The sustainable Earth screened through the lens of catchment water services

Water has shaped the Earth’s surface into catchments that support a diversity of ecosystem services, such as water and nutrient cycling, soil formation and habitat. Besides supporting, catchments regulate services like flood attenuation and water quality improvements through organism-mediated chemical processes. Catchments are also the geosphere where the water is stored in lakes, wetlands, reservoirs or underground, to be later provided as service to the economic activities such as agriculture or industry, as well as to the humans as drinking water. Finally, catchments may incorporate unique landscapes that leverage recreational and cultural services targeting tourism and social well-being. But catchments are also the geographical domain where humans and meteorological agents dynamize ecosystem services though land use changes and climate shifts. Consequently, catchments are disturbed through amplified soil erosion, water balance reconfigurations, etc., and eventually adapt overtime, either evolving towards a pre-disturbance condition or towards new landscapes. Disturbance and adaption are research questions in the spotlight, with growing published literature on the subject. Thus, a review focused on the latest findings (last couple of years) is worth of consideration and was the motivation to write this opinion paper. While gathering relevant papers from the Science Direct, Web of Science and Scopus databases, we realized that current research essentially shows how disturbance and natural feedbacks of catchments challenge the sustainable physical Earth by shaking support, regulation and provision hydrologic services. Thus, using the PRISMA methodolgy we assembled papers on these dimensions and discussed their roles in separate sections. Key results retrieved from the reviewed articles (41 in total, including contributions from all the continents) comprised new methods of preferential flow and turnover times in the soil layer and concurrent impacts on stream flow generation, including intermittence analyses. Important results also comprehended global assessments of lake contamination related to urbanization, as well as reports about exacerbation of water-rock interactions caused by increasing temperatures and concomitant raise of stream water solute concentrations. A common headlight to most articles was reforestation as measure to improve catchment water storage and quality, with focuses put on catchment’s physico-chemical processes such as infiltration, properties such as porosity or root development, and water yields, depending on whether the reviewed article was dealing with support, regulation or provision services, respectively. Articles on wetlands and climate shifts were not forgotten and exposed the need to expand mangrove systems to handle water purification in lowlands, as well as the role of mediation among competing interests to mitigate water shortfalls resulting from extreme and prolonged and prolonged droughts. We believe that, altogether, the findings reported in the selected papers and summarized in the discussion allowed a panoramic view over catchments as pools of cycling water and elements, as well as on the services and disservices they can be linked to.