4Crop web application for monitoring rain-fed crops in the Sahel

Agro-geoinformation is the key information in the agricultural decision making and policy formulation process, specially in the countries where food security mainly depends on rain-fed crops production. It's the case of Sudano-Sahel zone where scarce economic resources hamper regular monitoring of crops development; a context that requires new approaches to detect crops risk zones during the agricultural season. The advances of Earth observing and sensing technologies, as well as geoprocessing web tools, enable new opportunities and challenges in applying agro-geoinformation to crop monitoring and assessment. As a matter of fact, in this Region web-based geoprocessing has not been yet fully explored for agricultural applications, whilst stand-alone applications and software are still widely used. Especially in LDCs, stand-alone applications, without continuous user support and updates, makes the analysis and the application of geospatial data very expensive and time consuming. Moreover the unavailability of timely meteorological data and the scarcity of funds for hardware and software maintenance, do not ensure near real-time drought monitoring on regular basis by National Early Warning Systems (EWSs) for food security. This paper presents the "4Crop" web application, an open source and interoperable solution to meet the needs for a long-term sustainability of operational tools for drought risk identification and forecasting in the Sahelian countries that balances the lack of sufficient and timely acquisition of ground data using meteorological satellite open data sets. The goal is to support Sudano-Sahel Early Warning Systems and any other local users in decision making and foster drought risk reduction and climate change resilience. The 4Crop client/server architecture has been implemented using open source tools and standards in order to guarantee the web application sustainability and the implementation of customized geospatial functions required by the end users. Furthermore the user interface has been designed following a user centred approach to respond to user needs. The whole web geoprocessing is based on the Crop Risk Zone (CRZ) model. The model performs a soil water balance to evaluate the satisfaction of crop water requirements in each phenological stage of the growing period. The 4Crop application running at present on Niger and Mali, has been implemented using PL/pgSQL & PostGIS functions to process different meteorological data sets: a) the rainfall precipitation forecast images from Global Forecast System (GFS) b) the Climate Prediction Center (CPC) Rainfall Estimation (RFE) for Africa c) Multi-Sensor Precipitation Estimate (MPE) images from EUMETSAT Earth Observation Portal d) the MOD16 Global Terrestrial Evapotranspiration Data Set. The 4Crop outputs aim to identify installation and phenological phases of the main rain-fed crops (millet, sorghum, groundnut, cowpea) and to create crop risk zones images for each country selected. The model also provides a qualitative evaluation of the expected yield of crops compared with the potential one, as a consequence both of the water stress intensity and phenological stage of crops. The approach here proposed is meant to encourage the integration and sharing of interoperable and open source solutions and thus contribute to the setting-up of distributed climate services in developing countries