Authors: Aniket Gupta, Ali Behrangi, Guo-Yue Niu – University of Arizona
Title: Developing a plant hydraulics module compatible with BMI of the NextGen Framework
Abstract: Plant transpiration is the largest component of evapotranspiration (ET), especially in the riparian zones over drylands. Plant dynamics in response to changes in hydroclimatic conditions contribute substantially to the seasonal and inter-annual variability in plant transpiration and hence ET. However, the representation of plant dynamics is inappropriate in the state-of-the-art hydrological models, resulting in high transpiration biases under dry conditions due to lack of representations of plant hydraulics (e.g., pressure-driven root water uptake). The Next Generation Water Resource Modeling Framework (NextGen) allows the coupling of different hydrological modules in the single framework through Basic Model Interface (BMI). Currently, for surface energy and water flux exchanges, NextGen relies on Noah-OWP-Modular, a simplified and modularized version of the Noah-MP Land Surface Model. Subsurface hydrology and runoff routing are further simulated using the Conceptual Functional Equivalent (CFE) and T-route modules, respectively. However, Noah-OWP-Modular does not account for plant dynamics and hydraulics, which are essentially helpful for improved modeling of water resources under a changing climate (e.g., droughts). We, at the first step, have been developing a module of dynamic root water uptake to improve the modeling of ET components under a NextGen configuration of CFE+Noah-OWP-Modular+T-route. We will further test a module of root, stem, and leaf dynamics based on carbon budgets (photosynthesis and respiration) to enhance the overall performance of NextGen’s modeling of plant transpiration component, especially under water-stressed conditions.