Assessment of a Simplified Connectivity Index and Specific Sediment Potential in River Basins by Means of Geomorphometric Tools

Abstract

Sediment connectivity is a major topic in recent research because of its relevance in the characterization of the morphology of river systems and assessing of sediment transport and deposition. Currently, the connectivity indices found in the literature are generally dimensionless and need to be coupled with quantitative soil-loss data for land management and design purposes. In the present work, a simple methodology is proposed to assess two different indices, namely, the simplified connectivity index (SCI) and the specific sediment potential (SSP), based on geomorphometric tools that are commonly available in commercial and open-source geographic information system (GIS) platforms. The proposed metrics allows us to easily assess both the SCI and the SSP as functions of the estimated soil erosion per unit area of the catchment and of the inverse distance of each unit area from the river outlet, this distance being measured along the network path. The proposed indices have been devised to express, respectively, the potential sediment transfer ability and the sediment mass potentially available at a given section of the drainage network. In addition to other parameters used to describe the catchment characteristics potentially affecting the river sediment delivery capacity, the SCI and SSP indices can help to refine theoretical models in order to assess the sediment yield (SY) in ungauged river basins.

To What Extent Can a Sediment Yield Model Be Trusted? A Case Study from the Passaúna Catchment, Brazil

“…Hydrological connectivity is a term often used to describe the linkages between runoff and sediment generation in the upper parts of catchments and the receiving waters [44]. The use of the connectivity index as an input parameter for SDR has shown satisfying results globally [45][46][47][48]. For this study, the calculation of the connectivity index, and subsequently SDR, was implemented in ArcMap 10.5 as described in [49] based on the following formula:…”

Geomorphic connectivity and its application for understanding landscape complexities: a focus on the hydro‐geomorphic systems of India

“…Sediment connectivity in river basins has attracted a lot of attention in recent years (Fryirs et al ., 2007a; Cavalli et al ., 2013; Fryirs, 2013; Fryirs and Gore, 2013; Foerster et al ., 2014; Bracken et al ., 2015; Grauso et al ., 2018; Heckmann et al ., 2018) and most studies have focused on understanding the potential of sediment transfer from source to sink in small river catchments. In one of the very few studies on large river basins, the upper Kosi basin in Tibet and Nepal, remarkable spatial variability in sediment connectivity has been demonstrated (Mishra et al ., 2019) which has been discussed in the previous section.…”

Computing structural and functional flow and sediment connectivity with a new aggregated index: A case study in a large Mediterranean catchment

“…Recent studies have reported the necessity of developing accurate modelling tools for geomorphic investigation of sediment pathways, cross-scale connectivity processes and how overland flow inputs change from various sources, but keeping simplified mathematical and computational methodologies (Williams et al, 2016;Cossart and Fressard, 2017;Grauso et al, 2018). The new approach presented in this study to compute FSC kept the simple mathematical structure of the well known Borselli's index of FSC and increased the number of inputs at the same time.…”