The Influence Of Wohushan Reservoir To Jinan Karst Spring Basin

High-frequent human activities have seriously affected the underlying surface in most basins, especially with the accelerated progress of urbanisation in recent years. Those reservoirs and barrages built in recent years are changing the runoff characteristic of rivers. In addition, the transformation law between surface water and ground water are changed. In order to make full use of the cherish water resources, it is essential important to study the reservoir's impact on it. Taking Wohushan reservoir in Licheng district, Jinan city as an example, this paper discusses the influence of Wohushan reservoir to Jinan Karst Spring Basin.Located in the recharge area of Jinan Karst Spring Basin, Wohushan reservoir is one of the most important recharge sources to the spring basin. The river bed of Yufu River is largely made of gravel, directly contacted with the limestone beneath the river bed. Due to Yufu River's strong infiltration ability in the midsection, the surface water can infiltrate into the ground water directly.Two research methods are used to study the infiltration ability of Yufu River: One, the artificial recharge experiment revealed that the infiltration ability is 7.54m3/s at least. The second method comes from the research of typical flood data. Lots of variable factors affect the infiltration ability of the river and we take 15m3/s as reasonable conclusion.Before the completion of Wohushan reservoir, only there years of runoff data, which is1957~1959 remained. Taking into consideration of data integrity and data consistency, runoff data from 1971 to 2004 are analyzed. Yufu River belongs to typical rain source rivers under natural condition and the runoff mainly concentrate in flood season. Annual runoff is 6843 million cubic meters and among which the runoff in three months from July to September make up about 69.1 percent of the total, runoff in February is least which only accounts for 1.6 percent of the total. In the 34 years, maximumrunoffrate number which larger than 50 cubic meters per second is 32, and the amount of flow accounts for 34 percent of the total flow.After the completion of Wohushan reservoir, the total amount of runoff from 1971 to 2004 is 4407 million cubic meters, which is only 64.4 percent of the amount under natural condition. Wohushan reservoir greatly changed the runoff characteristic of Yufu River.On condition that the infiltration ability is 15m3/s, the recharge of ground water to Jinan Karst Spring Basin is analyzed, together with the influence of irrigation to ground water, we draw the conclusion that due to the construction of Wohushan reservoir, annual artificial recharge reduces 2302 cubic meters, which is about 47 percent of influence to the Jinan Karst Spring Basin.