INTRODUCTION

Kunming City is located at the north bank of Dian Chi lake（it is the largest fresh water lake in Yunnan province and the sixth largest fresh water lake in China, 306.3km2 in size）, having a narrow zone between the lake and mountains（Fig.2）. Naturally, the location of Kunming city is the upper basin of the sub water-system of the Yangtze River. Water resources in the city consist of the Dain Chi lake and six main rivers, but the water resources in this city are mainly from Pan Long Jiang, the largest river from The north mountains into Dian Chi lake. Historically, the lake was used by the local residents for fishing，transportation and limited irrigation, and after the 1960s it was also used for the water supply of Kunming City. After the early 1990s, the water supply was stopped due to its growing pollution. The foundation of livelihood for most of the residents of Kunming from its original history to 1960s were agriculture and fishing, but fishing just for the people settled closely around the lake, most of the residents relied on agriculture, so these rivers are the most important water resource for the livelihood of the city.

Fig.2 A bird's-eye view of Kunming City

Pan Long Jiang river is the only large river flowing across the urban area of Kunming City, its basin consists of a series of branch rivers, but the main branch rivers such as the Jin Zhi River and the Yin Zhi River were man-made in the twelfth century. Pan Long Jiang river has a total length of 104km including 37km in the urban area. It originates from the north mountains of Kunming City，from a high area（around 2200m a. s. l.）flowing into a flat urban area（around 1800m a. s. l.）As result of this difference frequent flooding has been recorded. According to historical documents, there were six large floods have been recorded in the past 700 years, for example, the largest was in 1857（Yunnan General-graphy. Written in Middle 19 century）. Documents recorded that flooding water was at a depth of 9.5m, all houses outside the round-town wall were destroyed and hundreds of thousands of people died. However, on the other hand, Pan Long Jiang river has played an important role in local irrigation and city water supply from the city's early age. Control and development of the usage of the river has been most important for local governments over the past thousand years. People have to control flood from Pan Long Jiang river and also develop ir rigation systems for extending farmland, so many water projects for control flooding and developing irrigation have been implemented in different periods of the city's history. The key, and largest, hydraulic engineering, Song Hua Ba dam, was built in 1275（Yuan Dynasty of China）. After the dam was constructed, flood was effectively controlled in general, and Kunming City developed as a large city and an economic, political center of Yunnan province. After the Yuan dynasty, the Song Hua Ba dam has been rebuilt numerous times until the 1980s, so we can say that the history of Kunming City was developed along with this dam, mainly achieved on Pan long Jiang river's control and water management.

Dian Chi lake is an inland lake. It receives water from the north mountains mainly by Pan long Jiang with drainage by the Hai Kou river, the draining mainstream of Dian Chi lake. Hai Kou river starts from the west bank of the lake and flows into the branch of the upper reaches of the Yangtze River. The function of the river was mainly for balancing the water level of the lake due to the water level regularly rising by receiving water in summer, therefore bringing frequent flooding to the banks of the lake, especially after the Pen Long Jiang river basin was effective in governing, water in the north area of the lake was leaded smoothly by Pen Long Jiang river into the lake but also brought rising water levels and caused more flooding in summer. As a result, impactful drainage of the lake was used to reduce the flooding, so the governing of Hai Kou He river become another main effort for the city's water management from the twelfth century to later centuries. After the river was governed, causing a decline in the water level of the lake, farmland emerged around the lake that also brought great possibilities for the development of the city（Fig.3）.

Consequently, as the subsystem of upper Yangtze River, the water system in Kuming area is combined with Pan Long Jiang river, Dian Chi lake and Hai Kou He river. Correspondingly, the water supply system in Kunming City consisted of parts of Pan Long Jiang, Dian Chi lake and Hai Kou He river with its functions of leading water, keeping water and drainage. Historically, hydraulic engineering was mainly focused on: 1）Pan Long Jiang river governance for water supply, control flooding and irrigation;2）Hai Kou He river governance for drainage of the lake and balancing water in the lake. Implemented hydraulic projects brought the possibility of extending Kunming City's size and agricultural development and, finally, population growth. Simultaneously, as a result of the main hydraulic engineering, water management was implemented by local government on the entire periods of the city's history, just the becks in the residential area were managed by the local resident（Huang 1974）, so water governance（governments takes charge）was the main way forward for water management.

Fig.3 The water system of Kunming City