Valutazione economica delle risorse idriche: il lago Trasimeno

This work aims to investigate the foundations and methodological tools for assessing the economics of natural resources in order to preserve value over time and services they provide to the biosphere and economic development. The focus is in particular the evaluation and control of water resources, using as a case study of the Lake Trasimeno and its watershed. Consequence of the absence of a market is the inability to establish a price on environmental resources to reflect their economic value and can be used to express in monetary terms, the changes in those resources determined by the activities of production and consumption. There are basically two ways to measure the demand for environmental goods: also known as indirect methods of revealed preference, also called direct methods and stated preference. Indirect methods are based on analyzing the relationship between the environmental good under consideration and the private property connected with it. Direct methods are based, essentially, in making disclose to consumers, through interviews and questionnaires, their preferences with regard to environmental goods and services. The research has developed three different models used in particular for the economic valuation: contingent valuation, the travel costs and tradable permits. The three methods allows us to analyze the resource lake from three different viewpoints which together are able to provide a comprehensive assessment of the criticality of the lake system: the contingent valuation was used to determine the value of the Lake and its environmental quality by residents, the travel cost was used to quantify the value by tourists, the simulation of the market for tradable permits is the economic value of the lake for the production system in the basin. The first part of the thesis is focused on tradable pollution. This work is specifically intended to assess their applicability to water resources in a country like Italy. The idea underlying the system of pollution permits is to artificially create a market for environmental goods (in our case water) that do not have and that, because of the lack of a price, are subject to exploitation excessive, the so-called “tragedy of the commons”. In particular we have focused on the phase of initial allocation of permits. The application of PN showed in the past as an instrument of environmental policy has been transformed into a means of altering the structure of the market, reducing their competitiveness to the detriment of consumers. There are basically two ways to allocate permits, grandfathering and auction systems. The grandfathering provides for an initial allocation free of charge where the permits are given on the basis of historical levels of pollution. The auction is instead an allocation for consideration where the economic agents participating in an auction to win permission. In this work we simulated the first assignment using both systems. For the auction system, however, was organized a simulation of a uniform price auction in which economic agents were directly involved in the Lake Trasimeno. From information on the price of permits and the quantity demanded measured with the rod in a sealed envelope was then constructed a simulation model of the so-called dynamic auction clock auction, in which the issuing agency acts as a “Walrasian auctioneer”. The model simulates the price adjustments until you reach the equality between demand and supply of permits. The work done so far allows us to analyze and critically evaluate the different methods depending on allocative efficiency and effectiveness of the instrument of environmental policy and the possibility of creation of the market permits. In addition, we made simulations provide an economic assessment of resource production system for the lake basin of Lake Trasimeno. As mentioned the price of tradable permits is nothing more than the economic value of water resources for the economic sector. In the second part, we have developed the method of the Contingent Valuation. This method of evaluation allows us to quantify the total economic value of resources received by residents of Lake in the towns of the Lake Trasimeno. Our goal is to define the use value and non-use by analyzing the demand for lake. In particular, we wanted to assess three different types of improvement: quality and quantity of water resources, quality of natural areas around the lake are characterized by recreational vocation. This was achieved through the implementation of three distinct models. For this work we used the format based on an elicitation of probabilistic Close Ended. Willingness to pay is a proxy of value in use of the lake and the value of non-use of the lake that is the existence value of water resources. Contingent valuation is a survey technique in which a questionnaire is prepared and administered to a sample of residents in the site in order to reveal quantitative information on the socio-economic characteristics, perceptions, habits and preferences in terms of willingness to pay. You have chosen to make a sample survey “on site” by administering a questionnaire to a sample of residents, submitted in the form of interview to maximize the likelihood of response and quality of the answers themselves, as well as to reduce the time and cost. Data processing for the estimation of willingness to pay requires the use of appropriate statistical models to analyze dichotomous choices, namely the choice between YES (Y = 1) and NO (Y = 0) as a response to willingness to pay a certain figure / bid proposal during the interview. In particular in 3 distinct models have been used logit models, estimated by maximum likelihood estimation. It was conducted for each of the models, the selection of explanatory variables through the procedure "stepwise" which allows the identification of each model in a more discriminating set of variables, able to maximize the level of “accuracy” (% of answers correctly classified) of the model. To test the significance level of each factor included in the model and its ability to explain changes in the dependent variable was subsequently performed a special test of hypotheses on the coefficients selected. Finally, the third part of the study was implemented at the Travel Cost Method This methodology was used to quantify the value of recreational use of the resource Lake. The basic hypothesis is that the number of visits made to a natural resource is a function the cost of travel expenses, time spent to reach the site and visit it and the ticket. Among the various approaches used has been chosen as the Individual Travel Cost observing the behaviour of individual users in the choice of the number of visits to be carried in a certain period of time. The Travel Cost Survey is a technique in which the questionnaire is administered to a sample of visitors to a recreation site in order to reveal quantitative information on the place of origin, socio-economic, frequency of visits, perceptions, and duration associated costs. You have chosen to make a sample survey “on site” by administering a questionnaire to a sample of visitors in the form of interview to maximize the probability of response and quality of the answers themselves, as well as reduce the time and cost. To develop the methodology adopted was a model event count (Count models). In particular, the Poisson process has been adopted is characterized by a discrete nature of the dependent variable and gives the probability of the discrete v (the number of trips). The model was estimated using the maximum likelihood estimate of the vector of parameters of the equation. He then proceeded to the selection of the explanatory variables through a procedure “stepwise” which allows the identification of a more discriminating set of variables that are chosen based on their ability to minimize the deviance of the model. To test the significance level of each factor included in the model and its ability to explain changes in the dependent variable was then carried out an appropriate hypothesis test on the coefficients. Identified the demand curve for the whole recreational experience we have quantified the consumer surplus that represents the gain is the difference between psychology and the willingness to pay (the price that the visitor would be willing to pay for each amount of good that make up a good-service) and the market price of the visitor pays for a certain amount.