Miocene to sub-Recent magmatism at the intersection between the Dead Sea Transform and the Ash Shaam volcanic field: evidence from the Yarmouk River gorge and vicinity

The Yarmouk River gorge extends along the Israel–Jordan–Syria border junction. It marks the southern bound of the Irbid–Azraq rift and Harrat Ash Shaam volcanic field at their intersection with the younger Dead Sea Transform plate boundary. During the last ∼13 Ma, the gorge has repeatedly accumulated basaltic units, chronologically named the Lower, Cover, Yarmouk and Raqqad Basalt formations. We examined their origin and distribution through aerial photos, and geological and geophysical evidence. Our results define a southern Golan magmatic province, which includes exposed Miocene (∼13 Ma) basalts, gabbro–diabase intrusions below the gorge and the adjacent Dead Sea Transform valley, and numerous Pliocene–Pleistocene volcanic sources along the gorge. Cover Basalt (∼5.0–4.3 Ma) eruptions formed two adjacent 0–100 m thick plateaus on the transform shoulder before flowing downslope to fill the topographically lower Dead Sea Transform valley with ∼700 m thick basalts. Later incision of the Yarmouk River and displacement along its associated fault divided the plateaus and formed the gorge. The younger Yarmouk (0.8–0.6 Ma) and Raqqad (0.2–0.1 Ma) basalts erupted in the upper part of the gorge from volcanos reported here, and flowed downstream toward the Dead Sea Transform valley. Consequently, eruptions from six phreatic volcanic vents altered the Yarmouk River morphology from sinuous to meandering. Our results associate the ∼13 Ma long southern Golan volcanism with the proposed SW-trending extensional Yarmouk Fault, located east of the Dead Sea Transform. Hence, the Yarmouk volcanism is associated with the ongoing Harrat Ash Shaam activity, which is not directly linked to the displacement along the Dead Sea Transform.

Water Accounting Plus (WA+) through Remote Sensing in the Yarmouk Tributary Basin

<p>Coping with the issue of water scarcity and growing competition for water among different sectors requires effective water management strategies and decision processes. ‘Getting it right’ becomes doubly important when dealing with intenational transboundary rivers. The Yarmouk tributary to the Jordan River is one highly exploited in the Middle East, and is enveloped by ambiguous treaties and decades of violent and non-violent conflict. Seeking to chart a more sustainable and equitable future, this work performs a 'water accounting plus' methodology employing readily available remotely sensed satellite-based data coupled with available measurements.  A variety of methods described herein were used to detect irrigated crops and produce maps showing the distribution throughout the basin. The framework also focuses on the classification of land use categories and the processes by which water is depleted over all land use classes that contributes to separate the beneficial from non-beneficial usage of water. The analysis was started prior to the 2011 start of the Syrian war in order to study the initial distribution of land use classes as well as the water depletion processes before any change in the basin. It shows that more than half of the exploitable water is not consumed within the basin and depleted outside. In contrast, most of the water consumed within the basin is wasted and depleted in a non-beneficial way. Roughly 35% of the cultivated area shown to be irrigated through withdrawals which exceed the capacity of the source. This result reflects the high abstraction rates from groundwater via a large number of unlicensed wells mostly located at the Syrian side. This study also detect a deficiency in the water balance of the Yarmouk River. The findings are relevant to sustainable management not only for water-dependent sectors but also for geopolitical stability among the riparian countries. In this way, open- access remote sensing derived data can provide useful information about the status of water resources especially when ground measurements are poor or absent.</p><p> </p><p>Keywords: Yarmouk, Water Accounting Plus, IWM, Irrigated crops, WAPOR.</p>

Measurement of Radon (222Rn) Concentrations in the Basaltic Rocks of Yarmouk River, Jordan

This article was conducted to measure radon concentration levels in the Yarmouk River Basalt (YRB), North-Jordan. The YRB is of Quaternary in age and occurred as a successive sheet with a total thickness of 122 meters. The Yarmouk River Basalt is classified into four major phases. Namely, Yarmouk Sheet basalt, Yarmouk blocky basalt, Yarmouk massive basalt, and Yarmouk exfoliated. Furthermore, each major phase is subdivided into several flows. Sixteen samples are measured by using Nuclear Track Detector (Columbia Resin CR-39) in the laboratory. The results show that the concentration of radon is gradually decreased from the lower basalt first phase towards the upper fourth phase in considerable amounts. The values range from 12413.12 to 4137.71 Bq/m3, with an average value of 6635.74 Bq/m3. The results of this investigation indicate that the uranium isotopes element decay is the origin of radon emitted from the interstitial glass in the basalt rocks, rather than 222Rn emission along with fractures or major faults.

Assessment of the SWAT model in simulating watersheds in arid regions: Case study of the Yarmouk River Basin (Jordan)

The Soil and Water Assessment Tool (SWAT) was used to simulate monthly runoff in the Yarmouk River Basin (YRB). The objectives were to assess the performance of this model in simulating the hydrological responses in arid watersheds then utilized to study the impact of YRB agricultural development project on transport of sediments in the YRB. Nine and three years of input data, namely from 2005 to 2013, were used to calibrate the model, whereas data from 2014 to 2015 were used for model validation. Time series plots as well as statistical measures, including the coefficient of determination (R 2) and the Nash–Sutcliffe coefficient of efficiency (NSE) that range between 0 to 1 and −∞ to 1, respectively, between observed and simulated monthly runoff values were used to verify the SWAT simulation capability for the YRB. The SWAT model satisfactorily predicted mean monthly runoff values in the calibration and validation periods, as indicated by R 2 = 0.95 and NSE = 0.96 and R 2 = 0.91 and NSE = 0.63, respectively. The study confirmed the positive impact of soil conservation measures implemented in the YRB development project and confirmed that contouring can reduce soil loss from 15 to 44% during the study period. This study showed that the SWAT model was capable of simulating hydrologic components in the drylands of Jordan.

Hydrochemical evaluation of water resources and human impacts on an urban karst system, Jordan

Urban karst aquifers are threatened by anthropogenic activities, especially in semiarid developing countries. Recent water-sampling campaigns assessed the extent of groundwater-quality impairment in the Wadi Shueib in Jordan by a comprehensive hydrogeological and hydrochemical characterization of groundwater, wastewater, and imported water with its endmembers Lake Tiberias, Yarmouk River and Mukheiba wellfield. The results of a ternary mixing model with the mass ratios of Cl−/Br− and Ca2+/Mg2+ indicate that Lake Tiberias and Yarmouk River provide most of the imported water at the time of sampling in 2017 and Mukheiba wellfield provided minor amounts. The similarity in seasonal variations of Br− concentrations in the springs and the imported water revealed that imported water has generally a greater impact on groundwater than wastewater. However, the Br− concentrations also showed that the spatial wastewater impact is more visible towards urbanized areas due to increased infiltration of pollutants. The analysis of historical data series demonstrated the long-term urban impact on groundwater by an electrical conductivity increase over several decades, particularly since the mid-1990s, which is related to a doubling of Jordan’s population since that time and the associated urban growth. In this context, increased chloride and sulfate concentrations are noticeable due to the increased impact of more highly mineralized imported water and wastewater and decreasing recharge of low-mineralized rainwater. This study showed the hydrochemical differences in the Wadi Shueib groundwater system and serves as an example for the spatial and long-term response of karst aquifers to anthropogenic, seasonally variable input of imported water and wastewater.

The hydrogeology of the transboundary Yarmouk Gorge: a case study

<p>The Lower Yarmouk Gorge (LYG) marks both hydrogeological and Geopolitical triple junction. It serves as a meeting point for groundwater flowing from the Syrian Haurn Plateau, the Jordanian Ajloun Mountain and the Israeli Golan Heights. It is also the natural outlet of the 6,833 km<sup>2</sup> transboundary Yarmouk drainage basin, which was one of the main tributaries of the Jordan River. Within the gorge, springs and boreholes exhibits various water types flowing in a wide range of temperatures. For the three riparian states, the uncertainty of groundwater origin and flow paths imposes difficulties on the management of water flowing towards the Gorge. In last few years a series of studies have attempted to unveil some of the mystery. Numerical representation of rainfall field is a method developed in order to cope with the lack of data and contributed to the assessment of water consumption and aquifer discharge at the ungauged/unreported upstream parts of the basin (Shentsis et al., 2018 and 2019). Hydrochemistry of groundwater has been investigated in light of the natural processes in the larger Yarmouk Basin and a methodology was devalued for identifying different groundwater bodies in multi-aquifer systems (Möller et al., 2016; Rosenthal et al., 2020). Finally, a new structural model for the transboundary Lower Yarmouk Gorge has been suggested based on data from Israel and Jordan (Inbar et al., 2019) and several numerical simulations have been conducted for the study of this enigmatic fractured hydrothermal system (Magri et al., 2015 and 2016; Gurezki et al., 2016). Finally, it seems that currently we are a few steps closer towards a better understanding of this complex transboundary system and the lessons learned here can be used in other transboundary system around the world.</p><p>Inbar, N., E. Rosenthal, F. Magri, M. Alraggad, P. Möller, A. Flexer, J. Guttman, and C. Siebert (2019), Faulting patterns in the Lower Yarmouk Gorge potentially influence groundwater flow paths</p><p>Magri, F., N. Inbar, C. Siebert, E. Rosenthal, J. Guttman, and P. Möller (2015), Transient simulations of large-scale hydrogeological processes causing temperature and salinity anomalies in the Tiberias Basin</p><p>Magri, F., S. Möller, N. Inbar, P. Möller, M. Raggad, T. Rödiger, E. Rosenthal, and C. Siebert (2016), 2D and 3D coexisting modes of thermal convection in fractured hydrothermal systems - Implications for transboundary flow in the Lower Yarmouk Gorge</p><p>Möller, P., E. Rosenthal, N. Inbar, and F. Magri (2016), Hydrochemical considerations for identifying water from basaltic aquifers: The Israeli experience</p><p>Rosenthal, E., P. Möller, I. Shentsis, C. Siebert, F. Magri, J. Guttman, and N. Inbar (2020), Natural Processes determining the hydrochemistry of the groundwater in the Yarmouk basin</p><p>Shentsis, I., N. Inbar, E. Rosenthal, and F. Magri (2018), Numerical representation of rainfall field in basins of the Upper Jordan River and of the Yarmouk River</p><p>Shentsis, I., N. Inbar, E. Rosenthal, and F. Magri (2019), Assessing water consumption and aquifer discharge through springs based on the joint use of rain and flow data in the Yarmouk River Basin</p>