- 1Department of Earth Science and Engineering, Imperial College London, London, UK (jonah.mcleod18@imperial.ac.uk)
- 2Grantham Institute, Science and Solutions for a Changing Planet DTP, London, UK
- 3Department of Geography, University of California Santa Barbara, Santa Barbara, USA
- 4School of Geography and the Environment, University of Oxford, Oxford, UK
We present the largest river intermittency dataset to-date, and the first to document both water and sediment transport intermittency globally. River intermittency describes the ratio between long-term average and instantaneous maximum transport rates of water or sediment (Paola et al., 1992). It is an important way of quantifying the distribution of river activity through time, and is especially useful when interpreting the frequency of threshold-surpassing events in the geologic past. Patterns of sediment flux are key to understanding transient landscape response to external drivers such as climate change in the past or future. But sediment intermittency is much more challenging to estimate than water intermittency, and interpretations of stratigraphy are limited without absolute constraints on modern-day intermittency.
Using a range of inputs from published datasets and empirical-theoretical transport models, we calculated and compiled water and sediment transport intermittency factors for over 300 river reaches worldwide. This new dataset spans 6 continents and all climate zones except polar, and describes discharge rates, catchment and bed characteristics, and planform morphology, among other geomorphic variables. We find that sediment transport intermittency factor (Is) is significantly more variable than water discharge intermittency factor (Iw) worldwide. Both Is and Iw behave as a predictable function of climate zone, with rivers in arid and cold climates more intermittent (lower Is and Iw) than those in tropical and temperate climates. However, river planform dominates the control on sediment intermittency. Braided rivers are on average 100x more intermittent than meandering rivers: with increasing channel count, Is values become consistently lower. This raises important questions about the connections between fluvial morphology, climate and the rates and patterns of transport, and demonstrates the extent to which river planform is intrinsically linked to geomorphic response to environmental change.
How to cite: McLeod, J., Ganti, V., Whittaker, A., Bell, B., Hampson, G., Slater, L., and Liu, Y.: Intermittent World: A Global Analysis of River Water and Sediment Intermittency , EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-10386, https://doi.org/10.5194/egusphere-egu25-10386, 2025.
