بررسي تغييرات نفوذ عمقي در قسمت هاي مختلف كرت هاي شاليزاري

چكيده انگليسي :

Investigation of Infiltration Variation in Different Sections of Paddy Fields Forough Kamyab Talesh Forough kamyab@gmail com 2009 01 21 Department of Water Engineering Isfahan University of Technology Isfaha 84156 83111 IranDegree M Sc Language FarsiSeyed Farhad Mousavi mousavi@cc iut ac irAbstractRice is the major crop in paddy fields of Guilan province The area under rice cultivation in Guilan is 205269ha about 35 8 of total paddies in Iran Irrigation method in paddy fields is basin type with permanentflooding One of the important parameters in determination of rice water requirement is infiltration of water tothe soil Deep percolation is the main factor in application efficiency of a paddy field Since the surfacerunoffs from paddy fields are used again for irrigation of downstream fields irrigation losses are limited todeep percolation If infiltration is estimated accurately rice water requirement is evaluated better and designof irrigation and drainage systems and necessary structures is done properly The amount of water infiltrationis measured often in the center of a field without considering the differences in the position of points especially points near the field boundaries In this research spatial variation of soil water infiltration wasstudied in different soil textures In each texture in longitudinal and transverse directions points withdistance from the boundary of 0 5 2 5 6 5 12 5 m the last point was center of the paddy basin withthree replications 0 5 to 1 m on sides of the main direction were selected and time variation of infiltrationrate was measured In each spot soil bulk density and penetration resistance was also measured Infiltrationwas measured by quick method bulk density by metal cylinders 7 7 cm diameter and 4 1 cm height andpenetration resistance by penetrometer The results of final infiltration rates showed that this parameter hasdifferent values at different locations of the paddy basin In clay silty clay and loam soils average finalinfiltration rates in longitudinal and transverse directions are higher than the center of the basin For example in clay texture average final infiltration rates in longitudinal and transverse directions were 0 174 and 0 134cm day respectively and in the middle of the basin was 0 126 cm day For loam texture the results wereopposite As was expected because of uneven puddling in different parts of the paddy field the infiltrationrates were different Infiltration rate of near border points was more than the center of the basin This showsimproper puddling of the soil near the boundaries The results also showed that bulk density varies with soildepth and the differences are significant at 5 probability level For example in silty clay soil bulk densitiesof the first to third layers were 0 829 0 927 and 1 014 g cm3 In this soil average bulk densities inlongitudinal and transverse directions were 1 003 and 0 996 g cm3 The results showed that in all the soiltextures there was significant difference between the penetration resistance of points Comparison of finalinfiltration rate with bulk density and penetration resistance showed that infiltration rate has no relationshipwith bulk density but has negative relationship with penetration resistance In loam texture this relationshipwas not observed The conclusion of this research is that if measured soil physical properties in paddy fieldsare going to be representative of the whole filed they should be measured at different locations especiallynear the borders Key Word Infiltration Paddy field Rice Puddling Texture

كامياب طالش، فروغ

بررسي تغييرات نفوذ عمقي در قسمت هاي مختلف كرت هاي شاليزاري

شبكه هاي آبياري گيلان , برنج