Use of remote sensing and gis to assess the anthropogenic impact on forest fires in Nahr Ibrahim watershed, Lebanon

ABSTRACT

The Mediterranean forests are exposed yearly to several forest fire events threatening the social, economical, ecological and living conditions of human being. The majority of these fires are of anthropogenic origin. The Nahr Ibrahim watershed [NIW] represents a typical example of the Lebanese areas having abundant forest surface [38.23% of its surface] but suffering recently from forest fires. The preservation of these natural resources is a priority for the continuity, stability and prosperity of the country. Several methods were applied to evaluate the potential forest fire risk in order to identify hot spots and reduce the potential damage. In this context mapping forest fire risk is a priority and a preliminary tool for the prevention of catastrophic fire events and development of sustainable forest management plans. The use of remote sensing and GIS provided the solid base for similar studies such as the forest fire risk map done for Lebanon at 1200.000 scale. Therefore, the need for more detailed analysis at the watershed level arises. In this study a comparative analysis was conducted at a large scale [1 50.000] on the NIW to assess the effect of several natural factors [climate, topography, vegetation and soil conditions] on forest fire risk. A combination of natural and anthropogenic factors [urban settlements, roads and zones with agricultural activity] provided better understanding of the impact of anthropogenic activities on forest hazards and forest resources conservation. The results show that forest fire in high risk zones is aggravated by anthropogenic activities an increase from 5% to 38% was detected. In areas of moderate risk the increase goes from 7 to 25%. On the other hand, areas with low risk zones noticed a significant decrease when the anthropogenic activities were incorporated. Areas with very low risk have almost vanished