Discussion on Hydrological Cycle Attributes in Hydrological Years
Based on the monthly precipitation data of Laiwu River hydrological station from 1956 to 2016,the maximum four-month precipitation mainly occurs in the same period of flood season every year,accounting for more than 75%of the annual precipitation,which is the main growth and formation period of surface water and groundwater in the basin.The precipitation in the remaining eight months is less than a quarter of the annual precipitation,which is the decline pe-riod of the attenuation consumption of both surface water and groundwater stored in the basin.The process line of the dif-ference product of the monthly modulus ratio vividly expresses the annual oscillation process of the hydrological annual water cycle,which proves that the hydrological annual water cycle is a more complete annual water cycle process than the calendar year.Through the regression analysis of monthly precipitation runoff,it is concluded that the main influencing factors of monthly runoff in flood season are monthly precipitation and previous monthly precipitation.The main influ-encing factor of monthly runoff in dry season is previous monthly flow.It also proves from one side that the hydrological annual water cycle is a more complete annual hydrological cycle process than the calendar year.Therefore,it is feasible to forecast runoff in December,January and February of each year.It provides a reference for the study of hydrological an-nual water cycle.
Hydrological yearWater cycleMonthly modulus ratio coefficientDifference product process lineRegres-sion analysis