A Flood Inundation Modeling Approach for Urban and Rural Areas in Lake and Large-Scale River Basins

Fluvial floods are one of the primary natural hazards to our society, and the associated flood risk should always be evaluated for present and future conditions. The European Union’s (EU) Floods Directive highlights the importance of flood mapping as a key stage for detecting vulnerable areas, assessing floods’ impacts, and identifying damages and compensation plans. The implementation of the EU Flood Directive in Greece is challenging because of its geophysical and climatic variability and diverse hydrologic and hydraulic conditions. This study addressed this challenge by modeling of design rainfall at the sub-watershed level and subsequent estimation of flood design hydrographs using the Natural Resources Conservation Service (NRCS) Unit Hydrograph Procedure. The HEC-RAS 2D model was used for flood routing, estimation of flood attributes (i.e., water depths and flow velocities), and mapping of inundated areas. The modeling approach was applied at two complex and ungauged representative basins: The Lake Pamvotida basin located in the Epirus Region of the wet Western Greece, and the Pinios River basin located in the Thessaly Region of the drier Central Greece, a basin with a complex dendritic hydrographic system, expanding to more than 1188 river-km. The proposed modeling approach aimed at better estimation and mapping of flood inundation areas including relative uncertainties and providing guidance to professionals and academics.

Modelling Water Related Ecosystem Services in a Heavily Modified Mediterranean Reservoir Using the Soil and Water Assessment Tool (SWAT)

Lake Karla (Thessaly, Greece) drainage and morphological alterations affected all water-related ecosystem services (ES). The lake is restored as a multipurpose reservoir, whose inflows are boosted with pumping from Pinios River. The Soil and Water Assessment Tool (SWAT) simulated the watershed’s hydrology and the reservoir’s function, under a climate change scenario to assess water related ES. Official timeseries were used for five different scenarios with simulation period until 2100. The results suggest that the reservoir’s water quality is impacted by summer irrigation and by the water volume from the Pinios during winter. As for the selected ES, in almost all scenarios, they seem negatively affected.

DRAINAGE NETWORK EVOLUTION OF THE PORTAIKOS RIVER (THESSALY)

Portaikos river is a tributary of Pinios River located in Thessaly. It drains the southern part of Thessaly basin, and specifically the south part of the district of Tricala. This region is located at the border with the district of Karditsa. Portaikos River drainage basin covers an area of 294 km2, which is 2.8 % of the total drainage basin of Pinios River. The direction of Portaikos river drainage basin extends from SW-NE. The evolution of Portaikos River drainage network presents some specific morphometric features. Its analysis required the use of digital data, which were analyzed with G.I.S. software. During the study of the drainage network with the laws of drainage composition, we found a certain deviation of the 4t h and 5t h order streams. Geology has influenced significantly the estimated values of drainage density and frequency of the sub-basins. In some specific areas previous hydrographie features are inherited by the underlying rocks, which constitute the current surface morphology. The analysis of the rose diagrams of the tributaries showed a clear tendency in two main directions. The one extends from NE-SW and the other from NW-SE, almost vertical to each other. To conclude, the hypsometric (area altitude) analysis revealed that Portaikos River drainage network has developed upon a landmass of the western tectonic border of Thessaly basin.

RECENT GEOMORPHIC CHANGES AND ANTHROPOGENIC ACTIVITIES IN THE DELTAIC PLAIN OF PINIOS RIVER IN CENTRAL GREECE

The Pinios river delta is a Late Holocene arcuate type delta, located in the southern Thermaikos gulf (Central Greece). In order to determine the processes which contributed in the recent configuration of the delta, a detailed geomorphic map at the scale of 1:5000 has been prepared showing both the deltaic plain and the coastal zone features using GIS techniques. Comparative examinations of aerial photographs taken in different dates and reliable maps of the last two centuries along with field observations depict recent changes of the delta morphology. The most important factors for the development of the delta are fluvial sedimentation, wave activity and longshore currents in a tectonically active area. Land uses throughout the delta plain have been mapped in an attempt to identify socio-economic activities. The dominant feature in the deltaic plain is the numerous abandoned meandering channels. The delta shoreline is generally retreating due to marine processes especially where former river mouths occur. Finally, various future sea-level rise scenarios have been analyzed and an assessment of the impacts of the potential global future sea-level rise to the delta is estimated.