なぜ？消える海水浴場の砂浜　「茨城のゴールドコースト」は海開き断念【スーパーJチャンネル】(2026年7月17日)

A popular beach has decided to cancel its summer season. The reason? "The disappearance of the sandy beach." What is happening to Japan's coastlines? Some studies predict that over 60% of beaches will disappear by 2100. ■Why? The disappearance of beach sand The beach in Yaizu City, Shizuoka Prefecture, opened for the season on the 17th. Energetic children are enjoying the sea. While the full-fledged swimming season has begun, there was a beach in Ibaraki Prefecture that was unable to open. This is the "Otake Kaigan Hokota Beach." With its unobstructed, straight stretch of sandy beach and beautiful scenery, it's known as the "Gold Coast of Ibaraki," and is a popular spot that usually attracts over 20,000 beachgoers every year... but this summer, part of it is closed to the public. The reason is "the disappearance of the sandy beach." Previously, many tents were set up on the beach, and a beautiful sandy shore stretched out before us... but now the area of ​​the beach has drastically decreased, and there is no space to pitch tents. The waves were crashing right up to the shore. When the program previously covered this location, only six layers of concrete blocks were visible, but now the sand has drastically decreased, exposing blocks that were previously hidden. The sand that was originally there is gone, leaving holes in the blocks. Hokota City has decided to cancel the beach opening, considering safety concerns. The cancellation of the beach opening has affected nearby restaurants... Takuya Onuma of Restaurant Uminokaze: "Some people come to the beach for swimming and then stop by the restaurant. I think there will be an impact." This restaurant is located right by the sea. At this time of year, ramen made with clams caught nearby is popular. The swimming season is a particularly busy time of year for the restaurant, with around 400 customers visiting on weekends... Takuya Onuma: "I think about 50 to 100 people will be affected. There are customers who are looking forward to enjoying the sea, so while it's difficult due to natural phenomena, I hope they can open the beach." Why did the beach erosion occur? Takayuki Shiota, Ibaraki Prefecture River Division: "One major factor is the decrease in the supply of sand to the coast." According to Ibaraki Prefecture, which manages the coast, the Kashima Sea, where Hokota Beach is located, has maintained its sandy beaches through sediment carried by waves from the Naka River and Tone River. However, the amount of sediment has drastically decreased compared to the past. The reason for this is the urbanization of the river basin. Takashi Shiota: "Dams are being built upstream, urbanization is progressing and former farmland is being turned into asphalt, making it harder for sediment to flow into the river. Concrete revetments are being built in the rivers, and various other factors are having an impact, resulting in a decrease in the amount of sediment supplied from the river into the sea compared to the past. Erosion is occurring." Two years ago, the beach opening was canceled due to beach erosion. The following year, construction work was carried out to transport sand to the coast, and the beach was able to open, but the sand that was added was washed away, and the beach eroded again. The construction cost around 40 million yen, and it is said that adding sand every year is costly. Takashi Shiota: "Continuing this indefinitely is not cost-effective in the long run." ■ 60% disappear by 2100? This "disappearance of sandy beaches" is not limited to Ibaraki Prefecture. The beach in Katagami City, Akita Prefecture, once bustling with swimmers, is now experiencing increasing erosion, with most of the sand covered by waves. Beach erosion is progressing throughout Japan, and the number of beaches unable to open for swimming is growing. According to research by Professor Udo and others at Tohoku University Graduate School, more than 60% of Japan's beaches may disappear by 2100. Is there a way to restore the lost beaches...? [TV Asahi NEWS] https://news.tv-asahi.co.jp