TABLE 3.
Summary Statistics for Basin Characteristics and Hydrologic Metrics Calculated for 16 Stream Basins.
| Variable | Description (units) | Minimum | Mean | Maximum |
|---|---|---|---|---|
| Basin characteristics | ||||
| Basin area | Drainage basin area (km2) | 9.6 | 28.8 | 53.5 |
| %TIA | 1998 total impervious area (%) | 9.5 | 33.5 | 58.5 |
| %Outwash | Surficial outwash deposits (%) | 9.7 | 24.6 | 56 |
| %Till | Surficial till deposits (%) | 18.4 | 35.3 | 67.7 |
| %Bedrock | Surficial bedrock cover (%) | 0 | 5.4 | 31.2 |
| %Urban | 1998 urban land cover (%) | 15.1 | 52.8 | 88.7 |
| %Forest (non-urban) | 1998 non-urban forest cover (%) | 4.8 | 38.2 | 80.8 |
| Basin elevation | Mean basin elevation (m) | 75 | 146 | 344 |
| Precipitation | Mean annual precipitation (mm) | 891 | 1192 | 1833 |
| Basin slope | Mean basin slope (%) | 6.7 | 10.0 | 21.2 |
| Local channel slope | Local channel slope (m/m) | 0.004 | 0.018 | 0.090 |
| Hydrologic metrics | ||||
| Qmean | Mean annual average flow (m3/s) | 0.153 | 0.490 | 1.267 |
| Low Pulse Count | Number of low pulse events per year (count) | 2 | 10 | 28 |
| Low Pulse Duration | Mean duration of low pulse events (days) | 7 | 26 | 93 |
| Low Pulse Range | Range each calendar year over which low pulse events occur (days) | 67 | 207 | 341 |
| High Pulse Count | Number of high pulse events per year (count) | 2 | 10 | 22 |
| High Pulse Duration | Mean duration of high pulse events (days) | 2 | 7 | 31 |
| High Pulse Range | Range each Water Year over which high pulses occur (days) | 34 | 168 | 306 |
| Fall Rate | Average fall rate of falling flows (m3/s per day) | 0.035 | 0.098 | 0.244 |
| Rise Rate | Average rise rate of rising flows (m3/s per day) | 0.059 | 0.190 | 0.518 |
| Fall Count | Number of falling flows (count) | 25 | 92 | 137 |
| Rise Count | Number of rising flows (count) | 42 | 68 | 86 |
| Flow Reversals | Number of flow reversals per year (count) | 37 | 55 | 70 |
| TQmean | Fraction of year that daily flow exceeds mean annual flow (fraction of year) | 0.25 | 0.31 | 0.38 |
| R-B Index | Richards-Baker Flashiness Index (unitless) | 0.08 | 0.27 | 0.49 |
| Seven-day minimum | Minimum seven-day moving average flow (m3/s) | 0.005 | 0.092 | 0.283 |
| Date of annual daily minimum | Date of annual daily minimum flow (Julian date) | 146 | 239 | 311 |
Note: Hydrologic statistics based on up to three years of data collected in years prior to and including the year benthic invertebrate samples were collected.