• 堤防ていぼう — embankment; levee; sea wall
• 防波堤ぼうはてい — breakwater; wave-blocking sea wall
• 河川堤防かせんていぼう — river embankment
• 堤つつみ — dike; bank along a river or lake
• 堤つつみを築きずく — to build an embankment

With the earth radical 土つち on the left, 堤 suggests earth piled up to hold something back. It’s the solid bank that stands between the water and the town, quietly absorbing the force of the river.