Vulnerability and adaptation in a dryland community of the Elqui Valley, Chile

Livelihoods in drylands are already challenged by the demands of climate variability, and climate change is expected to have further implications for water resource availability in these regions. This paper characterizes the vulnerability of an irrigation-dependent agricultural community located in the Elqui River Basin of Northern Chile to water and climate-related conditions in light of climate change. The paper documents the exposures and sensitivities faced by the community in light of current water shortages, and identifies their ability to manage these exposures under a changing climate. The IPCC identifies potentially increased aridity in this region with climate change; furthermore, the Elqui River is fed by snowmelt and glaciers, and its flows will be affected by a warming climate. Community vulnerability occurs within a broader physical, economic, political and social context, and vulnerability in the community varies amongst occupations, resource uses and accessibility to water resources, making some more susceptible to changing conditions in the future. This case study highlights the need for adaptation to current land and water management practices to maintain livelihoods in the face of changes many people are not expecting.     

Elasto‐plastic seepage‐induced stresses due to tunneling

When tunneling is carried out beneath the groundwater table, hydraulic boundary is altered, resulting in seepage entering into the tunnel. The development of flow into the tunnel induces seepage stresses in the ground and the lining is subjected to additional loads. This can often cause fine particles to move, which clog the filter resulting in the long‐term hydraulic deterioration of the drainage system. However, the effect of seepage force is generally not considered in the analysis of tunnel. While several elastic solutions have been proposed by assuming seepage in an elastic medium, stress solutions have not been considered for the seepage force in a porous elasto‐plastic medium. This paper documents a study that investigates the stress behavior, caused by seepage, of a tunnel in an elasto‐plastic ground and its effects on the tunnel and ground. New elasto‐plastic solutions that adopt the Mohr–Coulomb failure criterion are proposed for a circular tunnel under radial flow conditions. A simple solution based on the hydraulic gradient obtained from a numerical parametric study is also proposed for practical use. It should be noted that the simple equation is useful for acquiring additional insight into a problem on a tunnel under drainage, because only a minimal computational effort is needed and considerable economic benefits can be gained by using it in the preliminary stage of tunnel design. The proposed equations were partly validated by numerical analysis, and their applicability is illustrated and discussed using an example problem. Comments on the tunnel analysis are also provided. Copyright © 2010 John Wiley & Sons, Ltd.     

Adapting visual methods: action research with Kampala street children

The paper examines the use of four visual 'action' methods for eliciting information from street children about their interactions with the socio-spatial environment. These methods were adapted and used to encourage child-led activities and minimize researcher input. The advantages and constraints associated with the successful implementation of visual methods with children are examined, followed by a brief examination of the 'real' and ethical considerations surrounding their use. The paper concludes that visual methods allow a high level of child-led participation in research, as well as providing a stimulus for eliciting further oral material.     

Characterization of High-K Pathways by Borehole Flowmeter and Tracer Tests

This paper reviews different borehole flowmeter analysis methods and evaluates their applicability to a test site composed of fluvial deposits. Results from tracer and aquifer tests indicate that the aquifer is highly heterogeneous and that low-K skin effects exist at the wells. Borehole flowmeter tests were performed at 37 wells. An appropriate method for calculating borehole flowmeter K values was developed based on results from multiwell pumping tests, single-well pumping tests, and slug tests. The flowmeter data produced 881 K values. The trends and the magnitude of the K values are consistent with results from geologic investigations, recirculating tracer tests, and large-scale multiwell pumping tests. The field tests illustrate that high-K deposits can significantly affect ground-water flows in some heterogeneous fluvial aquifers.     

Improvements to Griggs-type apparatus for mechanical testing at high pressures and temperatures

New and improved techniques and apparatus for testing the mechanical properties of materials at high presures and temperatures are described. These include an improved Griggs-type deformation apparatus designed to operate to 5 GPa and associated servo-controlled hydraulic drive and electronics, the design of hydrostatic (molten alkali halide mixtures) pressure assemblies to measure flow stresses as low as a few MPa, the characterization of temperature gradients and friction in such assemblies, measurement of the melting curve of an alkali halide mixture used as a confining pressure medium, and the measurement of acoustic emissions.     

Stratigraphy,paleocurrents and stromatolites of Hadrynian (Upper Precambrian) rocks of Victoria Island,Arctic Archipelago,Canada

The Hadrynian (Upper Precambrian) rocks of Victoria Island in the western part of the Canadian Arctic Archipelago comprise a sedimentary sequence some 12,000 ft. (4,000 m) thick, capped by a 1,000 ft. (330 m)-thick basic volcanic and pyroclastic unit. These rocks outcrop in an elongate, topographic high called the Minto Arch, and in smaller inliers in Lower Paleozoic rocks in the south part of the island (Duke of York and Wellington highs).Stratigraphic and sedimentological investigation of these rocks in the southern part of the Wellington high near Cambridge Bay suggest that they were deposited by rivers flowing from a land mass that lay to the east. Clasts in the Hadrynian sedimentary rocks attest to the existence of at least two earlier periods of sedimentation and one phase of tectonic compression in the basement rocks.Study of the lower part of the Hadrynian succession (Glenelg and Reynolds Point Formations) in the northeastern part of the Minto Arch reveals a general thickening to the west. Rock types present include dolomite, limestone, siltstone, sandstone and shale deposited in a dominantly shallow marine environment together with some marine deltaic units and possibly distal fluvial deposits. Cross bedding and ripple-mark orientations suggest a paleoslope to the northwest. However, the pattern of cross-bedding distribution is complex with modes not only in the northwest quadrant, but also in the northeast and southwest quadrants, the latter possibly reflecting longshore currents in a generally shallow marine environment.Stromatolites are abundant in both formations studied. They are almost exclusively laterally linked shallow-dipping domes in the cherty dolomites of the Glenelg Formation. However the capping stromatolitic dolomite of this formation is composed of columnar stromatolites, as also are the abundant stromatolitic banks and reefs of the overlying Reynolds Point Formation. Elongate domes in the lower part of the Glenelg Formation have a preferred orientation in a northwest-southeast direction, perhaps reflecting tidal currents. The topmost stromatolitic unit of the Glenelg Formation in more easterly areas has large elongate mounds on its upper surface. Elongation of these mounds has a preferred orientation in a northeast-southwest direction. Possibly this orientation is related to longshore currents flowing along the depositional strike.The Hadrynian sediments of Victoria Island and areas to the south and west may have been deposited in a shallow embayment of the Upper Precambrian Sea, open to the northwest and in continuity with a wedge of sediment that thickened westward and extended along the length of the North American continent. There is some evidence to support the existence of three such embayments in the southern part of the Canadian Arctic Archipelago, separated and defined by northerly salients of older rocks of the Canadian Shield. These salients reflect an east-west tectonic stress on a very large scale.     

A Physically Based Approach for Estimating Hydraulic Conductivity from HPT Pressure and Flowrate

The hydraulic profiling tool (HPT) is widely used to generate profiles of relative permeability vs. depth. In this work, prior numerical modeling results are used to develop a relationship between probe advance rate V (cm/s), probe diameter D (cm), water injection rate Q (mL/min), corrected pressure P_c (psi), and hydraulic conductivity K (feet/d) ((1)) where E is an empirically derived hydraulic efficiency factor. The relationship is validated by 23 HPT profiles that, after averaging K vertically, were similar to slug test results in adjoining monitoring wells. The best fit value of E for these profiles was 2.02. This equation provides a physically based approach for generating hydraulic conductivity profiles with HPT tooling.