Monitoring of riparian vegetation response to flood disturbances using terrestrial photography

Abstract

The distribution of riparian vegetation on river floodplains is strongly impacted by floods. In this study we use a new setup with high resolution ground-based cameras in an Alpine gravel bed braided river to quantify the immediate response of riparian vegetation to flood disturbance with the use of vegetation indices. Five largest floods 5 with return periods between 1.4 and 20.1 years in the period 2008-2011 in the Maggia River were used to evaluate patterns of vegetation response in three distinct floodplain units (main bar, secondary bar, transitional zone) and to compare seven vegetation indices. The results show both negative (damage) and positive (enhancement) response of vegetation in a short period following floods, with a selective impact based on the 10 hydrogeomorphological setting and the intensity of the flood forcing. The spatial distribution of vegetation damage provides a coherent picture of floodplain response in the three floodplain units with different flood stress. We show that the tested vegetation indices generally agree on the direction of predicted change and its spatial distribution. The average disagreement between indices was in the range 14.4-24.9 % despite the 15 complex environment, i.e. highly variable surface wetness, high gravel reflectance, extensive water-soil-vegetation contact zones. We conclude that immediate vegetation response to flood disturbance may be effectively monitored by terrestrial photography with potential for long-term assessment in river management and restoration projects.is largely determined by floodplain morphology and the hydrological regime of the river 3360

Optimizing the Timing of Unmanned Aerial Vehicle Image Acquisition for Applied Mapping of Woody Vegetation Species Using Feature Selection

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