a conceptual rainfall-runoff simulation model with
a nonlinear reservoir
Totally free download of software
The RainOff computer program, or simulation model,
calculates runoff from rainfall on watersheds
(hydrologic catchment areas) whose extension is
limited by the condition that the rainfall can be
assumed evenly distributed over the area.
The program can be freely downloaded, it is free
shareware in the public domain.
The rainfall is converted into recharge by routing
through a retention reservoir from which water
escapes depending on predetermined characteristcs as
storage capacity, initial storage and maximum rate
of escape (representing evaporation or subsurface
drainage). This first reservoir gives the recharge
(rainfall excess) as overflow.
The recharge is routed through a second, non-linear,
reservoir with a reaction factor whose value depends
on the storage level. Thus, the conversion
(transformation) of rain into runoff (surface
drainage) and flooding is produced.
Modelling with RainOff gives the opportunity of
predicting the hydrology of the watershed
(catchmnent) and of flood forecasting.
The reaction (response) factor can be determined
from recorded rainfall-runoff data. The program uses
various reservoir functions and selects the optimal
function. Alternatively, it is possible to introduce
the reservoir function, together with rainfall data,
and the program will calculate the runoff.
On 12 December 2010 an extra graph was provided for
the recorded rainfall-runoff statistics and trends,
thanks to a suggestion by Mr. Juan Victoria.
On 27 August 2012 the program was updated to include
a quadratic reservoir function and on 1 december
2012 a Help function and an observed-calculated
graph was added.
More details are given in the program itself.
The program starts giving clicking on
More information is given in the program itself.
A lecture note ("Data Analysis") on drainage
research with examples of RainOff applications is
found on the articles
An example of the application of the Curve Number
Method for the design of a surface drainage system
for sugar cane plantations in a humid tropical
coastal area can be found in a chapter
("Agricultural Drainage Criteria"), also on the
reports & cases
reports & cases
Introduction screen of RainOff program
Example of RainOff application