The annual Dujiangyan Water-Releasing Festival was held on Friday in southwest China's Sichuan Province, marking the start of spring irrigation season and rice seedling breeding across the Chengdu Plain.

Set at the Dujiangyan Irrigation System, a renowned UNESCO World Heritage site, the festival portrays the historical origins of flood control in the Chengdu Plain.

Built more than 2,000 years ago and still functioning today, the system on the Minjiang River is one of the oldest irrigation systems in the world.

At the water-releasing ceremony, when the wooden triangular barriers are removed, clear water of the Minjiang River surged into the irrigation network that has fed the Chengdu Plain for over two millennia.

As spring irrigation enters its critical phase, with 8 million hectares already irrigated by the end of March, Friday's water release marks the end of the annual winter maintenance period and the beginning of the new farming cycle.

Groups of students are visiting the area and attending traditional activities while some learning to tie the wooden barriers used to block water.

This year's event was held on April 3, two days before the Qingming Festival or the Tomb-Sweeping Day, in keeping with historical customs while taking care of the spring break for primary and secondary school students in many parts of the country.