave equation.…”