Simple scaling analysis of active channel patterns in Fiumara environment

• Simple scaling analysis of active channel patterns of Fiumara river systems.
• Probabilistic description of active channel by truncated Poisson distribution.
• Bimodal scaling behaviour of active channel patterns.
• Scale and fractal parameters characterizing the number of active channels.

A simple scaling analysis was performed on experimental data relative to a riverbed reach of the Allaro Fiumara, a fluvial environment typical of Southern Italy. For this purpose, a simplified geometrical approach was followed to determine the spatial distribution of the number of active channels for the river stretch considered. In particular, the section lines crossing the braided network skeleton with distance ranging from 5 to 200 m were considered. Firstly, a probabilistic analysis of the experimental data was carried out by using a truncated Poisson distribution to characterize the examined river morphologically. Afterward, a scaling analysis was performed to investigate the existence of a possible multimodal behaviour of the number of active channels and to identify the corresponding cutoff values. For this second approach by the so-called standard coarse graining analysis, we defined a power law usable to give the probability distribution of the active channels number with varying spatial partition (distance between consecutive sections). In this way, verifying the existence of a bimodal scaling behaviour was possible. Moreover, the cutoff limits that characterize the bimodal behaviour of the active channels were found for all the partition distances from 5 to 100 m, while the corresponding shape and scale parameters were also determined. A comparison of the results obtained by the statistical approach and the scaling analysis was carried out. The variability of the characteristic parameters of the Poisson and power type laws with scale was also investigated.