Different Approaches to Estimation of Drainage Density and Their Effect on the Erosion Potential Method

Nevena Dragičević,Barbara Karleuša,Nevenka Ožanić

doi:10.3390/w11030593

Abstract

This paper analyses the possibilities of improving the precision of, and obtaining better, drainage density (Dd) input data for the Erosion Potential Method (EPM). This method is used for erosion assessments in karst areas that are characterised by torrential watercourses. The analysis is conducted in the Dubračina catchment in Croatia. Four different methodologies are used to derive a Dd map. The approaches use different assumptions and allow different spatial variability. The first two are commonly applied in the EPM. The Dd in the first case scenario corresponds to very low Dd and is homogenous throughout the entire catchment. In the second case, Dd is calculated on the sub-catchment level and varies from very low to medium. The third and fourth case scenarios provide the most spatially variant maps. The output of the third case is the actual Dd based on a topographic map, and the fourth potential Dd is based on a river network map derived from a Lidar digital elevation model. The third and fourth case scenarios provide better spatial variability for the Dd parameter, and both case scenarios are considered appropriate input data for the EPM and an improvement of the accuracy and precision of the EPM.

Highlights

One drainage basin attribute of particular importance for this research is drainage density.Drainage density, Dd, is defined as the total length of channels per unit area [1], and it describes the drainage spacing and distribution in a catchment [2]
The output of the third case is the actual Dd based on a topographic map, and the fourth potential Dd is based on a river network map derived from a Lidar digital elevation model
It is known that low values for drainage density can indicate different characteristics, such as higher infiltration rates, lower surface flow velocities and/or lower values of sediment yield transported through river networks, all of which do not necessarily relate to the Slani potok and Mala Dubračina sub-catchments, which are two of the most severely affected sub-catchments by erosion processes (Figure 2)

Summary

Introduction

Dd , is defined as the total length of channels per unit area [1], and it describes the drainage spacing and distribution in a catchment [2]. According to Prabu and Baskaran [5], drainage density is expressed as the distance between the streams and reflects the soil structure in the catchment. This parameter is not constant over time; it evolves as the drainage system in a catchment evolves [6]. This attribute of a drainage basin provides a useful numerical measure of landscape dissection and runoff potential to hydrologists and geomorphologists

Methods

Results

Conclusion