Material Loads from the Jordan River

Abstract

The Jordan River is a major source of water, solutes, and allochthonous particles to Lake Kinneret contributed by the river tributaries as well as through leaching and erosion of soils and leakage of effluents. Those external nutrient loads impact the Lake Kinneret ecosystem. The current chapter presents a processed time series of material loads for 1971–2012 based on discharge measurements at the “Pkak Bridge’’, located on the Jordan River downstream of all tributaries and the Hula Valley. Also presented are chemical analyses performed on water samples collected at the same place. During the early 1990s, water sampling was gradually changed from being manual to an automatic sampling method, with an overlap period from 1991 to 1996 during which both methods were widely applied. Discrepancies between the two sets of parallel data obtained during the years of overlap were analyzed, with conclusions used to produce a single coherent corrected long-term record. Robust trend analysis performed on the corrected time series revealed significant long-term declines in the loads of nitrogen and phosphorus compounds, and suspended matter, while total nitrogen to total phosphorus ratio remained unchanged. The time series also reflects a wide range of anthropogenic activities in the watershed, such as increasing population and effluents in the 1970s, the peat area reclamation by the “Hula Project” since 1994, and the various watershed management actions implemented to vigorously eliminate pollution sources in the Lake Kinneret watershed.