I may have missed this part of the rulebook, but how do I tell the difference between the high and low elevations? Are the high elevation regions just the beige ones without spots for dikes on their borders?
Yes, the high elevation regions are beige with stripes and have no places for dikes. They are 'buffers', the water doesn't go there. You can walk through them like through any region though (we forgot this in our first game sessions). 'Oost-Brabant' (high elevation region) is very handy to go from 'West-Brabant' to 'Roer en Overmaas' for example.