Decreases in streamflow over the past 100 years at eight long-term gauges in Hawai‘i

Figure 2-8  Base flow at eight out of the nine long-term streamflow gauges in Hawai‘i shows significant decreases of 20% to 70% over the past 100 years. This downward trend is consistent with significant decreases in rainfall in Hawai‘i. Because base flow comes from groundwater, decreasing base flow indicates decreasing groundwater resources; this has serious implications for Hawai‘i, where 99% of drinking water comes from groundwater (Oki, 2004; Bassiouni & Oki, 2012).

(From Oki, 2004, courtesy of the U.S. Geological Survey.)