An integrated modeling approach for the assessment of land use change effects on wastewater infrastructures

Abstract

The simulation of sewage systems and wastewater treatment plants is a strategic aspect for assessing the effect of new dwellings on the existing water facilities. This constitutes a quite common problem, since usually new edification areas are planned without looking at the effect that new scenarios will cause on the existent infrastructures. In this Thesis integration of water pollution and land use change models is presented and applied to a case study. The water pollution is meant as the complex relationship between proposed housing development and wastewater pollution incident control. The aim of these models is about the impact of new edification areas on the existent watercourse. This Thesis introduces an integrated framework made by a land use change model, a sewage system simulator and a wastewater treatment plant simulator. This is a complex system since each element is characterized by different dynamics. The land use change model simulates the expansion of an urban area according to planners’ guidelines; the sewage system simulator investigates the response of the drainage system to the expansion as well as its flexibility. The wastewater treatment plant is simulated in order to assess the impact of the new inflowing discharges on the existing plant. This Thesis describes the motivation, the rational and implementation details of a modeling framework namely Stochastic System Dynamics Integrative Model (SSDIM), which is an effort to bridge the gap of integrated models for decision making in urban planning. By combining automatic decision support tools with an integrated framework that brings together land use change and wastewater network infrastructure, it enables the analysis of the effect of alternative long-term urbanisation plans on the quality of the surrounding environment, measured through water indicator. The functionality of the SSDIM was demonstrated through a semi-hypothetical case study, in which three planning scenarios were evaluated for a new housing area against the quality of the wastewater drained by a sewer system and eventually treated by a wastewater treatment plant. On the one hand, the study highlighted the flexibility in representing planning scenarios and settingup the sewer networks in the framework and demonstrated that the framework, as a conceptual and quantitative tool, can easily accommodate for the complexity involved in a real-world case study. On the other hand, the results emphasised that the framework was able to capture the evolving ABSTRACT 10 impact of urban planning over a long term period, which play an important role in understanding the existing system and environmental capacities, and thus SSDIM provides a valuable decision support aid in the urban planning process. In the first part of this Thesis, the setting and motivation for the framework proposed and an extensive review of the studies available from literature are discussed as well as the legal background related to the problem at stake The second part of the Thesis presents the elements of the models implemented: in particular, both the conceptual representation and the implementation details are discussed in depth. Finally in the last part of the Thesis, an application of the developed framework to a real world environmental problem and the results of the application of the framework to a case study is described. The case study represents a sewage network of a town located in south west of Scotland and its wastewater treatment plant, where some urban development scenarios are assumed