Yarmouk River Basin Research Articles

Calculation and Management of Water Supply and Demand under Land Use/Cover Changes in the Yarmouk River Basin Governorates in Jordan

This paper presents the calculation and management of water supply and demand under land use/cover changes in the Yarmouk River Basin in Jordan for the years 1997, 2007 and 2017. It aims to analyze and link the changes in the land classes with the water resources supply demand as the groundwater is unable to meet the inhabitants demand, necessitating land management practices. The method includes deriving land use/cover maps using the supervised classification, identifying basin governorates, cities and villages, calculating the basin governorates’ inhabitants, water demand, supply of internal wells, water loss, and actual water consumption. The results showed an increase in the urban area by 3.01%, while forests, rain-fed vegetables and crops declined by 1.57% and 1.09%, respectively. Urbanization appears mainly at the expense of rangelands, an important change affecting water supply from internal wells due to increased pumping to balance population demand. Although it is decreasing per capita, the water demand is high. Changing land use practices, securing inter-basin water resources, and calculating water losses is a challenge of great importance that can manage water shortages and increase actual consumption. This research is important in order to understand the supply demand situation and to aid a wide range of users, water-managers, land-planners and decision-makers.

Influence of Population Growth on Supply, Demand, and Quality Issues of Water Resources in the Yarmouk River Basin in Jordan

This study was carried out to investigate the influence of population growth on supply, demand, and quality issues of water resources in the Yarmouk River Basin in Jordan for twenty years. The population growth data for the years 1997 and 2017 was derived from four Jordan governorates, i.e., Mafraq, Irbid, Jerash, and Ajloun, as well as for the population of the Yarmouk Basin was calculated, where a part of the population of these governorates resides within Basin. The water supply and the number of wells were also determined during this study. Various physicochemical parameters of water, like pH, EC, TDS, DO, NO2, and NO3, were also evaluated. Water supply, demand, and quality issues were also identified in collaboration with relevant stakeholders. The study showed an increase in the Kingdom's population in four governorates from about 1.27 to 2.88 million inhabitants, while the population of four governorates in the Yarmouk Basin increased from about 639,992 to 1.53 million inhabitants, and it is more than doubling. Comparing the population with the water supply, the numbers of wells and their uses showed significant changes, as evidenced by the substantial increase in the water supply. The studied physiochemical parameters were within the permissible limits of the National Standards. The critical water issues reported in the study area are difficulties in law enforcement and rapid population growth, which interactively affect the water supply. The study's findings will assist decision-makers in managing future water supplies as they face challenges in securing additional water, and there is an urgent need for research and future scenarios to meet water needs.

Exploring Different Approaches for Computing the Standardized Precipitation Index to Characterize Dry and Wet Periods in the Yarmouk River Basin, Jordan

Exploring Different Approaches for Computing the Standardized Precipitation Index to Characterize Dry and Wet Periods in the Yarmouk River Basin, Jordan

Scenario simulation and analysis in the transboundary Yarmouk River basin using a WEAP model

ABSTRACT Water is a finite resource but an essential one. The continuously increasing demand leads to competition and conflict over limited resources. Syria, Jordan, and Israel compete over the water resources in the transboundary Yarmouk River basin where two water agreements dictate the allocation of water. The two arrangements are far from being efficient and fair while little cooperation is being made over sharing the resources that are being over-exploited. In this study, water sustainability was investigated under projected developments and trends based on the current use and allocation regime in the watershed using several scenarios. A one bucket soil moisture model was adopted and optimized in order to fully represent the ever-changing hydrology of the basin using the Water Evaluation and Planning (WEAP) tool. Demands along with the existing water infrastructure and their operation were modelled despite the lack of many data and the huge uncertainty in some. Simulation of business as usual scenario showed that continuing with the current use cannot be sustainable in the short and long term. The growth of both agriculture and population produced huge water shortages in all demand sectors. Under climate change scenarios RCP 4.5 and RCP 8.5, surface water availability and the retention of dams reduced significantly. The share of Jordan from the Yarmouk River was the most vulnerable to climate change impacts. Enhancing irrigation efficiency and a more stable population growth based on the UN medium variant population projection showed improvements in water coverage within all demand sectors. Analysis of future scenarios suggests that water shortage is expected in all riparian states of the basin but can be mitigated by reducing demands.

A Remote Sensing-Based Analysis of the Impact of Syrian Crisis on Agricultural Land Abandonment in Yarmouk River Basin.

In this study, we implemented a remote sensing-based approach for monitoring abandoned agricultural land in the Yarmouk River Basin (YRB) in Southern Syria and Northern Jordan during the Syrian crisis. A time series analysis for the Normalized Difference Vegetation Index (NDVI) and Normalized Difference Moisture Index (NDMI) was conducted using 1650 multi-temporal images from Landsat-5 and Landsat-8 between 1986 and 2021. We analyzed the agricultural phenological profiles and investigated the impact of the Syrian crisis on agricultural activities in YRB. The analysis was performed using JavaScript commands in Google Earth Engine. The results confirmed the impact of the Syrian crisis on agricultural land use. The phenological characteristics of NDVI and NDMI during the crisis (2013–2021) were compared to the phenological profiles for the period before the crisis (1986–2010). The NDVI and NDMI profiles had smooth, bell-shaped, and single beak NDVI and NDMI values during the period of crisis in comparison to those irregular phenological profiles for the period before the crisis or during the de-escalation/reconciliation period in the study area. The maximum average NDVI and NDMI values was found in March during the crisis, indicating the progress of natural vegetation and fallow land, while they fluctuated between March and April before the crisis or during the de-escalation/reconciliation period, indicating regular agricultural and cultivation practices.

Assessment of water resources in Yarmouk River Basin using geospatial technique during the period 1980–2020

Assessment of water resources in Yarmouk River Basin using geospatial technique during the period 1980–2020

Time Series Analysis of Rainfall Variability at North Jordan: A Case Study at Yarmouk River Basin

Water represents a key challenge to sustain the progress of Jordan. Providing healthy drinking water, along with current scarcity is one of the most major constraints in the water sector. This paper pursues to investigate the Spatio-temporal distribution of rainfall variability for time slice 1985-2014 over the Yarmouk River Basin (YRB) – Jordan side. Ten rainfall gauges were selected within the basin over the observation period. Applying two nonparametric statistical tests; Mann-Kendall to detect the rainfall trend in YRB, and Kolmogorov–Smirnov to detect the variations of rainfall distribution. Besides, the GIS spatial analyst tool was utilised to create interpolated rainfall map using the Thiessen polygons method. The results indicated that YRB will witness a potential decline in annual rainfall in most stations. Further, a shift in rainy season timing 2 and 58 days was observed at late in the start of the season (SoS) and 2 to 48 days for an early end of the season (EoS) on a decade’s basis accompanied by the significant uptrend in the long-term.

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

Abstract 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.

Climate change vulnerability assessment for selected agricultural responses at Yarmouk River Basin Area, Jordan

Although climate change impacts on the agricultural sector were investigated intensively, however, vulnerability assessments and adaptation planning at the community level are still limited. This study aimed at providing a comprehensive climate change vulnerability assessment of four agriculture responses of barley production, wheat production, olive trees production, and goats’ mortality at the Yarmouk River Basin in northern Jordan using a qualitative-quantitative scoring method based on actual estimations of exposure, sensitivity, and adaptive capacity with an emphasis on community engagement. Thirty-year temporal variability (1982–2012) analysis using Kendall test and Pearson correlation test for three climatic variables (maximum and minimum air temperature, and annual rainfall) indicates high significant exposure level of increasing air temperature trends by rates of 0.07 °C/year and 0.06 °C/year for maximum and minimum temperature, respectively, and insignificant annual rainfall reductions ranging spatially from 2.1 mm/year at Irbid governorate to 2.9 mm/year at Mafraq Governorate. Agriculture responses sensitivity assessment indicates goats’ mortality followed by olive production are moderately correlated with climate variables (r ranges from 0.32 to 0.57). The adaptive capacity assessment highlights the presence of low to moderate financial, institutional, political enforcement, technology implementation, and awareness of the farmers to climate change impacts and potential adaptation measures that subjected the study area to be ranked as moderately to highly vulnerable to climate change impacts. Multi-criteria decision analysis suggests that irrigation water-related adaptation measures are listed within top priorities. This paper addresses the qualitative-quantitative vulnerability assessment approach at the local rural level and through participatory engagements to be effective for improving the vulnerable adaptive capacities and suggesting further recommendations to be mainstreamed urgently with governmental strategies and action plans.

Quantitative Assessment of Contested Water Uses and Management in the Conflict-Torn Yarmouk River Basin

AbstractThe Yarmouk River basin is shared between Syria, Jordan, and Israel. Since the 1960s, Yarmouk River flows have declined more than 85% despite the signature of bilateral agreements. Syria an...

Rainfall-Runoff modeling for Semi-arid and trans-boundary Yarmouk River Basin

The capability of the Soil and Water Assessment Tool (SWAT) to simulate streamflow for Yarmouk River Basin (YRB) is investigated. The YRB is a semi-arid and trans-boundary basin extends within two countries Jordan and Syria. The available daily precipitation, potential evapotranspiration and runoff data were used in conjunction with an optimization technique to calibrate SWAT a semi-distributed hydrological model. The basin was modeled at two conditions: (1) The basin as if it has stayed without any man made changes (pre-development) and (2) The basin as it gets changed in the life (post-development). The modeling evaluation measures indicated a satisfactory performance at the monthly scale under both conditions. For the pre-development condition, the model performed well for the YRB for which the coefficients of determination (R2) were 0.87 and 0.81 both calibration (1986-1995) and validation (1996-2000) periods, respectively. The average monthly runoff from the model compared well to the observed average runoff. The error of the observed and simulated streamflow is within acceptance limit. Similarly, the model performed well for post-development conditions with R2 of 0.89 and 0.81 for calibration and validation periods, respectively. The modeling results obtained in this study can be used by water authorities to enhance the water resources management of YRB. Moreover these results can be used to investigate the impact of climate change on the surface water resources of this basin.

Assessment of land use/land cover change and its environmental impacts using remote sensing and GIS techniques, Yarmouk River Basin, north Jordan

The land use/land cover (LULC) changes in Yarmouk River Basin (YRB) over a period of 22 years (1987–2009) have been analyzed, using remotely sensed data and geographic information system. Methods of LULC changes involved thematic change, image difference, and the normalized difference vegetation index (NDVI). Patch Analyst 5 for ArcGIS was used for the spatial analysis of landscape patches. The results revealed drastic changes in the LULC, with an overall change of more than 79%. Agricultural expansion has occurred at the expense of rangeland (16%) and forest (14%), whereas urban areas have taken over 2.65% of the agricultural areas, 2.11% of the forest, and 1.3% of the rangeland. The values of image difference were in agreement with the increase of urbanization and deforestation activities, besides the increased cultivation activities. The decrease in NDVI values indicates a degradation of vegetation cover. Class area (CA), mean patch size (MPS), and number of patches (NumP) for rangeland have decreased from 39,386 ha, 5.62 ha, and 7010 in 1987 to 17,729 ha, 4.62 ha, and 3838 in 2009, respectively. Similarly, CA, MPS, and NumP for forest land have decreased from 31,551 ha, 0.74 ha, and 42,548 in 1987 to 9558 ha, 0.65 ha, and 14,745 in 2009, respectively. Similar changes were shown to barelands. These results points to fragmentation of the natural land and habitat loss. On the other hand, CA and MPS of agriculture have increased from 35,306 ha and 0.72 ha in 1987 to 78,991 ha and 8 ha in 2009, respectively, indicating agricultural expansion. In addition, CA and NumP of urban have increased from 5513 ha and 89 in 1987 to 16,393 ha and 1536 ha in 2009. At the landscape level, the MPS has increased from ≈ 1 ha in 1987 to 3.7 ha in 2009, whereas NumP has decreased from 146,463 in 1987 to 38,006 in 2009, which means that the landscape became more clumped and continuous. The Shannon diversity index and Shannon evenness index have decreased, indicating that the landscape became more homogenous and more even over the 22 years of the study. It is believed that the major driver of LULC changes in the study area is urban growth, which usually leads to habitat disturbances.

Assessing water consumption and aquifer discharge through springs based on the joint use of rain and flow data in the Yarmouk River Basin

The method is proposed for assessing water consumption in the transboundary basin under the scarce available data on exploitation of water resources. The method is based on analysis of the dynamic rain–flow relationship which confirms the consistent flow decline during subsequent sub-periods as a result of the increased water consumption. The proposed method was applied to the Yarmouk River Basin up to the Maqaren Station. The study area (6058 km2) includes Syrian (more 80%) and Jordanian territories. The present study provided complete information on consumption from the Yarmouk River in Syria (1971–2009) and confirmed its significant impact on flow reaching Jordan (downstream area) and on aquifer discharge through springs. During 1997–2009 the total water consumption was estimated as 76% of the Yarmouk Natural Flow vs. 24% for the measured flow at Maqaren Station. Similar estimates for surface water and for groundwater are 82% and 67% vs. 18% and 23%, respectively. In 2006–2009, annual consumption (total, SW and GW) critically increased and reached to 95–100% of the Natural Flow. The perennial base flow of the Yarmouk River at Maqaren Station is caused by outflow of springs in the outlet section of the Hreer tributary, which represents the local aquifer discharge. Its mean annual value was assessed as 120 MCM (40% of the Yarmouk natural flow) but it decreased to almost complete dry-out in 2006–2009 under conditions of the decline in the water level of the basin aquifer and the depletion and drying of the springs as the result of the unrestrained increased pumping of groundwater. These results are useful for water balance estimation as well as for assessment and management of the water resources in Syria and Jordan. The method can be adapted to real-time monitoring of the water consumption from the Yarmouk River (Syria). The proposed method can be applied to other areas with problems of the transboundary water relations under scarce water resources and limited data on the water use.

Numerical representation of rainfall field in basins of the Upper Jordan River and of the Yarmouk River

A non-linear complex rain–elevation regression model is proposed for the numerical representation of rainfall field in an area with complex plain/mountainous topography, non-uniform distribution of rain gauge network and scarce data of observations. The model is applied to basins of the Upper Jordan River (of the Lake Kinneret) and of the Yarmouk River in which the major flow of the Jordan River is formed. The model is implemented in two steps: (1) study of the rainfall field, based on the average long-term (climatic) data, its description by the function of elevation and other factors, and optimization of model parameters (normalized coefficients of the Taylor series); and (2) estimation of rainfall in each historical year using the available data (less complete and irregular than climatic data) as well as a priori known parameters. The basic hypothesis is inter-annual stability of the model parameters. As a necessary primary stage, the Upper Jordan River (Lake Kinneret) Basin and the Yarmouk River Basin were divided, respectively, into seven and five regions, considering the specific regional relationships between the mean annual rain depth and elevation. It occurred that both basins are represented by a common system of rain–elevation curves as a single rain field where the mean annual rain increases with altitude and decreases from west to east and from north to south. For each region, the parameters of the model were optimized as a base for estimating the annual (month) rain (mean or yearly volume/depth) in each point of grid, in each basin (sub-basin) or in the whole watershed. The necessary condition is numerical presentation of the topography. Derived rain rates can serve as fundamental input data for numerical modeling of surface- and groundwater flow. This method can be applied to other areas at different temporal and spatial scales.

Whose ‘reality’? Discourses and hydropolitics along the Yarmouk River

ABSTRACTThis article investigates Jordanian and Syrian hydropolitical discourses around the bilateral relations along the Yarmouk River, with a focus on the decreased flow of the Yarmouk River reaching the Wahda Dam. The article examines the bilateral agreements, the hydropolitical discourses they generate, and the competing solutions they open. By situating the analysis in the broader Jordanian–Syrian relations and considerations of power asymmetries, the empirical case study of the Yarmouk River Basin contributes to both hydropolitics and environmental discourse theory literatures.

Artificial rainfall tests, soil moisture profiles and geoelectrical investigations for the estimation of recharge rates in a semi-arid area (Jordanian Yarmouk River Basin)

To overcome the limitations posed by the limited relevant data for recharge estimation in the Jordanian Yarmouk River basin, a mass balance methodology is developed which is simple and may be easily applied to other arid and semi-arid landscapes. This is done by integrating available climatic data with new rain–runoff relationship data, as measured using a specially designed and built artificial rainfall simulator, and changing soil moisture profiles through the hydrological year, as measured in the field. The amount of moisture in the soil after rainfall events changes as a result of both evaporation and of drainage into deeper levels (recharge). The soil moisture profiles at depth are evaluated using geophysical techniques that allow for the tracking of recharge fronts. After rainfall events, the distribution of its fate between runoff, evaporation and recharge is determined. Water in the soil beyond the field capacity can be demonstrated to mostly contribute to the ultimate groundwater recharge in the area. Water stored beyond the permanent wilting point is not considered to contribute significantly to the recharge regime. Because of the irregular nature of rainfall, the amount of recharge is found to be related to the spacing of wet and dry spells during the winter months more than the actual amount of rainfall. Prolonged dry periods allow for excess water to drain into the deeper soil and thus to the groundwater, and thus allow for more uptake following subsequent rainy events. Evaporation does not significantly contribute to the drying of the soils. Reanalysis of rainfall and evaporation data from previous years suggests that recharge rates range from 20 to 37 % of total rainfall amounts, as opposed to the currently assumed 5 %.

Multivariate statistical analysis and environmental isotopes of Amman/Wadi Sir (B2/A7) groundwater, Yarmouk River Basin, Jordan

AbstractMultivariate statistical techniques, cluster and factor analyses were applied on the Amman/Wadi Sir groundwater chemistry, Yarmouk River basin, north Jordan. The main objective was to investigate the main processes affecting the groundwater chemical quality and its evolution. The k‐means cluster analysis yields three groups with distinct ionic concentrations. Cluster 1 comprises the vast majority of the sampled wells, and the water that belongs to this cluster can be classified as freshwater. Cluster 2 comprises only 2% of the sampled wells; it has the highest ionic concentration. The water of this cluster can be classified as brackish water. Cluster 3 involves 23% of the sampled wells, and it has total ionic concentration intermediate to that of clusters 1 and 2. Factor analysis yields a three‐factor model, which explains 76.77% of the groundwater quality variation. Factor 1 ‘salinity factor’ involves EC, Na+, Cl‐, SO4‐2, K+ and Mg+2 and reflects groundwater salinization because of overpumping. Factor 2 ‘hardness factor’ includes Ca+2, HCO3‐ and the pH value and signifies soil–water/rock interaction. Factor 3 ‘nitrate factor’ involves only NO3‐ and points to groundwater contamination because of human activities, mainly untreated wastewater, and crops and animal cultivation in the unconfined portion of the aquifer. Factors 1 and 3 can be described as human‐induced factors, whereas factor 2 can be described as geogenic factor. Factors' scores were mapped to deduce the controlling processes on the groundwater chemistry. Stable isotope composition of 18O and 2H has revealed that the groundwater is a mixture of two water types. The radioactive isotopes tritium and 14 C were used to evaluate present day recharge to the aquifer and to estimate the groundwater age, respectively. Present day recharge to the groundwater is taking place in the unconfined portion of the aquifer as it is indicated by the measurable tritium content and low groundwater age. Copyright © 2012 John Wiley & Sons, Ltd.

Seasonal variations in water quality of Al-Wehda Dam north of Jordan and water suitability for irrigation in summer

Al-Wehda dam is an impoundment on the Yarmouk River basin north of Jordan, which came recently into operation. The reservoir is designated to provide water for agricultural, domestic, and industrial uses. Evaluation of seasonal trends in water quality of Al-Wehda dam over the year 2010 showed strong influences by weathering and leaching of geologic units along with discharge of effluents from the adjacent agricultural lands. Seasonal trends in TDS level showed slight variations, though its concentrations have been affected by events of rainfall and evaporation. The presence of total nitrogen (TN) and total phosphorus (TP) promoted the development of photosynthetic algae. Temporal fluctuations in TN, TP, chlorophyll a, COD, and BOD have been observed with peaks occurred in spring season. TN to TP ratios varied seasonally with a minimum ratio observed in spring concurrent with algal bloom. Eutrophication tends to occur throughout the year, though its intensity increased in springtime. A variety of water quality parameters has been used to evaluate water for irrigation use during summer time when the water demand for irrigation increased. Of all parameters evaluated, Na% and TH indicated that the reservoir water is not suitable for irrigation purposes.

Evaluation of aquifers vulnerability to contamination in the Yarmouk River basin, Jordan, based on DRASTIC method

The existing different human activities and planned land uses put the groundwater resources in Jordan at considerable risk. There are evidences suggesting that the quality of groundwater supplies in north Jordan is under threat from a wide variety of point and non-point sources including agricultural, domestic, and industrial. Vulnerability maps are designed to show areas of greatest potential for groundwater contamination on the basis of hydrogeological conditions and human impacts. DRASTIC method incorporates the major geological and hydrogeological factors that affect and control groundwater movement: depth to groundwater (D), net recharge (R), lithology of the aquifer (A), soil texture (S), topography (T), lithology of vadose zone (I), and hydraulic conductivity (C). The main goal of this study is to produce vulnerability maps of groundwater resources in the Yarmouk River basin by applying the DRASTIC method to determine areas where groundwater protection or monitoring is critical. ArcGIS 9.2 was used to create the groundwater vulnerability maps by overlaying the available hydrogeological data. The resulting vulnerability maps were then integrated with lineament and land use maps as additional parameters in the DRASTIC model to assess more accurately the potential risk of groundwater to pollution. The general DRASTIC index indicates that the potential for polluting groundwater is low in the whole basin, whereas the resulting pesticide DRASTIC vulnerability map indicates that about 31% of the basin is classified as having moderate vulnerability, which may be attributed to agricultural activities in the area. Although high nitrate concentrations were found in areas of moderate vulnerability, DRASTIC method did not depict accurately the nitrate distribution in the area.

The artesian thermal groundwaters of northern Jordan: insights into their recharge history and age

The scarcity of water resources in Jordan imposes strategic difficulties for economic development and has been a basis for disputes with neighbouring countries. A welcomed discovery in the past decade is the occurrence of artesian thermal groundwaters at Mukhebeh in the lower Yarmouk valley, which produce over 40 × 106 m3 year−1 of fresh water. The principal resources occur in the upper B2 Formation (Campanian), a limestone overlain by confining marls of the B3 Formation (Maastrichtian). Additional resources are found near by along the eastern Jordan Rift Valley (JRV), in the underlying A7 limestone (Turonian).Groundwaters in the Mukhebeh (B2) wells are low salinity (500 mg l−1 TDS) Ca(Mg)-HCO3 waters with elevated HS− attributed to sulphate reduction driven by oxidation of aquifer-derived organic matter. The JRV (A7) groundwaters are similar to the B2 waters with the exception of higher Mg2+ and HCO3− attributed to dolomite dissolution and sulphate reduction. Groundwaters from JRV 1 and the Maqla spring at Mukhebeh are NaCl waters with a strong Ca(Mg)-HCO3 facies (900 to 1000 mg 1−1 TDS). The elevated temperatures of all groundwaters (30 to 54°C) can be attributed to heating along a local geothermal gradient of 2.5°C per 100 m. Departures from this gradient are due to vertical flow in fault zones and possibly to the local influence of an intrusion (MK-7).All groundwaters are characterized by a late Holocene (modern) stable isotope signature. Groundwaters from the high yielding upper B2 aquifer (MK wells) have a δ18O/δ2H composition demonstrating recharge in the B2 outcrop region, near and to the east of Irbid, within the Yarmouk River basin. Conversely, the deeper A7 aquifer groundwaters (JRV wells) are recharged at a lower elevation in the rift valley margin, where incised wadis have exposed these strata. The deepest Al to A6 strata (Magla spring and JRV 1 well) contain the isotopically most depleted groundwaters. Based on comparison with precipitation and phreatic groundwaters, recharge in the highest landscape of northern Jordan is likely, although a source of recharge from the northern Golan region of Syria cannot be excluded.All thermal waters are essentially 3H-free. Estimates of their mean subsurface residence times have been constrained on the basis of 14C inDIC Significant corrections have been made for 14C-dilution processes including carbonate dissolution, sulphate reduction and a tertiary process involving either incorporation of mantle CO2 or matrix exchange. All dilution processes were quantified on the basis of geochemical and 13C mass balance equations. Modelled ages show that recharge for most B2 and A7 groundwaters occurred during the late Holocene (recent to 5 ka BP).