The Targum Pseudo-Jonathan adds a detail the plain Hebrew only implies. "And when Izhak went forth from Gerar the wells dried up, and the trees made no fruit; and they felt that it was because they had driven him away" (Genesis 26:26).
The land itself registered the loss. The wells refused to flow. The trees refused to bear. And the people of Gerar, the Targum tells us, felt it — they understood, in their bones, that a righteous man had taken his blessing with him when he left.
The righteous as a blessing on the place
The Talmud in Megillah teaches that a tzaddik brings blessing to the city he lives in. Rabbi Yochanan would say the righteous are the foundation of the world. When Isaac, whom the text has just called blessed by God, leaves Gerar, the blessing leaves with him. The rain does not fall the same way. The grapes do not swell the same way. The Philistines notice.
Pseudo-Jonathan is making a subtle theological argument. Blessing is not abstract. It is material. It makes wells flow and trees fruit. When Abimelech and Phicol, the chief of his army, come chasing after Isaac, they are not chasing a man. They are chasing the water and the harvest they did not know they had until they lost it.
The takeaway
The world is thicker than it looks. The Targum insists there is a subtle economy that connects who you drive away and what flourishes afterward. Pseudo-Jonathan's Gerar learned this the hard way. The wells do not lie.