It does look better as it makes the rivers look narrower but the shading is a bit extreme considering the scale. The rivers you shaded look like gorges and it's gonna be pretty hard to make them not look like this I guess. Perhaps try lowering the opacity of the shadow/highlights layer by, say, 15-20 % tops just to se how it fares.

That or ... add another layer with the initial shading expanding further from the river and lower the opacity of that layer to create a transition.