Muhamad Uznir Ujang

3D Volumetric Soft Geo-objects for Dynamic Urban Runoff Modeling

Complexities of streamflow structures, drainage systems, sewers and urban landscape render difficulties for urban flood mitigation and rehabilitation planning towards reducing urban flood disaster. GIS has been useful for the investigation of urban runoff spatial patterns. However, the inability of GIS to realistically explore the momentum and continuity aspects of overland flow and urban runoff process has been proven to be the shortcomings of the system. This leads to the requirement of an extended dimension representing dynamic soft geometrical volumes of urban stormwater runoff. The inclusion of Volumetric Soft Geo-objects (VSG) offers a comprehensive and practical 3D dynamic modeling of urban runoff volume. The VSG are driven based on Kinematic Wave Routing and Green-Ampt method for modeling open channel flow and overland flow volume respectively. Basin model, sub-basin, reach and junction elements are extracted from Digital Elevation Model (DEM) with 5 meter resolution using the HEC-GeoHMS program and the HEC-HMS model. The modeled results of discharge volume gave an R2 of 0.88 and a Nash–Sutcliffe coefficient of 0.82, indicating that VSG provides end-users the prospect to envision complex information of flood disaster management.

3D Dynamic Simulation and Visualization for GIS-based Infiltration Excess Overland Flow Modelling

Effective GIS-based Infiltration Excess Overland Flow (IEOF) simulation and visualization requires good knowledge of GIS core concepts and prediction of soil infiltration rates due to impervious area coverage. The success or failure of GIS-based IEOF simulation and visualization resides initially with the georeference system used. Cartographers have long complained about the poor quality of the output from GIS, which today is generally due not to limitations of the GIS itself but instead to a lack of understanding of cartographic principles among hydrologists and environmentalists. Implementation of soft geo-objects representing flow elements such as streams, mudflows, and runoff provides better dynamic visualization in terms of velocity and direction. Inclusion of volumetric overland flow would help in determining the volume of runoff that hits the flood-plain areas, estimating channel flow capacity, and routing and diversions to reduce effects from flooding. With rapid urbanization, industrialization, and climate change, historical runoff and infiltration rates would provide an improper guide for future enhanced visualization of the current 2D land use surface. This study aims to visualize the influence of georeferencing on IEOF simulation when represented by volumetric soft geo-objects within a 3D environment, which is driven by the physically based Green-Ampt method. Visualization is analyzed by focusing on infiltration and overland flow processes using the conformal-based Malaysian Rectified Skew Orthomorphic (MRSO) and the equidistant-based Cassini-Soldner projection. Appropriate usage of a georeferencing system to visualize 3D dynamic IEOF simulation may see high demand from civil engineers, environmentalists, town planners, geologists, and meteorologists as a basis for producing scientific results in flood management control, sustainability for long-term development purposes, stream restoration, rehabilitation, and hydrologic impact assessment.