Department Surface Waters - Research and Management

array(2 items)
   publications => '23901,22089,19168,14433,15354,14467,7763,4446' (45 chars)
   libraryUrl => '' (0 chars)

array(8 items)
   0 => Snowflake\Publications\Domain\Model\Publicationprototypepersistent entity (uid=23901, pid=124)
      originalId => protected23901 (integer)
      authors => protected'Bärenbold, F.; Kipfer, R.; Schmid, M.' (53 chars)
      title => protected'Dynamic modelling provides new insights into development and maintenance of 
         Lake Kivu's density stratification' (110 chars)
      journal => protected'Environmental Modelling and Software' (36 chars)
      year => protected2022 (integer)
      volume => protected147 (integer)
      issue => protected'' (0 chars)
      startpage => protected'105251 (15 pp.)' (15 chars)
      otherpage => protected'' (0 chars)
      categories => protected'Lake Kivu; Simstrat-AED2; 1d modelling; gas accumulation; hydrothermal groun
         dwater' (82 chars)
      description => protected'Lake Kivu is a 485 m deep, Central-East African rift lake with huge amounts 
         of carbon dioxide and methane dissolved in its stably stratified deep waters
         . In view of future large-scale methane extraction, one-dimensional numerica
         l modelling is an important and computationally inexpensive tool to analyze 
         the evolution of stratification and the content of gases in Lake Kivu. For t
         his purpose, we coupled the physical lake model Simstrat to the biogeochemic
         al library AED2. Compared to an earlier modelling approach, this coupled app
         roach offers several key improvements, most importantly the dynamic evaluati
         on of mixing processes over the whole water column, including a parameteriza
         tion for double-diffusive transport, and the density-dependent stratificatio
         n of groundwater inflows. The coupled model successfully reproduces today's 
         near steady-state of Lake Kivu, and we demonstrate that a complete mixing ev
         ent ∼2000 years ago is compatible with today's physical and biogeochemical
          state.' (995 chars)
      serialnumber => protected'1364-8152' (9 chars)
      doi => protected'10.1016/j.envsoft.2021.105251' (29 chars)
      uid => protected23901 (integer)
      _localizedUid => protected23901 (integer)modified
      _languageUid => protectedNULL
      _versionedUid => protected23901 (integer)modified
      pid => protected124 (integer)
   1 => Snowflake\Publications\Domain\Model\Publicationprototypepersistent entity (uid=22089, pid=124)
      originalId => protected22089 (integer)
      authors => protected'Råman Vinnå, L.; Medhaug, I.; Schmid, M.; Bouffard, D.' (76 chars)
      title => protected'The vulnerability of lakes to climate change along an altitudinal gradient' (74 chars)
      journal => protected'Communications Earth & Environment' (34 chars)
      year => protected2021 (integer)
      volume => protected2 (integer)
      issue => protected'' (0 chars)
      startpage => protected'35 (10 pp.)' (11 chars)
      otherpage => protected'' (0 chars)
      categories => protected'' (0 chars)
      description => protected'Studies of future 21<sup>st</sup> century climate warming in lakes along alt
         itudinal gradients have been partially obscured by local atmospheric phenome
         na unresolved in climate models. Here we forced the physical lake model Sims
         trat with locally downscaled climate models under three future scenarios to 
         investigate the impact on 29 Swiss lakes, varying in size along an altitudin
         al gradient. Results from the worst-case scenario project substantial change
          at the end of the century in duration of ice-cover at mid to high altitude 
         (−2 to −107 days), stratification duration (winter −17 to −84 days, 
         summer −2 to 73 days), while lower and especially mid altitude (present da
         y mean annual air temperature from 9 °C to 3 °C) dimictic lakes risk s
         hift to monomictic regimes (seven out of the eight lakes). Analysis further 
         indicates that for many lakes shifts in mixing regime can be avoided by adhe
         ring to the most stringent scenario.' (948 chars)
      serialnumber => protected'' (0 chars)
      doi => protected'10.1038/s43247-021-00106-w' (26 chars)
      uid => protected22089 (integer)
      _localizedUid => protected22089 (integer)modified
      _languageUid => protectedNULL
      _versionedUid => protected22089 (integer)modified
      pid => protected124 (integer)
   2 => Snowflake\Publications\Domain\Model\Publicationprototypepersistent entity (uid=19168, pid=124)
      originalId => protected19168 (integer)
      authors => protected'Gaudard,&nbsp;A.; Råman Vinnå,&nbsp;L.; Bärenbold,&nbsp;F.; Schmid,&nbsp;
         M.; Bouffard,&nbsp;D.' (97 chars)
      title => protected'Toward an open access to high-frequency lake modeling and statistics data fo
         r scientists and practitioners - the case of Swiss lakes using Simstrat v2.1' (152 chars)
      journal => protected'Geoscientific Model Development' (31 chars)
      year => protected2019 (integer)
      volume => protected12 (integer)
      issue => protected'9' (1 chars)
      startpage => protected'3955' (4 chars)
      otherpage => protected'3974' (4 chars)
      categories => protected'' (0 chars)
      description => protected'One-dimensional hydrodynamic models are nowadays widely recognized as key to
         ols for lake studies. They offer the possibility to analyze processes at hig
         h frequency, here referring to hourly timescales, to investigate scenarios a
         nd test hypotheses. Yet, simulation outputs are mainly used by the modellers
          themselves and often not easily reachable for the outside community. We hav
         e developed an open-access web-based platform for visualization and promotio
         n of easy access to lake model output data updated in near-real time (http:/
         /simstrat.eawag.ch, last access: 29 August 2019). This platform was develo
         ped for 54 lakes in Switzerland with potential for adaptation to other regio
         ns or at global scale using appropriate forcing input data. The benefit of t
         his data platform is practically illustrated with two examples. First, we sh
         ow that the output data allows for assessing the long-term effects of past c
         limate change on the thermal structure of a lake. The study confirms the nee
         d to not only evaluate changes in all atmospheric forcing but also changes i
         n the watershed or throughflow heat energy and changes in light penetration 
         to assess the lake thermal structure. Then, we show how the data platform ca
         n be used to study and compare the role of episodic strong wind events for d
         ifferent lakes on a regional scale and especially how their thermal structur
         e is temporarily destabilized. With this open-access data platform, we demon
         strate a new path forward for scientists and practitioners promoting a cross
          exchange of expertise through openly sharing in situ and model data.' (1589 chars)
      serialnumber => protected'1991-959X' (9 chars)
      doi => protected'10.5194/gmd-12-3955-2019' (24 chars)
      uid => protected19168 (integer)
      _localizedUid => protected19168 (integer)modified
      _languageUid => protectedNULL
      _versionedUid => protected19168 (integer)modified
      pid => protected124 (integer)
   3 => Snowflake\Publications\Domain\Model\Publicationprototypepersistent entity (uid=14433, pid=124)
      originalId => protected14433 (integer)
      authors => protected'Schmid,&nbsp;M.; Ostrovsky,&nbsp;I.; McGinnis,&nbsp;D.&nbsp;F.' (62 chars)
      title => protected'Role of gas ebullition in the methane budget of a deep subtropical lake: Wha
         t can we learn from process-based modeling?' (119 chars)
      journal => protected'Limnology and Oceanography' (26 chars)
      year => protected2017 (integer)
      volume => protected62 (integer)
      issue => protected'6' (1 chars)
      startpage => protected'2674' (4 chars)
      otherpage => protected'2698' (4 chars)
      categories => protected'' (0 chars)
      description => protected'We analyzed the processes affecting the methane (CH<sub>4</sub>) budget in L
         ake Kinneret, a deep subtropical lake, using a suite of three models: (1) a 
         bubble model to determine the fate of CH<sub>4</sub> bubbles released from t
         he sediment; (2) the one-dimensional physical lake model Simstrat to calcula
         te the mixing dynamics; and (3) a biogeochemical model implemented in Aquasi
         m to quantify the CH<sub>4</sub> sources and sinks. The key pathways modeled
          include diffusive and bubble release of CH<sub>4</sub> from the sediment, a
         erobic CH<sub>4</sub> oxidation, and atmospheric gas exchange. The temporal 
         and spatial dynamics of dissolved CH<sub>4</sub> concentrations observed in 
         the lake during 3 years could be well represented by the combined models. Re
         markably, the relative contributions of ebullition and diffusive transport t
         o the accumulation of CH<sub>4</sub> in the hypolimnion during the stratifie
         d period could not be accurately constrained based only on the observed evol
         ution of CH<sub>4</sub> concentrations in the water column. Importantly, how
         ever, our analysis showed that most (∼99%) of the CH<sub>4</sub> supplied 
         to the water column by bubble dissolution and diffusive transport from the s
         ediment is aerobically oxidized, whereas a substantial fraction (∼60%) of 
         the sediment-released bubble CH<sub>4</sub> is directly transported to the a
         tmosphere. Ebullition is thus responsible for the bulk of the emissions from
          Lake Kinneret to the atmosphere. Therefore, as in all freshwaters, ebulliti
         on quantification is crucial for accurately assessing CH<sub>4</sub> emissio
         ns to the atmosphere. This task remains challenging due to high spatio-tempo
         ral variability, but combining in situ measurements with a process-based mod
         eling can help to better constrain flux estimates.' (1798 chars)
      serialnumber => protected'0024-3590' (9 chars)
      doi => protected'10.1002/lno.10598' (17 chars)
      uid => protected14433 (integer)
      _localizedUid => protected14433 (integer)modified
      _languageUid => protectedNULL
      _versionedUid => protected14433 (integer)modified
      pid => protected124 (integer)
   4 => Snowflake\Publications\Domain\Model\Publicationprototypepersistent entity (uid=15354, pid=124)
      originalId => protected15354 (integer)
      authors => protected'Gaudard,&nbsp;A.; Schwefel,&nbsp;R.; Vinnå,&nbsp;L.&nbsp;R.; Schmid,&nbsp;M
         .; Wüest,&nbsp;A.; Bouffard,&nbsp;D.' (113 chars)
      title => protected'Optimizing the parameterization of deep mixing and internal seiches in one-d
         imensional hydrodynamic models: a case study with Simstrat v1.3' (139 chars)
      journal => protected'Geoscientific Model Development' (31 chars)
      year => protected2017 (integer)
      volume => protected10 (integer)
      issue => protected'9' (1 chars)
      startpage => protected'3411' (4 chars)
      otherpage => protected'3423' (4 chars)
      categories => protected'' (0 chars)
      description => protected'This paper presents an improvement of a one-dimensional lake hydrodynamic mo
         del (Simstrat) to characterize the vertical thermal structure of deep lakes.
          Using physically based arguments, we refine the transfer of wind energy to 
         basin-scale internal waves (BSIWs). We consider the properties of the basin,
          the characteristics of the wind time series and the stability of the water 
         column to filter and thereby optimize the magnitude of wind energy transferr
         ed to BSIWs. We show that this filtering procedure can significantly improve
          the accuracy of modelled temperatures, especially in the deep water of lake
         s such as Lake Geneva, for which the root mean square error between observed
          and simulated temperatures was reduced by up to 40 %. The modification, t
         ested on four different lakes, increases model accuracy and contributes to a
          significantly better reproduction of seasonal deep convective mixing, a fun
         damental parameter for biogeochemical processes such as oxygen depletion. It
          also improves modelling over long time series for the purpose of climate ch
         ange studies.' (1077 chars)
      serialnumber => protected'1991-959X' (9 chars)
      doi => protected'10.5194/gmd-10-3411-2017' (24 chars)
      uid => protected15354 (integer)
      _localizedUid => protected15354 (integer)modified
      _languageUid => protectedNULL
      _versionedUid => protected15354 (integer)modified
      pid => protected124 (integer)
   5 => Snowflake\Publications\Domain\Model\Publicationprototypepersistent entity (uid=14467, pid=124)
      originalId => protected14467 (integer)
      authors => protected'Råman Vinnå,&nbsp;L.; Wüest,&nbsp;A.; Bouffard,&nbsp;D.' (58 chars)
      title => protected'Physical effects of thermal pollution in lakes' (46 chars)
      journal => protected'Water Resources Research' (24 chars)
      year => protected2017 (integer)
      volume => protected53 (integer)
      issue => protected'5' (1 chars)
      startpage => protected'3968' (4 chars)
      otherpage => protected'3987' (4 chars)
      categories => protected'nuclear power plant; thermal pollution; residence time; hydrodynamic modelin
         g; climate change' (93 chars)
      description => protected'Anthropogenic heat emissions into inland waters influence water temperature 
         and affect stratification, heat and nutrient fluxes, deep water renewal, and
          biota. Given the increased thermal stress on these systems by growing cooli
         ng demands of riparian/coastal infrastructures in combination with climate w
         arming, the question arises on how to best monitor and manage these systems.
          In this study, we investigate local and system-wide physical effects on the
          medium-sized perialpine Lake Biel (Switzerland), influenced by point-source
          cooling water emission from an upstream nuclear power plant (heat emission 
         ∼700 MW, ∼18 W m<sup>−2</sup> lake wide). We use one-dimensional (SIMS
         TRAT) and three-dimensional (Delft3D-Flow) hydrodynamic numerical simulation
         s and provide model resolution guidelines for future studies of thermal poll
         ution. The effects on Lake Biel by the emitted excess heat are summarized as
         : (i) clear seasonal trend in temperature increase, locally up to 3.4°C and
          system-wide volume mean ∼0.3°C, which corresponds to one decade of regio
         nal surface water climate warming; (ii) the majority of supplied thermal pol
         lution (∼60%) leaves this short residence time (∼58 days) system via the
          main outlet, whereas the remaining heat exits to the atmosphere; (iii) incr
         eased length of stratified period due to the stabilizing effects of addition
         al heat; (iv) system-wide effects such as warmer temperature, prolonged stra
         tified period, and river-caused epilimnion flushing are resolved by both mod
         els whereas local raised temperature and river short circuiting was only ide
         ntifiable with the three-dimensional model approach. This model-based method
          provides an ideal tool to assess man-made impacts on lakes and their downst
         ream outflows.' (1762 chars)
      serialnumber => protected'0043-1397' (9 chars)
      doi => protected'10.1002/2016WR019686' (20 chars)
      uid => protected14467 (integer)
      _localizedUid => protected14467 (integer)modified
      _languageUid => protectedNULL
      _versionedUid => protected14467 (integer)modified
      pid => protected124 (integer)
   6 => Snowflake\Publications\Domain\Model\Publicationprototypepersistent entity (uid=7763, pid=124)
      originalId => protected7763 (integer)
      authors => protected'Fink,&nbsp;G.; Schmid,&nbsp;M.; Wüest,&nbsp;A.' (47 chars)
      title => protected'Large lakes as sources and sinks of anthropogenic heat: capacities and limit
         s' (77 chars)
      journal => protected'Water Resources Research' (24 chars)
      year => protected2014 (integer)
      volume => protected50 (integer)
      issue => protected'9' (1 chars)
      startpage => protected'7285' (4 chars)
      otherpage => protected'7301' (4 chars)
      categories => protected'' (0 chars)
      description => protected'The goal of reducing carbon fuel and thereby saving energy will increase the
          use of lake water for heating and cooling of riparian infrastructures. This
          raises the question of which heat use designs meet the ecological and techn
         ical requirements for lakes, particularly in regard to climate warming. Thus
         , this study explores heat use effects on the temperature and stratification
          of a large, deep, temperate lake by applying the one-dimensional k-epsilon 
         model SIMSTRAT to various forcing scenarios. Several design parameters, such
          as extraction and discharge depth, and their effects were assessed. Additio
         nally, 21st century climate projections were used to evaluate the effects of
          climate change relative to those of heat use. Generally, the study showed o
         nly minor effects for a realistic heat demand of ±2 W m<SUP>−2</SUP> quit
         e independent of the heat extraction/discharge modes. Mean water temperature
          changed less than ±0.2°C as long as there was no discharge into the deepe
         st layers. Water extraction and discharge at the surface had the least therm
         al influence. To relate to climate change, heat use was scaled up to +85 W m
         <SUP>−2</SUP>. Resultant simulations showed that such (unrealistic) anthro
         pogenic, lake-based “<I>thermal pollution</I>” would have a comparable i
         nfluence to that of climate change. Conversely, heat extraction could damp o
         r even compensate climate-induced warming. The present study concludes that 
         (i) there are minor effects on water temperatures, stratification, and seaso
         nal mixing due to heat use of up to ±2 W m<SUP>−2</SUP> and (ii) those in
         fluences are insignificant relative to the expected climate change.' (1663 chars)
      serialnumber => protected'0043-1397' (9 chars)
      doi => protected'10.1002/2014WR015509' (20 chars)
      uid => protected7763 (integer)
      _localizedUid => protected7763 (integer)modified
      _languageUid => protectedNULL
      _versionedUid => protected7763 (integer)modified
      pid => protected124 (integer)
   7 => Snowflake\Publications\Domain\Model\Publicationprototypepersistent entity (uid=4446, pid=124)
      originalId => protected4446 (integer)
      authors => protected'Goudsmit,&nbsp;G.&nbsp;-H.; Burchard,&nbsp;H.; Peeters,&nbsp;F.; Wüest,&nbs
         p;A.' (80 chars)
      title => protected'Application of k-ϵ turbulence models to enclosed basins: the role of intern
         al seiches' (86 chars)
      journal => protected'Journal of Geophysical Research: Oceans' (39 chars)
      year => protected2002 (integer)
      volume => protected107 (integer)
      issue => protected'C12' (3 chars)
      startpage => protected'3230 (13 pp.)' (13 chars)
      otherpage => protected'' (0 chars)
      categories => protected'lake; turbulence model; seiche; stratification; simulation; turbulence kinet
         ic energy' (85 chars)
      description => protected'A numerical model was developed for the prediction of the density stratifica
         tion of lakes and reservoirs. It combines a buoyancy-extended <em>k</em>-ϵ 
         model with a seiche excitation and damping model to predict the diffusivity 
         below the surface mixed layer. The model was applied to predict the seasonal
          development of temperature stratification and turbulent diffusivity in two 
         medium-sized lakes over time periods ranging from 3 weeks to 2 years. Depend
         ing on the type of boundary condition for temperature, two or three model pa
         rameters were optimized to calibrate the model. The agreement between the si
         mulated and the observed temperature distributions is excellent, in particul
         ar, if lake surface temperatures were prescribed as surface boundary conditi
         on instead of temperature gradients derived from heat fluxes. Comparison of 
         different model variants revealed that inclusion of horizontal pressure grad
         ients and/or stability functions is not required to provide good agreement b
         etween model results and data. With the aid of uncertainty analysis it is sh
         own that the depth of the mixed surface layer during the stratified period c
         ould be predicted accurately within ±1 m. The sensitivity of the model to s
         everal parameters is discussed.' (1247 chars)
      serialnumber => protected'2169-9275' (9 chars)
      doi => protected'10.1029/2001JC000954' (20 chars)
      uid => protected4446 (integer)
      _localizedUid => protected4446 (integer)modified
      _languageUid => protectedNULL
      _versionedUid => protected4446 (integer)modified
      pid => protected124 (integer)