Sustainable Land and Water Management in North Africa

The Sahara and Sahel Observatory is the leader of a project dedicated Sustainable Land and Water Management in North Africa: "Funded by the European Union through the Commission of the African Union, the "Support Project for the Sustainable Management of Water and Natural Resources through the Exploitation of Earth Observation Data and Technologies" of the GMES & Africa Program, aims to support decision making in the field of sustainable management of water and natural resources through the provision of products and services developed from the data and Earth Observation techniques."

The project "Earth Observation for Sustainable Land and Water Management in North Africa" is implemented by OSS (Sahara and Sahel Observatory), with the support of its national and regional partners in charge of remote sensing, namely ASAL (Algeria), DRC (Egypt), LCRSSS (Libya), CRTS (Morocco), University of Nouakchott (Mauritania) and CNCT (Tunisia) for the national level and CRTEAN and CRAST-LF for the regional level.

The services to be developed by the project are:

• Agricultural seasonal monitoring and Early warning,
• Water abstraction assessment and monitoring water use in irrigated areas,
• Land degradation monitoring.

Delivered by African EO Services, the MISBAR platform (Monitoring Integrated Services for Best Assessment for natural Resources) allows to monitor vegetation along time crop by crop in vast areas, allowing precision agriculture to optimise water in regions where the water resource is sometimes scarce.

In this Saharian area, some crops are grown in an oasis. These plots show in blue on the soil moisture index above. The precipitations are concentrated during the second half of the year. It does not correlate well with the soil moisture computed along time by Sentinel-2 during from 2018 to 2020. It suggests these date palm trees are not rain fed. The indices are similar all three years showing the soil moisture and the vegetation growth are maximal during the winter months.

These crops benefit from the Senegal river nearby. The soil index and the vegetation index are closely matched. The second crop of the year follows the precipitations with several weeks of delay. The first crop happens at a period of no significant precipitation which implies it is irrigated.

The precipitations, soil moisture and vegetation indices all show good concordance and similar shape from 2018 to 2020.

These graphs show good agreement for 2018 and 2020 but year 2019 (green) seems significantly different regarding precipitations, soil moisture and vegetation indices. This anomaly is coincident with a lower production for this plot in 2019.

This plot uses center pivot irrigation and does not rely on precipitations for its growth that precedes the rainy months. The year 2019 and 2020 are closely matched but there is neither humidity nor vegetation detected on the area of interest in 2018 (black). It is because the farming of this plot started in early 2019.

These graphs show good agreement for 2018 and 2019 but lower precipitations in 2020 (red) that resulted in lower measures of soil moisture and vegetation indices the same year. This anomaly can be linked to a lower yield for this plot in 2020.