Discharge estimation of submarine springs in the Dead Sea based on velocity or density measurements in proximity to the water surface

Abstract

The Dead Sea is a closed lake, the water level of which is lowering at an alarming rate of about 1 m/year. Factors difficult to determine in its water balance are evaporation and groundwater inflow, some of which emanate as submarine groundwater discharge. A vertical buoyant jet generated by the difference in densities between the groundwater and the Dead Sea brine forms at submarine spring outlets. To characterize this flow field and to determine its volumetric discharge, a system was developed to measure the velocity and density of the ascending submarine groundwater across the center of the stream along several horizontal sections and equidistant depths while divers sampled the spring. This was also undertaken on an artificial submarine spring with a known discharge to determine the quality of the measurements and the accuracy of the method. The underwater widening of the flow is linear and independent of the volumetric spring discharge. The temperature of the Dead Sea brine at lower layers primarily determines the temperature of the surface of the upwelling, produced above the jet flow, as the origin of the main mass of water in the submarine jet flow is Dead Sea brine. Based on the measurements, a model is presented to evaluate the distribution of velocity and solute density in the flow field of an emanating buoyant jet. This model allows the calculation of the volumetric submarine discharge, merely requiring either the maximum flow velocity or the minimal density at a given depth.

A Vision on a UNESCO Global Geopark at the Southeastern Dead Sea in Jordan—How Natural Hazards May Offer Geotourism Opportunities

“…Underwater investigation: The submarine investigation will be conducted at the immediate conduit outlets in the shallow Dead Sea delta area for the first time. Several locations have been identified as prone to submarine groundwater discharge (SGD) in previous studies both on the western side of the lake [62,63] as well as in the measurement area (see aerial photos in partner paper I and [47]). The gain will be a better understanding of the system before-and after lake regression and the relation of SGD to the future collapse of the exposed ground.…”

“…Groundwater and surface water from wadis with catchments in the Eastern Rim Highlands bring fresh water into the fertile plains. There are several aquifers of tertiary age and superficial character (e.g., alluvial sediments of the Lisan marl) and outcropping of early cretaceous (Kurnub sandstone) and late-cretaceous/early Tertiary age (Ajlun Belqa carbonates, see geologic map in partner paper I), which may also release water un der the Dead Sea through submarine springs, as evidenced on the Western side of the lak [62,63]. New stream channels are forming inside the dynamic salt karst system (Figure 9a c), and springs often are related to sinkhole formation (Figure 9d-e) and canyon develop ment (Figure 9f), loaded by sediments and dissolved minerals (Figure 9g).…”

Investigation of the Spatio-Temporal Behaviour of Submarine Groundwater Discharge Using a Low-Cost Multi-Sensor-Platform

“…Hence, the density difference between discharged groundwater and the ambient seawater is small. This small difference results in a small upwelling momentum of the discharged seawater [27]. In addition, depth profiles in Figure 13 show a higher surface temperature resulting in a lower density layer at the surface.…”

“…The majority of the previously developed methods either investigate the behaviour of SGDs within the aquifer or the mixing of the discharged water on larger scales, for example mixing models applied for calculating SGD inflows into bays [6]. However, the distribution of the discharged water within the surrounding water column in the proximity of SGDs is not well investigated [7,27]. Methods used in these studies, for example thermal radiance cameras or current measurements, only allow limited spatial investigations of the area near SGDs.…”