Simulation of Density-Driven Flow Using a Two-Dimensional Surface Water Model

Water Qualit

Shallow water equations with depth-dependent anisotropic porosity for subgrid-scale topography

This paper derives a novel formulation of the depth-averaged shallow water equations with anisotropic porosity for computational efficiency reasons. The aim is to run simulations on coarser grids while maintaining an acceptable accuracy through the introduction of porosity terms, which account for subgrid-scale effects. The porosity is divided into volumetric and areal porosities, which are assigned to the cell volume and the cell edges, respectively. The former represents the volume in the cell available to flow and the latter represents the area available to flow over an edge, hence introducing anisotropy. The porosity terms are variable in time in dependence of the water elevation in the cell and the cumulative distribution function of the unresolved bottom elevation. The main novelty of the equations is the formulation of the porosities which enables full inundation of the cell. The applicability of the equations is verified in five computational examples, dealing with dam break and rainfall-runoff simulations. Overall, good agreement between the model results and a high-resolution reference simulation has been achieved. The computational time decreased significantly: on average three orders of magnitude

Modeling Shallow Water Flow And Transport Processes With Small Water Depths Using The Hydroinformatics Modelling System

In hydro- and environmental systems modelling, there are several application cases where very small water depths occur, for example rainfall and runoff in natural or urban catchments, possibly associated with tracer transport. In these cases, the water depth may be in the range of millimeters to a few centimeters. The numerical simulation of the associated processes is complex, therefore robust numerical schemes are required. Two test cases using high resolution topography data are investigated with the Hydroinformatics Modelling System (HMS). In the first case, the influence of microtopography and local depressions were analyzed in an idealized urban catchment; both had a strong impact on the hydrograph. In the second one, rainfall runoff experiments, which were carried out by Mügler et al. [10] were simulated. Through parameter optimization an overall good agreement between computed and measured breakthrough curves was achieved

Isotope hydrology and water sources in a heavily urbanized stream

Funding Information: We thank D. Dubbert and A. Dahlmann for running the isotopic analysis in the isotope laboratory of IGB. A. Smith is thanked for advice on aspects of the analysis and comments on an earlier draft. Additionally, we thank the Berliner Wasserbetriebe (BWB), and Berlin Senate for constructive information, expert knowledge, feedback and provision of data, as well as access to their groundwater wells. L. Kuhlemann and L. Kleine are thanked for constructive feedback and discussion. Funding from this study was through the project “Modelling surface and groundwater with isotopes in urban catchments” (MOSAIC) provided by the Einstein Foundation and CM is associated with the Research Training Group “Urban Water Interfaces” (UWI), GRK 2032/2 as a collegiate, financed by the German Research Foundation (DFG). Contributions from CS were also funded by the Leverhulme Trust's ISOLAND project. We also thank three anonymous reviewers for their constructive reviews.Peer reviewedPublisher PD

Three-dimensional modeling of wind- and temperature-induced flows in the Icó-Mandantes Bay, Itaparica Reservoir, NE Brazil

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.DFG, 325093850, Open Access Publizieren 2017 - 2018 / Technische Universität Berli

An efficient unstructured MUSCL scheme for solving the 2D shallow water equations

The aim of this paper is to present a novel monotone upstream scheme for conservation law (MUSCL) on unstructured grids. The novel edge-based MUSCL scheme is devised to construct the required values at the midpoint of cell edges in a more straightforward and effective way compared to other conventional approaches, by making better use of the geometrical property of the triangular grids. The scheme is incorporated into a two-dimensional (2D) cell-centered Godunov-type finite volume model as proposed in Hou et al. (2013a,c) to solve the shallow water equations (SWEs). The MUSCL scheme renders the model to preserve the well-balanced property and achieve high accuracy and efficiency for shallow flow simulations over uneven terrains. Furthermore, the scheme is directly applicable to all triangular grids. Application to several numerical experiments verifies the efficiency and robustness of the current new MUSCL scheme

A Novel Slope Failure Operator for a Non-Equilibrium Sediment Transport Model

Complex transport mechanism and interaction between fluid and sediment make the mathematical and numerical modeling of sediment transport very challenging. Different types of models can lead to different results. This paper investigates a non-equilibrium sediment transport model based on the total load. In this type of model, it is assumed that a bed slide will occur if the bed slope reaches a critical angle. This is enabled by means of a slope failure operator. Existing slope failure operators usually suffer from the high computational cost and may fail at wet/dry interfaces. The main contribution of this work is the development of a novel slope failure operator for the total load transport model, based on a modified mass balance approach. The proposed approach is verified in three test cases, involving bank failure, dyke overtopping and a two-dimensional bank failure. It is shown that the proposed approach yields good agreement with analytical results and measurement data

High Resolution Simulation of Surface Water Flow in Natural Catchment Areas

Source: ICHE Conference Archive - https://mdi-de.baw.de/icheArchiv

High-resolution Numerical Analysis of Flow over a Ground Sill Using OpenFOAM

Source: ICHE Conference Archive - https://mdi-de.baw.de/icheArchive