Quantifying High-Frequency Lacustrine Sedimentation Patterns using Publicly Available Data

Abstract:

The primary hypothesis motivating this work is that lacustrine delta progradation is highly coupled to lake level rise from increased riverine discharge at multiple scales of cyclicity. This is fundamentally opposite to the well-described relationship between delta progradation and sea level fall, questioning the applicability of marine depositional models to lacustrine settings.

Lacustrine environments are excellent candidates for remote study due to their relatively small spatial extents, seasonal water level fluctuations, quantifiable inflow (discharge, precipitation, etc.), and the nature of the shoreline as system boundary relating external and internal processes that control lacustrine equilibrium (Gilbert, 1978). The closed, continuous nature of lake shorelines creates predictable responses to external forcing: either basin-ward movement (indicating local deposition) or land-ward (indicating erosion).

Using static images of a lake (from LANDSAT, Sentinel-2) with associated time-equivalent lake water level information allows for comparison between multiple temporally disparate but altitudinally similar shoreline contours, eliminating the possibility of vertical water column movement laterally changing shoreline position irrespective of sedimentation or erosion. Differences between two shoreline contours can be computed as areas of deposition/erosion.

A time-series can be generated of periods of net deposition and erosion, giving insight to the periodicity and magnitude of lacustrine sedimentary regimes. Preliminary results show a deltaic progradational signal (net deposition) during overall lake level rise in Lake Ayakuum, China.