This is a new online and mobile phone viewer to explore soil moisture in Desert Locust breeding areas in Africa, the Near East and southwest Asia.
Soil Moisture (SM) is a very good indicator of Desert Locust reproduction potential because locust females select moist sandy areas to lay their eggs so they will hatch and not dry out. While rainfall imagery can be used to estimate soil moisture, it does not account for rain that may fall far from the breeding area and runs off down normally dry wadis to reach the breeding area. In this way, SM can be a more precise indicator of where reproduction may occur.
The Locust Hub Soil Moisture tool covers the entire Desert Locust invasion area. Normally, Desert Locust are found somewhere within this large area, consisting of the semi-arid and arid deserts of northern Africa, the Near East and southwest Asia that receive less than 200 mm of rain annually. This is an area of about 16 million square km and includes about 30 countries. Unusually good breeding conditions often associated with severe weather events and cyclones can cause upsurges and plagues to develop.
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The SM service is systematically updated every 10 days. It offers a high-resolution time series of the previous 12 decades (three months), which is essentially the length of one Desert Locust generation.
Note: FAO encourages the use, reproduction and dissemination of this data. Except where otherwise indicated, data may be copied, downloaded and used for private study, research and teaching purposes, or for use in non-commercial products or services, provided that appropriate acknowledgement of FAO as the source and copyright holder is given and that FAO’s endorsement of users’ views, products or services is not implied in any way.
Using the Viewer
The viewer allows users to easily locate soil moisture instantly on an interactive map in just one place and a few clicks by:
• zooming on a region and panning the map
• point-and-click queries to visualise a time-series
Two slider buttons allow you to select the soil moisture range to display in the locust invasion area. The user can select a decade dating back to three months up to the last one available.
These selectors allow the user to filter the area of interest by mean soil moisture to help identify favourable areas for Desert Locust breeding. The “compare” function includes an intuitive search system that clearly displays a comparison of soil moisture differences between two selected decades. This indicates whether the soil is drier (red) or wetter (blue) against the decade the user is comparing to.
Additionally, an API and data access service are available for expert users involved in the monitoring and response to Desert Locust and their impact on food security and livelihoods. You can request access to this API at eclo@fao.org.
The user has the option to easily embed an interactive map on their website, initially displaying the current state of the viewer (position and zoom, decade, rendered SM range, etc.).
Context
The Locust Hub Soil Moisture Viewer is a large-scale operational service that provides SM data at 1 km resolution. It is compliant with the highest standards of usability. The operational service has been developed by
Lobelia Earth for the global Desert Locust early warning system operated by FAO’s Desert Locust Information Service.
Vegetation cover and soil moisture are the two main parameters for estimating the suitability of Desert Locust habitats. While NDVI-based vegetation maps can help Desert Locust managers prioritize surveys and guide teams to potential infestations, the maps might not arrive early enough for planning purposes. On the other hand, SM products should allow Desert Locust managers to plan surveys earlier because soil moisture precedes vegetation growth. One example of using SM is when soil moisture in the Desert Locust habitat increases in an area that is dry, then field surveys should be conducted about two months later to check for locusts and evaluate the need for further preventive action.
The 1 km SM is based on the application of DISPATCH disaggregation methodology to the coarser resolution products obtained from the SMAP satellite mission. The disaggregation is allowed by the relation existing between the Soil Evaporative Efficiency (SEE), defined as the ratio of actual to potential evaporation, and the surface soil moisture.
Further Reading
Cressman, K. (2016). Desert Locust. In: J.F. Shroder, R. Sivanpillai (eds.), Biological and Environmental Hazards, Risks, and Disasters (pp. 87-105). USA: Elsevier.
Escorihuela, M. et al. (2018). SMOS based high resolution soil moisture estimates for desert locust preventive management. Remote Sensing Applications: Society and Environment. Volume 11, August 2018, Pages 140-150. Available at https://doi.org/10.1016/j.rsase.2018.06.002
Hunter-Jones (1964). Egg development in the desert locust (Schistocerca gregaria forsk). Physiol. Entomol., 39, pp. 25-33.
Lazar, M. et al. (2016). Importance of solitarious desert locust population dynamics: lessons from historical survey data in Algeria. Entomol. Exp. Et. Appl., 161 (2016), pp. 168-180.
Pener, M.P. and S.J. Simpson (2009). Locust phase polyphenism: an update. Adv. Insect Physiol., 36 (2009), pp. 1-272.
Piou C,. et al. (2018). Soil moisture from remote sensing to forecast desert locust