Roland K. Price

Coupled 1D and Noninertia 2D Flood Inundation Model for Simulation of Urban Flooding

Pluvial flooding in urban areas drained by storm sewer networks is characterized by surcharge-induced inundation. Urban inundation models need to reproduce the complex interaction between the sewer flow and the surcharge-induced inundation to make reasonable predictions of the likely flood damage in urban areas. In the framework of the present work, the storm sewer model SWMM5 and a newly developed two-dimensional (2D) noninertia overland-flow model have been coupled to simulate the interaction between the sewer system and the urban floodplain. The solution of the 2D model is on the basis of an alternating direction implicit scheme that solves the 2D noninertia free-surface shallow-water equations. For accuracy reasons, the time step is limited and controlled by the use of iteration to home-in on an accurate solution at each sweep. The dynamic interaction between the two models is bidirectional, and the interacting discharges are calculated according to the water level differences between the flows in the...

Multiobjective evolutionary approach to rehabilitation of urban drainage systems.

Urban flooding has become a very important and growing issue around the world. In order to maintain an acceptable performance of urban drainage systems, early rehabilitation plans must be developed and implemented. The allocation of funds to support rehabilitation works should be in a certain sense “optimal” in providing value for money. However, this is a highly demanding and not easily achievable task due to the multidimensional nature of the rehabilitation process, especially taking into account conflicting interests. In this respect, multiobjective optimization using hydrodynamic urban drainage models appears to be promising and more reliable than the traditional engineering approaches. Such optimization is used in this paper to evaluate urban drainage rehabilitation scenarios contrasting investment against flood damages. A small-scale rehabilitation problem is posed and solved. The approach has demonstrated the potential use and combination of multiobjective optimization and hydrodynamic models to an...

Effects of model schematisation, geometry and parameter values on urban flood modelling

One-dimensional (1D) hydrodynamic models have been used as a standard industry practice for urban flood modelling work for many years. More recently, however, model formulations have included a 1D representation of the main channels and a 2D representation of the floodplains. Since the physical process of describing exchanges of flows with the floodplains can be represented in different ways, the predictive capability of different modelling approaches can also vary. The present paper explores effects of some of the issues that concern urban flood modelling work. Impacts from applying different model schematisation, geometry and parameter values were investigated. The study has mainly focussed on exploring how different Digital Terrain Model (DTM) resolution, presence of different features on DTM such as roads and building structures and different friction coefficients affect the simulation results. Practical implications of these issues are analysed and illustrated in a case study from St Maarten, N.A. The results from this study aim to provide users of numerical models with information that can be used in the analyses of flooding processes in urban areas.

Ensemble Precipitation and Water-Level Forecasts for Anticipatory Water-System Control

Abstract A method is presented for testing weather forecast products for applications in anticipatory water-system control. The applicability of the ensemble prediction system (EPS) of the ECMWF is tested for flood control in a regional water system in the Netherlands. By performing long-term verification analyses, a full range of probability-threshold-based decision rules to apply anticipatory control actions is evaluated in terms of hits (correct alerts), missed events, and false alarms. The analysis includes forecast horizons from 3 to 9 days for extreme precipitation events and extreme water-level events. The water-level forecasts are prepared by feeding each member of the ECMWF EPS precipitation ensemble into a deterministic water-system control model. The current operational strategy is modeled to forecast when the routine operational control will not be sufficient to prevent high water levels, and therefore anticipatory control actions are needed. The results show that ECMWF EPS precipitation forec...

INNOVATIVE APPROACHES TO FLOOD FORECASTING USING DATA DRIVEN AND HYBRID MODELLING

Flood forecasting in rivers and coastal waters demands careful attention both to the reliability of the forecasts and the safety of the decisions made on the basis of the results. Advances in data driven modelling have improved the accuracy of forecasts made using physically based models. The hybrid modelling approach combines the best features of physically based and data driven modelling, either through a combination of their outputs, or using the latter to estimate residual errors and associated confidence bounds of the former. Whereas artificial neural networks are the usual data driven models used for these purposes, increasingly other techniques such as M5 model trees are proving to be as, if not more, powerful because of their focus on localized modelling and higher transparency for practitioners. This paper draws attention to the innovative use of such techniques for flood forecasting in rivers.

Framework for Anticipatory Water Management: Testing for Flood Control in the Rijnland Storage Basin

AbstractAnticipatory water management uses weather forecasts and water system simulation models to take operational water management actions before an event occurs. In this paper a framework consisting of the different steps and challenges of developing and evaluating an anticipatory water management strategy is discussed. The framework makes use of recent developments in ensemble weather forecasting and modeling of controlled water systems. In particular, flexible water-system control models enable simulation of a wide range of control strategies in multiyear hindcast analyses. With the increasing number of archives for weather forecasts and water-system-state variables, and the reduction in computational time resulting from increasing processor speed and parallel computing, hindcast verification analysis will become the basis for development and optimization of new operational water management strategies. The framework is successfully applied to a flood control case study in the Netherlands. Archived en...

Toward Flood Routing in Natural Rivers

AbstractFloods in rivers can be modeled with one dimensional flood routing methods, which include an approximate solution of the one-dimensional (1D) Saint-Venant momentum equation and a solution o...