Continuity vs. the Crowd-Tradeoffs Between Continuous and Intermittent Citizen Hydrology Streamflow Observations.

Area of Science:

• Hydrology
• Environmental Science
• Water Resource Management

Background:

• Traditional hydrologic data collection relies on expensive, fixed equipment, limiting spatial coverage.
• Citizen Hydrology offers a scalable, cost-effective alternative using mobile technology and local residents.
• The impact of reduced observational frequency on streamflow statistics accuracy is not well understood.

Purpose of the Study:

• To evaluate how decreased observational frequency affects the accuracy of key streamflow statistics (minimum flow, maximum flow, runoff).
• To assess the feasibility of Citizen Hydrology for collecting valuable hydrologic data.

Main Methods:

• Utilized 7 years of historical 15-minute streamflow data from 50 USGS gauges in California.
• Employed a bootstrap randomized subsampling procedure to simulate lower-frequency observations (daily to monthly).
• Calculated minimum flow, maximum flow, and runoff statistics and their distributions from subsampled data.

Main Results:

• Minimum flow estimates were within 10% for half of iterations at 39 (daily) and 23 (monthly) sites.
• Maximum flow estimates were within 10% for only 7 (daily) and 0 (monthly) sites.
• Runoff volume estimates were within 10% for half of iterations at 44 (daily) and 12 (monthly) sites.
• Watershed flashiness significantly influenced the accuracy of all estimated streamflow statistics.

Conclusions:

• Lower-frequency Citizen Hydrology observations can provide useful hydrologic information, depending on the specific research questions.
• Accuracy of streamflow statistics, particularly maximum flows, is sensitive to reduced observational frequency.
• Citizen Hydrology shows potential for expanding hydrologic data collection, but limitations regarding accuracy must be considered.