When Abraham and Isaac dug wells where today is the Negev desert at Beersheba, the wadi Beersheba was a perennial stream flowing west from the Judean Hills, the landscape was verdant, pastureland and forest, during the Ice Age (which followed Noah’s Flood). The wells were dug for clean drinking water (without animal and human waste), so don’t be fooled into thinking Beersheba was as dry circa 2000 b. c. as it is today, where now a few inches of rain falls per year but during the Ice Age twenty to thirty inches.