Peat hydrology in the Hula Basin, Israel: II. Subsurface flow regime

The subsurface flow regime in the drained portion of the Hula Basin has been investigated on a local and regional scale. The results are based on data obtained largely from a three-dimensional network of piezometers and observation wells covering the entire drained area, and another three-dimensional network covering a representative experimental plot. The data include measurements of piezometric levels under various conditions, analyses of stable and radioactive environmental isotopes in water samples from various depths and chemical analyses of water. It is shown that the position of the water table is controlled by the local topography. The groundwater at depths exceeding 2 m below the surface is subject to a mild regional hydraulic gradient from north to south, and a much more pronounced vertical gradient upward. The upwelling groundwater is probably derived from recharge over the surrounding mountains. When the groundwater reaches the water table it mixes with waters originating at the surface, discharges into the channels and ditches which cross the drained area, and is carried downstream into the Jordan River. One of the important conclusions of this study is that water originating at the surface has practically no chance of reaching a depth exceeding 2-3 m.