The monitoring of wetlands and water extents plays more and more an important key role with respect to climate change. In this paper, a novel technique of SAR image preprocessing using multi-temporal, multi-polarized and multisensor data is described. This technique bases on the Kennaugh element framework which is a very versatile polarimetric descriptor on the one hand and enables an effective image enhancement technique on the other hand. The two practical examples given in this paper illustrate further advantages of the Kennaugh element framework in change detection and change characterization used for the monitoring of temporal variations of the water extent and therewith, the water level and the water quantity.