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Why does the Jordan River’s flow decrease downstream?

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Arid, rugged hills and winding roads in the Jordan Rift Valley, with the Jordan River and a small reservoir visible in the distance. — Jordan River Portion of the Jordan Valley, a rift valley that runs north-south along the Jordan River.

The Jordan River’s flow decreases as it moves downstream primarily due to natural environmental factors and significant human intervention.

Natural causes include:
* Evaporation: The river experiences high rates of evaporation, particularly as it flows through the arid Jordan Valley where summers are torrid.1
* Seepage: Water is lost as it seeps away into the ground along the river’s course.1

Human activities have also substantially reduced the river's volume:
* Water Diversion: Both Israel and Jordan divert large quantities of the river's water for irrigation and municipal supply, which has significantly diminished the flow reaching the Dead Sea.12
* Damming: The construction of dams to control the river’s flow for agricultural use has reduced the contribution of major tributaries, such as the Yarmūk River, which once nearly doubled the Jordan’s flow.1