Drainage network detection and assessment of network storage capacity in agrarian landscape

Abstract

Drainage networks in agrarian landscape withinfloodplains constitute surface’s discontinuities that are expected to affect hydrological response during floods. Drainage network recognition and quanti fi cation of water storage capacity within channels are, therefore, crucial for watershed planning and management. These evaluations require accurate spatial information for the area of interest and in most cases, when studying large catchments, broad datasets of ditches locations and descriptions are not available. In order to characterize drainage networks for large areas, the availability of high resolution topography derived by airborne laser scanner (LiDAR) represents a new and effective tool. Nowadays LiDAR DTMs covering large areas are readily available for public authorities, and there is a greater and more widespread interest in the application of such information for the development of automated methods aimed at solving geomorphological and hydrological problems. While LiDAR DTMs reliability in steep landscape has been proven by several recent studies, only few researches have been conducted to take into account the effectiveness of these data in agrarian low relief landscapes. The goal of this research is to propose a semi-automatic approach based on a LiDAR DTM to (1) detect drainage networks in agrarian/ fl oodplain contexts, and (2) to estimate some of the network summary statistics (network length, width, drainage density and storage capacity). The procedure is applied in two typical alluvial-plain areas in the North East of Italy, and tested comparing automatically derived network with surveyed ones. The results underline the capability of high resolution DTMs for drainage network detection and characterization in the context of agrarian landscapes within floodplains, opening at the same time new challenges to evaluate some hydrological processes in these areas

Land use change in the Veneto floodplain and consequences on minor network drainage system

“…Since drainage networks in agrarian landscapes within floodplains are expected to affect hydrological response during floods (Cazorzi et al, 2013) channel storage capacity can i) outline areas whose hydrological behavior is potentially critical during floods, where land use might increase the level of risk, and ii) they allow to identify storage volumes already available on the surface that can contribute to laminate flood peaks. Therefore this work provides an additional proof of suitability of the estimated network parameters (drainage density and storage capacity) in supporting flood management.…”

“…At first, a semi-automatic approach, developed by Cazorzi et al, 2013, has been applied in order to identify the minor drainage network system and estimate some its parameters such as drainage density and storage capacity, through the DTM which dates back to 2006 and a morphological parameter named Relative Elevation Attribute (REA) derived from it. A thresholding approach based on the standard deviation of REA has been used in order to automatically extract the small-scale topography features (minor drainage network system) (Figure 1).…”

“…The principal causes can be generally distinguished between problems related to large rivers unable to manage the incoming flows, and issues directly related to the inability of draining meteoric water through the smaller hydraulic network (ditches). While problems related to the large rivers are mainly connected to choices and actions applied in historical times, the problems of the smaller hydraulic network are due to small and relatively recent territorial changes: fast human settlement in floodplain, and the intense urbanization, have reduced the extent of the network while increasing at the same time impermeable surfaces, with the result that the remaining network drainage capabilities are no longer sufficient (Cazorzi et al, 2013). As a consequence, situations of hydraulic crisis happen with increasing frequency and they affect the most urbanized districts.…”

“…The study area has been selected because of its involvement in the major flood of 2010 and because of the availability of data, including historical aerial photographs, historical information, and a high resolution LiDAR Digital Terrain Model (DTM). In particular, many recent studies have proved the reliability of these models in many disciplines concerned with Earth-surface representation and modeling, including applications in hillslope (Tarolli and Tarboton, 2006;Lashermes et al, 2007;Booth et al, 2009;Kasai et al, 2009;Tarolli and Dalla Fontana, 2009;Orlandini et al, 2011) and fluvial environments (Charlton et al, 2003;Heritage and Hetherington, 2007;Hilldale and Raff, 2008;Jones et al, 2007;Cavalli et al, 2008;Vianello et al, 2009;Notebaert et al, 2009;Cavalli and Tarolli, 2011;Legleiter, 2012;Cazorzi et al 2013). There is also a growing interest in the application of such information by agencies responsible for land management for the development of automated methods aimed at solving geomorphological and hydrological problems.…”

Perspective – synthetic DEMs: A vital underpinning for the quantitative future of landform analysis?

“…Brummer and Montgomery, 2003;Wohl, 2004;Sofia et al, 2015), and channel networks are identified to evaluate hydrological responses in floodplains (e.g. Cazorzi et al, 2013). Continuous measures such as curvature can arguably distinguish dominant geomorphic processes (e.g.…”