CERES :: Browsing by Author "Grabowski, Robert C."

Browsing by Author "Grabowski, Robert C."

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Open Access
Analysis of scaling relationships for flood parameters and peak discharge estimation in a tropical region
(IWA Publishing, 2024-01-23) Mazivanhanga, Charles; Grabowski, Robert C.; Perez Sanchez, Eunice; Carballo Cruz, Victor R.
Relationships between peak discharges and catchment size (e.g., flood scaling) in a catchment have the potential to support new river flood forecasting approaches but have not been tested in tropical regions. This study determined flood scaling relationships between peak discharge and nested drainage areas in the La Sierra catchment (Mexico). A statistical power law equation was applied to selected rainfall– runoff events that occurred between 2012 and 2015. Variations in flood scaling parameters were determined in relation to catchment descriptors and processes for peak downstream discharge estimation. Similar to studies in humid temperate regions, the results reveal the existence of log-linear relationships between the intercept (α) and exponent (θ) parameter values and the log–log power–law relationships between α and the peak discharge observed from the smallest headwater catchments. The flood parameter values obtained were then factored into the scaling equation (QP = αAθ) and successfully predicted downstream flood peaks, especially highly recurrent flood events. The findings contribute to a better understanding of the nature of flood wave generation and support the development of new flood forecasting approaches in unregulated catchments suitable for non-stationarity in hydrological processes with climate change.
Open Access
Assessing n-alkane and neutral lipid biomarkers as tracers for land-use specific sediment sources
(Elsevier, 2023-03-28) Wiltshire, C.; Waine, Toby; Grabowski, Robert C.; Meersmans, Jeroen; Thornton, B.; Addy, S.; Glendell, M.
Sediment fingerprinting (SF) methods using taxonomic-specific biomarkers such as n-alkanes have been successfully used to distinguish sediment sources originating from different land uses at a catchment scale. In this study, we hypothesise that using a combination of soil biomarkers of plant, fungal and bacterial origin may allow greater discrimination between land uses in SF studies. Furthermore, we assess if the inclusion of short chain (shorter than C22) neutral lipid fatty acids (SC-NLFA) improves land use discrimination, considering the Loch Davan catchment (34 km2) in Scotland as a case study. Fatty acids are commonly used to measure abundance and diversity of soil microbial and fungal communities. The spatial distribution of these soil communities has been shown to depend mainly on soil properties and, therefore, soil types and land management practices. The n-alkane and SC-NLFA concentrations and their compound specific stable isotope signatures (CSSI) in four land cover classes (crop land, pasture, forest, and moorland) were determined and their contribution to six virtual sediment mixture samples was modelled. Using a Bayesian un-mixing model, the performance of the combined n-alkane and SC-NLFA biomarkers in distinguishing sediment sources was assessed. The collection of new empirical data and novel combinations of biomarkers in this study found that land use can be distinguished more accurately in organic sediment fingerprinting when combining n-alkanes and SC-NLFA or using SC-NLFA and their CSSI alone. These results suggest that fingerprinting methods using the output of unmixing models could be improved by the use of multiple tracer sets if there is a commensurate way to determine which tracer set provides the “best” capacity for land use source discrimination. This new contribution to the organic sediment fingerprinting field highlights that different combinations of biomarkers may be required to optimise discrimination between soils from certain land use sources (e.g., arable-pasture). The use of virtual mixtures, as presented in this study, provides a method to determine if addition or removal of tracers can improve relative error in source discrimination. Combining biomarkers from different soil communities could have a significant impact on the identification of recent sources of sediment within catchments and therefore on the development of effective management strategies.
Open Access
Assessing the efficacy and mechanisms of glycol-contaminated water treatment through floating treatment wetlands
(IWA Publishing, 2023-12-01) Lyu, Tao; Williams, Randy; Exton, Benjamin; Grabowski, Robert C.
The growing concerns surrounding water pollution and the degradation of ecosystems worldwide have led to an increased use of nature-based solutions (NbSs). This study assessed the feasibility of using floating treatment wetlands (FTWs) as an NbS to treat propylene glycol-contaminated water and quantitatively investigated different removal pathways. With an environmentally relevant concentration of propylene glycol (1,250 mg/L), FTWs containing Acorus calamus and mixed species demonstrated the highest average glycol mass removal efficacy (99%), followed by Carex acutiformis (98%), Juncus effusus (93%), and the control group without plants (10%) after 1 week. Additional mesocosm-scale experiments with varying FTW configurations, including surface coverage to reduce evaporation and photodegradation processes, and the addition of antibiotics to inhibit microbial activity, were conducted to quantify glycol removal pathways. Mass balance analysis results revealed that microbial biodegradation (33.3–39.7%) and plant uptake (37.9–45.2%) were the primary pathways for glycol removal. Only 15.5–19.5% of the glycol removal via evaporation and photodegradation was accounted in this study, which may be attributed to the mesocosm experimental setup (static water and no wind). Aligned with the broader discussion regarding biodiversity improvements and carbon storage capacity, this study demonstrated that FTWs are an environmentally friendly and effective NbS for addressing glycol-contaminated water.
Open Access
Assessing the source and delivery of organic carbon at a catchment scale using a combined sediment fingerprinting and carbon loss modelling approach
(EGU: European Geophysical Union, 2022-05-27) Wiltshire, Catherine; Waine, Toby; Grabowski, Robert C.; Glendell, Miriam; Thornton, Barry; Addy, Steve; Meersmans, Jeroen
Quantifying land use sources and understanding the dynamics of organic carbon (OC) in river catchments is essential to reduce both on-site and off-site impacts of soil OC erosion. The lake area of Loch Davan, located in Aberdeenshire, Scotland, has been significantly reduced over the last century due to sediment inputs and, in this study, we aimed to identify the primary source(s) and delivery of OC to the loch’s main feeder stream, Logie Burn and its major tributaries.
Open Access
Assessing the source and delivery processes of organic carbon within a mixed land use catchment using a combined n-alkane and carbon loss modelling approach
(Springer, 2022-04-08) Wiltshire, Katy; Glendell, M.; Waine, Toby; Grabowski, Robert C.; Meersmans, Jeroen
Purpose: Understanding fluxes of soil organic carbon (OC) from the terrestrial to aquatic environments is crucial to evaluate their importance within the global carbon cycle. Sediment fingerprinting (SF) is increasingly used to identify land use-specific sources of OC, and, while this approach estimates the relative contribution of different sources to OC load in waterways, the high degree of spatial heterogeneity in many river catchments makes it challenging to precisely align the source apportionment results to the landscape. In this study, we integrate OC SF source apportionment with a carbon loss model (CLM) with the aim of: (i) reducing ambiguity in apportioning OC fluxes when the same land use exists in multiple locations within a catchment; and (ii) identifying factors affecting OC delivery to streams, e.g., buffer zones. Methods: Two main approaches were used in this study: (i) identification of the sources of freshwater bed sediment OC using n-alkane biomarkers and a Bayesian-based unmixing model; and (ii) modelling and analysis of spatial data to construct a CLM using a combination of soil OC content modelling, RUSLE soil erosion modelling and a connectivity index. The study was carried out using existing OC and n-alkane biomarker data from a mixed land use UK catchment. Results: Sediment fingerprinting revealed that woodland was the dominant source of the OC found in the streambed fine sediment, contributing between 81 and 85% at each streambed site. In contrast, CLM predicted that arable land was likely the dominant source of OC, with negligible inputs from woodland. The areas of the greatest OC loss in the CLM were predicted to be from arable land on steeper slopes surrounding the stream channels. Results suggest extensive riparian woodland disconnected upslope eroded soil OC and, concomitantly, provided an input of woodland-derived OC to the streams. It is likely the woodland contribution to streambed OC is derived from litter and leaves rather than soil erosion. Conclusion: This study demonstrates how location-specific OC sources and delivery processes can be better determined using sediment fingerprinting in combination with CLM, rather than using sediment fingerprinting alone. It highlights that, although wooded riparian buffer strips may reduce the impact of upslope, eroded soil OC on waterways, they could themselves be a source of OC to stream sediments through more direct input (e.g., organic litter or leaf debris). Characterising this direct woodland OC as a separate source within future fingerprinting studies would allow the contributions from any eroded woodland soil OC to be better estimated.
Open Access
Catchment and climatic influences on spatio-temporal variations in suspended sediment transport dynamics in rivers
(IWA Publishing, 2023-08-04) Shin, Jae hun; Grabowski, Robert C.; Holman, Ian P.
Suspended sediment concentration (SSC) is an important attribute for water resources management. However, the interactions between climate and catchment characteristics that control the temporal variability of SSC in rivers are not fully resolved. The study aim is to evaluate how these variables influence spatial and seasonal variations in SSC dynamics at a continental scale. Daily SSC (mg/l) and site attribute data from 120 sites (USA) with minimum 10 years of record (1971–2000) were analysed. New indicators of SSC dynamics (magnitude and frequency) were developed and applied annually and seasonally. Geographically weighted regression (GWR) models were created for each ordinary least squares (OLS) regression model, and GWR coefficients were analysed by ecoregion. Land cover, rainfall and erosivity, baseflow index and soil texture were the most common variables in the OLS models. GWR coefficients displayed significant variation across the continent. Agricultural cover was positively associated with low frequency SSC events, while urban and forest cover predicted higher frequency events, except in the desert areas. PPT30 was generally a negative predictor for SSC magnitude, except the marine west coasts forests. These findings on catchment and climate controls on SSC will support future predictive models of SS transport dynamics.
Open Access
Clay swelling: role of cations in stabilizing/destabilizing mechanisms
(American Chemical Society , 2022-01-17) Chen, Wen L.; Grabowski, Robert C.; Goel, Saurav
The stepwise hydration of clay minerals has been observed repeatedly in studies, but the underlying mechanism remains unclear. Previous numerical studies confirmed the presence of one-water layer (1W) and two-water layer (2W) hydration states. However, the undisturbed transition between these hydration states has never been captured. Using molecular dynamics simulation, this study (i) simulated for the first time the free 1W–2W transition during clay hydration and (ii) identified the underlying mechanism to be the detachment of cations from the clay surface and the formation of a shell of water molecules around the cation. The swelling dynamics of clay was found to be affected by the clay charge, clay mineralogy, and counterions through complex cation–clay interactions, cation hydration capacity, and cation migration rate.
Open Access
Climate impacts on soil susceptibility to erosion.
(Cranfield University, 2020-09) Dowdeswell-Downey, Emily; Grabowski, Robert C.; Rickson, Jane R.
Soil erosion threatens soil sustainability and the provision of ecosystem services and is predicted to increase in the future with climate change. Soil erodibility, the susceptibility of soil to erosion, is often estimated as a constant variable but the best indicator of erodibility is aggregate stability, which is a dynamic soil property and has been observed to vary with changes in local climatic conditions. Aggregate stability is influenced by biological stabilisation and the soil microbial community are known to respond to changes in climatic conditions, yet whether aggregate dynamics can be explained by shifts in the soil microbial community has not been fully investigated. This thesis aims to investigate the influence of climatic conditions, in terms of soil temperature and moisture content, on aggregate stability, and thus soil erodibility, and whether these dynamics are explained by climate-induced changes in the soil microbial community. Environmental chambers and a rainfall simulator were used to examine the effects of climatic conditions and rainfall on aggregate stability and soil microbial properties as indicators of biological stabilisation in single-layer and multi-layered aggregate microcosms. The key findings show that temperature and moisture content significantly affected aggregate stability and the influence of soil temperature and moisture on soil microbial properties is soil texture dependent. Soil microbial properties were significant predictors of aggregate stability. Aggregate stability did not differ between climate scenarios in seasonal treatments but was significantly lower in seasonal treatments compared to constant seasons. Soil temperature and moisture significantly affected soil erodibility related to changes in aggregate stability and the soil microbial community. Rainfall significantly affected microbial properties in eroded soil and selectively mobilised a fungal-dominated component of the microbial community, influenced by preceding climatic treatments. The research highlights the further need to (i) recognise the role of climate-driven microbial shifts mediating aggregate stability mechanistically; and (ii) integrate knowledge on aggregate- scale mechanisms across larger spatial scales.
Open Access
Controls on anastomosis in lowland river systems: Towards process-based solutions to habitat conservation
(Elsevier, 2017-09-12) Marcinkowski, Paweł; Grabowski, Robert C.; Okruszko, Tomasz
Anastomosing rivers were historically common around the world before extensive agricultural and industrial development in river valleys. Few lowland anastomosing rivers remain in temperate zones, and the protection of these river-floodplain systems is an international conservation priority. However, the mechanisms that drive the creation and maintenance of multiple channels, i.e. anabranches, are not well understood, particularly for lowland rivers, making it challenging to identify effective management strategies. This study uses a novel multi-scale, process-based hydro-geomorphological approach to investigate the natural and anthropogenic controls on anastomosis in lowland river reaches. Using a wide range of data (hydrologic, cartographic, remote-sensing, historical), the study (i) quantifies changes in the planform of the River Narew, Poland over the last 100 years, (ii) documents changes in the natural and anthropogenic factors that could be driving the geomorphic change, and (iii) develops a conceptual model of the controls of anastomosis. The results show that 110 km of anabranches have been lost from the Narew National Park (6810 ha), a 42% reduction in total anabranch length since 1900. The rates of anabranch loss have increased as the number of pressures inhibiting anabranch creation and maintenance has multiplied. The cessation of localized water level and channel management (fishing dams, water mills and timber rafting), the loss of traditional floodplain activities (seasonal mowing) and infrastructure construction (embanked roads and an upstream dam) are contributing to low water levels and flows, the deposition of sediment at anabranch inlets, the encroachment of common reed (Phragmites australis), and the eventual loss of anabranches. By identifying the processes driving the loss of anabranches, this study provides transferable insights into the controls of anastomosis in lowland rivers and the management solutions needed to preserve the unique anastomosing river pattern and diverse wet grasslands that are central to the conservation value of lowland floodplains.
Open Access
The current state of the use of large wood in river restoration and management
(Wiley, 2019-03-25) Grabowski, Robert C.; Gurnell, Angela M.; Burgess‐Gamble, Lydia; England, Judy; Holland, David; Klaar, Megan J.; Morrissey, Ian; Uttley, Chris; Wharton, Geraldene
Trees fall naturally into rivers generating flow heterogeneity, inducing geomorphological features, and creating habitats for biota. Wood is increasingly used in restoration projects and the potential of wood acting as leaky barriers to deliver natural flood management by ‘slowing the flow’ is recognised. However, wood in rivers can pose a risk to infrastructure and locally increase flood hazards. The aim of this paper is to provide an up‐to‐date summary of the benefits and risks associated with using wood to promote geomorphological processes to restore and manage rivers. This summary was developed through a workshop that brought together academics, river managers, restoration practitioners and consultants in the UK to share science and best practice on wood in rivers. A consensus was developed on four key issues: (i) hydrogeomorphological effects, (ii) current use in restoration and management, (iii) uncertainties and risks and (iv) tools and guidance required to inform process‐based restoration and management.
Open Access
Do temperature and moisture conditions impact soil microbiology and aggregate stability?
(Springer, 2023-08-29) Dowdeswell-Downey, Emily; Grabowski, Robert C.; Rickson, R. Jane
Purpose: Studies predicting the impacts of climate change on erosion have considered numerous variables, such as rainfall erosivity and vegetation cover, but have not considered potential changes in soil erodibility. Erodibility is an intrinsic property of the soil, strongly correlated with the stability of soil aggregates. It is influenced by soil physico-chemical attributes, including the microbiological community. The study aim was to determine how shifts in temperature and moisture conditions, which other studies have shown affect microbiological communities, might affect aggregate stability. Methods: Using an experimental approach with laboratory microcosms, aggregates from a sandy loam soil and a clay soil were incubated at three temperatures and three moisture conditions in a factorial experimental design. Aggregate stability was quantified using rainfall simulation. Microbiological indicator metrics were measured to evaluate treatment microbiological impacts, including community composition (PLFA), biomass carbon, and respiration. Results: Temperature and moisture content affected aggregate stability significantly, but differently for the two soil types tested. For the sandy loam soil, aggregate stability decreased significantly with increasing moisture content. For the clay soil, aggregate stability increased significantly with increasing temperature. For both soil textures, temperature and moisture content affected microbiological community composition and respiration. Regression analysis indicated that microbiological properties were significant predictors of aggregate stability. Conclusion: Our results emphasise the dynamic nature of soil aggregate stability. Changes in microbiological metrics suggest possible biological mechanisms for aggregate stability changes, which should be investigated further to better understand the potential impacts of climate change on soil erodibility and erosion.
Open Access
Effects of parental exposure to amitriptyline on the survival, development, behavior, and gene expression in zebrafish offspring
(Elsevier, 2023-12-06) Liu, Anqi; Chen, Chen; Chen, Kun; Shi, Yanhong; Grabowski, Robert C.; Qiu, Xuchun
In mammals, parental exposure to amitriptyline (AMI) has been proven to contribute to congenital disabilities in their offspring. However, no studies have paid attention to the adverse effects of parental exposure to amitriptyline on fish offspring. In this study, we exposed adult zebrafish (F0) to AMI (0.8 μg/L) for 21 days. Subsequently, these zebrafish (F0) were allowed to mate, and their offspring (F1) were collected to culture in clean water for 5 days. The mortality rate, average hatching time, and heart rate at 48 h post-fertilization (hpf) of F1 were investigated. Our results showed that parental exposure to AMI induced tachycardia and increased mortality in F1 zebrafish. Under a light/dark transition test, F1 larvae born from AMI-exposed parents exhibited lower locomotor activity in the dark period and decreased thigmotaxis in the light period. The transcriptome analysis showed that parental AMI exposure dysregulated some key pathways in their offspring. Through the prediction of key driver analysis, six differentially expressed genes (DEGs) were revealed as key driver genes involved in protein processing in endoplasmic reticulum (hspa5, hsp70.1, hsp90a), ribosome (rps27a) and PPAR signaling pathway (pparab and fabp2). Considering that the concentration of AMI residual components in natural water bodies may be over our test concentration (0.8 μg/L), our findings suggested that toxicity of parental exposure to the offspring of fish should receive greater attention.
Open Access
An example application of the CEN Water quality — Guidance standard for assessing the hydromorphological features of rivers to the River Frome, Dorset, Southern England
(UK Centre for Ecology and Hydrology, 2020-10-01) Gurnell, Angela M.; Grabowski, Robert C.
This report documents a comprehensive application of the framework proposed in CEN Standard CEN/ TC 230/ WG 25/ EN14614 to the River Frome, Dorset, Southern England. Therefore, this report needs to be read with reference to that Standard. The framework was first developed in REFORM, a European Union Framework 7 project (Grant Agreement 282656), established to improve the success of hydromorphological restoration. The Standard determines the natural hydromorphological condition of rivers for many applications. It is appropriate for long-term, catchment-scale management, e.g. river basin planning and implementation. It is also able to support assessments for site-scale, project delivery, e.g. flood management schemes, channel maintenance and channel restoration. The hierarchical and multiscale nature of the analysis illustrated in this report provides causative links between catchment processes and local scale hydromorphological conditions; for example, how catchment scale issues influence fine sediment erosion, transfer and deposition. In this way it can facilitate the application of a DPSIR (Drivers, Pressures, State, Impact, Response) model of management intervention, illustrate causes and consequences, and help target sustainable management solutions.
Open Access
Exploring social-ecological impacts on trade-offs and synergies among ecosystem services
(Elsevier, 2022-04-12) Wang, Xiaoyu; Peng, Jian; Luo, Yuhang; Qiu, Sijing; Dong, Jianquan; Zhang, Zimo; Vercruysse, Kim; Grabowski, Robert C.; Meersmans, Jeroen
An in-depth understanding of the complex patterns of ecosystem services (ESs) interactions (i.e., synergies or trade-offs) based on social-ecological conditions is an important prerequisite for achieving sustainable and multifunctional landscapes. This study aimed to explore how ESs interactions are influenced by social-ecological factors. Taking the Sutlej-Beas River Basin as a case study area, where the linkages between ESs interactions and social-ecological processes are poorly understood, ESs interactions were identified through principal component analysis and correlated with a range of social-ecological factors, which were explored spatially based on ES bundles. The results revealed two dominant types of ESs interactions, namely multifunctionality-related synergies and grain production-related trade-offs. Population, nighttime light, precipitation, temperature, and soil clay content were all positively correlated with the two ESs interactions. Contrarily, elevation and soil sand content were negatively correlated with the two ESs interactions. Four main ES bundles were identified, which spatially describe the presence of ESs synergies and/or trade-offs in relation to social-ecological factors. This study provides a feasible way to explore the spatial differentiation and influencing factors impacting the interactions between ESs, which can provide a basis for an integrated watershed-based management of ESs.
Open Access
From field to stream: Tracing streambed organic carbon origins at a catchment scale
(EGU: European Geophysical Union, 2021-04-30) Wiltshire, Katy; Glendell, Miriam; Waine, Toby; Grabowski, Robert C.; Thornton, Barry; Meersmans, Jeroen
Open Access
Functional traits of hyporheic and benthic invertebrates reveal importance of wood-driven geomorphological processes to rivers
(Wiley, 2019-06-04) Magliozzi, Chiara; Usseglio-Polatera, Philippe; Meyer, Albin; Grabowski, Robert C.
1.Large wood (LW) is a natural element of river environments and an integral component of many river restoration schemes to promote biodiversity. It is an important habitat in itself, but it also induces a wide range of hydraulic, hydrological, geomorphological, and chemical conditions that influence the ecological community. However, the effects of hydro‐geomorphological processes induced by LW on local benthic and hyporheic invertebrates have not been well characterized. 2.A functional approach was applied to invertebrate data collected in a field survey at sites with LW and without LW (control), to investigate the response of hyporheic and benthic invertebrates’ trait profiles in response to local LW‐induced processes. 3.We hypothesized LW sites to be associated with different trait modalities than control sites in relation to wood‐induced processes and conditions (i.e. hyporheic exchange flow, oxygen availability, temporal stability, organic matter, denitrification, hydraulic conductivity). Multivariate analyses and Partial Least Squares (PLS) Path Modelling were used to detect the differences in trait profiles between LW and control sites and to study the variation of traits as a function of hydrological, sedimentological, physical and chemical variables. 4.Biological (i.e. aquatic stages, reproduction), physiological (i.e. dispersal, feeding habits) and behavioural (i.e. substrate preferences) trait utilization by the hyporheic meiofauna differed between LW and control sites. At LW sites, the hyporheic meiofaunal assemblage was significantly associated with aquatic active dispersal, aquatic eggs and hard substrate preferences. This trait category selection was linked to changes in physical‐sedimentological processes at LW sites when compared to control sites. Macrofaunal benthic and hyporheic functional traits did not differ significasignificantly between wood and control sites, suggesting similar functioning of these assemblages at the surface‐subsurface interface. 5.This study found that LW affects invertebrate traits by altering fluvial processes to produce, locally, a mosaic of habitats. Hyporheic meiofauna trait responses to LW‐processes have suggested (i) the crucial role of LW in supporting river benthic zone functioning, and thus (ii) a possible benefit to river restoration by enhancing functional interactions among different ecological niches.
Open Access
Green nourishment: an innovative nature-based solution for coastal erosion
(Frontiers, 2022-02-09) Chen, Wen L.; Muller, Peter; Grabowski, Robert C.; Dodd, Nicholas
Coastal erosion poses an urgent threat to life and property in low-lying regions. Sand nourishment is increasingly used as a nature-based solution but requires significant natural resources and replenishment over time. In this study, a novel form of nourishment is explored that combines shoreface nourishment and seagrass restoration to mitigate coastal erosion (i.e., green nourishment). Using the coastal morphodynamic model Xbeach, the impact of seagrass planting on wave energy dissipation, sediment erosion and transport, and morphological evolution of a cross-shore profile was studied for mild wave conditions and an intense storm. Model results indicate that a seagrass meadow enhances the wave energy dissipation provided by a shoreface nourishment, and suggests that it may be particularly effective in sediment transport mitigation when implemented in a sheltered nearshore area. The shoreface nourishment reduced the wave height on the seagrass meadow, and reduced the rate of seagrass destruction by deposition or erosion above the grass height after the storm event. Green nourishment also reduced beach foreshore erosion caused by a simulated storm event. An alternative, more cost-effective planting technique using seagrass seeds was explored, which showed similar coastal erosion protection benefits for seagrass transplants. This modeling study found that green nourishment is potentially an effective nature-based solution for coastal erosion and flooding on sandy coasts, and future studies are recommended to evaluate its morphological, ecological and flood risk reduction benefits in the field.
Open Access
A hierarchical multi-scale framework and indicators of hydromorphological processes and forms
(European Commission within the 7th Framework Programme, 2014-10-30) Gurnell, Angela M.; Bussettini, M.; Camenen, B.; González Del Tánago, M.; Grabowski, Robert C.; Hendriks, D.; Henshaw, A.; Latapie, A.; Rinaldi, M.; Surian, N.
Background and Introduction to Deliverable 2.1. Work Package 2 of REFORM focuses on hydromorphological and ecological processes and interactions within river systems with a particular emphasis on naturally functioning systems. It provides a context for research on the impacts of hydromorphological changes in Work Package 3 and for assessments of the effects of river restoration in Work Package 4. Deliverable 2.1 of Work Package 2 proposes a hierarchical framework to support river managers in exploring the causes of hydromorphological management problems and devising sustainable solutions. The deliverable has four parts. Part 1 (this volume) provides a full description of the hierarchical framework and describes ways in which each element of it can be applied to European rivers and their catchments. Part 2 includes thematic annexes which provide more detailed information on some specific aspects of the framework described in Part 1. Part 3 includes catchment case studies which present the application of the entire framework described in Part 1 to a set of European catchments located in different biogeographical zones. Part 4 includes catchment case studies which present a partial application of the framework described in Part 1 to a further set of European catchments.
Open Access
Human impact on river planform within the context of multi-timescale river channel dynamics in a Himalayan river system
(Elsevier, 2021-02-24) Vercruysse, Kim; Grabowski, Robert C.
Rivers are dynamic landscape features which are often altered by human activity, making it difficult to disentangle human impact on geomorphic change from natural river dynamics. This study evaluated the human impact on river planform change within the context of short- and long-term river channel dynamics in the Himalayan Sutlej and Beas Rivers, by (i) systematically assessing river planform change over centennial, annual, seasonal and episodic timescales; (ii) connecting observed changes to human-environment drivers; and (iii) conceptualising these geomorphic changes in terms of timescale-dependent evolutionary trajectories (press, ramp, pulse). Landsat imagery was used to extract components of the post-monsoon active river channel (1989-2018), using the modified Normalized Differences Water Index to identify the wet river area, and visible red to determine active gravel bars. Findings were compared with a historical map to represent the pre-dam period (1847-1850) and with data on potential driving factors of change (discharge, climate and land cover). River planform characteristics changed significantly over all timescales, exhibiting strong spatiotemporal variation between and within both rivers. Dam construction likely caused channel narrowing and straightening at the centennial scale (press trajectory). In the Sutlej, this process has continued over the last 30 years, likely enforced by the cumulative effect of water abstraction and climatic changes (ramp trajectory). In the Beas, the pattern of change in river planform metrics was less pronounced over the same period and more variable along the length of the river, possibly linked to different dam operations that maintain a higher degree of flow variability and peak flows (press trajectory). High local erosion rates caused by aggregate mining (episodic) in the Sutlej were also observed (pulse trajectory). Expressed as evolutionary trajectories, the observed responses to human activity confirm the importance of legacy effects of human impact on river systems, and stress the dependency on spatial and temporal scales to determine trajectories of change. The multi-timescale assessment and conceptualisation provide insights into different dimensions of human impact on river planform change, which is pivotal to developing holistic management strategies
Open Access
Hydroecological investigations on the hyporheic zone to support river management from reaches to catchments
(2018-06) Magliozzi, Chiara; Grabowski, Robert C.; Janes, Martin
The hyporheic zone (HZ) is an area of interaction between surface and ground waters in riverbeds. It is characterized by a diverse fauna and by a bidirectional flow (hyporheic exchange flow - HEF). HZ plays a signifi cant role in river ecosystems as location of major physical, biogeochemical and ecological processes. Yet, predicting HEF in rivers and assessing its ecological effects is challenging due to physical and biological process- interactions in time and space. This thesis investigates HEF from a hierarchical scaling perspective and it has two components: (i) physical, and (ii) biological. The fi rst component includes discriminating and integrating the drivers of HEF across spatial scales and developing a multiscale statistical method for river restoration planning. The second component consists of testing the interaction between physical and biological processes on in-channel large wood (LW), by quantifying, in the field, the effects on hyporheic and benthic invertebrates assemblages taxonomic structure and functional traits. The multiscale approach shows that suitable areas for HEF-focused restoration embed a summary of environmental information across the domains of hydrology, geomorphology, and ecology. Field results about invertebrates' taxonomic and functional metrics, demonstrate that the increased spatial and temporal variability of abiotic conditions at LW sites drives changes in abundance, biomass, diversity and functional traits of hyporheic meiofaunal assemblages. In contrast, benthic macrofaunal assemblages were less wood-impacted. To support restoration targeting the HZ, this research emphasizes the need to (i) recognize different spatial scales of HEF to identify the underlying processes; (ii) coordinate approaches to pool hyporheic data and create long-term datasets to quantitatively assess model predictions; and (iii) establish further knowledge on how LW effects HZ in different valleys and river types.