smartresearchtopicsdescription-3rdcohort

SMART EMJD – DESCRIPTION OF PROPOSED RESEARCH TOPICS

Call 2013

SMART’s overall objective is to train scientists to develop and adopt integrated

multidisciplinary approaches to the sustainable rehabilitation and maintenance of

river corridor ecosystems.

In particular SMART emphasises three multidisciplinary research areas that support

specific objectives and offer each doctoral candidate a challenging context for their

research project:

Research Area A: To advance relevant scientific knowledge of the resilience of river-

floodplain ecosystems to both natural and human induced changes in hydrological

connectivity and other stressors.

Research Area B: To focus on the central linkage between physical processes and

biota within river corridor ecosystems that fundamentally influence the potential of

fluvial systems to self regulate and attain good ecological quality in both ‘reference’

and ‘impacted’ situations.

Research Area C: To evaluate the potential to support or rehabilitate desired river

system functions in impacted systems (e.g. land use, hydropower, urban

development, flow-tidal interactions).

This document presents a list of proposed research topics for the SMART Joint

Doctorate. They are listed in the following table and a short description for each topic

is reported in the following pages, together with the research supervisors, the primary

and secondary university and, in some cases, the involved associate partner. The

code given to each topic reflects the correspondent primary and secondary institution

(“U”: University of Trento; “Q”: Queen Mary, University of London; “F”: Freie

Universitat Berlin).

Res. area Research topic

Prim. Univ.

Second.Univ.

A UQ1 Interactions among vegetation, morphology and quality of

water UniTN QMUL

B UQ2 Establishing the spatial and temporal structure of hydraulic

conductivity in alluvial floodplains using physical-based

meander modelling and luminescence dating

UniTN QMUL

B UQ3 Morphotexture of gravel-bed river bars UniTN QMUL

A UQ4 Isotopic, chemical and physical characterization of the

Presena glacier and of the Noce River basin UniTN QMUL

A UQ5

Modelling the effects of aquatic vegetation and colmation on

suspended sediment transport and hyporheic exchange of

permeable gravel bed rivers

UniTN QMUL

A UQ6 Climate Sensitivity of the Presena glacier UniTN QMUL

B UQ7 Bio-morphodynamic evolution of tidal systems UniTN QMUL

C UQ8 Hydroecological processes and nutrients cycling in

agricultural ditches UniTN QMUL

C UQ9 The role of morphological diversity in improving the health of

hydropower-regulated river systems UniTN QMUL

B UF1 Thermal dynamics in braided river corridors. UniTN FUB

A UF2 Environmental impacts of small hydropower plants UniTN FUB

B UF3 The mechanics of bed-load and grain dispersion in rivers bed UniTN FUB

B QU1 Investigating and modelling vegetation – fluvial morphology

interactions: bank erosion and accretion QMUL/UniTN

QMUL/ UniTN

B QU2

Exploring interrelationships between floods and

morphodynamics in braided rivers using multispectral

satellite data

QMUL UniTN

A QU3 Environmental impacts of hydrodynamic dredging QMUL UniTN

B QU4 Modelling the response of braided rivers and deltas to

unsteady sediment supply QMUL UniTN

C QU5 Next generation models for urban flood management. QMUL UniTN

B QU6 Quantifying the methodological uncertainty in empirical

estimates of gravel sediment transport QMUL UniTN

B FU1 3D riverscapes: An airscape perspective of river landscapes FUB UniTN

C FU2 Critical landscape elements along river corridors FUB UniTN

B FU3 Food web modeling in aquatic systems FUB UniTN

C FU4 Domesticated freshwaters: structure, function, and

biodiversity FUB UniTN

B FU5

River-floodplain connectivity in a lowland clay river corridor

(Prut River, Romania/Moldova): Governing factors of

hydrodynamics and productivity

FUB UniTN

C FQ1 Remobilization of contaminants out of estuarine sediments FUB QMUL

B FQ2 Ecology of root-endophytic fungi in riparian plants FUB QMUL

B FQ3 Hyporheic reactors: coupling hydrodynamic and biogeo-

chemical processes in the bed of permeable lowland rivers FUB QMUL

A FQ4 Interactive response of macrophytes, invertebrates and fish

to changing hydromorphologic conditions in rivers FUB QMUL

A FQ5 Microplastics in the river system FUB QMUL

B FQ6 Airborne and ground-based upscaling of findings on

groundwater-surface water interactions FUB QMUL

Research topic (UQ1)

Interactions among vegetation, morphology and quality of water

Supervisors: Aronne Armanini, Maurizio Righetti, Giorgio Rosatti, James

Brasington, Alexander Sukhodolov

Primary University: University of Trento (Italy)

Secondary University: Queen Mary, University of London (UK)

Associate Partner: IGB Berlin

Research Area: B

Description

The presence of plants, bushes or grass in river beds modifies the characteristics of flow

field in water courses. Typically, the velocity field which crosses the vegetation is slower

and more turbulent than the velocity field in reaches without vegetation. These

differences in velocities change the transport of mass through the vegetation and,

consequently, the chemical and biological equilibria of water are strongly influenced.

In this research, the student will face the study of relationships among the presence of

stems in bed streams, morphological changes and transport of mass both with

experimental and numerical approach. Some experimental results have been already

obtained at the University of Trento, concerning the interaction among plants, sediment

transport and flow field. This investigation has been conducted with vegetation uniformly

distributed on the bed of the channel. A further step of the investigation concerns the

effect of islands of vegetation on river morphology.

This situation is also affecting the environmental diversity inside the stream and have

effects also on transport of different chemical and biological scalars.

In the channel it will be possible to measure the flow and the turbulence field with the

PIV Technique both in the vegetated islands and in not vegetated areas.

There is the possibility to modelling numerically these interactions by adapting the

existing 2D numerical code already existing at CUDAM.

This approach will permit to understand the role of vegetation in the movements and

dispersion of chemical and biological components of water, for relating the vegetation

directly with the ecological equilibrium of rivers, and for defining the capacity of

vegetation of restoring the quality of waters.

References

Armanini A., Cavedon V., Righetti M. 2010, Sediment transport processes in vegetated streams, proceedings of 1° European IAHR Congress. Edinburgh, Scotland.

Armanini A., Righetti M., Grisenti,P. (2005), Direct measurements of vegetation resistance in prototype scale, J. Hydr. Res. 43 (5)., 481-487. Elliot, A.H. (2000). Settling of fine sediment in a channel with emergent vegetation, J. Hydr. Engnr. 126 (8), 570-577 Nepf, H.M. (1999). Drag, turbulence and diffusion in flow through emergent vegetation. Water Resources Research. 35(2): 479-489. Nepf H., Ghisalberti M. (2008). Flow and transport in channels with submerged vegetation, Acta

Geophysica, Vol. 56 (3), 756-777 Nikora, V. (2010). Hydrodynamics of aquatic ecosystems: an interface between ecology, biomechanics and environmental fluid mechanics, River Res. and Appl, Vol. 26 (4), 367-384. Righetti, M. , 2008, Flow analysis in a channel with flexible vegetation using double-averaging method, Acta Geophys. 56, 801-823 Wu, W., F. D. Shields Jr., S. J. Bennett, and S. S. Y. Wang (2005). A depth-averaged two-

dimensional model for flow, sediment transport, and bed topography in curved channels with

riparian vegetation, Water Res. Res., 41 Rosatti G., Cesari D, Bonaventura L (2005). Semi-implicit, semi-Lagrangian modelling for environmental problems on staggered Cartesian grids with cut cells. Journal of Computational Physics, vol. 204; p. 353-377

Resarch topic (UQ2)

Establishing the spatial and temporal structure of hydraulic conductivity

in alluvial floodplains using physical-based meander modelling and

luminescence dating

Supervisors: Guido Zolezzi, Alberto Bellin, Sven Lukas


Secondary University: Queen Mary University of London (UK)

Associate Partner: to be defined

Research Area: B

Description

Estimating the spatial structure of hydraulic conductivity in alluvial floodplain aquifers has

great scientific and practical relevance. At present it is mainly achieved through a

combination of geophysical surveys and statistical techniques. The recent development of

physically-based simulation models of long term river dynamics hasn’t been exploited so

far for this purpose despite its strong potential in this direction. The proposed research

project aims to further develop a physically based mathematical model of river

meandering evolution (Seminara et al., 2001) to predict the spatial structure of the

hydraulic conductivity in alluvial meandering floodplains. The research will integrate

mathematical modelling with field observations. The modelling development shall account

for sediment heterogeneity in the description of the flow-bed topography in meandering

channels (Sun et al., 2001) and for the floodplain vertical accretion rate, so to produce

3D grain size maps over geological timescales.

The chronological component of the vertical accretion rate will be established by

employing optically-stimulated luminescence dating (OSL) of silt- and sand-sized grains

extracted from cores and sedimentary exposures at key locations along meander bends.

This approach offers temporal resolution at the order of centuries to millennia (e.g.

Rodnight et al., 2005) and will be carried out at the luminescence laboratory at QMUL.

Together, this dual approach of numerical modelling and geological fieldwork will

allow a deeper level of understanding than could be achieved by employing one of these

approaches on it’s a own.

References

Rodnight, H., Duller, G.A.T., Tooth, S., Wintle, A.G.. 2005. Optical dating of a scroll-bar sequence

on the Klip River, South Africa, to derive the lateral migration rate of a meander bend. The

Holocene, 15: 802-811.

Seminara G., Zolezzi G., Tubino M., Zardi D., 2001 Downstream and upstream influence in river

meandering. Part 2. Planimetric development. Journal of fluid mechanics, v. 438, p. 213-230.

Sun, T., P. Meakin, and T. Jøssang (2001), A Computer Model for Meandering Rivers with Multiple

Bed Load Sediment Sizes 2. Computer Simulations, Water Resour. Res., 37(8), 2243-2258.


Morphotexture of gravel-bed river bars

Supervisors: Guido Zolezzi, Walter Bertoldi, Marco Tubino, James Brasington,

Jonathan Laronne



Associate Partner: Ben Gurion University of the Negev (Israel)

Research Area: B

Description

Alternate bars can be viewed as benchmark large scale bedforms in alluvial rivers

because they represent fundamental morphodynamic units of a variety of channel

patterns, from single to multiple-thread. In gravel-bed rivers they often present

distinctive morphotextural properties, with bar tops often less armored compared with

the nearby channels. The reason for this difference may be attributed to the controlling

effect of bed topography on the duration of recession for any given hydrograph, any part

of the channel higher than the thalweg experiencing a much shorter duration of bedload

transporting flow (Laronne & Shlomi, 2007). A comprehensive insight on the process is

lacking at present and this is also one of the major limitations presently faced by

predictive mathematical models of gravel-bed rivers morphodynamics.

The proposed research aims to provide a quantitative explanation of the above process

through a combination of modelling and analysis of high spatial resolution field data on

the morpho-texture and dynamics of gravel bars taken from rivers within different

hydrological settings, from temperate to arid. The modelling component can either

include mathematical or physical modelling for alternate bars stability and growth under

unsteady flow conditions with multiple grain size, building on previous approaches

(Tubino, 1991, Lanzoni and Tubino, 1999). In addition, state-of-the-art field monitoring

using a combination of terrestrial photogrammetry, laser scanning and acoustic methods

will be used to provide detailed coupled measurements of sediment transport and the

evolution of bar surface facies as they evolve during and between floods (e.g., Hodge et

al., 2009a,b). Such data will be used to provide a high resolution empirical framework

essential for robust model parameterization and testing.

References

Hodge RA, Brasington J, Richards KS. 2009. Characterization of grain-scale fluvial morphology

using TLS. Earth. Surf. Proc. Landforms, 34, 954-968.

Hodge RA, Brasington J, Richards KS. 2009. Analysing laser-scanned digital terrain models of

gravel bed surfaces: linking morphology to sediment transport processes and hydraulics.

Sedimentology 56, 2024-2043.

Lanzoni S.; Tubino M. 1999. Grain sorting and bar instability J. Fluid Mech. 393, 149-174

Laronne, J.B. Shlomi, Y., 2007. Depositional character and preservation potential of coarse grained

sediments deposited by flood events in hyper-arid braided channels in the Rift Valley, Arava, Israel.

Sedimentary Geology, 195(1-2), 21-37

Tubino M. 1991 Growth of alternate bars in unsteady flow. Water Res. Res., 27(1), 37-52.


Isotopic, chemical and physical characterization of the Presena

glacier and of the Noce River basin

Supervisors: Alberto Bellin, Simon Carr



Associate Partner: Edmund Mach Foundation (Italy)

Research Area: A

Description

This research foresees two related components. First, an extensive and detailed

characterization of the structure and internal flow-dynamics for the Presena glacier will

be performed. Second, the spatial and temporal dynamics of the basin of river Noce will

be characterized using stable isotopes.

For the first component ice and snow samples will be collected with high spatial and

temporal resolution in order to characterize glacier flow behavior, using quantities such

as stable isotopes (2H and 18O) concentrations, snowpack level, electrical conductivity

and biological indicators, as well as physical survey of ice flow. The goal of this

component of the study will be to investigate mixing processes occurring in the glacier.

Furthermore, since this study will be conducted in collaboration with Meteotrentino

(meteorological office of the Province of Trento), it will be also estimated the efficiency of

the methods actually used to protect the glacier during summer.

The second component focuses on the basin of River Noce, where the Presena Glacier is

located. This basin is of particular interest since, depending on the period of the year, its

behavior can be dominated by snow melting, glacier ablation, rainfall precipitation or

groundwater discharge, each of which will have different isotopic ‘fingerprints’.

Furthermore different tributaries will display different seasonal behaviors depending on

their location and it will be also estimated the impact of artificial reservoir on the

discharge of the river.


Modelling the effects of aquatic vegetation and colmation on suspended

sediment transport and hyporheic exchange of permeable gravel bed

rivers

Supervisors: Alberto Bellin and Maurizio Righetti (UnitTn), Kate Heppell and

Geraldene Wharton (QMUL), Daniele Tonina (UoI).

Primary University: University of Trento, (UniTn)

Secondary University: Queen Mary University London, (QMUL)

Associate Partner: University of Idaho, (UoI)

Research Area: A

Description

The ingress of fine sediments into the gravel beds and shallow hyporheic zones of

permeable rivers (termed ‘colmation’ or ‘siltation’) through gravitational settling and

turbulence has been shown to affect both the deposition of fine particulate inorganic and

organic matter in the river bed (Warren et al., 2009), and the nature and temporal

dynamics of surface water and groundwater exchange (Heppell et al., 2009). The

deposition process is in turn influenced by the previously deposited sediment, which

alters the bed roughness and so the turbulence structure of the flow. The scenario

becomes more complicated by the presence of vegetation that can strongly affect the

flow field. Colmation of the river bed can occur due to human activity, for example due to

an increased supply of fine material to the channel through land use change, or a

reduction in river discharge due to abstraction. Naturally occurring processes, such as

glacial silt, can also result in delivery and infiltration of sediment into a gravel river bed.

The consequent reduction in permeability of the river bed can have implications for the

ecology of the river (for example due to a reduction in oxygen supply to spawning

gravels) and for biogeochemical cycling in the shallow hyporheic including the production

and efflux of methane from trapped material (Sanders et al., 2007). The student on this

project will undertake detailed flume experiments at the University of Trento to examine

the effects of colmation on the trapping and retention of fine suspended sediments under

a range of vegetation densities. Tracer experiments in the flume will study the hyporheic

flows associated with different degrees of bed colmation and vegetation cover. This

physically based modelling will be combined with training in fluvial geomorphology and

biogeochemistry at QMUL and empirical field experiments in lowland vegetated rivers in

England in order to establish boundary conditions for the modelling effort, and apply the

findings of the physically based model to the field.

Applicants should have a background in hydraulic engineering, hydrology and

geomorphology and some knowledge of biogeochemistry is desirable but not essential.

References: Heppell C.M., Wharton, G., Cotton, J.A.C., Bass, J.A.B. and Roberts, S.E. (2009) Sediment storage

in the shallow hyporheic of lowland vegetated reaches. Hydrological Processes, 23(15), 2239-2251.

Sanders I., Heppell C.M., Cotton, J.A., Wharton, G., Hildrew, A., Flowers, E.J. and Trimmer, M.

(2007) Emission of methane from chalk streams has potential implications for agricultural

practices. Freshwater Biology, 52 (6), 1176-1186.

Warren, L. L., Wotton, R. S., Wharton, G., Bass, J. A. B. and Cotton, J. A. (2009) The transport of

fine particulate organic matter in vegetated chalk streams. Ecohydrology 2, 480-491.


Climate Sensitivity of the Presena glacier

Supervisors: Alberto Bellin, Simon Carr



Associate Partner:

Research Area: A

Description

This research will focus on the development of coupled numerical mass-balance and ice-

dynamic models to describe the seasonal to decadal behavior of the Presena glacier and

its impact on the discharge of the Vermigliana Creek. Once calibrated, the models will be

used to investigate the potential implications of climate change on the basin, including

the viability of current efforts to reduce net mass-loss by shrouding the glacier during the

summer months. Goals of this study will be therefore to quantify the impact of different

climate change scenarios on the discharge of the Vermigliana creek and hence on

hydropower production.


Bio-morphodynamic evolution of tidal systems

Supervisors: Marco Toffolon and Walter Bertoldi, Kate Spencer



Research Area: C

Description

Estuarine wetlands (e.g. salt marshes, mud flats, lagoons) are complex systems that

provide essential ecosystem services. Predicting the eco-morphodynamic response of

these landforms to e.g. climate change is a challenging issue, which is capturing a

growing attention in the scientific community and in the whole society for its paramount

economic, cultural, and ecological importance.

The goal of this project is to understand the main factors driving the evolution of tidal

systems, focussing on the bio-morphodynamic processes that determine the growth of

the salt marshes through the interaction between the transport and deposition of

sediments and the action of vegetation. The feedbacks between channel network

hydrodynamics and erosional and accretional processes in tidal flats and salt marshes,

like bank erosion and collapse, sediment trapping and biomass production, are mediated

by the spatially varying growth of halophytic vegetation.

The project will consider the Venice lagoon as a case study of primary relevance, taking

advantage from the comparison with other monitored sites in UK. The main activities will

concern the development of a mathematical and/or numerical model, the participation to

field surveys and the recognition of morphological patterns and vegetation dynamics by

image analysis.

Applicants should have good understanding of fluid mechanics and sediment transport,

skills and interest in modelling issues, and be comfortable with differential equations. A

basic knowledge of the ecological aspects will be appreciated.

References - D’Alpaos, A., S. M. Mudd, and L. Carniello (2011), Dynamic response of marshes to perturbations in suspended sediment concentrations and rates of relative sea level rise, J. Geophys. Res., 116,

F04020.

- Fagherazzi, S., et al. (2012), Numerical models of salt marsh evolution: Ecological, geomorphic, and climatic factors, Rev. Geophys., 50, RG1002.

- Kirwan, M. L., and A. Murray (2007), A coupled geomorphic and ecological model of tidal marsh evolution, PNAS, 104(15), 6118–6122.

- Mudd, S. M., A. D’Alpaos, and J. T. Morris (2010), How does vegetation affect sedimentation on

tidal marshes? Investigating particle capture and hydrodynamic controls on biologically mediated sedimentation, J. Geophys. Res., 115, F03029.

- Toffolon, M., and S. Lanzoni (2010), Morphological equilibrium of short channels dissecting the tidal flats of coastal lagoons, J. Geophys. Res., 115, F04036.


Hydroecological processes and nutrients cycling in agricultural ditches

Supervisors: Guido Zolezzi, Alberto Bellin, Kate Heppel, Bruno Maiolini




Research Area: C

Description

Restoration of ecological functions in intensively cultivated agricultural floodplains can

take advantage of irrigation ditch networks whose potential to provide ecosystem

services is often poorly exploited. Ditches communities represent one of the major

biodiversity sources in regulated floodplain areas (Armitage et al., 2003) providing key

ecosystem services which closely depend on their flow regime, like groundwater

recharge, biodiversity control, as well as nutrient attenuation. For example, sediments in

agricultural drainage ditches have been shown to be important sites of nitrate removal

via denitrification (Powell et al., 2010). The proposed research aims to investigate how

relevant physical and biogeochemical aspects of surface – subsurface water interactions

occurring in agricultural floodplains depend on flow regimes in agricultural floodplain

ditches. In particular we will investigate the influence of different flow regimes on

surface-subsurface water and nutrient exchange and nutrient uptake length in

agricultural drainage ditches. The research methods will integrate mathematical

modelling with field observations taken from the case studies of the Rotaliana Plain in

Trento Province (Italy), which represents an ideal site to investigate the system response

to various flow regimes.

References

Armitage P.D., Szoszkiwicz K., Blackburn J.H. and Nesbitt J., 2003. Ditch communities: a major

contributor to floodplain biodiversity. Aquatic Conserv: Mar. Freshw. Ecosyst. 13: 165–185.

Powell K.L. & Bouchard V., 2010. Is denitrification enhanced by the development of natural fluvial

morphology in agricultural headwater ditches? J. North Am. Benth. Soc. 29(2), 761-772.


The role of morphological diversity in improving the health of

hydropower-regulated river systems

Supervisors: Guido Zolezzi, Annunziato Siviglia, Angela Gurnell




Research Area: C

Description

In channelized river systems, giving more room to the river by locally setting back

levees, is increasingly used to enhance the quality and complexity of the physical habitat

through increased, self-formed morphological diversity. Besides channelization, especially

in piedmont areas, river systems are often subject to strong flow regime regulation, with

hydropower operation often playing a major role (Petts and Gurnell, 2005, 2012). These

operation often cause unnatural, rapid changes in streamflow, known as “hydropeaking”,

which may put at risk the success of morphologically-based restoration measures by

affecting spawning habitats of living organisms, hyporeic exchanges of solutes, the river

thermal regime (Zolezzi et al.,2010). However, increased morphological complexity may

also support the provision of refugia for aquatic organisms as river flows vary sharply, by

supporting inundation of hydraulically rough riparian zones and side channels of differing

bed elevation and capacity. The ability of self-formed channels to interact with river flows

to provide refugia depends upon the interplay between discharge, sediment mobilization-

transport-deposition, and vegetation establishment (Gurnell et al., 2012), but little is

known about these interactions in rivers subject to hydropeaking.

The present research aims to investigate the relationship between hydropeaking and

increased morphological diversity in formerly channelized river reaches, with emphasis

on interactions between discharge, sediment and vegetation. The lower Noce River (NE

Italy) will be used as a case study because it offers an excellent array of reaches with

complementary hydro-morphological conditions, up- and downstream of a large

hydropower plant release. Three major research components are foreseen: (1)

reconstruction of the historical morphological evolution of the Noce river segment

through historical maps, aerial images and other remotely sensed data; (2) fieldwork

aimed at characterizing the ecohydraulic and biogeomorphological conditions in the

reach; (3) mathematical modeling of the physical habitat variability in the different sub

reaches. By comparing the Noce study area with other similar regulated river systems,

the proposed research will aim to define optimal and sustainable morphological

improvement measures for rivers with flow regime regulated by hydropower operations.

References

Gurnell, A.M., Bertoldi, W., Corenblit, D. (2012) Changing river channels: the roles of hydrological processes, plants and pioneer fluvial landforms. Earth Sci. Rev, 111 (1-2) 129-141

Petts, G.E. and Gurnell, A.M. (2005) Dams and geomorphology: research progress and new directions. Geomorphology, 71, 27-47.

Petts G.E. and Gurnell, A.M. 2012. Hydrogeomorphic effects of water resources developments.

Treatise in Geomorphology, Volume 13: Geomorphology of Human Disturbances, Hazards and Climate Change, Chapter 8, Elsevier, in press.

Zolezzi, G., Siviglia, A., Toffolon, M., Maiolini, B. 2011. Thermopeaking in Alpine streams: event characterization and time scales. Ecohydrology. 4, 564–576.

Research topic (UF1)

Thermal dynamics in braided river corridors.

Supervisors: Annunziato Siviglia, Guido Zolezzi, Klement Tockner


Secondary University: Freie Universität Berlin (Germany)

Research Area: B

Description

River floodplains are composed of a shifting mosaic of aquatic and terrestrial habitats.

Each habitat type exhibits distinct environmental and ecological properties. Temperature

is a key property driving ecological processes and controlling the composition and

distribution of biota. Thermal dynamics is particularly interesting in braided river

corridors, characterized by strong heterogeneity and diversity (Arscott et al., 2001) and

where thermal patterns dynamics is crucially controlled by surface – subsurface

exchanges, particularly at low flows (Acuna and Tockner, 2008). Mathematical modelling

of thermal dynamics in braided rivers floodplains would result in a major improvements

of the present knowledge on the key controls of such fundamental driver of ecosystem

processes. Existing models have mainly been applied to single thread rivers (Siviglia and

Toro, 2009) while suitable modelling schemes are needed when dealing with complex

morphologies (Stecca et al., 2010). The proposed research aims at (i) developing a

suitable coupling strategy between surface and subsurface flow-transport models, (ii)

applying it to a braided river morphology and at (iii) comparing the model outcomes with

data from real braided river systems.

References

Arscott DB, Tockner K, Ward JV. 2001. Thermal heterogeneity along a braided floodplain river

(Tagliamento River, northeastern Italy). Can J Fish Aquat Sci 58:2359–73.

Acuna V, Tockner K. 2009. Surface–subsurface water exchange rates along alluvial river reaches

control the thermal patterns in an Alpine river network. Freshw Biol 54:306–20.

Siviglia, A., E.F. Toro (2009), The WAF method and splitting procedure for simulating hydro and

thermal peaking waves in open channel flows, Journal of Hydraulic Engineering-ASCE, 135, N8, pp

651-662

Stecca, G., A. Siviglia E.F. Toro (2010), Upwind-biased FORCE schemes with applications to free-

surface shallow flows, Journal of Computational Physics, Volume 229, 18, 6362-6380

Tonolla, D. et al. 2010 Thermal Heterogeneity in River Floodplains. Ecosystems, 13: 727–740.


Environmental impacts of small hydropower plants

Supervisors: Maurizio Righetti (University of Trento), Klement Tockner, Bruno

Maiolini and M. Cristina Bruno (FEM)

Primary University: University of Trento, (UniTn)

Secondary University: Freie Universitat Berlin


Research Area: A

Description

An extensive literature has focused on the impact of hydropower plants, mostly based on

dam effects and hydrological alterations downstream of major power plants. Much less

scientific evidence has been produced to assess the ecological effects of small

hydropower plants (SHP) (Abbasi & Abbasi, 2011).

The general assumption that “small” HPP produce “small” environmental impacts has led

to an increasing demand for building new plants worldwide and particularly in Europe and

more specifically in the Alpine area. This exponential development of new SHP has also

been triggered by the financial incentives and support schemes in place in all European

countries (Alpine Convention, 2001).

SHPs encompass an array of different structural and operational approaches and there is

still no common definition for small, mini or micro plants either if this classification is

based on capacity (kW produced) or on the hydraulic head.

This PhD topic will focus on:

- the characterization of the hydraulic and ecological impacts of different typologies

of SHPs, and

- the finding of production techniques and management practices that attempt to

harmonize the production requests with environmental needing of the stream.

Different typologies of SHPs will be taken into account, from plants located in lowland

rivers (low head, high water volume) to those in mountain streams (high head, low water

volume). For each of these typologies different types of energy production

devices/systems are proposed in literature and by the market (e.g. just considering only

the lowland streams vertical axis turbines, floating low pressure turbines, floating barrels,

transverse horizontal axis turbines or rank of turbines,..), which entails different impacts

both on the hydraulics and on the ecology of the stream.

Representative SHPs will be selected to study the environmental impacts of different

managing and technical/structural schemes. The scientific results will be used to help

defining guidelines for the authorization of new plants and for a more eco-friendly

management of existing ones.

References: Abbasi, T., & Abbasi, S. (2011). Small hydro and the environmental implications of its extensive utilization. Renewable and Sustainable Energy Reviews, 15 (4), 2134-2143 DOI: 10.1016/j.rser.2010.11.050

Hydropower in the Alps focusing on Small Hydropower, 2011. Permanent Secretariat of the Alpine

Convention.


The mechanics of bed-load and grain dispersion in rivers bed

Supervisors: Jens Bölscher, Achim Schulte, Luigi Fraccarollo, Michele Larcher

Primary University: University of Trento, Italy

Secondary University: Freie Universität Berlin, Germany

Associate Partner: Idaho University, Boise, Idaho, USA

Description

In rivers and torrents, bed load consists fundamentally of movements of individual

particles and appears to be a statistically random phenomenon (Einstein, 1937). The

motion of grains is discontinuous, consisting of series of step and rest periods. The grain

movement is affected by the condition of partial or full mobility, by the grainsize

distribution and by the bed morphology.

Characterization of individual particle displacement patterns in streams allows to get

important information about the dispersion processes taking place in the bed, and

provide suggestive links to other type of analyses dealing with the river life, such as the

study of hyphoreic flows, flocculation, infiltration, etc.. The statistics of grain movements,

including their being at rest for even long time period buried in the bed, is important for

the estimation of sediment transport and channel stability. Grain displacement may be

monitored by following marked individual particles and by surveying changes of

morphological patterns (scours and deposits).

The research path will stem from getting experimental and field data (but the doctoral

student may contribute to either type of activity). In laboratory, imaging technique will

be exploited to describe velocity fields of the solid and liquid phases and to track

continuous particle trajectories with high degree of accuracy and statistical reliability

thanks to the measuring devices and the experimental facilities of the Laboratory of

Hydraulics of the University of Trento. Field based activity will employ magnetically

tagged particles, painted stones and advanced topographic tool (stereo-photogrammetry,

terrestrial laser scanner). Bed load data will be complemented with highly detailed

morphological and textural map of selected fluvial reaches, in-channel sediment

availability and channel stability.

One task of the analysis will focus on assessing up to the full scale the theoretical and

experimental results. Potential applications to demanding issues for river engineers, i.e.

the interaction of infrastructure (abutments, hydro-power devices, etc.) or vegetation,

with sediment transport and bed morphology, may be foreseen as further ultimate goal.

This project requires the advisory of scientists applied to the mechanics of sediment

transport, to low and large scale geomorphology and to the hyphoreic convection and

diffusion of substances through the river bed in both live and clear water conditions.

Experimental, modeling and/or numerical skills will be fruitfully spent in the various parts

of this demanding research avenue.

References:

Bradley, D. N., G. E. Tucker, and D. A. Benson (2010), Fractional dispersion in a sand bed river, J.

Geophys. Res., 115, F00A09, doi:10.1029/2009JF001268. Ganti, V., M. Meerschaert, E. Foufoula-Georgiou, E. Viparelli, and G. Parker (2010), Normal and anomalous dispersion of gravel tracers in rivers, J. Geophys. Res., doi:10.1029/2008JF001222.

Research topic (QU1)

Investigating and modelling vegetation – fluvial morphology

interactions: bank erosion and accretion

Supervisors: Walter Bertoldi, Angela Gurnell, Gemma Harvey, Guido Zolezzi

Primary and/or Secondary University: University of Trento and Queen Mary

University of London

Research Area: B

Description

Vegetation dynamics across river margins are governed by hydromorphological processes

that can both promote riparian vegetation growth and disturb and destroy riparian and

aquatic vegetation. Although heavily dependent upon flow regime, vegetation

colonization and growth along river corridors is not an entirely passive process. Once

established, riparian and aquatic plants frequently act as physical ecosystem engineers,

actively driving the development of new landscape elements. In spite of the increasing

recognition of the relevance of this topic, a numerical model that reproduces these

effects decoupling opposite bank evolution is still lacking. The development of such a tool

is fundamental for modelling the evolution of restored river reaches, where vegetation

can play a relevant role in determining the river evolution trajectory.

This research topic aims to investigate sediment and vegetation dynamics at patch and

reach scale in rivers characterised by different energy and flow regimes and to develop a

mathematical model able to reproduce the observed processes. In particular, the

research will focus on the bank related processes, namely i) bank erosion (and the role of

vegetation roots in bank reinforcement); and ii) bank accretion (as a result of fine

sediment deposition and vegetation colonization).

This topic can be developed either from a process analysis or from a mathematical

modelling point of view.

References Bertoldi, W., Gurnell, A.M., Drake, N., 2011. The topographic signature of vegetation development along a braided river: results of a combined analysis of airborne lidar, colour air photographs and

ground measurements. Water Resources Research 47: W06525. Corenblit, D., Tabacchi, E., Steiger, J., Gurnell, A.M., 2007. Reciprocal interactions and

adjustments between fluvial landforms and vegetation dynamics in river corridors: A review of complementary approaches. Earth-Science Reviews 84(1–2): 56–86. Crosato, A., Saleh, M.S., 2011. Numerical study on the effects of floodplain vegetation on river planform style. Earth Surface Processes and Landforms 36(6): 711–720. Perona, P., Molnar, P., Savina, M., Burlando, P., 2009. An observation-based stochastic model for

sediment and vegetation dynamics in the floodplain of an Alpine braided river. Water Resources Research 45: W09418.


Exploring interrelationships between floods and morphodynamics in braided rivers using multispectral satellite data

Supervisors: Alex Henshaw, Gemma Harvey, James Brasington (QMUL) and Walter Bertoldi (UniTN) Primary University: Queen Mary University of London (UK)

Secondary University: University of Trento (Italy)

Research Area: B

Description

Recent research has demonstrated the potential of Landsat Thematic Mapper data in

quantifying interrelated changes in vegetation and channel planform in large braided

rivers (Henshaw et al., in review). The high temporal frequency, broad spatial coverage

and open-access nature of Landsat TM data, suggest that this data source and

methodology has the potential to deliver further process insights. The Landsat archive

now stretches back over 30 years, potentially allowing the influence of flood frequency

and magnitude on channel and island dynamics to be investigated. This project will seek

to utilise multi-spectral satellite images in combination with high resolution aerial

photography, hydrological data and field survey methods (including dendrochronology),

to explore these relationships on a near-natural braided river in north-east Italy; the

Fiume Tagliamento.

References

Henshaw, A.J., Gurnell, A.M., Bertoldi, W., Drake, N.A. (in review) An assessment of the

degree to which Landsat TM data can support the assessment of fluvial dynamics, as

revealed by changes in vegetation extent and channel position, along a large river.

Submitted to Geomorphology


Environmental impacts of hydrodynamic dredging

Supervisors: Kate Spencer (QMUL) and Marco Toffolon (UniTN)

Primary University: Queen Mary University of London (UK)


Research Area: A

Description

Hydrodynamic dredging (including agitation and water injection techniques) involves the

injection of large volumes of water under low pressure into bottom sediment in situ. It is

suitable for fine material including clays and fine silts and breaks the cohesive forces that

bind sediment allowing the sediment to move under the influence of gravity and/or tidal

and river flows. This is an effective and economically attractive dredging technique and

has been used widely in estuaries, ports and harbours, including the Thames Estuary, as

part of a maintenance dredging regime.

Previously, this type of dredging was exempt from licensing as the dredged material did

not leave the water column and was not considered as ‘waste’. However, since April 2011

it has become a licensable activity under the Marine and Coastal Access Act 2009.

Therefore, there is an urgent need to improve our understanding of the potential

environmental impacts of this technique.

This project will focus on understanding the environmental impacts of hydrodynamic

dredging, in particular the impacts on contaminant/nutrient release to the water column,

changes to contaminant bioavailability in bottom sediments and fate of contaminated

sediment in the estuarine and river environment.

Applicants should have a good understanding of aquatic pollution and sediment transport

behavior.

References

Spencer, K.L., Dewhurst, R.E. and Penna, P. 2006. Potential impacts of water injection

dredging on water quality and ecotoxicity in Limehouse Basin, River Thames, SE England,

UK. Chemosphere, 63 (3): 509-521.


Modelling the response of braided rivers and deltas to unsteady

sediment supply.

Supervisors: James Brasington, Alex Hensham and Walter Bertoldi

Primary University: Queen Mary University of London

Secondary University: University of Trento

Research Area: B

Description:

Channel aggradation presents significant river management challenges including the loss

of flood conveyance and an enhanced threat of sudden channel switches or avulsions.

The cause of localized river responses is however, not always easy to identify due to the

discontinuous pattern of sediment transport, storage and remobilization occurring

downstream through the fluvial system. In practice, disentangling local responses due,

for example, to small-scale bar reconfiguration can easily be linked erroneously to

catchment scale changes in sediment supply associated, for example, with deforestation

or mining.

The braided Rees River in Central Otago, NZ offers a well-resourced case study to

investigate the controls on channel bed response associated with a range of sediment

supply processes and provides a useful, rapidly evolving analogue for alpine fluvial

systems worldwide. The Rees is a labile, gravel-bed piedmont braided river that forms

the major left bank tributary of the Rees-Dart delta that discharges into Lake Wakatipu.

High rates of sediment delivery have resulted in and significant bed aggradation along

the lower reaches of the river and progradation of the Rees delta by over 150 m in the

last 80 years. The elevation of the bed near the lakeside township of Glenorchy has

compromised historic flood defences and the community is now at risk of serious

inundation from floods with return periods as low as 1:10.

High rates of sediment supply are common to the rivers of the Southern Alps of NZ and

reflects the combination of intense precipitation forcing, active tectonics and the

reworking of extensive Pleistocene valley floor deposits (Hicks et al., 2008). The Rees

however, appears to have an anomalously high rate of sediment delivery (Wild et al.,

2008) which is hypothesized to be linked to supply from a large mass-movement

catchment, Muddy Creek, in the headwaters. This landslide dominated tributary

catchment, has created a major fan complex that has undergone multiple phases of

incision and reconstruction, which may in turn have led to an oscillating pattern of supply

or transport limited sediment flux conditions in the downstream trunk channel.

This research proposal aims to investigate the consequences of unsteady sediment

supply from this large valley-side sediment store, using a combination of 1d and 2d

numerical simulation modelling. The proposal builds on results from a recent UK NERC

funded project, ReesScan, which has acquired a unique set of digital elevation models

capturing the storm scale morphodynamics of a 3 km braided study reach of the Rees

(Brasington, 2010). This research aims to upscale this study to investigate the dynamics

of large-scale bed pulses or waves, associated with episodic supply from Muddy Creek

along the full 25 km braided reach of the river downstream of the mountain front to the

delta. Modelling will be undertaken using a 1d sediment routing framework similar to

SEDROUTE (Ferguson and Church, 2008), which will in turn be used to parameterize

nested applications of a 2d hydrodynamic model (Delft3d) to investigate the detailed

response of the braided planform under supply limited and transported limited

conditions. An accompanying field campaign will be used to derive detailed digital

elevation models of the lower reaches of the Rees using novel Structure-from-Motion

photogrammetric methods (Neithammer et al., 2011).

Expert guidance will be provided by supervisors Brasington and Bertoldi, who have

extensive experience working on the dynamics of alpine braided rivers in NZ and Europe.

References:

Brasington, J. 2010. From grain to floodplain: hyperscale models of braided rivers. Journal of

Hydraulic Research, 48 (4): 52-53 Suppl. 4 2010.

Ferguson, R. & Church, M. A critical perspective on 1-D modeling of river processes: Gravel load

and aggradation in lower Fraser River. Water Resources Research. 2009;45:W11424

Hicks, D.M. et al., 2003. Sediment estimates: a GIS tool. Water and Atmosphere, NIWA, 11, 26-

27.

Niethammer, U. Et al., 2011. UAV-based remote sensing of the Super-Sauze landslide: Evaluation

and results. Engineering Geology, doi:10.1016/j.enggeo.2011.03.012.


Next generation models for urban flood management.

Supervisors: James Brasington, Alex Henshaw and Walter Bertoldi,Guido Zolezzi



Research Area: C

Over the last decade advances in numerical methods and remote sensing have facilitated

the development of computational hydrodynamic models as key tools for strategic and

operational flood management. Much of this research has focused on applications in

rural or semi-developed floodplains where the details of the built environment can be

largely ignored or parameterized as surface friction. By comparison advances in

predicting the pattern and frequency of inundation in urban areas, where the hazards

posed by flooding are most acute, has received rather less attention. This slow rate of

progress is partly attributable to: a) a lack of high resolution terrain data to parameterize

the topographic boundary condition for applications in large city areas; b) the technical

difficulties of modelling flow through urban areas, including the need for stable solutions

to the governing conservation and momentum equations. However, the emergence of

hyperscale geospatial technologies such as terrestrial laser scanning and structure-from-

motion photogrammetry now offers the opportunity to parameterize the form and

structure of urban floodplains at unprecedented detail (Brasington, 2010). Key

outstanding questions now, are how this wealth of terrain information should be best

used to support urban flood forecasting and what degree of physical complexity is

required of hydrodynamic models to predict urban flood hazards effectively.

Building on recent research (McMillan and Brasington, 2007; McMillan and Brasington

2008, Brasington 2010), this project will investigate the necessary complexity required in

hydraulic models for simulating different forcing scenarios and severities of urban

flooding. Model sensitivity to process complexity, dimensionality, spatial resolution and

solution schemes will be examined using an experimental design incorporating both

‘idealized, synthetic’ and real urban floodplain topographies. These idealized problems

will be used to compare a hierarchy of increasingly complex simulation models (from

simple basin fill models; to zero-inertia solutions; through to shallow water wave solvers)

in a range of different flood scenarios. These will include: 1) pluvial flooding including

overloading of urban drains; 2) flooding from overtopping of embankments; and 3)

catastrophic flooding from overtopping and breaching of defences.

The project will suit a numerate graduate with some experience of programming and a

background in Civil Engineering, Maths, Physics, Computer Science as well as the Earth

Sciences and Physical Geography.

References

Brasington, J. 2010. From grain to floodplain: hyperscale models of braided rivers. Journal of

Hydraulic Research, 48 (4): 52-53 Suppl. 4 2010

McMillan, H.K. and Brasington, J. 2007. Reduced Complexity Strategies for Modelling Urban

Floodplain Inundation, Geomorphology, 90, 226-243.

McMillan, H.K. and Brasington, J. 2008. End-to-end flood forecasting under uncertainty. Water

Resources Research, Doi: 10.1029/2007WR005995


Quantifying the methodological uncertainty in empirical estimates of

gravel sediment transport.

Supervisors: James Brasington, Alex Henshaw and Walter Bertoldi



Research Area: B

Just over a decade ago, Wilcock (2000) suggested provocatively that our ability to

predict the rate of sediment transport through a cross-section of a river could,

optimistically, ‘be placed at order of magnitude or two’! Such uncertainty poses serious

difficulties for the management of sediment resources (e.g., gravel aggregates),

sediment-related hazards (e.g., flood risks associated with bed aggradation) and our

ability to quantify in-stream habitat quality (i.e., for fisheries). More subtlety, the poor

precision of transport estimates also makes the identification of causal links between

upstream catchment modifications (e.g., through land-use or climate change) and the

downstream impacts, such as bed aggradation or degradation and channel instability,

highly hazardous.

While Wilcock’s challenging statement arguably still holds true, the last decade has also

witnessed significant advances in the technological armoury now at the disposal of

geomorphologists and practitioners to address this issue. In particular, the advent of

high precision survey tools, such as airborne and terrestrial lidar, have enabled the

development of precision digital elevation models of fluvial systems, from which transport

rates may be quantified by comparing terrain models before and after floods (Brasington

et al., 2003; Williams et al., 2011; Brasington et al., 2012). Other novel remote sensing

methods include the calculation of bottom-track bias from acoustic Doppler current

profilers which provides direct insight into the magnitude and distributed patterns of bed

velocity (Brasington et al., 2011). In-stream methods have also advanced rapidly, with

radio-tagged tracers capable of sensing their trajectory, bed-mounted impact sensors to

determine the point of incipient transport, and geophones that record an acoustic signal

of the transport itself.

In this project we aim to deploy a battery of methodological approaches to gauge the

uncertainty in empirical transport rates in a small alpine catchment (the Borgn d’Arolla,

Switzerland) where sediment fluxes are managed as part of a regional hydropower

project. This creates a natural laboratory where multiple competent events with

constrained sediment loads are released daily. Using a combination of remote sensing

and in-stream methods, in particular terrestrial laser scanning, radio-particle tracing and

acoustic bottom track observations, this project aims to quantify the basis in

morphologically-derived sediment transport rates that arise from incomplete knowledge

of compensating cycles of cut-and-fill and uncertainties in boundary sediment flux. The

results will have important implications for the practice of sediment transport

measurement in coarse-bedded streams, and will offer novel insights into the links

between sediment flux and the magnitude and frequency of the driving hydrological

events.

References

Brasington, J., Langham, J. and Rumsby, B.T. 2003. Three-dimensional channel sediment budgets:

methodological sensitivity of remote survey methods. Geomorphology, 53, 299-316.

Brasington, J. et al. 2011. Monitoring Braided River Morphodynamics with an Acoustic Doppler

Current Profiler. In, Valentine, E.M. et al. (eds.) Proceedings of the 34th World Congress of the

International Association for Hydro-Environment Research and Engineering: 33rd Hydrology and

Water Resources Symposium and 10th Conference on Hydraulics in Water Engineering, Brisbane.

Engineers-Australia, 3396-3403.

Brasington, J., et al., 2012. Modelling river bed morphology, roughness and surface sedimentology

using high resolution terrestrial laser scanning. Water Resources Research, in press.

Wheaton, J., Brasington, J., Darby, S.E., Sear, D. 2010. Accounting for uncertainty in DEMs from

repeated topographic survey: improved sediment budgets. Earth Surface Processes and

Landforms, 35, 136-156.

Wilcock, P.R. (2001). The flow, the bed, and the transport: Interaction in flume and field. In,

Mosley, P. Et al., Gravel-bed Rivers V. New Zealand Hydrological Society.

Williams, R.D. et al., 2011. Monitoring braided river change using terrestrial laser scanning and

optical bathymetric mapping. In, Smith, M. et al. (eds.) Geomorphological Mapping. Wiley-

Blackwell. 507-532 pp.

Research topic (FU1)

3D riverscapes: An airscape perspective of river landscapes

Supervisors: Klement Tockner, Alexander Sukhodolov, Osvald Fischer, Dino Zardi

Primary University: Freie Universität Berlin (Germany)


Research Area: B

Description

The “airscape” above the water and sediment surface can horizontally and vertically

extent over hundreds of meters and most likely is a very critical but unexploited habitat

for adult aquatic insects as well as a melting pot of aquatic, riparian and terrestrial flying

organisms. Hence, it is a key challenge to develop coupled vegetation-aerodynamic flow

models that predict areas most suitable for resting, mating, and oviposition of flying

insects; an important prerequisite for guiding future restoration and management

strategies.

Interactions of local atmospheric circulations and boundary layer processes over complex

terrain with river/lake environments and ecosystems shall account for the combination of

diurnal atmospheric thermally-driven processes, and in particular local- to micro-scale

flows, occurring over complex terrain (mountains, valleys, basins, etc.) with processes

occurring over and within water bodies (lakes, rivers, marshes, ponds, etc.) that make

the environment of those regions very peculiar.

In this project both field measurements (using air towers and unmanned air vehicles)

along dynamic floodplain rivers (Tagliamento River, Adige River, Italy) and numerical

modelling will be combined to predict the effect of thermally driven atmospheric

processes over complex terrain (valley winds, slope winds, etc.) on the dispersal of flying

insects, dust, and plant seeds.

References

Bitencourt, D. P., and O. C. Acevedo, 2008: Modelling the interaction between a river surface and

the atmosphere at the bottom of a valley. Bound.-Layer Meteor., 129, 309-321.

de Franceschi, M., Zardi, D., Tagliazucca, M., Tampieri, F., 2009, Analysis of second-order

moments in the surface layer turbulence in an Alpine valley. Q. J. R. Met. Soc. 135, 1750–1765

Serafin, S., and D. Zardi, 2010: Daytime development of the convective and mountain boundary

layers under fair weather conditions: a comparison by means of idealized numerical simulations J

Atmos. Sci., 68, 2128-2141.


Critical landscape elements along river corridors

Supervisors: Michael Monaghan, Klement Tockner, Walter Bertoldi

Primary University: Freie Universität Berlin


Associate Partner: Tohoku University

Research Area: C

Description

Regular flooding both destroys and renews much of the physical habitat in the active

corridor of floodplain rivers. Different landscape elements, as side channels, backwaters,

scour pools, vegetated islands provide critical habitats for a wide range of organisms.

Active river corridors are characterised by rapid physical development of these habitats,

leading to rapid changes in their ecological communities. The project will investigate the

morphological structure and the functional ecology of these landscape elements through

field characterisation and remote, automated photographic data. The temporal dynamics

and persistency will be investigated as a function of the flow regime and the spatial

location of the elements. Preferential field site will be the Tagliamento River, Italy, where

two fixed automatic cameras survey the river with an hourly temporal resolution.

References

Bertoldi W., Gurnell A., Surian N., Tockner K., Zanoni L., Ziliani L., Zolezzi G. 2009. Understanding

reference processes: linkages between river flows, sediment dynamics and vegetated landforms along the Tagliamento River, Italy. River Research and Applications, 25, 501-516.

Van der Nat D., Tockner K., Edwards P.J. & Ward J.V. 2003. Habitat change in braided floodplains (Tagliamento, NE-Italy). Freshwater Biology, 48, 1799-1812.


Food web modeling in aquatic systems Supervisors: Christiane Zarfl, Michael Monaghan, Franz Hölker, Guido Zolezzi Primary University: University of Trento

Secondary University: Freie Universität Berlin Associate Partner: IGB

Description

Ecological processes in rivers are strongly influenced by the composition and structure of

aquatic food webs since trophic interactions represent energy and matter conversion. A

food web usually includes all trophic levels from producer to consumer and decomposer.

Nevertheless, even small food webs consisting of only a few species may already show a

complex behaviour. Therefore, investigations in so called mesocosms with artificially

simplified food webs often provide first data on interactions between the different

species. Field experiments can help to complete the ecological picture. A dataset on food

webs in a ditch system will be soon available. But it is also useful to support the

experimental efforts by modelling approaches which allow for a deeper analysis of

interconnections within the food web, parameter sensitivity and the importance of

external, environmental factors like hydraulics and stressors such as artificial light at

night. Therefore, a physical habitat hydraulic model shall be combined with food web

modelling in aquatic systems to analyse mutual feedback interactions. How does the

species’ availability predicted by habitat models change when accounting for food web

modelling? And how is the species composition affected by hydraulic conditions and light

pollution?

References:

Hölker, F., Wolter, C., Perkin, E. K., and Tockner, K. 2010. Light pollution as a

biodiversity threat. Trends in Ecology and Evolution 25: 681-682.

Perkin, E. K., Hölker, F., Richardson, J. S., Sadler, J. P., Wolter, C., and Tockner, K. in

press. The influence of artificial light on freshwater and riparian ecosystems: Questions,

challenges, and perspectives. Ecosphere.


Domesticated freshwaters: structure, function, and biodiversity

Supervisors: Klement Tockner, Guido Zolezzi, Bruno Maiolini

Primary University: Freie Universität Berlin



Research Area: C

Description

Humans have modified natural, and created new, ecosystems to maximize their services

for human use. This domestication of nature is a particularly common phenomenon for

freshwater ecosystems. Today, ditches, artificial ponds, and created wetlands are among

the most abundant freshwaters, however, little information is available to which extent

they play a critical role as habitat for aquatic species and in providing ecosystems

services such as nutrient uptake.

In this project, we will use a range of domesticated ecosystem types, single and in

combination, to investigate their role in maintaining biodiversity and providing ecosystem

services. Furthermore, we will use large-scale field experiments to investigate the role of

altered flow conditions on biodiversity and ecosystem processes, possibly integrated with

mathematical modelling of the key hydrodynamic properties of the investigated systems

such to allow increased quantitative assessments

References:

Kareiva P, Watts S, McDonald R, Boucher T. 2007. Domesticated nature: Shaping landscapes and

ecosystems for human welfare. Science 316: 1866–1869. Steffen, W., Crutzen, P. J., McNeill, J. R. 2007. The Anthropocene: Are humans now overwhelming the great forces of Nature? Ambio 2007, 36, 614–621.

Research topic (FU6) River-floodplain connectivity in a lowland clay river corridor (Prut River, Romania/Moldova): Governing factors of hydrodynamics and

productivity Supervisors: Martin Pusch, Guido Zolezzi

Primary University: Freie Universität Berlin (Germany) Secondary University: University of Trento (Italy) Associate Partner: IGB, Natural History Museum Galati/Romania

(www.cmsngl.ro), GeoEcoMar Constanta/Romania (www.geoecomar.ro), University Iasi/Romania

Description

The dynamics and ecology of lowland rivers meandering in floodplains mostly made up of

clay have hardly been studied so far, even that this river type is very widespread

worldwide e.g. in geologically relative old landscapes and loess areas. Those river

corridors are also most interesting from a theoretical point of view, as they probably

exhibit a low productivity in the river channel due to permanent turbidity of river water,

but a high productivity in the many shallow lakes present in the floodplain. Hence, river-

floodplain connectivity seems to be most crucial for the functioning of these systems, and

thus may relatively easily be studied. Similarly, the river channel exhibits a characteristic

trapezoid cross-section with low habitat diversity, but which significantly increased by

riparian trees falling into the channel from undercut steep river margins, also

accelerating bank erosion rate. Planned research will provide first evidence on the

functioning of hydrodynamic and ecological key processes in a clay river system (Prut,

Romania/Moldava), as meander migration, sediment transport, formation of oxbow and

shallow lakes, habitat formation around fallen trees, lateral hydrological connectivity,

utilization of food resources from floodplain lakes by riverine biota (using stable isotope

technique of food web analysis), and on adaptive timing of life cycles of

riverine biota. For comparison, similar studies will be conducted upstream and

downstream of a large dam present in the Prut (Stânca-Costesti dam) in order to assess

the consequences of such modifications, and their downstream extension. Results will

allow to describe for the first time the coupling of hydrological and ecological processes in

a lowland clay river system, and the implications of the construction of a large dam on

such systems.

References:

Ene, S.A., Teodosiu, C. (2009): Water footprint and challenges for its application to

integrated water resources management in Romania. Environmental Engineering and

Management Journal 8: 1461-1469.

Teodosiu, C., Cojocariu, C., Musteret, C.P., Dascalescu, I.G. Caraene, I. (2009):

Assessment of human and natural impacts over water quality in the Prut River basin,

Romania. Environmental Engineering and Management Journal 8: 1439-1450

Voiculescu, M., Georgescu, L. P., Dragan, S., Timofti, M., Caldararu, A., (2011): Study of

anthropogenic effects on the quality of the Lower Prut River. Journal of Environmental

Protection and Ecology 12: 16-24

Research topic (FQ1)

Remobilization of contaminants out of estuarine sediments Supervisors: Christiane Zarfl, Kate Spencer

Primary University: Freie Universität Berlin Secondary University: Queen Mary, University of London Associated Partner: Leibniz-Institute of Freshwater Ecology and Inland Fisheries

(Berlin) Research Area: C

Description

Predicted climate change and associated sea-level rise may result in the inundation of

low-lying coastal regions with significant loss of coastal habitat and impact on

populations on a global scale. Much of this low-lying land is currently defended and has

been heavily modified by drainage, agriculture and urban development. In Europe,

legislative requirements for sustainable coastal defence and wetland restoration/creation,

and the high economic costs of flood protection have led to the adoption of a range of

management approaches whereby coastal defences are either deliberately removed (e.g.

managed realignment (MR), de-embankment or controlled reduced tide (CRT) schemes),

or no longer maintained to allow tidal inundation of previously protected areas. Once

coastal defences are breached land will be quickly inundated by tidal waters resulting in

the deposition of marine sediment on top of the previous land surface, resulting in

spatially complex sediment structures. Much of this low-lying land may be contaminated

by heavy metals, nutrients and organic contaminants from previous land-use activities

and as yet little is known of the mechanisms by which contaminants may be released to

the overlying water column.

Experimental data on metal concentrations in the sediments and on distribution

behaviour are available and can be combined with mathematical models in order to gain

more insight into the underlying processes of contaminant release. This project will

develop a dynamic model describing the chemical fate of contaminants (metals) in the

structurally complex flooded sediments. This will include an evaluation of concentration

data and parameter values with special focus on an uncertainty analysis to elucidate to

what extent the sea water is exposed to metals remobilized from the sediments.


Ecology of root-endophytic fungi in riparian plants Supervisors: Matthias Rillig, Angela Gurnell

Primary University: Freie Universität Berlin (Germany) Secondary University: Queen Mary University of London (UK) Associate Partner: IGB

Research Area: A

Description

Root endophytes are a diverse and functionally divergent group of fungi. While a lot of

work is focused on arbuscular mycorrhiza, other groups of Eumycota tend to be much

less well studied, even less so in riparian systems. Using trees as the focal plants,

possibly complemented by herbaceous species, this research theme can be addressed in

a number of possible projects. These include studying possible changes in the

composition of root endophyte communities over successional time or in different

ecological settings (e.g., different floodplain contexts, different depths), and the

functional consequences of any such changes. Possible organismic targets are the

enigmatic group of Sebacinales (Basidiomycota with broadly symbiotic traits), dark-

septate endophytes, or parasitic fungi. Such studies could combine molecular ecology

tools with efforts to isolate these fungi and bring them into culture for functional study.

We envision that an observational component at Tagliamento (Italy) or another field site

would be complemented with controlled studies in the laboratory.

References

Bever JD, Dickie IA, Facelli E, Facelli JM, Klironomos JN, Moora M, Rillig MC, Stock WD,

Tibbett M, Zobel M. 2010. Rooting theories of plant ecology in microbial interactions.

Trends in Ecology & Evolution 25: 468-478.

Caruso T, Hempel S, Powell JR, Barto EK, Rillig MC. 2012. Compositional divergence and

convergence in arbuscular mycorrhizal fungal communities. Ecology 93: 1115-1124.

Harner MJ, Mummey DL, Stanford JA, Rillig MC. 2010. Arbuscular mycorrhizal fungi

enhance spotted knapweed growth across a riparian chronosequence. Biological

Invasions 12: 1481-1490.

Jumpponen A, Trappe JM (1998) Dark septate endophytes: a review of facultative

biotrophic root-colonizing fungi. New Phytologist 140: 295–310.

Weiß M, Sýkorová Z, Garnica S, Riess K, Martos F, et al. (2011) Sebacinales everywhere:

Previously overlooked ubiquitous fungal endophytes. PLoS ONE 6(2): e16793.


Hyporheic reactors: Coupling of hydrodynamic and biogeochemical processes in the bed of permeable lowland rivers Supervisors: Jörg Lewandowski, Kate Heppell

Primary University: Freie Universität Berlin (Germany) Secondary University: Queen Mary University of London (UK)

Research Area: B

Description

The transition zone between surface water and groundwater is called hyporheic zone. We

regard it as hydrodynamically driven bioreactor responsible for the impressive self-

purification capacity of streams. Although the role of riparian and hyporheic zones in

nutrient retention has been extensively recognized, the complex coupling of

hydrodynamics and biogeochemistry needs to be further explored in small scale process

studies in order to comprehensively understand and facilitate the management of

nutrient dynamics in disturbed riverine ecosystems (Lewandowski & Nützmann 2010).

There is much heterogeneity in the pathways of water through the hyporheic zone

caused by differences in hydraulic conductivities of the streambed, by upwelling

groundwater, by ripples, by riffles and by pressure differences in water as it moves

around obstacles such as woody debris and macrophyte beds. Although these drivers of

subsurface flow are in principal known (and have been studied in the laboratory and

integrated into models), the resultant flow paths in real river systems have never been

measured systematically in situ. With a novel heat pulse device developed at the IGB

(Lewandowski et al. 2011, Angermann et al. 2012) it is now possible to identify dominant

flow paths and measure flow velocities in the stream bed and hyporheic zones. This PhD

student will determine such pathways in selected river reaches in Germany and the

United Kingdom. After identifying and quantifying the drivers of the hydrodynamic

heterogeneity, the consequences of the heterogeneity for biogeochemistry will be

investigated. Changes in geochemical composition and biogeochemical turnover along the

previously identified flow paths will be studied, with the focus on nitrogen, phosphorus

and carbon fluxes and transformations. Finally, the small scale investigations will be

upscaled based on innovative measurement methods such as distributed temperature

sensing or airborne thermal infrared radiation studies. Thus, we are looking for a PhD

student interested in applying complex hydrodynamic and biogeochemical field methods.

References

Lewandowski, J., Angermann, L., Nützmann, G. and Fleckenstein, J. H. (2011): A heat

pulse technique for the determination of small-scale flow directions and flow velocities in

the streambed of sand-bed streams. Hydrological Processes 25: 3244-3255.

Lewandowski, J. & Nützmann, G. (2010): Nutrient retention and release in a floodplain's

aquifer and in the hyporheic zone of a lowland river. Ecological Engineering 36: 1156-

1166.

Angermann, L., Lewandowski, J., Fleckenstein, J. H. & Nützmann, G. (2012): A 3D

analysis algorithm to improve interpretation of heat pulse sensor results for the

determination of small-scale flow directions and velocities in the hyporheic zone. Journal

of Hydrology, accepted.


Interactive response of macrophytes, invertebrates and fish to changing

hydromorphologic conditions in rivers

Supervisors: Christian Wolter, Alexander Sukhodolov, Angela Gurnell

Primary University: Freie Universität Berlin (Germany) Secondary University: Queen Mary University of London (UK)

Associate Partner: IGB

Research Area: A

Description

Riverine systems are triggered by their hydrographs and stochastic events such as high

floods and droughts. The combination and variability of environmental factors determine

the availability of substrates, structural complexity, depth and width variability as well as

diversity of flow patterns all contributing to complex, diverse habitat patters and thus,

habitat availability for and diversity of aquatic taxa.

River regulation typically cuts the extremes of the hydrograph, reduces discharge

variations and homogenizes flow patterns, all impacting on habitat complexity and

diversity. In general, the reduction of the hydrograph’s extremes is inversely related to

habitat and species diversity, and impacts, for example, on the periodic rejuvenation of

emergent, bank and floodplain vegetation, on bank erosion and bedload transport and

thus, on gravel cleaning, sorting and quality, and on the rejuvenation on habitats in

general by infrequent set back of natural succession during major floods.

With ongoing succession emergent or floating leaved vegetation and organic substrates

become a dominant habitat factor and interactions between aquatic plants, invertebrates

and fish via the food web become the most important structuring factor for aquatic

communities. Accordingly, the primary structuring of, for example, river fish communities

by environmental triggers will decrease as the typical riverine species well adapted to

environmental stochastic fluctuations. If riverine communities are mainly determined by

hydromorphology, while biotic interactions are controlled via the food web by nutrients,

this change to more biologically, food web structured communities might oppose

successful rehabilitation of typical fish assemblages in regulated rivers.

Research hypothesis

Flow regulation moves the primary trigger of environmental stressors as structuring

factors of fluvial communities toward biotic interactions with unforeseeable consequences

for riverine biodiversity.

In regulated rivers, there might be a potential for macrophytes to alter hydrologic

conditions in a way providing hydromorphologic habitat structures both through their

hydraulic effects on velocity and depth patterns, but also ultimately on the adjustment of

channel form through sediment retention and landform building by the macrophytes.


Microplastics in the river system Supervisors: Matthias Rillig, Christiane Zarfl, Simon Carr, Angela Gurnell Primary University: Freie Universität Berlin (Germany)

Secondary University: Queen Mary University of London (UK) Associate Partner: IGB

Research Area: A

Description

Microplastic pollution has been primarily examined in marine systems, but rather limited

knowledge is available on the occurrence of microplastics in rivers, their environmental

fate, and their effects on processes and organisms. Nevertheless, rivers may contribute

significantly as a transport vector for plastics debris into the oceans. In addition, many

processes which were already described for marine environments (e.g. bio-fouling,

sedimentation, fragmentation, uptake by organisms) may happen on a totally different

timescale and to a much higher extent. Therefore, studies could target the abundance of

microplastics, their chemical fate, and/or their effects in the river itself, in the hyporheic

zone or in the riparian soil. Doctoral candidates could develop methods for detection,

could pursue testing of biological effects, or could investigate how much of this material

is accumulating, and where, and the degree to which it is accumulating in different types

of rivers and organisms, rather than being transferred to the sea.

References

Fries E., Zarfl C. (2011): Sorption of polycyclic aromatic hydrocarbons (PAHs) to low and

high density polyethylene (PE). Environ. Sci. Pollut. Res. 19, 1296-1304.

Imhof H. K., Schmid J., Ivleva N. P., Niessner R. Laforsch C. (2012). A novel, highly

efficient method for the quantification of plastic particles in sediments of aquatic

environments. Limnology and Oceanography Methods (in press).

Rillig MC. (2012). Microplastic in terrestrial ecosystems and the soil? Environmental

Science & Technology 46, 6453-6454.

Zarfl C., Fleet D., Fries E., Galgani F., Gerdts G., Hanke G., Matthies M. (2011).

Microplastics in oceans. Marine Pollution Bulletin. 62, 1589-1591.

Zarfl, C., Matthies, M. (2010): Are marine plastic particles transport vectors for organic

pollutants to the Arctic? Marine Pollution Bulletin, 60, 1810-1840.


Airborne and ground-based upscaling of findings on groundwater-surface water interactions Supervisors: Jörg Lewandowski, Gemma Harvey, Hauke Dämpfling, Gunnar

Nützmann Primary University: Freie Universität Berlin (Germany)

Secondary University: Queen Mary University of London (UK) Research Area: B

Description

For the sustainable management of river systems it is essential to understand

groundwater-surface water interactions. Temperature is an important tracer to detect

and quantify groundwater-surface water exchange. On a local scale temperature depth

profiles at the sediment-water interface are a well-established technique to quantify

exfiltration pattern (Schmidt et al. 2006) and active Heat Pulse Sensors (HPS)

(Lewandowski et al. 2011, Angermann et al. 2012) have been recently introduced as a

powerful technique for a detailed process understanding. Though local findings are an

important key for process understanding the overall ecological effect of groundwater-

surface water interactions requires an upscaling of local findings. For that purpose it is

essential to determine the exfiltration pattern with high spatial resolution since most

groundwater-surface water systems are characterized by extreme heterogeneity. For that

purpose ground-based techniques such as Distributed Temperature Sensing (DTS)

(Selker et al. 2006) with a fibre-optic cable, airborne and satellite measurements of

Thermal Infrared Radiation (TIR), and modelling are promising techniques. A major task

of the PhD student will be to develop, improve and apply upscaling techniques. He/She

will conduct DTS measurements, TIR campaigns and modelling exercises. Also, as a

reference and validation of theses findings he/she will apply local techniques such as the

HPS or temperature depth profiles. Furthermore, the ecological impacts of the

groundwater-surface water exchange on local and larger scale should be evaluated and

compared at different field sites based on the findings of the upscaling studies.

References

Angermann, L., Lewandowski, J., Fleckenstein, J. H. and Nützmann, G. (2012): A 3D

analysis algorithm to improve interpretation of heat pulse sensor results for the

determination of small-scale flow directions and velocities in the hyporheic zone. Journal

of Hydrology, accepted.

Lewandowski, J., Angermann, L., Nützmann, G. and Fleckenstein, J. H. (2011): A heat

pulse technique for the determination of small-scale flow directions and flow velocities in

the streambed of sand-bed streams. Hydrological Processes 25: 3244-3255.

Schmidt, C., Bayer-Raich, M. and Schirmer, M. (2006): Characterization of spatial

heterogeneity of groundwater-stream water interactions using multiple depth streambed

temperature measurements at the reach scale. Hydrology and Earth System Sciences 10:

849-859.

Selker, J. S., Thevenaz, L., Huwald, H., Mallet, A., Luxemburg, W., de Giesen, N. V.,

Stejskal, M., Zeman, J., Westhoff, M. and Parlange, M. B. (2006): Distributed fiber-optic

temperature sensing for hydrologic systems. Water Resources Research 42 (12).

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