used heat and cool the rocks until they cracked and could be removed. After eight years of work, a -wide channel had been gouged through the mountain. Legacy After the system was finished, no more floods occurred. The irrigation made Sichuan the most productive agricultural region in China. The construction is also credited with giving the people of the region a laid-back attitude to life; by eliminating disaster and ensuring a regular and bountiful harvest, it has left them with plenty of free time. The original Dujiangyan irrigation system was destroyed by the 1933 Diexi earthquake. The current Dujiangyan irrigation system was rebuilt by Zhang Yuan and his sons after the Diexi earthquake in 1933. Zhang Yuan and his son refer to Zhang Yuan (张沅) and his son Zhang Shiling (张世龄). In 2000, Dujiangyan became a UNESCO World Heritage Site. Today it has become a major tourist attraction in Sichuan. 2008 Sichuan earthquake On May 12, 2008, a massive earthquake struck a vast portion of west Sichuan, including the Dujiangyan area. Initial reports indicated that the Yuzui Levee was cracked but not severely damaged. Diversion of flow could still be seen as the river turns. Engineering constructions Irrigation head The irrigation system consists of three main constructions that work in harmony with one another to ensure against flooding and keep the fields well supplied with water: The Yuzui or Fish Mouth Levee, named for its conical head that is said to resemble the mouth of a fish, is the key part of the construction. It is an artificial levee that divides the water into inner and outer streams. The inner stream is deep and narrow, while the outer stream is relatively shallow but wide. This special structure ensures that the inner stream carries approximately 60% of the river's flow into the irrigation system during dry season. While during flood, this amount decreases to 40% to protect the people from flooding. The outer stream drains away the rest, flushing out much of the silt and sediment. The Feishayan or Flying Sand Weir has a -wide opening that connects the inner and outer streams. This ensures against flooding by allowing the natural swirling flow of the water to drain out excess water from the inner to the outer stream. The swirl also drains out silt and sediment that failed to go into the outer stream. A modern reinforced concrete weir has replaced