start:hype_model_description:hype_np_soil

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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> |

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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 2 The enrichment factor for particulate phosphorus during soil erosion.| | + | |Figure 3 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 season, beginning 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 (PP) and 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 sowing, when no winter crop is crowing, either 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

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