Identification and regionalization of dominant runoff processes – a GIS-based and a statistical approach

Abstract

Abstract. In this study two approaches are presented to identify Dominant Runoff Processes (DRP) with respect to regionalization. The approaches are a simplification of an existing method to determine DRP by means of an extensive field campaign. The first approach combines the permeability of the substratum, land-use and slope of the basin in a GIS-based analysis. The second approach makes use of discriminant analysis of the physiographic characteristics of the basin and links it to the GIS analysis. The results of the developed approaches are maps, which identify dominant runoff processes and represent a spatial distribution of the hydrological behaviour of the soil during prolonged rainfall events. The approaches have been developed in a micro-scale basin (Germany). An additional meso-scale basin was introduced in which the two approaches were applied for quality control. The thus generated maps for the micro-scale basin were compared with an existing DRP map, which was derived with the existing method. The first approach showed a resemblance of 79% when compared to this map, whereas the second approach showed only a resemblance of 51%. The generated maps for the meso-scale basin were compared to DRP that were determined point wise according to the existing method. The first approach showed in this case a resemblance of 81%, whereas the second approach showed a resemblance of 68%. Therefore, the first approach is preferred to the second approach when accuracy, data input and calculation time are concerned.

Identifying Dominant Runoff Processes at a Regional Scale – A GIS - Based Approach

“…However, the approach developed by Scherrer and Naef (2003) based on large number of field-and sprinkling experiments formed the basis for developing process decision schemes to determine DRPs on a soil profile which occur after prolonged rainfall events. The data required for the method comprise sixteen (16) datasets: soil profiles; soil maps; topographical maps; geo-morphological maps; vegetation maps; geological maps; hydrological maps; geo-technical maps; geo-ecological maps; drilling points with soil description; infiltration tests; digital maps (ATKIS); forestry maps; agricultural land evaluation; remote sensing data and drainage plans (Müller et al, 2009). Scherrer and Naef (2003) indicated the limitations of their approach is that rains of low intensity infiltrate into the soil predominantly by matrix flow and their scheme does not apply to such conditions.…”

“…Several runoff processes can occur on one site, however the dominant one is that which contributes most to runoff, hence other processes can be neglected (Müller et al, 2009;Scherrer and Naef, 2001). Theprocess which dominates depends on the site characteristics and the rainfall event.…”

“…Automatic approaches differ in the type of data requirement. Some rely solely on topographic information (Gharari et al, 2011) while others employ all available information (Schmocker-Fackel et al, 2007) The result of both manual and automated approaches is a DRP-map which represent the spatial distribution of the hydrological behaviour of the soil during prolonged rainfall events (Müller et al, 2009 (Antonetti et al, 2016), where the numbers from 1 to 3 represent the delay in their reaction to rainfall, with 1 representing an almost immediate reaction, 2 a slightly delayed one, and 3 a strong delayed one (Müller et al, 2009;Scherrer and Naef, 2003;Schmocker-Fackel et al, 2007).…”

“…In this study, DRP was evaluated using GIS-based automatic geostatistical (GIS-DRP) approach developed by Müller et al (2009). This approach was preferred because it requires less input data as well as shorter computation time with higher accuracy when compared to other GIS based approaches (Müller et al, 2009).…”

“…This approach was preferred because it requires less input data as well as shorter computation time with higher accuracy when compared to other GIS based approaches (Müller et al, 2009). …”