Assessing the impacts of land use/land cover (LULC) change and the effects of nature-based solutions in Andean basins.

The limited spatial scope of Andean basins conservation agreements by nature-based solutions (NbS) in the tropical alpine grassland region (páramos) has led to unequal protection of upstream ecosystems, endangering the water quality downstream of large Andean cities. Simultaneously, the páramos have been converted to other land uses in response to the political, economic, social, technological, ecological, and legal (PESTEL) factors. In this context, we aim to compare the negative impacts associated with land use/land cover (LULC) change and the positive effects of nature-based solutions in the upper Andean basins using remote sensing data, PESTEL analysis, and water quality assessment. The upper basin of the Pita and Cutuchi rivers, located above 3,000 m.a.s.l., which supply drinking and irrigation water to two major Andean cities in Ecuador, i.e., Quito (the capital of Ecuador) and Latacunga (an important city for floriculture and agriculture), were examined in comparison as case studies between 1999 and 2022. Our results reveal significant land-use changes from páramo to agriculture, Pinus plantations, urban growth, and mining areas in the upper basin of the Cutuchi river, driving water quality between low to moderate for drinking and irrigation purposes. According to the PESTEL framework, the main factors contributing to the lack of upper basin protection are (1) short-term policies in line with the political party, (2) state budget planning that does not meet restoration needs, (3) conflicts between the upper, middle, and lower river basin communities, (4) lack of public investment in technological tools, (5) agricultural practices in the páramo due to high soil carbon storage in comparison to other areas and (6) conflicting laws between administrative divisions. In contrast, main páramo areas have remained unaltered or passively restored in the upper basin of the Pita river by the combination of NbS and policies implemented by water funds, conserving good water quality. By using these catchments as ideal natural laboratories, we can demonstrate the positive experiences through NbS in river basin management. Together with our PESTEL analyses, it is possible to develop integral conservation projects that ensure human health and sustainable agricultural productivity in the context of Sustainable Development Goal (SDG) 6: Clean Water and Sanitation.