Identification of Knickpoints in Littoral Basins of Argentine Patagonia: Geomorphic Markers in a Passive Margin

BORETTO, G.; GARCÍA ARAOZ, E.; CIOCCALE, M.; GORDILLO, S.; TELLO, J.

Advances in Geomorphology and Quaternary Studies in Argentina

SPRINGER

Año: 2019; p. 182 - 208

Knickpoints are an expression of disequilibrium in a fluvial systemand they occur in both alluvial and bedrock rivers. A significant amount ofresearch in the past decade around the globe demonstrated the usefulness of theknickpoints as geomorphic markers, specially in active margins, which due to itsformation is related to tectonic, climatic and geomorphic processes. However,less attention is paid to the fluvial systems in well-developed along the passivecoastal margin as the Atlantic Ocean coast in Patagonia. For the first time in thisregion, knickpoint analysis together with hypsometric curves and longitudinalstream profiles studies were conducted to understand the landform evolution incoastal basins along the passive margin in Bustamante and Solano Bays (Chubutprovince, Patagonia, Argentina) during the recent past. The methodologyemployed digital elevation models (DEMs) and satellite images which havebeen processed by ArcGIS software using such specific tools as (1) ArcHydroand knickpointfinder, (2) CalHypso, and (3) TopoToolbox (which contains a setof MATLAB functions) to complete the proposed studies. A total of 590knickpoints were identified along longitudinal fluvial profiles in 18 basins. Theresults suggest that knickpoints frequency and density vary according to thelithological-structural and tectonic conditions, and it is possible to separate twosectors in the study area, in both the northern and the southern portion, being thesouthern zone more dynamic linked to active alignments in the depocenter of theSan Jorge Gulf. This work provides a method for using knickpoints as geomorphicmarkers in coastal basins associated to the Atlantic Ocean coast.