Controls on River Avulsion Style

in Foreland Basins

Modern Avulsion Events Are Captured in Landsat Imagery

  • Avulsion Events Throughout Andean, Himalayan, and New Guinean Foreland Basins

  • Features of Avulsion Events Are Resolvable in Time and Space

    After identifying avulsion events well-documented in the Landsat archive, we can observe channel and floodplain disturbances in bands of visible light, suggesting that further visualization may result from taking all bands into account.

Applying a median reducer removes noise and seasonal variation

 

 Compressing Landsat spectral bands yields new physically meaningful bands

(Detailed description coming soon!)

Empirically derived thresholds of brightness, greenness, and wetness values accurately identify avulsion pixels

Compiling all years produces a final avulsion “fingerprint”, which can be validated with high-resolution imagery

 

 We develop a quantitative measure of avulsion style by comparing the area of the avulsion fingerprint to the area of the parent channel

Avulsion style ratios relate to distance, slope, and channel morphology

  • (Detailed description coming soon!)

Avulsion style ratio increases downstream, on lower slopes, and in single-thread channels

 

Detailed discussion published in the following articles:

Valenza, J.M., Edmonds, D.A., Hwang, T.H., Roy, S., (2020) Downstream changes in river avulsion style are related to channel morphology, Nature Communications, v. 11, is. 1, p. 1-8.

Edmonds, D.A., Martin, H.K., Valenza, J.M., Henson, R., Weissmann, G.S., Miltenberger, K., Mans, W., Moore, J.R., Slingerland, R.L., Gibling, M.R., Bryk, A.B., Hajek, E.A., (2022) Rivers in reverse: Upstream-migrating dechannelization and flooding cause avulsions on fluvial fans, Geology, v. 50, is. 1, p. 37-41.

Valenza, J.M., Edmonds, D.A., Weissmann, G.S., (2022) Quantifying river avulsion activity from satellite remote sensing: Implications for how avulsions contribute to floodplain stratigraphy in foreland basins, Journal of Sedimentary Research, v. 92, is. 6, p. 487-502.

Valenza, J.M., Edmonds, D.A., Toby, S., Sifuentes, C., (in prep) Avulsion signatures within the Salt Wash Member of the Morrison Formation, in prep for Sedimentology.