| At present,the situation of water resources in China is serious,and the shortage of water resources is becoming an important factor hindering the social and economic development of our country.For agriculture,although the agricultural water use efficiency has improved significantly with the advancement of science and technology and social development,but the problem of water shortage in agriculture is still serious.so the research of the method of agricultural water use,especially the research is very necessary in arid and semi-arid area.Drip irrigation under mulch is a water-saving irrigation technology in recent years has been widely used in water shortage area,it is a technology of drip irrigation and drip irrigation under mulch combined,the implementation of this technology not only can greatly improve the efficiency of irrigation in semi-arid area but also can effectively alleviate the problem of shortage of irrigation water in semi-arid area.However,while drip irrigation under mulch in reducing irrigation water,the plastic film mulching and ridge greatly changed the infiltration and evaporation interface,and have a certain impact on soil water movement,so analysis and Research on plastic film mulching and ridge of rule and action mechanism of the effect of rainfall infiltration and evaluation of extent of rainfall utilization on film mulching,has a practical significance for the rational development and utilization of groundwater resources in the research area.On the one hand,the rainfall infiltration law under three kinds of irrigation methods: drip irrigation under mulch,drip irrigation and surface irrigation were compared and analyzed through the in situ observation experiment,On the other hand the rainfall infiltration model under the surfer irrigation and the drip irrigation under the mulch is established by Hydrus-2D,in addition,some applications are applied to the model,and finally the effect of drip irrigation under mulch in the study area on rainfall infiltration was obtained.In the study,comparative analysis and single factor sensitivity analysis were used.The results of the study are as follows:(1)The change trend of soil water content after each rainfall basically shows an increase and then decrease,and then gradually to a steady trend,Whether it is drip irrigation under mulch,drip irrigation or surface irrigation all are in line with the law;after rainfall the active range of the change of water content is roughly within 50 cm for drip irrigation under mulch and 40 cm for drip irrigation and 60 cm for surface irrigation;from the 0-40 cm shallow soil drip irrigation under mulch water content of change is low compared with surface irrigation,at the same time 0-40 cm shallow soil within the same depth of drip irrigation under mulch the boundary moisture > Moisture content in the ditch> Moisture content in the mulch.(2)The cumulative infiltration relationship under different irrigation mode after each rainfall in observation period show: surface irrigation> drip irrigation> drip irrigation under mulch;cumulative infiltration under three irrigation modes is also increasing with the increase of the cumulative rainfall;surface irrigation in a few days after the end of rainfall the cumulative infiltration reduction degree greater than drip irrigation mulch,showed that the film cover can reduce the surface evaporation,water retention is relatively good;in the same rainfall the relation of infiltration capacity about three different irrigation mode is: surface irrigation> drip irrigation> drip irrigation under mulch.(3)The maximum infiltration depth relationship under different irrigation mode after each rainfall in observation period show: surface irrigation> drip irrigation> drip irrigation under mulch;the maximum infiltration depth of drip irrigation under mulch can reach about 120 cm,the maximum infiltration depth of drip irrigation can reach about 140 cm,the maximum infiltration depth of surface irrigation can reach about 160 cm.(4)Use hydrus-2D to establish the drip irrigation under mulch and surface irrigation rainfall infiltration models has a relatively good fitting effect;the application of Hydrus-2D model results show that the initial water content and rainfall intensity have a certain impact on the process of rainfall infiltration,when the rainfall intensity is fixed the initial water content is lower,the greater the moisture variation before and after the rainfall,the lower the rainfall intensity is when the initial moisture content is fixed,and the the greater the moisture variation before and after the rainfall,under the same conditions of surface irrigation change degree in the overall moisture content greater than drip irrigation under mulch;increase the initial water content or rainfall intensity will decrease the cumulative rainfall infiltration. |
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