Evaluation of Integrated 1D-2D Modeling for Storm Drainage Networks

Abstract

1.1 General

The objective of highway storm drainage design is to provide for a safe passage of vehicles during the design storm event. The drainage system is designed to collect storm water runoff from the surface, conveyit along and through the right-of-way, and discharge it to a storm water conveyance system without causing harmful impacts.

Another definition for the objective of the storm water conveyance systems (storm drain piping, ditches and channels, pumps, etc.) is to provide an efficient mechanism for conveying design flows from inlet locations to the discharge point without surcharging inlets or otherwise causing surface flooding. Erosion potential must also be considered in the design of open channels or ditches used for storm water conveyance.)Ref. Hydraulic engineering circular No.22, third edition, urban drainage design manual)

Recent flooding events have revealed deficiencies in existing storm water infrastructure and management practices. The development of effective and efficient design requires a comprehensive understanding of flooding in urban areas and complex open channel and overland flow systems. Traditional one dimensional (1D) models are used to simulate flow in river channels and gravity collection networks but are inadequate for simulating phenomenon such as lateral flood spreading and overbank flow in flood plains that occurs during extreme events. 1D/2D and 2D models have begun to be used but their complexity, cost and significant data requirements have limited their application. The availability of high quality Digital Terrain Models (DTMs), high speed computers as well as the necessity of more accurate flood mapping have all contributed to the adoption of 2D and (1D/2D) models for flood plain mapping and the analysis of overland flows. (Ref. Evolution of an integrated 1D/2D modeling package for urban drainage)

1.2 Scope of Work

The case study of an existing storm network will be investigated by using several models as follows:

- 1D gradually varied steady flow model. - 1D gradually varied unsteady flow model. - Linked 1D/2D analysis model.

Comparisons between the three mentioned techniques will be carried out to investigate the different between their results, and hence provide guidance for design engineers about which one is more economic for the design of storm networks and how the 1D/2D concept could be used to solve the problems of existing but insufficient networks.

1.3 Organization of Work

This thesis is organized in six chapters as follows:

Chapter one:gives an introduction about the subject and the organization of the work and objectives.

Chapter two: presents brief notes and literature review about the hydrology and the hydraulics equations used in storm water network analysis, also summarized the equations used for the following cases: - 1D gradually varied steady flow. - 1D gradually varied unsteady flow. - Linked 1D/2D analysis

Chapter three:presents and describes the case study of Abu Dhabi Airport storm drainage network, the present situation of the existing storm network and problems associated with.

Chapter four:in this chapter the methodology proposed will be applied to the case study for the three mentioned cases. All proposed scenarios will be discussed in detail in this chapter, the results will be presented and output difference between all methods interpreted.

Chapter five: presents the main conclusions of the research and also states the recommendations to be taken into consideration in the future research work.