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Evapotranspiration (AETI), Land Cover Classification (LCC), Net Primary Productivity (NPP), Precipitation (PCP), Phenology (PHE), Quality layers (QUAL), Reference Evapotranspiration (RET), Soil moisture (RSM), Total Biomass Production (TBP) and Water Productivity (WP)
Gross and Net Biomass Water Productivity (GBWP & NBWP) data components
The gross biomass water productivity (GBWP) expresses the quantity of output (above ground biomass production) in relation to the total volume of water consumed in a given period (FAO, 2016). By relating biomass production to total evapotranspiration this indicator provides insights on the impact of vegetation development on consumptive water use and thus on water balance in a given domain.
The net biomass water productivity (NBWP) expresses the quantity of output (above ground biomass production) in relation to the volume of water beneficially consumed (by canopy transpiration) in the year, and thus net of soil evaporation. Contrary to gross water productivity, net water productivity is particularly useful in monitoring how effectively vegetation (and, more importantly, crops) uses water to develop biomass (and thus yield).
WaPOR data component
Gross biomass water productivity is calculated and made available through WaPOR on seasonal basis at level 2 and level 3.
Table x: Overview of Biomass Water productivity data components
| Data component | Unit | Range | Use | Temporal resolution |
|---|---|---|---|---|
| GBWP | kg/m³ | 0 to 6 (values observed in WaPOR study area, theoretical range could go up to 25) |
Measures quantity of dry biomass output in relation to consumptive water use | seasonal (further aggregated to user-defined) |
| NBWP | kg/m³ | 0 to 6 | Measures quantity of dry biomass output in relation to transpiration (or beneficial water consumption) | annual |
Methodology
The calculation of gross biomass water productivity is as follows:
where TBP is Total Biomass Production in kgDM/ha. E is evaporation, T is transpiration and I is interception, all in mm.
Calculating GBWP requires input from above ground biomass production, evaporation, transpiration and interception and phenology if calculated on seasonal time step.
The calculation of net biomass water productivity is as follows:
where TBP is Total Biomass Production in kgDM/ha and T is transpiration in mm.
Calculating GCWP requires input from phenology, above ground biomass production, harvest index as well as actual evaporation, interception and transpiration.
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