Multitemporal assessment of coarse sediment connectivity along a braided‐wandering river

Abstract

AbstractThe article presents the postflood period coarse sediment connectivity (CSC) assessment approach on the basis of the holistic ideas of the interpretation of the long‐term CSC in river channels. Seven sets of remote sensing data (1949–2009) were used as the basic information sources to study the CSC along the braided‐wandering Belá River by using the patch‐graph approach for assessing the structural connectivity. The bar areas (patches), with 200 m direct links between them, and the attribute of a deflection angle of a link to the flow direction were parameters used to estimate the integral index of connectivity (IIC) and bar area and bar link importance indices. The higher values of the IIC fit with a well‐developed bar system. Conversely, the values of the IIC decrease because of the progressive degradation of the braided pattern. The potential functional CSC was inferred from the variability of the values obtained by the balance indices representing the balance of the channel–floodplain connectivity (B1) and the bar–bar connectivity (B2). Eight types of the potential functional CSC based on the balance indices and the deduction of processes that conditioned the channel–floodplain and in‐channel CSC linkages were identified. In order to assess the development of the braidplain pattern in terms of the structural connectivity during the study time span, the linear trendline analysis of IIC associated with flood periods was applied. On the basis of the coefficient of determination, all reaches exhibit a decreasing trend in IIC values but different response to flood periods.