三合堰是都江堰外江灌区的骨干工程，灌溉崇州、大邑、邛崃三县（市）农田１．８３万公顷，１９５５年建成，至今已运行４０多年，工程老化，效益衰减，今年列为成都市农田水利基本建设八大工程之一，开始分段整治，第一期工程计划投资２００万元，护砌渠道３．１公里和１... Sanjiangyan is a key project of Dujiangyan Irrigation District, irrigating 18,300 hectares of farmland in Chongzhou, Dayi and Qionglai counties. It was completed in 1955 and has been in operation for more than 40 years. As the project ages and its benefits diminish, this year is listed as Chengdu, one of the eight projects of farmland water conservancy construction, began sub-section remediation, the first phase of the project plans to invest 2 million yuan, 3.1 km and 3.1 km of protection channel.