ﺑﺮرﺳﯽ ﺗﻐﯿﯿﺮات ﺿﺮاﯾﺐ ﻣﻌﺎدﻻت ﻧﻔﻮذ و اﻣﮑﺎن ﮐﺎرﺑﺮد آن ﻫﺎ در رﻃﻮﺑﺖﻫﺎ و ﭼﮕﺎﻟﯽﻫﺎي ﻣﺨﺘﻠﻒ

Investigating the Changes of Coefficients of Infiltration Equations and Their Functional Evaluation under Various Soil Moisture and Bulk Densities

ﻧﻔﻮذ ﯾﮏ ﻓﺮآﯾﻨﺪ ﮐﻠﯿﺪي اﺳﺖ ﮐﻪ در ﺑﺮﻧﺎﻣﻪ رﯾﺰي، ﻃﺮاﺣﯽ، ﻣﺪﯾﺮﯾﺖ و ﺑﻬﯿﻨﻪ ﺳﺎزي ﺳﯿﺴﺘﻢﻫﺎي آﺑﯿﺎري ﻣﻮرداﺳﺘﻔﺎده ﻗﺮار ﻣﯽﮔﯿﺮد؛ ﺑﻨﺎﺑﺮاﯾﻦ اﻧﺘﺨﺎب ﯾـﮏ ﻣﺪل ﻧﻔﻮذ ﻣﻨﺎﺳﺐ در ﺑﻬﯿﻨﻪ ﺳﺎزي ﻣﺼﺮف آب در ﮐﺸﺎورزي و ﺑﺮرﺳﯽ ﭼﺮﺧﻪ آب در ﻣﻘﯿﺎس ﮐﻮﭼﮏ و ﺑﺰرگ ﺿﺮوري اﺳﺖ. ﻫﺪف از اﯾـﻦ ﭘـﮋوﻫﺶ ﺑﺮرﺳـﯽ ﺗﻐﯿﯿﺮات ﺿﺮاﯾﺐ ﻣﻌﺎدﻻت ﻧﻔﻮذ ﮐﺎﺳﺘﯿﺎﮐﻒ، ﮐﺎﺳﺘﯿﺎﮐﻒ-ﻟﻮﯾﯿﺲ و ﻫﻮرﺗﻦ ﻧﺴﺒﺖ ﺑﻪ ﺗﻐﯿﯿﺮ ﻫﻢ زﻣﺎن رﻃﻮﺑﺖ اوﻟﯿﻪ و ﭼﮕﺎﻟﯽ ﻇﺎﻫﺮي ﺧﺎك و ﺗﺄﺛﯿﺮ آن ﺑﺮ ﻋﻤﻠﮑﺮد ﻣﻌﺎدﻻت ﻧﻔﻮذ در ﺧﺎك ﻫﺎي ﻣﺨﺘﻠﻒ ﺑﻮد. ﺑﺮاي اﯾﻦ ﻣﻨﻈﻮر داده ﻫﺎي ﻧﻔﻮذ ﺗﺠﻤﻌﯽ در ﻫﺸﺖ ﺑﺎﻓﺖ ﺧﺎك، ﺳﻪ ﭼﮕﺎﻟﯽ ﻇﺎﻫﺮي ﺷﺎﻣﻞ 1/4 ،1/3 و 1/5 ﮔﺮم ﺑـﺮ ﺳﺎﻧﺘﯽﻣﺘﺮ ﻣﮑﻌﺐ و ﭘﻨﺞ ﺳﻄﺢ رﻃﻮﺑﺖ ﺣﺠﻤﯽ 0/25 ،0/2 ،0/15 ،0/1 و 0/3 ﺑﺎ اﺳﺘﻔﺎده از HYDRUS-1D ﺗﻬﯿﻪ ﮔﺮدﯾﺪ. ﺑﻪ ﻣﻨﻈـﻮر ﺑﯿـﺎن ﺗـﺄﺛﯿﺮ ﺗﻐﯿﯿـﺮات ﺿﺮاﯾﺐ ﻣﻌﺎدﻻت ﻧﻔﻮذ ﺑﺮ ﮐﺎراﯾﯽ آن ﻣﻌﺎدﻻت در رﻃﻮﺑﺖ ﻫﺎ و ﭼﮕﺎﻟﯽ ﻫﺎي ﻣﺨﺘﻠﻒ، اﺑﺘﺪا ﺿﺮاﯾﺐ ﻣﻌﺎدﻻت ﺑﺮاي ﻫﻤﻪ ﺳﺮيﻫﺎي ﻧﻔﻮذ ﺗﺠﻤﻌﯽ ﻣﺤﺎﺳﺒﻪ )ﻣﺮﺣﻠﻪ ﺑﺮازش( و در ﻣﺮﺣﻠﻪ ﺑﻌﺪ در ﯾﮏ رﻃﻮﺑﺖ و ﭼﮕﺎﻟﯽ ﻣﺸﺨﺺ ﺑﺮاي ﻫﺮ ﺧﺎك ﻣﺤﺎﺳﺒﻪ و ﺑﺮاي رﻃﻮﺑﺖﻫﺎ و ﭼﮕﺎﻟﯽ ﻫﺎي دﯾﮕﺮ ﻣﻮرداﺳﺘﻔﺎده ﻗﺮار ﮔﺮﻓﺖ )ﻣﺮﺣﻠـﻪ ارزﯾﺎﺑﯽ(. ﺑﺮ اﺳﺎس ﻧﺘﺎﯾﺞ ﺣﺴﺎﺳﯿﺖ ﺿﺮاﯾﺐ ﻣﻌﺎدﻻت ﻧﻔﻮذ ﻧﺴﺒﺖ ﺑﻪ ﺗﻐﯿﯿﺮات رﻃﻮﺑﺖ و ﭼﮕﺎﻟﯽ ﻇﺎﻫﺮي از زﯾﺎد ﺑﻪ ﮐﻢ ﺑﻪ ﺗﺮﺗﯿﺐ ﺿـﺮﯾﺐ ﻣﻌﺎدﻟـﻪ ﮐﺎﺳـﺘﯿﺎﮐﻒ )ak(، ﺿﺮﯾﺐ ﻣﻌﺎدﻟﻪ ﮐﺎﺳﺘﯿﺎﮐﻒ-ﻟﻮﺋﯿﺲ )akl(، ﺗﻮان ﻣﻌﺎدﻟﻪ ﮐﺎﺳﺘﯿﺎﮐﻒ )bk(، ﺿﺮﯾﺐ ﻣﻌﺎدﻟﻪ ﻫﻮرﺗﻦ )bh( و ﺗﻮان ﻣﻌﺎدﻟﻪ ﮐﺎﺳﺘﯿﺎﮐﻒ-ﻟﻮﺋﯿﺲ )bkl( ﺑﻪ دﺳﺖ آﻣﺪ. ﻣﯿﺎﻧﮕﯿﻦ اﻓﺰاﯾﺶ RMSE ﻣﻌﺎدﻟﻪ ﮐﺎﺳﺘﯿﺎﮐﻒ، ﮐﺎﺳﺘﯿﺎﮐﻒ-ﻟﻮﯾﯿﺲ و ﻫﻮرﺗﻦ در ﻣﺮﺣﻠﻪ ارزﯾﺎﺑﯽ ﺑﻪ ﺗﺮﺗﯿﺐ 34 ،3/25 و 2/8 ﺑﺮاﺑﺮ ﻣﺮﺣﻠﻪ ﺑﺮازش ﺑﻪ دﺳـﺖ آﻣﺪ؛ ﺑﻨﺎﺑﺮاﯾﻦ ﮐﻤﺘﺮﯾﻦ ﺣﺴﺎﺳﯿﺖ در ﻋﻤﻠﮑﺮد ﻣﻌﺎدﻟﻪ ﻫﻮرﺗﻦ و ﺑﯿﺸﺘﺮﯾﻦ ﺣﺴﺎﺳﯿﺖ در ﻣﻌﺎدﻟﻪ ﮐﺎﺳﺘﯿﺎﮐﻒ-ﻟﻮﺋﯿﺲ رخ داده اﺳﺖ.

Infiltration is a key process which can be considered for scheduling, design, management and optimization of irrigation systems. Therefore, it is necessary to choose an appropriate infiltration model to optimize water consumption in agriculture and to study the water cycle on a small and large scale. The purpose of this study was to investigate the sensitivity of the coefficients of Kostiakov, Kostiakov-Lewis and Horton infiltration equations to the simultaneous changes of initial moisture and soil bulk density and its effect on the performance of infiltration equations in different soils. For this purpose, cumulative infiltration data in eight soil textures, three bulk densities including 1.3, 1.4 and 1.5 g / cm3 and five volumetric moisture levels including 0.1, 0.15, 0.2, 0.25 and 0.3 was prepared using HYDRUS-1D. In order to represent the effect of the sensitivity of the coefficients of infiltration equations on the efficiency of those equations at different moisture and bulk densities, first the coefficients of the equations are calculated for all infiltration data (fitting step) and then at a specific moisture and bulk density for each soil, the coefficients are calculated and for other moistures and densities were used (evaluation step). Based on the results, sensitivity of the coefficients of infiltration equations with changes of moisture and bulk density from high to low was obtained the coefficient of the Kostiakov equation (ak), the coefficient of the Kostiakov-Lewis equation (akl), the power of the Kostiakov equation (bk), the coefficient of the Horton equation (bh) an‎d the power of the Kostiakov-Lewis equation (bkl), respectively. The mean increase of RMSE of the Kostiakov, Kostiakov-Lewis and Horton equations in the evaluation stage was respectively 3.25, 34 and 2.8 times the fitting stage. Therefore, the lowest and the highest sensitivity occurred in the Horton and the Kostiakov-Lewis equations respectively.