IRRISAT: satellite data for water strategy

Published on 11/06/2024

When water becomes scarce while demand increases, a wise resource management strategy is needed. In Morocco, thanks to the SCO label, the CRTS has been able to host the SAT'IRR platform to help optimize irrigation in near-real time, as a complement to its IRRISAT system. The two systems are based on satellite data, but their approach is different and complementary.

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In recent years, Morocco has been affected by prolonged periods of drought and low rainfall, as shown by these Sentinel-2 images in January 2023 and 2024. Faced with the threat of water shortages, local authorities need tools like IRRISAT to optimise the management of this precious resource. © Copernicus Sentinel-2 Imagery, processed by Copernicus EU

In Morocco, where climate change is weakening the hydrological context, the Department of Agriculture has drawn up a strategy for the supply of drinking water and irrigation. With regard to the latter, the aim is to better manage and rationalize the use of surface and groundwater, and to encourage localized irrigation (drip irrigation).

To support this approach, the Royal Centre for Remote Sensing in Morocco CRTS (Centre Royal de Télédétection Spatiale) has designed IRRISAT, an irrigation monitoring system for diagnosing water consumption, use (efficient or inefficient) and productivity. "Unfortunately, the project stalled for a number of reasons. But when CNES presented us with the SCO, we saw an opportunity to revive and improve this work by combining it with other approaches, particularly that developed by CESBIO, in order to put in place an operational system for producing reliable decision-support indicators", explains Mohammed Faouzi Smiej, Head of the Acquisition and Restitution Department in the CRTS Data Management Division. Two years later, thanks to the SCO label, the SAT'IRR tool has been transferred to CRTS, and greatly improved.

Two complementary systems

"At CRTS, we have developed IRRISAT, a global approach based on an energy balance using thermal infrared data. The system generates four products: estimates of evapotranspiration, biomass, soil moisture and advice on irrigation watering. The IRD's SAT'IRR platform is developing a local approach based on water balance, using Sentinel-2 and Landsat imagery. Creating a synergy between these two platforms will enable us to produce virtually real-time information on water consumption on a daily basis, both locally and globally," explains Mohammed Faouzi Smiej.

This is confirmed by Michel Le Page, IRD research engineer and irrigation specialist at CESBIO: "On a regional scale [Irrisat], monitoring water resources is important for water basin managers who need global indicators on the resource and its impact in terms of productivity. On the other hand, on a local scale [SAT'IRR], it is very difficult to calculate the water balance: we know the rainfall but that's about it. We therefore focus on water inputs and plant evapotranspiration, an important part of the water balance that also enables us to identify trends".

Spatial indicators can be used to objectively assess available resources and optimize their use at every level of need and decision-making:

Farmers, on the scale of their plot(s).
Regional agricultural development offices (ORMVA), at the level of their sector.
Water basin agencies, at basin or sub-basin level.

Irrigation control, a market that's still in its infancy
Thanks to the precision of their irrigation monitoring, IRRISAT and SAT'IRR would be in a position to push ahead with the development of an advanced irrigation recommendation service. CESBIO and CRTS have conducted a survey of farmers in the Haouz region of Marrakech to determine whether such recommendations would be attractive. While it turns out that they are interested in this type of tool, their primary concern is the water itself, followed by the energy needed to pump it. The results are similar to those of the survey carried out every five years in the United States: 90% of American farmers use very simple techniques, such as probing the soil with their hands, looking at their crops and what their neighbours are doing.

Project achievements

IRRISAT

👉Creation of an interface for producing and analyzing products on water consumption and productivity.

The CRTS now has a back-office tool that facilitates the generation, in real time or for an entire agricultural season, of various products and indicators on water consumption and productivity, at different spatial and temporal scales, based on VIIRS, Landsat and meteorological satellite data.

▲ Back-office interface for production and analysis of products and indicators on water consumption and productivity (display of daily ET). © CRTS

▲ Plot map of winter crops in the Gharb irrigated perimeter generated by IRRISAT from a time series of Sentinel-2 images between October 2022 and the end of May 2023. © CRTS

👉Produced on a regional scale from thermal infrared

Under the SCO label, the CRTS teams have worked to improve the reliability of IRRISAT products, in particular to improve the definition of thermal data.

Surface temperatures: enhancement of VIIRS low-resolution thermal data (375 m, left) with Sentinel-2 and Landsat8 data (30 m, right). © CRTS

SAT’IRR

👉 Plot-scale products based on optical imagery

For their part, the CESBIO teams restructured the SAT'IRR software and its platform so that it could be transferred to CRTS. To enable local players to familiarize themselves with the software, a training course was organized at CRTS, followed by another with farmers. As SAT'IRR operates at plot level, CESBIO has also set up a system for monitoring four pilot plots on different representative crops (olives, watermelons, oranges and vines). Designed to validate the model but also to iterate with farmers, these plots have been equipped with instruments for automatically measuring water input and soil moisture.

SAT'IRR interface: the plot is identified on a Sentinel-2 image in the top left-hand corner. To its right, the system retrieves the weather data. Below, the first graph shows the evolution of the various water inputs, the second that of evapotranspiration.

👉See details of the methodology, survey and results on the project page

Outlook

CRTS and IRD are now working to harmonize the input data (weather and satellite imagery) from the two platforms so that they work together. Eventually, a geoweb platform will be used to distribute these products.