The sampling network and program was designed to understand the dominating runoff generation mechanisms, the contributing groundwater reservoirs, and their temporal and spatial variability by combining hydrological, hydrochemical and environmental isotopic methods. According to LEIBUNDGUT (1984) the discharge dynamics as well as physical, hydrochemical and isotopic properties of a system are determined by its physiographic and geologic settings. Thus, any information about the system is enclosed in its discharge and is observed at the observation gauge. To decode this information tracerhydrological and traditional methods have to be applied. The resulting information will then represent area- and time-integrated properties of the particular catchment.
Main objective of this work is to determine the influence of global climate change on water resources in the Upper Jordan River catchment. Consequently, the four major sampling stations were predefined to be located at the major headwaters of the Jordan River, near existing gauges. An additional station was installed at the Sion stream, since this is an intermittent rivulet predominantly fed by rain and snowmelt in a karstic catchment located in the upper regions of the Israeli Hermon Mountains. Moreover, a gauging station of the HSI at this location enabled for recording of a continuous stream hydrograph, a precondition for the intended analysis. The sampling network is detailed in Table 6 and shown in Figure 8. Most stations were equipped with programmable liquid samplers (ISCO Inc., Lincoln, NE), the sampling interval was adjusted according to the discharge behavior. Sampling was intensified during rising discharge and peak flow and reduced during recession flow. Additionally, electrical conductivity and temperature were monitored continuously in intervals from 1 hour to 10 minutes. For storm events, samples were analyzed for a variety of parameters including 18O, 2H, major anions, major cations, SiO
2, DOC and TSS. The monitoring of stable isotopes and major anions/cations was pursued also during low flow conditions, however only weekly to monthly timesteps were retained.
Table 6: Streamflow sampling network in the UJRC and sampling frequency. Coordinates are given according to the New Israeli Grid. Station numbers are according to the Hydrological Service of Israel (HSI).
Sub catchment
Easting Northing Station (HSI)
Sampling Period Interval
km km
Dan 260.80 794.55 30131 ISCO sampler,
EC, T 11/02-05/04 up to 1 hour Hermon 260.25 791.31 30128 ISCO sampler,
EC, T
11/02-05/04 up to 1 hour Senir 257.70 792.20 30122 ISCO sampler,
EC, T
11/02-05/04 up to 1 hour Orevim 260.12 783.75 30155 ISCO sampler,
EC, T
11/03-04/04 up to 1 hour SionE 263.16 795.12 30118 manually 12/02-06/03 up to 1 day
ISCO sampler 12/03-04/04 up to 1 hour Sa’arE 266.00 793.83 30124 manually 12/02-04/04 weekly
GuvtahE 264.89 795.00 - manually 11/02-03/04 weekly NuheileE 259.50 797.73 - manually 11/02-06/04 weekly E = runoff event based
EC: continuous registration of electrical conductivity, T: continuous registration of temperature.
The necessary hydrometric measurements were provided by the Hydrological Service of Israel (HSI) that is operating stage recorders at the major tributaries in the area (see Figure 8).
Rain amounts and rain composition are one of the predefined end-members for the intended tracer-based hydrograph separation; they are known to be subject to a high spatial and temporal variability in mesoscale (= 10-1 to 10³ km²) catchments. Thus, the rain-sampling network required to be designed in a way that a representative input function was received for the particular period under consideration. Still the sampling network needed to be a compromise between the call for representative sampling (exhaustive) and the call for feasibility (point sampling).
To receive an input function that sufficiently describes spatial heterogeneity of precipitation within the UJRC, at least one sampler at a time representative for each of the investigated subcatchments was installed. Additional rain samplers were set up along altitude gradients to account for isotopic and chemical properties of rains. The precipitation sampling network is
detailed in Table 7 and shown in Figure 17. Rain samplers were constructed in a way that evaporative effects on rain samples were minimized, yet the intrusion of dust especially into the bulk samplers could not be prevented. However, these effects were much smaller for daily samples.
Table 7: Rainfall sampler locations in the UJRC and sampling intervals, (W: weekly, D: daily). Coordinates are given according to the New Israeli Grid.
Location Altitude Easting Northing Sub catchment Sampling Period
m a.s.l. km km
Moshav Shear Yeshuv 100 261.00 793.10 Dan/Hermon W/D 2002-04 Kibutz Mayan Barukh 200 256.99 793.97 Senir W/D 2002-04 Tel Dan Nature Reserve 227 260.94 794.57 Dan W/D 2002-04 Banias Nature Reserve 360 265.09 794.74 Hermon W/D 2002-04 Nimrod Nature Reserve 700 267.50 796.30 Hermon W/D 2002-04 Moshav Neve Ativ 1000 270.50 796.50 Hermon W 2002-04 Kibutz Shamir 200 262.20 786.20 Orevim W 2002-04 Orevim – tap road 810 264.70 785.00 Orevim W 2003-04
The temporal variability during single rain events plays an important role in tracer-based hydrograph separation, especially if stream response is fast. Both, temporal variability during single rain events and quick stream response were observed in the considered sub catchments. Therefore, it was originally planned to install two additional sequential rain samplers, yet that turned out to be logistically impossible during the course of this project.
The spatial variability of snow’s chemical and isotopic composition was accounted for by frequent sampling of fresh fallen snow along several snow transects. Transects were chosen such, that altitude gradients in chemical and isotopic composition of snow could be determined. For other effects, such as due to the location of sample in drift or non-drift areas could not be accounted for. Isotopic homogenization of snow packs and progressive enrichment of 18O in snowmelt are known phenomena (STICHLER, 1987, TAYLOR et al.,
2001). To study the former, a snow pit was dug and different snow layers were sampled twice during the season 2003/04. The temporal development of snowmelt, especially information such as the beginning of snowmelt, snowmelt amounts over time or the isotopic enrichment of snowmelt are generally important input functions for the separation of snowmelt from the
stream hydrograph. Yet, this exceeded the scope of this project and has to be addressed in succeeding projects for example by the installation of snowmelt lysimeters in representative areas.
The design of the groundwater sampling program was based upon earlier works by GILAD
and BONNE (1990), DAFNY et al. (2003) and GUR et al. (2003) and was intended to shed
further light on the hydrogeological characteristics of the predominant groundwater source areas. Springs were selected according to their discharge behavior, as well as their bulk hydro- and physico-chemical characteristics. Thus sampling focused on the major headsprings of the Upper Jordan River as well as the ‘Side springs’ emerging in the Golan Heights which are also significantly contributing to the Upper Jordan River. While springs were sampled at least on a seasonal basis (see Table 8), four of the springs were sampled on a monthly basis. During high flow conditions, sampling was intensified to weekly or even daily sampling. Due to logistic reasons, sampling was interrupted for three months during summer 2003.
Table 8: Locations of groundwater sampling and sampling program. Coordinates are given according to the New Israeli Grid. N is the number of samples taken.
Spring Altitude Easting Northing Station Sampling Period n
m a.s.l. km km (HSI)
Hermon springs
Dan 180 260.95 794.92 - monthly** 10/02-07/04 66
Leshem 180 261.10 794.90 - monthly** 10/02-07/04 67 Banias 390 265.20 794.90 30250 monthly** 10/02-08/04 60 Kezinim (Ain Hilu) 340 264.50 794.70 - monthly** 11/02-07/04 46
Sion 800 268.00 800.10 - snowmelt 13/03/04 3 Barid 243 260.95 796.25 30308 seasonal 02/03-07/04 5 Golan springs Hamroniya 210 262.40 787.00 30439 seasonal* 10/02-07/04 17 Dufeila 300 263.20 784.50 30474 seasonal* 10/02-07/04 18 Gonen 155 261.02 779.52 30515 seasonal* 10/02-07/04 14 Divsha 170 260.90 777.32 30535 seasonal* 10/02-07/04 14 Notera 90 260.60 772.20 30538 seasonal* 10/02-05/04 18 Jalabina 90 260.50 772.10 30568 seasonal* 10/02-07/04 14 Bet HaMekhes 110 259.40 768.60 30575 seasonal* 10/02-07/04 14 Elmin Jedida 170 260.20 766.70 30580 seasonal* 10/02-07/04 14
*up to monthly ** up to weekly
Since most of the springs are part of nature reserves or protected areas, permission for sampling was granted by the Society for the Protection of Nature in Israel (SPNI). Springs were monitored in situ for temperature and electrical conductivity; pH and alkalinity were determined in the lab on the day of sampling. All samples were analyzed for 18O, 2H, major anions and cations. Additional parameters determined were SiO2 and DOC. To receive further information about the distribution of mean residence times in the groundwater source areas, the majority of springs was sampled on reference dates in autumn 2003 and 2004 for tritium analysis. During this season, baseflow dominates the hydrograph. Another reference date sampling for 13C- and 14C-analysis was conducted in July 2004. In addition, a selection of samples was analyzed for major elements by inductively coupled plasma mass spectrometry (ICP-MS).
All the necessary hydrometric measurements were provided by the Hydrological Service of Israel (HSI) which is operating stage recorders at the major tributaries in the area (see Figure 8) and which is regularly conducting flow measurements at the majority of springs in the region.
Meteorological parameters such as radiation, temperature, relative humidity, and precipitation were downloaded from the Mop Zafon website (http://www.mop-zafon.org.il/ csv/index.html, in Hebrew), an organization which operates a meteorological network in the Upper Galilee region for agricultural purposes. Sequential rainfall data were provided by the Crop Ecology research group (Moshe Meron, Joseph Tsipris) of the MIGAL Galilee Technology Center, Israel, which is also part of the Mop Zafon network. Data on wind speed and direction in northern Israel were extracted from the database on air quality of the Israeli ministry of environment (see http://avir.sviva.gov.il/DocGenerator.asp, in Hebrew). Weather and snow forecasts were retrieved from http://www.israelweather.co.il website (in Hebrew and English).
Unfortunately, there is currently no fully equipped weather station on Mt. Hermon itself, leading to uncertainties considering the climatic conditions on high altitudes.