Main Sub-basins Research Articles

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.

The Influence of the Spatial Scale on the Fishery Landings-SST Relationship

Possible effects of the spatial scale of analysis on the relationship between fishery landings and the water temperature in the Mediterranean Sea have been investigated using the FAO capture database (1970-2010). The analysis was performed by dividing species in three thermal affinity categories: cold, temperate and hot species. Results showed significant changes in fishery landings composition during the last four decades, in terms of the relative contribution of cold, temperate and hot species to landings; moreover, the presence of a strong influence of water warming in determining the landings temporal pattern has been confirmed. This relationship, however, resulted to be not homogenous across the tested spatial scales (entire Mediterranean basin, three main sub-basins, eight FAO areas). The best models (based on the Akaike Information Criterion), were the ones fitted at the finer spatial definition (i.e. the eight FAO areas) for all the three thermal affinity categories. The recorded relationship showed clear differences in terms of direction, depending on both areas and thermal affinity groups. Cold species showed a negative relationship with the increasing water temperature in all the FAO areas, being partially replaced by temperate ones, with the exception of the Adriatic and Black Sea (the coldest areas in the Mediterranean basin), where a moderate increase in the water temperature is still favoring the cold affinity group. This kind of results could be useful within the context of the management plans definition, within a context of climate changes.

Geoinformatics application for assessing the morphometric characteristics’ effect on hydrological response at watershed (case study of Wadi Qanunah, Saudi Arabia)

This study deals with the evaluation and inundation of flash flood hazard in the ungauged Wadi Qanunah basin depending on detail morphometric characteristics of Qanunah basin and its sub-basins. Data for this study were depending on ASTER data for digital elevation model (DEM) with 30-m resolution, topographic map (1:50,000) and geological maps (1,250,000) which were verified during the fieldwork for evaluation of linear, areal, shape, and relief aspects of morphometric parameters. About 39 morphometric parameters were measured and calculated and interlinked to produce nine effective parameters to evaluate the flash flood hazard degree of the Wadi Qanunah basin. This study examined the physiographic features of the study basin with emphasis on their implication for hydrologic processes through the integration analysis between physiographic features and geographical information system (GIS) techniques. Wadi Qanunah basin was classified into 13 sub-basins, and according to their hazards degree, it is classified into three groups: basins of high hazard degree as for Wadi Qanunah sub-basin, basins of medium hazard degree as for Wadi Al Hafyan and Baydan 1 sub-basins, and basins of low hazard degree as for the rest of the sub-basins. Watershed Modeling System (WMS) and Hydrologic Engineering Center-Hydrologic Modeling System software (HEC-HMS) were applied to generate the hydrograph of the two main sub-basins of Wadi Qanunah and Wadi Khatm Al Jurrah. The results of the model for maximum daily rainfall events of a total of 65, 79, 97, 110, and 123 mm with return periods of 5, 10, 25, 50, and 100 years, respectively. Total volume of discharge of Wadi Qanunah sub-basins ranges from 66 × 106 to 138 × 106 m3, while for Wadi Khatm Al Jurrah sub-basin, it ranges from 11 × 106 to 24 × 106 m3 at return periods from 5 to 10 years, respectively.

Investigating climate change using AK stationarity test in the Lake Urmia basin

Augmented Dickey-Fuller (ADF) and Kwaitowski-Phillips-Schmidt-Shin (KPSS) test are the most employed tests to test stationarity. Because of the different null hypothesis of these two tests, their power varies in different stationarity cases. The problem arises when the results of ADF and KPSS test are against each other for the same time series. In the current study, the power of these two statistical tests is investigated with a set of artificial hydrological time series. Results indicate that both ADF and KPSS test are unable to detect second order stationarity and KPSS is sensitive to outliers. Then, sequent combination of ADF and KPSS introduced as AK test. The AK test is able to identify first order stationarity, first order non-stationarity (unit root) and long memory. Although some non-stationaries are observed in precipitation, evaporation and stream flow time series in eight main sub-basins of Lake Urmia, but there are no strong evidence to suggest climate change incidence.

Post-depositional history of the Miocene Gorgoglione Formation (southern Apennines, Italy): inferences from mineralogical and structural analyses

Abstract The Gorgoglione Formation represents the infill of a thrust-top basin, which records the tectonic evolution of the southern Apennines (Italy) since Upper Miocene times. The Upper Miocene basin was divided into two main sub-basins, showing both about NNW-SSW elongation. During ongoing contractional deformation, the Gorgoglione basin was incorporated into the allochthonous units of the Apennine fold-and-thrust belt, as outlined by the emplacement of thrust sheets of internal provenance (Sicilide Unit) and by the development of two main generations of tight to open folds. In this work, the modalities of deformation associated to the incorporation of the Gorgoglione Formation into the fold-and-thrust belt has been documented by means of mineralogical and structural analyses. Mineralogical data show that, in the northeastern sub-basin of the Gorgoglione Formation, the illite content and the order of illite/smectite mixed layer increase near the contact with the overlaying Sicilide Unit. These data are hence used to estimate the relative tectonic load produced by thrusting of the aforementioned tectonic unit. Structural data are consistent with tight, NNW-trending, meso-scale folds particularly frequent in the upper pelitic/arenaceous portion of the Gorgoglione Formation. Within these folded pelitic levels, a well-developed axial-plane foliation, and an ordered I/S (R1 and R3) with higher illite content, is documented. Instead, other folds developed far away from the Sicilide klippen show an incipient axial-plane foliation and a random I/S (R0) with lower illite amount is found in pelites. The data suggest that the eastern sub-basin of the Gorgoglione Formation underwent variable tectonic load, increasing from E to W, as well as deformation produced by thrusting of Sicilide sheet. The mineralogical data also indicate that illitization process is favoured for the high availability of potassium due to the dissolution of k-feldspar. High potassium availability affects the samples subjected to the highest diagenetic degree, characterized by kaolinite illitization process.

Geophysical Contribution in the Characterization of Deep Water Tables Geometry (Sidi Bouzid, Central Tunisia)

Geophysical data combined with geological and hydrogeological data were analyzed to characterize the geometry of Oued El Hajel and Ouled Asker deep water tables (Sidi Bouzid). The obtained results allowed refining the geostructural schema by highlighting the individualization of the NE-SW underground convexity of Ouled Asker and the anticline of axis Es Souda-Hmaeima and Ezaouia on either sides of two hydrogeological thresholds. The geometrical analysis determined the spatial extension of Ouled Asker and Oued El Hajel subbasins. The seismic cartography of semideep and deep reservoirs (Oligo-Miocene; Eocene and upper Cretaceous) associated with the main subbasins contributed to proposing hydrogeological prospect zones for a rationalized groundwater exploitation.

Reacciones en la precipitación ante oscilaciones oceánicas en sus temperaturas superficiales: depresión tectónica central, Costa Rica

<p>Se analiza la influencia del evento el ENOS en la precipitación de la Depresión Tectónica<br />Central de Costa Rica, encontrándose que dicha respuesta es diferente, dada la diferencia<br />de temperaturas superficiales entre océano Pacífico y Atlántico. Estos pueden contribuir en<br />mayor o menor grado en la producción de masas de aire cargadas de humedad que puedan<br />llegar hasta esta región. Similarmente, dicha región presenta irregularidades geomorfológicas<br />en las dos principales sub-cuencas Virilla y Grande de San Ramón que contribuyen aún más<br />con las diferencias en los niveles de precipitación, siendo esta reducción en la precipitación<br />aún mayor en la sub-cuenca del río Grande de San Ramón.</p>

Water storage changes and climate variability within the Nile Basin between 2002 and 2011

Understanding water storage changes within the Nile’s main sub-basins and the related impacts of climate variability is an essential step in managing its water resources. The Gravity Recovery And Climate Experiment (GRACE) satellite mission provides a unique opportunity to monitor changes in total water storage (TWS) of large river basins such as the Nile. Use of GRACE-TWS changes for monitoring the Nile is, however, difficult since stronger TWS signals over the Lake Victoria Basin (LVB) and the Red Sea obscure those from smaller sub-basins making their analysis difficult to undertake. To mitigate this problem, this study employed Independent Component Analysis (ICA) to extract statistically independent TWS patterns over the sub-basins from GRACE and the Global Land Data Assimilation System (GLDAS) model. Monthly precipitation from the Tropical Rainfall Measuring Mission (TRMM) over the entire Nile Basin are also analysed by ICA. Such extraction enables an in-depth analysis of water storage changes within each sub-basin and provides a tool for assessing the influence of anthropogenic as well as climate variability caused by large scale ocean–atmosphere interactions such as the El Niño Southern Oscillation (ENSO) and the Indian Ocean Dipole (IOD). Our results indicate that LVB experienced effects of both anthropogenic and climate variability (i.e., a correlation of 0.56 between TWS changes and IOD at 95% confidence level) during the study period 2002–2011, with a sharp drop in rainfall between November and December 2010, the lowest during the entire study period, and coinciding with the drought that affected the Greater Horn of Africa. Ethiopian Highlands (EH) generally exhibited a declining trend in the annual rainfall over the study period, which worsened during 2007–2010, possibly contributing to the 2011 drought over GHA. A correlation of 0.56 was found between ENSO and TWS changes over EH indicating ENSO’s dominant influence. TWS changes over Bar-el-Ghazal experienced mixed increase–decrease, with ENSO being the dominant climate variability in the region during the study period. A remarkable signal is noticed over the Lake Nasser region indicating the possibility of the region losing water not only through evaporation, but also possibly through over extraction from wells in the Western Plateau (Nubian aquifer).

Geometría del basamento y espesores sedimentarios del lago Fagnano (Tierra del Fuego).

Lago Fagnano, an E-W elongated basin located in the central part of Isla Grande de Tierra del Fuego, occupies a structural depression originated along a segment of the Magallanes-Fagnano fault system. Its evolution was mostly conditioned by tectonic processes, and later was affected by glacial and glacio-lacustrine depositional events. New high-resolution single-channel seismic data, integrated with previous seismic profiles, and geological information acquired in the surroundings of the Lago Fagnano, allows us reconstructing the basement surface of the lake, and the geometry, distribution, and thickness of the glacial and glacio-lacustrine sequences. We recognized three main sub-basins within the Lago Fagnano: 1. a medium-size (ca. 21x5 km), deep (373 m), and asymmetric basin to the east; 2. an E-W trending (44x3 km), shallower (150 m) central sub-basin; and 3. a smaller (3.5x1.3 km), shallow (128 m) sub-basin to the west. The isopach sediment map shows that the most pronounced deposition occurred along the E-W axis of the lake, with a gradual increase in thickness towards east (from 100 to 150 m). The glacial deposits are widespread along the basin. The lacustrine sediments are preferentially localized along the E-W axis of the lake filling topographic lows. The shape of the sub-basins and their location in relation with the Magallanes-Fagnano fault system, along with the distribution, geometry, and thickness of the sedimentary units, show that the general morphology of the Lago Fagnano was mostly controlled by pre-existing and syntectonic features. Based on the structural data observed in the outcrops around the Lago Fagnano and the geophysical data, we proposed that the lake is composed by 4 amalgamated pull-apart sub-basins.

Application of the migration models implemented in the decision system MOIRA-PLUS to assess the long term behaviour of 137Cs in water and fish of the Baltic Sea

This work presents and discusses the results of an application of the contaminant migration models implemented in the decision support system MOIRA-PLUS to simulate the time behaviour of the concentrations of 137Cs of Chernobyl origin in water and fish of the Baltic Sea. The results of the models were compared with the extensive sets of highly reliable empirical data of radionuclide contamination available from international databases and covering a period of, approximately, twenty years. The model application involved three main phases: a) the customisation performed by using hydrological, morphometric and water circulation data obtained from the literature; b) a blind test of the model results, in the sense that the models made use of default values of the migration parameters to predict the dynamics of the contaminant in the environmental components; and c) the adjustment of the model parameter values to improve the agreement of the predictions with the empirical data. The results of the blind test showed that the models successfully predicted the empirical contamination values within the expected range of uncertainty of the predictions (confidence level at 68% of approximately a factor 2). The parameter adjustment can be helpful for the assessment of the fluxes of water circulating among the main sub-basins of the Baltic Sea, substantiating the usefulness of radionuclides to trace the movement of masses of water in seas.

Seasonal characteristics of size-fractionated phytoplankton community and fate of photosynthesized carbon in a sub-Antarctic area (Straits of Magellan)

Phytoplankton community size drives the rates of biogenic carbon and the overall structure and dynamics of the marine pelagic food web. The Straits of Magellan, an inland passage between the Pacific and Atlantic Oceans, can be separated into three main sub-basins: the western-Pacific, the V-shaped central zone, and the eastern-Atlantic. To provide insights into the food structure of the phytoplankton community, size-fractionated chlorophyll a concentration and primary production rates were measured across the three sectors of the Magellan Straits in four periods between 1989 and 1995 in the Straits. Phytoplanktonic biomass and production ratios provided ecological insights into the food web structure, including the relevance of grazing in its largest fraction.The micro-phytoplanktonic fraction (>10μm) in the Pacific sub-basin is significantly less abundant than in the Central and Atlantic ones. Conversely, the lowest abundance of the pico-fraction (<2.0μm) is encountered in the Atlantic sub-basin. The observed patterns agree with the diffusion of smaller-size fractions from the western towards the easternmost sector of the Straits, and suggest that the largest phytoplankton tend to accumulate in the inner stretch of the Straits, being constrained by a clockwise gyre generated by tidal phases or partially spilling out into the Atlantic sector. The most active grazing activities occur in the Central sub-basin during the spring bloom and appear even stronger in summer.Our results pinpoint also that the basic levels of the planktonic food web rely on the nanophytoplankton (10–2μm) fraction, which is the main contributor to the continuum multivorous food web. When external energy (e.g. nutrient pulses from land freshwater and water mixing) enters the system, the structure of the plankton in the Straits shifts towards the herbivorous food web and is characterized by the presence of large-size diatoms. This dynamics keeps the system in a persistent mesotrophic state, featuring a lower trophic status than the Antarctic ones but much higher than that of oligotrophic temperate areas.

Runoff Estimation by Machine Learning Methods and Application to the Euphrates Basin in Turkey

AbstractMachine learning (ML) techniques have been popular data-driven approaches for hydrological studies during the last few decades owing to their capability to identify complex nonlinear relationships between input and output data without the requirement for physical understanding of the system. This paper aims to predict river flows using various ML methods [feed forward neural network (FFNN), adaptive neuro fuzzy inference system (ANFIS), and genetic programming (GP)] and also a non-ML method (multiple linear regression) in the Euphrates Basin in Turkey. Infilling the missing data in the runoff record of the selected stations in Euphrates Basin is also an objective of this study. The ML methods were applied to the three main sub-basins of the Euphrates Basin, namely the Upper, Middle, and Lower Euphrates Basins. ANFIS and FFNN methods were the most successful ML methods for runoff estimation in the Upper and Lower Euphrates Basins, whereas GP and ANFIS models were the best ones in the Middle Euphrat...

Hydrological response to climate variability at different time scales: A study in the Ebro basin

Summary In this study we analyzed the response of monthly runoff to precedent climatic conditions at temporal scales of 1–48 months in 88 catchments of the Ebro basin (northeast Spain). The standardized precipitation evapotranspiration index (SPEI) was used to summarize the climatic conditions at different time scales, and was correlated with the standardized streamflow index (SSI) calculated at the mouth of each catchment. The Ebro basin encompasses a gradient from Atlantic to Mediterranean climates, and has remarkable complexity in topography, geology and land cover. The basin is highly regulated by dams, which were built to produce hydropower and supply water for agriculture. These characteristics explain why sub-basins of the Ebro River basin respond in differing ways to precedent climatic conditions. Three main sub-basin groups were distinguished on the basis of the correlation of their streamflow responses to different time scales of the SPEI: (1) sub-basins correlated with short SPEI time scales (2–4 months), which generally corresponded to unregulated headwater areas; (2) sub-basins correlated with long SPEI time scales (10–20 months), where groundwater reserves play a major hydrological role; and (3) sub-basins correlated with medium SPEI time scales (6–10 months). The latter occur in the lower sectors of the Ebro basin and its tributaries, which receive river flows from the other two sub-basins, and where dam regulation has a significant influence on the hydrological characteristics. In addition to the three main sub-basin groups, other streamflow responses associated with seasonal factors were identified, particularly those related to snowpack and the various management strategies applied to reservoirs.

Palynostratigraphy and age correlation of subsurface strata within the sub-basins in Singrauli Gondwana Basin, India

In the study area, changes in the facies of sediments and spores-pollen content appear to be all causally linked with the depositional set-up. Here, the qualitative and quantitative changes observed in the spores-pollen assemblages have led to recognize 10 Assemblage-zones representing from that earliest Permian in the Talchir Formation to that latest Late Triassic in the Parsora Formation. These spores-pollen assemblages are obtained from the wider parts in the Singrauli Gondwana Basin that includes (i) Moher sub-basin (boreholes SSM-1 and 2), and (ii) Singrauli main sub-basin (boreholes SMJS-2, 3 and SMBS-1). The progressively changing spores-pollen content infer the hiatuses of varied magnitude in the sedimentary sequences during the extended time interval of Permian and Triassic.

On the surface circulation of the Levantine sub-basin derived from Lagrangian drifters and satellite altimetry data

The surface currents of the Levantine sub-basin (Mediterranean Sea) are described using 18 years (1992–2010) of drifter data and satellite-derived sea level anomalies. The combination of drifter and satellite data allowed to estimate maps of surface geostrophic circulation and to obtain more accurate pseudo-Eulerian velocity statistics for different time periods. Seasonal and interannual variability of surface currents are investigated with particular focus on the main sub-basin eddies of the eastern Levantine. The mean velocity field depicts the typical patterns of the along-slope and offshore currents and outlines the sub-regions where eddies are generated recurrently (west Egyptian coast, Ierapetra, Mersa-Matruh, south-west of Cyprus, Israel–Lebanon coast, Latakia) or persist steadily (Rhodes Gyre). Highly variable and energetic currents are observed between the Ierapetra and Mersa-Matruh regions, as the result of the interaction of the Mid-Mediterranean Jet meandering in between, and interacting with, the eddies generated by the instability of the coastal current. Seasonal pseudo-Eulerian maps show the current field stronger in summer and weaker in winter, mainly in the western Levantine and in the Cyprus–Syria Passage. The Shikmona Eddy displays a periodic nature with higher intensities during the cold months and an enhanced activity in the period 1998–2005. The Cyprus Eddy has a less periodic nature, characterised by events of high activity and periods in which it dominates as a single enlarged eddy in the southeast Levantine, eventually including the Shikmona Eddy. The Latakia Eddy is mainly cyclonic with higher intensities in summer and fall; occasional weekly or monthly inversions of circulation from cyclonic to anticyclonic are triggered by the interaction between the MMJ and the northward coastal meandering current.

流域"源-汇"景观格局变化及其对磷污染负荷的影响——以天津于桥水库流域为例

The relationship between source-sink landscape pattern and phosphorus pollution in Yuqiao watershed(Tianjin) was revealed by use of digital elevation model and phosphorus pollution spatial simulation model on the basis of remote sensing(RS) images interpretation.DEM data at the scale of 1∶50000 were used to extract surface features,identify flow direction,calculate flow accumulation and extract river network in the whole basin using the hydrology module in the ArcGIS spatial analyst tool.Maximum like hood classification algorithm was used to extract land cover information for Yuqiao watershed from the TM images of 1999 and 2009 on which basis landscape change from 1999 to 2009 was statistically analyzed.Spatial distribution of phosphorus pollution in Yuqiao watershed under different landscape patterns were simulated by scenario approach.It is found that the area ratio of sink landscape types of forest,shrub and grass decreased 18.44% whereas that of source landscape types of cultivated land,orchard,built-up increased 12.34%.For the main sub-basins in Yuqiao watershed,namely,Li River,Sha River and Lin River,the area ratio of source landscape types to sink landscape types were 2.81∶1,1.82∶1 and 0.85∶1,respectively in 2009.The total phosphorus pollution of Yuqiao watershed increased significantly from 1.00(kg/km2) up to 1.12(kg/km2) from 1999 to 2009 when the total phosphorus pollution of source landscape has increased 51.5% from 0.98(kg/km2) to 1.49(kg/km2).Significant spatial heterogeneity of phosphorus pollution existed among the three sub-basins with the total phosphorus load in Lin River,Sha River and Li River being 1.26(kg/km2),1.14(kg/km2) and 1.10(kg/km2),respectively.In sum,there were significant temporal and spatial heterogeneity between source-sink landscape pattern and phosphorus pollution in Yuqiao watershed.

Water Transport and Water Retention in Five Connected Subbasins in the Baltic Sea—Simulations using a General Mass-Balance Modeling Approach for Salt and Substances

This work presents monthly budgets for water and salt in the Baltic Sea and its five main subbasins, the Baltic Proper, the Bothnian Sea, the Bothnian Bay, the Gulf of Finland, and the Gulf of Riga. This process-based mass-balance model uses empirical data (from Helsinki Commission [HELCOM]) for the period 1997 to 2005. Previous models of this kind generally have used water-temperature data to differentiate between different water layers. This model (CoastMab) uses sedimentological criteria related to the theoretical wave base to differentiate between the surface-water layer and lower vertical layers. CoastMab stems from a model development in aquatic radioecology, and it has been previously validated for many different substances (radionuclides, metals, nutrients, suspended particulate matter, and salt) in lakes and relatively small coastal areas but not for such a large and complex system of interconnected basins as the Baltic Sea. New morphometric data for the Baltic Sea and the defined subbasins and new hypsographic and volume curves based on digitized bathymetric data are also presented and used in this work. The aim is to present data on the fluxes of water to the system, precipitation, and the theoretical retention times for water and salt in the defined subbasins of the Baltic Sea, since those values provide fundamental information on how the system reacts to changes in, e.g., nutrient loading. The idea with this modeling approach, and the results presented in this work, is that these water fluxes, water retention rates, and the algorithms used to quantify vertical mixing and diffusion among the defined layers should be structured in such a manner that the model also can be used to quantify fluxes of nutrients and toxins. This places certain demands on the structure of the model that may be different from physical oceanographic models, e.g., in quantifying sedimentation, resuspension, mixing, and diffusion, and in the requirements regarding the accessibility of the necessary driving variables.

Comparative chromosomal analyses in species of the genus Pimelodella (Siluriformes, Heptapteridae): occurrence of structural and numerical polymorphisms

Cytogenetic analyses were carried out in fispecies of Pimelodella from the main sub-basins of Up- per Parana River and Paraiba do Sul River. The diploid number ranged from 2n = 46 to 2n = 58 chromosomes, and all populations differed in the karyotype constitution. The presence of supernumerary chromosomes as well as the occurrence of a XX/XY sex chromosome system and heterochromatin polymorphisms were detected. The 18S rDNA FISH confi rmed the presence of single NORs and revealed additional sites on supernumerary chromosomes. The number and location of 5S rDNA sites were variable. Aspects related to the karyotypic evo- lution within the genus are discussed.

Nutrient (N, P, Si) transfers in the subtropical Red River system (China and Vietnam): Modelling and budget of nutrient sources and sinks

The Red River system, which has a population density that varies from 80 to over 1000 inhabitants km −2 in the different sectors of its watershed, is a typical example of a subtropical system experiencing high human pressure. A monthly survey of nutrient concentration was conducted at the outlet of the three main tributaries (Da, Thao and Lo) and at Hanoi on the main branch of the Red River in the upper part of the delta. Samples from headwater streams or irrigation channels draining homogeneous land use classes also were analysed. A GIS database describing the characteristics of the watershed in terms of morphology, climate, land use and population has been established. This served as the basis for implementing the Seneque/Riverstrahler model, which allowed calculation of nutrient transfers and transformations along the whole drainage network of the Red River system. The model was validated using the measured nutrient concentrations obtained during the survey and was used to establish an overall description and a comprehensive budget of nutrient transfer, retention and delivery for the three main sub-basins and the upper part of the delta upstream from Hanoi.

Heat flux through a geothermally heated fluidized bed at the bottom of a lake

Heat fluxes and the underground inflow through a natural fluidized bed within the main sub-basin of Lake Banyoles are studied and parameterized. In the upper part of this fluidized bed, at a depth of about 30 m, the vertical gradients of particle concentration and temperature are very sharply located within an interface a few centimeters thick. Within this interface (lutocline), the depths where the temperature and the concentration gradients are maximum match exactly. On the other hand, the lutocline determines a flat, horizontal surface dividing the water column into a hot, turbid medium at the bottom and clear, colder, bulk water above. Through this interface the flow regime also varies from being laminar just below it, to turbulent due to convective processes developing above it. More precisely, in studied main sub-basin a buoyant plume develops above the lutocline, as a result of the heat flux, and affects the lake's water quality due to particles dragged along by it. In this paper it is proposed to determine the temperature at the depth of maximum gradient within the interface by means of measured temperature profiles, and consider the stationary heat transport equation in the laminar region below it, in order to obtain the water velocity and the heat flux. Heat flux parameterization is given based on a large number of thermal high-resolution profiles, covering six campaigns in different years and seasons. Furthermore, and in consideration of the fact that high-resolution thermal profiles are not always available, some alternative parameterizations for the heat flux are presented based only on the temperature of the fluidized bed and that of the lower hypolimnion.