The extent to which humans manage the natural environment is starkly apparent in this scene over the Netherlands. Most of the tan portions of this scene are land that lies below sea level and was reclaimed from the North Sea (dark blue). Some of the most recently reclaimed land — referred to as polders — is visible in the righthand (southwest) side of this image. At the entrance to the bay is a large dike (thin, straight line) that has effectively turned the estuary behind it into a shallow, salty lake. Large areas behind this dike were then isolated with additional dikes. Extensive pumping of water behind this second system of dikes eventually exposed the sea bottom.
Once drained, each of these land parcels was sown with plants to remove moisture and bind the soil. Rainfall helped to remove salts from the soil. Subsequently the plant cover was burned and plowed under. From the time the dikes are in place, it takes approximately 15 years before the land is ready for planting. Since the twelfth century, more than 7800 square kilometers of land has been reclaimed from the sea by the Dutch.
Recovering coastal lands by various means is a fairly common practice throughout the world. Simple filling of low-lying coastal areas is another method of reclaiming land from the sea. This method has been employed to augment the land areas around cities such as Venice, Boston, and Tokyo. Barrier islands fringed with white beaches are found offshore in the lower left. The white streak originating in the upper lefthand (northeast) corner of this scene is an airplane contrail.
August 1997, image STS-85-735-7.