5:15 PM - 7:15 PM
[SVC31-P10] On the shape of flow network by using flow routing algorithms applied to the smooth slopes generated by pyroclastic deposits
Keywords:flow network, pyroclastic deposit slope, volcano, Sarakujima
After a volcanic eruption, the pyroclastic deposits covering over fine-scale landforms make the slopes smooth. As estimating the occurrence of mudflow by numerical simulation, it is necessary to model such landforms to be appropriate. So as doing generally, hydrologic functions in a geographic information system (GIS) are used. One of basic methods for this function is the flow routing algorithm.
A representative flow routing algorithm, D8 method, is mostly used in a standard GIS. Input data of D8 methods is numerical elevation model (DEM) where elevation values are given in a space-divided grid. However, on smooth slopes such as those described above, the flow path direction is not simply determined in the 8 directions which are assumed by D8 method. Thus it has been pointed out that the generation of flow paths by D8 were not adequate for natural shape of flow networks and for slope gradients (e.g., [1], [2]).
To solve these problems, various flow routing algorithms are proposed, which broadly classified into Single Flow Direction methods (including D8) and Multiple Flow Direction methods. Comparisons among methods have been performed for simple geometries that can be mathematically evaluated for its error [2], [3].
Therefore, we applied the various methods of flow routing algorithms proposed so far to the DEM of the ash accumulation slope of Sakurajima, which is smooth around the crater, and calculated the Total Catchment Area or Total Contributing Area, and check the shape of flow networks.
We would like to express our gratitude to my boss Motoki Ito for useful advice, the Osumi Office of Rivers and National Highways, Kyushu Regional Development Bureau, Ministry of Land, Infrastructure, Transport and Tourism (MLIT) for using Aerial LiDAR data and the authors of [2] [4] for opening the code of flow routing algorithms.
References
[1] Orlandini, S., and G. Moretti (2009), Determination of surface flow paths from gridded elevation data, Water Resources Research, 45, W03417, doi:10.1029/2008WR007099
[2] Wu, P., Liu, J., Han, X., Feng, M., Fei, J., and Shen, X. (2022). An improved triangular form-based multiple flow direction algorithm for determining the nonuniform flow domain over grid networks. Water Resources Research, 58, e2021WR031706. doi:10.1029/2021WR031706
[3] Zhou, Q., and Liu, X., (2002) Error assessment of grid-based flow routing algorithms used in hydrological models, Int. J. geographical information science, 16-8, 819-842, doi:10.1080/13658810210149425
[4] Lindsay, J., B. (2016) Whitebox GAT: A case study in geomorphometric analysis, Computers & Geosciences, 95, 75-84, http://dx.doi.org/10.1016/j.cageo.2016.07.003
A representative flow routing algorithm, D8 method, is mostly used in a standard GIS. Input data of D8 methods is numerical elevation model (DEM) where elevation values are given in a space-divided grid. However, on smooth slopes such as those described above, the flow path direction is not simply determined in the 8 directions which are assumed by D8 method. Thus it has been pointed out that the generation of flow paths by D8 were not adequate for natural shape of flow networks and for slope gradients (e.g., [1], [2]).
To solve these problems, various flow routing algorithms are proposed, which broadly classified into Single Flow Direction methods (including D8) and Multiple Flow Direction methods. Comparisons among methods have been performed for simple geometries that can be mathematically evaluated for its error [2], [3].
Therefore, we applied the various methods of flow routing algorithms proposed so far to the DEM of the ash accumulation slope of Sakurajima, which is smooth around the crater, and calculated the Total Catchment Area or Total Contributing Area, and check the shape of flow networks.
We would like to express our gratitude to my boss Motoki Ito for useful advice, the Osumi Office of Rivers and National Highways, Kyushu Regional Development Bureau, Ministry of Land, Infrastructure, Transport and Tourism (MLIT) for using Aerial LiDAR data and the authors of [2] [4] for opening the code of flow routing algorithms.
References
[1] Orlandini, S., and G. Moretti (2009), Determination of surface flow paths from gridded elevation data, Water Resources Research, 45, W03417, doi:10.1029/2008WR007099
[2] Wu, P., Liu, J., Han, X., Feng, M., Fei, J., and Shen, X. (2022). An improved triangular form-based multiple flow direction algorithm for determining the nonuniform flow domain over grid networks. Water Resources Research, 58, e2021WR031706. doi:10.1029/2021WR031706
[3] Zhou, Q., and Liu, X., (2002) Error assessment of grid-based flow routing algorithms used in hydrological models, Int. J. geographical information science, 16-8, 819-842, doi:10.1080/13658810210149425
[4] Lindsay, J., B. (2016) Whitebox GAT: A case study in geomorphometric analysis, Computers & Geosciences, 95, 75-84, http://dx.doi.org/10.1016/j.cageo.2016.07.003