Understanding Streamflow Change at the Scale of a Major City: Chicago

Urban and economic development and climate change have made the non-stationarity of stream flow records an emerging phenomenon in hydrology. This thesis studies the systematic shifts in stream flow that have been observed in urban, suburban and agricultural watersheds in and around the Greater Chicago area. A novel statistical method, the Procedure for Change Pattern and Signi ficance (PCPS), is developed to detect non-stationarity and identify the timing and duration of these shifts in hydrologic records. This method uses the rank correlations of the Mann-Kendall statistics to extract information that can be interpreted to identify the timing and duration of a detected shift, while it also adopts the Mann-Kendall test to determine whether the change is statistically signi ficant. It is also shown that incorporating the aspects of timing, duration and signi ficance in a consistent analytical framework enables the issue of serial correlation to be tackled better. The proposed statistical framework is associated with conceptual modeling tools to understand how adaptive human responses to urbanization mitigate and sometimes even o ffset the e ffects of land-use change in a large urban area, such as the Greater Chicago area. Results of PCPS, along with an analysis of the recession process, show that while impervious surfaces increase flooding, stormwater management facilities mitigate or even counter this impact over a wide range of scales. On the other hand, an urban water balance shows that low flows have increased since the impacts of e ffluent discharges, pipe leakage and garden irrigation from municipal water systems using water from Lake Michigan outweigh the reduction of basefl ow due to impervious surfaces. In addition, the increasing trend of the mean flow in the area can be explained by the combined impacts of water withdrawals from Lake Michigan, land-use change and climatic variability. Finally, it is found that a step increase in rainfall coincides with a step increases in streamfl ow around 1970. Thus, PCPS detects the impacts of climate and urbanization on stream flow throughout the Greater Chicago area.

Name thesis:degree_name

M.S.

Level thesis:degree_level

Thesis

Discipline thesis:degree_discipline

Civil Engineering

Grantor

University of Illinois at Urbana-Champaign

Year dc:date

2010

Author dc:creator

• Roug��, Charles J.

Contributors dc:contributor

• Cai, Ximing

• shift
• timing
• duration
• statistical significance
• urbanization
• water withdrawals
• detention basins
• land-use change
• climate variability

Statement dc:rights

• Copyright 2010 by Charles Jacques Rougé. All rights reserved.

Language dc:language

en

Handle dc:identifier

http://hdl.handle.net/2142/16722

OAI identifier oai:identifier

oai:www.ideals.illinois.edu:2142/16722