Based on a large number of domestic and foreign literatures, the annual and monthly rainfall data of Dalian 1905-200 1, the daily rainfall data of 195 1-200 1 and the short-term rainfall data from 2003 to 2005 were systematically analyzed. The siphon self-recording rain gauge installed in the campus of Dalian University of Technology was used to monitor dozens of rainfall processes. The characteristics of rainfall in Dalian are analyzed, and the frequency curve is calculated and drawn. In particular, the time characteristics of heavy rain that caused serious harm were analyzed. The time characteristics of annual, monthly, daily and short duration of heavy rain in Dalian are obtained, and the characteristics of rain pattern are analyzed preliminarily. Relevant theories and methods are put forward for the rainwater resource utilization model. Finally, taking the campus of Dalian University of Technology as an example, the campus rainwater utilization planning is put forward, and the rainwater quantity calculation and reservoir design are carried out, which improves the theory of rainwater recycling.
Through the analysis of rainfall data, experimental research, mathematical analysis and example calculation, this paper mainly draws the following results and conclusions: (1)
The average annual rainfall in Dalian is 607mm, which is unevenly distributed during the year. From June to September, the average annual rainfall accounts for 72.5% of the annual rainfall, and the difference between the maximum and minimum annual rainfall is as much as 4.4 times, indicating that the rainfall in Dalian varies greatly from year to month.
(2)
The number and quantity of annual rainstorm in Dalian are random, but under the condition of decreasing annual rainfall for many years, the annual rainfall of rainstorm has an obvious increasing trend. Most heavy rains occur from June to September every year, with obvious seasonality. Among the rainstorm rain patterns, there are few uniformly distributed rain patterns, most of which are non-uniform rain patterns, with single peak rain as the main one, and the proportion of double peaks or multi-peaks is very small. Single peak rain, there are many rain peaks in front, and there are few rain peaks in the middle or behind. Heavy rain produces heavy rainfall in a short time, and the shorter the interval time scale of heavy rain, the greater the average rainfall intensity.
(3)
Taking the campus of Dalian University of Technology as a typical experimental area, the rainwater resources are planned, the rainwater collected by various land use types is calculated respectively, and the storage tank volume is designed. According to different types of rainwater utilization, the water requirements for flushing, greening and sprinkling campus toilets are calculated.