Looks like you want a savanna biome in the valley between the mountain ranges.

You can feed the water inland through rivers fed by glaciers in the mountains. They will then meander though the valley and leave through one of the gaps into the ocean.

You'll need to stop trees from growing in some way, either by frequent fires or a shallow soil layer.

Looks like you want a savanna biome in the valley between the mountain ranges.

You can feed the water inland through rivers fed by glaciers in the mountains and underground rivers/lakes. They will then meander though the valley and leave through one of the gaps into the ocean.

You'll need to stop trees from growing in some way, either by frequent fires or a shallow soil layer.