Influence of lithology on hydrosedimentological connectivity and aggregate provision in representative sub-basins of the Cuarto/Chocancharava river, Córdoba

Abstract

In order to regulate the extraction of aggregates in the middle reach of Cuarto river (Cba), it is necessary to know the sandy-gravelly sediment replenishment rate, which depends on production and transport of sediment, from the main source areas. Considering that lithology is an important control factor in these processes and taking advantage of the integration potential provided by connectivity studies, in this paper was applied a semi-quantitative index to determine the degree of connection in two smaller basins of different lithology (granitic and metamorphic). The index applied (IC = T + Dd + C - B), which is based on detailed field work, considers storages and linkages between themselves in toposequences (T), drainage density (Dd), number of connections (C) between channels, and barriers (B). This methodology showed satisfactory results according to field observations/monitoring carried out. In the granitic basin of the Arenoso stream, the connectivity was moderately low (IC: 0.35). The sedimentological connections were important (high sediment production and unstable storages), but river transport capacity is limited (ephemeral reaches). In the metamorphic basin of the Moyano stream, the connectivity was low (IC: 0.16). Here there is a limited sediment supply (lower sediment production and high storage stability), although the hydrologic connections are significant (permanent regime). In flood events, the higher Dd, C and lower vegetation cover in the granitic environments, favor the water flow and sediment transport in the drainage network. Therefore, the granitic basins are main repositories of gravelly sands materials towards the middle reach of Cuarto river.