This adds additional complexities to the hydrologic effects and antecedent moisture effects such as the saturation levels of the soils in the subsurface, groundwater levels, and subsurface hydraulics.
12.
"' Antecedent moisture "'is a term from the fields of hydrology and sewage collection and disposal that describes the relative wetness or dryness of a infiltration.
13.
It is the pervious runoff that is affected by antecedent moisture conditions, as runoff from impervious surfaces such as roads, sidewalks, and roofs will not be significantly affected by preceding moisture levels.
14.
Antecedent moisture is a term that describes the relative wetness or dryness of a sewershed, which changes continuously and can have a very significant effect on the flow responses in these systems during wet weather.
15.
Rainfall-dependent inflow and infiltration ( RDII ) into sewer systems is highly affected by antecedent moisture conditions, and these effects can be more complex than the rainfall / runoff relationships for surface water.
16.
Data-based approaches based on system identification, such as the i3D antecedent moisture model, have been applied to hydrologic modeling for simulating antecedent moisture effects on wet weather events in sanitary collection systems.
17.
Data-based approaches based on system identification, such as the i3D antecedent moisture model, have been applied to hydrologic modeling for simulating antecedent moisture effects on wet weather events in sanitary collection systems.
18.
Traditional approaches for analyzing antecedent moisture effects rely on physically-based models derived from first principles, such as the principles of energy, momentum, and continuity, which rely on measurements of many parameters for input and simulation.
19.
Pervious surfaces ( such as fields, woods, grassed areas, and open areas ) are highly affected by antecedent moisture conditions, as they will produce a greater rate of runoff when they are wet than when they are dry.
20.
However, the great number of parameters in these models, the difficulty of measuring the many parameters, and the sensitivity of the model output to slight variations in the parameters makes using these models to simulate antecedent moisture in sewer systems challenging.
