Changes in stream channel morphology at tributary junctions,Lower Hunter Valley,New South Wales

Many empirically derived models of downstream changes in channel form are based on the concept of hydraulic geometry, whereby changes in channel morphological variables are related by a continuous power function to increasing discharge or its surrogate. However, changes in discharge throughout a drainage basin are normally concentrated at the junctions of stream channels. At junctions, the relationship between discharge and channel morphology is discontinuous. Some Lower Hunter Valley stream channels were surveyed upstream and downstream of tributary junctions. While significant regional downstream relationships were established, consistent trends at tributary junctions were not apparent from the data. It is possible that considerable scatter evident in ratios of change on either side of each junction was due to local within-site variability. In addition, the relative timing of discharge inputs and the nature of introduced sediment loads could be important in determining the magnitude and direction of channel change at tributary junctions. Interrelated changes in cross-sectional, profile and planform variables may be expected below junctions. The resultant channel morphology, in terms of these variables, might not be wholly determinate.     

Measuring reduction in stone tools: an ethnoarchaeological study of Gamo hidescrapers from Ethiopia

Stone tools were knapped, not built. This truism means that tools were reduced from larger pieces in the production process. But many tools were further reduced in use, to repair damage or as edges dulled. Reduction reduced size (trivially), but also changed the proportions among tools' elements or dimensions. Such allometric variation (change in proportion as a function of change in size) is useful to estimate the degree of reduction that tools experienced. Reduction itself is a measure of curation, a theoretical concept of great interest in lithic studies and Paleolithic archaeology. To determine the reduction that archaeological tools experienced, we must compare their size and proportions at first use to the same properties at discard that we directly measure. By now many size estimates can be made from discarded tools. Some are experimentally tested but few are validated using direct ethnoarchaeological controls. We validate two allometric reduction measures—ratios of plan area to thickness and of an estimate of original to discarded volume—against direct measures of use and reduction in ethnographic Gamo hidescrapers from Ethiopia.     

Underground drainage at Mole Creek,Tasmania

Complex patterns of groundwater flow exist in the Mole Creek karst area, Tasmania. Many surface drainage divides are breached underground The evolution of the drainage has been dominated by (I) the deflection of streams along the strike of the limestone beds; (2) progressive changes to hydraulic gradients; and (3) a history of climate change during the Quaternary that has seen drainage diverted underground by glaciers and/or by proglacial and periglacial sedimentation     

Policy Entrepreneurship and Policy Change

This article reviews the concept of policy entrepreneurship and its use in explaining policy change. Although the activities of policy entrepreneurs have received close attention in several studies, the concept of policy entrepreneurship is yet to be broadly integrated within analyses of policy change. To facilitate more integration of the concept, we here show how policy entrepreneurship can be understood within more encompassing theorizations of policy change: incrementalism, policy streams, institutionalism, punctuated equilibrium, and advocacy coalitions. Recent applications of policy entrepreneurship as a key explanation of policy change are presented as models for future work. Room exists for further conceptual development and empirical testing concerning policy entrepreneurship. Such work could be undertaken in studies of contemporary and historical policy change.     

‘Torrents of Terror’: the August 1998 Storm and the Magnitude,Frequency and Impact of Major Floods in the Illawarra Region of New South Wales

The Illawarra Region some 80 kilometres south of Sydney is characterised by a prominent coastal escarpment that rises to 700 m within 12 km of the coast and forms a locus for frequent, high intensity rainfall events. One of the most recent recorded events occurred on 17 August 1998 with rainfall intensities at several pluviometers exceeding 120 mm hr^‐1 over a duration of one hour, with up to 249 mm falling in 3.5 hours during the main storm burst. Detailed pluviometer data indicate that the storm was non‐stationary and moved down catchment producing a widespread zone of 120 mm hr^‐1 intensity rainfall over a 30 minute duration across mid‐lower catchment areas after similar intensity but longer duration rainfall in catchment headwaters. Slope‐area reconstructions of peak discharge indicate that small catchments on the escarpment within the zone of maximum intensity experienced close to 100% rainfall‐runoff relationships, with peak discharges correlated to short duration (<1 hr) peak rainfall intensities. Widespread erosion occurred particularly where urban development had encroached on natural water courses. Debris/hyperconcentrated flows originating from both anthropogenic and natural sediment sources caused damage to urban areas. This paper provides an overview of the spatial and temporal characteristics of the 17 August 1998 storm, the hydrologic and geomorphic response of the streams, and the nature of damage to urban areas. It reassesses the frequency of recent high‐magnitude rainfall/flood events in the region, discussing the relationships between rainfall intensities, estimates of flood magnitudes and stormwater channel capacities.     

Retracing Rivers and drawing swamps: Using a drawing tablet to reconstruct an historical hydroscape from army corps survey maps

Abstract

This article presents a novel geospatial approach to reconstructing and analyzing environmental change over extensive spatial and temporal scales, even in systems such as rivers and streams that are comparatively difficult to digitize. We used a drawing tablet and stylus to digitize features found on historical Army Corps maps across the spatially extensive landscape of the Lower Wabash River’s riparian zone, in Indiana and Illinois, USA. The methodology allows for an efficient reconstruction of sinuous and irregular environmental features, such as sloughs, and demonstrates the utility of digitizing historical maps to understand the evolution of surface water quantity and location across a landscape. We then compared these historical data to contemporary environmental datasets for the same study area to understand what changes have occurred over a 100?year period. This reveals that the hydroscape of the Lower Wabash River has been significantly altered by past human activity, notably through the reduction of swamps, wetlands, and sandbars, and the increase in drainage ditches and overall stream area. Notably, many of these historical alterations are not captured within current environmental datasets.     

TOWARDS A PRECISE DEFINITION OF DRAINAGE BASIN AXIS

The subjective nature of drainage basin axis or length properties commonly used in morphometric ratios has led to the development of a simple yet precise and independently reproduceable axial property herein called the basin vectorial axis. By definition it uses the vectorial properties of the highest and all second-highest Strahler streams whether or not geological control exists.     

Division of the waters: changing concepts of the continental divide, 1804–1844

One of the major features of the continental geography of North America that was still misunderstood at the beginning of the nineteenth century was the drainage system between the Mississippi River and the Pacific. At the beginning of the century, Americans thought of the drainage system as symmetrical, with all major streams heading in a common source region and flowing in several directions to the Mississippi, the Arctic, the Pacific and the Gulf of California. The desired water route across the continent was based upon this view. During the first half of the nineteenth century the concept of the common source region and the water route underwent revision. Geographical information from early explorers like Lewis and Clark and Pike reinforced the older theories but gradually gave way before more accurate data acquired by the men of the Rocky Mountain fur trade. The fur trade lore was tested by John Charles Frémont in the 1840's and a new image was developed, one of a continental divide rather than a common source region. Although the idea of a commercial route across the continent still persisted after Frémont, it was viewed as a land route, crossing the Continental Divide at South Pass, rather than one by water.     

Inter-regional migration and social change: a study of South East England based upon data from the Longitudinal Study

"Data from the [Office of Population Censuses and Surveys] Longitudinal Study are used to trace the social class effects of migration between the South East region and the rest of England and Wales in the period 1971-81. The analysis begins with the migration streams into and out of the South East of those people who were in the labour market (including the unemployed) at both census dates. The paper then proceeds to an analysis of the migration streams of those who entered or left the labour market between 1971 and 1981. Finally, the effects of the migration streams on the social class composition of both the South East and the rest of England and Wales are summarised. The results are interpreted in the light of debates about change in the British urban and regional system."     

Streams,Slopes, and Suburban Development

The percent of available relief in the form of free-face slope and the percent of valley width as floodplain change systematically throughout drainage networks in response to changes in network position. The energy level and discharge of streams at the bases of slopes may be assessed by means of a cumulative stream-ordering system wherein the stream order is directly related to discharge. Investigations of several small drainage basins on the rim of the Denver Basin, Colorado, by means of field measurements, interpretation of aerial photography, and operation of a computer model provide data that indicate that the distribution of near-channel slopes responds to changes in land use, and particularly to suburban development. Increasing suburban development causes increases in the size and frequency of both free faces and floodplains.     

From Lithics to Spatial and Social Organization: Interpreting the Lithic Distribution and Raw Material Composition at the Final Palaeolithic Site of Kettig (Central Rhineland,Germany)

During the Final Palaeolithic Federmessergruppen period, a wide range of siliceous raw materials was used in the Central Rhineland (Germany). Beside materials from the immediate region, exogenous resources such as flint from up to 100 km away in the Meuse drainage area and the moraines of the Saalian glaciation were exploited. At Kettig, the spatial distribution of different lithic raw materials and analysis of several categories of burnt finds allow the characterization of the settled area in space and time. While adequate, good-quality raw material was available in the Central Rhineland, the regular use of exogenous raw materials at Central Rhineland sites also demonstrates the necessity of maintaining regular social contacts with other groups in neighbouring regions.     

Size prediction in archaeomalacology: the Common Mussel,Mytilus edulis L., as an example

There are numerous size prediction formulae in archaeomalacology but (like almost all zooarchaeological formulae) only a few account for allometric growth (shape change with size change, which is almost universal in complex animals) and employ the standard methods developed by statisticians to ensure reliable predictions. A general technique for generating formulae that predict organism size from dimensions of their archaeological remains is presented, using an organism that is badly preserved archaeologically (the Common Mussel Mytilus edulis). Allometric growth is fully accommodated, and standard statistical methods and software are used. Several dimensions can be used for prediction, and poor predictors are identified and discarded. Predictions can be tested for consistency between heterogeneous conditions, for statistical soundness, and whether prediction errors are within tolerable limits.     

Adjustment or renewal in regional clusters? A study of diversification amongst SMEs in the Aberdeen oil complex

A renewed interest in the spatial clustering or agglomeration of economic activity is evident within economic geography and related fields. This paper considers processes of change within 'mature' regional clusters, developing a conceptual framework which links firm-level strategies to development scenarios at the cluster level through a set of intervening mechanisms. Whange, enabling the cluster to sustain its prosperity, and adjustment which is associated with stagnation and gradual decline. This conceptual framework is applied to an analysis of one key mechanism of change, diversification, as pursued by small and medium-sized enterprises (SMEs) in the Aberdeen oil cluster. Our analysis indicates that some diversification is occurring, with the implications for the cluster lying midway between adjustment and renewal. In conclusion, we emphasize the need to assess and 'unpack' the clusters concept and suggest that research should focus on the relationships between proximity, learning and evolution.     

A Comparison of Holocene and Historical Channel Change along the Macdonald River,Australia

Changes in channel morphology that occurred along the Macdonald River between 1949 and 1955 are often cited as an example of catastrophic channel change. However, the question of whether these changes represented one component of a cyclical evolutionary pattern, or a systematic and persistent shift to a new morphologic state remains to be clearly defined, as does the significance of these dramatic channel changes when viewed against the river's longer‐term Holocene history. In this paper, new measurements of the Macdonald River's channel morphology are used to resolve the river's evolution in the ～50 years since these major channel‐altering floods. By 2002, the Macdonald River's bed had narrowed considerably from its 1955 post‐flood maximum due to the construction of a new floodplain surface within the widened channel. In some locations, the 2002 bed width is comparable to that of the pre‐1949 channel. This aspect of the river's evolution follows models of cyclical channel evolution proposed for the region. However, in light of recent research into the river's longer term Holocene evolution, it is clear that other channel changes that occurred in response to the 1949–1955 floods, particularly the 2 metres of river bed aggradation and 7 kilometres down‐valley shift in the thalweg's intersection with mean sea level, are less cyclic in nature. The capacity of coastal rivers to prograde into estuaries, which in turn induces river bed aggradation, can be seen in this case to counteract the incisional tendencies associated with post‐flood channel contraction, such that persistent river bed aggradation occurs.     

The Sustainable Development of Kuwaiti Sabkhas

“Sabkha” is an Arabic term commonly used in foreign languages to denote a salt flat, a shallow depression. Sabkhas normally occur near sea level or at the underground water level. They usually are encrusted with a salt crust layer, the thickness of which depends on the location of the sabkhas and the evaporation rate. Sabkhas are one of the prominent surface topographical features in the Kuwaiti coastal zone, occupying an area of about 769.4 km², equivalent to 4.3 percent of the nation's total area. Due to their presence in the most important locations near the coastline, they are a most suitable setting for exploitative human activities. Sabkhas have attracted development proponents, particularly after the increased economic growth, and urgent need for homes and housing facilities. The most significant developments in the sabkha lands are urban development, agricultural forestation, and nature reserves. This study has revealed that there are environmental hazards related to the use of sabkha lands, including salt weathering, soil salinization, tree damage and depletion of natural reserves, the deterioration of nebakha (formation and growth around plants in the desert where groundwater is available for vegetation; the usual dune forms that occur in such instances are isolated mounds around individual plants) fields, and semikarstic (an area of irregular limestone in which erosion has produced fissures, sinkholes, underground streams, and caverns) solution holes. Therefore, use of such lands should take into account scientific investigation and selection among the different development fields. Such a fragile environment obliges us to consider nature conservation, a non‐disruption or depletion of sabkhas' limited natural resources, and their environmental components. The concept of the sustainable development should prevail in the use of such sabkhas.     

Air Services at Australian Cities: Change and Inertia 2005–2010

This research analyses international and domestic air services in Australia during a six year period, 2005–2010. We place air services into their urban context by relating them to city‐based measures such as population, tourism, and producer services employment among other measures. The research takes a supply‐side approach in an assessment of international and domestic capacity at major Australian airports from the perspective of the number of seats, the nature of links, and competition. Multiple linkage analysis and the concept of effective competitors allow us to explore this perspective at greater depth. Our findings show substantial changes in international patterns, specifically favouring Melbourne, Perth, and Gold Coast. In contrast, the domestic scene is characterised by little change, an outcome we link to the underlying stability in the settlement system and the location of some major economic activities. While the results are related to our measures of urban characteristics, some special region‐specific aspects are also at work. Finally, in both the international and domestic cases we find evidence of greater airline diversity which may benefit consumers.     

Where East meets West: The German—polish border region in transformation

There is growing interest in the German‐Polish border area's future status in the changing regional structure of Europe—contrasting scenarios contain, on the one hand, a vision of the region as a new ‘tiger’ region, and are seen at the other extreme as a ‘drainage area’ on the outskirts of the EU. In this article, border areas are treated from a point of view that pays more attention to the regions’ system of production and regulation. The first part deals with some general characteristics of border areas; the second part outlines in more detail the specific developmental conditions of the German‐Polish border area, especially the region between Berlin and Poznan along the middle part of the River Oder (comprising the Euro Region Pro Europa Viadrina). Three aspects of the border region's developmental conditions are emphasized: the region's quality of location within Europe and the respective national territories; the permeability of the border; and the economic structure in the border area, whereby forms of trans‐border economic linkage and cooperation are of particular interest. The last section discusses new challenges for European border areas as posed by economic change and the restructuring of the European spatial fabric.     

“西南”区域地理概念及范围的历史演变

"西南"区域地理概念及范围经历了长期的发展演变历程。先秦时期的"西南"主要包括巴和蜀。汉晋时期,"西南"区域概念正式确立,包括巴蜀和西南夷地区。唐宋时期,狭义的西南是指唐、宋王朝疆域内的西南地区,即唐代的剑南道、山南西道、黔中道,宋代的川峡四路;广义的西南还包括疆域外的南诏(大理)以及其它一些民族和王国。明清时期疆域内的"西南"出现了三种主要观点,较之前代范围有所扩大。近现代的"西南"概念发生了重大变化,只包括国家疆域内的西南各地。"西南"概念及范围受地理方位、地理环境、行政区划等因素的影响,具有动态性、模糊性、相对稳定性等特征,还有民族、边疆、政区、经济等多重含义。     

Contemporary Social Change as the Context for Geographical Enquiry: Towards a Reinvigoration of the Concept of Place

The nature of contemporary social change is explored by posing questions about the implications of neoliberalism, the character of leisure, the perils of materialism, and the shift from consumption to consumerism. Momentum is a powerful force in human affairs. Investigating its nature illustrates how the concept of equilibrium has been given undue emphasis in models of human behaviour. Momentum encourages ‘more of the same’ and is implicated in the way people fail to use leisure fully or effectively and in the way they subscribe to an emphasis on materialism and consumption as a path to happiness. Geography needs to engage with popular social scientific writing if it is to have a place in public intellectual debate. In many ways contemporary social change promises a reinvigoration of the concept of place and therefore challenges to both the substance and nature of geographical inquiry.