## 3 Case Study Results
### Historical Climate, Sea-Level Change, and Hydomorphology
#### 3.1.3 Hydomorphology  
Water in stream channels and networks originates from precipitation in the river basin (climate), overland flow, subsurface flow, and groundwater flow. The streams were in dynamic equilibrium, with the slope adjusted to provide the velocity necessary for the transportation of the eroded sediment and supply from the drainage basin. During this time, several local changes to the land and stream channels in the watershed area, as well as sea-level changes, caused streams to become unstable until equilibrium was established [27]. Natural hazards and human activities changed the existing equilibrium (order) and, subsequently, the stability of sediment supply and transport, forming unstable streams and deltas. An unstable stream attempted to adjust the slope through degrading or aggrading processes to sustain the balance (order) of the sediment supply. River energy was used for this. Sediment accumulation resulted in sediment storage along the banks and in the flood zones of the delta and was affected by vegetative cover and sunlight that penetrated the stream, channel bottom type, and diversity of vegetation that grows along the banks as the WEF moves downstream to the delta and sea [27; 28]. Further, the WEF flow, dynamic flow closures, and storage are processes that impact the sustainability of nature, stream channels, and delta hydomorphology. The historical sequence of the Neretva River and Delta's hydomorphology is divided into the following two periods:  
(i) The period of changes caused exclusively by natural forces and processes, which is the period up to the modern era (1850) (Figure 5a-c); and (ii) the period after 1850, when humans, by exploiting water resources, regulated the river and meliorated the drainage of the delta area, changing fluvial processes and the river's dynamic equilibrium (Figure 5d). Until 1850, the river system evolved slowly through natural processes, and the speed of change in system entropy, dS/dt, was extremely low. Over that long period, humans did not influence the river system, but the river influenced livelihoods in the river basin. The changes between ecology and physical habitat were not rapid; hence, human society had time to adapt to the new biophysical environment and strengthen their biophysical economy and livelihoods. The CIs of tectonics, climate, sea-level change, and seawater energy are most reflected in the lower river zone and delta's hydomorphology and biophysical environment. The tectonics and geometry of the receiving basin are defined by the hinterland characteristics, slope, relief, and discharge. Climate controls the sediment-water yield and in situ delta deposits, whereas MSL change and oceanography define river mouth processes, wave processes, tide processes, winds, nearshore currents, shelf slopes, and river system potential energy. Throughout history, the MSL change has had a long-term cumulative influence on the development of the delta, which has changed the position of the river mouth in the Adriatic Basin and, thus, the total energy of the river system [22; 28]. During the Ice Age, the river delta was in the middle of the Adriatic Basin, and unlike today, it was open to the action of waves, tides, and currents (Figure 3). As the sea level rose, the river mouth and delta reced closer to the current position, which was sheltered between the island of Hvar and the Peljesac Peninsula, reducing the influence of waves and currents and strengthening the influence of the river. Over the last 2000 years, the delta has formed within a stable dolomite and limestone valley at the top of the sea channel, protected from wave and current impacts [28]. Consequently, the Neretva River's fluvial-dominated delta was formed with microtidal settings and limited wave energy, where delta-lobe degradation was significant, and the redistribution of mouth bars was limited. The deposits of this river-dominated delta have well-developed delta-top facies comprising channel and overbank sediments.