Beckers, Felix

Dietrich, Daniel R.

Gerbersdorf, Sabine U.

Glaser, Rüdiger

Haun, Stefan

Hofmann, Hilmar

Martin-Creuzburg, Dominik

Noack, Markus

Peeters, Frank

Wieprecht, Silke

English

Hydraulic Engineering Repository

Article, Published VersionBeckers, Felix; Haun, Stefan; Gerbersdorf, Sabine U.; Noack, Markus;Dietrich, Daniel R.; Martin-Creuzburg, Dominik; Peeters, Frank; Hofmann,Hilmar; Glaser, Rüdiger; Wieprecht, SilkeCHARM - Challenges of Reservoir Management - Meetingenvironmental and social requirementsHydrolinkVerfügbar unter/Available at: https://hdl.handle.net/20.500.11970/109414Vorgeschlagene Zitierweise/Suggested citation:Beckers, Felix; Haun, Stefan; Gerbersdorf, Sabine U.; Noack, Markus; Dietrich, Daniel R.;Martin-Creuzburg, Dominik; Peeters, Frank; Hofmann, Hilmar; Glaser, Rüdiger; Wieprecht,Silke (2018): CHARM - Challenges of Reservoir Management - Meeting environmental andsocial requirements. In: Hydrolink 2018/3. Madrid: International Association for Hydro-Environment Engineering and Research (IAHR). S. 80-82. https://iahr.oss-accelerate.aliyuncs.com/library/HydroLink/HydroLink2018_03_Reservoir_Sedimentation.pdf.Standardnutzungsbedingungen/Terms of Use:Die Dokumente in HENRY stehen unter der Creative Commons Lizenz CC BY 4.0, sofern keine abweichendenNutzungsbedingungen getroffen wurden. Damit ist sowohl die kommerzielle Nutzung als auch das Teilen, dieWeiterbearbeitung und Speicherung erlaubt. Das Verwenden und das Bearbeiten stehen unter der Bedingung derNamensnennung. Im Einzelfall kann eine restriktivere Lizenz gelten; dann gelten abweichend von den obigenNutzungsbedingungen die in der dort genannten Lizenz gewährten Nutzungsrechte.Documents in HENRY are made available under the Creative Commons License CC BY 4.0, if no other license isapplicable. Under CC BY 4.0 commercial use and sharing, remixing, transforming, and building upon the materialof the work is permitted. In some cases a different, more restrictive license may apply; if applicable the terms ofthe restrictive license will be binding.80 hydrolink number 3/2018Reservoirs serve a multitude of purposes:hydropower production, drinking and irrigationwater supply, flood retention, and recreation. Thesignificance of reservoirs is highly increasingdue to anthropogenic influences exacerbated byclimate and demographic changes[1]. Theongoing debate about sedimentation in damreservoirs often ignores accompanying sideeffects, which have been insufficiently investi-gated. Apart from a loss in reservoir storagespace due to sedimentation, further processesare involved such as the production of green-house gases and, in many cases, the devel-opment of harmful cyanobacterial blooms[2].One of the reasons is that reservoirs affect thedevelopment of benthic and pelagic bacterialcommunities that may in turn change the bio-chemical processes. Furthermore, the effect ofbiofilm growth in reservoirs is hardly studiedalthough it has considerable implications forsediment transport processes[3]. All these effectscan alter reservoir use and perception, leading topossible conflicts between stakeholders,revealing that not only the construction but alsoreservoir operation and management havesocietal implications. The need for sustainable, economically, sociallyand environmentally acceptable reservoirmanagement strategies is now recognized.Selecting optimal strategies is a challenging taskdue to the complexity and interconnection of theprocesses involved (e.g. hydraulics, sedimenttransport, biochemistry), requiring collaborativeresearch work from complementary disci-plines. The project “CHARM”Objectives and work packagesThe project CHARM (CHAllenges ofReservoir Management, www.charm-bw.de) brings together scientists, withexpertise in engineering, natural andsocial sciences, from three Germanuniversities (Stuttgart, Konstanz andFreiburg) to address, in cross-linkedwork packages, five of the mainissues related to reservoirmanagement: sedimentation,biostabilization, harmful cyanobac-terial blooms, greenhouse gasemissions, and societal implications.The CHARM project seeks toCHARM – CHALLENGES OF RESERVOIR MANAGEMENT – MEETING ENVIRONMENTAL ANDSOCIAL REQUIREMENTSBY FELIX BECKERS, STEFAN HAUN, SABINE U. GERBERSDORF, MARKUS NOACK, DANIEL R. DIETRICH, DOMINIK MARTIN-CREUZBURG, FRANK PEETERS, HILMAR HOFMANN, RÜDIGER GLASER AND SILKE WIEPRECHTThe project CHARM aims at contributing to a better understanding between reservoir management and its impacton the surrounding environment and the reservoir itself. CHARM is a multidisciplinary research project addressingfive fundamental issues of reservoir management: sedimentation, biostabilization, harmful cyanobacterial blooms,greenhouse gas emissions, and societal implications. These issues are tackled through analytical approaches,field monitoring, laboratory experiments and numerical models, thus gaining insights into the involved processesat different scales. The project outcomes will support the development of reservoir management strategies tomeet challenges related to increasing anthropogenic impacts on water bodies and to climate and demographicchanges resulting in altered energy and water demands.Figure 1. Interconnections between major physicochemical and biological processes in reservoirs. These processes and their relations are addressed within CHARM in a holistic approach by five cross-linked work-packages: Sedimentation (WP1), Biostabilization (WP2), Harmful cyanobacterial blooms (WP3), Greenhouse gasemissions (WP4), and Societal implications (WP5).RESERVOIRSEDIMENTATION81hydrolink number 3/2018also an attractive recreation destination(“Nationalpark Schwarzwald”), with a surfacearea of approximately 60 ha, a maximum depthof 65 m (average depth of 21.8 m), and avolume of about 14.4 Mm³ at maximumoperation level. An intensive data acquisition,involving stationary, continuous, and spatiotem-poral resolved measurements, was conductedto record a comprehensive abiotic and bioticdataset. A mooring station equipped with anAcoustic Current Doppler Profiler (ADCP),thermistors (T), optodes (O2, CO2) and pHsensors was installed to obtain long-term, verti-cally resolved datasets. Autonomouslymeasuring funnels were installed along thethalweg and at the river mouth of the reservoir tomeasure the ebullition of CH4. During regularlyconducted field campaigns, the spatial distri-bution of CH4 and CO2 flux above the air-waterinterface was measured by floating chambers incombination with automatic CO2 sensors, orwith a portable gas sensor. In addition, localprofiles of temperature, conductivity, O2, pH,CO2, turbidity, and Chl-a pigments weremeasured with different probes. The fieldcampaigns were complemented by measure-ments of nutrient concentration (P, N), alkalinity,phyto- and zooplankton composition, collectionof water for experiments, sediment sampling(grab and core sampling) at selected locations,and the collection of resting stages ofcyanobacteria and Daphnia in the pelagial,profundal, and benthic sediments of thereservoir. Sediments in the SBT consist of mainly siltymaterial with a decreasing grain size along thethalweg towards the dam (Figure 4). Theextracted sediment cores are characterized by alow bulk density (0.9 to 1.3 g/cm³) that can bedue to large water and gas contents as well as ahigh organic content (7 to 14%). The laboratoryexperiments of sediment deposit stabilitysuggest that erosion should be initiated at lowshear stresses. Moreover, they emphasize thatthe erosion behavior can only be described bytaking into account both cohesive and adhesiveforces. In 2016, water samples from the SBT(oligotrophic, slightly acidic) were collected tocultivate biofilm in the laboratory. The reservoirwater was circulated in six independent,identical flumes. While the biofilm growth wasstudied in relation to varying flow conditions, theeffects on species composition, metabolicactivity, and functionality, here the biostabi-lization potential, were studied over a period ofseveral weeks. The results illustrated the highpotential of biofilm to stabilize fine sediments(up to 15 times as compared to the control) andrevealed a strong link of this biofilm function tothe nutrient and flow condition. Altogether, thesefirst investigations indicate the impact ofmicroorganisms on sediment deposit stabilityand dynamics in reservoirs.The investigation of cyanobacterial bloomsrevealed that the blooms in the SBT primarilyconsist of Anabaena species and that thecomposition of the zooplankton communitychanges during the formation of a cyanobac-terial bloom, i.e. the abundance of largeaddress complex interconnections (Figure 1).For instance, the sediment deposit stabilitydepends on several abiotic and biotic param-eters that include both cohesiveness andadhesiveness. Gas produced in sedimentsimpacts the atmospheric emissions anddepends on the oxygen concentration in thedeep water that is affected by reservoiroperation[4]. The nutrient inputs impact the closeinteractions between zooplankton, phyto-plankton, and cyanobacterial recruitment andinitiate or boost the development of algaeblooms. Algae blooms are important for socio-economic weighting, evaluation, and devel-opment of a balanced and sustainable reservoirmanagement. Thus, the project requires consid-erable inter- and transdisciplinary research toreveal these interconnections, which is accom-plished by close collaboration between scien-tists working across different fields. Study areas and reservoirsResearch is conducted in three reservoirs(Figures 2-3): Schwarzenbach Reservoir(hydropower and recreation), Kleine KinzigReservoir (drinking water supply) and reservoirGroßer Brombachsee (low water regulation andrecreation). Joint field measurements providedata which are used (i) to correlate sedimentstability with sediment parameters and green-house gas emissions, (ii) as background infor-mation for biofilm cultivation, (iii) for theassessment of temporal development of thephyto- and zooplankton community consideringtoxin production and release, and finally (iv) as abasis for hydrodynamic, sediment transport,and water quality modelling. Some aspects areinvestigated under controlled conditions in thelaboratory, such as the vertical sediment stabilityover depth using novel erosion detectionmethods[5], the stabilizing capacity of biofilmsby conducting manipulative experiments andadhesion measurements with a magneticdevice[6], and the formation and toxicology ofcyanobacterial blooms using mesocosm experi-ments[7]. To evaluate the social environment ofthe reservoir systems and the associatedconflict potential, methodical approaches (e.g.constellation analyses, surveys, interviews,composite programming[8]) are used. Inaddition, a Collaborative Research Environment(CRE) will be prepared.The Schwarzenbach Reservoir caseIn 2016 and 2017, the focus of the project wason the Schwarzenbach Reservoir (SBT), usedfor hydropower production since 1926(pumped-storage operation). The reservoir isIAHRFigure 3. Kleine Kinzig Reservoir used for drinking water supply (left) and reservoir Großer Brombachseeinitially constructed for low water regulation but also used for local recreation (right).Figure 2. Schwarzenbach Reservoir at maximum operation level (left) and during water level lowering (right)RESERVOIRSEDIMENTATION82 hydrolink number 3/2018zooplankton species decreases (Daphnialongispina) while smaller species increase(Ceriodaphnia sp. and Bosmina sp.). Reasonsfor this shift in the zooplankton speciescommunity, caused by the formation ofcyanobacteria, are currently investigated inlaboratory and mesocosm experiments.Based on the obtained dataset from the fieldcampaigns, greenhouse gas emission andstorage can be linked to hydrodynamic condi-tions, sediments, and phytoplankton devel-opment. In the SBT, the diffusive CH4-fluxesfrom sediments are comparatively low (Figure4). However, a significant correlation betweenebullition and daily water level fluctuations canbe seen[9]. In general, the release of methanebubbles through pumped storage operationscontributes considerably to the total emission ofCH4. The O2 concentration in the deep waterdecreases less with pumping compared to nopumping operation. As a result of the high O2concentration, the CH4 accumulation in thedeep water is reduced. Hence, the pumpedstorage operation indirectly contributes to thefact that CH4 emissions of stored methane arecomparatively low in the SBT during the autumnoverturn.The combination of the gained insights onbiological, chemical and geological processesand the management procedures help to under-stand the reservoir as a system embedded in itsimmediate social surrounding. This knowledgecan be used to mitigate societal implications.For example, the formation of cyanobacterialblooms has notably increased since 2002 and islikely connected to a change in the reservoiroperation. The combined relationships betweenmajor effects and the potential impairment ofreservoir functionality are considered by allinvolved experts, to jointly derive sustainablemanagement strategies that are designed toattenuate or avoid conflicting interests. First lessonsThe first results gained within the CHARMproject reveal that there are complex interde-pendencies between the processes of sedimen-tation, biostabilization, harmful cyanobacterialblooms, greenhouse gas emissions, and theirsocietal implications. These interdependenciescan only be addressed by transdisciplinaryresearch among the involved disciplines. It isrecommended to take into consideration bio-chemical parameters (e.g. biostabilization) ininvestigating sediment stability in reservoirs. Thereservoir management also impacts green-house gas emissions, showing a clear corre-lation between ebullition and water level fluctua-tions. This knowledge is of significant impor-tance for drawdown periods or pumpingoperations, which further affect the nutrient influxand the distribution of dissolved substancesand algae in the reservoir that may support theformation of cyanobacterial blooms. The lattermay lead to conflicts between stakeholders,especially when the reservoir is used for otherpurposes (e.g. recreation). After the completion and evaluation of theintegrated data collection, it is intended toimplement the obtained information in anumerical model that takes into accountphysical and biological processes, therebycontributing to a better understanding ofsediment dynamics, distribution and release ofgreenhouse gases, and water quality in reser-voirs. The model can be used to simulate andpredict the effects of reservoir managementscenarios to derive sustainable strategies, meetmultiple interests, and increase societalacceptance of reservoirs. Conclusively, reser-voirs with different purposes and management(Kleine Kinzig, Großer Brombachsee) will beconsidered within the next two years in order toensure the transferability of the results. nREFERENCES[1] Zarfl, C., Lumsdon, A.E., Berlekamp, J., Tydecks, L., Tockner, K.(2015). A global boom in hydropower dam construction. AquaticSciences 77, 161–170. https://doi.org/10.1007/s00027-014-0377-0[2] Leigh, C., Burford, M.A., Roberts, D.T., Udy, J.W. (2010). Predictingthe vulnerability of reservoirs to poor water quality and cyanobac-terial blooms. Water Research 44, 4487–4496.https://doi.org/10.1016/j.watres.2010.06.016[3] Schmidt, H., Thom, M., Wieprecht, S., Manz, W., Gerbersdorf, S.U., (2018). The effect of light intensity and shear stress on micro-bial biostabilization and the community composition of naturalbiofilms. Res Reports Biol. 8:1–16.doi:10.2147/RRB.S145282.[4] Encinas Fernández, J. M., Peeters, F., Hofmann, H. (2014)Importance of the autumn overturn and anoxic conditions in thehypolimnion for the annual methane emissions from a temperatelake. Environ. Sci. Technol. 48 (13): 7297-7304,doi:10.1021/es4056164.[5] Noack, M., Schmid, G., Beckers, F., Haun, S., Wieprecht, S. (2018).PHOTOSED - PHOTOgrammetric Sediment Erosion Detection.Geosciences 2018, 8, 243; doi:10.3390/geosciences8070243.[6] Gerbersdorf, S.U., Wieprecht, S., Thom, M., Paterson, D.M.,Scheffler, M. (2018). New insights into MagPI: a promising tool todetermine adhesive capacity of biofilm on the mesoscale.Biofouling, in press,https://doi.org/10.1080/08927014.2018.1476971.[7] Dietrich, D. (2005). Risk cyanobacterial toxins: occurrence,ecology, detection, toxicology, and health effects assessment.Toxicology and Applied Pharmacology 203, 191.https://doi.org/10.1016/j.taap.2005.02.003[8] Bárdossy, A., Duckstein, L. (1992): Analysis of a Karstic AquiferManagement Problem by Fuzzy Composite Programming. In:Journal of the American Water Resources Association.https://doi.org/10.1111/j.1752-1688.1992.tb03154.x.[9] Encinas Fernandez, J., Peeters, F., Hofmann, H. (2016). On themethane paradox: Transport from shallow water zones rather thanin situ methanogenesis is the major source of CH4 in the opensurface water of lakes. J. Geophys. Res. Biogeo. 121: 2717–2726.Figure 4. Spatial distribution of the dissolved CH4 concentration in the Schwarzenbach Reservoir andsurface sediment composition along the thalweg (data recorded in 2016). Black circles: CH4 samplingstations; White triangles: ebullition funnels; Black squares: sediment sampling locations; White cross:mooring station. The map shows the reservoir at maximum operation water level, whereas the blackcontour line indicates the minimum operation level.The CHARM-Team iThe project CHARM“CHAllenges of ReservoirManagement - MeetingEnvironmental and SocialRequirements” is part of theWater Research NetworkBaden-Württemberg. It is funded by the Ministry ofScience, Research and Arts of the federal state ofBaden-Württemberg, Germany. Under the lead of Prof. Dr.-Ing. Silke Wieprecht, 17 researchers and various students contribute toachieve the project goals.For further information about CHARM: www.charm-bw.deRESERVOIRSEDIMENTATION

CHARM - Challenges of Reservoir Management - Meeting environmental and social requirements

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CHARM - Challenges of Reservoir Management - Meeting environmental and social requirements

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