PiMapping® Tools

As explained at the previous page, PiMapping® Technology uses different tools to calculate and process. At this website the most important and common ones are briefly explained. Please visit the website of our Competence Center to find out more about our technology and its tools.


WaterWatch, together with partners, has developed the SEBAL algorithm, which stands for Surface Energy Balance Algorithm for Land. Both actual and potential evapotranspiration can be calculated on a pixel-by-pixel basis by solving the energy balance at the earth surface using satellite images. Furthermore SEBAL can calculate the biomass production and soil moisture in the root zone. SEBAL requires spatially distributed, visible, near-infrared and thermal infrared data which can be taken from e.g. Landsat ETM, ASTER, NOAA or MODIS.

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ET Tool

ET Tool has evolved from the successful SEBAL model created by Waterwatch. While SEBAL is unprecedented in its accuracy and high resolution results for river basin studies and crop growth monitoring studies, it was not particularly designed to model large areas. ET Tool produces the same outputs as SEBAL but will do this for large areas, even up to continental scale. ET Tool output is quantitative at discrete space intervals of 250 m to 1 km2 which provides quantitative shortages (mm) due to anomalies in soil moisture, vegetation cover, meteorology and groundwater levels. Output parameters are (among others) actual and potential transpiration, transpiration deficit and biomass production. In contrast to SEBAL, ET Tool is not affected by cloud cover in the satellite imagery. ET Tool’s highest temporal resolution is daily.

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MeteoTool is a physically based distribution model for measured air temperature, wind velocity and humidity at screen height. MeteoTool combines flux-profile relationships (including the Monin-Obukhov Similarity Theory); regression analysis to elevation, radiation, vegetation index and distance to sea; and a geo-statistical distribution method. MeteoTool is capable of distributing instantaneous as well as period averaged values of the meteorological variables.

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