Chemical and biological monitoring in ephemeral and intermittent streams: A study of two transboundary Palestinian-Israeli watersheds

Although ephemeral streams constitute critical natural resources in dryland environments, water regulations and monitoring protocols typically focus on perennial streams, and may not always be appropriate for characterizing intermittent systems. The article presents findings from a comprehensive evaluation of environmental conditions in two ephemeral transboundary streams: the Hebron/Besor and Zomar/Alexander. The streams are representative of numer-ous watersheds which originate in Palestinian land and flow into Israel. Transboundary streams in the region exhibit high concentrations of point and non-point sources of pollution. Many of the region's streams that in the past had no flow except for isolated storm incidents have emerged as perennial streams, channelling raw or partially treated industrial or municipal wastes. Management of these natural resources constitutes a unique challenge because of the complex local political circumstances. The article presents chemical and biological monitoring results, identifying high levels of non-point source nutrient runoff during rainfall events and high percolation of contaminated streamwater during its flow that should be addressed in future restoration strategies. The practical challenges associated with the monitoring of ephemeral streams are also discussed with suggestions for future studies and management efforts.