Erosion in the limestone karst areas leads to runoff and silting. Artisanal mining degrades riparian zones, creating erosion and heavy silting of the water. The consequent silting will reclaim about of land. The Port of Rosario is subject to silting and must be dredged periodically. The soil gets eroded, and leads to silting in rivers and reservoirs. The silting of the harbour ultimately destroyed its prosperity. The barrage has caused progressive silting of the Rance ecosystem. During the early 1800s as trade was increasing, so the river was simultaneously silting up. However, constant silting changed the coastline. Salem and its silting harbor were increasingly eclipsed by nearby Boston and New York City. The algae is followed by weeds and ultimately a silting of water bodies. The silting of the Haven only furthered the town's decline. Both ports were eventually abandoned due to silting. The Indus Delta is also silting, which makes cultivation difficult. Seleucia Pieria, which was already fighting a losing battle against continual silting, never recovered.