## 3 Case Study Results
### Historical Socio-Hydromorphology Assessment
Owing to the strategic importance of the delta for access from the sea to the interior of the continent, conflicts were frequent, such that the border and rulers, as well as the number of inhabitants, were constantly changing. After the medieval period, the delta belonged to the first Austrian administration of Dalmatia and Istria (1797-1805) and then briefly to the French administration (1806-1813) [34; 36]. The number of inhabitants increased significantly because of the more favorable climatic conditions after the Little Ice Age. A wider and deeper riverbed was formed, which enabled safer navigation, andlarger settlements with ports (Gabela, Metkovic, and Opuzen) developed (Figure 5c) [34]. The delta gradually filled with sediment, and the coast moved downstream (regressive coast). Lvelihoods were supported by river and delta resources, agriculture, fisheries, and trade once the delta became a regional trade hotspot [34; 36]. The physical productivity was favorable, especially for the surplus produced by agriculture. Humans did not change the river hydomorphology or delta biophysical environment. Delta resources with low entropy due to human exploitation were transformed into residuals with a slightly higher entropy, mostly of organic matter. Therefore, residuals in environments with a high receptive capacity did not threaten ecosystem functions and services. Significant and rapid changes in hydomorphology occurred from 1813 to 1918, when Croatia and B&H were governed by the second Austrian administration [16; 36]. This modern period had a favorable climate in which the river basin population grew rapidly, and larger settlements were created that changed and polluted the environment. There was sufficient financial capital to build a railway from Metkovic to the interior of B&H along the river valley (in 1855) and a river port in Metkovic, which regulated the river up to the sea to make navigation safer for large ships and protect the urban area from flooding (1881-1887) (Figure 5d) [16; 34]. By regulating the river and building embankments, flood safety was strengthened, leading to the expansion of urbanization and agricultural land, which reduced and degraded the natural environment. After the collapse of Austria-Hungary in 1918, the territory belonged to the Kingdom of Serbs, Croats, and Slovenes--that is, from 1929 to the Kingdom of Yugoslavia and after 1945 to the new Yugoslavia. During this period, the number of inhabitants continued to increase, as did urbanization, industrial development, and trade. Urbanization and industrial development occurred on land, which is the most productive agricultural area in the delta. This systematically reduced the most valuable natural resources--that is, the WEF and net products. Changes in the natural systems reduced the physical and biophysical productivity. In 1955, the marine port Ploce was built near the river mouth. Consequently, economic activities moved to the delta and coastal zone [16; 34]. Since 1963, large-scale reclamation work has been conducted in the delta [4; 16; 34]. The hydomorphology has changed in addition to the biophysical environment and socio-economy. In the upper reaches of the Neretva River in today's B&H, larger cities and industries are developing, exploiting, and polluting water resources [4; 15]. The geomorphological and hydrological systems of the river have changed significantly, which has further increased the rates of delta transgression and water salinity. Urbanization and land reclamation in the delta have increased the vulnerability of the socioeconomic system, which is worsening with climate change, and the MSL rise has caused a modern period of delta transgression. Land-water and fresh saline water interrelations, energy gradients, water salinity, and the level of surface and underground water are changing, which increases the risk of floods and the salinity of agricultural land, creating uncertainty in agricultural production [4; 37].