Nahal Grar, which crosses the park, is the biggest tributary of Nahal HaBesor.
It begins in the area of Lahav, among the Judean foothills.
When it reaches the large loess plains of the Western Negev, near Tel Sera, the river does something. Its channel undermines the layers of silt and the loess to their full depth, under the layer of kurkar rocks, until it reaches the white chalk rock bed underneath them. These are obstinate rocks that are not prepared to allow the water to permeate through them and therefore a series of springs appear above them. In a rainy winter Nahal Grar flows almost continuously from Tel Sera to Tal Haror, for 80 km.
Water flows in the section of the river in Sharsheret Park for most of the year.
The Jordan Tamarisk trees and common reed thickets, two plants that benefit from the river's salty water, serve as a hiding place for many birds.
If you walk a short way along the river in the late afternoon and keep quiet, maybe you will be lucky and see a jungle cat stalking its prey.
In summer bee-eaters and rollers fly here – colorful birds that dig long tunnels for nesting in the soft loess cliffs.
A few meters west of Route 25, to the north of the park entrance, the scenic road crosses the arched bridge over Nahal Grar.
The road utilizes the old Route 25. The historical bridge was built in the period of the British mandate.