The Multi-Hydro model requires several input data. Indeed, each module need to be feed accordingly with the model on which it's based. Also the requirements are detailled below for each parts
The surface module need to be feed with the elevation data, the land use data and the surface properties of the soil:
The elevation need to be given as a raster file containing
the data for each pixel of the modelled area. The elevation is used to define the
slope of the soil to compute the runoff. These data can take into account the location
of the building or not, so will also subject some options in the use of the model.
-Land use and soil properties
The land use correspond in a classification of the different uses
of the modelled area. Each classe is considered as homogeneous, which mean that all the
pixel with the same classe code will have the same hydrological behaviour. For this,
each classe code will return to a set of properties including the Manning coefficient,
the interception depth (the first millimeters of rainwater which will be lost at the
begining of an event), the hydraulic conductivity, the capillary suction and the moisture
deficit. the two first parameters are used to define the runoff and the last three parameters
are used to define the potential infiltration.
The soil data
The soil module represent the water processes in the unsaturated area of the soil. So the
data requiered for this module are the description of the soil (number of layers, porosity, the
soil moisture content and the depth of the water table).
The drainage system data
These data are the description of the sewer system and contain the location of the pipesnand
their connection between themselves, their shape, their depth and the eventual baseflow.
The location of the gullies, making the connection between the surface module and the drainage
module, need to be carefully determined in the modelled area.
The eventual facilities located on the drainage network (pumps, weirs, storage tanks, etc)
will be located and described carefully (fonctionning, capacity, etc).
All these data need to be feed in the Multi-Hydro model according to the formatting requiered
by each module. Nearly all data pre-processing could be done in ArcGIS or QGis (or any GIS
software). With these generic tools, the step of pre-formatting of the data is very repetitive
and data transformation may easily be time consuming. Therefore an advanced and dedicated GIS
data assimilation interface is a requisite to complete a distributed hydrological model that is
both transportable from catchment to catchment and is easily adaptable to the data resolution.
This is achieved both for the cartographic data and the linked information data.
The MH-AssimTool (Multi-Hydro Assimilation Tool) software allows Multi-Hydro users to easily
change the case study and/or to format the input files with new, better adapted grid size data. It allows also to fill the lack in the available data by the use of mean values coming from the litterature.
The visualisation of the results given by the model is an important part of the modelling.
Multi-Hydro provides a sett of procedures to plot the basic outputs of the modelling.
The plot of the discharge is the most common output of a hydrological model. In Multi-Hydro,
two different discharges are given. The first one is the runoff discharge at the surface outlet
of the catchment and for each particular interest point defined by the user. The second one is
the discharge at the outlet of the drainage system.
The surface module provides some results as raster data. It's the case for the overland water
depth and the potential infiltration. These results can be easily used in GIS software, but we
provide also a procedure to plot these map through the Scilab software for each time step of
Currently, some other results given by the model don't still have a plot procedure in
Multi-Hydro. It's the case for the water saturation profile in the soil. These profiles are
given for each pixel of the modelled area. In the drainage system, a lot of data are given for
each pipe and each junction between these pipes (water depth, inflow, outflow, overflow).
These results can be used to produce the water balance in the system.