The Experimental Study On Characteristics About The Transport Of Water And Nitrogen In Multi-point Source Intersection Of Muddy Water Film Hole Irrigat Ion

Based on the review of relevant literatures at home and abroad,combined with the characteristics of water quality in the Yellow River Basin,this paper studies the characteristics of the transport of water and nitrogen in multi-point source infiltration of muddy water film hole irrigation by laboratory test multi-point source infiltration experiment and theoretical analysis,and effects of various influencing factors on the infiltration capacity of the film irrigation?the wetting front migration distance?the moisture distribution in the wet body and the distribution of soil NO3--N multi-point source infiltration The main research results are as follows:(1)By studying the characteristics of water and nitrogen transport in the multi-point source of water and fertilizer,the mathematical model of multi-point source infiltration of water and fertilizer was established.The distribution of water content?the distance of wetting front movement and soil NO3--N content in the center of the wetting body of muddy water and fertilizer infiltration from multi-point sources.The results show that t The cumulative infiltration amount per unit membrane pore area and infiltration time of muddy water film hole irrigation with multi-point source of fertilizer at each stage conformed to Kostiakov infiltration model,and the wetting front migration distance of membrane pore center,intersection center and intersection surface was power function,logarithm function and binary function respectively.The distribution of water content in wetting body was as follows:membrane pore center>interspecific intersection center>interspecific intersection center>intersection center>4 point source intersection center;The concentration of NO3--N was the highest at the intersection center of four point sources,followed by the center of membrane hole,and there was no significant difference in the content of NO3--N between interspecific intersection centers and interspecific intersection centers.(2)The Kostiakov infiltration model fits the relationship between the cumulative infiltration per unit membrane pore area and infiltration time of muddy water film pore irrigation with different fertilizer concentration,membrane pore diameter and muddy water sediment concentration.The cumulative infiltration per unit membrane pore area increases with the increase of fertilizer concentration,and decreases with the increase of membrane pore diameter and muddy water sediment concentration.An empirical model of cumulative infiltration per unit membrane pore area,infiltration time and various influencing factors for muddy water film hole irrigation with multi-point source confluence infiltration was established.(3)All the influencing factors have obvious influence on the distance of wetting front migration of muddy water film hole irrigation fertilizer solution at the intersection of multi-point sources.Membrane pore diameter,fertilizer concentration and sediment content of muddy water vary in a certain range.The vertical wetting front of muddy water and fertilizer at different intersection centers under the infiltration mode of muddy water and fertilizer multi-point sources has different function relationship with time.There is a power function relationship between the center of membrane hole and infiltration time;the fitting results between the intersection center and infiltration time are logarithmic functions;and the intersection center and infiltration time are logarithmic functions.The wetting front formed by the free infiltration surface and the multidirectional intersection surface along the horizontal direction of infiltration in the wetted body shows power function and logarithmic function relations with the infiltration time,respectively.Finally,the functional relationship between the distance of wetting front migration in all directions and the influencing factors and infiltration time is established.(4)Infiltration is influenced by various factors,and the distribution of NO3--N content in wetted body is quite different after infiltration;the concentration of NO3--N in the area near the control of the center of membrane hole is higher when muddy water and fertilizer intersect,and then decreases gradually with the increase of soil depth;but at the end of infiltration,the content of NO3--N decreases gradually.The content of NO3--N at the wetting front will accumulate to some extent.The larger the diameter of membrane hole and the concentration of fertilizer solution,the smaller the sediment concentration in muddy water,the more the distribution of NO3--N content in the same position of wetting body.