PHO - Pinios Hydrologic Observatory, Greece

"PHO is located at the eastern boundary of River Pinios Basin (RPB) and covers an area of about 45 km² (Fig. 1a). According to the hydrolithological map presented in Fig. 1b, three are the dominant hydrolithological units identified in PHO: a) the fractured formations of low to medium permeability (HA2) located at the northern mountainous part of the watershed, which consist mainly of gneiss, gneiss-schists and ultrabasic formations (amphibolites and prasinites). Within these units, groundwater flow occurs predominantly through their tectonically driven fractures (secondary porosity) and to a less extent through the primary porosity, b) the alluvial deposits of variable permeability (HP1) that consist mainly of recent deposits of variable texture including lateral screes, that fill the basin at the southern plain part of PHO watershed, in which a groundwater system of medium potential is formed, and c) old talus cones and scree of variable permeability (HP4), in which direct infiltration of precipitation is favored compared to the alluvia.

Fig. 1: Spatial information for PHO watershed: a) location map of PHO in RPB, and RPB in Greece, b) hydrolithological map, c) land cover map according to CORINE classification and d) observations network distribution and digital elevation model (adopted from Panagopoulos et al., 2018)

With regard to land cover (Fig. 1c), the northern mountainous part of the watershed is dominated by mixed forests, while transitional woodland-scrubs, broad-leaved forests and natural grasslands also occur. This land cover is developed in a sloppy terrain with the altitude ranging between 400 and 1500 m. The southern plain part of the watershed including the transition zone is dominated by fruit trees, the most significant of which are apples and cherries, while limited areas cultivated with annual crops, such as winter wheat and maize, are also met. Medium slopes are identified in the transition zone with altitude ranging between 150 and 250 m, and low slopes are met in the plain part in which altitude ranges between 100 and 150 m and the alluvial groundwater system occurs. Based on data retrieved from five soil profiles located in the plain part of PHO watershed, soils of sandy loam texture are dominant, while sandy clay loam and loamy soils were also identified."

Pisinaras, V., Panagopoulos, A., Herrmann, F., Bogena, H.R., Doulgeris, C., Ilias, A., Tziritis, E., Wendland, F., 2018. Hydrologic and Geochemical Research at Pinios Hydrologic Observatory: Initial Results. Vadose Zone Journal, 17(1): 0. DOI: 10.2136/vzj2018.05.0102