Quantifying Ground Water Inputs along the Lower Jordan River

Abstract

The flow rate of the Lower Jordan River has changed dramatically during the second half of the 20th century. The diversion of its major natural sources reduced its flow rate and led to drying events during the drought years of 2000 and 2001. Under these conditions of low flow rates, the potential influence of external sources on the river discharge and chemical composition became significant. Our measurements show that the concentrations of chloride, calcium, and sodium in the river water decrease along the first 20-km section, while sulfate and magnesium concentrations increase. These variations were addressed by a recent geochemical study, suggesting that ground water inflow plays a major role. To further examine the role of ground water, we applied mass-balance calculations, using detailed flow rate measurements, water samplings, and chemical analyses along the northern (upstream) part of the river. Our flow-rate measurements showed that the river base-flow during 2000 and 2001 was 500 to 1100 L s(-1), which is about 40 times lower than the historical flow rates. Our measurements and calculations indicate that ground water input was 20 to 80% of the river water flow, and 20 to 50% of its solute mass flow. This study independently identifies the composition of possible end-members. These end-members contain high sulfate concentration and have similar chemical characteristics as were found in agricultural drains and in the "saline" Yarmouk River. Future regional development plans that include the river flow rate and chemistry should consider the interactions between the river and its shallow ground water system.

Dead Sea evaporation by eddy covariance measurements vs. aerodynamic, energy budget, Priestley–Taylor, and Penman estimates

“…600-700 × 10 6 m 3 a −1 ), meaning that the balance of the Dead Sea water budget is no longer sustained. The main water inflow to the Dead Sea is the Jordan River, but through anthropogenic interferences the discharge of the Jordan River into the Dead Sea decreased by 90 % down to 60-400×10 6 m 3 a −1 (Asmar and Ergenzinger, 2002;Holtzman et al, 2005) compared to its natural discharge before 1955. Further natural inflow by groundwater discharge and surface runoff is in the range of 235-243 × 10 6 m 3 a −1 (Siebert et al, 2014).…”

Observations of positive sea surface temperature trends in the steadily shrinking Dead Sea

“…This accelerating decrease in the Dead Sea wa-ter level cannot be explained by a steady decrease in water inflow to the Dead Sea from the River Jordan. After the construction of water supply projects in Israel (1964), Jordan (1966) and Syria (1970), the main flow of water into the River Jordan from the Sea of Galilee and from the Yarmouk River was blocked (Holtzman et al, 2005). Since that time, the only flow of fresh surface water into the River Jordan has included rare flood events and negligible contributions from small springs (Holtzman et al, 2005).…”

“…After the construction of water supply projects in Israel (1964), Jordan (1966) and Syria (1970), the main flow of water into the River Jordan from the Sea of Galilee and from the Yarmouk River was blocked (Holtzman et al, 2005). Since that time, the only flow of fresh surface water into the River Jordan has included rare flood events and negligible contributions from small springs (Holtzman et al, 2005). According to Gidon Bromberg (Yale Environment, #360, 2008, https://e360.yale.edu/features/will_the_jordan_ river_keep_on_flowing, last access: 10 November 2018), "massive water withdrawals for irrigation had created lush areas in the Jordan valley but have reduced the river to a trickle in many spots".…”

“…In order to analyze long-term changes in evaporation during the study period, we focused on the summer months when the observed decrease in the Dead Sea water level cannot be caused by precipitation. During the period of 2000-2001, Holtzman et al (2005 measured the Jordan River flow rate of approximately 0.5-1 m 3 s −1 . Therefore, even at the beginning of our study period, in every summer month, the water inflow from the Jordan River to the Dead Sea was approximately 1-2 × 10 6 m 3 .…”

Coupling groundwater modeling and biological indicators for identifying river/aquifer exchanges

“…Traditionally, in studies of groundwater/surface water interactions on the sector scale, hydraulic models have been ubiquitously used to locate areas of interactions with aquifers (e.g., the Murray River, Lamontagne et al 2002; the Snake River, Hortness and Vidmar Hortness and Vidmar 2004; the Jordan River, Holtzman et al Holtzman et al 2005 Urbano et al 2006). …”