@article{HoettgesArnoldRouve1992,
  author    = {H{\"o}ttges, J{\"o}rg and Arnold, Uwe and Rouv{\´e}, Gerhard},
  title     = {Profiles of Mixing Coefficient in Compound Open Channel},
  series = {Flow modeling and turbulence measurements : [... a collection of lectures and papers presented at the Fourth International Symposium on Refined Flow Modelling and Turbulence Measurements held in Wuhan, People's Republic of China, on September 20-23, 1990]},
  journal   = {Flow modeling and turbulence measurements : [... a collection of lectures and papers presented at the Fourth International Symposium on Refined Flow Modelling and Turbulence Measurements held in Wuhan, People's Republic of China, on September 20-23, 1990]},
  publisher = {Hemisphere Publ. Corp.},
  address   = {Washington, DC [u.a.]},
  isbn      = {1-56032-209-8},
  pages     = {XVII, 773 S. : graph. Darst.},
  year      = {1992},
  language  = {en}
}
@article{Hoettges2017,
  author    = {H{\"o}ttges, J{\"o}rg},
  title     = {QKan - Management of drainage system data with QGIS},
  series = {Free and Open Source Software for Geospatial (FOSS4G) Conference Proceedings},
  volume    = {17},
  journal   = {Free and Open Source Software for Geospatial (FOSS4G) Conference Proceedings},
  number    = {Article 13},
  pages     = {95 -- 100},
  year      = {2017},
  language  = {en}
}
@article{BienerSasse1993,
  author    = {Biener, Ernst and Sasse, T.},
  title     = {Quality improvements in the construction of multilayer covers},
  series = {G{\´e}ologie et confinement des d{\´e}chets toxiques : actes du symposium international, 8 - 11 juin 1993 / GEOCONFINE 93, Montpellier, France. R{\´e}d. Marcel Arnould},
  journal   = {G{\´e}ologie et confinement des d{\´e}chets toxiques : actes du symposium international, 8 - 11 juin 1993 / GEOCONFINE 93, Montpellier, France. R{\´e}d. Marcel Arnould},
  publisher = {Balkema},
  address   = {Rotterdam [u.a.]},
  isbn      = {90-5410-330-2},
  pages     = {309 -- 312},
  year      = {1993},
  language  = {en}
}
@article{BungValero2018,
  author    = {Bung, Daniel B. and Valero, Daniel},
  title     = {Re-aeration on stepped spillways with special consideration of entrained and entrapped air},
  series = {Geosciences},
  volume    = {8},
  journal   = {Geosciences},
  number    = {9},
  publisher = {MDPI},
  address   = {Basel},
  issn      = {2076-3263},
  pages     = {Article number 333},
  year      = {2018},
  abstract  = {As with most high-velocity free-surface flows, stepped spillway flows become self-aerated when the drop height exceeds a critical value. Due to the step-induced macro-roughness, the flow field becomes more turbulent than on a similar smooth-invert chute. For this reason, cascades are oftentimes used as re-aeration structures in wastewater treatment. However, for stepped spillways as flood release structures downstream of deoxygenated reservoirs, gas transfer is also of crucial significance to meet ecological requirements. Prediction of mass transfer velocities becomes challenging, as the flow regime differs from typical previously studied flow conditions. In this paper, detailed air-water flow measurements are conducted on stepped spillway models with different geometry, with the aim to estimate the specific air-water interface. Re-aeration performances are determined by applying the absorption method. In contrast to earlier studies, the aerated water body is considered a continuous mixture up to a level where 75\% air concentration is reached. Above this level, a homogenous surface wave field is considered, which is found to significantly affect the total air-water interface available for mass transfer. Geometrical characteristics of these surface waves are obtained from high-speed camera investigations. The results show that both the mean air concentration and the mean flow velocity have influence on the mass transfer. Finally, an empirical relationship for the mass transfer on stepped spillway models is proposed.},
  language  = {en}
}
@article{ValeroBung2018,
  author    = {Valero, Daniel and Bung, Daniel B.},
  title     = {Reformulating self-aeration in hydraulic structures: Turbulent growth of free surface perturbations leading to air entrainment},
  series = {International Journal of Multiphase Flow},
  volume    = {100},
  journal   = {International Journal of Multiphase Flow},
  publisher = {Elsevier},
  address   = {Amsterdam},
  issn      = {0301-9322},
  doi       = {10.1016/j.ijmultiphaseflow.2017.12.011},
  pages     = {127 -- 142},
  year      = {2018},
  abstract  = {A new formulation for the prediction of free surface dynamics related to the turbulence occurring nearby is proposed. This formulation, altogether with a breakup criterion, can be used to compute the inception of self-aeration in high velocity flows like those occurring in hydraulic structures. Assuming a simple perturbation geometry, a kinematic and a non-linear momentum-based dynamic equation are formulated and forces acting on a control volume are approximated. Limiting steepness is proposed as an adequate breakup criterion. Role of the velocity fluctuations normal to the free surface is shown to be the main turbulence quantity related to self-aeration and the role of the scales contained in the turbulence spectrum are depicted. Surface tension force is integrated accounting for large displacements by using differential geometry for the curvature estimation. Gravity and pressure effects are also contemplated in the proposed formulation. The obtained equations can be numerically integrated for each wavelength, hence resulting in different growth rates and allowing computation of the free surface roughness wavelength distribution. Application to a prototype scale spillway (at the Aviemore dam) revealed that most unstable wavelength was close to the Taylor lengthscale. Amplitude distributions have been also obtained observing different scaling for perturbations stabilized by gravity or surface tension. The proposed theoretical framework represents a new conceptualization of self-aeration which explains the characteristic rough surface at the non-aerated region as well as other previous experimental observations which remained unresolved for several decades.},
  language  = {en}
}
@article{Biener1985,
  author    = {Biener, Ernst},
  title     = {Rehabilitation of old gravity dams},
  series = {[Transactions] : proceedings of fifteenth international congress on large dams ; 24 - 28 Juin 1985, Lausanne, Suisse = Quinzieme Congres International des Grands Barrages. - Bd. 4},
  journal   = {[Transactions] : proceedings of fifteenth international congress on large dams ; 24 - 28 Juin 1985, Lausanne, Suisse = Quinzieme Congres International des Grands Barrages. - Bd. 4},
  publisher = {Intern. Commission on Large Dams},
  address   = {Paris},
  pages     = {Q 59, R.2, S. 21 -- 23},
  year      = {1985},
  language  = {en}
}
@article{KirsteinMuellerWaleckiMingersetal.2012,
  author    = {Kirstein, Simon and M{\"u}ller, Karsten and Walecki-Mingers, Mark and Deserno, Thomas M.},
  title     = {Robust adaptive flow line detection in sewer pipes},
  series = {Automation in construction},
  journal   = {Automation in construction},
  number    = {21},
  publisher = {Elsevier},
  address   = {Amsterdam},
  issn      = {1872-7891 (E-Journal) ; 0926-5805 (Print)},
  doi       = {10.1016/j.autcon.2011.05.009},
  pages     = {24 -- 31},
  year      = {2012},
  abstract  = {As part of a novel approach to automatic sewer inspection, this paper presents a robust algorithm for automatic flow line detection. A large image repository is obtained from about 50,000 m sewers to represent the high variability of real world sewer systems. Automatic image processing combines Canny edge detection, Hough transform for straight lines and cost minimization using Dijkstra's shortest path algorithm. Assuming that flow lines are mostly smoothly connected horizontal structures, piecewise flow line delineation is reduced to a process of selecting adjacent line candidates. Costs are derived from the gap between adjacent candidates and their reliability. A single parameter α enables simple control of the algorithm. The detected flow line may precisely follow the segmented edges (α = 0.0) or minimize gaps at joints (α = 1.0). Both, manual and ground truth-based analysis indicate that α = 0.8 is optimal and independent of the sewer's material. The algorithm forms an essential step to further automation of sewer inspection.},
  language  = {en}
}
@article{ValeroChansonBung2020,
  author    = {Valero, Daniel and Chanson, Hubert and Bung, Daniel B.},
  title     = {Robust estimators for free surface turbulence characterization: A stepped spillway application},
  series = {Flow Measurement and Instrumentation},
  volume    = {76},
  journal   = {Flow Measurement and Instrumentation},
  number    = {Art. 101809},
  publisher = {Elsevier},
  address   = {Amsterdam},
  issn      = {0955-5986},
  doi       = {10.1016/j.flowmeasinst.2020.101809},
  year      = {2020},
  abstract  = {Robust estimators are parameters insensitive to the presence of outliers. However, they presume the shape of the variables' probability density function. This study exemplifies the sensitivity of turbulent quantities to the use of classic and robust estimators and the presence of outliers in turbulent flow depth time series. A wide range of turbulence quantities was analysed based upon a stepped spillway case study, using flow depths sampled with Acoustic Displacement Meters as the flow variable of interest. The studied parameters include: the expected free surface level, the expected fluctuation intensity, the depth skewness, the autocorrelation timescales, the vertical velocity fluctuation intensity, the perturbations celerity and the one-dimensional free surface turbulence spectrum. Three levels of filtering were utilised prior to applying classic and robust estimators, showing that comparable robustness can be obtained either using classic estimators together with an intermediate filtering technique or using robust estimators instead, without any filtering technique.},
  language  = {en}
}
@article{ValeroChansonBung2019,
  author    = {Valero, Daniel and Chanson, Hubert and Bung, Daniel B.},
  title     = {Robust estimators for turbulence properties assessment},
  pages     = {1 -- 24},
  year      = {2019},
  language  = {en}
}
@article{ValeroBung2016,
  author    = {Valero, Daniel and Bung, Daniel B.},
  title     = {Sensitivity of turbulent Schmidt number and turbulence model to simulations of jets in crossflow},
  series = {Environmental Modelling and Software},
  volume    = {82},
  journal   = {Environmental Modelling and Software},
  publisher = {Elsevier},
  address   = {Amsterdam},
  issn      = {1364-8152 (electronic)},
  doi       = {10.1016/j.envsoft.2016.04.030},
  pages     = {218 -- 228},
  year      = {2016},
  abstract  = {Environmental discharges have been traditionally designed by means of cost-intensive and time-consuming experimental studies. Some extensively validated models based on an integral approach have been often employed for water quality problems, as recommended by USEPA (i.e.: CORMIX). In this study, FLOW-3D is employed for a full 3D RANS modelling of two turbulent jet-to-crossflow cases, including free surface jet impingement. Results are compared to both physical modelling and CORMIX to better assess model performance. Turbulence measurements have been collected for a better understanding of turbulent diffusion's parameter sensitivity. Although both studied models are generally able to reproduce jet trajectory, jet separation downstream of the impingement has been reproduced only by RANS modelling. Additionally, concentrations are better reproduced by FLOW-3D when the proper turbulent Schmidt number is used. This study provides a recommendation on the selection of the turbulence model and the turbulent Schmidt number for future outfall structures design studies.},
  language  = {en}
}