**4. Conclusion and future directions**

With respect to this study, the authors identified that more and more research related to composite indexes include parameters of culture, economics, politics, institutions, governance, and social issues. It also was notable that there is not a perfect number of indicators to compose an index, while some investigations use five indicators, others could use 115, all depending on the detailed framework wanted. On the other hand, the absence of data available, affordable, or accessible is summed to the reasons to avoid utilizing specific indicators; nevertheless, the use of indexes is still creating scientific publications.

Considering all the points exposed in this manuscript, the final purpose to elaborate this systematic review was envisioning the creation of an ecohydrological composite index for basins, which currently does not exist. The work pretends to be a framework to strengthen ecosystems' sustainability and to ensure water demands. An end-user tool that processes the indicators' values and calculations of the ecohydrological composite index is also in plans to develop.
