WATER MANAGEMENT BEFORE YUAN DYNASTY

Basically, water management recorded in historical documents was very limited before the Yuan Dynasty. The earliest document in the Han Dynasty recorded that some villages with paddy fields around Dian Chi lake existed before the Han Dynasty（BC 200）, people governed the Pan Long Jiang river to irrigate paddy fields and grow rice. In the Han Dynasty, the local governor，Mr. Zhang Bo, implemented dredges up the Pan Long Jiang river for extending irrigation and keeping floods away, this shows that agriculture and irrigation in this area has been developed for 2000 years（Ma Yao 2009）.

The most important period in early history for governing the Pan Long Jiang river was in the Song Dynasty. In 1040, Kunming City was built to be the east capital of Dali Kingdom, the local Kingdom of Yunnan（Ma Yao 2009）. As a result of the establishment of the east capital, many hydraulic engineering were implemented for water management. Firstly, the riverbank of Pan Long Jiang river was dredged to control flood and develop irrigation, and secondly, the most important hydraulic projects were two man-made rivers, Jing Zhi He river and Yin Zhi He river. These were built for irrigation and for leading floods from the Pan Long Jiang river（Fig.4）.

Fig.4 The sketch map of Pan Long Jiang Basin

Jin Zhi He river, with a length of 35km, starts from the Song Hua Ba dam and is linked to Pan Long Jiang river, flowing down to the lower area of Kunming City before finally flowing into Dian Chi lake. After the Jin Zhi He river was built, the king, Mr. Duan, asked people to plant masses of Yellow Flower（local name at the time）along the riverside. The reflection of the flowers in the water led to the river being called Jin Zhi He, it means the river of golden juice.

Yin Zhi He river, with a length of 17.6km, originates from the He Long Tian（Black Dragon Spring）and Bai Long Tian（White Dragon Spring）springs in the northern mountains of Kunming City, also receives water from many becks on the way before it flowing into the Pan Long Jiang river. This river irrigates largely paddy fields and especially reinforces much water to the Pan Long Laing river in winter, the dry season of the year, increasing the efficiency of irrigation in the lower basin of Pan Long Laing river. The king also asked people to plant largely Argentine flowers along the river sides, so it was called Yin Zhi He, meaning the river of silver juice（Kunming Water Work Bureau 1996）.