Friday, February 7, 1997
FRESH WATER SOURCES THREATENED
text and photographs by Fareed Abou-Haidar
Lebanon as we know it today would not be if it were not for the abundant fresh water that falls on its mountains. The prevailing winds lift water vapor from the Mediterranean sea, then dumps it over the mountains as water condenses and clouds form. The water percolates into the porous limestone, going underground through cracks and sinkholes. Sinkholes are areas where underlying caves have collapsed, forming a pit with no outlet on the surface. The "rooftop" of Lebanon is a huge, relatively flat area with hundreds of sinkholes where deep snow accumulates and melts slowly and, with no outlet, sinks underground. This water eventually finds its way to lower elevations and comes out as springs. Elsewhere, the ground absorbs rain and melting snow; runoff is slowed down by the porous soil and the vegetation (trees, bushes, grass, dead plant matter) covering it. The streams thus run year-round as water is slowly released.
At least that is how it is supposed to be. There are many threats to the hydrology of Lebanon and the water that is so essential to its mere existence. The effects of deforestation (by tree cutting and forest fires) are well documented in Lebanon and elsewhere. The exposed soil is less able to absorb heavy precipitation, and erosion increases. The streams flood after a storm, damaging buildings and roads and spilling valuable topsoil into the sea; in summer, those same streams are bone-dry. It is likely that in ancient times before Lebanon was denuded, all it major rivers and streams ran year-round. Many rivers still flow in places like Arizona that receive even less yearly rainfall than Lebanon; this despite Arizona's own environmental problems.
A lesser known cause of increased runoff and decreased water supply is "pavement". Here, pavement can be defined as any man-made hard surface that water cannot penetrate: asphalt roads, parking lots, buildings... Until recently, this may have been a minor concern. But in the last couple of decades, construction has been rampant in the mountains of Lebanon. A bulldozer clears a thousand meters of land from its vegetation. The land is leveled, and "excess" soil is trucked away and dumped in a drainage below a road somewhere. A building is constructed, and the area around it is paved for parking. Then it rains. Over a season, a meter (1000 mm) of rain can fall in the mountains. That's 1000 cubic meters falling over that building and its parking area; that water immediately drains away and goes to the sea instead of soaking into the ground to replenish water tables and springs. Meanwhile, where the "excess" soil was dumped, the rain erodes some of it away to the sea; the area covered by this disturbed, barren soil is also less able to absorb rain. Multiplied by thousands of similar scenarios across the mountains, it becomes apparent that we have a real problem of degraded watersheds here. This is especially so because much of the construction in the Keserwan area is taking place in areas of very porous karst limestone, in the watershed of Nahr el-Kalb, where much of Beirut's water comes from.
Another threat is rock quarries. Lebanon's huge rock quarries alter water flow and may even disrupt water tables as entire mountains are chopped up. In 1993, there were concerns that the water that flows out of the cave of Jeita and supplies Beirut was being polluted by loose soil from the big rock quarries that have devastated the foot of Mount Sannine (along the road between Darayya and Hamlaya).
In the U.S., where the car-crazed lifestyle has covered many areas in pavement and clear-cut logging has ravaged forests, runoff has become a major problem. Floods causing hundreds of millions of dollars of damage are becoming more common. Many communities have become aware of the problem, limiting the amount of pavement and restoring wetlands.
If the aesthetic concerns of rampant construction and pavement in Lebanon's mountains are not enough, the consequences of winter flooding and summer water shortages should be enough incentive to control further degradation of Lebanon's watersheds. We should not have to resort to purifying sea water as some desert countries have had to do.