Underwater sensors technology has experienced a tremendous development over the last decade. They have generated considerable community enthusiasm, which applied them to a wide range of cases that could enhance human and animal habitat conditions e.g. climate changes prediction or pollution surveillance. In this paper, we address the issue of deploying a UWSN in an area characterized by the geographical irregularity of the sensed event. Our specific application context regards the monitoring of the water quality in a small closed area (e.g. a lake). For this purpose, we propose a differentiated deployment algorithm (DDA) based on a mesh representation method inspired from the image processing and 3D modeling field.