Preface

Groundwater stored transiently in aquifers is, by far, the most abundant and widespread source of liquid freshwater on the planet. Its importance to societies is attested by the facts that worldwide about 50% of the public water supply, 40% of irrigation and 35% of industrial uses rely on groundwater. Rivers maintain a baseflow between sparse rainfall events in the basin because groundwater discharges invisibly and continuously to those water bodies that are often incorrectly considered as examples of surface waters originated by overland and run-off flows. Ecosystems dependent on groundwater constitute important repositories of biodiversity, areas of carbon sequestration and food production and have a significant role in local climate. Groundwater plays a determinant role in many engineering interactions with the subsurface, in seawater intrusion and in geothermal energy use, and a sink of energy needed for pumping water from underground. Groundwater is also an important part of climate change adaptation process and is often a solution for people without access to safe water. The quality of groundwater, natural of affected by pollution, has considerable impacts on human and crop health. Natural springs, besides being the most ancient direct access to groundwater, traditionally valued also by the quality of water, normal or mineral with attributes in health treatment, is also a symbol of purity that cultures and religions cherish and protect. However, when freshwater resources come forward, mostly rivers, lakes and artificial reservoirs are mentioned, forgetting groundwater that, by its nature, is a mostly hidden component of the water cycle. In general, groundwater keeps being a disregarded subject by citizens, decision-makers and even scientists, other professionals and the citizens in some way related to water resources, ignoring its interlinkage and essential roles in the water cycle, the ecosystems and the functioning of society. Insufficient knowledge motivates a lack of proportional and responsible actions. This may be at the source of the threats to groundwater despite the importance of the economic, ecological, geological, health and cultural services it provides. As a consequence, and at their peculiar rhythms, the quantity and the quality of groundwater change due to intensive and inappropriate anthropogenic actions coupled to stresses coming from the natural dynamics of the Earth, climate change, population growth and patterning and health, economic development and also an insufficient investment in knowledge, public awareness, proper governance and management at all levels, from global to local. Meanwhile, there are aquifers that remain untapped in regions or periods of water scarcity. Hydrogeology is an established geoscience that studies the occurrence, movement and quality of groundwater as a basis for understanding this essential natural resource as a component of the water cycle and in the society, providing the scientific support for the management of its diverse environmental and anthropogenic uses. Geoethics is an emerging scientific field that deals with the ethical, social and cultural implications of geosciences knowledge, research, practice, education and communication, and with the relevant social role and responsibility of geo-professionals in conducting their activities while interacting with the Earth systems, where groundwater is one of its undisputed important components. Besides, the landmark publications related to the geoethics through the languages of the world and sharing ethical principles through cultural diversity are an inspirational backbone aiming the scientific and technical integrity and culturally diverse approaches