The present paper presents measurements of water flow and suspended particulate material of Pinios River (Thessaly) during the hydrological year 2013/2014. The measurements were carried out in two positions before Pinios enters the agricultural deltaic plain and one inside the delta. Furthermore, an effort is made to estimate the water contribution to Pinios by the springs of Tempi valley and the quantity of water being diverted to the old river bed for irrigation purposes. These measurements were compared to corresponding data from the hydrological year 2012/13 and the significant differences that arose can be attributed to decreased rainfall and probably to the operation of a gate valve in Girtoni, that was initiated in the dry period of 2014.

This paper addresses the critical issue of how wrong can water resources management go if the structure and hydrodynamic evolution of the exploited system is not well known. As a case study the River Pinios estuarine groundwater system in central Greece, is discussed. The study area has a spatial extent of about 80km2 and a typical estuarine shape. Due to the neotectonic evolution and the eustatic moves, a unique geomorphological environment and a dense hydrological network have been developed. Dominant socioeconomic activity in the region is agriculture and secondarily tourism that is focused only along a narrow strip along the coastal line and occurs only seasonally. Domestic water demands are covered by groundwater abstractions mainly from deeper wells drilled at the margins of the estuarine. Shallow wells in the alluvial sediments of the basin augment irrigation demands that are predominantly catered by surface water from the river Pinios and its tributaries, and to a minor extent several springs that emerge along the marginal fans of the basin. Due to the shallow groundwater levels, a large percentage of irrigation demands is covered by direct osmosis of water from the root zone.

In tectonically active areas, such as in the northwest Peloponnese of western Greece, geomorphic processes are strongly influenced by active faulting; in many cases such faults cannot be easily identified. In this paper we apply multidisciplinary analysis (morphotectonic indices, neotectonic mapping, geophysical surveys and remote sensing techniques) to map the recently-recognized east–west trending Pineios River normal fault zone with a high degree of accuracy, and to better understand its contribution to the evolution of the ancient region of Elis during Holocene time. Fault activity seems to be related to frequent changes in river flow patterns and to displacements of the nearby shoreline. We argue that fault activity is the main reason for migration of Pineios river mouth as documented for several time periods during historical time. Quantitative constraints on deformation caused by the faulting were applied through the application of the morphotectonic indices proposed in this paper, including drainage network asymmetry and sinuosity, and mountain front sinuosity, all of which indicate that this is a highly active structure. Slip rates calculated to be as high as 0.48 mm/yr for the last 209 ka (based on previously published dating) were verified by applied geophysical methods. The fault surface discontinuity was identified at depth using vertical electrical resistivity measurements and depositional layers of different resistivity were found to be clearly offset. Displacement increases toward the west, reaching an observed maximum of 110 m. The most spectacular landform alteration due to surface deformation is the north–south migration of the river estuary into completely different open sea areas during the late Quaternary, mainly during the Holocene. The sediment transport path has been altered several times due to these changes in river geometry with and the most recent seeming to have occurred almost 2000 years ago. The river estuary migrated to its contemporary position along the southern coast, settled on the hanging wall, inducing retrograding of the northern coast, and settled on the foot wall, with rates reaching the order of 0.52 m/yr, as concluded from historical and recently-acquired remote sensing data.