ﺑﺮرﺳﯽ ﮐﺎراﯾﯽ ﻣﺪل ﻫﺎي ﺗﺠﺮﺑﯽ STJ-EROS ،SEDMODL2 و WARSEM در ﺑﺮآورد ﻣﯿﺰان ﺗﺤﻮﯾﻞ رﺳﻮب ﺟﺎده ﻫﺎي ﺟﻨﮕﻠﯽ (ﻣﻄﺎﻟﻌﻪ ﻣﻮردي: ﻃﺮح ﺟﻨﮕﻞ داري دﮐﺘﺮ ﺑﻬﺮام ﻧﯿﺎ)

Investigating the performance of the empirical models of SEDMODL2, STJ-EROS and WARSEM in estimating sediment yield from forest roads with different standards

ﺳﺎﺑﻘﻪ و ﻫﺪف: ﺟﺎدهﻫﺎي ﺟﻨﮕﻠﯽ ﯾﮑﯽ از ﻣﻨﺎﺑﻊ ﺑﺎﻟﻘﻮه ﺗﻮﻟﯿﺪ رﺳﻮب در ﺣﻮزهﻫﺎي آﺑﺨﯿﺰ ﺟﻨﮕﻠﯽ ﺷﻨﺎﺧﺘﻪ ﻣﯽﺷﻮﻧﺪ. ﻣﺪل ﻫﺎي ﺑﺮآورد رﺳﻮب اﺑﺰاري ﻣﻘﺮونﺑﻪﺻﺮﻓﻪ و ﺳﺮﯾﻊ در ﺑﺮآورد ﻧﺮخ رﺳﻮبدﻫﯽ ﺟﺎدهﻫﺎي ﺟﻨﮕﻠﯽ ﻫﺴﺘﻨﺪ. ﻫﺮﭼﻨﺪ ﮐﻪ ﮐﺎرآﻣﺪي و دﻗﺖ اﯾﻦ ﻣﺪلﻫﺎ ﻫﻨﻮز ﺑﻪﻃﻮر دﻗﯿﻖ ﺑﺮاي ﺟﺎدهﻫﺎي ﺟﻨﮕﻠﯽ ﺷﻤﺎل اﯾﺮان ﻣﻮرد ارزﯾﺎﺑﯽ ﻗﺮار ﻧﮕﺮﻓﺘﻪ اﺳﺖ. ﺑﻨﺎﺑﺮاﯾﻦ ﻫﺪف از ﭘﮋوﻫﺶ ﺣﺎﺿﺮ ﺑﺮرﺳﯽ و ﻣﻘﺎﯾﺴﻪ ﮐﺎراﯾﯽ ﻣﺪلﻫﺎي ﺗﺠﺮﺑﯽ در ﺑﺮآورد ﻣﯿﺰان ﺗﺤﻮﯾﻞ رﺳﻮب ﺟﺎده ﻫﺎي ﺟﻨﮕﻠﯽ و ﻫﻢ ﭼﻨﯿﻦ ﺑﺮرﺳﯽ ﺗﺄﺛﯿﺮ ﺳﻄﺢ اﺳﺘﺎﻧﺪارد ﻓﻨﯽ راه ﺑﺮ ﻣﻘﺪار ﺗﺤﻮﯾﻞ رﺳﻮب ﺟﺎدهﻫﺎي ﺟﻨﮕﻠﯽ اﺳﺖ. ﻣﻮاد و روشﻫﺎ: در ﺟﺎدهﻫﺎي ﺟﻨﮕﻠﯽ ﻃﺮح ﺟﻨﮕﻞداري دﮐﺘﺮ ﺑﻬﺮامﻧﯿﺎ، 30 ﻗﻄﻌﻪ ﻣﻨﺎﺳﺐ از ﻧﻈﺮ اﻣﮑﺎن ﻧﺼﺐ ﺗﻠﻪ رﺳﻮب ﮔﯿﺮ، ﻣﺸﺨﺺ ﺷﺪ. اﯾﻦ ﻗﻄﻌﺎت ﺑﺎ ﺗﻮﺟﻪ ﺑﻪ ﻣﺸﺨﺼﺎت ﻓﻨﯽ ﺷﺎﻣﻞ ﺷﯿﺐ ﻃﻮﻟﯽ، ﻣﯿﺎﻧﮕﯿﻦ ﺧﺎك ﻟﺨﺖ ﺳﻄﺢ ﺟﺎده، ﻣﯿﺎﻧﮕﯿﻦ ﺧﺎك ﻟﺨﺖ ﺟﻮي، ﻣﯿﺎﻧﮕﯿﻦ ﺧﺎك ﻟﺨﺖ ﺷﯿﺮواﻧﯽ، ﻓﺎﺻﻠﻪ ﺳﺮﭼﺸﻤﻪ رواﻧﺎب ﺗﺎ آﺑﺮو، ﺷﺪت ﺗﺮاﻓﯿﮏ، وﺿﻌﯿﺖ روﺳﺎزي، ﻃﻮل ﺷﯿﺮواﻧﯽ ﺧﺎك ﺑﺮداري، ﺷﯿﺐ ﺷﯿﺮواﻧﯽ ﺧﺎك ﺑﺮداري، ﻋﺮض روﺳﺎزي، ﻋﻤﻖ ﺟﻮي ﮐﻨﺎري، ﻋﺮض ﺟﻮي ﮐﻨﺎري، ﻧﻮع ﭘﻮﺷﺶ ﮐﻒ ﺟﻮي و درﺻﺪ ﺗﺎج ﭘﻮﺷﺶ در ﺳﻪ ﮐﻼﺳﻪ اﺳﺘﺎﻧﺪارد ﭘﺎﯾﯿﻦ، ﻣﺘﻮﺳﻂ و اﺳﺘﺎﻧﺪارد ﺑﺎﻻ ﻃﺒﻘﻪﺑﻨﺪي ﺷﺪﻧﺪ. ﻣﯿﺰان ﺗﺤﻮﯾﻞ رﺳﻮب ﻗﻄﻌﺎت ﭘﺲ از ﻫﺮ 16 ﺑﺎر وﻗﻮع ﺑﺎرﻧﺪﮔﯽ )از ﻓﺮوردﯾﻦ ﻣﺎه ﺗﺎ ﭘﺎﯾﺎن اﺳﻔﻨﺪ( از ﻃﺮﯾﻖ ﺗﻠﻪ ﮔﺬاري در اﻧﺘﻬﺎي ﻫﺮ ﻗﻄﻌﻪ ﻣﻮرد اﻧﺪازهﮔﯿﺮي ﻗﺮار ﮔﺮﻓﺖ. ﺳﭙﺲ ﻣﻘﺪار ﺗﺤﻮﯾﻞ رﺳﻮب ﻗﻄﻌﺎت از ﻃﺮﯾﻖ ﻣﺪل ﻫﺎي STJ-EROS ،SEDMODL2 و WARSEM ﻧﯿﺰ ﺑﺮآورد و ﺑﺎ ﻣﻘﺪار واﻗﻌﯽ ﻣﻘﺎﯾﺴﻪ ﺷﺪ. ﯾﺎﻓﺘﻪ ﻫﺎ: ﻧﺘﺎﯾﺞ ﻧﺸﺎن داد ﮐﻪ ﻣﻘﺪار رس، ﻓﺎﺻﻠﻪ ﺳﺮﭼﺸﻤﻪ رواﻧﺎب ﺗﺎ آﺑﺮو، ﻣﻘﺪار ﺳﯿﻠﺖ، ﻧﻮع ﭘﻮﺷﺶ ﮐﻒ ﺟﻮي، ﻣﯿﺎﻧﮕﯿﻦ ﺧﺎك ﻟﺨﺖ ﺷﯿﺮواﻧﯽ، ﮐﯿﻔﯿﺖ روﯾﻪ ﺟﺎده و ﺷﺪت ﺗﺮاﻓﯿﮏ ﺑﻪﺗﺮﺗﯿﺐ ﻣﻬﻢ ﺗﺮﯾﻦ ﻋﻮاﻣﻞ ﺗﺄﺛﯿﺮﮔﺬار ﺑﺮ ﻣﯿﺰان ﺗﺤﻮﯾﻞ ﺳﺎﻻﻧﻪ رﺳﻮب از ﺟﺎدهﻫﺎ ﻫﺴﺘﻨﺪ. ﻣﻘﺪار ﺗﺤﻮﯾﻞ ﺳﺎﻻﻧﻪ رﺳﻮب از ﺟﺎدهﻫﺎﯾﯽ ﮐﻪ اﺳﺘﺎﻧﺪارد ﭘﺎﯾﯿﻦ دارﻧﺪ )0/35 ﺗﻦ در ﺳﺎل( ﺑﻪﻃﻮر ﻣﻌﻨﯽداري ﺑﯿﺶ ﺗﺮ از ﺟﺎدهﻫﺎي اﺳﺘﺎﻧﺪارد ﻣﺘﻮﺳﻂ )0/24 ﺗﻦ در ﺳﺎل( و اﺳﺘﺎﻧﺪارد ﺑﺎﻻ )0/27 ﺗﻦ در ﺳﺎل( ﺑﻮد. ﻣﻘﺪار واﻗﻌﯽ رﺳﻮب ﺗﻮﻟﯿﺪﺷﺪه از ﻗﻄﻌﺎت ﺟﺎده )0/27 ﺗﻦ در ﺳﺎل( ﺑﻪﻃﻮر ﻗﺎﺑﻞ ﻣﻼﺣﻈﻪ اي ﮐﻢ ﺗﺮ از ﻣﻘﺪار ﺑﺮآورد ﺷﺪه ﺗﻮﺳﻂ ﻣﺪلﻫﺎي SEDMODL2 )1/74 ﺗﻦ در ﺳﺎل(، STJ-EROS )1/32 ﺗﻦ در ﺳﺎل( و WARSEM )1/58 ﺗﻦ در ﺳﺎل( ﺑﻮد. ﺑﺮرﺳﯽﻫﺎي آﻣﺎري ﻧﺸﺎن داد ﮐﻪ ﻓﻘﻂ در ﻣﻮرد ﺟﺎدهﻫﺎي ﺑﺎ اﺳﺘﺎﻧﺪارد ﭘﺎﯾﯿﻦ ﺗﻔﺎوت ﻣﻌﻨﯽداري ﺑﯿﻦ ﻣﻘﺪار واﻗﻌﯽ رﺳﻮب و ﻣﻘﺪار ﺑﺮآورد ﺷﺪه ﺗﻮﺳﻂ ﻣﺪلﻫﺎ وﺟﻮد ﻧﺪاﺷﺖ. ﻧﺘﯿﺠﻪ ﮔﯿﺮي: از ﯾﺎﻓﺘﻪﻫﺎي اﯾﻦ ﭘﮋوﻫﺶ ﻣﯽﺗﻮان ﭼﻨﯿﻦ ﻧﺘﯿﺠﻪﮔﯿﺮي ﮐﺮد ﮐﻪ ﻫﯿﭻﯾﮏ از ﻣﺪلﻫﺎي ﺗﺠﺮﺑﯽ ﻣﻮردﺑﺮرﺳﯽ ﻗﺎدر ﻧﺒﻮدﻧﺪ ﻣﯿﺰان ﺗﺤﻮﯾﻞ ﺳﺎﻻﻧﻪ رﺳﻮب ﺟﺎدهﻫﺎي ﺟﻨﮕﻠﯽ ﻣﻨﻄﻘﻪ ﻣﻮردﻣﻄﺎﻟﻌﻪ را ﺑﺎ دﻗﺖ ﻗﺎﺑﻞ ﻗﺒﻮل ﺑﺮآورد ﻧﻤﺎﯾﻨﺪ و ﻫﻤﮕﯽ ﻣﻘﺪار رﺳﻮب را ﺑﺴﯿﺎر ﺑﯿﺶ ﺗﺮ از واﻗﻌﯿﺖ ﻣﯿﺪاﻧﯽ ﺗﺨﻤﯿﻦ زدﻧﺪ؛ ﺑﻨﺎﺑﺮاﯾﻦ ﭘﯿﺸﻨﻬﺎد ﻣﯽﺷﻮد ﺿﻤﻦ ﺑﺮرﺳﯽ ﻣﺪلﻫﺎي دﯾﮕﺮ ﻧﺴﺒﺖ ﺑﻪ ﺑﻮﻣﯽ ﺳﺎزي ﻣﺪلﻫﺎ ﺑﺮ ﺣﺴﺐ ﺷﺮاﯾﻂ ﻣﻨﻄﻘﻪاي اﻗﺪام ﺷﻮد

Background and Objectives: Forest roads are recognized as potential source of sediment production in forest watersheds. The aims of this research were to determine the performance of the empirical models in estimating sediment yield from forest roads and investigate the effect of technical standards of road on sediment yield. Materials and Methods: In the forest roads of Bahramnia forestry plan, 30 segments which were suitable for sediment trap installation were determined. These segments were classified into low standard, standard and high standard segments based on some technical characteristics Such as average longitudinal slope, percentage of cutslope coverage, distance from runoff source to nearest reputation, traffic density, pavement condition, etc . Sediment yield from segments were measured after each rainfall event (from March 2019 to February 2020) with the use of trapping at the end of each segment. The location of the trap was at the lowest point and adjacent to the reputation Inside each trap, 5 graduated indicators were installed to repeat the measurements. After each rainfall, sediment height (meters) and sedimentation area (square meters) were measured to calculate sediment volume. At the end of the year, three samples were prepared with the help of cylinders from each sediment trap to measure the apparent specific gravity of the sediment.Then estimated sediment yield by SEDMODL2, STJ-EROS and WARSEM was compared with real field values. Findings: Results indicated the amount of clay, distance of runoff to culvert, amount of silt, ditch cover, bare soil on cutslope, road surface quality and traffic volume were respectively effective factors in sediment yield from roads. Annual sediment yield from roads with low standard (0.35 ton per year) was significantly more than standard roads (0.24 ton per year) and high standard roads (0.27 ton per year). The measured sediment yield from road segments (0.27 ton per year) was considerably less than estimated values by SEDMODL2 (1.74 ton per year), STJ-EROS (1.32 ton per year) and WARSEM (1.58 ton per year) models. Statistical analysis showed that only in roads with low standards there wasn’t significant difference between measured values and estimated values by models. Conclusions: From the results of present study it can be concluded that none of models can estimate the annual sediment yield from forest roads of study area and all of them shows values more than real measured values. It is suggested that other models were evaluated and localized according to local properties