title: Modeller subjectivity and calibration impacts on hydrological model applications: an event-based comparison for a road-adjacent catchment in south-east Norway.
abstract: Identifying a 'best' performing hydrologic model in a practical sense is difficult due to the potential influences of modeller subjectivity on, for example, calibration procedure and parameter selection. This is especially true for model applications at the event scale where the prevailing catchment conditions can have a strong impact on apparent model performance and suitability. In this study, two lumped models (CoupModel and HBV) and two physically-based distributed models (LISEM and MIKE SHE) were applied to a small catchment upstream of a road in south-eastern Norway. All models were calibrated to a single event representing typical winter conditions in the region and then applied to various other winter events to investigate the potential impact of calibration period and methodology on model performance. Peak flow and event-based hydrographs were simulated differently by all models leading to differences in apparent model performance under this application. In this case-study, the lumped models appeared to be better suited for hydrological events that differed from the calibration event (i.e., events when runoff was generated from rain on non-frozen soils rather than from rain and snowmelt on frozen soil) while the more physical-based approaches appeared better suited during snowmelt and frozen soil conditions more consistent with the event-specific calibration. This was due to the combination of variations in subsurface conditions over the eight events considered, the subsequent ability of the models to represent the impact of the conditions (particularly when subsurface conditions varied greatly from the calibration event), and the different approaches adopted to calibrate the models. These results indicate that hydrologic models may not only need to be selected on a case-by-case basis but also have their performance evaluated on an application-by-application basis since how a model is applied can be equally important as inherent model structure.
authors.affiliation: Department of Land and Water Resources, Royal Institute of Technology/KTH, SE-10044 Stockholm, Sweden; Department of Physical Geography and Quaternary Geology, Stockholm University, SE-106 91 Stockholm, Sweden. Electronic address: zahrak@kth.se.
authors.forename: Zahra
authors.initials: Z
authors.lastname: Kalantari
authors.affiliation: Department of Physical Geography and Quaternary Geology, Stockholm University, SE-106 91 Stockholm, Sweden. Electronic address: steve.lyon@natgeo.su.se.
authors.forename: Steve W
authors.initials: SW
authors.lastname: Lyon
authors.affiliation: Department of Land and Water Resources, Royal Institute of Technology/KTH, SE-10044 Stockholm, Sweden. Electronic address: pej@kth.se.
authors.forename: Per-Erik
authors.initials: PE
authors.lastname: Jansson
authors.affiliation: Norwegian Institute for Agricultural and Environmental Research, Bioforsk, Soil and Environment Division, NO-1432 Ås, Norway. Electronic address: jannes.stolte@bioforsk.no.
authors.forename: Jannes
authors.initials: J
authors.lastname: Stolte
authors.affiliation: Department of Plant and Environmental Sciences, Norwegian University of Life Sciences, NO-1432 Ås, Norway. Electronic address: helen.french@umb.no.
authors.forename: Helen K
authors.initials: HK
authors.lastname: French
authors.affiliation: Department of Land and Water Resources, Royal Institute of Technology/KTH, SE-10044 Stockholm, Sweden. Electronic address: lennart.folkeson@vti.se.
authors.forename: Lennart
authors.initials: L
authors.lastname: Folkeson
authors.affiliation: DHI Sverige AB, SE-111 29 Stockholm, Sweden. Electronic address: mona.sassner@dhi.se.
authors.forename: Mona
authors.initials: M
authors.lastname: Sassner
mesh_terms: D002138:Calibration; D004784:Environmental Monitoring / Q000379:methods; D062070:Hydrology; D008956:Models, Chemical; D009664:Norway; D011891:Rain; D012621:Seasons; D012987:Soil / Q000737:chemistry; D014867:Water / Q000032:analysis*; D014872:Water Movements
chemical_list: D012987:Soil; D014867:Water
keywords: Extreme weather events; Hydrological model; Road drainage; Road infrastructure; Runoff