The GEOframe Soil Plant Atmosphere Continuum Estimator (GEOSPACE) to investigate the vadose zone processes

<p>This contribution illustrates the GEOframe Soil Plant Atmosphere Continuum Estimator (GEOSPACE). It is the ecohydrological model of the GEOframe system and it wants to simulate the soil-vegetation-atmosphere interactions to study and analyze the complex processes that occur in the Earth Critical Zone (CZ). The CZ is defined as the “heterogeneous, near surface environment in which complex interactions involving rock, soil, water, air, and living organism regulate the natural habitat and determine the availability of life-sustaining resources”.</p><p>GEOSPACE is a coupled model in which the three major components are WHETGEO, GEO-ET and BrokerGEO. WHETGEO, Water Heat and Transport in GEOframe, (Tubini N. and Rigon R., 2021), solves the conservative form of Richardson-Richards equation using the Newton-Casulli-Zanolli algorithm (Casulli V. and Zanolli P., 2010) that guarantees the convergence at any time step, and the proper transition from unsaturated condition to saturated one. Besides it deals seamlessly the surface water ponding. WHETGEO also implements the numerical solution shown in Casulli and Zanolli (2005) to solve the advection-dispersion equation and describe the solute transport. GEO-ET, EvapoTranspiration in GEOframe, computes evapotranspiration according to three different formulations, the Priestley-Taylor model, Penman FAO model and GEOframe-Prospero model (Bottazzi, 2020), by considering Jarvis model (Macfarlane et al., 2004) and Ball-Berry-Leuning model (Lin et al., 2015) to compute environmental and water stress factors. BrokerGEO is the coupler component that allow the exchange of data between the other two components in memory and considers the root water uptake for the computation of the actual evapotranspiration. The GEOSPACE model was tested with the lysimeter of the “Spike II” experiment (Nehemy et al., 2019; Benettin et al., 2021) of the Ecole Polytechnic Federal de Lausanne. The analysis we carried out with GEOSPACE concern the flux partitioning of precipitation and irrigation water into evaporation and transpiration; the soil water and groundwater storage; the transport of water stable isotopes through the soil. In this research we present them and show how GEOSPACE can be used to test hypotheses on the links between the plant water status and its isotopic signatures.</p><p>GEOSPACE is developed in Java using the Object-Oriented programming paradigm and it is completely open source, available on the GEOframe GitHub website. The code organization and its functionalities besides solving the hydrological issues are designed according to principle of open science to be inspectable and verified by third parties.</p>