| Through measurement of unsaturated hydraulic conductivity (K) using the steady-state centrifuge method, point recharge estimates have been obtained at 11 locations in and adjacent to a 28-km reach of Abo Arroyo. Core samples were collected from depths where soil-moisture fluctuations are assumed negligible, so that downward water flow is steady and driven by gravity alone. At this depth, the value of K at the field water content of the core sample can be interpreted as a point recharge rate. Recharge appears to be significant at locations within Abo Arroyo (channel recharge), ranging from 0.12 to 2700 cm/yr, whereas recharge at locations 3.5 to 500 m away from the arroyo (inter-arroyo recharge) is less than 0.015 cm/yr. Integration of point recharge estimates through interpolation and geologic interpretation results in a total recharge estimate of 1300 acre-ft/yr within Abo Arroyo and 970 acre-ft/yr over the entire inter-arroyo region of the basin. |
