The second picture from the top is what didn’t seem to fit the water flow theory to me. The stalks seem to be flattened towards the ridge row, including the ones along the edge. I don’t know. I’d be interested to understand how that pattern could happen. The rest of the pictures, certainly water flow could be the culprit. My experience is with winter wheat when an early thunderstorm comes rolling through close to harvest. Sometimes the whole field is flattened, sometimes little bits of it.