Alrighty;
First, you're using a lot of colours for each depth of water, you should be able to get by just fine with 3.
I'd suggest making the shallow water 50% Deep Water and 50% Wet Sand
Don't make the details just squiggly lines, have a look at this:

The surface reflections of light are much larger than an arbitrary 1 pixel line.
Now, is this for a lake or a beach? Because if it's a beach the only way you can deal with the transition between land and water is going to involve waves, at least for the shore.
There are some nice photos of a beach hereOr if you're going for a lake, maybe this will help:
