start:hype_model_description:hype_human_water
Differences
This shows you the differences between two versions of the page.
| Both sides previous revision Previous revision Next revision | Previous revision Next revision Both sides next revision | ||
|
start:hype_model_description:hype_human_water [2018/09/07 16:08] cpers [Links to file reference] |
start:hype_model_description:hype_human_water [2018/10/12 13:59] cpers [Irrigation water demand] |
||
|---|---|---|---|
| Line 21: | Line 21: | ||
| \\ | \\ | ||
| - | ==== Links to file description ==== | + | ==== Links to file reference ==== |
| ^Parameter/Data ^File ^ | ^Parameter/Data ^File ^ | ||
| Line 57: | Line 57: | ||
| For non-submerged crops, the calculations are based on the FAO-56 crop coefficient methods (Allen et al., 1998). The dual crop coefficient method is used because it is more specific than the single crop coefficient method, and more suitable for daily water balance models. Since transpiration is of primary interest in estimating crop water demand, the irrigation routine focuses on estimating potential transpiration (<m>T_P</m>) with the basal crop coefficient (<m>K_{CB}</m>) and the reference potential crop evapotranspiration (<m>ET_0</m>): | For non-submerged crops, the calculations are based on the FAO-56 crop coefficient methods (Allen et al., 1998). The dual crop coefficient method is used because it is more specific than the single crop coefficient method, and more suitable for daily water balance models. Since transpiration is of primary interest in estimating crop water demand, the irrigation routine focuses on estimating potential transpiration (<m>T_P</m>) with the basal crop coefficient (<m>K_{CB}</m>) and the reference potential crop evapotranspiration (<m>ET_0</m>): | ||
| - | <m> T_P=K_{CB}×ET_0 </m> | + | <m> T_P=K_{CB}*ET_0 </m> |
| ET0 follows the dynamics described above (<m>ET_0 = epot</m> here following Wisser et al. (2008)). KCB depends on crop type and phenological stage, which is defined in CropData.txt. KCB is constant during the initial development stage, then increases linearly during the development stage until it reaches the mid-season stage during which it is again constant. Finally, <m>K_{CB}</m> decreases linearly from the end of the mid-season stage until the end of the season. The dynamics of <m>ET_0</m> and <m>K_{CB}</m> produces a dynamic <m>T_P</m> profile (Figure 1). Allen et al. (1998) provide indicative values for <m>K_{CB}</m> (cf. their Table 17). | ET0 follows the dynamics described above (<m>ET_0 = epot</m> here following Wisser et al. (2008)). KCB depends on crop type and phenological stage, which is defined in CropData.txt. KCB is constant during the initial development stage, then increases linearly during the development stage until it reaches the mid-season stage during which it is again constant. Finally, <m>K_{CB}</m> decreases linearly from the end of the mid-season stage until the end of the season. The dynamics of <m>ET_0</m> and <m>K_{CB}</m> produces a dynamic <m>T_P</m> profile (Figure 1). Allen et al. (1998) provide indicative values for <m>K_{CB}</m> (cf. their Table 17). | ||
| Line 67: | Line 67: | ||
| - | <m> if H <(S_{SW}×P_{SSWCORR}×AWC) right irrigate </m> | + | <m> if H <(S_{SW}*P_{SSWCORR}*AWC) right irrigate </m> |
| H is the plant-available soil moisture (i.e. soil water above //wcwp1// and //wcwp2// in soil layers 1 and 2 respectively). //AWC// is the maximum plant-available water content in soil layers 1 and 2 (i.e. the sum of //fc1// and //fc2//). <m>S_{SW}</m> is a fraction of //AWC// (defined upwards from //wcwp//). Below <m>S_{SW}</m> the crop experiences water stress, creating a need for irrigation. <m>S_{SW}</m> varies from day to day and depends on the crop type and <m>T_P</m>: | H is the plant-available soil moisture (i.e. soil water above //wcwp1// and //wcwp2// in soil layers 1 and 2 respectively). //AWC// is the maximum plant-available water content in soil layers 1 and 2 (i.e. the sum of //fc1// and //fc2//). <m>S_{SW}</m> is a fraction of //AWC// (defined upwards from //wcwp//). Below <m>S_{SW}</m> the crop experiences water stress, creating a need for irrigation. <m>S_{SW}</m> varies from day to day and depends on the crop type and <m>T_P</m>: | ||
| - | <m> S_{SW}=1-(DL_{ref}+0.04×(5-{{T_P}/0.95})) </m> | + | <m> S_{SW}=1-(DL_{ref}+0.04*(5-{{T_P}/0.95})) </m> |
| <m>DL_{ref}</m> is a crop-type specific reference depletion level (essentially the fraction of //AWC// that can be depleted before stress occurs, defined downwards from //wcfc//). Allen et al. (1998) provide indicative values for <m>DL_{ref}</m> (cf. their Table 22). The <m>S_{SW}</m> equation is a slightly modified form of the original FAO-56 equation to account for the fact that only <m>T_P</m> is used here. A typical <m>S_{SW}</m> profile is shown in Figure 3.1. By default, <m>S_{SW}</m> is limited to the range 0.2 – 0.9, but it can be further refined with the parameter <m>P_{SSWCORR}</m> (//sswcorr// in par.txt) to maximum 1. | <m>DL_{ref}</m> is a crop-type specific reference depletion level (essentially the fraction of //AWC// that can be depleted before stress occurs, defined downwards from //wcfc//). Allen et al. (1998) provide indicative values for <m>DL_{ref}</m> (cf. their Table 22). The <m>S_{SW}</m> equation is a slightly modified form of the original FAO-56 equation to account for the fact that only <m>T_P</m> is used here. A typical <m>S_{SW}</m> profile is shown in Figure 3.1. By default, <m>S_{SW}</m> is limited to the range 0.2 – 0.9, but it can be further refined with the parameter <m>P_{SSWCORR}</m> (//sswcorr// in par.txt) to maximum 1. | ||
| Line 83: | Line 83: | ||
| (3) Up to a defined fraction of <m>S_{SW}</m> (<m>P_{iwdfrac}</m>, //iwdfrac// in par.txt): | (3) Up to a defined fraction of <m>S_{SW}</m> (<m>P_{iwdfrac}</m>, //iwdfrac// in par.txt): | ||
| - | <m>W_{I,D,j}=min[(S_{SW}×P_{SSWCORR}×AWC-H)×P_{iwdfrac},(AWC-H)]</m> | + | <m>W_{I,D,j}=min[(S_{SW}*P_{SSWCORR}*AWC-H)×P_{iwdfrac},(AWC-H)]</m> |
| The fraction can be larger than 1. For example, to irrigate to a level 10% above <m>S_{SW}</m>, <m>P_{iwdfrac}</m> =1.1. <m>W_{I,D,j}</m> is, however, limited to <m>AWC</m>. | The fraction can be larger than 1. For example, to irrigate to a level 10% above <m>S_{SW}</m>, <m>P_{iwdfrac}</m> =1.1. <m>W_{I,D,j}</m> is, however, limited to <m>AWC</m>. | ||
| Line 283: | Line 283: | ||
| ==== Links to file reference ==== | ==== Links to file reference ==== | ||
| - | ^Section ^Symbol ^Parameter/Data ^File ^ | + | ^Section ^Parameter/Data ^File ^ |
| - | |Nutrient point sources| |//subid, ps_vol, ps_type, ps_tpconc, ps_tnconc, ps_infrac, ps_spfrac, fromdate, todate//|[[start:hype_file_reference:pointsourcedata.txt|PointSourceData.txt]]| | + | |Nutrient point sources|//subid, ps_vol, ps_type, ps_tpconc, ps_tnconc, ps_infrac, ps_spfrac, fromdate, todate//|[[start:hype_file_reference:pointsourcedata.txt|PointSourceData.txt]]| |
| - | |Tracer T2 (water temperature) point sources| |//subid, ps_vol, ps_type, ps_t2, fromdate, todate//|:::| | + | |Tracer T2 (water temperature) point sources|//subid, ps_vol, ps_type, ps_t2, fromdate, todate//|:::| |
| - | |Tracer T1 point sources| |//pstype=0//|:::| | + | |Tracer T1 point sources|//pstype=0//|:::| |
| - | |:::| |//subid, ps_vol, ps_t1, fromdate, todate, ps_source//|:::| | + | |:::|//subid, ps_vol, ps_t1, fromdate, todate, ps_source//|:::| |
| - | |Negative point source| |//subid, ps_vol, fromdate, todate, ps_source//|:::| | + | |Negative point source|//subid, ps_vol, fromdate, todate, ps_source//|:::| |
start/hype_model_description/hype_human_water.txt · Last modified: 2024/02/21 09:14 by cpers
Except where otherwise noted, content on this wiki is licensed under the following license: CC Attribution-Share Alike 4.0 International
