Case studies
Drought Monitoring in Mali
Retrieval of soil moisture.
Approach for soil water and crop modelling
Discussion of results

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SCATMALI: Drought Monitoring in Mali 1997-1999

This is a summary of the work done to in the framework of the ESA Data User Programme 1997 project: for an "Application Service Demonstrator for Drought Early Warning in Mali Based on Scatterometer Information".

The overall objective of the project is to develop this 'demonstrator' and to run and evaluate it for the growing season of 1998 in Mali. A number of tasks have to be performed to do this:
* To adapt and develop suitable concepts to retrieve soil moisture information from ERS-scatterometer data over Mali;
* To use these remotely sensed soil moisture measurements as crop performance indicators for various soils and crops;
* To validate, demonstrate and evaluate these indicators in Mali
* To formulate an outline for a business perspective for the application.

This ambitious project has been executed by a project team with the following responsibilities:
* Technical University of Vienna, Institute of Photogrammetry and Remote Sensing in Austria responsible for retrieval of soil moisture information from scatterometer data;
* Catholic University of Leuven, Institute for Land and Water Management in Belgium responsible for the agro-climatological analysis, the crop modelling approach utilising the scatterometer data and the development of indicators for cropping conditions and planting dates;
* The Institute for Rural Economy, Laboratory for Soil Water and Plants with the Regional Agronomic Centre in Bamako, Mali responsible for field data collection and validation of preliminary results;
* NEO, Netherlands Geomatics & Earth Observation B.V., from Amersfoort, The Netherlands, responsible for the overall project management, the integration of the soil moisture information, the indicators for cropping conditions, and databases for soils, climate and field data in a GIS-environment to be run under semi-operational conditions.

The project was performed in two phases. In the first phase historical data were collected and processed for scatterometer observations in the period 1991 - 1997. Historical rainfall data were processed for 13 stations with records over the past 47 to 75 years, and a soil and crop database was established for Mali. Rainfall based and rainfall-evaporation based water balance simulations were compared to scatterometer derived soil moisture and scatterometer-based water balances over 5 years. Crop planting and crop performance indicators were developed utilising the scatterometer derived soil moisture data. In the second phase all scatterometer measurements were collected during the growing season of 1998. Weekly averages were calculated. At the end of every week these data were communicated to Mali and published on the Internet. A field campaign was conducted for 6 locations on different moments during the season. Another extensive survey amongst people involved in agriculture in different ways, has led to a very large database with crop and cropping information.

Mali is a land-locked country in Western Africa. The project area stretches between 2DE and 12D W, 10D to 17DN, a zone covering approximately 1 million km2. The project area covers a wide range of climatic and physiographic conditions between the humid Guinean agro-climatic zone to the Sahara desert. The area of main interest is the principal crop production zone in West Africa between the northern Sahel and the southern Sudan agro-climatic zones. Initially it was assumed that the vegetation density in southern Mali would be too high to retrieve information on soil information through the thick canopy. However when it turned out that over this area also relevant information was obtained, the area along Mali's southern border was also included.