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Hydrologic Modeling Using Open Source GIS

Hydrologic Modeling Using Open Source GIS. November 13, 2018 GIS Day at UNG Huidae Cho, Ph.D., GISP, PE (MD), CFM Assistant Professor of Geospatial Science and Computing, IESA, UNG Member of the GRASS GIS Development Team. Overview. Hydrologic Modeling Why Open Source? GRASS GIS

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Hydrologic Modeling Using Open Source GIS

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  1. Hydrologic Modeling Using Open Source GIS November 13, 2018 GIS Day at UNG Huidae Cho, Ph.D., GISP, PE (MD), CFM Assistant Professor of Geospatial Science and Computing, IESA, UNG Member of the GRASS GIS Development Team

  2. Overview • Hydrologic Modeling • Why Open Source? • GRASS GIS • TOPMODEL Modeling in GRASS • Optimization of TOPMODEL Hydrologic Modeling Using Open Source GIS

  3. Hydrology Precipitation Infiltration Watershed Streamflow Time Series Evapotranspiration Uptake Return Flow Runoff Streamflow Time Outlet Groundwater Hydrologic Modeling Using Open Source GIS

  4. Purposes of Hydrologic Modeling • Past event simulations • Analysis of evacuation behaviors upon flood disasters • Hypothetical simulations • Drought • Flooding • Impact of urban development on hydrology • Forecasting • Climate change studies Hydrologic Modeling Using Open Source GIS

  5. Hydrologic Model • Hydrologic model: Function of • Known characteristics of the watershed: Area, Stream network, Longest flow path, etc. • Forcing weather data: Observed precipitation, evapotranspiration, wind, radiation, etc. • Model parameters: Conceptualized parameters, Measurable but not measured parameters • Output: Simulated streamflow time series, etc. Hydrologic Modeling Using Open Source GIS

  6. Hydrologic Modeling • Objective: Minimizes the difference between observed and simulated hydrologic variables (e.g., streamflow) • Objective function: A metric that compares observed and simulated variables • Optimization: Minimizes the objective function by calibrating the model parameters Hydrologic Modeling Using Open Source GIS

  7. Source? Open Source? Open Source Source Code = Human-Read-Writable Code Binary Code = Machine Code User Compiler UI Hydrologic Modeling Using Open Source GIS Pictures under Creative Commons Licenses

  8. Why Open Source? Hydrologic Modeling Using Open Source GIS

  9. Open Source GIS • GRASS GIS (Geographic Resources Analysis Support System, http://grass.osgeo.org) • A lot of analysis modules • QGIS (http://qgis.org) • User-friendlierUI • Integrates GRASS GIS modules • MapWindow (http://mapwindow.org) • Windows-nativeUI • Extensible using C# • Windows only • SAGA GIS (System for Automated Geoscientific Analyses, http://saga-gis.org) • gvSIG (http://gvsig.com) • uDig (http://udig.refractions.net) Hydrologic Modeling Using Open Source GIS

  10. GRASS GIS • Official website: http://grass.osgeo.org • First released on July 29, 1983 by the U.S. Army – Construction Engineering Research Laboratory (USA-CERL) • Version 5 released under GNU General Public License (GPL) in 1999 • Contributions from developers and scientists around the world • One of the most scientifically advanced GIS with over 350 modules • Used as a backend GIS engine forweb applications • Extensible and automated through Python or Shell scripting Hydrologic Modeling Using Open Source GIS

  11. TOPMODEL • TOPMODEL (Beven et al. 1995): “a set of conceptual tools that can be used to reproduce the hydrological behaviour” • r.topmodel (Cho 2000): TMOD9502.FOR memory limits removed, translated to C, and integrated into GRASS • Base code for • TOPMODEL package in R • TOPMODEL module in SAGA GIS Hydrologic Modeling Using Open Source GIS

  12. TOPMODEL Hydrologic Modeling DEM Processing Stream Delineation DEM “Burning” DEM Fill sinks Flow direction Flow accumulation Stream delineation TOPMODEL Optimization Topographic index Longest flow path Watershed delineation TOPMODEL TOPMODEL input files Simulated hydrograph Objective function Hydrologic Modeling Using Open Source GIS

  13. Basic Functions Required for Hydrologic Modeling Hydrologic Modeling Using Open Source GIS

  14. Fill Sinks(r.fill.dir) • For hydrologic modeling, no “sinks” are allowed inside the DEM • No watershed delineated • Disconnected streams • All raster cells must flow “out” • Create a hydrologically valid DEM Hydrologic Modeling Using Open Source GIS

  15. “Burning” DEM (r.carve) An embankment crossing the river Hydrologic Modeling Using Open Source GIS

  16. Stream Delineation (r.watershed, r.to.vect) Flow direction Flow accumulation Watersheds Stream vector(r.to.vect) • r.watersheduses theATleast-cost search algorithm  Resistant to DEM noises  Sink filling is not required • r.watersheddrainage  Arc Hydro Flow Direction • r.watershed accumulation  Arc Hydro Flow Accumulation • r.watershed basin  Arc Hydro Batch Watershed Delineation • r.watershed stream  Arc Hydro Stream Definition Stream raster Hydrologic Modeling Using Open Source GIS

  17. Watershed Delineation(r.water.outlet, r.to.vect) • Delineate the watershed draining into the outlet • r.water.outlet Arc Hydro Batch Point Generation & Batch Watershed Delineation r.to.vect Hydrologic Modeling Using Open Source GIS

  18. Longest Flow Path(r.lfp, r.accumulate) • Longest flow path≠Longest stream • Because the stream threshold is always greater than 1 • r.lfp or r.accumulate generates the longest flow path vector Hydrologic Modeling Using Open Source GIS

  19. Topographic Index • Wetness Index • A/tan(b) • A: Upstream area per contour length • b: Local slope • Indicates how much surface runoff each cell can drain downstream Hydrologic Modeling Using Open Source GIS

  20. Isolated-Speciation-based Particle Swarm Optimization (ISPSO) • Cho et al. (2011) • Heuristic algorithm  Derivative-free • Suitable for complex objective functions that are not impossible to derive • Most hydrologic models • Minimizes the objective function using the collective intelligence of particles • Searches the parameter space for solutions • Implemented in R • Applications: Climate change studies, Watershed modeling, Flood modeling, Rainfall modeling, etc. Hydrologic Modeling Using Open Source GIS

  21. How ISPSO Works in a Maximization Problem Objective Function Search Space Hydrologic Modeling Using Open Source GIS

  22. ISPSO: HimmelblauFunction Example +: True solutions, X: Solutions found by ISPSO, o: Particles Hydrologic Modeling Using Open Source GIS

  23. Integration of ISPSO &TOPMODEL GRASS R ISPSO R Script Data Preprocessing GRASS r.topmodel Module Hydrologic Modeling Using Open Source GIS

  24. Optimization of TOPMODEL Using ISPSO • 10 model parameters: 10-dimensional optimization problem • Objective function: Maximizes the Nash-Sutcliffe coefficient(NS) • Uncertainty analysis using a hybrid uncertainty framework, ISPSO-GLUE (Cho and Olivera 2014) Hydrologic Modeling Using Open Source GIS

  25. Future of Open Source GIS • Evolves into specialized platforms • Tethys Platform (http://tethys.ci-water.org ) • Web platform geared towards water resources modeling • Allows to build a web GIS by analyzing and visualizing preprocessed online data • CartoDB (http://cartodb.com) • Web platform that manages and visualizes geospatial data • Baby steps yet in native mobile GIS Full GIS with Much Less Computational Resources? Good old days: GRASS GIS on iPAQ (2004) (http://grass.osgeo.org/screenshots/platforms) QGIS for Android (http://www.opengis.ch/2012/02/10/qgis-on-android-screenshots) Hydrologic Modeling Using Open Source GIS

  26. Future of Open Source GIS (cont.) • Future path for Open Source GIS? • Everywhere • Anytime • Easy • Server & Client Model • Web GIS! • Technologies that will enable WebGIS • Powerful Backend GIS • Cloud Storage • High Speed Mobile Internet • Ever Increasing Power of Mobile CPUs • Distributed Computing & Load Balancing Hydrologic Modeling Using Open Source GIS

  27. Conclusions • Hydrologic modeling is needed for past/hypothetical simulations and forecasting • Free-of-charge or low-cost systems can be built using Open Source • GRASS GIS is one of the most powerful scientific GIS with a lot of analysis modules • GRASS hydrology modules can be a great free substitute for costly Arc Hydro tools • TOPMODEL is an integral part of GRASS • ISPSO can be used to optimize TOPMODEL and perform uncertainty analysis Hydrologic Modeling Using Open Source GIS

  28. References • GRASS GIS: http://grass.osgeo.org • Longest Flow Path: http://idea.isnew.info/grass_gis/how_to_calculate_the_longest_flow_path_in_grass_gis • Topographic Index: http://idea.isnew.info/grass_gis/r.topidx • TOPMODEL: http://idea.isnew.info/grass_gis/r.topmodel • ISPSO: http://idea.isnew.info/research/ispso • Beven, K., Lamb, R., Quinn, P., Romanowicz, R., Freer, J., 1995. TOPMODEL. In: Singh, V.P. (Ed.), Computer Models of Watershed Hydrology. Water Resources Publications, pp. 627-668. • Cho, H., 2000. GIS Hydrological Modeling System by Using Programming Interface of GRASS. Master's Thesis, Department of Civil Engineering, Kyungpook National University, Korea. • Cho, H., Kim, D., Olivera, F., Guikema, S. D., 2011. Enhanced Speciation in Particle Swarm Optimization for Multi-Modal Problems. European Journal of Operational Research 213 (1), 15–23. • Cho, H., Olivera, F., 2014. Application of Multimodal Optimization for Uncertainty Estimation of Computationally Expensive Hydrologic Models. Journal of Water Resources Planning and Management 140 (3), 313-321. Hydrologic Modeling Using Open Source GIS

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