The need for river management and stream restoration practices to integrate hydrogeomorphology

There is growing support amongst scientists worldwide about the need for a shift in river management approaches to include hydrogeomorphic processes. However, the degree to which these concepts are transferred to governmental agencies and practitioners varies widely. In Quebec, for example, many stream restoration projects are based on the (incorrect) assumption that river mobility and its inevitable consequences (bank erosion of meanders, presence of woody debris in the channel) are problematic for salmonids. This paper presents examples drawn from current guidelines on stream restoration for fish habitat in Quebec to demonstrate the need to improve the knowledge exchange among scientists and decision makers about the positive impact of river mobility and large wood dynamics on biodiversity. Our observations reveal that existing guidelines for stream restoration in Quebec need to be revised to better integrate hydrogeomorphic concepts and to no longer assume that maintaining rivers in a static state is beneficial for fish. Adopting the “freedom space for rivers” approach would likely result in improved habitat as it combines natural processes related to mobility, flooding, and riparian wetland connectivity to determine the minimal space around rivers where development should not be allowed, thus allowing river processes to be restored.     

Integrating Geomorphological Assessments and Oral Histories in Catchment Management: Implications for the Mulgrave River,Northeastern Australia

The dramatic decline in the integrity of Australian river systems in recent decades has seen the development of landcare and catchment management groups across the continent as the main facilitators of river rehabilitation works. There is growing concern for the need to develop adaptive management frameworks that assist informed decision making through the integration of social and geomorphological knowledge into catchment planning. In the Mulgrave River Catchment of northeastern Queensland, difficult management decisions have to be made with limited access to knowledge of natural processes and baseline geomorphological data. To date management decisions have been based almost exclusively on oral histories that state that point bars are accreting and the river is becoming shallower due to bank erosion. As a result bank stabilisation and removal of sand from within the channel have been recommended in the absence of any geomorphological assessments. This study compares oral histories of river bank erosion in the Mulgrave River with geomorphic evidence to highlight the need for integrated landscape scenario planning. The results of grain size analysis of bank and bed material from 27 locations, involving 47 samples, suggest that bank erosion cannot be delivering sediments to point bars. Furthermore, qualitative analysis of historic parish maps and aerial photographs shows that there has only been moderate bank erosion at three locations along the Mulgrave River since European settlement. The study demonstrates the important role that geomorphological investigations have for catchment management and the need for management frameworks that integrate geomorphological processes and landholder priorities for sustainable river management.     

The Impact of Large Water Engineering Projects on Geomorphic Processes in Stream Valleys

Large storage reservoirs have a significant effect on the landscape of river valleys. A rise of the base level, caused by dam construction, together with the resulting changes in the stream regime set off a sequence of interrelated geomorphic processes. Upstream from the edge of the backwater produced by the dam, regressive aggradation gradually spreads upriver, resulting both in a rise in the valley floor and a rise in water level. Within the reservoir itself, waves, longshore currents, seasonal changes in water level and gravitational processes on shoreline slopes combine to produce a distinctive shoreline relief, characterized by large areas of recurrent inundation, lagoon closed off by baymouth bars, and high cliffs retreating under the impact of wave abrasion. Downstream from the dam, heavy downcutting of the river channel gives rise to a stream terrace, whose relative height declines from the vicinity of the dam toward the mouth. Downcutting of the channel in the main stream in turn tends to lower the base level in the lower reaches of tributaries.     

Streams as Entanglement of Nature and Culture: European Upper Paleolithic River Systems and Their Role as Features of Spatial Organization

Large river valleys have long been seen as important factors to shape the mobility, communication, and exchange of Pleistocene hunter-gatherers. However, rivers have been debated as either natural entities people adapt and react to or as cultural and meaningful entities people experience and interpret in different ways. Here, we attempt to integrate both perspectives. Building on theoretical work from various disciplines, we discuss the relationship between biophysical river properties and sociocultural river semantics and suggest that understanding a river’s persona is central to evaluating its role in spatial organization. By reviewing the literature and analyzing European Upper Paleolithic site distribution and raw material transfer patterns in relation to river catchments, we show that the role of prominent rivers varies considerably over time. Both ecological and cultural factors are crucial to explaining these patterns. Whereas the Earlier Upper Paleolithic record displays a general tendency toward conceiving rivers as mobility guidelines, the spatial consolidation process after the colonization of the European mainland is paralleled by a trend of conceptualizing river regimes as frontiers, separating archaeological entities, regional groups, or local networks. The Late Upper Paleolithic Magdalenian, however, is characterized again by a role of rivers as mobility and communication vectors. Tracing changing patterns in the role of certain river regimes through time thus contributes to our growing knowledge of human spatial behavior and helps to improve our understanding of dynamic and mutually informed human-environment interactions in the Paleolithic.     

Assessment of Riparian Rainforest Vegetation Change in Tropical North Queensland for Management and Restoration Purposes

Changes in riparian vegetation extent in northern Queensland, Australia were assessed using aerial photographs from 1944 and 2000. Change in riparian extent was recorded as vegetation gain or loss. Changes in density were recorded as vegetation thickening. Riparian forest coverage increased by 22 ha during this time period in the Mossman River catchment. A total of 124 ha of riparian forest were gained, while 101 ha of riparian forest were lost. A further 59 ha of forest increased in density over this time period. Clearing, changes in farm management practices and natural stream channel movement have been identified as three potential causes for these changes. Areas with little or no riparian vegetation were identified and categorised into priority levels for potential revegetation efforts.     

Landform Conservation and Flood Control: the Issue of the Chitose Diversion Channel Project in Hokkaido,Japan

Landform conservation is the main task of geomorphology in the 21st Century. Since landforms provide the templates for the development of wildlife habitats, landform change is likely to cause habitat loss, inducing a reduction of biodiversity. From the viewpoint of ‘geomorphic species’, specific landforms such as natural rivers, tidal flats and coral reefs are endangered species in the Japanese islands. To avoid the further destruction of natural rivers, environmentally appropriate flood control plans are necessary. The analysis of the Chitose Diversion Channel project in Hokkaido, Japan, revealed that (1) the construction of this diversion channel has caused not only environmental problems but also serious social conflicts relating to habitats within and beyond the drainage basin; (2) excavation of a deep channel changed the groundwater supply which previously supported a natural river system, and (3) selection of a very high discharge value as the target of flood control was the main reason for planning this project. From a landform conservation perspective, the method adopted in Japan is unsuitable because it does not incorporate the scientific procedure necessary for selecting the ‘best’ peak discharge corresponding to the target rainfall with a certain recurrence period. An alternative flood control plan, combining the selection of a lower peak discharge, construction of retention pools and the restoration of meandering river channels is proposed to avoid the further destruction of natural rivers.     

Justice in River Management: Community Perceptions from the Hunter Valley,New South Wales,Australia

Dealing with differing and sometimes conflicting criteria for priority‐setting is an essential part of sustainable natural resource management. However, all too often, these ethical and political considerations are neglected within a planning regime based upon apparently ‘objective’ biophysical assessment techniques. Input into associated decision‐making processes is also frequently restricted to a narrow range of ‘stakes’ based upon historical and geographic circumstances. This paper reports on the findings of interviews and discussion groups in the Hunter Valley, New South Wales, which aimed to canvass the diversity of perceptions of distributive and procedural justice in river rehabilitation. A range of biophysical and social criteria for setting priorities in rehabilitation work was identified. Participants also had differing ideas on the composition of decision‐making bodies and on decision‐making processes. The key implications of these findings are that sustainable river management policy needs to openly address differing conceptions of justice and that rehabilitation practice should be holistic, transdisciplinary and concerned with both outcome and process.     

Assessment of Riparian Revegetation Trials on In-Channel Benches in the Hunter Valley of Southeast Australia

Large-scale river training works have been carried out in the Hunter valley since 1955 in response to flood-driven channel changes. Vegetation was planted on in-channel benches induced by river training works to consolidate the deposits and to increase channel boundary roughness. Exotic species of vegetation such as willows and poplars were previously used. In 1983, ten trial sites were planted with various species of native vegetation. Survival rates were evaluated in 1987 and 1997. The most successful species planted was Eucalyptus camaldulensis with an overall survival rate of 77 per cent in 1997. The Acacia species were found to be short-lived, exhibiting a significant decline in survival rates between 1987 and 1997. Survival rates for most species were higher on sand-bed than on gravel-bed sites. This difference may be attributed to better drainage on benches at the sand-bed sites. Investigations of flood disturbance showed that between 1983 and 1997 the sites were flooded between four and 13 times. The survival rates of Grevillea robusta and Eucalyptus melliodora trees were negatively correlated with the total number of recorded floods at each site. Poor natural regeneration of planted species is attributed to a combination of periodic flooding, intensive weed growth, low light intensities at ground level and grazing disturbance. These trials were not well designed for statistical analysis but provide valuable long-term information on the suitability of various species for planting in riparian rehabilitation programs. Such information is of relevance not only to river and catchment management authorities, but also to community groups.     

The Changing Value of Australian Tropical Rivers

Until recently the objectives of tropical river management were narrowly construed: the development imperative drove resource policy. During recent decades, community attitudes to river and water management have changed considerably and the national program of water reform, the National Water Initiative, is accelerating alterations to the way that water is used, managed and priced. A broader range of values and imperatives is now influencing water resource management policy. Not least is the concern over the ecological impacts and economic inefficiencies of the large‐scale hydrological schemes that once excited the public's imagination. This paper reports on a recent study of social and economic values of tropical rivers conducted by the authors for an Australian statutory research and development corporation. The study shows that the values associated with tropical rivers have changed and diversified over time with growing societal awareness of the contribution made by unregulated, healthy river systems to human wellbeing and cultural identity. As a consequence of substantial social change, tropical river management must now contend with a more complex array of societal values and water management objectives.     

Securing Landscape Resilience to Tropical Cyclones in Australia's Wet Tropics under a Changing Climate: Lessons from Cyclones Larry (and Yasi)

Tropical cyclones are part of the ecosystem dynamics of rainforests in the Wet Tropics of Australia, and intact forest areas show remarkable ability to recover from cyclonic disturbance. However, forest remnants, littoral rainforests, and riparian vegetation have been shown to be particularly susceptible to cyclonic winds and post‐disturbance weed invasion with consequences for their long‐term conservation values. I evaluate the frequency and intensity of tropical cyclones impacting the Wet Tropics region since records began in 1858. The recent Category 4 cyclones featured in this study, Larry and Yasi, had return intervals of about one in 70 years. I then discuss the natural resource management (NRM) lessons from Cyclone Larry and put forward practical recommendations on how authorities should deal with natural resources in the clean‐up and recovery phases. I argue that natural resources must be treated as valuable commodities by including their protection and rehabilitation in the same way that human livelihoods, infrastructure and industry are covered in disaster management planning. This requires NRM issues to be included in disaster response policy and legislation, together with ensuring that structures are in place to mitigate the effects of cyclones on natural resources. There is a general consensus that tropical cyclone intensity will increase under climate change while frequency will decrease slightly. This has profound implications for the long‐term sustainability of ecosystems in the Wet Tropics. There is a real risk of a phase shift to vegetation types dominated by disturbance species, including weeds, at the expense of cyclone intolerant species. It is therefore important that we begin to build more cyclone resilient landscapes to reduce the vulnerability of our remaining rainforest habitats and primary production systems. Securing landscape resilience requires greater NRM investment in key areas, including landscape connectivity, river repair, protecting coastal assets and cyclone resilient farms. While climate change poses a long‐term threat to the rainforests of the region, we need to focus on more immediate pressures affecting our remaining biodiversity, notably clearing of native habitat, habitat fragmentation and degradation, and biosecurity issues.     

International rivers as border infrastructures: En/forcing borders in South Asia

Rivers have long been convenient yet troublesome borders. Inherently itinerant, rivers routinely defy cartographic depictions of borders as static, territorially bounded formations. Such dynamism poses material and conceptual challenges to state regulatory activities, resulting in increasingly heterodox attempts to fix waterbodies through various securitizing mechanisms. I examine the dialectical relationship between rivers and borders through the concept of the river-border complex. I ask how the Ganges River shapes the form and function of the Indo-Bangladeshi border and how, in turn, bordering practices in India regulate flows along the river, which comprises 129 km of India's border with Bangladesh. Drawing on archival records, in-person interviews, and river data, I find that the border and efforts to secure it mediate many flows along the river. The study corroborates previous work within critical border studies that securitizing cross-border flows has the perverse effect of generating greater insecurity in adjoining countries. Crucially, historical analysis of sediment, information, and human flows reveals how international rivers also determine patterns and processes of circulation and thereby warrant reconceptualization as border infrastructures, rather than as merely being subject to them.     

The Danube‐Rhine water system as a European regional integration structure

This article explores the role of two large European rivers — the Rhine and the Danube — in the structured development of the European territorial system. The water resources of the Rhine river, the tributaries and connecting canals have created the greatest industrial megalopolis on the continent. In this process and under contemporary conditions, the area is connected with the Danube basin by the newly built Rhine‐Main‐Danube canal. As a result, new structures are forming, having the character of an ecological‐economic system. It is in this direction that part of the European territorial system connected with the Danube is developing. As physical‐geographical and ecological factors accelerate economic development and integrate new economic structures, new opportunities arise. With the link to ecological and water resources, development of the Danube as Europe's newest, prospective zone of expansion is predicted.     

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.     

A River Runs Through It: Morphological and Landowner Sensitivities Along the Upper Missouri River, Montana, USA

Landowners along the Missouri River in Montana believe that the operation of Fort Peck Dam has initiated bank erosion, thus threatening agricultural development within the region. Their concerns have been heightened by proposals to increase discharge in order to enhance fisheries and wildlife interests. Geomorphological evaluation indicates that bed degradation and bank erosion have declined since construction of the dam, and the channel is now approaching dynamic equilibrium; public sensitivity to the proposed change is greater than the morphological sensitivity of the river. Sustainable management of the Missouri is now based on strategies that place more emphasis on partnership with local citizens.     

Do We Really Understand Our Rivers? or Rivers in the Pooh - Semper in Excreta!

This address is concerned with the lack of detailed understanding we have of rivers. It is argued that to manage river systems for environ- mental and ecological sustainability, there must be understanding of riverine biophysical processes. These are explored through a consideration of: (1) channel airspace and water; (2) the perimeter conditions of the channel as the boundary between erosional channel and depositional floodplain, both of which occupy the valley-floor trough; (3) ecological components of channels and (4) the human components where human interactions with catchment environments have such impacts on the biophysical systems. Finally, the implications of these four components for understanding the systems for more sustainable management are discussed.     

River metamorphosis and environmental change in the Macdonald Valley,New South Wales,since 1949

A significant metamorphosis of channel form occurred on the lower Macdonald River between 1949 and 1955; width and width-depth ratio increased and depth, sinuosity and weighted mean per cent silt-clay in the channel perimeter decreased. The channel has remained unstable since 1955, exhibiting frequent variations in bed elevation and a recent period of minor channel contraction followed by slight enlargement. Since 1946 there has been an increase in summer and annual rainfall and an abrupt, upward shift of the annual series flood frequency curve. As a result an increased proportion of the total sediment load of the river is now being transported as bed-material load. The change in sediment load is a result of greater stream competence and the consequent reworking of sandy sediment temporarily stored within the channel as benches. The observed channel changes are a quasi-adjustment to the increased flood and bed-material load discharges.     

关中东部河道变迁对自然环境的影响

关中东部为黄渭洛交汇区 ,历史时期黄渭洛河道的变迁对这一带自然环境的影响重大 ,不但使三河河谷展宽 ,沙洲沙地增多 ,而且使泥沙淤积 ,河床抬高 ,两岸滩地兴废频繁 ;同时还使支流入河口不断发生变化 ,特别是对关中沙苑特殊地形的形成提供了泥沙。     

湖北十堰潘口水电站三处古遗址的发掘

潘口水电站与陕南和川东接壤,是古庸国所在地.遗址地处河流边缘地带,长年受河水的冲刷,破坏殆尽,出土遗物甚少,文化内涵主要包含新石器晚期和东周时期遗存.东周时期文化面貌较为复杂,既有楚文化特征又具巴蜀文化风格,同时还包含陕南文化因素,这种多元文化因素,是与周边文化相互影响、碰撞形成的一种以地方文化为特色的多元文化.因此,我们认为潘口水电站淹没区的小府坪、红花湾、王家套等遗址是东周时期楚灭庸后的一处村落遗址.     

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.     

Age and sedimentological features of fluvial series in the Toruń Basin and the Drwęca Valley (Poland)

The deposits of the Toruń Basin are dominated by a few-metre thick sand series which fill up buried valley-like depressions. In many cases they underlie the Weichselian till which builds up the ice marginal streamway (pradolina) terraces or they are exposed at the basin slopes. As the results of the geological and sedimentological studies, as well as of the dating of the deposits at the sites in the Toruń Basin indicate, the deposits include two fluvial series accumulated before the advancement of the Leszno Phase ice sheet, i.e. in Middle Weichselian and at the beginning of Late Weichselian. The oldest fluvial series connected with the Saalian Glaciation was found at the mouth section of the Drwęca Valley. The fluvial system of the Toruń Basin during Middle Weichselian and at the beginning of Late Weichselian developed in two phases of the sand-bed braided river. During the first one the river channel were dominated by large mid-riverbed sandbars, while during the second phase the water flow was smaller and, as a result, low transverse sandbars and two-dimensional dunes developed. Other active river channel also showed low-energy flows, more intensive meandering than in the case of the braided rivers, as well as sandy side-bars. Analysis of the rounding and frosting of the quartz grains indicate that the studied series of the Weichselian sandy deposits represent alluvia of a river which were fed from two diverse sources. The first one might have represented the alluvia of a warm river which transformed its load, while the other one might have mainly carried the underlying Quaternary deposits.