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Eratos SFM Water Usage Workflow

The EratosSFM Water usage workflow provides cloud based computation and display of tree and plant water use from the SFM1x Sap Flow Meter.

The SFM1x directly measures sap velocity in the plant xylem (cm/hr) using the established Heat Ratio Method (HRM), which when multiplied with correction factors for wounding and probe alignment gives the Corrected Heat Pulse Velocity (cm/hr). Corrected Sap Velocity (cm/h) can then be derived from Corrected Heat Pulse Velocity multiplied by a factor related to the densities and specific heat capacities of both wood and sap.

With knowledge of the tree’s physical dimensions (i.e., circumference, bark depth and sapwood depth) the relevant sized area(s) of sapwood can be calculated (in accordance to measurement points and remaining area). By combining these areas, with the corrected sap velocities derived from measurements at different probe depths, the Sap Flow (kg/h) can be calculated and by averaging a group of successive measurements.

The EratosSFM workflow outputs total hourly tree water usage in litres, daily and cumulative water usage totals are then easily visualised in the Eratos Viewer platform.

For crop management the EratosSFM Water Usage workflow can optionally be used alongside the EratosETo workflow for calculation of evapotranspiration (FAO Penman-Monteith)