Groundwater recharge

Most groundwater recharge originates as precipitation. Irrigation contributes additional water in some areas (the net effect on groundwater resources may be positive or negative, depending on whether the irrigation water comes from groundwater or surface water). Some of the water runs off the land surface or evaporates from wet surfaces. The remainder infiltrates the soil, where it is subject to uptake by plants through transpiration (the combined effect of evaporation and transpiration is referred to as “evapotranspiration”). Illustration and description from: McLean, Jared H., Rotzoll, Kolja, Cleveland, Sean B., and Izuka, Scot K., 2019, The Hawaiʻi Groundwater Recharge Tool: website at https://recharge.ikewai.org.