The Karstic Flow System in Uja Area — West Bank: An Example of two Separated Flow Systems in the Same Area

Abstract

Uja spring is the largest spring in the Eastern Basin of the Judea-Samaria Mountains in the West Bank. In the vicinity of the spring outlet there are three production wells (Uja 2,3,4). The Uja spring is characterized by large discharge fluctuations. It was conjectured that the drying of the spring in dry years is the result of pumping in the nearby Uja wells. This conjecture follows the assumption that the spring and the wells are hydrologically connected and are supplied by the same reservoir.

A detailed investigation of the spring discharge, the hydrological setting of the spring, of the wells and the wells water level measurements, shows that the spring and the wells are hydrologically separated. As a result, the pumping from the wells has no influence on the spring discharge.

There is a local, very karstic aquifer, which feeds the spring; the discharge depends on climatic variations (drought or rainy years). In contrast the Uja wells draw water from a deep, separate, aquifer. A similar hydrological situation exists in the En Samiya area, where the Palestinian Authority utilizes water from the En Samiya spring (Upper aquifer) and from the wells (lower aquifer). The important consequences of this analysis on the management strategy of the water supply of the area are concluded in this paper.