Morphological changes in the last 200 years in the mouth of the Na'aman River, northern coastal plain, Israel

The Na'aman River mouth is located in Haifa Bay, at the northern end of the Nile littoral cell of Israel's Mediterranean coast. This study documents the morphological changes to this river's mouth over the last 200 years based on three historical maps from 1799 to 1930 as well as a series of 54 aerial photographs taken between 1945 and 2005. Mapping of morphological features and vegetation cover in the vicinity of the changing mouth was performed with a Geographic Information System (GIS); quantitative and qualitative parameters were derived from this mapping.The temporal and spatial patterns of the mouth migration were characterized and factors influencing its morphology such as vegetation cover, stream discharge, wave regime, and anthropogenic changes were analyzed.The Na'aman River mouth intermittently flows in a permanent channel along the back of the north-south beach berm. The channel remains stable for several years until a major flood diverts it. The mouth migrated 1.5 km, both north and south, along the coast during the last 200 years, about equally in either direction. An increase in vegetation cover over the years restricted the migration of the channel. River floods may cause the "resetting" of the mouth morphology and its location, but if the channel is robust, even large floods are unable to divert it. Wave direction does not seem to affect the deflection of the channel. Anthropogenic intervention in the natural course of the mouth took place in two ways: artificial opening of the mouth to prevent flooding hazard and control the mosquito habitat, and channel diversion intended to prevent the pollution of nearby bathing beaches.