Landscape ecological and spatial impacts of climatic change in two areas in the Netherlands

The possible impact of climatic change on the water balance is analysed for the River Dommel and the Veluwe, an area drained by many very small brooks. A water balance is calculated for the winter and the summer period. With the help of four scenarios, based on GCMs, climate data from the dry year 1976 and land use scenarios the impact of climatic change and a possible superposed effect of acid precipitation is analysed. The results show that although the yearly changes in the water balance are small in some cases, in all cases the fluctuations in the water balance between winter and summer period increase. Changes in precipitation and evapotranspiration are multiplied in water storage and runoff. This will have consequences for water use planning and management.     

Response of North American Great Basin Lakes to Dansgaard–Oeschger oscillations

We correlate oscillations in the hydrologic and/or cryologic balances of four Great Basin surface-water systems with Dansgaard–Oeschger (D–O) events 2–12. This correlation is relatively strong at the location of the magnetic signature used to link the lake records, but becomes less well constrained with distance/time from the signature. Comparison of proxy glacial and hydrologic records from Owens and Pyramid lakes indicates that Sierran glacial advances occurred during times of relative dryness. If our hypothesized correlation between the lake-based records and the GISP2 δ¹⁸O record is correct, it suggests that North Atlantic D–O stades were associated with relatively cold and dry conditions and that interstades were associated with relatively warm and wet conditions throughout the Great Basin between 50,500 and 27,000 GISP2 yr B.P. The Great Basin lacustrine climate records reinforce the hypothesis that D–O events affected the climate throughout much of the Northern Hemisphere during marine isotope stages 2 and 3. However, the absolute phasing between lake-size and ice-core δ¹⁸O records remains difficult to determine.     

Publication practices in physical and human geography: a comment on Nigel Thrift’s ‘The future of geography’

This note expands on, and in some respects challenges, the distinction Thrift (Geoforum 33 (2002) 291) makes between the publication practices of young human and physical geographers. Evidence on highly-cited papers by eminent British geographers is used to suggest that human geographers have been publishing mainly in human-geography journals, but physical geographers in a wider range of outlets, for at least two decades; and that the most influential papers of all, human or physical, have generally been in multi- or inter-disciplinary journals. Publication in ‘non-geographical’ journals is desirable since it helps geographers have a wider impact. Conversely, the discipline is harmed if influential outsiders perceive geographers as only concerned with internal debates and seeking to impress each other.     

Closing the groundwater protection implementation gap

Complacency about drinking water security was the order of the day in the Province of Ontario, Canada, until the water supply of the community of Walkerton was contaminated in May 2000. Seven people died and 2300 became seriously ill when runoff from a nearby livestock farm contaminated an improperly constructed municipal well. The Walkerton tragedy, and similar incidents that have occurred in Ontario and elsewhere in North America and Europe during past decades, reflect serious implementation gaps in groundwater protection. In Ontario, many of these implementation gaps relate to shortfalls in local and provincial management capacity. Some local organizations are well served with skilled staff, leaders committed to groundwater protection, effective policies and plans, and sound databases. Unfortunately, many are not, particularly smaller communities in rural areas. Existing implementation gaps were exacerbated in the mid-1990s when the provincial government increased the responsibilities of local agencies while at the same time cutting funding and staffing levels in its own Ministry of the Environment. Recent local and provincial initiatives are beginning to close some implementation gaps. However, key challenges remain. This paper explores factors that shape local capacity for groundwater protection, and highlights ways in which capacity-related implementation gaps may be addressed. The focus is experiences in Ontario, Canada. However, lessons learned are broadly transferable. Chief among these are the importance of financial and technical support for delineation of source water protection zones; legal requirements for source water protection; senior government commitment and leadership; and enhanced local awareness of, and participation in, groundwater management.     

Discrete-element modelling of extensional fault-propagation folding above rigid basement fault blocks

We employed a discrete‐element technique to investigate the effects of cover strength and fault dip on the style of fault‐propagation folding above a blind normal fault. Deformation in the cover is initially characterised by an upward‐widening monocline that is often replaced, with continued slip on the basement fault, by a single, through‐going fault. Localisation on a single fault produces hangingwall synclines and footwall anticlines as a result of breaching of the earlier monocline and which do not represent ‘drag’ against the fault. As basement fault dip decreases the width of the monocline at the surface increases. Experiments varying the strength of the overburden material illustrate the control that cover strength has on both fault propagation and folding in the cover. Reduction of the strength of the cover results in: (1) the width of the monocline above the fault tip increasing, and (2) more marked footwall thinning and hangingwall thickening of beds. In contrast, an increase in cover strength results in a narrower monocline and rapid propagation of the basement fault into the cover. In multi‐layer (variable strength) experiments simultaneous faulting of competent layers and flow of weaker layers produces complex structural relationships. Faults in the cover die out up and down section and do not link to the basement fault at depth. Similarly, complex macroscopically ductile characteristics such as footwall thinning and hangingwall thickening can be juxtaposed against simple brittle fault cut‐offs. These relationships must be borne in mind when interpreting the field and seismic expression of such structures. We discuss the modelling results in terms of their implications for structural interpretation and the surficial expression of fault‐related folding in extensional settings.