## 3 Case Study Results
### Historical Socio-Hydromorphology Assessment  
River and delta hydromorphologies are indicators of the constant effort of a natural system to establish an equilibrium state (order) that reduces entropy and sustains the system functions that support the biophysical environment and human society. Historic maps, to some extent, reveal such historic socioeconomic changes, whereas hydrogeological profiles present historic sediment buildups that support the maps. Until 1850, socio-hydromorphological changes were induced by natural forces and processes that operated globally and regionally, independent of humanity. Owing to the limited technology during this period, humans only slightly changed the hydromorphology and system state locally (entropy generation). Throughout history, humans have developed and used different technologies that retroactively influence and change the environment, which then influences society and the economy [33]. In ancient times, the number of inhabitants in the delta was small, and they lived in small settlements on the rocky limestone and dolomite terrain of the delta area, away from the water and flooding zones. Therefore, they exploited WEF resources with environmentally friendly technology, and the human influence on the river system was negligible [33; 34]. During this period, the local economy was a subsystem of the river or delta ecosystem, and there were no limits on the biophysical throughput of WEF resources from the ecosystem through the economic subsystem and back to the ecosystem as waste. In antiquity, the number of inhabitants grew, and Narona, the largest Roman city, was built on the foundations of the Greek emporium that existed from the 4 th to the 2 nd century BC (Figure 5a) [35]. The city had more than 20,000 inhabitants engaged in trade and craftsmship. It was abandoned around AD 600 and never rebuilt [34; 35]. Like other Roman cities on the seacoast, this city had a port and urban water infrastructure. City and human activities did not significantly impact the hydromorphological and ecological features of the area or the sustainability of nature and humans. During the antiquity period, the climate and slow MSL rise changed the biophysical environment of the bay, which gradually evolved into a shallow wetland delta. The swampy environment was not well suited to life, and navigation from the sea to Narona was difficult, threatening the city's trade and prosperity. Therefore, with great certainty, we can assume that Narona was abandoned because of climate change (variable and cold weather) and the extremely slow rise of the MSL that caused delta regression [35]. Various political problems in the Roman Empire caused by climate change also contributed to the city's desertion [19]. Delta regression continued into the modern period. With the beginning of the medieval historical period (AD 476-1400), after the fall of the Western Roman Empire, significant climatic and socioeconomic changes occurred in a wide area, as well as human conflicts [36]. Consequently, the number of inhabitants diminished. This was the period during which the delta area was mostly under Croatian rule [36]. Agriculture was the primary source of income. Owing to regression processes, the fertility of the river valley increased, and the biophysical environment and economy became stronger. The population still preferred living in smaller settlements, mostly in the rocky limestone areas around the delta. The settlement of Gabela, which was located at the beginning of the delta, developed into a new main port and place of trade because the river was navigable for smaller ships (Figure 5b) [34]. After the Croatian rulers, the Neretva River Basin belonged to the Ottoman Empire and Republic of Venice (1420-1797) [34; 36]. The middle and upper river zones up to Gabela belonged to the Ottoman Empire, and the delta was mainly governed by the Republic of Venice.