# Explaining and Measuring Social-Ecological Pathways: The Case of Global Changes and Water Security
## 2 Social-Ecological Systems and Evolution: Theoretical Framework
### An Institutional and Cognitive Model of Change
#### 2.2.2 Explaining the Saturation of a Social-Ecological System  
The rigidity trap reflects the equilibrium where the SES's internal controls lock the system into a pathway that reinforces undesirable outcomes [27; 29]. It is a dynamic leading to an organizational status-quo which produce a vicious circle. It is a particular setting where the refinements of the management model and of the institutional design have organized exploitation of the resource characterized by a low natural diversity and a low variation in resource dynamics to maximize the economic use of the resource [23; 36]. The governance design appears robust because institutions are highly connected, self-reinforcing, and inflexible, which constrains the innovation ability of the SES [36]. Even if the outcome reveals to be undesirable, the SES is unable to explore any alternative patterns, increasing its vulnerability to disturbance. As a result, the system cannot evolve anymore within the same stability domain and is likely to experience a structural crisis [27; 29; 36]. For example, a rigidity trap may be a SES organizing an ecologically clean over-exploitation of the resource, which is frequent when public policies do not distinguish the resource from its uses [37; 38].  
The institutional complexity trap concept puts forward that the extent of the regulatory scope of a given SES has a decreasing marginal impact on its coordination efficiency [30; 31]. The governance of any environmental resource is a regime of multiple public policies and property rights specific to different uses of the same shared-resource [38; 39]. The regime efficiency (integration) to govern behaviors depends on the scope of regulated uses (extent) and the coherence of the public policies and property rights that structure the regulation.  
Together, extent and coherence increase the integration of the regime, and thus the potential efficiency of the governance design. This relation is not linear, the marginal impact of extent on integration is decreasing (Figure 2) [31]. Indeed, the increase of the regime extent impacts negatively on its coherence because of institutional overlaps and frictions. As an illustration, water uses are regulated by policies specific to agriculture, environment, urban planning, and energy, among others; however, these policies could be conflictual or not consistent while overlapping. These overlaps correspond to transversal transaction costs that reduce the efficiency of the coordination and lock the SES in a state of non- feasible additional progress under the same structural conditions. Indeed, the regime is no longer able to coordinate additional trade-offs between different uses and policy objectives [40; 41] because transversal transaction costs limit the overall coherence of the regime. The SES becomes vulnerable to disturbances, opening the room for a release and marking the end of the  
Figure 1: Heuristic scheme of an adaptive cycle.  
saturation phase. Over time, expertise in governance stresses the increase of transversal transaction costs by developing siloization and uncoordinated extension of the regime [42].  
The rigidity trap produces a lack of adaptive capacity and the institutional complexity trap constrains the ability to refine coordination mechanisms. Taken together, these traps drive the SES to a state where it is robust to shock but not necessarily resilient anymore. The SES is vulnerable to disturbances and likely to know a structural crisis, entering into Phase 2 of an adaptive cycle.