start:hype_model_description:hype_routing
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start:hype_model_description:hype_routing [2020/01/23 08:14] cpers [Common rivers processes] |
start:hype_model_description:hype_routing [2020/02/05 10:22] cpers [Basic assumptions] |
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| The two lake types are separate classes. The lake classes have characteristics such as land use and soil type, which are defined together with the other classes' characteristics (in GeoClass.txt). Precipitation, atmospheric deposition and evaporation of rivers and lakes are calculated first, while river flow and inflow, transformation processes and the outflow of the lakes is calculated thereafter. Lakes and rivers are calculated in the model’s routing part after all classes are calculated for the subbasin. | The two lake types are separate classes. The lake classes have characteristics such as land use and soil type, which are defined together with the other classes' characteristics (in GeoClass.txt). Precipitation, atmospheric deposition and evaporation of rivers and lakes are calculated first, while river flow and inflow, transformation processes and the outflow of the lakes is calculated thereafter. Lakes and rivers are calculated in the model’s routing part after all classes are calculated for the subbasin. | ||
| - | An outlet lake can be part of a larger lake. It is then called a lake basin. Lake basins are olakes in nearby subbasins. Outlet lakes that are not lake basins are referred to below as simple outlet lakes. | + | An outlet lake can be part of a larger lake. It is then called a lake basin. Lake basins are olakes in nearby subbasins. |
| - | A simple outlet lake has a threshold. The outflow ends if the water level drops below the threshold. Lake mean depth below the threshold is specified in GeoData.txt or LakeData.txt as //lake_depth// in meters. Lake depth can also be set by parameters, i.e general parameter //gldepo// or olake region parameter //olldepth//. The threshold is also the the water level of the lake at the start of a simulation. The current water level is denoted as //wlm// in Fig. 2. For printing, the outlet lake water level (output variable //wcom//) is calculated in meters and you can set a reference level (//w0ref//) in LakeData.txt to get the same height system as any observations of the lake's water level. The lake’s //w0ref// is added to the water level above the threshold. HYPE assumes the lake has vertical sides in the calculations, thus the observed variation may be larger than the simulated variation. It is therefore possible to adjust the output //wcom// (and //wcav//) for the actual amplitude of the regulation volume (//wamp//). This will make the simulated and recorded water stage comparable below the threshold for a regulated lake. | + | A simple outlet lake has a threshold. The outflow ends if the water level drops below the threshold. Lake mean depth below the threshold is specified in GeoData.txt or LakeData.txt as //lake_depth// in meters. Lake depth can also be set by parameters, i.e general parameter //gldepo// or olake region parameter //olldepth//. The threshold is also the the water level of the lake at the start of a simulation. The current water level is denoted as //wlm// in Fig. 2. For printing, the outlet lake water level (output variable //wcom//) is calculated in meters and you can set a reference level (//w0ref//) in LakeData.txt to get the same height system as any observations of the lake's water level. The lake’s //w0ref// is added to the water level above the threshold. A regulated lake (dam) has two thresholds. One, same as for a simple lake, is used for spill, and one lower threshold were outflow ends completely. The distance between the thresholds are determined by the regulation volume. HYPE assumes the lake/dam has vertical sides in the calculations, thus the observed variation in water level may be larger than the simulated variation. It is therefore possible to adjust the output //wcom// (and //wcav//) for the actual amplitude of the regulation volume (//wamp//). This will make the simulated and recorded water stage comparable below the threshold for a regulated lake. |
| |{{:start:hype_model_description:outletlakewithvariables2.png?400|}}| | |{{:start:hype_model_description:outletlakewithvariables2.png?400|}}| | ||
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| ==== Initalisation of lake volume ==== | ==== Initalisation of lake volume ==== | ||
| - | Unless a starting state is given from a file, the lakes start the simulation filled with water to their outflow threshold. That means for ilakes and simple olakes a water level equal to //lake_depth//. Dams are filled to the dam's maximum elevation (equal to //lake_depth//), except for flood control dams which are initializied with an empty regulation volume. | + | Unless a starting state is given from a file, the lakes start the simulation filled with water to their outflow threshold. That means for most lakes a water level equal to //lake_depth//. Dams are filled to the dam's maximum elevation (equal to //lake_depth//), except for flood control dams which are initializied with an empty regulation volume. |
| For lakes with outflow determined by a rating curve, the water level of the lake will be higher than the outflow threshold level. The equilibrium level will depend on the size of the inflow and the outflow rating curve parameters. Depending on the residence time of water in the lake it may take time for this level to be established, and until then the outflow of the lake will be simulated lower than it should be. Thus a spin-up time is needed for a model simulation. | For lakes with outflow determined by a rating curve, the water level of the lake will be higher than the outflow threshold level. The equilibrium level will depend on the size of the inflow and the outflow rating curve parameters. Depending on the residence time of water in the lake it may take time for this level to be established, and until then the outflow of the lake will be simulated lower than it should be. Thus a spin-up time is needed for a model simulation. | ||
start/hype_model_description/hype_routing.txt · Last modified: 2024/01/25 11:37 (external edit)
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