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Cartographie de l’intensité du feu et de la sensibilité aux feux de cimes en forêts méditerranéennes. Cas de la province de Chefchaouen au nord du Maroc

2017; Volume: 72; Issue: 4 Linguagem: Inglês

10.3406/revec.2017.1900

0249-7395

Hicham Mharzi Alaoui, Fouad Assali, Mohamed Rouchdi, Driss Tahiri, Saïd Lahssini, Abderrahmane Aafi, Saïd Moukrim,

African Botany and Ecology Studies

Mapping of fire intensity and of sensibility to crown fires in Mediterranean forests. Case of the province of Chefchaouen in northern Morocco. The current evolution of the forest fire regime poses new challenges to the usual practices of forest management plans and forest fires strategies. The implementation of wisely measured actions on the ground in terms of preventive silviculture, water points or fire breaks, requires a deep understanding and a fine mapping of the fire behaviour. This paper focuses first on mapping the fire intensity using the Byram formula in the province of Chefchaouen, one of the most affected regions by this scourge in Morocco. The fire speed of spread is estimated using the parametric equations derived from the physical model FireStar, the spatially varying wind fields according to the relief are carried out by the Windninja software. Secondly, the localization of sensitive areas to crown fires was carried out using the Nelson & Adkins model. The ArcGIS model-builder has been very useful to produce automatically all different maps (intensity map, propagation speed map, flame height, etc.). Results show that almost 55 % of forest areas have a fire intensity ranging from medium to very high (> 1700 Kw/m), among which 11 % with extreme intensity values (over 7000 kW/m). Also the study reveals that 30 % of the forests in the study area are sensitive to crown fires mainly located in zones with flames exceeding 2 m height. On the other hand, the spatially varying wind fields using WindNinja shows that the input wind speed (2.8 m/ s) has almost tripled (7.72 m/s) on 83 % of the territory, and the propagation speed reaches a maximum of 1.5 m/ s (5.4 km/h) on almost 10 % of the forested area.