Dunes are threatened by human activity, both intentional and unintentional. Countries such as the United States, Australia, Canada, New Zealand, the United Kingdom, and Netherlands, operate significant dune protection programs. Stabilizing dunes involves multiple actions. The main one is planting vegetation, that reduces the impact of wind and water. This abstract aerial view shows a circular swale being ready for an upcoming tree planting. at the Imperial Sand Dunes, the largest mass of sand dunes in California. This dune system extends for more than 40 miles along the eastern edge of the Imperial Valley agricultural region in a band averaging five miles in width.