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1.
Yair Rinat Ari Matmon Maurice Arnold Georges Aumaître Didier Bourlès Karim Keddadouche Naomi Porat Efrat Morin Robert C. Finkel 《Quaternary Research》2014
Rockfall ages in tectonically active regions provide information regarding frequency and magnitude of earthquakes. In the hyper-arid environment of the Dead Sea fault (DSF), southern Israel, rockfalls are most probably triggered by earthquakes. We dated rockfalls along the western margin of the DSF using terrestrial cosmogenic nuclides (TCN). At each rockfall site, samples were collected from simultaneously exposed conjugate boulders and cliff surfaces. Such conjugate samples initially had identical pre-fall (“inherited”) TCN concentrations. After boulder detachment, these surfaces were dosed by different production rates due to differences in post-fall shielding and geometry. However, in our study area, pre-rockfall inheritance and post-rockfall production rates of TCN cannot be evaluated. Therefore, we developed a numerical approach and demonstrated a way to overcome the above-mentioned problems. This approach can be applied in other settings where rockfalls cannot be dated by simple exposure dating. Results suggest rockfall ages between 3.6 ± 0.8 and 4.7 ± 0.7 ka. OSL ages of sediment accumulated behind the boulders range between 0.6 ± 0.1 and 3.4 ± 1.4 ka and support the TCN results. Our ages agree with dated earthquakes determined in paleoseismic studies along the entire length of the DSF and support the observation of intensive earthquake activity around 4–5 ka. 相似文献
2.
Efrat Farber Ittai Gavrieli Thomas D. Bullen Ran Holtzman Uri Shavit 《Geochimica et cosmochimica acta》2004,68(9):1989-2006
The chemical and isotopic (87Sr/86Sr, δ11B, δ34Ssulfate, δ18Owater, δ15Nnitrate) compositions of water from the Lower Jordan River and its major tributaries between the Sea of Galilee and the Dead Sea were determined in order to reveal the origin of the salinity of the Jordan River. We identified three separate hydrological zones along the flow of the river:
- (1)
- A northern section (20 km downstream of its source) where the base flow composed of diverted saline and wastewaters is modified due to discharge of shallow sulfate-rich groundwater, characterized by low 87Sr/86Sr (0.7072), δ34Ssulfate (−2‰), high δ11B (∼36‰), δ15Nnitrate (∼15‰) and high δ18Owater (−2 to-3‰) values. The shallow groundwater is derived from agricultural drainage water mixed with natural saline groundwater and discharges to both the Jordan and Yarmouk rivers. The contribution of the groundwater component in the Jordan River flow, deduced from mixing relationships of solutes and strontium isotopes, varies from 20 to 50% of the total flow.
- (2)
- A central zone (20-50 km downstream from its source) where salt variations are minimal and the rise of 87Sr/86Sr and SO4/Cl ratios reflects predominance of eastern surface water flows.
- (3)
- A southern section (50-100 km downstream of its source) where the total dissolved solids of the Jordan River increase, particularly during the spring (70-80 km) and summer (80-100 km) to values as high as 11.1 g/L. Variations in the chemical and isotopic compositions of river water along the southern section suggest that the Zarqa River (87Sr/86Sr∼0.70865; δ11B∼25‰) has a negligible affect on the Jordan River. Instead, the river quality is influenced primarily by groundwater discharge composed of sulfate-rich saline groundwater (Cl-=31-180 mM; SO4/Cl∼0.2-0.5; Br/Cl∼2-3×10-3; 87Sr/86Sr∼0.70805; δ11B∼30‰; δ15Nnitrate ∼17‰, δ34Ssulfate=4-10‰), and Ca-chloride Rift valley brines (Cl-=846-1500 mM; Br/Cl∼6-8×10-3; 87Sr/86Sr∼0.7080; δ11B>40‰; δ34Ssulfate=4-10‰). Mixing calculations indicate that the groundwater discharged to the river is composed of varying proportions of brines and sulfate-rich saline groundwater. Solute mass balance calculations point to a ∼10% contribution of saline groundwater (Cl−=282 to 564 mM) to the river. A high nitrate level (up to 2.5 mM) in the groundwater suggests that drainage of wastewater derived irrigation water is an important source for the groundwater. This irrigation water appears to leach Pleistocene sediments of the Jordan Valley resulting in elevated sulfate contents and altered strontium and boron isotopic compositions of the groundwater that in turn impacts the water quality of the lower Jordan River.
3.
In ancient times human activities were tightly related and sensitive to rainfall amounts and seasonal distribution. East Mediterranean settlements were concentrated around numerous small to large springs, such as the Judean Mountains area. The goals of this study were to determine (a) the sensitivity of total discharge, recession curve, and response time of such springs to annual precipitation patterns, and (b) how spring hydrology responds to series of drought or wet years and to transitions from drought to normal and/or wet episodes (and vice versa). These goals were achieved by setting a finite-element hydro-geological flow model for selected perched springs that characterize the numerous springs throughout the carbonate karst terrain in the Judean Mountains. In addition, we estimated the effect of proposed regional past climate changes on the springs; in so doing, we transfer climate change to community size, livelihood and economic strength that were highly dependent on agricultural productivity. The results of the hydro-geological model revealed that these mountainous communities had the potential to prosper during historically wetter episodes and were probably adapted to short-term variability in annual rainfall. However, moderate to extreme droughts lasting only a few years could have led to a partial or even total abandonment of the springs as focal sites of intensive agricultural production. Spring drying eliminated the primary cause for the location of settlement. This occurred simultaneously in numerous settlements around the mountains of the southern Levant and therefore, must have caused dramatic economic and societal changes in the entire region, perhaps even resonating afar. 相似文献
4.
Dr. E. Efrat 《GeoJournal》1978,2(6):507-519
Israel's town system consists of 37 towns of different size, 28 development towns, and 24 semi-urban Jewish and Arab settlements, most of them consisting of 5,000–10,000 inhabitants. In the existing town system there is an exaggerated concentration of large towns in the Tel Aviv region; an excessive number of development towns; slow urban growth in the Negev and the Galilee; failure of semi-urban settlements to attain urban status; and the absence of urban settlements in many regions where they would be needed.A proposal to outline an optimal system of Israel's town development is discussed. It was found that the existing urban system in Israel shows a distortion which is four times bigger than the optimal one. A comparison between the optimal lay-out of towns and the real one uncovers the gaps where new towns should be established in the future, and points out the locations where no further urban development should be encouraged. 相似文献
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6.
Spatial patterns in thunderstorm rainfall events and their coupling with watershed hydrological response 总被引：1，自引：0，他引：1
Efrat Morin David C. Goodrich Robert A. Maddox Xiaogang Gao Hoshin V. Gupta Soroosh Sorooshian 《Advances in water resources》2006
Weather radar systems provide detailed information on spatial rainfall patterns known to play a significant role in runoff generation processes. In the current study, we present an innovative approach to exploit spatial rainfall information of air mass thunderstorms and link it with a watershed hydrological model. Observed radar data are decomposed into sets of rain cells conceptualized as circular Gaussian elements and the associated rain cell parameters, namely, location, maximal intensity and decay factor, are input into a hydrological model. Rain cells were retrieved from radar data for several thunderstorms over southern Arizona. Spatial characteristics of the resulting rain fields were evaluated using data from a dense rain gauge network. For an extreme case study in a semi-arid watershed, rain cells were derived and fed as input into a hydrological model to compute runoff response. A major factor in this event was found to be a single intense rain cell (out of the five cells decomposed from the storm). The path of this cell near watershed tributaries and toward the outlet enhanced generation of high flow. Furthermore, sensitivity analysis to cell characteristics indicated that peak discharge could be a factor of two higher if the cell was initiated just a few kilometers aside. 相似文献
7.
Efrat E 《GeoJournal》1991,24(4):355-363
The State of Israel is facing now one of the most difficult absorption challenges it has ever had. About 250.000 Soviet-Jewish immigrants have arrived to the country since 1989 and another million are waiting in the Soviet Union for immigration. A direct absorption plan around an absorption basket of a few thousand dollar per family of three for the first year enables the immigrants to choose their place of habitation. They concentrate in big cities and veteran settlements along the coastal plain where employment possibilities are better. This trend is against the government's plans to direct them to peripheral regions. The current mass-immigration creates an unexpected change in the population and settlement pattern of Israel. 相似文献
8.
Elisha Efrat 《GeoJournal》1993,31(2):163-168
During the Gulf War Israel was divided into six alarm zones to enable the people to be released gradually from their shelters according to the rate of damage and danger which has been in the different regions. These zones were outlined superficially, neither according to basic geographical elements, nor to the ballistic behaviour of the Iraqi missiles. A modified division into ten alarm zones was announced in September 1992 following the blockade which the USA had laid on military aviation in southern Iraq. A different division of alarm zones, based on ballistic and geographical parameters is proposed should there be missile attacks on the country in the future. 相似文献
9.
Prof. Dr. Elisha Efrat 《GeoJournal》1977,1(4):41-46
Conclusions The industrialization of the development towns is one of the main factors in the creation of a modern productive economy in a new social environment. The proportion of Israel's large industrial plants that have been located in the developments town is much larger than the corresponding proportion of all the country's industries. The tendency to establish relatively large industries in the development towns will probably continue for a considerable time, and it will necessitate the chanelling of large government resources to the development regions.A more serious obstacle is the shortage of labour, and particularly of skilled labour. In contrast to the supply of capital, this difficulty cannot be solved by administrative decisions taken in accordance with an agreed economic policy. What is needed here is a revolution in vocational training, and a diversification in plant sizes, the smaller plants supplying services to the larger industries.Vocational education is one of the most important conditions for the success of the industrialization process in the development towns. Jews have no technological and industrial tradition, and when they established their state, they did not attach sufficient importance to the rapid training of a labour force that would be able to take its place in the new factories. In making up for this omission, it is important to avoid concentrating on the conservative and traditional trades, and attention should be paid to the needs of the newer and more sophisticated industries. 相似文献
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