Simply create a White Solid, then make a trapezoid mask shape over your water footage with the Pen tool (get it? so it would look like the sun is far away), then, simply play with the Blending Modes (maybe Add would be good). After that, you could play with the mask feather or add the Glow effect by adjusting the Glow Radius.
Hope that helped.
Justin Productions
Tangerin01@hotmail.com
Adobe After Effects 6.0 Professional