effects of maintenance. While stochastic viability was used, other branches of control theory may be relevant to such design and maintenance problems, both in the closed- and open-loop cases. In fact some works are very close to viability theory, such as the invariance framework [37] or reach-avoid problems in probabil- istic hybrid systems, e.g. [41,42]. They may help in the formulation and/or the resolution of time-variant reliability problems. Con- versely, reliability may be instrumental in solving control pro- blems. For instance, it is necessary to know PðXðt;yðtÞÞASðtÞÞ in viability problems, but this knowledge may not be easy to get. Time-invariant reliability methods may then provide efficient approximations of these probabilities.
The interest of the confrontation of reliability and viability does not stop with the potential methodological developments. Both theories, since they tackle very similar performance problems, have been used in fields concerned with environmental and resources management. Thus, reliability theory has been used for more than three decades for water resources systems, following the pioneering work by Hashimoto et al. [43] later completed by Moy et al. [44] and Kundzewicz and Laski [45]. It has also been used in groundwater management, be it for water quantity [46] or quality [47] issues. In ecology, the definition of ecosystem failure by Naeem [5] has fostered discussions on the link between species redundancy and ecosystem reliability [48,49]. The goal is to assess