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start:hype_model_description:hype_np_soil [2018/12/14 13:12]
cpers [Soil erosion]
start:hype_model_description:hype_np_soil [2019/05/09 08:28] (current)
cpers [Crop cover and ground cover]
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   ​   ​
 for the growing period. Outside the growing period the uptake is assumed to be zero. for the growing period. Outside the growing period the uptake is assumed to be zero.
 +
 +
 +|{{:​start:​hype_model_description:​uptake.png?​400|}}|
 +|Figure 2 Uptake function over a year with growing period bd2=100 to bd3=230. Effect of changing parameters up1-up3.|
 +
            
-Autumn-sown crops may take up IN and SP for a while after sowing in autumn. The same potential uptake of nitrogen as the main growing season are used, but uptake is limited by a temperature function. This uptake will run from the autumn sowing date (//bd5//) to the mid winter (end of the year in northern hemisphere). +Autumn-sown crops may take up IN and SP for a while after sowing in autumn. The same potential uptake of nitrogen as the main growing season are used, but uptake is limited by a temperature function. This uptake will run from the autumn sowing date (//bd5//) to the mid winter (31 December or 30 June depending on the autumn sawing date). 
  
 <m> help = (up1-up2)*e^{-up3*(dayno-(bd5+25))} </m> <m> help = (up1-up2)*e^{-up3*(dayno-(bd5+25))} </m>
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 <m> GDD(d+1)=GDD(d)+MAX(0,​T-basetemp) </m> <m> GDD(d+1)=GDD(d)+MAX(0,​T-basetemp) </m>
  
-where //d// is day of year, //T// is air temperature (degree Celcius), //​basetemp//​ is a temperature threshold. The GDD is accumulated for each day after //​firstday//​ with day length larger than //​daylength//​. The GDD is zeroed at mid winter (new year in northern hemisphere).+where //d// is day of year, //T// is air temperature (degree Celcius), //​basetemp//​ is a temperature threshold. The GDD is accumulated for each day after //​firstday//​ with day length larger than //​daylength//​. The GDD is zeroed at //​firstday//​.
  
 ==== Soil erosion ==== ==== Soil erosion ====
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 Eroded sediment (kg/km2) is calculated as: Eroded sediment (kg/km2) is calculated as:
  
-<m> erodedSed = 1000 * (MobilisedRain + MobilisedSedSR) * transportfactor </m>+<m> erodedSed = 1000 * (MobilisedRain + MobilisedSR) * transportfactor </m>
   ​   ​
 The alternative erosion model calculates eroded sediment (//​erodedSed//​ (kg/km2)) based on precipitation (//prec//) and a number of model parameters and subbasin input data. The alternative erosion model calculates eroded sediment (//​erodedSed//​ (kg/km2)) based on precipitation (//prec//) and a number of model parameters and subbasin input data.
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 The parameters //​erodslope//,​ //erodexp// and //​erodindex//​ are general. The parameters //​erodluse//​ and //​erodsoil//​ are land-use and soil type dependent. Subbasin input is needed on //slope//, the subbasins average slope, and an erosion index, //EI//. The parameters //​erodslope//,​ //erodexp// and //​erodindex//​ are general. The parameters //​erodluse//​ and //​erodsoil//​ are land-use and soil type dependent. Subbasin input is needed on //slope//, the subbasins average slope, and an erosion index, //EI//.
  
-A selective process is affecting the soil erosion of phosphorus. Smaller and lighter particles are eroded easier than larger ones. The tiny particles contain more P per unit weight than the average particle of the soil. Therefore an enrichment factor (//​enrichment//​) is used. The enrichment factor is calculated from three parameters (//​ppenrmax,​ ppenrstab, ppenrflow//​),​ one of which is soil type dependent (//​ppenrmax//​),​ and the particle bearing flow. Typical values of the parameters, here called max, stab and flowstab, are given in the example in Figure ​2.+A selective process is affecting the soil erosion of phosphorus. Smaller and lighter particles are eroded easier than larger ones. The tiny particles contain more P per unit weight than the average particle of the soil. Therefore an enrichment factor (//​enrichment//​) is used. The enrichment factor is calculated from three parameters (//​ppenrmax,​ ppenrstab, ppenrflow//​),​ one of which is soil type dependent (//​ppenrmax//​),​ and the particle bearing flow. Typical values of the parameters, here called max, stab and flowstab, are given in the example in Figure ​3.
  
  
 |{{:​start:​hype_model_description:​enrich.png?​400|}}| |{{:​start:​hype_model_description:​enrich.png?​400|}}|
-|Figure ​The enrichment factor for particulate phosphorus during soil erosion.|+|Figure ​The enrichment factor for particulate phosphorus during soil erosion.|
  
  
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 ==== Crop cover and ground cover ==== ==== Crop cover and ground cover ====
  
-Crop cover and ground cover fractions (//​cropcover//​ and //​groundcover//​) are used in erosion ​equations ​for PP and the default sediment transport model. Harvested crops have seasonally varying ground and crop cover, while permanent vegetation (e.g. forest) has constant values for these parameters. The parameters ​(//ccmax1, ccmax2, gcmax1, gcmax2//​) ​needed for calculations ​are found in [[start:​hype_file_reference:​cropdata.txt|CropData.txt]]. Parameters //ccmax1// and //gcmax1// describe the maximum crop and ground cover during spring-summer growing season, parameters //ccmax2// and //gcmax2// are corresponding maxima for fall-winter. These maximum ratios are reached at //maxday1// and //​maxday2//,​ which are defined as halfway between planting and harvest, and halfway between autumn planting and midwinter, respectively ​(new year on northern hemisphere). After these dates coverage is maintained to the next ploughing, harvest, or until the growing season starts again in the spring (for winter crops) (Figure ​3). At the date of ploughing, ground and crop cover are set to zero. Parameters //bd1// and //bd4// describe the dates of spring ​respective ​autumn ploughing. ​If //bd4// is set to 365 it is assumed that the ground is covered (i.e. no autumn ploughing) until spring ​ploughing. During the period between harvesting and ploughing, crop cover is equal to ground cover (//​gcmax1//​). From sowing (or growth seasonbeginning in the spring) the coverage rates increase linearly up to their maximum values.+Erosion can be mitigated by protective vegetation or vegetation residues that are in contact with the ground. ​Crop cover and ground cover reduce ​erosion ​by rain and surface runoff ​for particulate phosphorus (PPand the default sediment transport model (SS). Each crop covers a fraction of the ground, thus for simultanous crops (1st and 2nd crop) their respective crop/ground cover is combined to a common crop/ground cover 
 + 
 +Harvested crops have seasonally varying ground and crop cover, while permanent vegetation (e.g. forest) has constant values for these parameters. The input data needed for calculations ​(//ccmax1, ccmax2, gcmax1, gcmax2//) are given in [[start:​hype_file_reference:​cropdata.txt|CropData.txt]]. Parameters //ccmax1// and //gcmax1// describe the maximum crop and ground cover during spring-summer growing season, parameters //ccmax2// and //gcmax2// are corresponding maxima for winter ​crop's growth. These maximum ratios are reached at //maxday1// and //​maxday2//,​ which are defined as halfway between planting and harvest, and halfway between autumn planting and midwinter (1 January or 30 June depending ​on autumn planting date), respectively. ​ From sowing the coverage fractions increase linearly up to their maximum values. After these dates maximum ​coverage is maintained to the next ploughing, harvest, or until the growing season starts again in the spring (for winter crops) (Figure ​4). During ​the period between harvesting and ploughing, crop cover is equal to ground cover (//​gcmax1//​). At ploughing, ground and crop cover are reduced ​to zero. Parameters //bd1// and //bd4// describe the dates of spring ​and autumn ploughing. ​In the case of spring ​sowingwhen no winter ​crop is crowingeither one of the ploughing parameters can be set for ploughing date. 
 {{ :​start:​hype_model_description:​groundcover_cropcover.png?​400 |}} {{ :​start:​hype_model_description:​groundcover_cropcover.png?​400 |}}
-|Figure ​3: Crop cover and ground cover development for four different crop configurations.|+|Figure ​4: Crop cover and ground cover development for four different crop configurations.|
  
 ==== Transformation of nitrogen from atmospheric deposition ==== ==== Transformation of nitrogen from atmospheric deposition ====
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 ==== Common functions ==== ==== Common functions ====
  
-Many soil processes depend on temperature and soil moisture. The following equations are used in these cases. The temperature function (figure ​3) depends on the estimated soil layer temperature (//​soiltemp//​). The soil temperature requires some parameters to be simulated, see Section [[start:​hype_model_description:​hype_land#​soil_temperature_and_snow_depth|Soil temperature and snow depth]].+Many soil processes depend on temperature and soil moisture. The following equations are used in these cases. The temperature function (figure ​5) depends on the estimated soil layer temperature (//​soiltemp//​). The soil temperature requires some parameters to be simulated, see Section [[start:​hype_model_description:​hype_land#​soil_temperature_and_snow_depth|Soil temperature and snow depth]].
  
   tmpfcn = 2**((soiltemp - 20.0) / 10.0)   tmpfcn = 2**((soiltemp - 20.0) / 10.0)
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   IF(temp < 0.0) tmpfcn = 0.0   IF(temp < 0.0) tmpfcn = 0.0
  
-The humidity function (figure ​4) depends on soil moisture (//soil//) in the soil layer and the parameters of wilting limit (//wp//), field capacity (//fc//) and effective porosity (//ep//) transformed to unit //mm//. All these humidities are specified as percentages. The function includes coefficients //​thetaupp//​ = 0.12, //​thetalow//​ = 0.08, //​thetapow//​ = 1.0 and //satact// = 0.6. Note that another function is used in the calculation of denitrification. For soil layers //k// = 1..3 the equation is:+The humidity function (figure ​6) depends on soil moisture (//soil//) in the soil layer and the parameters of wilting limit (//wp//), field capacity (//fc//) and effective porosity (//ep//) transformed to unit //mm//. All these humidities are specified as percentages. The function includes coefficients //​thetaupp//​ = 0.12, //​thetalow//​ = 0.08, //​thetapow//​ = 1.0 and //satact// = 0.6. Note that another function is used in the calculation of denitrification. For soil layers //k// = 1..3 the equation is:
  
   IF(soil >= wp + fc + ep) THEN   IF(soil >= wp + fc + ep) THEN
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   ENDIF   ENDIF
  
-The humidity function (figure ​4) is always less than or equal to one while the temperature function may be greater than one when the temperature exceeds 20 degrees.+The humidity function (figure ​6) is always less than or equal to one while the temperature function may be greater than one when the temperature exceeds 20 degrees.
  
 |{{:​start:​hype_model_description:​commonfunctionstemperature.png?​300}}| |{{:​start:​hype_model_description:​commonfunctionstemperature.png?​300}}|
-|Figure ​3: Common temperature function for soil processes|  ​+|Figure ​5: Common temperature function for soil processes|  ​
  
 |{{:​start:​hype_model_description:​commonfunctionshumidity.png?​300}}| |{{:​start:​hype_model_description:​commonfunctionshumidity.png?​300}}|
-|Figure ​4: Common humidity function for soil processes| ​  +|Figure ​6: Common humidity function for soil processes| ​  
  
 ==== Vegetation nutrient uptake ==== ==== Vegetation nutrient uptake ====
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 <m> denitr(k) = drate * INpool(k) * tmpfcn(k) * smfcn(k) * concfcn(k) ​ </m> <m> denitr(k) = drate * INpool(k) * tmpfcn(k) * smfcn(k) * concfcn(k) ​ </m>
  
-The coefficient //drate// is determined by land use dependent model parameters //​denitrlu//​ and //​denitrlu3//​. The temperature dependence (//​tmpfcn//​) is described above. The soil moisture function (figure ​5) is exponential and thus different from the general soil moisture function.+The coefficient //drate// is determined by land use dependent model parameters //​denitrlu//​ and //​denitrlu3//​. The temperature dependence (//​tmpfcn//​) is described above. The soil moisture function (figure ​7) is exponential and thus different from the general soil moisture function.
  
 <m> smfcn= delim{lbrace} <m> smfcn= delim{lbrace}
  ​{matrix{2}{2}{  ​{matrix{2}{2}{
    0 {soil<​pw*lim }    0 {soil<​pw*lim }
-   ​({soil}/​{pw}-{{dlim}/​{(1-dlim)}})^{exp} else+   ({{{soil}/​{pw}-{dlim}}/​{(1-dlim)}})^{exp} else
    }}{} </m>    }}{} </m>
  
 where  <​m>​pw=wp+fc+ep</​m>​ where  <​m>​pw=wp+fc+ep</​m>​
  
-The function depends on soil moisture (//soil//) and pore volume (//pw//). Is also depends on two constants; the limit where moisture is high enough to allow denitrification to occur (//dlim//= 0.7) and the exponent (//exp//= 2.5). These cannot currently be changed. The dependence of the denitrification rate on the IN concentration is described by a function with a half-saturation concentration (general parameter //hsatINs// was in earlier HYPE versions a constant equal to 1 mg/L) (Figure ​6).+The function depends on soil moisture (//soil//) and pore volume (//pw//). Is also depends on two constants; the limit where moisture is high enough to allow denitrification to occur (//dlim//= 0.7) and the exponent (//exp//= 2.5). These cannot currently be changed. The dependence of the denitrification rate on the IN concentration is described by a function with a half-saturation concentration (general parameter //hsatINs// was in earlier HYPE versions a constant equal to 1 mg/L) (Figure ​8).
  
 <m> concfcn = conc / {conc + hsatINs} </m> <m> concfcn = conc / {conc + hsatINs} </m>
  
 |{{:​start:​hype_model_description:​functionsdenitrhumidity.png?​300|Adds an ImageCaption tag}}| |{{:​start:​hype_model_description:​functionsdenitrhumidity.png?​300|Adds an ImageCaption tag}}|
-|Figure ​5: Soil moisture function in the denitrification process.|+|Figure ​7: Soil moisture function in the denitrification process.|
  
 |{{:​start:​hype_model_description:​functionsdenitrconcentration.png?​300|}}| |{{:​start:​hype_model_description:​functionsdenitrconcentration.png?​300|}}|
-|Figure ​6: Concentration function in the denitrification process.|+|Figure ​8: Concentration function in the denitrification process.|
  
 ==== Immobile soil nutrient pool transformations ==== ==== Immobile soil nutrient pool transformations ====
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 |soil layer three|modified soil layer three| |soil layer three|modified soil layer three|
 |{{:​start:​hype_model_description:​soilload2.png?​200|}}|{{:​start:​hype_model_description:​soilload3.png?​200|}}| |{{:​start:​hype_model_description:​soilload2.png?​200|}}|{{:​start:​hype_model_description:​soilload3.png?​200|}}|
-|Figure ​7: Components of calculated gross (brown) and net (green) loads of soil.||+|Figure ​9: Components of calculated gross (brown) and net (green) loads of soil.||
  
  
start/hype_model_description/hype_np_soil.1544789554.txt.gz · Last modified: 2018/12/14 13:12 by cpers