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

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 1:200.000 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

Rangeland degradation in two watersheds of lebanon

A complex and rugged nature characterizes the Lebanese mountains. The climatic pattern prevailing in the country, deforestation and man made erosion caused increased rangeland degradation. The purpose of this study was to monitor two contrasting watersheds, representing the Lebanese agro-ecological zones, to analyze the vegetation dynamics and trace the state of rangeland degradation. The Kfarselouane [205 km[2] and Aarsal [316.7 km[2]] watersheds are located in the Lebanon and Anti-Lebanon mountain chain and characterized by sub humid and semi-arid climate respectively. Using multitemporal spot vegetation images between 1999 and 2005 to analyze the normalized differential vegetation index [NDVI] revealed some improvement of the vegetation cover over recent years in Kfaselouane with a steady state in Aarsal. The NDVI trend curve inclines in spring and declines in summer and fall. Judging by the time scale amplitude change and highest magnitude between the peak and lower NDVI level in Aarsal, an increased vulnerability to drought is observed in the dry Lebanese areas. Comparing land cover/use in Aarsal area between 1962 and 2000 using aerial photos and large resolution Indian satellite images [IRS] showed wood fragmentation and slight increase of the degenerated forest cover from 1108 ha to 1168 ha. Landuse change was accompanied by a simultaneous increase of cultivated lands [mostly fruit trees from 932 ha to 4878 ha with absence of soil conservation and water harvesting practices. On the contrary, grasslands decreased from 29581 ha to 25000 ha. In Kfarselouane, the area of grassland was invaded by forestland where rangeland decreased from 8073 ha to 3568 ha and woodland increased from 5766 ha to 11800 ha. Forest expansion occurred even at the account of unproductive land which decreased from 2668 ha to 248 ha, while cultivated lands did not reveal any substantial change. Based on animals' seasonal feeding pattern, a mismatch between land carrying capacity and grazing pressure is observed indicating the necessity to develop intermixed irrigated pasture-fruit tree production for supplemental feeding during the dry months

Land cover change over the last 40 years in Lebanon

Land cover change that has overtaken the Lebanese territory in the second half of the twentieth century is mostly expressed by chaotic urban expansion at the expense of agriculture, forestry and natural resources. The 1960's agro-statistics still are a major reference for evaluating any change. This persisted until the 1980's where the areal extent of agro-lands was estimated at 260000 ha while forestry stood at 70000 ha. The crisis events of 1975 to 1990 and the Israeli military aggressions resulted in huge agro and natural cover damage and land degradation. Mismanagement of water supply was an additional aggravating factor. Change detection studies relied on analyzing data from the 1963 agricultural map and the land cover map of 1990's plus updates using Landsat TM and SPOT XS imageries acquired in 1998. Due to the mutli-thematic nature of the landcover, and the complexity of factors influencing change, data were introduced in a GIS system for manipulation. The study shows that there is an overall reduction in agricultural areas varying from 31% in olives, 32.5% in forestry, 35% in citrus, 72% in fruit trees, and 82% in vineyards. Generally, urbanization increased locally anywhere from 25% to more than 100%. The proportions vary among the different provinces influenced by several socio-economic factors. In Beka'a, where most agriculture occurs, the largest land degradation and forest cover removal have taken place. Lebanon has thus far lost about 32% of its forest cover