Implications of Human Activities, Land Use Changes and Climate Variability in Mediterranean Lakes of Greece

Abstract

Lakes in the Mediterranean climate zone experience high variation in rainfall and are vulnerable to changes in climate, land cover and anthropogenically induced effects on water level and salinity. This paper presents the results from the analyses of spatiotemporal changes of land cover/uses at catchment scale of two connected lakes in Greece that have recently exhibited a dramatic loss of water volume, and investigates the potential role of climate change as a main driver of the lake water loss. The classification of the historical land cover/uses was based on a series of LANDSAT images from 1972 to 2011. Changes in the landscape structure were assessed using landscape metrics that were calculated with FRAGSTATS software. Climate data and temporal series of water level, conductivity and chloride concentration, were analyzed to investigate the potential role of climate variability to the lake hydrology and water quality. The results showed that between 1972 and 2011 almost 28% of Lake Vegoritis and 13% of Lake Petron were replaced by cultivations and reed beds. Landscape metrics showed that the lake catchment's area is highly fragmented, indicating a heterogeneous spatial pattern and degradation of the rural habitats. Regarding the climatic factors, it appears that precipitation follows a declining trend correlating with water level fluctuations. The water level in Lake Vegoritis also correlated with the conductivity and chloride concentration, indicating a relationship between hydrological alteration and water quality. Overall, a combined effect of climate-and human-induced land cover changes appeared to be responsible for the drastic environmental changes that urge the need for implementing effective restoration and mitigation measures.

Lake Restoration and Management in a Climate Change Perspective: An Introduction

“…Spatio-temporal changes were analyzed at the catchment scale of two connected lakes in Greece that have recently exhibited a dramatic loss of water volume for which climate change is potentially the main driver [23]. The results showed that almost 23% and 32% of the area of the two lakes were replaced by cultivations and reed beds from 1972 to 2011.…”

Exploring environmental predictors of aquatic macrophytes in water‐dependent Natura 2000 sites of high conservation value: Results from a long‐term study of macrophytes in Greek lakes

“…These few examples from the literature pinpoint the importance of conductivity for aquatic macrophytes. At the same time, they emphasize the need for lake managers to adjust restoration schemes in order to offset the consequences from anticipated changes in salinity and conductivity through the intensification of irrigation and agricultural practices (Stefanidis et al, ).…”

“…Particularly in the Mediterranean, studies have shown a profound effect of nutrient pollution on the total cover of submerged macrophytes, which is enhanced by water-level fluctuations. A reduced water level may enhance the cover of emergent macrophytes, exemplified by the expansion of reed beds in the littoral zone of the lakes (Papastergiadou, Retalis, Apostolakis, & Georgiadis, 2008;Papastergiadou, Retalis, Kalliris, & Georgiadis, 2007;Stefanidis, Kostara, & Papastergiadou, 2016).…”

Contribution to decision‐making on establishing the maximum water level for Lake Vegoritida

“…The lake has lost 45% of its volume and 29% of its surface area during this period (Doulgeris, Georgiou, et al., ), and the water quality of the lake has progressively deteriorated, causing a decline in the fish population and increased eutrophication from an oligotrophic to mesotrophic status (Fytianos & Muntau, ; Skoulikidis, Kaberi, & Sakellariou, ). Analysis of spatiotemporal changes in land cover/uses in the Lake Vegoritida catchment indicates the reduced water surface area was consistent with an increase in irrigated cultivations in the area (1972–2011), as well as landscape structure changes that included high fragmentation of irrigated, non‐irrigated arable land and patch‐density for reed beds (Stefanidis, Kostara, & Papastergiadou, ). The water abstraction has since ceased, with the water level now rising, and varying around to 518.5 m. For comparison, water level recordings indicate the water level was varying around 540 m a.m.s.l.…”