Valoração Económica do serviço de fornecimento de água de rega do Regadio de Chókwè: uma aplicação do método da Valoração contingente

Abstract

The economic valuation of environmental resources and the services related to their supply is important because it produces economic instruments that can be used in the design of sustainable environmental management plans, policies and strategies. However, despite the great importance that Valoração has and, looking specifically at freshwater in Mozambique, where, according to Farolfi et al. (2011) about 87% of the total fresh water consumed in Mozambique is used in agriculture, there are very few documentary studies on this resource. Thus, the present research aimed to economically value the water supply service for agricultural use in the Chókwè irrigation system. For this, an inductive research was developed in the form of a field study using the contingent Valuation method. To obtain the data, a form was applied to a sample of 150 statistically determined and randomly selected farmers. The collected data were econometrically analyzed by the logit and tobit models in one and two stages to determine the probabilistic and monetary availability of farmers to pay for the irrigation water supply service as well as in the identification of its determinants. However, the average economic values ​​found in the survey were 0.77 (0.03 USD / m 3) and 2.23 (0.09 USD / m 3) MT / m 3, corresponding to a probability of acceptance by farmers of about 42% and 19% for the cold and hot season respectively. In this case, looking at the average cost of operating and maintaining irrigation systems in 13 African countries, in the order of 0.02 USD / m 3, estimated by FAO (2004), it can be said that the average values ​​of this research are applicable for the perimeter irrigated in Chókwè as they would guarantee the sustainability of this service and the consequent adoption of measures to rationalize the use of irrigation water by farmers. In turn, the median economic values ​​found were 0.50 MT / m 3 (0.02 USD / m 3) for the cold season with an acceptance probability of around 50% and 0.48MT / m 3 (0.02 USD / m 3) for hot season with a probability of acceptance of 34%. In this case, both the economic values ​​estimated in the present research as well as the average cost of maintenance and irrigation operation estimated by FAO (2004) are above those currently applied in the irrigated perimeter of Chókwè, where taking as an example the rice culture with a consumption effective in the hot season of approximately 7689 m 3 / ha per cycle, it would be talking about a value of about 0.1040 MT / m 3 (0.0034 USD / m 3). With this it can be said that the values ​​currently charged for the supply of water in the irrigated perimeter of Chókwè do not guarantee the sustainability of this service. It was also found that the amount charged for irrigation water supply to farmers negatively determines the probabilistic availability for both the cold and hot seasons. The monetary availability to be paid (monetary DAP) for the cold season is positively influenced by the number of workers and the training that farmers have in the agricultural area and, negatively by the area cultivated by each farmer. In the hot season, this monetary DAP is positively influenced by the purpose of production and negatively by the area planted by each farmer in the irrigated area. As a way of contributing to local development, it is recommended to create water management plans, policies and strategies that prioritize the allocation and use of water for small farmers in the irrigated perimeter of Chókwè. Similar studies are also recommended with a view to ascertaining the real costs of operating and maintaining these irrigation systems. (TRADUÇÃO NOSSA)