Water supply to a mountain village (Drave, North Portugal): historical overview, current scenario, and future perspectives

Abstract

Throughout the world, mountain populations have developed specific agroecosystems, with different types of water supply for irrigation and domestic use. The Drave mountain village (North Portugal) has, for centuries, faced harsh hydrological, hydrogeological, and hydropedological conditions. Since the second half of the twentieth century, the nature of water demand in Drave has drastically changed. The research objective is to understand the evolution of water demand and supply in the village of Drave, from the sixteenth century to the present day, and to present a possible solution to meet future water needs. A sampling network, comprising surface water and groundwater points, was established. Then, a sampling campaign took place in the dry season, and another one in the wet season. Laboratory analysis encompassed major inorganic ions, Potentially Toxic Elements, and microbiological parameters. Groundwater vulnerability to pollution was assessed through the DRASTIC index and GVTool, a Geographic Information System open-source application. Two historical periods were identified concerning the Drave water demand and supply: (i) from the foundation of the village until the second half of the twentieth century; (ii) from the mid-twentieth century on. The current scenario consists of using water resources with chemical and microbiological contamination to supply the needs of temporary inhabitants. Groundwater vulnerability to pollution ranges from extremely low to moderately low, with the most vulnerable areas corresponding to valley bottoms. A possible solution to meet the future water demand consists of abstracting and treating only surface water during the wet season and taking advantage of the hydrological regime of stream alluvial deposits during the dry season.