ﺑﺮرﺳﯽ روش ﻫﺎي ﻣﺨﺘﻠﻒ ﺗﺨﻤﯿﻦ ﻧﯿﺎزآب زﯾﺴﺖ ﻣﺤﯿﻄﯽ(ﻣﻄﺎﻟﻌﻪ ﻣﻮردي: رودﺧﺎﻧﻪ اﻟﻨﺪﭼﺎي)

Investigating Different Methods for Estimating the Need for Environmental Water (Case Study: Alandchay River)

زﻣﯿﻨﻪ و ﻫﺪف: ﻃﺮح ﻫﺎي ﺗﻮﺳﻌﻪ ﻣﻨﺎﺑﻊ آب داراي اﺛﺮات زﯾﺴﺖ ﻣﺤﯿﻄﯽ ﻣﺘﻌﺪدي ﻣﯽ ﺑﺎﺷﺪﮐﻪ ﺗﻐﯿﯿﺮ رژﯾﻢ ﻃﺒﯿﻌﯽ رودﺧﺎﻧـﻪ و ﮐـﺎﻫﺶ ﺟﺮﯾـﺎن ﺳﻄﺤﯽ ﭘﺎﯾﯿﻦ دﺳﺖ از ﻣﻬﻢ ﺗﺮﯾﻦ آن اﺳﺖ. ﺑﺮآورد ﺟﺮﯾﺎن زﯾﺴﺖ ﻣﺤﯿﻄﯽ ﻣﻮرد ﻧﯿﺎز ﺑﺮاي ﺳﻼﻣﺖ رودﺧﺎﻧﻪ ﻫﺎ و اﮐﻮﺳﯿﺴﺘﻢ ﻫﺎي آﺑﯽ ﭘﺎﯾﯿﻦ دﺳـﺖ از اﻫﻤﯿﺖ وﯾﮋه اي ﺑﺮﺧﻮردار اﺳﺖ. راﻫﮑﺎر ﭘﺎﯾﺪار، ﺗﺠﺪﯾﺪﻧﻈﺮ در ﺗﺨﺼﯿﺺ آب ﺑﺮاي ﻣﺼﺎرف ﻣﺨﺘﻠﻒ و اﻓﺰاﯾﺶ ﺳﻬﻢ ﺟﺮﯾـﺎن زﯾﺴـﺖ ﻣﺤﯿﻄـﯽ از 10%ﮐﻨـﻮﻧﯽ ﺑـﻪ 20 ﺗـﺎ 40% آورد ﺳـﺎﻟﯿﺎﻧﻪ رودﺧﺎﻧــﻪ ﻫـﺎ اﺳـﺖ. ﻫـﺪف اﯾــﻦﭘـﮋوﻫﺶ، ارزﯾـﺎﺑﯽ ﺗﻮزﯾـﻊ ﻣﺎﻫﯿﺎﻧــﻪ ﺟﺮﯾـﺎن زﯾﺴـﺖ ﻣﺤﯿﻄـﯽ ﯾــﮏ رودﺧﺎﻧﻪﺷﺎﺧﺺﺑﺎﺟﺮﯾﺎنداﺋﻤﯽ )رودﺧﺎﻧﻪ اﻟﻨﺪﭼﺎي( از روش ﻫﺎي ﻣﻮﺟﻮد ﻫﯿﺪرواﮐﻮﻟﻮژﯾﮑﯽﺑﻮده اﺳﺖ-4 FDC ﺷﺎﺧﺺ ﻫﺎي ﺗﺪاوم ﺟﺮﯾﺎن -3 Tessman -2؛ Tennant -1 :روش ﺑﺮرﺳﯽ در اﯾﻦ ﻣﻘﺎﻟﻪ، از ﻫﻔﺖ روش ﻫﯿﺪرواﮐﻮﻟﻮژﯾﮑﯽ DRM -6 FDC shifting -5 Smakhtin و 7- روش ﮐﯿﻔﯿﺖ آب ﻣﻮﺳﻮم ﺑﻪ راﺑﻄﻪ Q( اﺳﺘﻔﺎده ﺷﺪه اﺳﺖ. ﻧﺘﺎﯾﺞ ﺑﺮآورد ﺟﺮﯾﺎن زﯾﺴﺖ ﻣﺤﯿﻄﯽ رودﺧﺎﻧﻪ اﻟﻨﺪﭼﺎي در ﺳﺎل 97 از روش ﻫﺎي ﻣﺨﺘﻠﻒ ﻣﺤﺎﺳﺒﻪ ﮔﺮدﯾﺪ. ﯾﺎﻓﺘﻪ ﻫﺎ: ﺑﺮ اﺳﺎس اﯾﻦ ﻣﻘﺎﻟﻪ، ﺣﻘﺎﺑﻪ زﯾﺴﺖ ﻣﺤﯿﻄﯽ رودﺧﺎﻧﻪ اﻟﻨﺪ ﭼﺎي در روش FDC shifting و ﺑﺎ ﭘﺬﯾﺮش ﺷﺮاﯾﻂ رودﺧﺎﻧﻪ در ﺣﺪاﻗﻞ وﺿﻌﯿﺖ اﮐﻮﻟﻮژﯾﮑﯽ ﻗﺎﺑﻞ ﻗﺒﻮل )ﮐﻼس ﻣﺪﯾﺮﯾﺖ زﯾﺴﺖ ﻣﺤﯿﻄﯽ C(، در اﯾﺴﺘﮕﺎه ﻫﯿﺪروﻣﺘﺮي ﺑﺪﻻن، ﺷﺪت ﺟﺮﯾﺎن ﻣﺘﻮﺳﻂ ﺳﺎﻟﯿﺎﻧﻪ ﻣﻌﺎدل 1/56 ﻣﺘﺮﻣﮑﻌﺐ ﺑﺮ ﺛﺎﻧﯿﻪ ﺑﺮآورد ﮔﺮدﯾﺪ ﮐﻪ از ﻧﻈﺮ ﻣﻘﺪار دﺑﯽ ﺣﻘﺎﺑﻪ زﯾﺴﺖ ﻣﺤﯿﻄﯽ از ﺗﻤﺎم روش ﻫﺎي ﻫﻔﺖ ﮔﺎﻧﻪ ﻣﺤﺎﺳﺒﻪ ﺷﺪه ﺑﯿﺶ ﺗﺮﯾﻦ ﻣﻘﺪار را ﺑﻪ ﺧﻮد اﺧﺘﺼﺎص داده و روش Tennant ﻫﻢ در اﯾﺴﺘﮕﺎه ﻧﺎﻣﺒﺮده 0/39 ﻣﺤﺎﺳﺒﻪ ﮔﺮدﯾﺪ. ﺑﻘﯿﻪ روش ﻫﺎ ﺑﯿﻦ دو روش ﯾﺎدﺷﺪه ﻗﺮار ﮔﺮﻓﺘﻪ اﺳﺖ. ﺑﺤﺚ و ﻧﺘﯿﺠﻪ ﮔﯿﺮي: ﻧﺘﺎﯾﺞ ﻣﻘﺎﻟﻪ ﺣﺎﺿﺮ دﻗﺖ روش FDC shiftingرا ﺑﺎ ﮐﻼس زﯾﺴﺖ ﻣﺤﯿﻄﯽ C ﮐﻪ در اﯾﺴﺘﮕﺎه ﻣﻮرد ﻣﻄﺎﻟﻌﻪ ﺑﺮاﺑﺮ ﺑﺎ 1/56 ﻣﺘﺮﻣﮑﻌﺐ در ﺛﺎﻧﯿﻪ اﺳﺖ، ﺑﻪ ﻋﻨﻮان ﮐﻼس ﻣﺪﯾﺮﯾﺖ زﯾﺴﺘﯽ ﺑﺮاي رودﺧﺎﻧﻪ اﻟﻨﺪﭼﺎي ﻧﺸﺎن ﻣﯽ دﻫﺪ. اﯾﻦ ﻧﺘﺎﯾﺞ ﻧﺸﺎن ﻣﯽ دﻫﺪ ﮐﻪ روش ﻫﺎي ﺳﺮﯾﻊ ﻣﺤﺎﺳﺒﻪ ﺟﺮﯾﺎن زﯾﺴﺖ ﻣﺤﯿﻄﯽ ﺑﮑﺎر رﻓﺘﻪ در اﯾﺮان، ﻋﻤﺪﺗﺎً ﺑﺪون در ﻧﻈﺮ ﮔﺮﻓﺘﻦ ﺷﺮاﯾﻂ زﯾﺴﺖ ﻣﺤﯿﻄﯽ اﯾﺮان ﺑﮑﺎر ﺑﺮده ﻣﯽ ﺷﻮد. اﯾﻦ اﻣﺮ دﻗﺖ ﻧﺘﺎﯾﺞ ﺣﺎﺻﻞ را ﺑﺸﺪت ﮐﺎﻫﺶ داده وﮔﺎه ﺣﺘﯽ ﻧﺘﺎﯾﺞ ﻣﻌﮑﻮﺳﯽ را ﺣﺎﺻﻞ ﻣﯽ ﮐﻨﺪ.

Background and Objective: Water resource development plans have several environmental impacts, the most important of which are natural river flow change and downstream surface reduction of flow. Estimation of the environmental flow required for the health of rivers and downstream ecosystems are of particular important. A sustainable strategy is a revision of the allocation of water for various uses and an increase in the share of the environmental flow from the current 10% to (20-40%) annual yields of rivers. The main objective of this study was to evaluate the monthly distribution of the environmental flow of an indicating river with a permanent flow (Alandachay river) using existing hydro-ecological methods. Method: In this paper, seven hydro-ecological methods were used: (1- Tennant; 2- Tessman; FDC 4- Smakhtin 5- FDC shifting 6-DRM; 7- Water-quality method called Q-relation). The results of environmental estimation of Alandachay River were calculated using different methods. Findings: According to this paper, the environmental law of the Alandachay river in the FDC shifting method and with acceptance of the river conditions at the minimum ecological status acceptable (environmental management class C), at hydrometry station, average annual flow rate was estimated to be 1.56 cubic meters per second, which considering the amount of environmental water, the highest calculated amount of all seven methods and was calculated 0.39 by using Tennant method. The other remaining methods were between these methods. Discussion and Conclusion: The results of this paper show the accuracy of the FDC shifting method with the environmental class C at the studied station at 1.56 cubic meters per second as the bio-management class. These results show that quick methods of calculating the environmental flow used in Iran are mainly applied without considering the environmental conditions. This greatly reduces the accuracy of the results and even yields the opposite results.