Three-Dimensional Modeling of Wind- and Temperature-Induced Flows in the Icó-Mandantes Bay, Itaparica Reservoir, NE Brazil

Abstract

Abstract:The Icó-Mandantes Bay is one of the major branches of the Itaparica Reservoir (Sub-Middle São Francisco River, Northeast Brazil) and is the focus of this study. Besides the harmful algae blooms (HAB) and a severe prolonged drought, the bay has a strategic importance-e.g., the eastern channel of the newly built water diversion will withdraw water from it (drinking water). This article presents the implementation of a three-dimensional (3D) numerical model-pioneering for the region-using TELEMAC-3D. The aim was to investigate the 3D flows induced by moderate or extreme winds as well as by heating of the water surface. The findings showed that a windstorm increased the flow velocities (at least one order of magnitude, i.e., up to 10 −1 -10 −2 m/s) without altering significantly the circulation patterns; this occurred substantially for the heating scenario, which had, in contrast, a lower effect on velocities. In terms of the bay's management, the main implications are: (1) the withdrawals for drinking water and irrigation agriculture should stop working during windstorms and at least three days afterwards; (2) a heating of the water surface would likely increase the risk of development of HAB in the shallow areas, so that further assessments with a water quality module are needed to support advanced remediation measures; (3) the 3D model proves to be a necessary tool to identify high risk contamination areas e.g., for installation of new aquaculture systems.

Implementation of the AdH hydrodynamic model on the Włocławek Reservoir

“…The unit power of the river stream, determining the transport of river sediments and geomorphological activity, becomes less significant, making way for wave, wind, and density currents, among others. As a result, an internal water circulation system, independent of the river flow, is created in the lower parts of the reservoirs (e.g., Timčenko, 1989;Avakân et al, 1994;Litvinov, 2000;Matta et al, 2017). The importance of the streamflow current, however, is still significant in the backwater part of the reservoirs and, in the case of rheolimnic reservoirs, along their entire length.…”