Relationship of Weather Types on the Seasonal and Spatial Variability of Rainfall, Runoff, and Sediment Yield in the Western Mediterranean Basin

Rainfall is the key factor to understand soil erosion processes, mechanisms, and rates. Most research was conducted to determine rainfall characteristics and their relationship with soil erosion (erosivity) but there is little information about how atmospheric patterns control soil losses, and this is important to enable sustainable environmental planning and risk prevention. We investigated the temporal and spatial variability of the relationships of rainfall, runoff, and sediment yield with atmospheric patterns (weather types, WTs) in the western Mediterranean basin. For this purpose, we analyzed a large database of rainfall events collected between 1985 and 2015 in 46 experimental plots and catchments with the aim to: (i) evaluate seasonal differences in the contribution of rainfall, runoff, and sediment yield produced by the WTs; and (ii) to analyze the seasonal efficiency of the different WTs (relation frequency and magnitude) related to rainfall, runoff, and sediment yield. The results indicate two different temporal patterns: the first weather type exhibits (during the cold period: autumn and winter) westerly flows that produce the highest rainfall, runoff, and sediment yield values throughout the territory; the second weather type exhibits easterly flows that predominate during the warm period (spring and summer) and it is located on the Mediterranean coast of the Iberian Peninsula. However, the cyclonic situations present high frequency throughout the whole year with a large influence extended around the western Mediterranean basin. Contrary, the anticyclonic situations, despite of its high frequency, do not contribute significantly to the total rainfall, runoff, and sediment (showing the lowest efficiency) because of atmospheric stability that currently characterize this atmospheric pattern. Our approach helps to better understand the relationship of WTs on the seasonal and spatial variability of rainfall, runoff and sediment yield with a regional scale based on the large dataset and number of soil erosion experimental stations

A Comparative Analysis of a Detailed and Semi-Detailed Soil Mapping for Sustainable Land Management Using Conventional and Currently Applied Methodologies in Greece

Two soil mapping methodologies at different scales applied in the same area were compared in order to investigate the potential of their combined use to achieve an integrated and more accurate soil description for sustainable land use management. The two methodologies represent the main types of soil mapping systems used and still applied in soil surveys in Greece. Diomedes Botanical Garden (DBG) (Athens, Greece) was used as a study area because past cartographic data of soil survey were available. The older soil survey data were obtained via the conventional methodology extensively used over time since the beginnings of soil mapping in Greece (1977). The second mapping methodology constitutes the current soil mapping system in Greece recently used for compilation of the national soil map. The obtained cartographic and soil data resulting from the application of the two methodologies were analyzed and compared using appropriate geospatial techniques. Even though the two mapping methodologies have been performed at different mapping scales, using partially different mapping symbols and different soil classification systems, the description of the soils based on the cartographic symbols of the two methodologies presented an agreement of 63.7% while the soil classification by the two taxonomic systems namely Soil Taxonomy and World Reference Base for Soil Resources had an average coincidence of 69.5%

Detailed Soil Survey Field and Laboratory Data as a Critical Tool for Optimizing the Arable Cropping Capability Evaluation of a Representative Episaturated Soil Pedon in Greece

The objective of the present work is to contribute to the examination of the interconnections between soil classification/soil mapping and soil capability for agricultural use. A pedon scale analytical field along with laboratory data of an episaturated agricultural soil of Thessaly (Greece), allowed for the optimization of soil fertility class evaluation and its corresponding agricultural value. Specific soil properties, low chroma colors and the distribution of redoximorphic features within the soil profile (Fe-Mn concretions) revealed the presence of impermeable argillic horizons, resulting in a perched water table in late winter and spring. The evaluation of the soil pedon was carried out through the accurate parameterization and implementation of a technical soil classification system and a soil rating method, both of which are well known worldwide, and which use detailed soil survey data. The results confirmed the general principle that only by using detailed soil survey field and laboratory data can any technical soil classification system or soil rating method be adapted and properly applied. Both the classification system and the scoring methodology of the soil profile reached the same conclusion: characterizing the studied soil as of good potential for general arable cropping or as of fair agricultural value. This was achieved only by considering the phenomenon of episaturation, which emerged from the plethora of detailed soil survey data, guiding the classification system and the scoring methodology to produce reliability and represent real situation results

Detailed Soil Survey Field and Laboratory Data as a Critical Tool for Optimizing the Arable Cropping Capability Evaluation of a Representative Episaturated Soil Pedon in Greece

The objective of the present work is to contribute to the examination of the interconnections between soil classification/soil mapping and soil capability for agricultural use. A pedon scale analytical field along with laboratory data of an episaturated agricultural soil of Thessaly (Greece), allowed for the optimization of soil fertility class evaluation and its corresponding agricultural value. Specific soil properties, low chroma colors and the distribution of redoximorphic features within the soil profile (Fe-Mn concretions) revealed the presence of impermeable argillic horizons, resulting in a perched water table in late winter and spring. The evaluation of the soil pedon was carried out through the accurate parameterization and implementation of a technical soil classification system and a soil rating method, both of which are well known worldwide, and which use detailed soil survey data. The results confirmed the general principle that only by using detailed soil survey field and laboratory data can any technical soil classification system or soil rating method be adapted and properly applied. Both the classification system and the scoring methodology of the soil profile reached the same conclusion: characterizing the studied soil as of good potential for general arable cropping or as of fair agricultural value. This was achieved only by considering the phenomenon of episaturation, which emerged from the plethora of detailed soil survey data, guiding the classification system and the scoring methodology to produce reliability and represent real situation results

Study of factors affecting land desertification

Two vulnerable to desertification areas, representative of the Mediterranean environment and important for the Greek land use conditions, were used as research fields of the present thesis. The areas which are dominated by different soil and climatic characteristics and land use intensities occupy an area of approximately one million acres and located in the prefectures of Chania and Heraklion on the island of Crete.A significant portion of these areas was mapped and studied on the basis of soil, climate and growing vegetation features. By completing questionnaires with the participation of local producers, a set of 70 biophysical and socioeconomic indicators were recorded at farm level on a sample of 171 fields (locally). In the context of this study and according to the implementation of the research project DESIRE, the use of data, obtained from 18 research areas at regional level (1785 questionnaires), was granted. In two of the main land uses (olive grove and pasture) of the research areas of Crete automatic data loggers and meteorological stations were established for a period of three years (2008-2011). The experimental devices and the stations were used to provide a quantitative assessment of surface water erosion and sediment loss under various traditional farming practices and use intensities.The abovementioned samples of questionnaires data (regional and local scale) were analyzed statistically in order to extract the most important indicators that influence desertification risk, according to land degradation process and mainly because of surface water erosion, at regional and local level. Especially at local level and specifically on data from the questionnaires of Crete an innovative statistical strategy was implemented by using exploratory multivariate nonparametric statistical tests and the field estimated parameter of erosion degree. Utilizing the results from the experimental recording of surface water erosion and soil sediment loss, the effect of different agricultural techniques and land management practices in desertification due to erosion was evaluated in the two representative land uses of the Mediterranean environment. Additionally the data of the three-year period allowed the experimental confirmation of the estimated by the P.E.S.E.R.A. (Pan-European Soil Erosion Risk Assessment) methodology erosion risk at field level (local scale). Τhe application of P.E.S.E.R.A. and E.S.A. (Environmentally Sensitive Areas) methodologies at regional level for the study area of Chania under the conditions of 28 different farming practices and land management scenarios has been the last approach for the study of desertification. This approach aimed at comparative analysis of management scenarios, regarding their impact on erosion and desertification risk at Prefecture level.The logical framework developed in this thesis combined with the empirical analysis based on descriptive, exploratory, inductive and multivariate statistics allows the assessment of desertification risk, with the use of a limited number of indicators in different areas of environmental sensitivity by utilizing data of regional or local level. As in situ quantitative measurements of surface water erosion and soil sediment loss are rare, the importance of experimental data that used for the evaluation of specific farming practices contribution to environmental sustainability at farm level is invaluable. The experimental evaluation of farming practices can overturn misconceptions about the cultivation of land and protect the environment by preventing further degradations. Furthermore the use of reliable scientific simulation models for erosion risk estimation (P.E.S.E.R.A.) and methodologies for the assessment of desertification risk (E.S.A.) allow the verification of the impact of traditional or innovative practices in the sustainability of natural resources on a regional scale. Such simulations can be considered as valuable "tools" for those with responsibility for policy decisions concerning agriculture and the environment.Δύο ευαίσθητες περιοχές στην ερημοποίηση, αντιπροσωπευτικές του Μεσογειακού περιβάλλοντος με σημαντικές για τις Ελληνικές συνθήκες χρήσεις γης, χρησιμοποιήθηκαν ως πεδία έρευνας της παρούσας διατριβής. Οι περιοχές αυτές που χαρακτηρίζονται από διαφορετικά εδαφοκλιματικά χαρακτηριστικά και εντάσεις χρήσεων γης καταλαμβάνουν κατά προσέγγιση έκταση ενός εκατομμυρίου στρεμμάτων και βρίσκονται στους νομούς Χανίων και Ηρακλείου της νήσου Κρήτης. Σημαντικό τμήμα των περιοχών αυτών χαρτογραφήθηκε και μελετήθηκε ως προς τα εδάφη, την αναπτυσσόμενη βλάστηση και το κλίμα ενώ παράλληλα με τη χρήση ερωτηματολογίων και τη συμμετοχή των τοπικών παραγωγών καταγράφτηκαν σε επίπεδο αγροκτήματος ένα σύνολο από 70 βιοφυσικούς και κοινωνικοοικονομικούς δείκτες σε δείγμα 171 αγροκτημάτων (τοπικό επίπεδο). Στο πλαίσιο της παρούσας διατριβής και της υλοποίησης του ερευνητικού προγράμματος DESIRE παραχωρήθηκε η χρήση των δεδομένων 1785 αντίστοιχων ερωτηματολογίων από 18 περιοχές έρευνας παγκόσμιας κλίμακας (περιφερειακό επίπεδο). Σε δύο από τις κύριες χρήσεις γης (ελαιώνας και βοσκότοπος) των περιοχών έρευνας της Κρήτης εγκαταστάθηκαν για τρία χρόνια (2008-2011) αυτόματοι σταθμοί καταγραφής εδαφικών και μετεωρολογικών δεδομένων με σκοπό την ποσοτική εκτίμηση της επιφανειακής υδατικής διάβρωσης και της απώλειας εδαφικού ιζήματος σε διάφορες παραδοσιακές καλλιεργητικές πρακτικές και εντάσεις χρήσης.Τα δύο προαναφερόμενα δείγματα των ερωτηματολογίων (περιφερειακής και τοπικής κλίμακας) αναλύθηκαν στατιστικά προκειμένου να εξαχθούν οι πιο σημαντικοί δείκτες που επηρεάζουν τον κίνδυνο ερημοποίησης των γαιών ανά διεργασία υποβάθμισης και κυρίως εξαιτίας της επιφανειακής υδατικής διάβρωσης σε περιφερειακό και τοπικό επίπεδο. Ειδικά σε τοπικό επίπεδο και συγκεκριμένα στα δεδομένα των ερωτηματολογίων της Κρήτης εφαρμόστηκε μια καινοτόμος στρατηγική στη στατιστική ανάλυση με την εκτέλεση διερευνητικών μη παραμετρικών πολυμεταβλητών στατιστικών ελέγχων και τη χρήση της εκτιμώμενης στον αγρό ιδιότητας του βαθμού διάβρωσης. Χρησιμοποιώντας τα αποτελέσματα της πειραματικής καταγραφής της επιφανειακής υδατικής διάβρωσης και της απώλειας εδαφικού ιζήματος για τρία χρόνια αξιολογήθηκε η επίδραση διαφορετικών καλλιεργητικών πρακτικών και διαχειρίσεων των γαιών στην ερημοποίηση λόγω διάβρωσης σε δύο αντιπροσωπευτικές χρήσεις γης του Μεσογειακού περιβάλλοντος. Επίσης με τα δεδομένα των τριετών μετρήσεων πραγματοποιήθηκε πειραματική επιβεβαίωση του εκτιμώμενου με χρήση της μεθοδολογίας P.E.S.E.R.A. (Pan–European Soil Erosion Risk Assessment) κινδύνου διάβρωσης σε επίπεδο αγροτεμαχίου (τοπική κλίμακα) δεδομένου ότι το μοντέλο είχε ήδη προσαρμοσθεί στις μεσογειακές και ειδικά στις ελληνικές συνθήκες από παλαιότερες εργασίες. Ολοκληρώνοντας τις προσεγγίσεις της μελέτης του φαινομένου της ερημοποίησης των γαιών πραγματοποιήθηκε η εφαρμογή των μεθοδολογιών P.E.S.E.R.A. και E.S.A. (Environmentally Sensitive Areas) σε περιφερειακό επίπεδο για την περιοχή μελέτης του νομού Χανίων και στις συνθήκες 28 διαφορετικών σεναρίων καλλιεργητικών πρακτικών και διαχείρισης των γαιών με στόχο τη συγκριτική ανάλυση των σεναρίων διαχείρισης και καλλιέργειας των γαιών ως προς τον κίνδυνο διάβρωσης και ερημοποίησης σε επίπεδο νομού. Το λογικό πλαίσιο που αναπτύχθηκε στην παρούσα διατριβή σε συνδυασμό με την εμπειρική ανάλυση που βασίστηκε σε περιγραφική, διερευνητική, επαγωγική και πολυπαραγοντική στατιστική επεξεργασία, επιτρέπει την εκτίμηση του κινδύνου ερημοποίησης των γαιών, με τη χρήση περιορισμένου αριθμού δεικτών, σε περιοχές διαφορετικής περιβαλλοντικής ευαισθησίας αξιοποιώντας δεδομένα περιφερειακού ή τοπικού επιπέδου. Καθώς επιτόπιες ποσοτικές μετρήσεις της επιφανειακής υδατικής διάβρωσης και της απώλειας εδαφικού ιζήματος είναι σπάνιες η αξία της χρήσης των πειραματικών δεδομένων για την αξιολόγηση της συνεισφοράς συγκεκριμένων καλλιεργητικών πρακτικών στην αειφορία του περιβάλλοντος σε επίπεδο αγροκτήματος είναι ανεκτίμητη. Η πειραματική αξιολόγηση των καλλιεργητικών πρακτικών είναι δυνατόν να ανατρέψει λανθασμένες αντιλήψεις για την καλλιέργεια των γαιών και την προστασία του περιβάλλοντος αποτρέποντας περαιτέρω υποβαθμίσεις. Επιπρόσθετα με τη χρήση αξιόπιστων επιστημονικών μοντέλων προσομοίωσης της επιφανειακής υδατικής διάβρωσης (P.E.S.E.R.A.) για την εκτίμηση του κινδύνου διάβρωσης και εκτίμησης του κινδύνου ερημοποίησης (E.S.A.) καθίσταται εφικτή η εξακρίβωση της επίδρασης των παραδοσιακών ή καινοτόμων πρακτικών στην αειφορία των φυσικών πόρων σε περιφερειακή κλίμακα. Τέτοιου είδους προσομοιώσεις είναι δυνατόν να θεωρηθούν ως πολύτιμα «εργαλεία» για τους έχοντες την ευθύνη λήψης πολιτικών αποφάσεων που αφορούν τη γεωργία και το περιβάλλον

Map-based soil crusting susceptibility assessment using pedotransfer Rules, CORINE and NDVI: A preliminary study in Greece

Map-based assessment of land degradation processes supports national monitoring and protection of the soil resources, in line with the Land Degradation Neutrality (LDN) and the Sustainable Development Goals (SDGs) initiatives. Soil crusting susceptibility, a complex expression of land degradation, with fundamental impact on soil functions, has not yet been estimated in Greek territory. To address this knowledge gap, current research uses well-known pedotransfer rules (PRLeB), partially adjusted to suit the local soil database format. The PRLeB, already applied at European scale, examine the soil crusting problem as a function of fundamental soil characteristics. From the first analysis a paradox emerged. Moderately and highly crusting prone soils were encountered in forested areas. This paradox indicated the need for a second formalization of the soil crusting problem (ePRLeB). The CORINE Land Cover (CLC) 2018 and a seasonal vegetation cover index (Normalized Difference Vegetation Index -NDVI) were used to divide the study area into categories and to capture the temporal variability of the problem, accordingly. Three land use categories emerged. The water bodies and the artificial areas were characterized as Non-evaluated areas (NE). Areas with considerable vegetation coverage (NDVI greater than 0.5) were characterized as Non-prone to crusting (NC), and the rest of the areas were characterized as Potentially prone to crusting (PC). The PRLeB approach was applied only to the PC areas. In both formalizations, the physicochemical and textural aspects of soil crusting adopted the same PRLeB. With the first formalization, 15% and 39% of the soils in Greece were characterized as very low and low susceptible to soil crusting respectively. With the second formalization 58 – 63% of the soils were characterized by no and 5 – 7% by very low crusting susceptibility. Current work explored two fundamentally different facets of the soil crusting problem. The first formalization, which can be expressed as the soil susceptibility to crusting, considers crusting as an inherent soil process. The second formalization, expressed as soil crusting susceptibility encounters crusting as a complex phenomenon involving natural but not anthropogenic factors. The study indicated that vegetation and seasonality are important factors in the map-based assessment of the observable soil crusting phenomenon. Also, it was highlighted that the unambiguous problem specification is a critical aspect for complex problem assessment and communication, particularly within an interdisciplinary context

The Effect of Land Management Practices on Soil Quality Indicators in Crete

The effects of four main practices tillage versus no-tillage, and intensive grazing versus extensive grazing, applied in characteristic agricultural and grazing lands of Crete Island were evaluated in situ using nine soil quality indicators. The following nine representative indicators of soil quality were evaluated using the rapid visual assessment methodology adopted at European level in the context of the EU research project iSQAPER: susceptibility to water and wind erosion, surface ponding (under cropping), formation of tillage pan, soil color, soil porosity, soil structure, susceptibility to slaking, infiltration rate, and biodiversity status. These indicators were measured in 48 agricultural field-plots to adequately represent the four above-mentioned practices and the different types of geomorphological patterns existing in the area. Additionally, 38 agricultural fields were sampled in the topsoil to assess cultivation practices (tillage, no-tillage) on soil organic carbon, cation exchange capacity, exchangeable potassium, available phosphorous, and soil aggregate stability. Based on the indicators rating methodology, the appropriate statistical tests were applied and the soils under different managements were characterized in terms of their potential quality and their general agricultural value. The obtained data showed that in agricultural areas, significant differences were detected between tillage and no-tillage management practices for the indicators of soil structure and consistency and infiltration rate. In grazing land, significant differences were found for the soil quality indicators of susceptibility to erosion and infiltration rate for the corresponding practices of intensive and extensive grazing. Organic carbon content, exchangeable potassium content and aggregate stability were greatly affected in tillage versus no-tillage management practices