Investigation of stormwater runoff at the Sleepy Hollow neighborhood, Fort Irwin, California

Authors: LEVICK - Retired Non ARS Employee; Goodrich, David; OLYMPIO, B. - University Of Arizona

Submitted to: Ag Data Commons
Publication Type: Research Technical Update
Publication Acceptance Date: 9/25/2024
Publication Date: 10/6/2024
Citation: Levick, Goodrich, D.C., Olympio, B. 2024. Investigation of stormwater runoff at the Sleepy Hollow neighborhood, Fort Irwin, California. Ag Data Commons. https://doi.org/10.15482/USDA.ADC/27327498.v1.
DOI: https://doi.org/10.15482/USDA.ADC/27327498.v1

Interpretive Summary: In arid and semi-arid regions, low precipitation can lead to reliance on groundwater for our needs. A study was conducted in cooperation with the Environmental Protection Agency and the Agriculture Research Service (ARS) in Riverside, California in the residential area of the Ft. Irwin Army base in southern California. The base only receives an average annual precipitation of 4 inches. An objective of the study was to see if enough runoff was generated in the residential neighborhood to enhance the recharge of groundwater. Rainfall, runoff, and characteristics of the watershed draining to a detention basin were studied. The basin in turn drains into a dry well that is designed to enhance deep infiltration to groundwater. Three storm events with all instrumentation working properly were observed. The respective percentage of the rainfall measured as runoff was 9, 5 and 11 percent. These events were modeled with the uncalibrated ARS KINEROS2 watershed model using urban overland flow model elements. For EV1 and EV3 the percent difference between simulated and observed runoff was -9.7 and -14.1 percent, respectively. For EV2 the model overpredicted the observed runoff by 80.2 percent. However, EV2 was a very small runoff event where the measuring resolution of the rain gauges (0.25 mm) translated into 57% of the observed volume. To generate substantial volumes of runoff for groundwater recharge would require a much larger developed area than the one studied herein. In addition, a larger sample size of events, with all instruments in proper working order, would lend greater weight to overall understanding of the character of rainfall-runoff processes at Ft. Irwin.

Technical Abstract: In arid and semi-arid regions, low precipitation can lead to reliance on groundwater for our needs. A study was conducted in cooperation with the Environmental Protection Agency and the Agriculture Research Service (ARS) in Riverside, California in the residential area of the Ft. Irwin Army base in southern California. The base only receives an average annual precipitation of 4 inches. An objective of the study was to see if enough runoff was generated in the residential neighborhood to enhance the recharge of groundwater. Rainfall, runoff, and characteristics of the watershed draining to a detention basin were studied. The basin in turn drains into a dry well that is designed to enhance deep infiltration to groundwater. Three storm events with all instrumentation working properly were observed. The respective percentage of the rainfall measured as runoff was 9, 5 and 11 percent. These events were modeled with the uncalibrated ARS KINEROS2 watershed model using urban overland flow model elements. For EV1 and EV3 the percent difference between simulated and observed runoff was -9.7 and -14.1 percent, respectively. For EV2 the model overpredicted the observed runoff by 80.2 percent. However, EV2 was a very small runoff event where the measuring resolution of the rain gauges (0.25 mm) translated into 57% of the observed volume. To generate substantial volumes of runoff for groundwater recharge would require a much larger developed area than the one studied herein. In addition, a larger sample size of events, with all instruments in proper working order, would lend greater weight to overall understanding of the character of rainfall-runoff processes at Ft. Irwin.