Flood Analysis Supported by Low‐cost Geometric Modelling

Abstract

Today, it is increasingly clear that non‐stationarity hydrological and hydraulic variables and processes are occurring largely because of global warming. Accordingly, extreme hydrological events are becoming more common over time, and their effects are creating greater negative impacts on the environment (fluvial geomorphology and floodplains) and society (flood damage). Given this situation, the implementation of adaptation‐mitigation measures is vital, as well as an increased knowledge of the interaction between water and physical environments. In the binominal water‐terrain, having a reliable digital elevation model (DEM) is essential because of its important influence on fluvial modelling. However, this is frequently a technical‐economic problem. The aim of this paper is first to evaluate the compatibility between hydraulics and geometrics for fluvial applications and second to determine the quality of a novel DEM by robust estimators. This was obtained through the photogrammetric processing of digital aerial images acquired from a low‐cost camera mounted on an alternative aerial platform. Flood modelling and hydraulic parameters were obtained with the assistance of photogrammetric DEM (mesh size: 0.15 m, vertical accuracy: 0.102 ± 0.081 m, point density: ≈40 point/m2). Finally, our other goal is to develop a comparative analysis between light detection and ranging and digital photogrammetry on‐demand. This comparison revealed that flood modelling by photogrammetric DEM was considerably more detailed than that by light detection and ranging‐DEM, mainly because of higher point density and vertical accuracy. Consequently, flood analysis assisted by this novel geometric modelling approach qualifies as a reliable and competitive approach. Copyright © 2016 John Wiley & Sons, Ltd.

Flood Hazard Assessment Supported by Reduced Cost Aerial Precision Photogrammetry

“…ULM and MUSAS ® platforms are widely described in Ortega-Terol et al [66]. Flight parameters and constraints were the same as that in previous research studies in the zone [42,43] because of the optimal ratio (accuracy-spatial resolution) achieved. In addition, it should be noted that meteorological conditions could constraint flight planning.…”

“…This flow value was supplied by the Duero River Basin Authority through a map of instant peak flows in the natural regime [63]. According to previous work in the area Zazo et al [42,43], this flow does not provide relevant consequences neither in the bridge zone nor in the urban area. In contrast, the floodplain is significantly affected because the carrying capacity of the main channel is considerably exceeded.…”

“…Flood modeling involves multiple key aspects including: (i) hydrological model or flood wave characteristics [29], (ii) fluvial geomorphology issues [32][33][34], (iii) the influence of infrastructures such as bridges, dams, or buildings [22,35,36], (iv) structure of hydraulic model, its equations, methods to solve them, and simplifications applied to the model [11,23,37], (v) flow propagation methods [3,38], (vi) human-induced changes in land use [21], (vii) the roughness coefficient [11,31], (viii) vulnerability/damage curves of the potential effects of the flow [22,39,40], and (viii) topographic data of flood prone areas [3,33,[41][42][43].…”

“…This paper forms part of the research line exposed in Zazo et al [42,43] and Zazo [57] that is characterized by hybridizing geomatics and fluvial hydraulics with the purpose of improving the knowledge of flood behavior. In this case, an accurate-high density point cloud was obtained through RC-APP methodology.…”

“…In addition, this work proposes a variant of the non-parametric Robust Estimators (RE) method [42] for assessing the vertical-DTM uncertainty. This provides a dispersion value of error comparable to the concept of standard deviation from a Gaussian distribution without requiring normality tests.…”