ציטירנדיקער פּירוש אויף שמואל ב 24:5

וילך..בנחל גרר. The word נחל describes a valley even though there was no river in that valley. We have another example of this in Deuteronomy 2,36 העיר אשר בנחל, “the city which was located in the valley,” or Samuel II 24,5 ימין העיר אשר בנחל, “to the right of the city in the valley.” The most potent proof for our statement is Genesis 26,19 ויחפרו עבדי יצחק בנחל, “the servants of Yitzchok dug in the valley.” If there had been water, a rivulet, or something in the valley, what did they have to dig for? Gerar was the name of the town in that valley, the place where Yitzchok settled. He dug many wells in that region as he owned much livestock and had to provide water for his beasts.