During the developmente of the project we have collected, homogenized and analyzed long-term (over 15 years) sediment transport records of four middle mountain experimental catchment managed by the IPE with a gradient of land cover modification: San Salvador (forest river basin), Arnás (abandoned field experimental catchment with progressive plant recolonization), Repoblación (afforested experimental catchment) and Araguás (badland experimental catchment). These four experimental catchments are located in the Spanish Pyrenees. They are completely equipped and they have cumulated data of sediment transport and channel morphology of over two decades. All four experimental catchments have rainfall driven flood hydrology. Current and past information on the sedimentary data (amount, type, timing of sediment inputs) have been analyzed to assess long-term trends and cycles between land cover and sediment regimen data.
We have used the method of wavelet transformation to identify the time-scale dependency of suspended sediment patterns concerning the temporally and spatially uneven transient processes of sediment production, accumulation, and transport. We have analyzed the temporal variation of concurrent discharge and suspended sediment fluxes in order to bridge the limitations of pure predictive models to learn from temporal data structures with the main purpose of identifying the mechanisms underpinning the suspended sediment patterns (e.g. climatic forces). Intraseasonal-to-seasonal, annual, and inter-annual dominant time-scales are thus identified. The short time-scales are driven by the quad-modal seasonal precipitation pattern specific to the climate of the region and provide a continuous supply of sediments to the river. The large time-scales, controlled by high magnitude flow events and within-reach sediment storage, display alternating periods of increasing and decreasing sediment fluxes; ultimately, they maintain the river channel within balance or within a moderate positive sediment accumulation process. This analysis and methodology help to understand temporal sediment dynamics, and ultimately to manage river catchments.
