@article{PB-VRVis-2019-009, author = {Buttinger-Kreuzhuber, Andreas and Horvath, Zsolt and Noelle, Sebastian and Bl{\"o}schl, G{\"u}nter and Waser, J{\"u}rgen}, title = {A fast second-order shallow water scheme on two-dimensional structured grids over abrupt topography}, year = {2019}, journaltitle = {Advances in Water Resources}, doi = {10.1016/j.advwatres.2019.03.010}, url = {https://www.vrvis.at/publications/PB-VRVis-2019-009}, issn = {0309-1708}, pages = {89 - 108}, volume = {127}, abstract = {This paper presents a finite volume scheme on structured grids to simulate shallow flows over complex terrain. The situation of shallow downhill flow over a step is particularly challenging for most shallow water schemes. We study this situation in detail and devise a novel second-order reconstruction strategy, which gives superior results over former hydrostatic reconstruction (HR) schemes. The reconstruction step is based on a recent first-order hydrostatic reconstruction HR method, which improves shallow flows over steps. The proposed second-order scheme is well-balanced, positivity-preserving, and handles dry cells. When compared with the original HR, we lower the computational burden by using a simplified quadrature for the bed slope source term. We test the scheme on various benchmark setups to assess accuracy and robustness, where the method produces comparable results to other HR-based schemes in most cases and superior results in the case of shallow downhill flow over steps. The novel second-order scheme is capable of simulating large-scale real-world flood scenarios fast and accurately.}, keywords = {Shallow water, Saint-Venant, Slope source term, Well-balanced scheme, Second-order reconstruction}, }