Hydrochemical assessment of a deep Jordanian aquifer

 This paper was mainly initiated to estimate some parameters of the quality and hydraulics of water in the vicinity of a proposed dam site in Jordan. The assessment of the chemical character was carried out to examine the suitability of the groundwater for domestic, municipal, industrial or irrigation use. Also, the anticipated problems associated with the quality of the reservoir water were delineated. Pumping tests were conducted at some wells that were drilled within the dam site zone and drawdown-time curves were constructed, by means of which the transmissivity and storage coefficients were assessed using two different methods. Total dissolved solids and electrical conductance were also measured and the relationship between them established. In addition, sodium ion concentrations at different piezometric tip elevations were measured in a number of wells that were previously drilled inside the dam site zone. This data indicates that the water quality as expressed in terms of total dissolved solids, electrical conductance, and sodium ion concentration limits do not comply with internationally recommended standards. The usage of this water for usual domestic purposes is therefore not viable, while the utilization of this water for irrigation purposes is very restricted. Received: 1 September 1995 · Accepted: 2 April 1995     

Marine Stone Columns to Prevent Earthquake Induced Soil Liquefaction

With ports and other near shore structures expanding, and regions previously not considered prone to earthquakes being re-classified after recent earthquake events, ground improvement by stone columns is increasingly considered to improve loose or soft in situ soils. The Dry Bottom Feed Stone Column construction technique can be used under water if a double-lock stone delivery system is attached to the vibroprobe. The use of pneumatic stone transport from the barge into the vibroprobe receiver tank makes it possible to reach large water and treatment depths. Digital recording of all relevant operation parameters provides a very high level of quality assurance, including a diameter-over-depth profile for each stone column. An introduction to earthquake-resistant design of stone columns and guidelines for specifying Marine Stone Columns are given.     

Geological and hydrological investigation of a water collection system in arid Jordanian lands

With the increase in population of developing and under developed countries, and with the availability of water resources strained and in many areas deficient, it is quite evident that water conservation and distribution programs need to be adopted on a scale far greater than any yet in use. This requires a more detailed evaluation and development of any water resource. In this study, the geology and geomorphology of the Safawi area northeast of Jordan and the climatic conditions were evaluated as an aid in determining the potential for the collection of surface water. The runoff coefficient, flood frequency, and runoff volumes from some selected valleys were determined through the use of the Soil Conservation Service (SCS) method and other known techniques. The results of this study indicated that the collection of surface water in this arid region is feasible. Estimates were made for the runoff coefficient and annual runoff volumes through the application of the accepted hydraulic engineering methods.     

Geologic problems related to dam sites in Jordan and their solutions

The geologic structures associated with several selected dam sites in Jordan and the tectonic effects on dam foundations and reservoir margins are reviewed. Rock defects, especially discontinuities represented by faults and closely spaced, open joints are investigated. Related problems, such as loss of water from the reservoir by seepage and leakage within the dam foundation are evaluated. The regional seismicity is analyzed and a design earthquake is established for each dam site.

Two major embankment dams are investigated, together with two large proposed dams and several small dams.

This paper discusses in some detail the regional setting and site-specific geology, and the occurrence, size and inclination of faults and joints at each dam site. Moreover, the effects of the faults on the operational performance of each dam are described and specific techniques are used or proposed for remediation are outlined.

The study shows that the combination of faults and joint features cause leakage problems at the operational dams in Jordan. Although, preventive measures such as grouting have been implemented, further leakage and/or seepage problems are anticipated and a monitoring system is needed to control and foresee such problems.

Jordan is an earthquake-prone region. Consequently, it is recommended that the design of embankment dams in the vicinity of the Dead Sea-Jordan Valley Rift should include such considerations as dynamic loading and associated hazards, including embankment acceleration zoning, foundation liquefaction risk and rockhead rupture. The magnitude of the design earthquake at each dam site can be estimated following the guidelines of ICOLD (1989), which are based on probabilistic seismic hazard analysis.     

SARETL: an expert system for probabilistic displacement-based dynamic 3-D slope stability analysis and remediation of earthquake triggered landslides

 Different models were developed for evaluating the probabilistic three-dimensional (3-D) stability analysis of earth slopes and embankments under earthquake loading using both the safety factor and the displacement criteria of slope failure. In the 3-D analysis, the critical and total slope widths become two new and important parameters. The probabilistic models evaluate the probability of failure under seismic loading and consider the different sources of uncertainties involved in the problem, i.e. uncertainties stemming from the discrepancies between laboratory-measured and in situ values of shear strength parameters, randomness of earthquake occurrence, and earthquake-induced acceleration. The models also take into consideration the spatial variabilities and correlations of soil properties. The developed models are incorporated in a computer program, PTDDSSA (probabilistic three-dimensional dynamic slope stability analysis). These developed analysis/design procedures are incorporated within a code named SARETL (stability analysis and remediation of earthquake-triggered landslides) that was developed in this study for stability analysis and remediation of earthquake-triggered landslides. In addition to the dynamic inertia forces; the developed system takes into consideration the local site effects. The code is capable of: 1. Prediction of permanent deformations that result from landslides under seismic loading using both probabilistic and deterministic approaches. 2. The assessment of landslide hazard that affects major transportation routes in the event of earthquakes, and the preparation of earthquake-induced landslide hazard maps (i.e. maps that show expected displacements and probability of slope/embankments failure) for different earthquakes magnitudes and environmental conditions. 3. Proposing a mitigation strategy against landslides and suggesting guidelines for remedial measures. The developed expert system is applied to a major highway case study. Design maps are developed for the highway under seismic loading. Received: 18 March 1999 · Accepted: 11 October 1999     

Geology,geomorphology, hydrology,groundwater and physical resources of the desertified Badia environment in Jordan

This paper summarizes the information on the geomorphology and physical resources component of the Jordan Badia Research and Development Programme. The research focuses on the issue of the environment in arid lands and aims to provide practical options for sustainable development, for the benefit not only of the Hashemite Kingdom of Jordan but for other arid regions of the world. The research is significantly development driven because there is a need to identify useable natural resources and establish a framework for their effective exploitation and management in a marginal, fragile environment, which is sensitive to change.Pressure for development of the Badia stems from the fact that the great majority of the population in Jordan is compressed into less than 10% of the country by environmental constraits. It is hoped that the Jordan Badia Research and Development Programme will provide the required framework to ease current environmental pressures, encourage migration to the Badia, a sparsely populated region, and establish economically and ecologically self-supporting communities.This paper discusses the following areas that are related to the sustainable development of the Jordan Badia with special emphasis on the Safawi area in the Northern Jordan Badia; geomorphology including landform, processes and hazards, geology and physical resources, hydrology, surface water and water engineering, groundwater, soils and vegetation, sediment erosion and mobility and environmental management.     

In-situ geotechnical experimentation and stability evaluation of an instrumented 180 m×70 m×12.5 m fill dike constructed on laminated soft ground

 An instrumented trial-fill dike was constructed on soft, laminated soils of the Lisan Peninsula foreshore of the Dead Sea. The earthwork had base dimensions of 180 m by approximately 70 m wide and was raised in two stages to a maximum height of 12.5 m above original ground level. The geotechnical data of the dike were monitored in order to: assess the short- and long-term strength of the foundation, obtain and analyze the pore-pressure response of the foundation soils for potential use in construction control, obtain data on embankment settlement in order to refine end-of-construction and post-construction settlement assessments, and optimize the height of the dike to be constructed by providing information on the construction sequence for use in calculation of capital costs and alternative layouts and dike heights. The successful completion of the trial dike has demonstrated that steep-side dikes up to 12.5 m high can be constructed rapidly on soft soils. The construction of the trial dike has therefore proved a very substantial benefit to the evaluation of the likely performance of a dike constructed along the Lisan shore. The key factor which made this fast construction possible was the unexpected, very rapid consolidation of the majority of the foundation soil which has been shown to occur. The principal observations from the trial dike were: (1) end of construction settlements may be calculated using drained stiffnesses where E′/s_{u initial} has a value of around 65; (2) post-construction settlements can be calculated using a coefficient of secondary compression, Cα equal to 0.015; (3) a rapid increase in undrained shear strength occurred when loading the soil up to a value of s_u equal to around 30 kPa. The value of s_u/σ_v′ was as high as 0.5 at this stage. With further loading the strength increase was more modest and s_u/σ_v fell to around 0.25 for a vertical effective stress of 160 kPa; (4) for the undrained stability analyses of the trial dike, the mean vane shear-strength profile provided an appropriate assessment of the short-term factor of safety against failure, 5) For the drained stability analyses of the trial dike, lower bound effective strength parameters for the foundation and embankment fill (c′=0, φ′=30° and c′=2 kN/m², φ′=33°, respectively), combined with field measurements of end of construction pore water pressures provided an analysis which was broadly compatible with the undrained analysis; and (6) the trial dike has been stable, pre- and post-construction, because of the well drained nature of its foundation which prevented the build up of high pore water pressures and led to rapid consolidation. Received: 22 June 1998 · Accepted: 30 October 1998     

CSEES: An expert system for analysis and design of cut slopes and embankments

 An expert system is developed for evaluating failure potential of cut slopes and embankments. The fuzzy sets theory is used with the modified Monte Carlo simulation technique to obtain the Slope Failure Potential Index (SFPI) incorporating factors affecting slope stability, such as geology, topography, geomorphology, precipitation, vegetation and drainage conditions. The developed Cut Slopes and Embankments Expert System (CSEES) includes a classification system for evaluating failure potential of cut slopes and embankments, and a data bank on landslides in Jordan. The proposed classification system and slope failure-potential method proved to be successful for the areas that experienced landslides in the past. The expert system can be used directly for areas with the same geological formations as those areas in which landslides occurred in the past and can be used for areas with other geological formations by modifying the rock type or foundation-material type factor incorporated in the expert system. Received: 18 February 1998 · Accepted: 19 October 1998     

A study on geology,geomorphology, hydrology,groundwater, and physical resources of the desertified Badia environment in Jordan towards sustainable development

This paper summarizes information on geomorphology and physical resources as a part of the Jordan Badia Research and Development Program. The research focused on the issue of the environment in arid lands as an aid to providing practical options for sustainable development, for the benefit not only of the Hashemite Kingdom of Jordan but of other arid regions of the world. The research is significant in that there is a need to identify usable natural resources and establish a framework for their effective exploitation and management in a marginal, fragile environment, which is sensitive to change. Pressure for development of the Badia stems from the fact that the great majority of the population in Jordan is compressed into less than 10% of the country by environmental constraints. It is hoped that the Jordan Badia Research and Development Program will provide the required framework to ease current environmental pressures, encourage migration to the Badia, a sparsely populated region, and establish economically and ecologically self-supporting communities. This paper discusses the following areas that are related to the sustainable development of the Jordan Badia with special emphasis on the Safawi area in the northern Jordan Badia; geomorphology, including landform, processes, and hazards; geology and physical resources; hydrology; surface water and water engineering; and groundwater.     

Analysis and remedies of landslides of cut slopes due to the presence of weak cohesive layers within stronger formations

 Several cases of instability of cut slopes along major highways in Jordan were reviewed in this study, in some detail. Emphasis was placed on the Amman-Irbid highway, but some cases along the Na'ur-Dead Sea highway were also reviewed, with the aim of establishing a wider database of case-studies and examining all possible mechanisms and factors influencing stability. The study showed that major cut slope failures were caused by the presence of weak cohesive layers (mainly clayey marl) interbedded within mostly stronger formations, in addition to the steep cutting angles and unfavorable dip of strata combined with relatively high piezometric surface brought about by poor surface and subsurface drainage. No remedies were implemented to stabilize major cut slope failures (at km 39+200, 44+300, and 56+400) along the Irbid-Jerash-Amman highway. The three major cut slope failures require extensive remedial work and probably advanced geotechnology, which is expected to be expensive. To investigate the influence of various parameters on slope stability, several analyses were performed in addition to back analyses to determine shear strength parameters; parametric sensitivity studies were also performed on some cases. Data was obtained from previous investigations by local and international firms and were screened and modified where needed before being used in stability analyses. Considerable difference between back analysis and test result values for shear strength parameters were observed in many cases. Failure surfaces and mechanisms were accurately depicted in most cases, allowing back analyses to be performed with considerable confidence. The effective residual shear strength parameters for clayey marl needed for stability analysis were found to be: c _r ′=5–18 kPa, and φ _r ′=13°–18°. The relation between total annual rainfall and occurrence of landslides was investigated; it was shown that all landslides occurred in years of very high rainfall, with values always exceeding 400 mm. The probability of exceeding the average total annual rainfall was found to be approximately 0.42 for the three gauging stations considered. Received: 28 October 1996 · Accepted: 23 September 1997