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The Tanour spring is one of the several karst springs located in the northern part of Jordan. Water samples from the Tanour spring and precipitation were collected in the area of Ajloun in NW Jordan for the analysis of stable oxygen and hydrogen isotopes to evaluate the spring response to precipitation events. Rainwater and snow samples were collected from different elevations during winters of 2013-2014 and 2014-2015. In addition, spring samples were collected between December 2014 and March 2015. δ(18)O values in rainwater vary from -3.26 to -17.34 ‰ (average: -7.84 ± 3.23 ‰), while δ(2)H values range between -4.4 and -110.4 ‰ (average: -35.7 ± 25.0 ‰). Deuterium excess ranges from 17.8 to 34.1 ‰ (average: 27.1 ± 4.0 ‰). The Local Meteoric Water Line for the study area was calculated to be δ(2)H = 7.66*δ(18)O + 24.43 (R(2) = 0.98). Pre-event spring discharge showed variation in δ(18)O (range -6.29 to -7.17 ‰; average -6.58 ± 0.19 ‰) and δ(2)H values (range -28.8 to -32.7 ‰; average: -30.5 ± 1.0 ‰). In contrast, δ(18)O and δ(2)H rapidly changed to more negative values during rainfall and snowmelt events and persisted for several days before returning to background values. Spring water temperature, spring discharge, and turbidity followed the trend in isotopic composition during and after the precipitation events. The rapid change in the isotopic composition, spring discharge, water temperature, and turbidity in response to recharge events is related to fast water travel times and low storage capacity in the conduit system of the karst aquifer. Based on the changes in the isotopic composition of spring water after the precipitation events, the water travel time in the aquifer is in the order of 5-11 days.

Groundwater is the main source of drinking water supply in Jordan. Over the past 30 years, many wellfields have been drilled and expanded to cover increasing drinking water demand caused by natural population growth, development of life standards and as a result of the influx of refugees to Jordan. In particular, northern Jordan groundwater resources have been severely depleted. Therefore, water suppliers and utilities have been increasingly challenged to meet water demand and deliver water of adequate quality and quantity to households in a timely manner. Meeting these objectives requires good data management, proper maintenance of groundwater wells, and effective wellfield management plans. We developed a novel monitoring strategy that allows the collection of relevant data for wellfield managers (e.g., yield, static and dynamic water level, as well as energy consumption). The new monitoring system, implemented in 2017, has greatly enhanced data availability in comparison to the situation between 2012 and 2016. The data are used in an operational decision support tool based on simple interpretation of the field observations. The implementation of the project was done using both bottom-up and top-down approaches for the Wadi Al Arab wellfield. Our results evidence that (i) simple strategies can lead to a significant improvement of wellfield management, reducing the maintenance time of the wells though appropriate monitoring (from an average of four days/maintenance/well in 2012 to less than one day/maintenance/well in 2017); (ii) the joint combination of bottom-up and top-down approaches leads to an effective implementation of the monitoring system; (iii) the simplicity of the proposed monitoring strategy makes it suitable for further implementation in other wellfields in Jordan and countries in a similar situation of both data and water scarcity.

In 2017, a comprehensive review of groundwater resources in Jordan was carried out for the first time since 1995. The change in groundwater levels between 1995 and 2017 was found to be dramatic: large declines have been recorded all over the country, reaching more than 100 m in some areas. The most affected areas are those with large-scale groundwater-irrigated agriculture, but areas that are only used for public water supply are also affected. The decrease of groundwater levels and saturated thickness poses a growing threat for drinking water supply and the demand has to be met from increasingly deeper and more remote sources, causing higher costs for drilling and extraction. Groundwater-level contour lines show that groundwater flow direction has completely reversed in some parts of the main aquifer. Consequently, previously established conceptual models, such as the concept of 12 “groundwater basins” often used in Jordan should be revised or replaced. Additionally, hydraulic conditions are changing from confined to unconfined; this is most likely a major driver for geogenic pollution with heavy metals through leakage from the overlying bituminous aquitard. Three exemplary case studies are presented to illustrate and discuss the main causes for the decline of the water tables (agriculture and population growth) and to show how the results of this assessment can be used on a regional scale.

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