Analysis of the Relationship between Tourist Demand and Sustainable Development Indicators in the Context of the Danube River in the Romanian Trajectory

Practice has shown that tourism is an activity with a global spread, and sustainable development being a concept with global applicability, the intersection of the two elements is considered inevitable. Both elements are commensurable, which makes it possible to study them and analyze the relationships that arise from cohabitation in the economic and social environment. The purpose of this study is to find out to what extent the variation of tourism demand is influenced by the variation of some indicators of sustainable development. A multifactorial regression model was used, in which the number of tourists represents the dependent variable, and the number of unemployed, the natural increase of the population and the existing accommodation capacity are independent variables. For data processing, the Eviews statistical software was used. The greatest impact on the number of tourists is manifested by the existing accommodation capacity, and overall, the variation of the dependent variable is explained in proportion of 83% by the variation of the independent variables.


Introduction
In an age characterized by the technological evolution of economic activities, accelerated industrialization and the effects they have on the environment, the only solution for tourism to maintain its continuity over time is to become sustainable.It is obvious that the presence of tourists in a particular destination can bring both advantages and disadvantages, following the principle that each right corresponds to an obligation.Also, the presence of tourists in a particular destination is generated by a multitude of reasons or, better said, by a multitude of influencing factors.These influencing factors can be classified into several categories, as presented by Minciu (2004, 40-41): factors of influence by their nature, factors of influence by the duration of the action, factors of influence by role, factors of influence by direction of action, determining factors in accordance with the orientation of their influence.
In terms of sustainable development, its influencing factors have economic, environmental or social valences and is measured by different indicator systems, as presented by the European Commission (2016), the United Nations (2007), the National Institute of Statistics ( 2018) and other such institutions.Thus, the purpose of the present research is to find out to what extent the number of tourists is influenced by certain indicators of sustainable development, given the county of Calarasi in Romania.
According to Choi and Turk (2011: 124-129), sustainable indicators that can influence tourism can be part of the six dimensions, namely the economic, social, cultural, environmental, political and technological.In other words, sustainability indicators have a very broad spectrum of action.Starting from the premise that the number of tourists is an indicator that influences different indicators of sustainable development, another research premise can be developed, namely whether sustainable development indicators can influence the number of tourists.The second premise is the one from which this research started.The content of the research consists in presenting the analyzed area, the purpose and objectives, the methodology used, the literature review, results, conclusions and bibliography.

Geographical and economic coordinates of the analyzed area
The Danube River crosses ten countries, namely: Germany, Austria, Slovakia, Hungary, Croatia, Serbia, Romania, Bulgaria, Moldova Republic and Ukraine (Olson and Krug, 2020, p.885).Also, most of the river (30%) is found in Romania (Mazilu, 2011, p.45).Romania is located in the lower basin of the Danube (Țigu, 2012, p.170) and is bordered by the river in the south.The importance of the Danube River for Romania is boundless, as the Danube and its tributaries represent 97.8% of the waters that cross the territory of the country (Țigu, 2012, p.170).The Danube trajectory on the territory of Romania measures 1,075 kilometers, being crossed the following counties: Caraş-Severin, Mehedinţi, Dolj, Olt, Teleorman, Giurgiu, Calarasi, Ialomița, Constanța, Brăila, Galați and Tulcea (Mitrică et al., 2016, p.244).In other words, the Romanian Danube area is composed of the 12 counties that the Danube River crosses.A statistic of two tourist indicators and two very important economic indicators for the 12 Romanian counties bordering the Danube is presented in table 1.
With regard to the table 1, it should not be taken out of context that, in the territory of Constanta County, there are the main tourist resorts on the Romanian Black Sea coast; and in the territory of Tulcea County, there is the Danube Delta.These aspects may influence the statistics shown in table 1.Also, although all these counties have a valuable common point, namely the Danube River, it is noted that the statistics presented in table 1 is heterogeneous.From an economic point of view, Calarasi County is characterized by the following elements: the employed population totals 88,100 people; the main activities of the national economy carried out in Calarasi County, in descending order, are agriculture, industry and construction and services; the unemployment rate is 3.6%; the contribution to the gross domestic product of the county is 0.8%; the main industrial branch is the food and beverage industry (Regional Directorate of Statistics Calarasi, 2021, pp.8-15).
Among the natural tourist resources are included the Danube, with a length of 152 kilometers on the territory of the county, the natural reservations (Șoimul Island, Ciocănești Island, Haralambie Island), the lakes, and deciduous forests.Among the anthropogenic tourist resources are the monastic ensembles (the Church of Plătărești, the Church of Negoiești), the museums, the former Byzantine fortress "Păcuiul lui Soare" (Calarasi County Council, 2015).As a conclusion, it can be admitted that Calarasi County is an agrarian county, which has, as strengths, the agricultural production and the food industry, and whose main touristic resource is represented by the hydrographic network.

Aim and objectives
The purpose of this study is to find out to what extent the variation of tourist demand, expressed by the number of tourists, is influenced by the variation of some indicators of sustainable development, considering a Danube County, more precisely Calarasi County.The objectives of the study include identifying statistically significant indicators of sustainable development, finding out the values that change the tourist demand when increasing by one unit the value of sustainable development indicators, and identifying the sustainable development indicator that has the greatest impact on tourism demand.

Methodology
The data used in the research was taken from the website of the

Review of the Literature
The literature review is particularly important part, as based on it, conceptual clarifications are presented on the analyzed subjects, in this case the tourist demand and the indicators of sustainable development.Also, the literature review includes results of the approaches of other authors regarding the analyzed subjects.

Tourist demand
Like other activities, tourism activity can be measured by specific indicators.One of these indicators is represented by the number of tourists arriving at a particular destination.In a narrow sense, one can equate tourist demand with the number of tourists arriving at a particular destination.The tourist demand is a representative indicator for the touristic circulation, representing the number of tourists at a destination, calculated annually or on shorter time intervals (Turcu and Weisz, 2008, p.10).Globally, the continent of Europe has the highest number of tourists -744 million, followed by Asia and the Pacific -362 million, the Americas -219 million, Africa -70 million and the Middle East -65 million (World Tourism Organization, 2020).The distinction between tourist demand and tourist consumption is very important.
According to Turcu and Weisz (2008, p.23), the tourist demand takes shape within the residence of the tourism consumer i.e., the tourist, and the touristic consumption materializes in the destination where the touristic offer manifests itself.In a general sense and from an economic point of view, the tourist demand or the number of tourists arriving at a certain destination represents, along with the touristic offer, a component of the tourist market.
A more detailed definition of the tourist demand is given by Bălăcescu and Zaharia (2011, p.11) who argue that "the tourist demand represents the number of people who materialize their desire to travel outside their own residence, temporarily and periodically, the reasons being other than the carrying out of paid activities".It is noted that the previous definition is built on the model of the classical definition of tourism, with the mention that there is a visible emphasis on the number of people who carry out the movement.
As mentioned above, the tourist demand, more precisely the number of tourists, is an indicator that can be calculated annually, but also on shorter time intervals, which means that the statistical analyses on this indicator can also be made annually or on shorter time intervals, such as months (Dincu et al., 2016, p.40).Many statistical analyses that take into account this indicator refer to its dynamics and the trends it may have in the future.The importance of analyzing this indicator is also given its economic impact, better said by the relationship between it and various macroeconomic indicators, such as the Gross Domestic Product.Lazar and Pop (2012, p.11) concluded that the elasticity of Gross Domestic Product according to the number of tourists is significant and positive.It is worth noting that not only the number of tourists can influence certain economic indicators, but also the number of tourists can be influenced by certain economic indicators.Gabroveanu, Stan and Radneantu (2009, p.68) showed that, in the first decade of the XXI century, the influence of the consumer price index and the total household incomes had on the number of tourists in Romania was 95% approximately.In other words, between the number of tourists and the different economic indicators, there is a relationship of interdependence.
Also, tourism is not only closely linked to some economic indicators but is also linked to some indicators of sustainable development.If we treat the number of unemployed as an indicator of sustainable development (National Institute of Statistics, 2018), the sustainable link between the number of tourists arriving at a destination and the number of unemployed people at that destination would mean that at an increase in the number of tourists, the number of unemployed to decrease.This is very likely, given that, in general, tourism has the capacity to attract the surplus on the labor market and, implicitly, to reduce unemployment (Minciu, 2004, p.28).Previous statements evoke the prospect of the dependent link between tourism and unemployment, or more precisely between the number of tourists and the number of unemployed, in which the number of unemployed depends on the number of tourists.In other words, there is also the prospect of the inverse dependent link, in which the number of tourists depends on the number of unemployed.
Another element that can be treated as an indicator of sustainable development would be the natural increase of the population (National Institute of Statistics, 2018).From a mathematical point of view, a numerical increase in the population could generate an increase in the number of tourists.More specifically, in the case of economically developed countries, a numerical increase in population could generate an average annual increase in the number of tourists between 0.5% and 1% (Minciu, 2004, p.45).The previous statements present the perspective of the link of dependence between the number of tourists and the natural increase of the population, in which the number of tourists represents the dependent variable.
If the two examples of sustainable development indicators mentioned above are of a more general nature, the existing accommodation capacity (National Institute of Statistics, 2018) is an indicator of sustainable development specific to tourism, as it is also an indicator of quantification of tourism activity.It is clear that the accommodation service, expressed by the accommodation capacity, that is to say, by the number of accommodation places, is indispensable for any stay.The correlation between the number of tourists and the accommodation capacity is a subject treated by many authors, whether it is treated at county level, such as the case of Suceava County (Zaharia, Hapenciuc and Gogonea, 2008) or at the level of the development regions of Romania (Popescu, 2016).In the first case, an increase in the accommodation capacity generates an increase in the number of tourists; and in the second case, an increase in the number of tourists generates an increase in the accommodation capacity.In other words, there is a relationship of interdependence between the number of tourists and the accommodation capacity.
The indicators such as number of unemployed, the natural increase of the population and the capacity of tourist accommodation can also be grouped in terms of resources, in the sense that the number of unemployed affects the statistics of human resources in tourism, the natural increase of the population supports the possible increase of human resources in tourism, and the existing accommodation capacity is an anthropogenic resource indispensable for carrying out tourism activities.Human resources are considered to be the resources "that ensure the functioning of the elements of the tourist offer" (Dedu, 2012, p.122).The series of sustainable development indicators, which could influence local tourism and, implicitly, the number of tourists can continue, for example: the population connected to wastewater depletion stations, the number of passengers travelling by public transport, the average gross monthly salary, climate change through indicators like rainfall (Liu, 2016).It is worth noting that the number of tourists can take the form of a variable dependent on certain economic indicators and indicators of sustainable development, but it can also take the form of an independent variable.Klarin (2018, p.76) found that there are three key elements when discussing sustainable development, namely: development, needs and future generations.These elements are also contained in United Nations definition of sustainable development, "the meeting of one's own needs by all people and the fulfilment of all the aspirations for a better life" (United Nations, 1987, p.24).In other words, sustainable development aims at a balanced improvement of the quality of living.In this context, the consumption-result ratio takes on a particular importance, in the sense that it is desirable that the results of human activities be achieved following a rational and responsible consumption of resources.
Over time, there have not been many studies that have dealt the relationship between tourism and sustainable development, although it has been found that the principles of sustainable development cannot be implemented as tourism specific economic and social activities (Sharpley, 2000, p.14).However, there are also studies that show the capacity of tourism to contribute to the achievement of the objectives of sustainable development, because the tourism industry has one of the strongest impacts worldwide (Robu, David Sobolevschi and Petcu, 2019).Moreover, studies have shown that tourism indicators, such as the occupancy coefficient of accommodation capacity, can be influenced by various indicators of sustainable development such as the Gross Domestic Product per capita, the schooling rate, life expectancy at birth or gas emissions (Popescu et al., 2014), but also the fact that between tourism indicators and sustainable development indicators there can be strong positive or negative relationships (Popescu et al., 2014).
According to the World Tourism Organization (2015), tourism can contribute to supporting all sustainable development goals, but most importantly, it supports the following goals: sustainable and inclusive economic growth, sustainable production and consumption, sustainable use of ocean and marine resources.Tourism is considered to contribute mainly to achieving these goals, as tourism is a great generator of jobs, can promote local tradition and products, and is a viable economic solution for the vast majority of coastal areas.
Regarding the sustainable development indicators, it can be admitted that they can be specific, more precisely they are created based on the characteristics of small areas such as cities or villages (Khalifa and Connelly, 2009, pp.1184-1185) Kirilchuk, Rykunova and Panskov (2018, pp.293-294), who for sustainable development indicators with territorial coverage propose: emissions of greenhouse gases, resources used for energy production, the amount of pollutant emissions, the amount of polluting emissions from large enterprises.
The analysis of tourism sustainability can also be done by calculating the Sustainability Tourism Index (Mitrică et al., 2021).Thus, to calculate this indicator, the indicators of tourism sustainability can be used, such as: anthropic tourist resources, tourist intensity, the population employed in tourism, occupancy rate in accommodation units, the length of the drinking water supply network, the length of the gas supply network, the population density, the number of elderly people compared to the number of young people, road accessibility and percentage of protected areas (Mitrică et al., 2021, p. 6).Based on previous list, it is observed that the indicators of tourism sustainability are very diverse having a tourist and social character.

Tourists and sustainable development
Tourists visiting Romania consider it necessary to implement the principles of sustainable development in society and in the field of tourism, taking into account the following reasons: conservation of resources, reducing the effects of pollution, finding solutions for activities that are not friendly to the environment, ensuring prosperity for future generations (Madar and Neacșu, 2020).In other words, tourists are aware that tourism also has disadvantages, and that sustainable development is the solution to eradicate these disadvantages.
In relation to sustainable development, tourists can be influenced by the extent to which tourism service providers direct their efforts towards sustainable development.Dabija and Băbuț (2013) showed that the biggest influence on tourist satisfaction has the economic dimension of sustainable development, put into practice by hotels.More precisely, the tourist's satisfaction is influenced by the financial situation of the accommodation unit, its investments and its financial stability.Not only the economic dimension, but also the social dimension of sustainable development influences the satisfaction of tourists depending on their type, for example, the satisfaction of cultural tourists, as shown by Asmelash and Kumar (2018).Tourists can relate to some elements of sustainable development depending on the values they believe in.Adongo, Taale and Adam (2018) showed that tourists who believe that man is the center of the universe show an empathic attitude towards nature conservation, and tourists who support economic growth through tourism activities show an empathic attitude towards other tourists and towards the development of the local community.These things reinforce the fact that tourists are aware of the impact that their actions can have on nature, on other tourists and on the local community.Thus, it is necessary for tourists to be followers of sustainable practices.
The importance of tourists is not only revealed by their number but also by the fact that they, through their behavior, can positively or negatively affect the destination they visit.Tourists can acquire environmentally friendly behavior, the environment being the ''key element of the concept of sustainable development'' (Dabija and Băbuț, 2013, p.627) insofar as they have knowledge of the environment show an empathic attitude and are aware of their impact on the environment.This goal can be achieved through informal education (Meschini et al., 2021).At the same time, personal norms are very important in determining the behavior of tourists, for example, regarding the reduction of the amount of waste at the destinations they visit (Wang et al., 2021).Personal norms also positively affect the behavioral intention of tourists to practice a civilized tourism (Liu, An and Jang (Shwan), 2020).Usually, the foundations of these personal norms are laid in the family environment.Further, Szromek, Hysa and Karasek (2019, p.11) showed that tourist of all generations (Baby Boom, X, Y and Z) agree that the adoption of a civilized behavior does not depend on the destination and must be the same both at home and at the destination visited.In some regions of the globe, such as the Arctic, "tourists have the most positive attitude towards sustainable development practices, compared to residents or companies operating in the field of tourism'' (Chen, 2015, p.229).In conclusion, tourists through their behavior are a key factor in implementing sustainable development at the destinations they visit.
Based on the above considerations, it is justified to study the relationship between tourism demand and sustainable development indicators.

Results and Discussions
Due to the fact that the data series used are time series, it is imperative that non-stationary data series be stationary.For this, the ADF -Augumented Dickey-Fuller Test -was applied (Codirlașu, Moinescu and Chidesciuc, 2010, p.24).Thus, the series of the average gross monthly salary and the harvested wood are stationary series as such, and the series of local public passenger transport, the natural increase of the population, the number of unemployed, the population connected to the wastewater depletion stations, the drinking water production capacity, the tourist accommodation capacity and the number of tourists arriving in Calarasi County are stationary series at the first difference.By estimating the regression model between stationary data series, using the ls (least squares) function, an invalid regression model was obtained since the probability of the F-test (0.12) is more than 5%.Moreover, due to the fact that only the probability of the coefficient related to the series the number of unemployed (0.04) is less than 5%, all the variables whose coefficients have a probability of more than 15% have been eliminated.Thus, the analysis still included the number of tourists arriving in Calarasi County, the tourist accommodation capacity, the number of unemployed and the natural increase of the population.Estimating the regression model again, using the ls function, a valid multifactorial regression model was obtained since the probability of the Ftest (0.02) is less than 5%.Thus, the model takes the following form: (1) Where: b0 -the free term of multifactorial regression model b1 -coefficient for the X2 data series (natural increase of population) b2 -coefficient for the X3 data series (number of unemployed persons) b3 -coefficient for the X6 data series (tourist accommodation capacity) ei -model errors.
Additionally, the regression between the number of tourists arriving in Calarasi County, as a dependent variable and the natural increase of the population, the number of unemployed and the tourist accommodation capacity, as independent variables, is not false because Durbin Watson statistic (2.55) is higher than R-squared (0.61).Given that there is no false regression, and the estimated model is valid, it was possible to test the hypotheses of the estimated model.
The VIF -Variance Inflation Factors -method was used to test the multicollinearity hypothesis (Anghelache et al., 2012, p.228).For the data series the tourist accommodation capacity and the natural increase of population, VIF was equal to 1.09, and for the data series the number of unemployed, VIF was equal to 1.07.Since the VIF took values lower than 6, it is admitted that there is no multicollinearity.Therefore, it is not necessary to correct the estimated regression model.
The Breusch-Godfrey test was used to test the hypothesis of lack of autocorrelation of errors (Codirlașu, Moinescu and Chidesciuc, 2010, p.51).Although the probability of the Chi-square statistic (0.02) is less than 5%, the probability of F test (0.055) is higher than 5%.Thus, it is accepted that the errors in the estimated model are self-correlated.Therefore, it is necessary to correct the estimated regression model.The White test was used to test the homoskedasticity hypothesis (Anghelache et al., 2012, p.228).Since the Chi-square statistic and the F test have probabilities higher than 5%, respectively 0.66 and 0.74, it is admitted that the errors are homoscedastic.Therefore, it is not necessary to correct the estimated regression model.The Jarque-Bera test was used to test the hypothesis of normality of errors (Codirlașu, Moinescu and Chidesciuc, 2010, p.30).Since the probability of the Jarque-Bera test (0.65) is higher than 5%, it is accepted that the errors are normally distributed.Therefore, it is not necessary to correct the estimated regression model.
Since the errors are self-correlated, it is necessary to correct the estimated regression model.The Cochrane-Orcutt procedure was used to correct the autocorrelation of the errors and, implicitly, of the estimated regression model (Pagliacci et al., 2015, p.76).Following the Cochrane-Orcutt procedure, the output was obtained as shown in table 4. Because the number of values in the data series is relatively small, the model cannot be used to make forecasts, but summarizes as a whole, the link between tourism demand in Calarasi County and indicators of sustainable development at the territorial level.These results can be interpreted as follows: ▪ At an increase of the existing accommodation capacity with 1 accommodation place, the number of tourists arriving in Calarasi County will increase by 16.60 tourists; ▪ At an increase of the number of unemployed with 1 unemployed person, the number of tourists arriving in Calarasi County will decrease by 0.85 tourists; this can also be explained by the fact that by increasing the number of unemployed there is a possibility that the providers of basic tourist services will be unable to provide service; ▪ At an increase of the natural increase of the population with 1 person, the number of tourists arriving in Calarasi County will increase by 9.13 tourists; this prediction can be explained by the fact that, with the increase in the number of family members, household expenses increase and the family is forced to consolidate their income and a solution would be to open business in tourism, and more specifically for Calarasi County would be agrotourism; ▪ Because R-squared (coefficient of determination) has the value 0.83, it can be admitted that the variation of the number of tourists arriving in Calarasi County is explained in proportion of 83% by the variation of the accommodation capacity, the number of unemployed and the natural increase of the population.
The proposed prediction model could take the following form: number of tourists = intercept + (natural increase of the population x coefficient of natural increase of the population) + (number of unemployed x coefficient of the number of unemployed) + (tourist accommodation capacity x coefficient of tourist accommodation capacity) + errors.(3) The values of the coefficients related to the data series demonstrate that the greatest impact on the number of tourists arriving in Calarasi County is held by the variable entitled existing accommodation capacity, so of an anthropogenic resource.This is followed by the variable entitled natural increase of the population and finally by the variable entitled number of unemployed.

Conclusion and Recommendations
Based on the fact that the statistics of the number of tourists and other economic indicators differ among the 12 counties that make up the Romanian trajectory of the Danube River, it is not excluded that the relationship between the number of tourists and the indicators of sustainable development will differ from one county to another.The statement found in the literature, according to which tourism has the ability to reduce unemployment is also valid for Calarasi County, because an increase in the number of unemployed by 1 unemployed person, the number of tourists will decrease by 0.85 tourists, which means that a decrease in the number of unemployed, the number of tourists will increase.In other words, if the number of tourists visiting the county increase, the number of unemployed in the county will decrease.So, a small number of unemployed people stimulates the increase of the number of tourists arriving in the county.At the same time, this interpretation may or may not be valid for the other counties that make up the Romanian trajectory of the Danube River.Moreover, Romania is not a developed country, but is a developing country.In this sense, the statement that an increase in the number of populations generates an increase in the number of tourists is also valid for Calarasi County, because an increase in natural increase of the population by 1 person, the number of tourists visiting Calarasi County will increase by 9.13 tourists.This interpretation may also be valid or not for the other Danube counties.If the number of unemployed and the natural increase of the population are two indicators with social values, existing accommodation capacity is an indicator specific to tourism and it turned out that, for Calarasi County, this indicator influences more the number of tourists than the first two indicators mentioned above.Existing accommodation capacity generates an increase in the number of tourists visiting Calarasi County by 16.60 tourists.This interpretation may or may not be suitable for the other Danubian counties.
With the exception of unemployment, it turned out that the natural increase of the population and existing accommodation capacity have positive influence on the number of tourists arriving in Calarasi County, and overall, the influence of the three indicators of sustainable development on the number of tourists is 83%.Thus, in order to increase the number of tourists visiting Calarasi County, solutions must be found and stimulated to increase the population and the existing accommodation capacity, but also solutions to reduce unemployment, one of them being to increase the number of tourists, within the sustainability limits of the region concerned.Referring to the themes from which the indicators come, solutions must be found to support and strengthen social cohesion (Kamble and Bouchon, 2016) and public health at local level (Spiegel et al., 2007).
number of tourists arriving in Calarasi County x1 -local public passenger transport (thousands of people) x2 -the natural increase of the population x3 -number of unemployed persons x4 -population connected to wastewater depletion stations x5 -drinking water production capacity (m 3 /day) x6 -tourist accommodation capacity (number of seats) x7 -average gross monthly salary x8 -harvested wood (m 3 ) Sustainable development is a concept that has gained momentum with the awareness and intensification of the negative effects produced by human activities on society and the environment.Like any other concept that has global applicability, sustainable development has a number of principles and indicators of measurement.Also, on the topic of sustainable development, countless conferences and meetings were held aiming at strengthening the implementation of the principles of sustainable development, especially in areas affected by the negative effects of human activities.Among these conferences and meetings can be mentioned the United Nations Conference on Human Environment held in Stockholm in 1972, the Brundtland Report of 1987, the United Nations Conference on Environment and Development held in Rio de Janeiro in 1992, the Johannesburg Summit of 2002 and many other conferences and meetings on sustainable development.Based on these meetings and conferences, and based on the documents issued,

Table 1 :
Economic and touristic characteristics of the Danube counties Source: Website of the National Institute of Statistics (Tempo Online time series, http://statistici.insse.ro:8077/tempo-online/,accessed on 18 September 2021).
National Institute of Statistics.Due to the fact that Calarasi County represents a part of the total area of Romania, respectively, a part of the Romanian Danube trajectory, the sustainable development indicators at territorial level, provided by the National Institute of Statistics, were used.The Romanian Danube area consists of several counties, including Calarasi County.Although it benefits from the same special natural resource, namely the Danube River, Calarasi County, compared to the other Danube counties, registers the lowest number of tourists in most of the years of the analyzed period (National Institute of Statistics, n.d.); and based on this reason, Calarasi County was chosen for this research.Due to the lack of data and the different date ranges, the 2006-2019 timeframe was chosen, as data for most indicators were available for this range.For the same reason, for this research, the indicators of sustainable development chosen were local public passenger transport, the number of unemployed, the natural increase of the population, the average gross monthly salary, the tourist accommodation capacity, the population connected to the wastewater depletion stations, the harvested wood mass and the drinking water production capacity.These indicators represent the independent variables, and the number of tourists arriving in Calarasi County represents the dependent variable, and it was taken from the Tempo Online database of the National Institute of Statistics (National Institute of Statistics, n.d.).

Table 3 :
Sustainable development indicators according to the National Institute of StatisticsAs shown in table 3, most sustainable development indicators at territorial level are grouped in theme 1.It is also noted that only one indicator measuring sustainability has been considered for tourism.In general, the themes and, implicitly, the indicators presented in the previous table fall within the economic dimension, the social dimension or the environmental dimension.The indicators of sustainable development represent in fact, the figures and percentages behind some economic and social realities in a given area, having the ability to influence other elements of the economic and social reality, including tourism.A comprehensive classification of sustainable development indicators is made by 10 Public utility of local interest The length of the streets in the cities.Source: Website of the National Institute of Statistics (https://insse.ro/cms/files/IDDT2012/index_IDDT.htm,2018).

Table 4 :
Estimated model after application of the Cochrane-Orcutt procedure Based on the data in table 4, it is observed that the probability of F test (0.006) is less than 5%.Furthermore, the probabilities are given the tourist accommodation capacity (0.02), the number of unemployed (0.002) and the natural increase of the population (0.008) are less than 5%, which means that the coefficients are statistically significant and that the estimated regression model is valid and can be written as: Y = 974.35+(16.60 x X6)+(-0.85 x X3)+ (9.13 x X2) + ei(2)