Hydro

Known issues

SOBEK 2.12 issues

SOBEK FLOW 1D Open Water (Rural 1DFLOW)


Unsolved	Unexpected model behavior using the HORZDISPER process in WAQ 1D. This message/warning is only for users of the HORZDISPER process and the Dutch SOBEK Tewor users. The HORZDISPER process determines the horizontal dispersion depending on the flow characteristics. This formulation can lead to extreme dispersion coefficients resulting in extreme mixing. It is strongly advised to check the dispersion determined by the HORZDISPER process, or to disable the process in Settings. Note that SOBEK includes several standard water quality subsets. The HORZDISPER process is included in the two “Tewor2003” subsets. Theses subsets are designed for standard Dutch “Tewor” calculations. Other standard subsets do not use the HORZDISPER process.
Unsolved	Negative lateral discharge is not always taken into account during simulation An issue has been determined where a negative lateral discharge is set to zero during a model simulation while there is enough water available at that location. This is due to an incorrect check on available volume of water. It is possible that no lateral discharge is withdrawn on nodes where a negative lateral discharge has been set by the user. Background info: A large withdrawal of water (negative lateral discharge) can cause problems when the amount of outflowing water is larger than the storage available in a calculation point. To avoid these problems, the SOBEK Flow engine reduces the time step temporarily when the outflowing water volume is larger than half the available volume (safety factor) in the calculation point. The time step is set to a value that allows a withdrawal of half the available volume in one time step. If the time step resulting from this action is smaller than 0.01 second, the lateral withdrawal is set to zero. This issue will be solved in SOBEK 2.12.004.
Unsolved	Incorrect flow results in case of bifurcation using Flow - Linkage Node. The Flow - Linkage Node option has not been designed for modelling bifurcations. This option is available to easily add and remove tributaries or affluents for modelling flows into a parent river. Thus, for inflows from rivers with discharges of a magnitude lower than the parent river. As many users requested the functionality to interpolate Flow - Cross Section data across a Flow - Connection Node, similar to the functionality of the Flow - Linkage Node, we are happy to announce this functionality will be available in the upcoming release. This issue will be solved in SOBEK 2.12.004 with a new functionality to allow interpolation of Cross-Section data over a "Flow - Connection Node".
Solved in 2.12.003	Unexpected loss of water might occur above the highest point in the Y-Z and Asymmetrical trapezium profiles (2.12.002 only) Adding Y-Z profiles and Asymmetrical trapezium profiles in SOBEK version 2.12.002 might result in a 'st 1' being written in the profile.def file. This setting for the st (Storage Type) keyword is considered deprecated functionality. It is not recommended to use this option in current SOBEK versions. When "st 1" is used for a Y-Z or Asymmetrical Trapezium profile, water above the highest point in the cross-sectional profile is considered as loss (i.e will leave the model as a kind of lateral outflow). Nowadays it is advised to use only the setting 'st 0'. Using this setting means that the width at the highest point in the cross-sectional profile is applied in situations where the computed water level is higher than the highest point in the cross-sectional profile. This means that there is no loss of water. Users can change this behaviour by opening the file "profile.def" file present in every case directory, and replacing any 'st 1' value by 'st 0'. A new patch, called SOBEK 2.12.002a , no longer writes 'st 1' into the profile.def file for newly created Y-Z or Asymmetrical Trapezium profiles. Also, when SOBEK 2.12.002a encounters 'st 1' in the profile.def file for a Y-Z or Asymmetrical Trapezium definition, the calculation is terminated and a message is written in the sobek.log file. This patch is available for download. This solution will also be available in the upcoming SOBEK 2.12.003 version.
Solved in 2.12.003	"Incorrect results in case Y-Z profiles and/or Asymmetrical trapezium profiles are used in combination with Bos & Bijkerk friction type anywhere in a model". In case the Bos & Bijkerk friction type is used anywhere in a model schematisation, the computational core should not switch off the vertically segmented conveyance method applied for all Y-Z profiles and Asymmetrical trapezium profiles, even if another friction formulation is used at such profile. It is strongly advised not to use the Bos & Bijkerk friction type in combination with Y-Z profiles and Asymmetrical trapezium profiles. This issue will be solved in SOBEK 2.12.003.