Tectonic and geomorphic processes drive landscape evolution over different spatial and temporal scales. In mountainous environments, river incision sets the pace of landscape evolution, and hillslopes respond to channel incision by e.g. gully retreat, bank erosion and landslides. Sediment produced during stochastic landslide events leads to mobilisation of soil and regolith on the slopes that can later be transported by gravity and water to the river network. Quantifying sediment storage and conveyance requires an integrated approach accounting for different space and time scales. To better understand mechanisms and spatial and temporal scales of geomorphic connectivity in mountainous environments, we characterised the sediment cascade of the Entle River catchment located in the foothills of the Central Swiss Alps. We quantified sediment fluxes over annual, decadal and millennial time scales using respectively UAV-SfM techniques, classic photogrammetry and in situ produced cosmogenic radionuclides. At the annual scale (2013–2015), the sediment budget of the Schimbrig earthflow is roughly in equilibrium, despite the fact that we measured intense sediment redistribution on the hillslopes. At the decadal scale (1962–1998), Schwab et al. (2008) reported episodes of sediment export that were not directly related to increased geomorphic activity on the hillslopes. At the millennial scale, catchment-wide denudation rates show a positive relationship with downstream distance or drainage area, when ignoring landslide-affected catchments. The latter are characterised by a negative relationship between denudation rates and downstream distance, along with high variability in denudation rates. The high denudation rates that we measured in the earthflow-affected Schimbrig catchment are illustrative for its high rates of geomorphic activity in comparison to adjacent areas. Our data show that the elevated denudation rates of the landslide-affected catchments are not necessary traceable when analyzing long-term sediment fluxes of the wider geographic area, as the landslide-affected catchments are often only a small fraction of the total catchment. The multi-temporal assessment of sediment fluxes indicates that (1) landslides can provide local sediment pulses, and mobilise material that becomes available for further mobilisation and transport when hillslopes and channels are connected. (2) Connection and disconnection cycles occur at decadal time scale. (3) Phases of high geomorphic activity at the catchment scale are episodic over thousands of years. Consequently, one single landslide has not necessarily an impact on the long-term sediment budget of first-order catchments. Rather, it is the cumulated effect of multiple landslides which are intermittently connected to the channel network at the decadal scale that may regulate sediment fluxes at the regional scale over the millennial time scale.