Statistical analysis shows that mean annual base flows in three unregulated urban streams in northeastern Illinois do not display significant trends during periods of substantial watershed urbanization. However, statistically-significant upward trends in median annual base flow (probably emblematic of overall changes in the time-distribution of the base flow), characterized by increases in lower base flow rates, affected the flows in all three streams. The analysis reveals no trends in annual and monthly precipitation during these periods. These results are in contrast to results from studies of other urban streams that have shown decreases in base flow, but these results may be partially explained by the low permeability of the near-surface materials in the watersheds investigated. This study employs formal hypothesis-testing of Kendall tau-a trend statistics computed for monthly and annual base flow and precipitation rates to assess the impact of urban development on base flow rates.
- Groundwater recharge/water budget
- Groundwater/surface-water relations
- Midwestern USA
- Urban groundwater
ASJC Scopus subject areas
- Water Science and Technology
- Earth and Planetary Sciences (miscellaneous)