USE OF TRITIUM IN HYDROLOGY

SUMMARY

The Coastal Plain aquifer of Israel, of Plio-Pleistocene Age, stretches from Binyamina in the North to the Gaza Strip in the South-a distance of about 112 km and has an average width of about 15 Km. The allowed withdrawal is estimated at about 200 MCM/year.

As a result of an average yearly withdrawal of 426 MCM/year during the last 10 years the water levels dropped to a dangerously low position (-2)-(-4) m below sea level at distances of 3–5 Km from the coast, causing sea water intrusion which, in Tel Aviv and Emek Hefer, endangered water supply wells.

As a counter-measure, artificial groundwater recharge through wells was practiced in Emek Hefer since 1959. Recharge was practiced in 7 wells at a rate of 6 MCM/year, the water coming from adjacent Cretaceous limestone aquifers.

In Tel Aviv a fresh water barrier was established in 1964 by injecting Lake Kinereth water into 17 wells during winter at a rate of 6 MCM/winter. In the rest of the Coastal Plain water was injected to the aquifer through about 40–45 wells at a total yearly rate of about 10–12 MCM.

Recharge by spreading is practiced in Yavneh at a rate of about 10–13 MCM per winter, also recharge by spreading is practiced with flood water of Nahal Shikma at a rate of up to 8 MCM/winter.     

SEDIMENT YIELD AND HYDROLOGY IN NORTHWESTERN RANGELANDS

lINTRODUCTIONRangeandforestlandsofnorthwesternNorthAmericahavebeenutilizedforres0urceextracti0nandproductionsinceinitialhuman0ccupationofthecontinent.Intensive"managed"utilizati0nofec0systemsforspecificbenefitsincludingcattle,sheep,t1sh,w00dandagriculturalpr0ductshasbeenong0ingfornearly0ne-and-haIfcenturies.Intensiveresourceproducti0nhasto0oftenbeenacc0mpaniedbyunwanted"sideeffects"includingacceleratederosion,s0illossandsedimentdeliveredoffsitetod0wnstreamlocati0ns,estuariesandoceanicsin…     

USING A COMBINED SLOPE HYDROLOGY/STABILITY MODEL TO IDENTIFY SUITABLE CONDITIONS FOR LANDSLIDE PREVENTION BY VEGETATION IN THE HUMID TROPICS

The susceptibility of cut slopes to landsliding can be reduced in certain circumstances by the establishment of a vegetation cover. However, the hydrological implications of allowing a cover to develop may offset the mechanical benefits of soil reinforcement by roots. The balance between hydrological and mechanical effects is critical on slopes which are susceptible to the development of an infiltration-induced transitory perched water table, a common cause of landslides in deep, tropical residual soils. This balance is likely to change both between slopes of different types as well as temporally on any given slope. The net effect of a vegetation cover must be predicted either before natural vegetation covers are allowed to encroach on bare slopes, or if engineers are considering the use of trees as a protective measure. This paper presents a method of calculating the impact of a vegetation cover on slope stability. Simulations carried out on a wide range of slope types suggest that where failure is most likely to be triggered by infiltration rather than ground water rise, large-scale vegetation covers may contribute to instability. Whether vegetation had a positive or negative impact on slope stability was controlled by the permeability of the soil matrix, whilst the magnitude of impact was controlled by the soil strength and the slope height.     

THE USE OF BOREHOLE VIDEO IN INVESTIGATING THE HYDROLOGY OF A TEMPERATE GLACIER

A GeoVision Micro™ colour video camera was used to investigate the internal structure of 11 boreholes at Haut Glacier d'Arolla, Switzerland. The boreholes were distributed across a half-section of the glacier, with closest spacing towards the glacier margin. The boreholes were used to investigate the hydrology of the glacier through automatic monitoring of borehole water level and electrical conductivity (EC) at the glacier bed. EC profiling was undertaken in several boreholes to determine the existence of water quality stratification. Temporal variations in EC stratification were used to infer borehole water sources and patterns of water circulation. Borehole video was used to confirm the conclusions made from these indirect sources of evidence, and to provide an independent source of information on the structure and hydrology of this temperate valley glacier. The video showed variations in water turbidity, englacial channels and voids, conditions at the glacier bed and down-borehole changes in ice structure. Based on the video observations, englacial channels accounted for approximately 0·1% of the vertical ice thickness, and englacial voids for approximately 0·4%. Overall, the video images provided useful qualitative and semi-quantitative data that reinforce interpretations of a range of physical and chemical parameters measured in boreholes. © 1997 by John Wiley & Sons Ltd.     

THE USE OF ENTROPY IN HYDROLOGY AND WATER RESOURCES

Since the development of the entropy theory by Shannon in the late 1940s and of the principle of maximum entropy (POME) by Jaynes in the late 1950s there has been a proliferation of applications of entropy in a wide spectrum of areas, including hydrological and environmental sciences. The real impetus to entropy-based hydrological modelling was provided by Amorocho and Espildora in 1972. A great variety of entropy applications in hydrology and water resources have since been reported, and new applications continue to unfold. This paper reviews the recent contributions on entropy applications in hydrology and water resources, discusses the usefulness and versatility of the entropy concept, and reflects on the strengths and limitations of this concept. The paper concludes with comments on its implications in developing countries. © 1997 by John Wiley & Sons, Ltd.     

宁夏及邻区一年尺度中强地震综合预测方案研究

在对宁夏及邻区5.0级以上中强地震进行清理基础上，分析了本区中强地震前的地震活动性参数异常。给出了5级以上地震综合预测方案。     

INTEGRATED MANAGEMENT PLAN OF SEDIMENT AND ECOLOGICAL RESTORATION IN WATERSHEDS, A CASE STUDY IN CHINA

1 INTRODUCTION Soil erosion is serious in Western China. With the implementation of a development strategy for western China, soil and water conservation and ecological restoration in western China earn more attention because economic development requires parallel efforts on ecological restoration. To protect the ecology of the upper reaches of the Yangtze River, integrated management of sediment and ecological restoration are being conducted in Sichuan Province. The Yufeng Watershed…     

国际港口结构抗震设计标准

从设计思想、设计方法和设计步骤等方面介绍了国际航海协会制定的国际港口结构抗震设计标准。该设计标准全面引入了性态设计的思想，对不同港口结构在不同地基基础条件下的地震反应给予考虑。在应用上，该标准同时具有成熟性和灵活性，对于从事相关设计的人员是一种有益的参考。     

国际绝对重力仪比对述评

本文述评了各国绝对重力仪过去历次国际比对结果,并对今后国际大比对提出某些建议。     

国际绝对重力仪比对述评

本文述评了各国绝对重力仪过去历次国际比对结果,并对今后国际大比对提出某些建议。