Simpel - Soil water models

This is a short introduction to the SIMPEL-model family of soil water models


Full version


Old Download version

  • Basic version (prak96english.xls)  translated to give you an impression. Frequently used in entry-level courses of hydrologic modelling


What are the SIMPEL models ?

SIMPEL are simple soil water models in Excel. You can use them to calculate the soil water balance (evaporation, seepage, soil water content) of a soil column.

The SIMPEL models share a common policy: they cover the lowest, serious end of hydrologic computing. The beginning of the SIMPEL familiy was the need for a simple soil water model in ecological education which could be used immediately without fuzzing around with strange format parameters and incomplete data sets. To work with SIMPEL, you start EXCEL, load the worksheet and play with it.



How can I get them ?

All SIMPEL models are located on this server. However, if you want something physical to show it to your girlfriend or your children I can write the contents of this server to a CD-ROM and mail it to you.


How much do they cost ?

Nothing. As long as I am employed by my university 8-).


I do not speak German ?!

Oops. Urgh. Sigh. You have a problem. You should seriously consider learning the language of Goethe, Marx and Hitler. It might enlarge your spirit more than any other language, except perhaps chinese, greek, french, italian etc. 8-).

But - it could be worse. Despite the fact that most pieces of SIMPEL are in German language, the models themselves are fairly simple to understand - at least for someone with some knowledge of soil science or hydrology.

I will try to keep at least the models up to date and work on a short summary of the documentation - but life is short and time is scarce. The only thing to change this policy would be an invitation for 3 months from a foreign university where life is fairly easy to write english documentation  8-).



What about copyright ?

SIMPEL belongs to the GNU software family under the GNU Copyleft. You are free to use the models and even to change them - as long as you do not charge money for it. As usual, I will take no responsibility at all for whatever might happen to you if you are using SIMPEL models.


The SIMPEL models

As long as I do not have an english version of the models, the links point to the german spreadsheets.


Simpel Version 1

The first version integrates evaporation, soil water models and data input into one single file.

  • single layer
  • model for wetlands and other field with high water table
  • documentation for all versions (PDF-File) - still in German language.

Simpel Version 2

This new version is more complex, but still manageable. The input is now separated from the module for evaporation and the soil water model. The evaporation module contains the most common german methods to calculate evaporation (including Penman). The Penman/Monteith method was taken from the EPIC-models.

The model consists now of the following components:

The version and its documentation are still not perfect - but if Microsoft releases a text processor unable to deal with more than 20 pages of scientific text I am in good company. Hints and suggestions are welcome.

Revision history



  • Hörmann, G., 1997: SIMPEL - ein einfaches, benutzerfreundliches Bodenwassermodell zum Einsatz in der Ausbildung. Deutsche Gewässerkundliche Mitteilungen 41(2):67-72, (PDF-Version), ein Vergleich mit einem Richards-Modell
  • Hörmann, G., 1998: The SIMPEL soil water spreadheets: defining the low end of hydrologic computing. Unpublished (PDF-Version).
  • Hörmann, G., X. Zhang and N. Fohrer (2007): Comparison of a simple and a spatially distributed hydrologic model for the simulation of a lowland catchment in Northern Germany. Ecological Modelling, 209 (1): 21-28. (ISI 1,88).
  • Hörmann, G., N. Köplin, Q. Cai, N. Fohrer, 2009: Using a simple model as a tool to parametrize the SWAT model of the Xiangxi river in China. Quaternary International 208: 116-120.