Agricultural Waterlogging, Soil Salinity, Field Irrigation, Plant Growth, Subsurface Drainage, Groundwater Modelling, Surface Runoff, Land Reclamation, and other Crop Production and Water Management Issues in Agriculture
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The purpose of this web site is to share my experiences with workers in any country on waterlogging in agricultural lands, irrigation induced soil salinization (salination), subsurface drainage for agriculture (horizontal and vertical), reuse of groundwater hydraulics, (geo)hydrology, rainfall and surface runoff relations, reclamation and improvement of waterlogged saline (salty), sodic alkaline, and acid sulphate (sulfate) soils, plant growth, crop production and responses as well as statistical analysis consisting of segmented linear regression and cumulative frequency distributions.
The site aims at contributing to environmentally sound water-management for the control of salinity, water-logging and depth of water-table in agricultural land thus enhancing soil conservation and sustainable land use.

As a land and watermanagement specialist at the International Institute for Land Reclamation and Improvement (ILRI), Wageningen, The Netherlands, I have worked since 1965 in almost 30 countries in Asia, Africa and Latin America, giving training courses, participating in research programs and providing project advice as a consultant. In 2002, I left ILRI to be independent.

When you wish to communicate with the author, please use the contact form.
Languages: Dutch, English and Spanish.
Messages in French, German or Portuguese will be understood but replied in English or Spanish.

& models

General articles
& manuals

(in Spanish,
 en Español)

reports & cases

reports & cases

& answers


What is offered?
Pages with software,
articles and FAQ's
arranged by subject :


drainage subjects
ground water
& aquifers

irrigation subjects
tidal/spate irrigation

soil subjects
salinity, alkalinity
& sulfate acidity

statistical subjects
cumulative frequency
& segmented regression

Free downloads of software
The site gives free download opportunity of software and models freeware and computer programs (tools I developed because of need in my work).
       The programs relate to statistics (segmented linear regression with break-point, cumulative frequency analysis and recurrence predictions), groundwater flow to subsurface drains (horizontal/tile drainage) and pumped tubewells (vertical drainage), rainfall-surface runoff relations simulated with a nonlinear reservoir, and agro-hydro-salinity simulation models including groundwater hydraulics in unconfined and semiconfined aquifers.
       See further down for more information

Free downloads of general articles
The site offers free downloading of general articles and manuals in the field of waterlogging, agricultural land drainage for soil desalination (desalinization), salty soils, and subsurface drainage for agriculture (horizontal and vertical).
       In addition one can find here supporting papers on the software referring to land reclamation (rehabilitation) of waterlogged land, and the remediation (restoration) of salt affected, saline, soils. The same holds for the models on statistical analysis, segmented linear regression of plant growth, crop production and yield responses, as well as cumulative frequency distributions of hydrologic factors.

Reports and case studies
A list of project evaluations and case studies on water-management, agricultural land drainage, irrigation, drainage for salinity control in agriculture for remediation of soil salination (salinisation) can be found on the published reports page and on the particular reports page.
       The same holds for reclamation, rehabilitation, restoration and improvement of salty, saline, alkaline and acid sulphate/sulfate soils

Answers to frequently asked questions
Frequently asked questions, often on irrigation, soil salinity, alkalinity and acidity (i.e. saline, salty, alkali, alkaline sodic and acid sulphate/sulfate soils), land rehabilitation and remediation are answered on the faq's page with papers and lecture notes.
       Further, one may find here the answers to questions on the selection of land drainage systems in agriculture, on the determination of hydraulic conductivity, on interception drainage, on subsurface drains in sloping land, and on downstream river salinity.

I intend to update and expand this website regularly and include update reports.

Experiences were hammered in



One depends on many  

Software in brief

See also the



Experiences are automatic


Segmented (piecewise, in splines) linear regression using a breakpoint and confidence intervals (limits, belts, bands). Two independent (explanatory) variables (predictors) are allowed.
Cumulative frequency analysis with probability distribution fitting, prediction of recurrence interval and return period.
Subsurface drain spacing equations and depth of water table based on the energy balance of groundwater flow.
Well spacing equations for subsurface drainage and drawdown of the watertable.
Rainfall-runoff relations of a watershed (catchment area) using the concept of a non-linear reservoir to simulate surface drainage processes.
Drainage and soil salinity model based on water and salt balances (budgets) of irrigated land to simulate watertable and soil salinity control. See table of contents of the manual.
        In October 2012, a simpler version of SaltMod was made by the name of SaltCalc, which lacks the crop rotation and farmers' response options but permits monthly instead of seasonal calculations.
        In April 2013, a similar program LeachMod was introduced. It is useful to simulate the results of field experiments on leaching of saline soils whereby the soil salinity was monitored. As all the input data for each time step are entered in tables, the program does the work for all the time steps in one go. It will also automatically detect the optimal value of the leaching efficiency.
A polygonal combination of the drainage and soil salinity model SaltMod combined with model of groundwater flow to simulate the influence of aquifer conditions on watertable and soil salinity control. See table of contents of the manual.

In addition, four Calculators are availabe:
- an alternative extended calculator able to perform multiple transformations on and operations with two variables, while the intermediate results can be stored for further action.
- a two-way F-test calculator for use in significance testing in regression analysis through the Anova (analysis of variance) table: F-test-value => probability, and probability => F-test-value.
- a two-way standard normal distribution calculator that quickly gives the probability of a stochastical variable and vice versa.
- a two-way t-distribution calculator to perform a t-test on the significance of the difference between means (averages) of series of data using Student's t- probability distribution : t-test-value => probability, and probability => t-test-value.


A consultant learns from others









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