in infowworks ICM you can apply rainfall directly to a 2D mesh you can apply multiple rainfall profiles and infiltration models spatially across the network there are also options to help you streamline separating rainfall applied to the 2D mesh versus subcatchments in integrated models this example shows direct 2D rainfall on a mesh you can see the areas of the mesh that are wet above the theme threshold you can also see where the runoff is converging into flow paths the 2D infiltration model calculates the infiltration properties in 2D elements the areas in the network where infiltration is to be applied are represented either by an entire 2D zone or by infiltration zone 2D objects that you set up if required the volume infiltrated in the 2D surface can be connected to a node two single or multiple links or to a subcatchment in the 1D system by using a permeable zone 2D object when you are applying direct rainfall on the mesh several additional results fields are available to you for viewing in graphs and grids such as this graph for effective infiltration for an element activate the apply rainfall etc directly to mesh elements option in the 2D zone properties to apply direct rainfall to the elements you can also apply rainfall everywhere or outside subcatchments the ladder is useful in integrating modeling to avoid double counting runoff areas a specific rainfall profile and corresponding evaporation profile can be applied to the 2D elements per 2D zone any spatial rainfall profiles will override this value note that a blank infiltration surface will produce 100% runoff the rainfall percentage can be adjusted if appropriate infiltration surface 2D objects are used to define the infiltration characteristics for specific areas typically different surface types an infiltration model is selected for each infiltration surface and the parameters vary based on the infiltration model selected there are five infiltration types which can be applied to the 2D mesh fixed a fixed percentage of the net rainfall that becomes runoff this is set as a value between zero and one the effective infiltration rate is calculated as the rainfall that does not become runoff this is typically applied to impermeable surfaces such as roads constant this is like the fixed model but an additional constant infiltration loss coefficient is defined based on the maximum infiltration rate this can be useful for modeling sustainable drainage structures such as permeable paving deficit and constant loss this method models the surface as a single soil layer in which rainfall is initially stored and is subject to evaporative loss when the soil layer reaches saturation capacity infiltration may occur any excess rainfall goes to runoff horton infiltration on the surface is modeled directly using a variant of the Horton equation which is a formula derived empirically from infiltrometer/ small catchment studies you set an initial infiltration rate a limiting infiltration rate and a decay factor a separate recovery factor can also be set this is typically applied to pvious surfaces such as fields and pastures green amped infiltration on the surface is calculated as a function of the soil suction head parocity hydraulic conductivity and time when using this model for 2D simulations it is possible to set the initial moisture deficit using the same objects as the Horton model moisture deficit values between 0 and 100 can be specified where zero represents a saturated initial condition and 100 represents a dry initial condition infiltration zone 2D objects are used to represent areas of different surface types by a set of non-over overlapping infiltration zones typically a separate infiltration zone is required for impermeable surfaces rural areas and drainage features infiltration zones can be imported via the open data import center or digitized directly on the geoplan an infiltration zone overrides the 2D zone infiltration surface properties it is important that you take care when digitizing your infiltration zones to avoid self-intersecting polygons and hollow polygons these issues are often generated when importing road polygons extracted directly from mapping as such it can help to simplify a model by using the 2D zone infiltration surface field to your advantage and eliminating the need to import roads as a separate set of polygons you can set the 2D zone properties to your road infiltration surface and exclude them from your infiltration zone coverage when using the deficit and constant loss Horton or green amped infiltration models it is necessary to set the initial deficit initial soil water content or soil moisture deficit using a 2D initial condition zone this is a separate polygon type but is most likely a duplicate of your infiltration zones permeable zone 2D objects are used to link infiltrated volume from the 2D surface onto the 1D system infiltrated volume in the permeable zone can drain to a selected node to single or multiple links or to a subcatchment the drainage links for any infiltrated volume can be visually represented on the geo plan as arrows permeable zones can be imported via the open data import center or digitized directly on the geoplan permeable zone parameters are edited in the permeable zone 2D grid window of the polygon's grid or the permeable zone 2D property sheet permeable zone 2D objects can be used for example to model the flow through permeable surfaces that are part of a sustainable drainage structure directed into the drainage system the example shown is one method of representing a filter drain you have the infiltration zone linked to the permeable zone which then drains infiltrated volume into the links permeable zones can cover areas with different infiltration properties and therefore overlap several 2D infiltration zones