برآورد ارزش اقتصادی مطبوعیت زیست‌محیطی پارک کوهستانی صُفه اصفهان (رهیافت هزینه سفر فردی آشکارشده و اظهارشده)

Introduction: Natural resources and the environment, such as mountains are considered public goods. The main features of these public goods are lack of market and price for exchange. This issue leads to a worthless impression about these goods, lack of effort for their conservation and preventing resource degradation. One of the major benefits of environmental resources, such as mountains, is their function as environmental amenities (for leisure and recreation). The estimation of their recreational worth is important as a part of the total value of such resources. In this context, the aim of this study is to estimate the economic value of environmental amenities of Sofeh Highland Park in Isfahan by individual travel cost method.
Materials and Methods: Travel cost method is used for the evaluation of public goods or environmental non-market commodities. It is applied to a wide range of areas, including tourism values of lakes and wetlands, coral reefs, biodiversity and national parks, recreational fishing and mountaineering. The travel cost approach does not ask willingness to pay directly, but imputes it from the observed behavior of other visitors through an estimated demand function, which relates the number of observed trips to the incurred travel cost. Underpinning the travel cost method is for the estimation of the recreational demand function, from which consumer surplus estimates can be derived. Consumer surplus -the measure of non-market benefits to the visitors- is the difference between what the visitor would be (theoretically) willing to pay to go the intended recreational location, and what they are actually required to pay. In this research, the individual travel cost method was used. For this purpose, a 290 item questionnaire with simple random sampling was filled by travelers in the area in 2013. Then the demand function of environmental amenities (tourism demand) was estimated in two scenarios by using negative binomial regression for the revealed and the expressed travel costs and total travel costs.
Results Discussion: Collected data shows that the average age of visitors is 31 years. Most of them are young, 66% of visitors are male and the rest are female. Most of the respondents chose the spring season for visiting Sofeh Park. Results of negative binomial regression estimation showed that age, income, distance and the revealed and total travel cost have a significant effect on the total number of visits in both scenarios. Age and income coefficients are positive. Thus, these variables have a direct effect on the number of visit in both scenarios. But distance and travel cost coefficients are negative. Therefore, these variables have a reverse effect on the total number of visits in both scenarios. These results confirm the demand law. The law of demand states that the quantity demanded and the price of a commodity are inversely related. Travel cost as commodity price for tourism demand function in the first scenario is only revealed -travel- cost of trip to location and in the second scenario is the revealed cost in addition to the opportunity cost of trip to the recreational location. Consumer surplus as the average value of environmental amenities is calculated by1/ , where is the coefficient related to travel cost variable in the tourism demand functions. Also, the average value of environmental amenities for anyone visit in the first and the second scenarios are 797 and 1145 thousand Rials, respectively. The obvious difference between recreational values in the two scenarios is due to opportunity cost. The total recreational value of the Sofeh Highland Park equals to the product of number of annual visits and average recreational value. Finally the total value of annual visits to the park, in the above scenarios is more than 11952 and 17174 billion Rials, respectively.
Conclusion: In this study, the value of environmental amenities of the Sofeh Highland Park were estimated. Notice that the above values are not the price of Sofeh Park that is a natural environment in the current study. In fact, these values are "minimum of recreational values" of any given environment. It is essential for the visitors to have knowledge of this value in order to conserve the environment and the regional facilities. Furthermore, it is essential for the authorities to have knowledge of this value, with the aim of making more efforts and overseeing improvements and conservation of this environment. Also, alongside the protection plans for Sofeh Highland Park, authorities can bring about an increase in the number of annual visits to this Park by reducing travel and opportunity costs through facilitating the conditions to access, such as improving public transportation to this park.

Keywords: Individual Travel Costs, Isfahan Sofeh Highland Park, Negative Binomial Regression, Value of Environmental Amenities, Tourism Demand Function