Where I live I am surrounded by black silty clay. Black clay takes ages to fill up with water, and once it does, it takes ages to drain. Currently the clay around me is a dry. It will take a large amount of rain, say 100 – 150 mm, to top up the clay. This needs to happen before the ephemeral stream will flow. My dam will not fill until this happens. Once my dam does fill, however, it will take a good year for the clay to dry out, meaning that relative small rain events, like 25 mm could recharge the dam. Taken a few years ago. During our last La Niña event. Added for Jennifer’s Wet
I was bit worried the dam may burst. But that thick old black clay held.