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

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

Roug��, Charles J. ; Cai ; Ximing

关键词: shift;    timing;    duration;    statistical significance;    urbanization;    water withdrawals;    detention basins;    land-use change;    climate variability;   

Others  :  https://www.ideals.illinois.edu/bitstream/handle/2142/16722/rouge_charles.pdf?sequence=2&isAllowed=y

美国|英语

来源: The Illinois Digital Environment for Access to Learning and Scholarship

【 摘 要 】

Urban and economic development and climate change have made the non-stationarity of stream flowrecords 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 theGreater 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 theseshifts in hydrologic records. This method uses the rank correlations of the Mann-Kendall statisticsto extract information that can be interpreted to identify the timing and duration of a detectedshift, while it also adopts the Mann-Kendall test to determine whether the change is statisticallysigni ficant. It is also shown that incorporating the aspects of timing, duration and signi ficancein 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 understandhow adaptive human responses to urbanization mitigate and sometimes even o ffset the e ffects ofland-use change in a large urban area, such as the Greater Chicago area. Results of PCPS, alongwith an analysis of the recession process, show that while impervious surfaces increaseflooding,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 lowflows have increased since the impactsof e ffluent discharges, pipe leakage and garden irrigation from municipal water systems using waterfrom Lake Michigan outweigh the reduction of basefl ow due to impervious surfaces. In addition,the increasing trend of the meanflow in the area can be explained by the combined impacts of waterwithdrawals from Lake Michigan, land-use change and climatic variability. Finally, it is found thata step increase in rainfall coincides with a step increases in streamfl ow around 1970. Thus, PCPSdetects the impacts of climate and urbanization on stream flow throughout the Greater Chicagoarea.