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Tibor G.,GT Imaging Ltd. | Tibor G.,Israel Oceanographic And Limnological Research | Markel D.,Israel Water Authority | Kaplan D.,Israel Nature and Parks Authority | And 2 more authors.
Israel Journal of Plant Sciences | Year: 2012

Lake Kinneret is a major water source for the State of Israel, hence it is managed and preserved by the Israel Water Authority. Mapping the new vegetation growth along the exposed shores of Lake Kinneret during periods of retreating lake water levels is of great importance in the management of the lake and its water quality. When the lake level rises this vegetation is covered by water, decays, and releases nutrients into the lake, possibly enhancing algal blooms. In December, 2001, when the lake level was -214.72 m, a rapid and cost-effective vegetation mapping was done along the retreating shoreline using a GeoSky™ system that integrates oblique airborne video synchronized with Differential Global Positioning System (DGPS) and an electronic compass, and displays them within a Geographic Information System (GIS). Six major vegetation classes with twelve subclasses were interpreted from the video along the newly exposed shoreline between -209 m (highest lake level) and -214.72 m, their borders mapped, and a total vegetation area of 73.6 km2 was calculated. Dominant plant species, their features and structure were described. The coverage area of each vegetation class was mapped using the -ArcView 3X (from ESRI) GIS tools within GeoSky™, finding Phragmites australis, Tamarix sp., and Cyperus spp. as representatives of the major vegetation classes. The biomass of each major class was then calculated from the coverage area according to dry matter concentration of 2.5, 1.5, 1, and 0.5 kg/m2 of Phragmites, Tamarix, Cyperus, and other, respectively. Total phosphorus (P) and total nitrogen (N) were calculated utilizing concentrations of 0.2% of total P and 1.2% of total N in the dry biomass of vegetation. Maximum cumulative inventories were evaluated to 23,500 kg of phosphorus and 141,000 kg of nitrogen. It was then recommended to the Water Authority of Israel to leave the shoreline vegetation untouched instead of cleaning it with a mower. © 2012 Science From Israel / LPPltd., Jerusalem.

Wu W.,U.S. National Center for Atmospheric Research | Liu Y.,U.S. National Center for Atmospheric Research | Ge M.,U.S. National Center for Atmospheric Research | Rostkier-Edelstein D.,Israel Institute of Biology Research | And 7 more authors.
Atmospheric Research | Year: 2012

Most of the annual rainfall in the Southeastern Mediterranean falls in the wet season from November to March. It is associated with Mediterranean cyclones, and is sensitive to climate variability. Predicting the wet season precipitation with a few months advance is highly valuable for water resource planning and climate-associated risk management in this semi-arid region. The regional water resource managements and climate-sensitive economic activities have relied on seasonal forecasts from global climate prediction centers. However due to their coarse resolutions, global seasonal forecasts lack regional and local scale information required by regional and local water resource managements. In this study, an analog statistical-downscaling algorithm, k-nearest neighbors (KNN), was introduced to bridge the gap between the coarse forecasts from global models and the needed fine-scale information for the Southeastern Mediterranean. The algorithm, driven by the NCEP Climate Forecast System (CFS) operational forecast and the NCEP/DOE reanalysis, provides monthly precipitations at 2-4. months of lead-time at 18 stations within the major regional hydrological basins. Large-scale predictors for KNN were objectively determined by the correlations between the station historic daily precipitation and variables in reanalysis and CFS reforecast. Besides a single deterministic forecast, this study constructed sixty ensemble members for probabilistic estimates. The KNN algorithm demonstrated its robustness when validated with NCEP/DOE reanalysis from 1981 to 2009 as hindcasts before applied to downscale CFS forecasts. The downscaled predictions show fine-scale information, such as station-to-station variability. The verification against observations shows improved skills of this downscaling utility relative to the CFS model. The KNN-based downscaling system has been in operation for the Israel Water Authority predicting precipitation and driving hydrologic models estimating river flow and aquifer charge for water supply. © 2012.

Tenne A.,Israel Water Authority | Hoffman D.,ADAN Technical and Economic Services Ltd. | Levi E.,ADAN Technical and Economic Services Ltd.
Desalination and Water Treatment | Year: 2013

Israel's master plan for integrating large-scale seawater desalination plants within the national water supply system was drafted in the year 1997. This master plan sought not only to minimize the costs of these additional water sources, inter alia through plant siting, economies of scale, and maximizing utilization of existing infrastructures, but also to maximize their benefits. Some of the benefits, particularly those resulting from higher product water quality requirements, justified, on a cost-benefit ratio basis, corresponding slight increases in the costs of desalinated water production. At the end of 2011, desalinated seawater was supplied continuously and reliably into the regional and national water grids from three large plants, Ashkelon, Palmachim, and Hadera, at the rate of about 300 million m3/year. This quantity represented about 42% of all the potable water inputs into these grids (other inputs were groundwater and Sea of Galilee water). In three years, by the end of 2014, two additional large plants, at Soreq A and Ashdod, and an expanded Palmachim plant will be producing an additional 300 million m3/year. The paper revisits the benefits foreseen in the original desalination master plan, quantifies them on the basis of actual data accumulated over the past year and some new studies on the economic effects of water shortages and water supply quality, compares them with past expectations, and projects them to 2014, when about 80% of grid supplied water will be desalinated seawater. © 2013 Desalination Publications.

Gasser G.,Hebrew University of Jerusalem | Pankratov I.,Israel Water Authority | Elhanany S.,Israel Water Authority | Glazman H.,Israel Nature and Parks Authority | Lev O.,Hebrew University of Jerusalem
Water Resources Research | Year: 2014

A methodology used to estimate the percentage of wastewater effluent in an otherwise pristine water site is proposed on the basis of the weighted mean of the level of a consortium of indicator pollutants. This method considers the levels of uncertainty in the evaluation of each of the indicators in the site, potential effluent sources, and uncontaminated surroundings. A detailed demonstrative study was conducted on a site that is potentially subject to wastewater leakage. The research concentrated on several perched springs that are influenced to an unknown extent by agricultural communities. A comparison was made to a heavily contaminated site receiving wastewater effluent and surface water runoff. We investigated six springs in two nearby ridges where fecal contamination was detected in the past; the major sources of pollution in the area have since been diverted to a wastewater treatment system. We used chloride, acesulfame, and carbamazepine as domestic pollution tracers. Good correlation (R2 > 0.86) was observed between the mixing ratio predictions based on the two organic tracers (the slope of the linear regression was 1.05), whereas the chloride predictions differed considerably. This methodology is potentially useful, particularly for cases in which detailed hydrological modeling is unavailable but in which quantification of wastewater penetration is required. We demonstrate that the use of more than one tracer for estimation of the mixing ratio reduces the combined uncertainty level associated with the estimate and can also help to disqualify biased tracers. Key Points A protocol for quantification of wastewater leakage to water sources Uncertainty-based weighted average of several domestic wastewater tracers Comparison of acesulfame, carbamazepine, and Cl- wastewater tracers © 2014. American Geophysical Union. All Rights Reserved.

Gasser G.,Hebrew University of Jerusalem | Rona M.,Hebrew University of Jerusalem | Voloshenko A.,Hebrew University of Jerusalem | Shelkov R.,Hebrew University of Jerusalem | And 5 more authors.
Desalination | Year: 2011

A quantitative approach for calculation of the percentage of water of domestic wastewater origin in contaminated water wells is presented. The article is an extension of a reported approach to quantify leakage from a wastewater recharge facility to nearby water wells pumping predominantly from a pristine aquifer. The relative contamination from a specific source, a wastewater recharge basin, and the contamination from unspecified domestic wastewater sources under near steady state conditions are calculated for several water wells in the vicinity of a wastewater recharge system. Carbamazepine (CBZ), an antiepileptic drug whose refractory behaviour was reported before is evaluated as a tracer. It is demonstrated that CBZ fulfils the requirements of source-specific as well as non-specific wastewater tracer, under Israeli conditions. In addition to being biodegradation-resistant, a survey of the effluents of domestic wastewater treatment plants in Israel revealed that the CBZ level is roughly constant, 1407 ± 204. ng/L in a wide range of water treatment facilities all over Israel. As such, at least for specific sites (e.g. Israel) CBZ can be used as a quantitative tracer for estimation of the fraction of effluent-originated water in water wells, and the uncertainty involved in such estimates can be calculated. © 2011 Elsevier B.V.

Ronen D.,Israel Water Authority | Ronen D.,Ben - Gurion University of the Negev | Sorek S.,Ben - Gurion University of the Negev | Gilron J.,Ben - Gurion University of the Negev
Ground Water | Year: 2012

This issue paper presents how certain policies regarding management of groundwater quality lead to unexpected and undesirable results, despite being backed by seemingly reasonable assumptions. This happened in part because the so-called reasonable decisions were not based on an integrative and quantitative methodology. The policies surveyed here are: (1) implementation of a program for aquifer restoration to pristine conditions followed, after failure, by leaving it to natural attenuation; (2) the "Forget About The Aquifer" (FATA) approach, while ignoring possible damage that contaminated groundwater can inflict on the other environmental systems; (3) groundwater recharge in municipal areas while neglecting the presence of contaminants in the unsaturated zone and conditions exerted by upper impervious surfaces; (4) the Soil Aquifer Treatment (SAT) practice considering aquifers to be "filters of infinite capacity"; and (5) focusing on well contamination vs. aquifer contamination to conveniently defer grappling with the problem of the aquifer as a whole. Possible reasons for the failure of these seemingly rational policies are: (1) the characteristic times of processes associated with groundwater that are usually orders of magnitude greater than the residence times of decision makers in their managerial position; (2) proliferation of improperly trained "groundwater experts" or policymakers with sectoral agendas alongside legitimate differences of opinion among groundwater scientists; (3) the neglect of the cyclic nature of natural phenomena; and (4) ignoring future long-term costs because of immediate costs. © 2011, The Author(s). Ground Water © 2011, National Ground Water Association.

PubMed | Israel Water Authority
Type: Journal Article | Journal: Water research | Year: 2010

Concentrations of chlorinated volatile organic compounds (Cl-VOCs) at the saturated-unsaturated interface region (SUIR; depth of approximately 18m) of a sandy phreatic aquifer were measured in two monitoring wells located 25m apart. The concentrations of the Cl-VOCs obtained above and below the water table along a 413-day period are interpreted to depict variable, simultaneous and independent movement of trichlorothene, tetrachloroethene, 1,1-dichloroethene, cis-1,2-dichloroethene, 1,1,1-trichloroethane, chloroform and 1,1-dichloroethane vapors in opposite directions across the SUIR.

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