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Aim Immune checkpoint inhibition (ICI) triggers immune-related adverse events (irAEs). The relevance of lipase elevation remains unclear. Patients and methods Skin cancer patients with newly detected serum lipase elevation (at least twofold upper normal limit) or newly diagnosed type I diabetes mellitus upon ICI therapy were retrospectively collected at 14 German skin cancer centres. Results We identified 68 patients with lipase elevation occurring after a median time of 19 (range 1–181) weeks on ICI, 15 (22%) thereof had symptoms consistent with pancreatitis. Forty-seven patients (73%) had other irAE, mainly colitis. Discontinuation (n = 24, 35%) or interruption (n = 26, 38%) of ICI resulted in decrease of lipase after reinduction of ICI lipase levels increased again in 12 of 24 patients. In 18 patients (27%), ICI was continued unchanged, and in 12 (67%) of them, lipase levels normalised. Twenty-two patients were identified with newly diagnosed type I diabetes mellitus related to ICI, and 12 (55%) thereof had also lipase elevation mainly shortly before or after the diagnosis of diabetes. Fourteen (64%) patients had other irAE, mainly thyroiditis. Irrespective of lipase elevation, patients frequently showed a rapid onset with ketoacidosis, decreased c-peptide, and strongly increased blood glucose levels. Conclusion Increased serum lipase during ICI is often not associated with pancreatitis but with other irAE as possible cause. Therefore, it might be sufficient to regularly monitor blood glucose levels and perform further workup only in case of signs or symptoms of pancreatitis and/or exocrine pancreas insufficiency.

Background Cutaneous squamous cell carcinoma (cSCC) is one of the most common malignancies of the skin. Even though most patients are sufficiently treated by surgical resection, some will eventually metastasize and need systemic therapy. Phase I and II studies have shown efficacy for programmed cell death protein 1 (PD-1) inhibitors, but cohort sizes are low and real-world data especially on long-term outcome are pending. Methods Patients from six German skin cancer centers treated with PD-1 inhibitors (pembrolizumab, nivolumab or cemiplimab) for advanced cSCC were retrospectively studied. Internal patient records were analyzed for clinical outcome including response, progression-free survival (PFS), overall survival (OS) and toxicity. Results Of 46 evaluable patients (median age: 76 years), the overall response rate (RR) was 58.7%, including 15.2% with complete response. The disease control rate was 80.4%. Both median PFS and OS were not reached, Kaplan–Meier estimated 1-year PFS was 58.8%. Patients responding to therapy showed durable remission. Response was independent of the PD-1 inhibitor used and also independent of the presence of distant metastases vs. locally advanced disease. Two predictive factors were found: Patients with primaries located on the leg had a poorer therapy outcome and patients with high lactate dehydrogenase serum levels at baseline. Treatment was overall tolerated well, with less than 10% of patients discontinuing therapy due to toxicity. Conclusions PD-1 inhibitors fulfill the need for an efficient systemic therapy for advanced cSCC and should be the new standard of care. With high RRs and durable disease control, neoadjuvant and adjuvant regimens should be evaluated.

Geomorphology plays a fundamental role in shaping and maintaining landscapes, as well as influencing the social and ecological systems that occupy and utilize these landscapes. In turn, social-ecological systems can have a profound influence on geomorphic forms and processes. These interactions highlight the tightly coupled nature of geomorphic systems. Over the past decade, there has been a proliferation of research at the interface of geomorphology and resilience thinking, and the 2017 Binghamton Symposium brought together leading researchers from both communities to address mutual concerns and challenges of these two disciplines. This paper reviews some of the key intersections between the disciplines of bio-geomorphology and resilience thinking, and the papers presented at the symposium. The papers in this volume illustrate the current status of the disciplines, the difficulties in bridging the disciplines, and the issues that are emerging as research priorities.

The concept of resilience acknowledges the ability of societies to live and develop with dynamic environments. Given the recognition of the need to prepare for anticipated and unanticipated shocks, applications of resilience are increasing as the guiding principle of public policy and programs in areas such as disaster management, urban planning, natural resource management, and climate change adaptation. River science is an area in which the adoption of resilience is increasing, leading to the proposition that resilience may become a guiding principle of river policy and programs. Debate about the role of resilience in rivers is part of the scientific method, but disciplinary disunity about the ways to approach resilience application in policy and programs may leave river science out of the policy process. We propose six elements that need to be considered in the design and implementation of resilience-based river policy and programs: rivers as social-ecological systems; the science-policy interface; principles, capacities, and characteristics of resilience; cogeneration of knowledge; adaptive management; and the state of the science of resilience.

Our understanding of the effectiveness of reintroduced large wood for restoration is largely based on studies from high energy river systems. By contrast, few studies of the effectiveness of reintroducing large wood have been undertaken on large, low energy, lowland river systems: river systems where large wood is a significant physical feature on the in-channel environment. This study investigated the effect of reintroduced large wood on the hydraulic landscape of the Barwon-Darling River, Australia, at low flows. To achieve this, the study compared three hydraulic landscapes of replicated reference (naturally wooded), control (unwooded,) and managed (wood reintroduced) treatments on three low flow periods. These time periods were prior to the reintroduction of large wood to managed reaches; several months after the reintroduction of large wood into the managed reaches; and then more than four years after wood reintroduction following several large flood events. Hydraulic landscapes of reaches were characterised using a range of spatial measures calculated from velocity measurements taken with a boat-mounted Acoustic Doppler Profiler. We hypothesised that reintroduced large wood would increase the diversity of the hydraulic landscape at low flows and that managed reaches would be more similar to the reference reaches. Our results suggest that the reintroduction of large wood did not significantly change the character of the hydraulic landscape at the reach scale after several months (p = 0.16) or several years (p = 0.29). Overall, the character of the hydraulic landscape in the managed reaches was more similar to the hydraulic landscape of the control reaches than the hydraulic landscape of the reference reaches, at low flows. Some variability in the hydraulic landscapes was detected over time, and this may reflect reworking of riverbed sediments and sensitivity to variation in discharge. The lack of a response in the low flow hydraulic landscape to the reintroduction of large wood is inferred because the character (the size and complexity of individual pieces) and positioning of large wood in managed reaches did not mimic that of reference reaches effectively despite the abundance of wood pieces being similar in the reference and managed reaches. The results of this study highlight the importance of understanding the natural character and distribution of large wood on hydraulic landscapes in large low energy lowland river systems, especially when reintroducing large wood for river management purposes.

The geomorphological character of a river network provides the template upon which evolution acts to create unique biological communities. Deciphering commonly observed patterns and processes within riverine landscapes resulting from the interplay between physical and biological components is a central tenet for the interdisciplinary field of river science. Relationships between the physical heterogeneity and food web character of functional process zones (FPZs) – large tracts of river with a similar geomorphic character –in the Kanawha River (West Virginia, USA) are examined in this study. Food web character was measured as food chain length (FCL), which reflects ecological community structure and ecosystem function. Our results show that the same basal resources were present throughout the Kanawha River but that their assimilation into the aquatic food web by primary consumers differed between FPZs. Differences in the trophic position of higher consumers (fish) were also recorded between FPZs. Overall, the morphological heterogeneity and heterogeneity of the river bed sediment of FPZs were significantly correlated with FCL. Specifically, FCL increases with greater FPZ physical heterogeneity. The result of this study does not support the current paradigm that ecosystem size is the primary determinant of food web character in river ecosystems.

Dryland floodplains are characterized by highly variable flooding and drying. This variability plays a key role in the productivity of dryland floodplain vegetation. The Normalized Difference Vegetation Index, a surrogate for vegetation productivity, has been extensively used to examine floodplain vegetation productivity responses to flood inundation but generally focuses on inundation alone, or at a single scale thereby potentially omitting important elements of dryland variability. This study used fine resolution satellite imagery, through sequences of flood and dry resource states, at multiple scales of observation and with consideration of the relative influence of rainfall and flow to examine floodplain vegetation productivity in the dryland floodplain. There were marked differences in floodplain vegetation productivity between wet and dry resource states. Overall, response patterns were complex and varied among vegetation communities and in different resource states. The findings suggest that vegetation productivity in the Narran floodplain does not correspond well with the boom and bust model of floodplain ecosystem productivity. Rather, understanding vegetation productivity in a highly variable floodplain requires an enhanced understanding of the nature of variability in space and time. Conceptual models that can better convey the complexity of vegetation productivity responses to floodplain wetting and drying are suggested.

Fish growth in river ecosystems is influenced by a multitude of environmental drivers, including the heterogeneity of these drivers. Globally, river ecosystems are subject to anthropogenic stressors that can simplify riverine landscapes, homogenize riverine communities, and favor nonnative fishes. Yet, how anthropogenically driven simplification of riverine landscapes affects fish life-history traits remains largely unknown. The aim of this study was to examine the character of fish growth along the entire main channel of an Anthropocene River. We collected four species of potamodromous fish from different functional feeding guilds, from each of six functional process zones (FPZs) – unique large-scale hydrogeomorphic patches – along the entire length of the Illinois River (Illinois, USA), and calculated three growth metrics: growth rate (k), maximum size (L∞), and a relative growth index. The majority (7 of 12) of species-growth metric combinations did not differ among FPZs. Of the five species-growth metric combinations that were different, none exhibited more than three distinct groups of values. The limited difference in growth along the main channel of the Illinois River reflects a homogenization of ecosystem function, and is associated with the systemic simplification of physical heterogeneity of the river channel. The fishes studied from the Illinois River also tended to have faster growth rates (k) and smaller maximum sizes (L∞) relative to other North American freshwater ecosystems. Our results reveal spatial constraints to life-history traits and changes to ecosystem interactions, which are evidence of being in a new regime or state. This has implications for the reproductive output and resilience of native fishes in Anthropocene Rivers.

Physical heterogeneity is a strong driver of ecosystem function in rivers, but it is not clear whether this relationship persists in “Anthropocene” rivers: those affected by pronounced and persistent anthropogenic stressors. Such stressors can result in regime shifts of rivers, altering not only ecosystem structure and function, but also their heterogeneity. This study examines the heterogeneity of the physical template and ecosystem function of the Illinois River (Illinois, USA), as an example of an Anthropocene River. This river was biologically dead for most of its length in the mid 1900′s because of multiple anthropogenic stressors. A systemic reduction in physical heterogeneity of the Illinois River also resulted in simplification of its physical environment. Multiple lines of evidence demonstrate the physical simplification of the river channel caused the homogenization of ecosystem function. The significant overlap in trophic niche spaces, convergence of isotope ratios, dominance of benthic contributions to higher-level consumers, increased food chain lengths, plus the emergence of only two food webs indicate a simpler river ecosystem. Limited attention to the role of heterogeneity in anthropogenically modified river systems not only restricts understanding of resilience in rivers, but also the application of resilience thinking to managing these globally important ecosystems.

Many studies of fluvial geomorphology and landscape ecology examine a single river or landscape, thus lack generality, making it difficult to develop a general understanding of the linkages between landscape patterns and larger-scale driving variables. We examined the spatial complexity of eight floodplain surfaces in widely different geographic settings and determined how patterns measured at different scales relate to different environmental drivers. Floodplain surface complexity is defined as having highly variable surface conditions that are also highly organised in space. These two components of floodplain surface complexity were measured across multiple sampling scales from LiDAR-derived DEMs. The surface character and variability of each floodplain were measured using four surface metrics; namely, standard deviation, skewness, coefficient of variation, and standard deviation of curvature from a series of moving window analyses ranging from 50 to 1000 m in radius. The spatial organisation of each floodplain surface was measured using spatial correlograms of the four surface metrics. Surface character, variability, and spatial organisation differed among the eight floodplains; and random, fragmented, highly patchy, and simple gradient spatial patterns were exhibited, depending upon the metric and window size. Differences in surface character and variability among the floodplains became statistically stronger with increasing sampling scale (window size), as did their associations with environmental variables. Sediment yield was consistently associated with differences in surface character and variability, as were flow discharge and variability at smaller sampling scales. Floodplain width was associated with differences in the spatial organisation of surface conditions at smaller sampling scales, while valley slope was weakly associated with differences in spatial organisation at larger scales. A comparison of floodplain landscape patterns measured at different scales would improve our understanding of the role that different environmental variables play at different scales and in different geomorphic settings.

Interactions between fluvial processes and floodplain ecosystems occur upon a floodplain surface that is often physically complex. Spatial patterns in floodplain topography have only recently been quantified over multiple scales, and discrepancies exist in how floodplain surfaces are perceived to be spatially organised. We measured spatial patterns in floodplain topography for pool 9 of the Upper Mississippi River, USA, using moving window analyses of eight surface metrics applied to a 1 × 1 m 2 DEM over multiple scales. The metrics used were Range , SD , Skewness , Kurtosis , CV , SD CURV , Rugosity , and Vol:Area , and window sizes ranged from 10 to 1000 m in radius. Surface metric values were highly variable across the floodplain and revealed a high degree of spatial organisation in floodplain topography. Moran's I correlograms fit to the landscape of each metric at each window size revealed that patchiness existed at nearly all window sizes, but the strength and scale of patchiness changed within window size, suggesting that multiple scales of patchiness and patch structure exist in the topography of this floodplain. Scale thresholds in the spatial patterns were observed, particularly between the 50 and 100 m window sizes for all surface metrics and between the 500 and 750 m window sizes for most metrics. These threshold scales are ~ 15–20% and 150% of the main channel width (1–2% and 10–15% of the floodplain width), respectively. These thresholds may be related to structuring processes operating across distinct scale ranges. By coupling surface metrics, multi-scale analyses, and correlograms, quantifying floodplain topographic complexity is possible in ways that should assist in clarifying how floodplain ecosystems are structured.

article i nfo The field tradition in geomorphology informs beyond studying landforms by also providing a stage for understand- ing how geomorphic elements influence the ecology of biota. The intersection between fluvial geomorphology and riverine ecology represents an ideal confluence to examine the contribution of the geomorphic field tradition to en- vironmental flows, and show this area of riverine management as a research frontier for applied geomorphology. Environmental flows have consisted of a set of ecological-based stream flow guidelines designed to inform sustain- able water resource management that supports healthy riverine habitats and provides sufficient water supply for society. Geomorphological understanding is central to environmental flows because it is the interaction between flow, form, and substrate that influences habitat type, condition, availability and biotic use across space and time. This relationship varies longitudinally, laterally, vertically, overtime, and across macro- to mesoscale morphologies withintheriverine environment.Thegeomorphictemplateis,therefore,asintegralasthe flow. Wereviewedstudies where field evidence indicated that geomorphology impacts the effectiveness of environmental flow strategies and wemakethecasefortheneedtoincreasegeomorphic considerationsinenvironmental flows. Although flow iscom- monly referred toas themaster variablein environmental flows,geomorphologymediatestheeffectsof flow regime on ecological processes. Concepts and applications from this perspective on the role of geomorphology in riverine ecosystem research will inform the practice, policy, and implementation of environmental flows.

Background Nevus spilus (NS) defines a cafe-au-lait macule with superimposed maculopapular speckles. Although the cafe-au-lait macule often presents at birth, the darker pigmented speckles increase in number and size during a period of several years. The need for close follow-up of patients with NS is underlined by reports of several cases of cutaneous melanoma developing within such lesions. Methods We followed up 4 adult patients (3 male, one female; mean age 38 years) with unilateral segmental NS of the thoracic or abdominal region. The NS was present at birth in all 4 patients. Follow-up by sequential digital dermatoscopy and digital overview images was scheduled every 6 to 12 months. Results During surveillance (mean follow-up time, 8.15 years), 3 melanocytic lesions were excised. In one patient focal enlargement prompted excision of two dysplastic compound nevi. In another patient new black dots and focal peripheral hyperpigmentation were detected by comparison with previous images. Histologic analysis confirmed the diagnosis of invasive melanoma (Breslow thickness, 0.6 mm). Limitations This observational clinical study included a small number of patients. Sequential digital dermatoscopy of large NS in children may lead to unnecessary excisions because of physiologic changes. Conclusion We suggest close follow-up of patients with segmental NS whenever complete excision is not possible. In adults, follow-up by digital dermatoscopy and excision of lesions with dynamic changes may assist in the early detection of melanoma.

The interplay of biological and physical patterns and processes within river ecosystems generates a complex matrix of interactions. A challenge in interdisciplinary river science is to dissect patterns and processes in multi-causal river ecosystems into hierarchical levels of organization. Hierarchy theory, and the associated concept of scale, provides a sound framework for achieving this. We present two interdisciplinary case studies that demonstrate how a multi-scale approach can dissect hierarchies of organization in river ecosystems. The first case study examined patterns of large wood character and distribution at three scales of a hierarchy of morphological river system organization in the large, lowland River Murray. The character and distribution of large wood was uniform at the largest reach scale (95 km length of river) because stream energy conditions are relatively uniform within the reach. However, there was an association between lower-level functional sets (straight or bend sections of river) and functional units (12 quadrats within each functional set) and the character and distribution of large wood, because stream energy differs between straight and bend morphologies, and the inner- and outer-channel functional units. Thus, functional sets and functional units are important levels of organization for large wood in the River Murray. The second case study examined the associations between macroinvertebrate assemblage distribution and environmental influences across a hierarchy of river system organization in the upland Murrumbidgee River catchment. We previously demonstrated that macroinvertebrate assemblages were arranged hierarchically at the region, cluster within region, reach within cluster and riffle within reach scales, with region and reach being the strongest signatures. In this study we related different scaled environmental factors, collected across a hierarchy of catchment, zone (valley confinement), reach (similar stream orders) and riffle scales to the region and cluster levels of macroinvertebrate distribution. The hierarchical pattern of large, region-level and local, reach-level macroinvertebrate distribution was matched by a large catchment-scale and local reach-scale of environmental influence. Intermediate zone-scale environmental factors and smaller riffle-scale factors were not important influences. Thus, large regions and catchments and local reaches are important levels of organization for macroinvertebrate-environment associations in rivers of the upper Murrumbidgee catchment. Both case studies support the applicability of hierarchy theory to describe the organization of physical–biological associations in river ecosystems. The multi-scaled approach allowed the detection of levels of hierarchical organization, and showed other hierarchical characteristics such as emergent properties and top–down constraint/bottom–up influence. Hierarchical understanding of river ecosystem organization will enhance river conservation and management because it facilitates a holistic, ecosystem perspective rather than a partial, single-scale, single-component or single-discipline perspective.

Geomorphology plays a fundamental role in controlling many ecosystem processes, and in turn, ecosystems can have a profound influence on many geomorphic forms and processes. Over the past few decades, a proliferation of research has developed at the interface of geomorphology and ecosystems ecology. The 2005 Binghamton Symposium brought together some of the leading researchers from both communities to address these critical interfaces between the disciplines. This paper reviews some of the aspects of the disciplines of geomorphology and ecosystems ecology, and the papers presented at the symposium. The papers in this volume illustrate the current status of the disciplines, the difficulties in bridging the disciplines, and the issues that are emerging as research priorities.

1. Primary production on semiarid floodplains supports a diverse local and regional fauna. Reduced flooding from water resource development (WRD) may affect floodplain production by decreasing water and nutrient supply. 2. We investigated the effects of reduced wetting on soil fertility by performing a regional soil survey across a gradient of flood frequency. Soil nitrogen (N), phosphorus (P) and carbon (C) were recorded over a soil-wetting event where heavy rainfall and flooding coincided. 3. Soil nutrient concentrations indicate N limits plant growth and P does not. 4. No spatial patterns in soil P were detected across the floodplain, suggesting that the principal mechanism controlling P fertility is the concentration of P in floodplain source material, and that flood mediated import and export of P are minor processes. 5. Soil N concentrations rose following rainfall and flooding and the greatest increased occurred in flooded areas. Flood deposition of N accounted for only 9% of the boost in soil N in flooded areas, and N concentrations continued to rise when the floods and rains ceased. Elevated soil N levels do not appear to persist because at the start of a growth cycle, when soils were dry, soil N did not vary significantly with flood frequency. This suggests most of the boost in soil N was due to N-fixation, with the subsequent loss of N likely to have resulted from in situ processes such as denitrification. 6. Agricultural export of nutrients appears to not be a significant process in the context of the high phosphorus fertility of floodplain source material and the apparently high rates of in situ processing of nitrogen. 7. Synthesis and applications. Our data suggest that floodplain soil fertility is controlled by mechanisms other than flood frequency or agricultural export, meaning that WRD is unlikely to affect soil fertility; however, the biological implications of the brief pulse in soil N associated with wetting need further investigation.

Large rivers are often considered to retain less organic material than smaller streams primarily because of a decrease in retentive structures. From our observations on the Barwon–Darling River, a semi-arid river in southeastern Australia, we suggest that geomorphic complexity plays a fundamental role in the retention of organic matter. The Barwon–Darling River has a ‘complex’ river channel cross-section with large inset benches being a prominent morphological feature within the channel. The importance of geomorphic complexity for retaining organic material is likely to be significant in dryland rivers. These rivers spend extended periods at low flow with infrequent large floods that inundate the floodplain. They do, however, experience more frequent within channel floods that inundate in-channel ‘bench’ features. In-channel geomorphic complexity and its ability to retain organic material, therefore, means that although the dominant lateral movements of organic material will still occur during large overbank flows, smaller ‘pulse’ inputs will occur with each in-channel rise and fall in water level. In dryland rivers, where large overbank flows may only occur every seven or more years, these small ‘pulse’ inputs of organic material may well be vital for the integrity of the system. This paper describes the contemporary complexity of a channel in a regulated and an unregulated reach of the Barwon–Darling and compares this with cross-sections surveyed in 1886. We show that flow regulation has greatly reduced channel complexity. We estimate the potential organic matter input to each bench level within the channel (using data collected under near natural riparian conditions) and measure the contemporary organic loads within the channel of the regulated and unregulated reach. This modelling suggests that the development of water resources has reduced the complexity of the channel in the regulated reach, resulting in a potential decrease in the retention of organic matter in this region of the river. The importance of this organic matter to the aquatic food web of the Barwon–Darling River is also demonstrated.

We analyzed the value of digital epiluminescence microscopy (DELM) for the long-term follow-up of atypical nevi. Patients (n=530) were prospectively categorized into defined melanoma risk groups and followed by clinical and epiluminescence microscopy (ELM) examinations. Atypical nevi (n=7001) were additionally followed by DELM. During follow-up (median 32.2 months), we detected 53 melanomas among 637 excised lesions (8.3% overall chance of success). The chance of success for melanoma detection among lesions suspicious by ELM criteria was increased to 17% when additional DELM-documented changes were present. Moreover, 18 of the 53 melanomas were exclusively identified by DELM-documented changes, indicating that DELM increased the sensitivity of the ELM analysis by identifying additional melanomas. However, for lesions exclusively excised due to DELM changes, the chance of success was lower than for ELM (5.2 vs 11.8%). Excisions due to mere DELM changes detected 66.7% of melanomas in familial atypical mole and multiple melanoma (FAMMM) and 32.5% of melanomas in atypical mole syndrome (AMS) patients. We conclude that DELM is a valuable tool for the long-term follow-up of atypical nevi, especially in the high-risk groups of FAMMM and AMS patients. Randomized controlled trials are needed to validate the data from this clinical trial.

Floodplain–river ecosystems are natural fragmented systems because of periodic hydrological connections. The integrity of these ecosystems is thought to be dependent, in part, upon exchanges of energy and matter between patches, such as the main river channel, adjacent floodplain surface and other morphological features, during periods of connection. Flow regulation and its associated infrastructure change the natural character of fragmentation in floodplain–river ecosystems, and have important consequences for their overall productivity. This paper considers the influence of water resources development on the character of fragmentation in a large lowland river in SE Australia. Large-scale water resources development in the Macintyre River, Australia, has significantly altered the spatial and temporal patterns of hydrological connections. The construction of weirs and other embankments on the lower Macintyre River floodplain prevents water movement through a series of anabranch channels thereby reducing the availability of these floodplain patches by 55%. In addition, because of flow regulation, hydrological connections to these channels occur up to 22% less often. Data are presented showing the impacts of these changes on the potential supply of dissolved organic carbon from the anabranch channels during periods of inundation over a 98-year period. Reductions of up to 98% of potential dissolved organic carbon supply from some anabranch channels were noted.

Floodplains are ecotones that form a transition between aquatic and terrestrial environments. These important ecosystems can be described as dynamic spatial mosaics in which water plays an important role in connecting various patches on the floodplain surface. Hydrological connections facilitate the exchange of carbon and nutrients between the river channel and the floodplain and therefore influence the productivity of the entire river system. This paper examines the influence of hydrological connections on the potential exchange of dissolved organic carbon between a large Australian floodplain to a river channel, and the effects of land and water developments on these exchanges. The paper proposes that an understanding of floodplain ecosystems requires an interdisciplinary approach—a recognition of the importance of the three disciplines hydrology, geomorphology and ecology. Large-scale water-resources and floodplain development has significantly altered the spatial and temporal patterns of hydrological characteristics in the Lower Balonne floodplain, Australia. The magnitude, frequency and duration of flooding events have all been reduced. The construction of levees and water storages has also reduced the reactive floodplain surface area. The presented data show the impacts of these changes on the potential supply of dissolved organic carbon from the floodplain surface during periods of inundation. Annual reductions of up to 1293 tonnes of dissolved organic carbon supply were noted and reductions were especially significant for floods with an average recurrence interval of 2 years or less. Some small flood events no longer facilitate the potential supply of dissolved organic carbon from the floodplain to the river channel because of water-resources and floodplain developments.

The allocation of water for environmental purposes is a key management issue in many dryland regions. Many different methods have been developed for determining environmental water requirements but these are not directly applicable to dryland rivers because of inherent flow and habitat variability. An ecosystem approach for determining environmental water allocations in dryland regions is presented in this paper. This four-step process involves (1) a hierarchical characterisation of the river system, to assess what mesohabitats are present and where they are located; (2) the determination of flows that would inundate these habitats and perform other key ecological processes; (3) hydrological analyses in which the key hydrological signatures of the river are identified and the impact of water resource development on these is determined; and (4) the derivation of a water management decision tree that enables managers to allocate water to consumptive users during individual flood pulses (events). It is recommended that the flood pulse should be the focus for environmental flow management in dryland regions. If rivers are indeed nested hierarchies, then a change in hydrological behaviour at the scale of a flood pulse will, with time, extend throughout the hydrological hierarchy. Current environmental flow management strategies in dryland river systems are essentially focused at the flow regime and history scale; this is inappropriate given the inherent flow variability of these systems. The ecosystem approach is outlined for the Condamine-Balonne River, a large dryland system in Australia.

Water resource development has had a major impact on the hydrology of the Barwon–Darling River, a large dryland river in southeast Australia. Flows are highly modified through the presence of nine headwater dams, 15 main channel weirs and 267 licensed water extractors. Median annual runoff has been reduced by 42% over a 60-year period. Small flood events (e.g. Average Recurrence Interval of

Variations of channel substrate composition are described for a regulated river which has experienced channel change since dam completion. Sediment samples were obtained using bulk (grab) sampling and freeze-coring. Data derived from the two methods are shown to differ. Bulk-sample data describe the bed surface layer; its grain-size variations are related to bedform. Freeze-core data describe the sub-surface structure and the fine size-grades. The gravel framework-supported substrate of the control reaches constrasts with the sand-dominated substrate of the aggraded reach, although in both cases the substrate coarsens upwards. In the former this relates to the development of a sand matrix within the gravel-framework substrate, and in the latter, sand-bed channel, to the progressive addition of a gravel component towards the surface which is related to the process of channel change. At the local-scale, bedform is shown to exert an important control on the character of substrate change induced by flow regulation.