Dewatering techniques are methods used to remove excess water from soil or sediment, making it easier to work with. Common techniques include drainage, where water is redirected away from an area, and pumping, which involves using pumps to extract water from a site. These methods are essential in construction, mining, and environmental management. Another technique is surcharge, where weight is added to compress soil and expel water. Additionally, geotextiles can be used to filter water while allowing soil to remain in place. Each technique is chosen based on the specific conditions and requirements of the project.