| In the Loess Plateau,water is one of the main limiting factors for plant growth,and water in the ecosystem mainly comes from soil moisture input by precipitation.Due to the limitation of climatic conditions,water and soil loss,drought and water shortage and other water resources problems,the utilization rate of natural precipitation in this area is low,and water resources are seriously wasted.In order to investigate the rainwater interception,collection ability,and distribution characteristics of the red plum apricot economic forest on the Loess Plateau after applying the rainfall infiltration and irrigation system,the infiltration characteristics of the red plum apricot root system after natural precipitation passed through the system and to determine the Effective rainfall after applying rainfall-collection infiltration irrigation system.Taking the red plum apricot forest land in Yuanzhou District,Guyuan City,Ningxia as the research object,based on the measured data of natural rainfall combined with the measured data of artificial simulated rainfall,the method of comparative observation was used to analyze the characteristics of small rainfall in Yuanzhou District.Experiment and simulation of apricot rainfall collection and seepage irrigation process.The research achieved the following main results:(1)The interannual change of precipitation in Yuanzhou District of Guyuan City in the past 60 years shows an increasing trend as a whole.The rainfall in the flood season(June to September)accounts for a large proportion of the total annual precipitation,accounting for 72.91%of the annual precipitation.Most of the small rainfall in this area,the total rainfall of 0?l6mm accounted for a large proportion of the total annual rainfall,with an average proportion of 58.53%.The rainfall trend in each stage of 0?16mm increased or decreased.The rainfall of 0?4mm,4?8mm,and 12?16mm showed an increasing trend,and only 8?12mm of rainfall showed a decreasing trend.And the increasing trend of rainfall of 0?4mm and 4?8mm is larger than that of 12?16mm.(2)During the experimental observation period,the natural rainfall was concentrated in the small rainfall interval,and the rainfall below 5mm accounted for 83.3%.The artificial rainfall method used in the study is similar to the rainfall drop with a similarity coefficient of 0.91.The artificial rainfall results are slightly higher,but still have high similarity and applicability.Under the condition of artificial rainfall simulation,the rainfall collection system has a linear relationship with rainfall,and the collection flow increases with the increase of rainfall.(3)During the test period,a total of 16 rainfalls were observed and analyzed.The total rainfall was 80.30mm,of which the collected rainfall was 52.14mm,the infiltration irrigation system interception was 18.19mm,and the canopy interception was 9.97mm,respectively accounting for 64.93%of the total rainfall,22.65%and 12.42%.The average infiltration irrigation system collection rate was 61.29%,the average infiltration irrigation system rejection rate was 27.12%,and the average canopy interception rate was 11.95%.From the fitted equations obtained from the experimental observations,it can be concluded that the catchment increases with the increase of rainfall,and there is a significant linear relationship between the catchment and rainfall(R2=0.9955).The collecting rate gradually increases with the increase of rainfall,but the increasing trend gradually decreases,and there is a logarithmic relationship between the collecting rate and rainfall(R2=0.6939).The rainfall collection rate of small rainfall magnitude rainfall is small and unstable.As the rainfall magnitude increases,the logarithmic relationship of the rainfall collection rate increases and is relatively stable.(4)The infiltration process starts from the water outlet at the bottom of the infiltrator.The main advancement direction of the wet front is 450 downward along the horizontal line.The downward moving speed of the wet front is faster than the horizontal and upward migration rates.Under ideal conditions,the shape of the wet body is almost altar-shaped.The volume of the wet body gradually increases with the increase of rainfall time,and there is a power function relationship between the volume of the wet body and the rainfall time.With the infiltration irrigation system in place,the effective rainfall of the four-year-old red plum apricot is 16.22mm. |
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