ارزيابي كارايي مدل‌هاي تجربي در برآورد رسوبدهي آبخيزهاي كوچك مناطق نيمه خشك با استفاده از داده‌هاي اندازه‌گيري شده

Evaluation of Emprical Models for Sediment Yield Prediction at Semi-Arid Small Watershed using Measured Data

زﻣﯿﻨﻪ و ﻫﺪف: ﺑﺎ ﺗﻮﺟﻪ ﺑﻪ ﻧﺒﻮد اﯾﺴﺘﮕﺎه ﻫﺎي رﺳﻮب ﺳﻨﺠﯽ در اﮐﺜﺮ ﺣﻮﺿﻪ ﻫﺎي آﺑﺨﯿﺰ ﮐﺸﻮر و ﻋﺪم ﮐﻔﺎﯾﺖ داده ﻫﺎ، ﻣﺪل ﻫﺎي ﺗﺠﺮﺑﯽ ﻣﺎﻧﻨﺪ اﺑﺰارﻫﺎي ﻣﻨﺎﺳﺒﯽ ﺑﺮاي ﺗﺨﻤﯿﻦ رﺳﻮﺑﺪﻫﯽ آﺑﺨﯿﺰﻫﺎ ﻣﯽ ﺑﺎﺷﻨﺪ. از آن ﺟﺎ ﮐﻪ اﯾﻦ ﻣﺪل ﻫﺎ در ﺧﺎرج از اﯾﺮان ﻃﺮاﺣﯽ ﺷﺪه، ﻻزم اﺳﺖ ﮐﻪ ﮐﺎرآﯾﯽ آن ﻫﺎ در ﮐﺸﻮر ﺑﺮرﺳﯽ ﺷﻮد. ﻣﻄﺎﻟﻌﺎت ﭘﺮاﮐﻨﺪه اي در ﺧﺼﻮص ﺑﺮآورد ﻓﺮﺳﺎﯾﺶ و رﺳﻮب ﺑﺎ اﺳﺘﻔﺎده از اﯾﻦ ﻣﺪل ﻫﺎ در اﯾﺮان ﺻﻮرت ﮔﺮﻓﺘﻪ و اﮐﺜﺮ اﯾﻦ ﻣﻄﺎﻟﻌﺎت ﺑﻪ واﺳﻄﻪ ﻓﻘﺪان داده ﻫﺎي رﺳﻮب ﻣﺸﺎﻫﺪاﺗﯽ، ارزﯾﺎﺑﯽ ﻣﻨﺎﺳﺒﯽ از اﯾﻦ ﻣﺪل ﻫﺎ ﺑﻪ دﺳﺖ ﻧﻤﯽ دﻫﻨﺪ. ﻟﺬا ﺑﺮاي ﺗﻮﺳﻌﻪ اﯾﻦ ﻣﺪل ﻫﺎ اﺳﺘﻔﺎده از داده ﻫﺎي اﻧﺪازه ﮔﯿﺮي ﺷﺪه، ﺿﺮوري اﺳﺖ. روش ﺑﺮرﺳﯽ: در اﯾﻦ ﺗﺤﻘﯿﻖ، ﭼﻬﺎر ﺑﻨﺪ ﺧﺎﮐﯽ ﮐﻮﭼﮏ در ﺣﻮﺿﻪ ﺳﺪ ﮐﺎرده و ﭘﻨﺞ زﯾﺮﺣﻮﺿﻪ داراي ﺣﻮﺿﭽﻪ ﺟﻤﻊ آوري رواﻧﺎب و رﺳﻮب در ﺣﻮﺿﻪ ﺳﻨﮕﺎﻧﻪ ﮐﻼت اﻧﺘﺨﺎب ﺷﺪ. ﻣﻘﺪار رﺳﻮب ﺗﻪ ﻧﺸﯿﻦ ﺷﺪه در ﻣﺨﺎزن ﺳﺪﻫﺎ ﺑﺎ اﺳﺘﻔﺎده از ﻧﻘﺸﻪ ﺑﺮداري ﺑﻪ دﺳﺖ آﻣﺪ. وزن ﻣﺨﺼﻮص ﻇﺎﻫﺮي رﺳﻮب ﺑﺎ ﻋﻤﻠﯿﺎت ﺻﺤﺮاﯾﯽ ﺗﻌﯿﯿﻦ و ﺣﺠﻢ رﺳﻮب ﻫﺎ ﺑﺎ در ﻧﻈﺮ ﮔﺮﻓﺘﻦ ﺳﺎل ﻫﺎي رﺳﻮب ﮔﯿﺮي ﺑﻪ وزن ﺗﺒﺪﯾﻞ ﺷﺪ. در زﯾﺮﺣﻮﺿﻪ ﻫﺎي ﺳﻨﮕﺎﻧﻪ ﻧﯿﺰ ﭘﺲ از ﻫﺮ ﺑﺎرﻧﺪﮔﯽ ﻣﯿﺰان ﻫﺪررﻓﺖ ﺧﺎك اﻧﺪازه ﮔﯿﺮي ﺷﺪ. در ﻧﻬﺎﯾﺖ ﻣﻘﺪار رﺳﻮب ﺗﻮﺳﻂ ﻣﺪل ﻫﺎي EPM و FSM ﺗﺨﻤﯿﻦ زده ﺷﺪ و ﺑﺎ ﻣﻘﺎدﯾﺮ ﻣﺸﺎﻫﺪه اي ﻣﻘﺎﯾﺴﻪ ﺷﺪ. ﯾﺎﻓﺘﻪ ﻫﺎ: ﻧﺘﺎﯾﺞ ﻧﺸﺎن داد ﺑﺎ ﺗﻮﺟﻪ ﺑﻪ اﺧﺘﻼف زﯾﺎد ﻣﻘﺎدﯾﺮ ﺑﺮآوردي ﻣﺪل FSM و رﺳﻮب ﻣﺸﺎﻫﺪه اي، ﺿﺮاﯾﺐ ﻣﺪل ﺑﺮاي ﺣﻮﺿﻪ ﻫﺎي ﻣﻮرد ﻣﻄﺎﻟﻌﻪ ﻧﯿﺎز ﺑﻪ اﺻﻼح دارد. در ﻧﻬﺎﯾﺖ ﻣﻘﺎدﯾﺮ ﺿﺮﯾﺐ ﮐﺎراﯾﯽ ﻧﺶ-ﺳﺎﺗﮑﻠﯿﻒ ﺑﺮاي ﻣﺪل EPM و FSM ﺑﻪ ﺗﺮﺗﯿﺐ 0/66 و 0/65 ﺑﻪ دﺳﺖ آﻣﺪ. ﺑﺤﺚ و ﻧﺘﯿﺠﻪ ﮔﯿﺮي: ﻧﺘﺎﯾﺞ ﺣﺎﺻﻞ دﻻﻟﺖ ﺑﺮ ﮐﺎراﯾﯽ ﻣﺪل ﻫﺎي ﻣﺬﮐﻮر در ﺑﺮآورد رﺳﻮب ﺣﻮﺿﻪ ﻫﺎي آﺑﺨﯿﺰ ﮐﻮﭼﮏ ﻣﻮرد ﻣﻄﺎﻟﻌﻪ دارد.

Background and Objective: Due to the lack of sediment stations in most of the country's watersheds outlets and inadequacy of data, experimental models can be important tools for the production of these information layers. Common Empirical model in Iran is EPM. Method: Since this model has been designed in other countries, it is necessary to examine its performance in Iran. The main objective of the project is Model situations with nature and complete database available about erosion and its affecting factors. In implementing this plan, 4 small soil dams in Kardeh Dam and five sub-basins have a pond to collect runoff and sediment in Sanganeh of Kalat was selected. These catchment areas were studied and information layers for EPM model produced. Amounts of sediment were estimated and were compared with observed sediment. Findings: The results indicated that the uncalibrated FMS model overestimated the eroded materials. Results of the EPM and calibrated FMS model indicated 0.66 and 0.35 Nash-Sutcliff efficiency. Discussion and Conclusion: Therefore, we can accept the estimated results of this model as somewhat reliable.