Water pricing following rainfall distribution and its implications for irrigation agriculture

This study uses data from water auctions, conducted by the traditional irrigation community of Vélez Blanco. Water prices are comprehensively compared and statically correlated with local precipitation data on different temporal scales; the data analyzed reach back to 1967. The local prevailing Mediterranean climate is characterized by a mean annual precipitation amount of 419 mm, while effective rainfall (≥1 mm) occurs averagely at 37 days per year. The rainfall distribution data used were of daily, seasonal and annual resolution and are assessed on their influence on the local water price formation. The results were validated with information about local agricultural practices and subjective perceptions of the vega's status, gained from interviews with local farmers. Results show that high correlation coefficients are achieved when water prices and precipitation data are correlated on a monthly scale. The highest correlation coefficients are achieved with a temporal offset of one month throughout the spring and summer season. Interestingly, neither short term water surplus, nor long term water deficit (consecutive drought years) are clearly reflected. Based on the given data-base, annual rainfall distribution has proven to be a significant factor that influences water price formation in the Vega of Vélez Blanco.