Imperviousness. This hydrologic variable establishes the degree to which water can potentially penetrate into the ground at any given location. One hundred percent imperviousness means no water can infiltrate while zero percent indicates all precipitation can infiltrate. The actual infiltration rate is governed by factors such as the state the soil’s saturation level and the type of land cover. Level of Service: This expression is a water resources design criteria used to establish the conveyance capacity of drainage systems. It is often expressed in terms of “Return Period” (Years). Higher “Levels of Service” translate into larger flow conveyance capacities. Model: In this document, a model is a mathematical representation of real world processes in a computer form. Hydrologic models for example, simulate the hydrologic cycle. There is a plethora of hydrologic models available today ranging from simple mathematical abstractions of the real world to highly detailed renditions of the hydrologic cycle.
Imperviousness. Built-up areas are characterized by the substitution of the original (semi-)natural cover or water surface with an artificial, often impervious, cover. These artificial surfaces are usually characterized by long cover duration (FAO Land Cover Classification System, 2005)23. A high resolution imperviousness dataset with all artificially sealed areas will be produced (0-100% and change detection 0-100%) using automatic derivation based on calibrated NDVI. A per-pixel estimate of imperviousness is foreseen as the index for the degree of artificial soil sealing. Data for 2006 and 2009 were produced in the frame of GMES precursor activities and Geoland-2, and are provided by EEA. Re-analysis is needed to keep consistency in the time series. The processing scheme is based on the experiences of the 200624 and 2009 exercises and the results of the product validation. Statistical validation will be carried out on the 100m x 100m data. Minimum overall accuracy shall be 85% with > 90% as the overall target.
