## 4 Discussion  
The proposed approach presents the key characteristics of the synergism of effects acting over past and future time horizons because defining future processes and conditions in the delta is difficult as local data on the future climate are insufficient and unreliable [38; 39; 40]. Historical information, though extremely general, interpreted by the proposed method determines the change in entropy in a certain period (Equation (6)) and thus becomes significant for the interpretation of hydomorphological processes in the delta. Therefore, a historic socio-hydomorphological study in the Neretva Delta can provide missing information for assessing system evolution, and at the same time, the results are visible. This study supports a decision-making framework that combines the historical experiences of the past, the constraints of the present, the visions of a possible and desirable future, the biophysical environment, and the economy. Climate models of the Neretva Basin forecast minimal changes in annual and seasonal precipitation and temperature by 2040. For the period 2040-2100, models forecast increases of 0.6-4.0\({}^{\circ}\) C in the average annual temperature and 0.9-4.7\({}^{\circ}\) C in the summer temperature, and a reduction of 2-7% in annual precipitation, with the majority occurring during summer (5-25%), followed by autumn (3-13%) and spring (3-8%). Precipitation is expected to increase by approximately 2-7% in winter [39]. A rise in the MSL in the Adriatic Sea of 15-40 cm by 2050 and 30-120 cm by 2100 has been predicted. The speed of exchange of entropy between the delta and environment, dS\({}_{\text{e}}\)/dt, plus the speed of entropy production inside the delta, dS\({}_{\text{i}}\)/dt, will increase--that is, the speed of change in delta entropy, dS/dt--but the value is difficult to predict with such general climate and MSL change data. Historical co-evolution results indicate that the delta in the future could become a submerged estuary (rias)--that is, a sea bay--owing to subsequent delta progration resulting from an MSL rise, similar to progration during the Holocene. In that case, Q\({}_{\text{river}}\cdot\text{f}_{\text{r}}<\text{r}\cdot\text{A}_{\text{delta}}\), while S\({}_{\text{delta}}>0\) and constantly increases. The delta may lose a significant part of its land surface area by 2100 and much more after that [41]. A change in the current trend of delta-forced transgression and adaptation to future climate frameworks is expensive and uncertain because the speed of change in system entropy is difficult to predict (dS\({}_{\text{delta}}\)/dt). Force transgression will not stop anytime soon because nature has sufficient energy and time to achieve an equilibrium state, and entropy has nothing to do with time. Planned man-made adaptation measures cannot permanently resist environmental energy because they are of limited duration. Hence, the problem should be solved in such a way that the exposure and entropy generation are constantly reduced (DS\({}_{\text{delta}}\to 0\)). Experts, decision-makers, and stakeholders need to find a policy for both global imbalance (climate)--that is, external entropy change--and locally generated disturbances (physical closure in the delta). Therefore, a wider scope of policies and possible technology options have been assessed. By applying a future-oriented planning methodology, two \"extreme\" policies have been considered to find a set of locally appropriate policies and options for further elaboration:  
1. A long-range sustainable policy maximizing the natural order and equilibrium state of the system. This implies a system open to natural transgression processes that lead to sustainable hydomorphological systems and ecosystems without man-made adaptation and resilience measures. This is a natural energy-based evolution and adaptation with low entropy generation. The hydromorphology and biophysical environment will be similar to those of the Roman period. Such systems will support a natural and sustainable economy. 2.