The snowmelt of Mt. Hermon and its contribution to the sources of the Jordan River

Abstract

The water resources of the upper Jordan River Basin, particularly the main springs, are partially fed by the snowmelt of Mt. Hermon. Mount Hermon is an uplifted anticline extending along the northern border of Israel, and covering an area of ∼ 1200 km 2, of which 750 km 2 is included in the Jordan River watershed. Most of Mt. Hermon is composed of karstic limestone of Jurassic age, > 2000 m thick. The annual amount of precipitation over the Jordan River sources watershed is estimated to be 8.5 × 10 8 m 3. The water yield of the Jordan tributaries is 5 × 10 8 m 3, with 4 × 10 8 m 3 of it being discharge from karstic springs. To date, there are almost no data or estimates of the magnitude of snowmelt recharge and its areal and temporal distribution. Inaccessibility to most parts of the mountain is the main reason for the lack of data. During the last four years research has been conducted to find characteristic parameters that represent the relationship between the Mt. Hermon snowcover and its contribution to dry weather discharge of the Jordan River tributaries. Snow depth and water content were measured at several locations in the altitude range 1500–2100 m above sea level (a.s.l.). The snow-covered area was obtained from Landsat images and from aerial photographs. The snow lines were delineated on 1:250 000 scale maps and their area was measured. These data were compared with the dry weather water yield of the Jordan tributaries and the main springs. Significant contribution from the snowpack was found only above 1400 m. The areal extent of the pertinent snowcover is 185 km 2, representing about 25% of the total drainage basin of the Jordan head waters. The mean water content at the snow gaging sites increased from 10 cm at an elevation of 1500 m–65 cm at an altitude of 2100 m a.s.l. Based on these values, a preliminary estimate yielded a volume of 5 × 10 7 m 3, which is about 30% of the dry weather discharge. This may be considered as the potential snowmelt recharge to the Jordan River main springs.