Search found 4919 matches

by Jirka
Thu May 28, 2020 10:06 pm
Forum: HYDRUS (2D/3D)
Topic: Discrepency between Variable Boundary Input and Total Surface Flux
Replies: 3
Views: 21

Re: Discrepency between Variable Boundary Input and Total Surface Flux

Hydrus assumes that atmospheric fluxes are vertical, not perpendicular to a sloping boundary, and thus are perpendicular to the horizontal projection of the atmospheric boundary. Rainfall is measured on a vertical plane, right?

J.
by Jirka
Thu May 28, 2020 3:17 pm
Forum: HYDRUS (2D/3D)
Topic: Discrepency between Variable Boundary Input and Total Surface Flux
Replies: 3
Views: 21

Re: Discrepency between Variable Boundary Input and Total Surface Flux

The CumQAP column simply integrates the cumulative potential surface flux [int(Evap-Prec)dt] as defined at the input. Thus if this column shows a different value than you expect, then your input must be wrong. J.
by Jirka
Wed May 27, 2020 4:10 pm
Forum: Hydrus 1D
Topic: Snow Precipitation Equivalent
Replies: 4
Views: 29

Re: Snow Precipitation Equivalent

The code should give you the SnowLayer exactly 1 cm (water equivalent). See attached test example. J.
00.zip
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by Jirka
Wed May 27, 2020 2:56 am
Forum: Hydrus 1D
Topic: Snow Precipitation Equivalent
Replies: 4
Views: 29

Re: Snow Precipitation Equivalent

The snowfall should be entered in the "snow water equivalent", which is the amount of water contained within the snowpack. Since new powdery snow has a snow water density of about 10%, 1 cm of "snow water equivalent" would correspond to 10 cm of the snowpack. J.
by Jirka
Sun May 24, 2020 7:39 pm
Forum: Hydrus 1D
Topic: Field data optimization
Replies: 1
Views: 35

Re: Field data optimization

1. It is a common practice to use one season for calibration and one for validation. 2. For reason of uniqueness, we do not recommend to optimize many parameters simultaneously. See, for example, Hopmans, J. W., J. Šimůnek, N. Romano, and W. Durner, Inverse Modeling of Transient Water Flow, In: Meth...
by Jirka
Fri May 22, 2020 12:32 am
Forum: Hydrus 1D
Topic: rRoot (T-level)/Transp (Meteo_out)
Replies: 5
Views: 74

Re: rRoot (T-level)/Transp (Meteo_out)

In general, they should be the same. However, they can be different for some special conditions, such as when you consider interception. Meteo.out reports potential transpiration values calculated based on meteo conditions. T_level.out reports potential transpiration values as applied to root water ...
by Jirka
Thu May 21, 2020 9:10 pm
Forum: Hydrus 1D
Topic: Inpact of water content on heat transport
Replies: 6
Views: 447

Re: Inpact of water content on heat transport

It seems that you have no idea what Hydrus actually does. Perhaps, you should first do some tutorials before you start asking further questions. CSIRO Tutorial eBook: https://www.pc-progress.com/Downloads/Public_Lib_H1D/HYDRUS-1D_Tutorial_V1.00_2018.pdf Rassam, D., J. Šimůnek, D. Mallants, and M. Th...
by Jirka
Thu May 21, 2020 5:12 pm
Forum: Hydrus 1D
Topic: rRoot (T-level)/Transp (Meteo_out)
Replies: 5
Views: 74

Re: rRoot (T-level)/Transp (Meteo_out)

"rRoot" in the T_level.out file and "Trasp" in the Meteo.out file are potential transpiration rates in units of [L/T] and (mm/d). respectively. This means that they should be on the order of few mm/d. I do not see how they can potentially be 1400 or 1900 m (wrong units and wrong values). J.
by Jirka
Tue May 19, 2020 6:35 pm
Forum: HYDRUS (2D/3D)
Topic: Constant Head BC Ditch & Fluctuating GWT
Replies: 9
Views: 629

Re: Constant Head BC Ditch & Fluctuating GWT

I have no more comments. To me, it seems that if you control pressure heads at the bottom of the transport domain and in the two ditches on the side, it should be pretty straightforward to control the pressure head gradients throughout the domain. I wonder if you somehow misinterpret how HYDRUS work...
by Jirka
Tue May 19, 2020 5:56 pm
Forum: Hydrus 1D
Topic: Inconsistency in flow simulation with pond in soil columns
Replies: 3
Views: 116

Re: Inconsistency in flow simulation with pond in soil columns

The problem with your project is that the entire soil column gets fully saturated and the free drainage BC is not appropriate BC for such conditions. See our description of this BC in the help: "A zero-gradient boundary condition can be used to simulate a freely draining soil profile. Such a situati...
by Jirka
Mon May 18, 2020 11:52 pm
Forum: Hydrus 1D
Topic: rRoot (T-level)/Transp (Meteo_out)
Replies: 5
Views: 74

Re: rRoot (T-level)/Transp (Meteo_out)

First question: I do not see the difference between rRoot (1400 mm) and the transpiration in Meteo_out (1400 mm).

Another question: Unless you use an option when you specify directly net radiation, you need to use Julian days since radiation is then calculated based on that.

J.
by Jirka
Mon May 18, 2020 4:02 pm
Forum: Hydrus 1D
Topic: numerical solution is not converged
Replies: 1
Views: 88

Re: numerical solution is not converged

When you have the n parameter less than 1.1, you should use the VGM model with an air-entry value of -2 cm, since the standard VGM model provides erroneous predictions of the conductivity function (for fine-textured soils with low n values). The inverse algorithm does not check the physical correctn...
by Jirka
Mon May 18, 2020 3:50 pm
Forum: Hydrus 1D
Topic: Inconsistency in flow simulation with pond in soil columns
Replies: 3
Views: 116

Re: Inconsistency in flow simulation with pond in soil columns

When you consider the surface layers, you need to have a higher precision in terms of the pressure head (e.g., 0.1 cm). See the attached modified project. J.
by Jirka
Fri May 15, 2020 5:26 pm
Forum: Hydrus 1D
Topic: Snow Hydrology Discrepancies
Replies: 5
Views: 198

Re: Snow Hydrology Discrepancies

No, it does not do it for metro variables if you do not select this option (in the Time Information window). However, it does it for temperatures if you specify "Interval for Temperature cycle" larger than zero in the Heat Transport Parameters window and Ampl in Time Variable Condition window. J.
by Jirka
Thu May 14, 2020 10:26 pm
Forum: Hydrus 1D
Topic: Snow Hydrology Discrepancies
Replies: 5
Views: 198

Re: Snow Hydrology Discrepancies

If there is one couple of values T_min and T_max for each day, then temperature varies between these two values following a sine wave. If T_min and T_max are the same, then indeed, there is only one temperature for the entire day. J.