Morphological characterization using South Rivers Toolbox in the Duqueco river: A support tool for river management

Abstract

<p>The phenomena associated with global climate variability may lead to more intense extreme events, thus causing an increase in floods and prolonged droughts. In view of this situation, the Chilean Directorate of Hydraulic Works (DOH) has the task of selecting the works to be executed with the highest priority with the annual budget, to control and mitigate the effects of floods. Hence the need for a tool that includes the evaluation of fluvial morphodynamics, which allows the management of hydraulic works compatible with the processes of response and adjustment of the channels. The objective of this study is to characterize the fluvial styles of the Duqueco River based on its geomorphology, to understand the character and behavior of the fluvial corridor in a semi-automatic way applying GIS techniques and Python geoprocessing. The first stage of the River Styles framework is applied through the South Rivers Toolbox program, which characterizes and classifies fluvial styles based on hydromorphological attributes measured at segment scale, implementing a semi-automatic approach that reduces expert judgment. Previously, the disaggregation and aggregation framework is used, which determines channel attributes at a local scale, and then aggregates them with a statistical test in larger reaches. The whole process is performed in a semi-automated way with tools from the South Rivers Toolbox set within the QGIS software. As results, 36 main fluvial styles and 47 complementary styles are classified and characterized, and the river channel is analyzed in 3 zones. The upper zone is characterized by being mostly confined, mono-channel, with a bed of boulders and blocks, being highly intervened by power generation works; the middle zone is still mostly confined and mono-channel, with a change in the type of bed towards boulders. Finally, the lower zone is more diverse in styles, mostly unconfined, with a high presence of geomorphic units that give way to multichannel and transition zones.</p>

Automatic River Planform Recognition Tested on Chilean Rivers

“…Although the Planform and Holistic Tools were developed on an Excel ® platform, the whole package was conceived to be potentially fully automatized once the basic geomorphic elements and units are provided (a task that itself can potentially be conducted in an automatized way similar to, for instance, that used in [8,19,28]). However, difficulties are present, like the ability to determine for each discretization slice the length of the water channels intercepted or the initial estimation of the sinuosity (which itself requires an iterative procedure).…”

“…Additionally, we utilized the South Rivers Toolbox tool within the QGIS 3.x interface [28] to enhance our analysis. We employed the segmentation tool offered by the "River Skeleton" module to segment the active channel and its envelope.…”

“…With a hydrographic basin of 1550.8 km 2 and an approximate length of 102 km (evaluated in this study), the Duqueco River has a remarkable size. Its tributaries are the Canicura, Quillaco, and Llerquenco streams, with the Coreo River as its main tributary [28]. Table 1 reports additional data on the morphometric characteristics of these rivers.…”

Linking the Evolution of the Andalién River Morphology (Central–Southern Chile) to Anthropogenic Interventions by Using a New QGIS Tool

“…This consists of extracting the geomorphological characteristics of a watershed by first disaggregating Unit Geographic Objects (UGO) (the valley bottom, the active channel, its envelope, and their axis, as well as the geomorphic units) obtained from temporal satellite images and DEM and then aggregating the obtained data (DGO: Disaggregated Geographical Objects) according to other criteria, particularly for each river reach, thereby obtaining new Aggregated Geographic Objects (AGUs; for instance, a reach with a uniform width). The Centerline for Active Channel and Valley Bottom (Floodplain) was obtained following the methodology explained by [14].…”

“…Comprehensive assessment of river morphological change analysis based on local surveys is, however, costly, and time-consuming; in this sense, advanced techniques, like remote sensing, offer an efficient support for this task. Nardini et al [13] and Yépez et al [14] recently developed a semi-automated framework and process to conduct a River Styles analysis, systematizing the role of subjective expert judgments. This process is highly supported by a new plugin being developed in QGIS called as South Rivers Toolbox (SRT).…”