'Lollipop' model for gravity flow drainage network system

Pao Yue-kong Library Electronic Theses Database

'Lollipop' model for gravity flow drainage network system


Author: Ng, Chun-keung
Title: 'Lollipop' model for gravity flow drainage network system
Degree: M.Sc.
Year: 1998
Subject: Drainage -- Design and construction
Urban hydrology -- China -- Hong Kong
Urban runoff -- China -- Hong Kong
Hong Kong Polytechnic University -- Dissertations
Department: Multi-disciplinary Studies
Dept. of Land Surveying and Geo-Informatics
Pages: x, 131 leaves : ill. ; 30 cm
Language: English
InnoPac Record: http://library.polyu.edu.hk/record=b1437038
URI: http://theses.lib.polyu.edu.hk/handle/200/2340
Abstract: This research was to formulate a new model specifically designed for gravity flow drainage network with a view to integrating GIS network connectivity analysis, CADD presentation and hydraulic analysis. An object-oriented design approach has been used. Object-oriented design provides an easy way to stereotype a set of different but related objects beneath a single abstraction. This study started with the abstraction on the graphical presentation of drainage network shown on engineering drawings. Despite different methods of graphical presentations by different organizations, the smallest unit of a drainage network shown on a drawing unanimously consists of manhole symbol, straight pipe, label(s) and arrow. Network analysis requires the information of manhole and pipe, or in GIS terms, node and link respectively. A drainage network is in fact made up of a branched series of such unit. Further abstraction exercise found out that in most of the situations, say, on average more than 97%, a manhole is connected to one outlet pipe. This characteristic forms the basis for the development of a new graphic model called 'Lollipop'. A CAD-based system has been selected for the development platform. The development tools including ObjectARX provide a framework for the creation of custom objects. The Lollipop object is coined as a custom object in the system. This research uses an experimental approach and requires object-oriented programming in C++. Queries or analyses on GIS network connectivity, hydraulic calculation, geometrical properties and spatial conflict were performed in this research. Apparently, the model can live up to the expectation. Traditional GIS network analysis based on a higher level of abstraction relies on a topology composed of nodes and links in order to embrace a wider range of network simulations whereas Lollipop model is a lower level abstraction designed for specific properties of gravity flow drainage network.

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