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start:hype_model_description:hype_land [2020/04/29 10:15]
cpers [Soil temperature and frozen soil]
start:hype_model_description:hype_land [2024/02/21 10:05] (current)
cpers [Overview of flow paths]
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 ====== Land routines ====== ​ ====== Land routines ====== ​
  
-This section explains the computations in the land routines of HYPE. If you want an interactive overview of how the routines simulates runoff please have a look at [[http://​vattenweb.smhi.se/​hypeexplorer|the HYPE Runoff Explorer]].+This section explains the computations in the land routines of HYPE. 
  
 ===== Basic assumptions ===== ===== Basic assumptions =====
Line 31: Line 31:
 ==== Overview of flow paths ==== ==== Overview of flow paths ====
  
-|{{:​start:​hype_model_description:​overviewflowpaths.png?​600|}}|+|{{:​start:​hype_model_description:​HYPE_box_picture_v3_soilclasses.png?​600|}}|
 |Figure 5: Illustration of flowpaths in the soil in the HYPE model.| |Figure 5: Illustration of flowpaths in the soil in the HYPE model.|
 +
 +
 +==== Recharge - discharge model ====
 +
 +In the basic model of HYPE the land classes are calculated in parallell and have no interaction with each other. The recharge - discharge model is a modeloption to introduce a crude representation of flow of water between classes within a subbasin. Some classes are chosen to represent recharge area, and other classes represent discharge area within the subbasin. The glacier class and surface water classes cannot be included in the recharge-discharge model. Another limitation is that the model does not work with classes using rootzone leakage and travel-time soilmodels as recharge or discharge classes.
 +
 +In this model a part of the (originally calculated) runoff from the recharge classes are redirected to the discharge classes where it is spread equally over their area. This means that the model is sensitive to the relative fraction of area of recharge and discharge classes in the subbasin. The water is added to the bottom soillayers of the discharge classes and can there cause upwelling of water to above soil layers. The actual runoff of the recharge classes are reduced from the originally calculated value with the part going to the discharge area. The discharge classes will have a larger runoff due to the incoming water. ​
 +
 +The part of the runoff from a recharge class that will go the the discharge class(es) are determined by a fraction given per class, and a maximum catchment area of the discharge classes. The latter is determined by a factor (general parameter //​wetdisca//​) of the the area of the the discharge classes, a maximum ratio between recharge area and discharge area.
 +
  
 ==== Diagnostic variables ==== ==== Diagnostic variables ====
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 <m> frostdepth = frost * sfrost * soiltemp * (fc+wp) / soil </m> <m> frostdepth = frost * sfrost * soiltemp * (fc+wp) / soil </m>
  
-There are two parameters in order to be able to choose if you want the frost depth to be land use dependent or soil dependent. The not used parameter ​is set to one.+There are two parameters in order to be able to choose if you want the frost depth to be land use dependent or soil dependent. The parameter for the not used dependence ​is set to one.
  
 ==== Links to file reference ==== ==== Links to file reference ====
Line 84: Line 94:
  
 ==== Snow melt ==== ==== Snow melt ====
-For the simplest snow model, snow melt is calculated by temperature index. Snow melting occurs when the temperature is greater than a threshold temperature. ​The amount ​of snow (//snow// in mm) that melts (//melt//) depends on the snowmelt parameter //cmlt//, threshold temperature parameter //​ttmp// ​and air temperature (//temp//). Additionally snow melt may be adjusted by the snow cover. The parameter //fsceff// determine how large effect the snow cover scaling should have, between zero and one.+For the simplest snow model, snow melt is calculated by temperature index. Snow melting occurs ​proportionally to temperature, ​when the temperature is greater than a threshold temperature. ​Other options are to considers the effect ​of radiation ​and snow cover. ​
  
-Alternative ​snowmelt models ​exist, but are not fully described here yet. + 
 +The alternative ​snowmelt models are not fully described here yet. 
  
 === Model 0 (default) === === Model 0 (default) ===
-Temperature ​index model, with or without snow cover scaling, ​described above.+The default model is a temperature ​index model, with or without snow cover scaling. Snow melting occurs when the temperature is greater than a threshold temperature. The potential snow that melts (//pmelt//) depends on the snowmelt parameter //cmlt//threshold temperature parameter //ttmp// and air temperature (//temp//). Additionally snow melt may be adjusted by the snow cover (//​effcover//​). The parameter //fsceff// determine how large effect the snow cover scaling should have, between zero and one. The actual snow melt is limited by the amount of snow (//snow// in mm)
  
 <m> effcover = 1-(1-fsceff)*snowcov </m> <m> effcover = 1-(1-fsceff)*snowcov </m>
  
-<​m> ​melt MIN(cmlt*(temp-ttmp),​snow)*effcover ​</m>+<​m> ​pmelt cm*(temp-ttmp)*effcover </​m>​ 
 + 
 +<m> cm = cmlt*(1+cmltcorr) </​m>​ 
 + 
 +<m> melt = MIN(pmelt,snow) </m>
  
-The parameters //cmlt// and //ttmp// are related to land use, while //fsceff// is general.+The parameters //cmlt// and //ttmp// are related to land use and cmltcorr depend on parameter region, while //fsceff// is general.
  
 === Model 2 === === Model 2 ===
-Temperature ​and radiation index model, with or without snow cover scaling. The temperature index snow melt is calculated the same way as the default model. In addition ​radiation ​snow melt is calculated from shortwave radiation and albedo of the snow. +the second model is a temperature ​and radiation index model, with or without snow cover scaling. The temperature index potential ​snow melt is calculated the same way as the default model (//pmelt//). In addition ​potential ​snow melt by radiation index (//​rpmelt//​) ​is calculated from shortwave radiation ​(//​swrad//​) ​and albedo of the snow (//​albedo_snow//​). Additionally snow melt may be adjusted by the snow cover (//​effcover//​),​ see model 0
  
-<​m> ​melt = cmrad * swrad * (1.-albedo_snow) </m>+<​m> ​rpmelt ​= cmrad * swrad * (1.-albedo_snow) ​* effcover ​</m>
  
 The parameter //cmrad// is related to land use. Snow albedo is calculated as decreasing with the age of snow (//​snowage//​),​ and depend on land use specific parameters (//albmax, albmin// and //​albkexp//​). The parameter //cmrad// is related to land use. Snow albedo is calculated as decreasing with the age of snow (//​snowage//​),​ and depend on land use specific parameters (//albmax, albmin// and //​albkexp//​).
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 <m> albedo_snow = albmin+(albmax-albmin)*EXP(-albkexp*snowage) </m> <m> albedo_snow = albmin+(albmax-albmin)*EXP(-albkexp*snowage) </m>
  
-The two melting parts are added. Snow melt routine consider also that snow melt (and liquid content of snow) can refreeze for temperatures below the threshold (//ttmp//).+The two potential ​melting parts are added for this model. Snow melt routine consider also that snow melt (and liquid content of snow) can refreeze for temperatures below the threshold (//​ttmp//​). ​The refreezing resuces the snow melt. The refreezing occur when temperature is below the threshold (//ttmp//) and is a fraction of the (negative) potential temperature index "snow melt". The fraction is given by the general model parameter //​cmrefr//​. 
 + 
 +<m> refreeze = cmrefr*cmlt*(ttmp-temp) </​m>​ 
 + 
 +<m> melt = MIN(pmelt+rpmelt-refreeze,​snow) </​m>​ 
  
 === Snow heat === === Snow heat ===
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 The snow distribution factor (//​fscdist//​) is determined by three land use dependent parameters; //​fscdist0//​ and //​fscdist1//​ in the linear equation and a maximum value (//​fscdistmax//​). Also in this case the snowcover is limited by the maximum and minimum value parameters. When the end of the snow season approaches (defined by general parameter //fsck1//) the //snowmax// variable is gradually decreased in order to be reset before next winter season: The snow distribution factor (//​fscdist//​) is determined by three land use dependent parameters; //​fscdist0//​ and //​fscdist1//​ in the linear equation and a maximum value (//​fscdistmax//​). Also in this case the snowcover is limited by the maximum and minimum value parameters. When the end of the snow season approaches (defined by general parameter //fsck1//) the //snowmax// variable is gradually decreased in order to be reset before next winter season:
  
-<m> snowmax=snowmax-(fsck1*snowmax-snow)*{1-e^{-fsckexp*ts}}/​{fsck1} </m>+<m> snowmax=snowmax-(fsck1*snowmax-snow)*{(1-e^{-fsckexp*ts})}/{fsck1} </m>
  
 <m> {snow}/​{snowmax}<​fsck1 </m> <m> {snow}/​{snowmax}<​fsck1 </m>
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 The equation depends on two general parameters, //fsck1// and //​fsckexp//,​ where //fsckexp// depend on time (//ts// is seconds per timestep of simulation). The equation depends on two general parameters, //fsck1// and //​fsckexp//,​ where //fsckexp// depend on time (//ts// is seconds per timestep of simulation).
  
-For winters when the snow pack not reach the definition of large snow pack, the first equation is used during the whole season. ​+For winters when the snow pack does not reach the definition of large snow pack, the first equation is used during the whole season. For winters when the snow does not melt completely, the second equation is continued to be used.
  
 ==== Snow depth ==== ==== Snow depth ====
  
-In the default snow depth model, snow density (//​snowdens//​) depends on the snow's age in days (//​snowage//​). ​Snow density for fresh snow (//​sdnsnew//​) and the increase of density with snow age (//​snowdensdt//​) ​are general ​parameters ​(~ 0.1 and ~0.002). The snow's age increases by one every time step, but are weighted with age (0) for any new snow.+There are two alternative snow depth models implemented in HYPE. Both use the snow density of fresh snow. Snow density for fresh snow is set by a general parameter (//​sdnsnew//​ ~0.1). If there is wind and a wind scale parameter is given, then the fresh snow density (<​m>​sdnsnew_{scaled}</​m>​) is scaled with the wind factor (//​sdnswscale//​ and maximum snow density (//​sdnsmax//​).  
 + 
 +<​m> ​ sdnsnew_{scaled} = sdnsnew + (max(0.5,​sdnsmax)-sdnsnew)*(1 - exp({-wind*sdnswscale})) </​m>​ 
 + 
 +In the default snow depth model, snow density (//​snowdens//​) depends on the snow's age in days (//​snowage//​). ​The increase of density with snow age (//​snowdensdt//​) ​is a general ​parameter ​(~0.002 ​g/cm3/d). The snow's age increases by one every time step, but are weighted with age (0) for any new snow.
  
 <​m> ​ snowage = (snowage + 1)*oldsnow/​(oldsnow+snowfall) </m> <​m> ​ snowage = (snowage + 1)*oldsnow/​(oldsnow+snowfall) </m>
  
-<​m> ​ snowdens = sdnsnew ​+ snowdensdt * snowage </m>+<​m> ​ snowdens = sdnsnew_{scaled} ​+ snowdensdt * snowage/​timesteps_perday ​</m>
  
 <​m> ​ snowdepth = 0.1 * snow/​snowdens </m> <​m> ​ snowdepth = 0.1 * snow/​snowdens </m>
  
-In the alternative snow depth model, snow density is calculated by a compacting factor. ​Snow density for fresh snow (//​sdnsnew//​),​ maximum ​snow density (//​sdnsmax//​),​ compactation rate for low temperatures (//​sdnsrate//​) and additional compactation for high temperature (//​sdnsradd//​) are all general parameters. The change in snowdensity (//​densdt//​) due to compactation each time step is calculated as:+In the alternative snow depth model, snow density is calculated by a compacting factor. ​Maximum ​snow density (//​sdnsmax//​),​ compactation rate for low temperatures (//​sdnsrate//​) and additional compactation for high temperature (//​sdnsradd//​) are all general parameters ​used for this model. The change in snowdensity due to snowfall is calculated from the updated snow depth (snowfall added with density <​m>​sdnsnew_{scaled}</​m>​) and snow pack. The change in snowdensity (//​densdt//​) due to compactation each time step is calculated as:
  
 <​m> ​ densdt = sdnsrate*(sdnsmax-snowdens) </m> <​m> ​ densdt = sdnsrate*(sdnsmax-snowdens) </m>
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 ^Section ^Symbol ^Parameter/​Data ^File ^ ^Section ^Symbol ^Parameter/​Data ^File ^
 |Snow| |//​whcsnow//​|[[start:​hype_file_reference:​par.txt|par.txt]]| |Snow| |//​whcsnow//​|[[start:​hype_file_reference:​par.txt|par.txt]]|
-|Snow melt|//cmlt, ttmp, fcseff//|//cmlt, ttmp, fcseff//​|[[start:​hype_file_reference:​par.txt|par.txt]]|+|Snow melt|//​ttmp,​ fcseff//​|//​ttmp,​ fcseff//​|[[start:​hype_file_reference:​par.txt|par.txt]]
 +|:::​|//​cm//​|//​cmlt,​ cmltcorr//​|:::​|
 |:::​|//​albmin,​albmax,​albkexp,​cmrad//​|//​albmin,​albmax,​albkexp,​cmrad//​|:::​| |:::​|//​albmin,​albmax,​albkexp,​cmrad//​|//​albmin,​albmax,​albkexp,​cmrad//​|:::​|
 |:::| |//sdnsnew, snkika//​|:::​| |:::| |//sdnsnew, snkika//​|:::​|
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 |:::​|//​fscmax,​ fscdist0, fscdist1, fsck1, fsckexp//​|//​fscmax,​ fscdist0, fscdist1, fsck1, fsckexp//​|[[start:​hype_file_reference:​par.txt|par.txt]]| |:::​|//​fscmax,​ fscdist0, fscdist1, fsck1, fsckexp//​|//​fscmax,​ fscdist0, fscdist1, fsck1, fsckexp//​|[[start:​hype_file_reference:​par.txt|par.txt]]|
 |:::| |//​fscmin,​fsclim,​fscdistmax//​|:::​| |:::| |//​fscmin,​fsclim,​fscdistmax//​|:::​|
-|Snow depth| |//sdnsnew, snowdensdt, sdnsmax, sdnsrate, sdnsradd, ttmp//​|[[start:​hype_file_reference:​par.txt|par.txt]]|+|Snow depth| ​ |//sdnsnew, snowdensdt, sdnsmax, sdnsrate, sdnsradd, ttmp, sdnswscale//​|[[start:​hype_file_reference:​par.txt|par.txt]]| 
 +|:::​|//​wind//​|calculated from|[[start:​hype_file_reference:​uobs.txt|Uobs.txt]] or [[start:​hype_file_reference:​uwobs.txt|UWobs.txt]] and [[start:​hype_file_reference:​vwobs.txt|VWobs.txt]]|
  
  
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 <m> soiltemp=weight_{air}*T+(1-weight_{air}-weight_{deep} )*soiltemp+weight_{deep}*deeptemp </m> <m> soiltemp=weight_{air}*T+(1-weight_{air}-weight_{deep} )*soiltemp+weight_{deep}*deeptemp </m>
  
-Negative soil temperature will freeze part of the soil water and affect evaporation,​ percolation and runoff. ​This is a model option, and two variants ​can be selected for simulation.+Negative soil temperature will freeze part of the soil water and affect evaporation,​ percolation and runoff. ​It was used by Stadnyk et al (2020). The effect of frozen soil can be included in simulation by a model option. The model option come in two variants.
  
 A fraction of the soil water is assumed in liquid phase for each soil layer (//​liqfrac//​). It is assumed equal in the different “pores”,​ i.e the same fraction frozen in water below wilting point, in water in field capacity and in water available for runoff. The fraction of liquid water for a soil layer is calculated from the temperature of the soil layer (//​soiltemp//,​ degree Celsius), soil water (//​water//​),​ porosity (//pw//) and two soil type dependent parameters (//​par<​sub>​logsatm</​sub>,​ par<​sub>​bcosby</​sub>//​): ​ A fraction of the soil water is assumed in liquid phase for each soil layer (//​liqfrac//​). It is assumed equal in the different “pores”,​ i.e the same fraction frozen in water below wilting point, in water in field capacity and in water available for runoff. The fraction of liquid water for a soil layer is calculated from the temperature of the soil layer (//​soiltemp//,​ degree Celsius), soil water (//​water//​),​ porosity (//pw//) and two soil type dependent parameters (//​par<​sub>​logsatm</​sub>,​ par<​sub>​bcosby</​sub>//​): ​
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 <m> liqfrac=1 , soiltemp>​0 </m> <m> liqfrac=1 , soiltemp>​0 </m>
  
-<m> liqfrac={pw/​water}*{({-334000*soiltemp}/​{9.81*(soiltemp+273.16)*10^{par_logsatm/​100}})^{-1/​par_bcosby}} , soiltemp<​0 </m>+<m> liqfrac={pw/​water}*{({-334000*soiltemp}/​{9.81*(soiltemp+273.16)*10^{par_logsatm}*{1/​100}})^{-1/​par_bcosby}} , soiltemp<​0 </m>
  
 An alternative model for calculation of liquid fraction is available. In the alternate model each soillayer is divided into three equal thick temporary layers and a soil temperature for each of these are determined. Then the fraction of liquid phase is calculated for the temporary layers based on their soil temperatures. The average of the liqfrac for the temporary layers is then applied to the soil layer in the following calculations. An alternative model for calculation of liquid fraction is available. In the alternate model each soillayer is divided into three equal thick temporary layers and a soil temperature for each of these are determined. Then the fraction of liquid phase is calculated for the temporary layers based on their soil temperatures. The average of the liqfrac for the temporary layers is then applied to the soil layer in the following calculations.
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 The expansion of ice decreases pore volume for liquid water. In HYPE this is assumed to affect soil layer runoff by increasing the pressure level in the soil layers. Since the ice is assumed equally divided between pores, this can actually force water to fill ep-pores and have some water available for runoff even though //​water<​wp+fc//​. Expansion is set with a general parameter, //​fzsexpand//,​ and could be up to 10% (i.e. parameter value 0.1). The expansion of ice decreases pore volume for liquid water. In HYPE this is assumed to affect soil layer runoff by increasing the pressure level in the soil layers. Since the ice is assumed equally divided between pores, this can actually force water to fill ep-pores and have some water available for runoff even though //​water<​wp+fc//​. Expansion is set with a general parameter, //​fzsexpand//,​ and could be up to 10% (i.e. parameter value 0.1).
 +
 +==== Evapotranspiration ==
 +
 +Evaporation from soil is assumed to occur from the two upper layers. The potential evaporation is assumed to decrease exponentially with depth (depending on the parameter //​epotdist//​). The potential evaporation is divided between the two layers (//​epotfrac//​) with the distribution depending on the potential evaporation in the midpoint of each soil layer (figure 6). This is then used by approximating to a rectangle. Since soil layers differ between classes, the evaporation distribution do to.
 +
 +<m> epot1 = EXP(- epotdist*soillayerdepth(1){/​}2) </m>
 +
 +<m> epot2 = EXP(- epotdist*(soillayerdepth(1)+{soillayerdepth(2)-
 +          soillayerdepth(1)}/​2)) </m>
 +          ​
 +<​m> ​ area1 = soillayerdepth(1)*epot1 </m>
 +
 +<​m> ​ area2 = (soillayerdepth(2)-soillayerdepth(1))*epot2 </m>
 +
 +<m> epotfrac1 = area1 / {area1 + area2} </m>
 +
 +<​m> ​ epotfrac2 = area2 / {area1 + area2} </m>
 +
 +
 +
 +|{{:​start:​hype_model_description:​potentialevaporation.png?​400|}}|
 +|Figure 6 The distribution of potential evaporation between the top two soil layers.|
 +
 +
 +The actual evaporation from a soil layer (//evap//) is limited by the availability of water in the soil (//soil//) above the wilting point (//wp//, mm). Evaporation is at potential rate only if the water exceeds field capacity (//fc//, mm) or a (large) proportion (general parameter //lp//) of field capacity. In between these limits evaporation increase linearly.
 +
 +<m> evapp= {lbrace}{
 + ​\matrix{3}{2}
 +    {0 {soil-wp<​0}
 +    epot*epotfrac {soil-wp>​lp*fc}
 +    epot*epotfrac*{{soil-wp}/​{lp*fc}} {else} }} </m>
 +
 +<m> evap = MAX(evapp,​soil-wp) </m>
 +
 +
 +|{{:​start:​hype_model_description:​evap.png?​400|}}|
 +|Figure 7 Evaporation as a function of soil water.|
 +
 +The actual evaporation may also depend on soil temperature (//​soiltemp//​). It is then reduced for temperatures above land use parameter //ttrig// and depend on two other land use parameters (//tredA//, //tredB//) as well (Figure 3). 
 +
 +| {{:​start:​hype_model_description:​pet_soiltemp.png?​400}} ​                                                                                   |
 +| Figure 8 Soil temperature factor for reduction of soil evapotranspiration. \\ Parameter values: //​ttrip//​=1,​ //​tredA//​=0.5,​ //​tredB//​=1. ​ |
 +
 +The soil temperature evapotranspiration reduction is calculated as:
 +
 +<m> factor = 1-e^( - tredA*(soiltemp-ttrig)^tredB) </m>
 +
 +<m> evapp = evapp*factor </m>
 +
 +The actual soil evaporation is set to zero for temperatures below the threshold temperature and for negative potential evaporation estimates (condensation). It may also be affected by frozen soil model, which then limit evaporation to the liquid part of soil water.
 +
 +
  
 ==== Groundwater runoff ==== ==== Groundwater runoff ====
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            ​({soillayerdepth(k)} - streamdepth) </m>            ​({soillayerdepth(k)} - streamdepth) </m>
   ​   ​
 +If the frozen soil model is used, it influences in two ways; one, the water available for runoff is reduced to the liquid fraction, and two, the frozen water is assumed to expand possibly increasing the water level in the soil.
 +
 |{{:​start:​hype_model_description:​runofffromthird_layer.png?​400|}}| |{{:​start:​hype_model_description:​runofffromthird_layer.png?​400|}}|
-|Figure ​6: Runoff from the third soil layer with a stream.|+|Figure ​9: Runoff from the third soil layer with a stream.|
  
 Soil layers that lye entirely below the stream depth have no groundwater runoff. Soil layers that lye entirely below the stream depth have no groundwater runoff.
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 ==== Runoff through drainage pipes ==== ==== Runoff through drainage pipes ====
  
-Runoff in the drainage pipes occurs when the water table (the percentage of filled pores of the effective porosity) rises above the pipe's depth (figure ​7). Runoff depends on the groundwater surface elevation over the pipe (//​deltah//,​ m), and a recession coefficient //trrcs//. Recession parameter //trrcs// depends on soil type, while drainage pipe level depends on the class. The recession parameter is adjusted with the correction parameter //​rrcscorr//​ for different parameter regions (//​parreg//​). It is defined as an increase.+Runoff in the drainage pipes occurs when the water table (the percentage of filled pores of the effective porosity) rises above the pipe's depth (figure ​10). Runoff depends on the groundwater surface elevation over the pipe (//​deltah//,​ m), and a recession coefficient //trrcs//. Recession parameter //trrcs// depends on soil type, while drainage pipe level depends on the class. The recession parameter is adjusted with the correction parameter //​rrcscorr//​ for different parameter regions (//​parreg//​). It is defined as an increase.
  
 <m> trrcs = trrcs*(1+rrcscorr) </m> <m> trrcs = trrcs*(1+rrcscorr) </m>
 +
 +In addition the tile drainage can be adjusted if not the whole class is assumed to be drained by ditches. The fraction of drain area for the class is allowed to affect the recession parameter to reduce the effect of tile drainage.
 +
 +<m> trrcs=trrcs*tilefrac </m>
 +
 +where tilefrac is given per subbasin and class, or a group of classes called ''​tilegroup''​.
  
 Depending on which soil layer drainage pipe is in, the runoff will be calculated for water in that soil layer. For the soil layer //k// (//​soil(k)//​ is the water content in soil layer //k//) runoff is calculated as the parameter //trrcs// times the water found in the effective porosity of the layer and of the overlying soil layers if it is full.  Depending on which soil layer drainage pipe is in, the runoff will be calculated for water in that soil layer. For the soil layer //k// (//​soil(k)//​ is the water content in soil layer //k//) runoff is calculated as the parameter //trrcs// times the water found in the effective porosity of the layer and of the overlying soil layers if it is full. 
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     runoffd = trrcs * deltah / soillayerthick(k) * ep(k)     runoffd = trrcs * deltah / soillayerthick(k) * ep(k)
     ​     ​
 +If the frozen soil model is used, it influences in two ways; one, the water available for runoff is reduced to the liquid fraction, and two, the frozen water is assumed to expand possibly increasing the water level in the soil. 
  
 |{{:​start:​hype_model_description:​runoffthorughdrainagepipes.png?​400|}}| |{{:​start:​hype_model_description:​runoffthorughdrainagepipes.png?​400|}}|
-|Figure ​7: Illustration for calculation of runoff through the drainage pipes.|+|Figure ​10: Illustration for calculation of runoff through the drainage pipes.|
  
-==== Infiltration ====+==== Infiltration ​and surface runoff ​====
 Infiltration is calculated from the sum of rain and snowmelt (//​infilt0//,​ mm/time step) . Infiltration is calculated from the sum of rain and snowmelt (//​infilt0//,​ mm/time step) .
  
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-Surface runoff due to excess infiltration and macropore flow are calculated from the sum of snow melt and rainfall; the water available for infiltration (//​infilt0//​).+There are alternative models for diversion ​of flow from water available for infiltration (//​infilt0//​) ​to be chosen from. All model options result in a division of available water into three flow paths; surface runoff to the nearest stream, infiltration to top soil layer, and macropore flow to the soil layer where the groundwater table is currently located.
  
-If the current infiltration rate is greater than a threshold (//​mactrinf//,​ mm/​timestep) then macropore flow (//​macroflow//​) and surface runoff (//​infoverflow//​) may occur. In addition, the water in the upper soil layer needs to be larger than another threshold (//​mactrsm//​) for surface ​runoff ​and macropore flow to occur. The two flows are calculated as a percentage (//​macrate//​ respective //srrate//) of the infiltration above the first threshold;+The original and default model is based on runoff coefficients and thresholds for infiltration and soil moisture. Surface runoff due to excess infiltration and macropore flow are calculated from the sum of snow melt and rainfall; the water available for infiltration (//​infilt0//​). 
 + 
 +If the current infiltration rate is greater than a threshold (//​mactrinf//,​ mm/​timestep) then macropore flow (//​macroflow//​) and surface runoff (//​infoverflow//​) may occur. In addition, the water in the upper soil layer needs to be larger than another threshold. This threshold is determined by a soil type dependent parameter ​(//​mactrsm//​) ​multiplied by the water not available ​for runoff ​(i.e. //​fc//​+//​wp//​). The two flows are calculated as a percentage (//​macrate//​ respective //srrate//) of the infiltration above the first threshold;
  
 <m> macroflow = macrate * (infilt0 - mactrinf) </m> <m> macroflow = macrate * (infilt0 - mactrinf) </m>
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 <m> infilt = infilt0 - macroflow - infoverflow </m> <m> infilt = infilt0 - macroflow - infoverflow </m>
 +
 +An alternative flow diversion model calculates surface runoff and macroporeflow from a surface runoff coefficient based on current (//S//) and maximum soil moisture (//Smax//). The soil moisture can be based on one, two or all three soil layers.
 +<m> S=SUM(soil(j)) j=1,nlayer </m>
 +<m> Smax=SUM(pw(j) J=1,nlayer </m>
 +where  //soil(j)// is soil water of soil layer //j// (mm), //pw(j)// is pore volume of soil layer //j// (mm) and calculated from the model parameters for water holding capacity (//wcwp//, //wcfc// and //wcep//), //nlayer// is set by a general model parameter (//​srnlayer//​).
 +The surface runoff coefficient (//​srratio//​) is a "​beta-function",​ with the general parameter //srbeta// as exponent //beta//
 +<m> srratio = (S/​Smax)^beta </m>,
 +but limited to one. A fraction of the diverted flow goes to macropore flow (//​macroflow//​),​ while the rest become surface runoff (//​infoverflow//​). The infiltration (//​infilt//​) is the rest of the available water.
 +<m> macroflow = macfrac*srratio*infilt0 </m>
 +<m> infoverflow = (1-macfrac)*srratio*infilt0 </m>
 +<m> infilt = (1. - srratio)*infilt0 </m>
 +
 +Another alternative flow diversion model calculates surface runoff and macroporeflow from a surface runoff coefficient based on current (//S//) and maximum soil moisture (//Smax//) and from current available water for infiltration. This model is similar to the one above but the exponent of the surface runoff coefficient (//beta//) is calculated from two general parameters and //​infilt0//​.
 +<m> beta = sralpha / infilt0^srgamma </m>
 +
  
 === Additional infiltration limitation by frozen soil === === Additional infiltration limitation by frozen soil ===
  
-An optional model for infiltration limitation and diversion of flow considers the effect of frozen soil. It is developed based on Zhao and Gray (1999). This model redirects all or part of the remaining infiltration,​ after calculating the diversion of surface runoff and macropore flow as described above. Note that this is not part of the frozen soil model option described above ([[:​start:​hype_model_description:​hype_land#​soil_temperature_and_frozen_soil|Soil temperature and frozen soil]]).+An optional model for infiltration limitation and diversion of flow considers the effect of frozen soil. It is developed based on Zhao and Gray (1999) and tried by Stadnyk et al (2020). This model redirects all or part of the remaining infiltration,​ after calculating the diversion of surface runoff and macropore flow as described above. Note that this is not part of the frozen soil model option described above ([[:​start:​hype_model_description:​hype_land#​soil_temperature_and_frozen_soil|Soil temperature and frozen soil]]).
  
 If the minimum daily temperature is less than 10 degrees and the infiltration is larger than 5mm/d an ice lens is created in the soil. In this case, and as long as the maximum daily temperature is below zero, the ice lens redirect all infiltration to surface runoff and macropore flow. If the minimum daily temperature is less than 10 degrees and the infiltration is larger than 5mm/d an ice lens is created in the soil. In this case, and as long as the maximum daily temperature is below zero, the ice lens redirect all infiltration to surface runoff and macropore flow.
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 ==== Percolation ==== ==== Percolation ====
  
-The flow of water downward through the soil layers is only done by water over field capacity (water in the effective porosity). A maximum percolation (mm/d) limits the flow between soil layers. For the upper soil layer it is //mperc1//, and for the second soil layer it is //mperc2//. These parameters are soil type dependent. Flow is also limited by how much water the lower layer can receive.+The flow of water downward through the soil layers is only possible for water over field capacity (water in the effective porosity ​part of the pore volume). For a frozen soil, percolation is only acting on the liquid water of the soil. A maximum percolation (mm/d) limits the flow between soil layers. For the upper soil layer it is //mperc1//, and for the second soil layer it is //mperc2//. These parameters are soil type dependent. Flow is also limited by how much water the lower layer can receive.
  
 Drainage from soil layer 1 to soil layer 2 is Drainage from soil layer 1 to soil layer 2 is
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 |:::| |//​parreg//​|:::​| |:::| |//​parreg//​|:::​|
 |Runoff through drainage pipes| |//​trrcs//​|[[start:​hype_file_reference:​par.txt|par.txt]]| |Runoff through drainage pipes| |//​trrcs//​|[[start:​hype_file_reference:​par.txt|par.txt]]|
-|Infiltration| |//​mactrinf,​ mactrsm, macrate, srrate, bfroznsoil//​|[[start:​hype_file_reference:​par.txt|par.txt]]|+|:::| |//​tilegroup//​|[[start:​hype_file_reference:​classdata.txt|ClassData.txt]]| 
 +|:::​|//​tilefrac//​|//​tilefrac_1,​ tilefrac_2,​...,​tilefrac_10//​|[[start:​hype_file_reference:​geodata.txt|GeoData.txt]]| 
 +|Infiltration| |//​mactrinf,​ mactrsm, macrate, srrate, bfroznsoil, macfrac//​|[[start:​hype_file_reference:​par.txt|par.txt]]|
 |:::​|//​pw//​|calculated from //​wc+fc+wp//​|:::​| |:::​|//​pw//​|calculated from //​wc+fc+wp//​|:::​|
 +|:::​|//​beta//​|//​srbeta//​ or calculated from //sralpha, srgamma//​|:::​|
 +|:::​|//​nlayer//​|//​srnlayer//​|:::​|
 |Percolation| |//mperc1, mperc2//​|[[start:​hype_file_reference:​par.txt|par.txt]]| |Percolation| |//mperc1, mperc2//​|[[start:​hype_file_reference:​par.txt|par.txt]]|
 |Saturated surface runoff| |//​srrcs//​|[[start:​hype_file_reference:​par.txt|par.txt]]| |Saturated surface runoff| |//​srrcs//​|[[start:​hype_file_reference:​par.txt|par.txt]]|
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 | [[http://​hype.sourceforge.net/​doxy-html/​namespacesoil__processes.html|soil_processes (soil_proc.f90)]] | calculate_soiltemp | soil temperature and frozen soil | | [[http://​hype.sourceforge.net/​doxy-html/​namespacesoil__processes.html|soil_processes (soil_proc.f90)]] | calculate_soiltemp | soil temperature and frozen soil |
 | ::: | calculate_weigthed_temperature | ::: | | ::: | calculate_weigthed_temperature | ::: |
 +| ::: | calculate_unfrozen_soil_water| ::: |
 +| ::: | calculate_three_soil_temperature| ::: |
 +| ::: | calculate_liquid_water_fraction| ::: |
 | ::: | initiate_soil_water | groundwater runoff | | ::: | initiate_soil_water | groundwater runoff |
 | ::: |calculate_soil_runoff| ::: | | ::: |calculate_soil_runoff| ::: |
 | ::: |calculate_tile_drainage| runoff thorugh drainage pipes | | ::: |calculate_tile_drainage| runoff thorugh drainage pipes |
-| ::: |infiltration ​| diversion of surface runoff and macropore flow, infiltration |+| ::: |calculate_infiltration_flow_diversion ​| diversion of surface runoff and macropore flow, infiltration ​
 +| ::: |add_infiltration | ::: |
 | ::: |percolation | percolation | | ::: |percolation | percolation |
 | ::: |add_macropore_flow | macropore flow | | ::: |add_macropore_flow | macropore flow |
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 Glacier melting, snow melting on snowfield and/or rain are added to the soil. Thus the soil represents the whole glacier class area. The concentrations in the glacial melt water are zero. This means that any atmospheric deposition of nutrients is lost on the glacier. Glacier melting, snow melting on snowfield and/or rain are added to the soil. Thus the soil represents the whole glacier class area. The concentrations in the glacial melt water are zero. This means that any atmospheric deposition of nutrients is lost on the glacier.
  
 +The soil water is calculated as described above.
 ==== Links to file reference ==== ==== Links to file reference ====
  
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 |//T//|see needed data in [[start:​hype_model_description:​processes_above_ground#​links_to_file_reference|Links for temperature]]| | |//T//|see needed data in [[start:​hype_model_description:​processes_above_ground#​links_to_file_reference|Links for temperature]]| |
 |//​swrad//​|calculated or from|[[start:​hype_file_reference:​swobs.txt|SWobs.txt]]| |//​swrad//​|calculated or from|[[start:​hype_file_reference:​swobs.txt|SWobs.txt]]|
-|//coef0//​|//​glacvcoef//​ or //​glacvcoef1//​|[[start:​hype_file_reference:​par.txt|par.txt]]|+|//coef//​|//​glacvcoef//​ or //​glacvcoef1//​|[[start:​hype_file_reference:​par.txt|par.txt]]|
 |//​exp//​|//​glacvexp//​ or //​glacvexp1//​|:::​| |//​exp//​|//​glacvexp//​ or //​glacvexp1//​|:::​|
 |//cmlt, ttmp//​|//​glaccmlt,​ glacttmp//​|:::​| |//cmlt, ttmp//​|//​glaccmlt,​ glacttmp//​|:::​|
 |//​albedo<​sub>​snow</​sub>//​|calculated from //snalbmin, snalbmax, snalbkexp//​|:::​| |//​albedo<​sub>​snow</​sub>//​|calculated from //snalbmin, snalbmax, snalbkexp//​|:::​|
-| |//glacalb, glacdens, glac2arlim, crefr, cmrad, ​fepotglac//|:::|+| |//glacalb, glacdens, glac2arlim,fepotglac//​|:::​| 
 +|//crefr, cmrad//​|//​glaccrefrglaccmrad//|:::|
  
 ==== Links to relevant procedures in the code ==== ==== Links to relevant procedures in the code ====
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 Lindström, G., K. Bishop, and M. Ottosson Löfvenius, 2002. Soil frost and runoff at Svartberget,​ northern Sweden - measurements and model analysis, Hydrological Processes, 16:​3379-3392. Lindström, G., K. Bishop, and M. Ottosson Löfvenius, 2002. Soil frost and runoff at Svartberget,​ northern Sweden - measurements and model analysis, Hydrological Processes, 16:​3379-3392.
 +
 +Radic, V. and Hock, R., 2010. Regional and global volumes of glaciers derived from statistical upscaling of glacier inventory data, J. Geophys. Res., 115, F01010, doi:​10.1029/​2009JF001373.
  
 Samuelsson, P., S. Gollvik, and A. Ullerstig, 2006. The land-surface scheme of the Rossby Centre regional atmospheric climate model (RCA3), SMHI Report Meteorologi Nr 122, 25 pp.  Samuelsson, P., S. Gollvik, and A. Ullerstig, 2006. The land-surface scheme of the Rossby Centre regional atmospheric climate model (RCA3), SMHI Report Meteorologi Nr 122, 25 pp. 
  
-RadicV. and HockR.2010. Regional ​and global volumes of glaciers derived from statisti-cal upscaling of glacier inventory data, JGeophysRes., 115, F01010, ​doi:10.1029/2009JF001373.+StadnykTAMK MacDonald, A Tefs, SJ Déry, K Koenig, D Gustafsson, K Isberg, and B Arheimer2020Hydrological modeling of freshwater discharge into Hudson Bay using HYPEElem Sci Anth8: 43. doi:10.1525/elementa.439
  
 Zhao, L., and D.M. Gray 1999. Estimating snowmelt infiltration into frozen soils, Hydrological Processes, 13:​1827-1842. Zhao, L., and D.M. Gray 1999. Estimating snowmelt infiltration into frozen soils, Hydrological Processes, 13:​1827-1842.
start/hype_model_description/hype_land.1588148105.txt.gz · Last modified: 2023/11/16 14:28 (external edit)