Sperchios River Basin Research Articles

Investigating the Correlation of Tectonic and Morphometric Characteristics with the Hydrological Response in a Greek River Catchment Using Earth Observation and Geospatial Analysis Techniques

Morphometric analysis can be used to investigate catchment dynamics and tectonic processes responsible for the development of drainage catchments and to support flood risk assessment. In this study, a comparative GIS-based morphometric analysis between the main southern and northern sub-catchments of the Sperchios River basin, Central Greece, was performed, using geospatial and remote sensing data. The goal was to investigate their correlation with the peculiar geotectonic activity and the frequent flash-flood events that occur in the river floodplain. All sub-catchments characteristics are linked with the geological formation types of the area, in combination with ongoing tectonic activity. The results indicate that drainage network development is significantly controlled by the region’s overall tectonic activity. The morphometric characteristics—i.e., bifurcation ratio, drainage density, circularity ratio, elongation ratio and water concentration–time values, reflect the flood-prone character of the southern part of Sperchios River catchment in comparison to the northern part, especially during intense rainfall events. The study can provide valuable insight into identifying how morphometric characteristics are associated with increased flood hazard.

Earth Observation and GIS-Based Analysis for Landslide Susceptibility and Risk Assessment

Landslides can cause severe problems to the social and economic well-being. In order to effectively mitigate landslide hazards, the development of detailed susceptibility maps is required, towards implementing targeted risk management plans. This study aims to create detailed landslide susceptibility (LS) and landslide risk (LR) maps of the Sperchios River basin by applying an expert semi-quantitative approach that integrates the Geographic Information Systems (GIS)-based multicriteria analysis and Earth Observation (EO) data. Adopting the analytic hierarchy process (AHP) for a weighted linear combination (WLC) approach, eleven evaluation parameters were selected. The results were validated using a historic landslide database, enriched with new landslide locations mapped by satellite and aerial imagery interpretation and field surveys. Moreover, the landslide risk map of the area was also developed, based on the LS delineation, considering additionally the anthropogenic exposure and overall vulnerability of the area. The results showed that the most susceptible areas are located at the west and south-west regions of the basin. The synergistic use of GIS-based analysis and EO data can provide a useful tool for the design of natural hazards prevention policy at highly susceptible to risk landslide risk areas.

Water resources management in Sperchios River Basin, using SWOT analysis

SWOT (Strengths, Weaknesses, Opportunities and Threats) analysis is a useful tool for sustainable development and decision making about environmental planning and water resources management. This analysis was applied in order to evaluate the water resources of the wider area of Sperchios River. Sperchios River basin, with an average altitude of approximately 810m, covers an area of 2116 km2. The river is recharged by many streams of permanent and periodic flow and discharges in Maliakos Gulf. The steep slopes, which are present within approximately 2/3 of the total length of the river course, form a rather mountainous topography (streamy, with crucial flooding peaks and very intense sediment yield). Only in the last downstream part of Sperchios course, the topography gradually changes into a lowland relief, with an extent at the river mouth of 1830 km2. At this part of Sperchios severe cases of flooding have been occasionally observed and reported. Regarding the SWOT applications on the wider area of Sperchios River, various data were processed (geological, meteorological, hydrological, hydrogeological, land use, socio-economic and environmental parameters) in order to suggest a water management planning in the area.

Erosion Vulnerability Assessment of Sperchios River Basin, in East Central Greece—A GIS Based Analysis

One of the most important natural processes, with significant environmental impacts, is soil erosion. The aim of this paper is to evaluate and assess the erosion vulnerability of the geological formations constituting Sperchios River basin, in Eastern Central Greece, as well as to distinguish and locate the areas of such risk and estimate it. The developed methodology in this paper is based on Multi-Criteria Evaluation (MCE), with the implementation of Weighted Cartographic Overlay (WCO) technique in Geographic Information Systems (GIS) environment. By applying this method, an attempt was made to combine a set of factors, such as geological-hydrogeological characteristics, morphological slopes and hydrographic texture (causative factors of the phenomenon) along with rainfall (triggering factor) and land cover/use (competitive factor). The weighted combination of these factors defines the vulnerability of the formations in the area of interest. The main results of the methodology are two thematic maps of erosion vulnerability of Sperchios basin’s formations, one that does not include land use/cover factor and one with current existing conditions of the basin (co-evaluating land use/cover). In the first case, 36% of the basin surface undergoes high erosion vulnerability, while 53% present medium vulnerability. These percentages reduced significantly in the second case (3% is the high erosion vulnerability category and 38% the medium one), fact that proves the importance of vegetation in erosion restriction and protection of the geological formations consisting the Sperchios River basin.

Geomorphological quantitative analysis of Sperchios River Basin area (Central Greece) utilizing geographical information systems.

In the present study the analysis of the morphometric quantitative parameters of Sperchios river basin, and specifically of the 8 main sub-basins of the northern and southern part, have been made. The integrated use of a Geographic Information System (GIS) allows a thorough spatial analysis of the data derived from digital terrain spatial models that reveal the geomorphological characteristics of an area. The thorough analysis of the results shows the significant difference of the morphological characteristics of the northern and southern part of the catchment area, due to the impact of the neotectonic activity of the area, which creates this asymmetrical topography.

Analysis and mapping of present and future drought conditions over Greek areas with different climate conditions

Estimation of drought in a certain temporal and spatial scale is crucial in climate change studies. The current study targets on three agricultural areas widespread in Greece, Ardas River Basin in Northeastern Greece, Sperchios River Basin in Central Greece, and Geropotamos River Basin in Crete Island in South Greece that are characterized by diverse climates as they are located in various regions. The objective is to assess the spatiotemporal variation of drought conditions prevailing in these areas. The Standardized Precipitation Index (SPI) was used to identify and assess the present and future drought conditions. Future simulated data were derived from a number of Regional Climatic Models (RCMs) from the ENSEMBLES European Project. The analysis was performed for the future periods of 2021–2050 and 2071–2100, implementing A1B and B1 scenarios. The spatial analysis of the drought conditions was performed using a combined downscaling technique and the Ordinary Kriging. The Mann-Kendall test was implemented for trend investigation. During both periods and scenarios, drought conditions will tend to be more severe in the upcoming years. The decrease of the SPI values in the Sperchios River Basin is expected to be the strongest, as it is the only study area that will show a negative balance (in SPI values), regarding the drought conditions. For the Ardas and the Geropotamos River Basins, a great increase of the drought conditions will occur during the 2021–2050 period, while for 2071–2100 period, the decrease will continue but it will be tempered. Nevertheless, the situation in all study areas according to the SPI classification is characterized as “Near-normal”, in terms of drought conditions.

Present and future assessment of growing degree days over selected Greek areas with different climate conditions

The determination of heat requirements in the first developing phases of plants has been expressed as Growing Degree Days (GDD). The current study focuses on three selected study areas in Greece that are characterised by different climatic conditions due to their location and aims to assess the future variation and spatial distribution of Growing Degree Days (GDD) and how these can affect the main cultivations in the study areas. Future temperature data were obtained and analysed by the ENSEMBLES project. The analysis was performed for the future periods 2021–2050 and 2071–2100 with the A1B and B1 scenarios. Spatial distribution was performed using a combination of dynamical and statistical downscaling technique through ArcGIS 10.2.1. The results indicated that for all the future periods and scenarios, the GDD are expected to increase. Furthermore, the increase in the Sperchios River basin will be the highest, followed by the Ardas and the Geropotamos River basins. Moreover, the cultivation period will be shifted from April–October to April–September which will have social, economical and environmental benefits. Additionally, the spatial distribution indicated that in the upcoming years the existing cultivations can find favourable conditions and can be expanded in mountainous areas as well. On the other hand, due to the rough topography that exists in the study areas, the wide expansion of the existing cultivations into higher altitudes is unaffordable. Nevertheless, new more profitable cultivations can be introduced which can find propitious conditions in terms of GDD.

Landuse and NDVI change analysis of Sperchios river basin (Greece) with different spatial resolution sensor data by Landsat/MSS/TM and OLI

The assessment of land use–land cover (LULC) and normalized difference vegetation index (NDVI) changes on hydrology is essential for the development of sustainable water resource strategies. This study focuses on Sperchios river catchment, a complex and very heterogeneous area made up of numerous land covers that are difficult to map due to spectral similarities. Difficulties such as multi-seasonal spectral variables corresponding to different stages of land cover phenological development were addressed by choosing an unsupervised classification algorithm called k-means in combination with the Corine land cover database and past scientific studies. Available remote sensing data included three Landsat images (MSS, TM, OLI) all of which were resampled to a common 30-m resolution. Final LULC classifications in the period 1972–2013 separated forest, agricultural land and heath land and detected unified bare with urban land and pastures with areas of low vegetation. The recorded results include a significant reduction (–80%) of vegetation (NDVI values), 28 and 26% reduction rates in forests and pastures-low vegetation, respectively, a strong increase (114%) in heath land and an 47% increase, as concerns the agricultural land. Using of random points estimated the classification accuracy to be 75.4 and 85.2% for LULC of 1972–2013, respectively. This particular study constitutes a preliminary stage of an attempted integrated basin management of Sperchios river intending to contribute to overall ecological quality assessment of Sperchios river.

Mapping of drought for Sperchios River basin in central Greece

ABSTRACTThe estimation of drought at certain temporal and spatial scales is useful for research on climate change and global warming. Greece is often affected by droughts, which are widespread spatially and temporally due to the complex topography. Within the Greek territory, various complex microclimates are created, linked with the spatial variances in drought phenomena. In this paper an estimation of drought in the Sperchios River basin was conducted using the Aridity Index (AI). Additionally, a seasonal analysis of drought was performed. Meteorological data from the Hellenic National Meteorological Service (HNMS) were used as inputs for the AI equation. Spatial interpolation of AI for the Sperchios River basin was performed using a kriging method by the application of ArcGIS 9.3. In order to produce required input data, several models (EmPEst, RayMan) and techniques (linear regression, interpolation) were combined. Finally, the meteorological data series were randomly separated into two periods and AI was estimated for these sub-periods, in order to test the effectiveness of the drought index used. The results indicate that the conditions prevailing in the area are humid, mostly affected by increased rainfall occurring in the mountainous section of the basin. Broadly, the humid environment in the upstream of Sperchios River prevents drought occurring in the lowlands of Sperchios River valley. Nevertheless, some differentiation appeared during the summer period, to which special attention needs to be given in order to prevent drought conditions.Editor Z. W. Kundzewicz Associate editor not assigned

Sensitivity analysis and comparison of various potential evapotranspiration formulae for selected Greek areas with different climate conditions

Potential evapotranspiration (PET) is one of the most critical parameters in the research on agro-ecological systems. The computational methods for the estimation of PET vary in data demands from very simple (empirically based), requiring only information based on air temperatures, to complex ones (more physically based) that require data on radiation, relative humidity, wind speed, etc. The current research is focused on three study areas in Greece that face different climatic conditions due to their location. Twelve PET formulae were used, analyzed and inter-compared in terms of their sensitivity regarding their input coefficients for the Ardas River basin in north-eastern Greece, Sperchios River basin in Central Greece and Geropotamos River basin in South Greece. The aim was to compare all the methods and conclude to which empirical PET method(s) better represent the PET results in each area and thus should be adopted and used each time and which factors influence the results in each case. The results indicated that for the areas that face Mediterranean climatic conditions, the most appropriate method for the estimation of PET was the temperature-based, Hamon’s second version (PETHam2). Furthermore, the PETHam2 was able to estimate PET almost similarly to the average results of the 12 equations. For the Ardas River basin, the results indicated that both PETHam2 and PETHam1 can be used to estimate PET satisfactorily. Moreover, the temperature-based equations have proven to produce better results, followed by the radiation-based equations. Finally, PETASCE, which is the most commonly used PET equation, can also be applied occasionally in order to provide satisfactory results.

Integrated analysis of present and future responses of precipitation over selected Greek areas with different climate conditions

The assessment of future precipitation variations prevailing in an area is essential for the research regarding climate and climate change. The current paper focuses on 3 selected areas in Greece that present different climatic characteristics due to their location and aims to assess and compare the future variation of annual and seasonal precipitation. Future precipitation data from the ENSEMBLES anthropogenic climate-change (ACC) global simulations and the Climate version of the Local Model (CLM) were obtained and analyzed. The climate simulations were performed for the future periods 2021–2050 and 2071–2100 under the A1B and B1 scenarios. Mann–Kendall test was applied to investigate possible trends. Spatial distribution of precipitation was performed using a combination of dynamic and statistical downscaling techniques and Kriging method within ArcGIS 10.2.1.The results indicated that for both scenarios, reference periods and study areas, precipitation is expected to be critically decreased. Additionally, Mann–Kendall test application showed a strong downward trend for every study area. Furthermore, the decrease in precipitation for the Ardas River basin characterized by the continental climate will be tempered, while in the Sperchios River basin it will be smoother due to the influence of some minor climatic variations in the basins' springs in the highlands where milder conditions occur. Precipitation decrease in the Geropotamos River basin which is characterized by Mediterranean climate will be more vigorous. B1 scenario appeared more optimistic for the Ardas and Sperchios River basins, while in the Geropotamos River basin, both applied scenarios brought similar results, in terms of future precipitation response.

Comparative analysis of soil erosion sensitivity using various quantizations within GIS environment: an application on Sperchios river basin in Central Greece

ABSTRACTSoil erosion is a prominent cause of land degradation and desertification in Mediterranean countries. The detrimental effects of soil erosion are exemplified in climate (in particular climate change), topography, human activities and natural disasters. Modelling of erosion and deposition in complex terrains within a geographic information system (GIS) requires reliable estimation of topographic factors, as well as the formulation of erosion models adequate for digital representation of spatially distributed parameters. In the current paper, two different approaches for the estimation of erosion in the Sperchios river basin are described and evaluated using GIS – the Revised Universal Soil Loss Equation and the Gavrilovič method. Implementing the ArcGIS 10.2.1 programme, the necessary input data for these approaches were estimated using four different quantizations that were created using topographic maps, courtesy of the Greek Geographical Army Service. The results indicated that even though a high-resolution quantization is always preferred for more reliable results, when there is a lack of available data, coarser quantizations can also be used to extract similar estimations.

Hydrological simulation of Sperchios River basin in Central Greece using the MIKE SHE model and geographic information systems

The MIKE SHE model is able to simulate the entire stream flow which includes direct and basic flow. Many models either do not simulate or use simplistic methods to determine the basic flow. The MIKE SHE model takes into account many hydrological data. Since this study was directed towards the simulation of surface runoff and infiltration into saturated and unsaturated zone, the MIKE SHE is an appropriate model for reliable conclusions. In the current research, the MIKE SHE model was used to simulate runoff in the area of Sperchios River basin. Meteorological data from eight rainfall stations within the Sperchios River basin were used as inputs. Vegetation as well as geological data was used to perform the calibration and validation of the physical processes of the model. Additionally, ArcGIS program was used. The results indicated that the model was able to simulate the surface runoff satisfactorily, representing all the hydrological data adequately. Some minor differentiations appeared which can be eliminated with the appropriate adjustments that can be decided by the researcher′s experience.