A Simulation approach to model the relationship between building density, land use zoning and surface runoff levels in urban blocks : an innovative approach to manageurban flooding in Sri Lanka [abstract]

Abstract

The main objective of the study was to develop a framework to develop a spatial simulation approach to capture the dynamics of surface runoff with respect to alternative built form and land use scenarios in a given urban block. Accordingly, the study (i.) formulated and validated a set of geospatial models based on open source GIS application, to simulate the surface runoff and dynamic physical features (i.e., land use and building density) of selected urban areas respectively at a detailed spatial scale, (ii) validated and calibrated the applicability of the proposed approach with actual rainfall data and flood data in the context of a selected cities in Sri Lanka, (iii) introduced different LID scenarios to reduce surface runoff or to reduce the urban flood occurrences as individual level (building-wise), as well as urban planning decision-making levels (i.e., neighborhood and local planning levels), and (iv) assessed the applicability of the proposed simulation framework as a decision-making tool in spatial planning fields and share knowledge with relevant urban planning authorities and Town Planners in Sri Lanka. The results revealed that the proposed approach has the capability to measure and model the changes in flood levels and lag time under alternative Low Impact Development (LID) scenarios. The model is sensitive to future scenarios of population growth, uncontrolled urbanization (sprawl), changers of built form as an advanced regulatory tool for formulating development plans in order to make flood-free environment in future. Accordingly, the findings of the study can be utilized as a guide to the decision-making process in urban planning and design, and to formulate sustainable planning regulations and guidelines to cope with urban flooding under the precipitation uncertainty.