Geomorphospace

A theoretical morphospace for river deltas — every delta that has ever existed, and every delta that could.

🌊 Live at noahkarsky.github.io/geomorphospace

An interactive, single-file visualization inspired by Raup's (1966) shell-coiling morphospace and built on Galloway's (1975) river–wave–tide ternary classification, quantified with the sediment-flux framework of Nienhuis et al. (2020, Nature).

Drag through the ternary diagram — or tune the river / wave / tide energy balance and sediment calibre — and a synthetic delta planform is drawn procedurally, morphing between birdsfoot, cuspate, and funnel-shaped forms. A catalog of 50 real deltas is plotted in the space; click any of them to load it into the instrument.

Running it locally

It's one dependency-free index.html. Open it in a browser, or serve the folder with any static server.

Data honesty

The three fractions per delta are relative sediment-flux dominance (fR + fW + fT = 1). Eight entries carry values quoted directly from Paniagua-Arroyave & Nienhuis (2024); the rest are literature-consistent placements (Galloway 1975; Orton & Reading 1993; Bhattacharya 2006) and are flagged estimated in the source. The synthetic planform is a cartoon with a physics accent — an educational visualization, not a morphodynamic simulation.

References

• Galloway, W.E. (1975). Process framework for describing the morphologic and stratigraphic evolution of deltaic depositional systems. In Deltas: Models for Exploration, Houston Geological Society, 87–98.
• Nienhuis, J.H., et al. (2020). Global-scale human impact on delta morphology has led to net land area gain. Nature, 577, 514–518.
• Paniagua-Arroyave, J.F. & Nienhuis, J.H. (2024). The quantified Galloway ternary diagram of delta morphology. JGR: Earth Surface, 129, e2024JF007878.
• Raup, D.M. (1966). Geometric analysis of shell coiling: general problems. Journal of Paleontology, 40(5), 1178–1190.
• Orton, G.J. & Reading, H.G. (1993). Variability of deltaic processes in terms of sediment supply. Sedimentology, 40, 475–512.
• Wright, L.D. & Coleman, J.M. (1973). Variations in morphology of major river deltas. AAPG Bulletin, 57(2), 370–398.
• Syvitski, J.P.M. & Saito, Y. (2007). Morphodynamics of deltas under the influence of humans. Global and Planetary Change, 57, 261–282.

Born as a hypnagogic idea in a junior-year stratigraphy class.