Earth Observations for Water Resources Management

Earth Observations became gradually an inevitable component to assess various water flows and fluxes. The data character allows to observe various key physical land surface processes in a distributed and indirect manner. The information has an independent character, which is of essence to solve transboundary water management conflicts. Because every pixel is a unique measurement in the space and time domain, it allows to understand what is happening at that discrete piece of land. Every “pixel is talking”, and international academic research has contributed to detect and understand this language. The Department of Water Management of TU Delft is actively contributing to these developments. Soil moisture and evaporation are typical topics that we cover. While ESA and NASA chose to invest in large scale passive microwave technologies, TU-Delft has developed with partners methods to compute soil moisture in the root zone on a grid of 30 m using thermal images. Subsoil root zone is more relevant to detect local vegetation growing conditions and facilitate irrigation scheduling. Below is an example of the Bekaa Valley in Lebanon.

Sub-soil volumetric soil moisture, 7 July 2014
Subsoil volumetric soil moisture, 12 November 2014

Source: SPIE conference Edinborough, Bastiaanssen and Van Opstal (2016)

Source: Simons, Poortinga, Bastiaanssen, Hessels et al. (2017)

The availability of remotely sensed spatial data sets in hydrology and water management is forming the core for a new water accounting system that was introduced at TU by the inaugural lecture of Professor Bastiaanssen in 2009. Water Accounting Plus (WA+) became in the meantime one of the leading systems to report on the water resources conditions in river basins. It is currently endorsed by FAO and Asian Development Bank, and taken up by World Bank to assess loans and grants in the international water sector.  More information can be found at