A basic and applied remote sensing research project (GRAPEX) for actual evapotranspiration monitoring to improve vineyard water management

Wine grapes are grown world-wide and in many water limited regions. The impacts of climate change causing more frequent and severe droughts and heat waves has made it very challenging for sustainable production and to remain economically viable. A key goal of the GRAPEX (Grape Remote sensing Atmospheric Profile and Evapotranspiration eXperiment) project is developing remote sensing-based methods for monitoring actual vine water use (evapotranspiration, ET) and vine water status to efficiently use and conserve water though improved deficit irrigation practices. To properly develop these methods for vineyards which typically have significant interrow spacing and a managed canopy architecture leading to strongly clumped vegetation with non-uniform vertical distribution of biomass, both basic and applied research is required involving the collection of multidisciplinary data sets. These included leaf-scale gas exchange, water potential and hyperspectral measurements, micrometeorological measurements of energy exchange above and below the vine canopy and in the interrow, biomass and leaf area measurements and soil moisture profile measurements together with tower-based, aircraft and satellite remote sensing data. An overview of the key findings from GRAPEX will be presented from both basic research on understanding soil-vine-atmosphere turbulent exchange processes and applied research efforts in the development of a remote sensing-based ET toolkit for improving irrigation scheduling and water conservation.