Issue 3 [September]( Issue on Water Resources, Hydrology and Hydraulics )Editorial Decision support for agricultural water managementPanagopoulos Y., Makropoulos C. and Mimikou M., Pages:255-263 DOI: https://doi.org/10.30955/gnj.000887Paper Topic: General Issue: Issue 3Get Full Paper AbstractIrrigation water use is the major pressure limiting the availability of fresh water resources in the Mediterranean. Efficient irrigation scheduling programs (IRSPs) are able to reduce water consumption; however, their selection and placement in large agricultural landscapes depend on location specific characteristics and economic indicators. Towards this end, a novel and efficient Decision Support Tool (DST) is developed in MATLAB-programming, able to assess the effectiveness of different IRSPs in reducing total agricultural water use at the catchment scale along with their impact on crop yields. The DST integrates a look-up table with data on irrigation water amounts and crop yields at different locations within a catchment, populated by a hydrological and crop growth estimator: the process-based SWAT model, into a multi-objective Genetic Algorithm, which serves as the optimization engine for the allocation of measures across the agricultural land. The optimization scheme leads rapidly to the optimal trade-off frontier between the conflicting objectives providing spatial allocations of IRSPs. The tool was implemented in the Ali Efenti catchment demonstrating optimal solutions that could save more than 10% of water by reducing cotton yields less than 5% from the baseline. The study highlights the potential of the tool to assist in the development of cost-effective water saving plans at the catchment level in order to reduce the risk of desertification in intensively cultivated areas. Assessing Alternative Water Resources Management Scenarios in Islands of the Aegean Archipelago, GreeceKaravitis C.A., Skondras N.A., Manoli E. and Assimacopoulos D., Pages:264-275 DOI: https://doi.org/10.30955/gnj.000886Paper Topic: General Issue: Issue 3Get Full Paper AbstractThis effort discusses and evaluates alternative water management options to alleviate water stress and meet water needs in insular entities of the Aegean Archipelago, within the framework set by the principles of Integrated Water Resources Management (IWRM) and of the Water Framework Directive 2000/60/EC. Options are presented and assessed to determine integrated applicable strategies reflecting technical, economic, social and environmental constraints. The assessment is based on the application of the WaterStrategyMan Decision Support System (WSM DSS), developed under the Fifth Framework Programme, and is performed for six islands of the region. Results emphasize the need to understand the interconnections between social, technical, economic, and environmental problems in order to reach integrated solutions. In the dynamic context of current societies, pragmatic policy initiatives are needed to improve the means of preventing and addressing such issues, as well as new institutional structures to handle appropriately competing and conflicting water demands and development objectives. An environmental approach for the management and protextion of heavily irrigated regionsStathatou P.G., Tsoukala V.K., Papadopoulou M.P., Stamou A., Spiliotopoulou N., Theochari C.and Papagrigoriou S., Pages:276-283 DOI: https://doi.org/10.30955/gnj.000880Paper Topic: General Issue: Issue 3Get Full Paper AbstractIn this paper the results of a preliminary study that investigates water footprint (WF) concept, as a useful tool to address water management problems in cultivated areas are presented. The two basic methodologies reported in the literature, their applicability, benefits and challenges were previously analyzed and evaluated by Tsoukala et al. (2011). A WF calculation for the crops of Messara valley in Crete is presented, so as to examine its contribution to achieving effective agricultural policies. Messara is one of the most important agricultural regions in Greece that faces serious problems in order to meet crop irrigation demand. The conclusions drawn from this analysis showed that WF can provide a transparent framework for the identification of potentially optimal alternatives for efficient water use at river basin catchment level. Estimating flood inundation and the consequent economic losses in the Koiliaris river basin in Crete, GreeceVozinaki A.-E.K., Kourgialas N.N. and Karatzas G.P., Pages:284-293 DOI: https://doi.org/10.30955/gnj.000875Paper Topic: General Issue: Issue 3Get Full Paper AbstractLocal communities may experience flood events with devastating damages and economic losses. This work presents the application of an integrated method for flood loss estimation at the watershed level. The one-dimensional hydraulic model MIKE 11 was used to simulate the physical process of a flood event in a river channel and its floodplains. Flood parameters such as flood extent, floodplain water depth and flood duration were estimated. The parameter values obtained from the simulation were used for the estimation of flood loss. A grid-based mathematical model taking into account land use in the study area was used for this purpose. Such an econometric model is capable of determining flood-prone areas as well as estimating the economic losses associated with a flood event. This integrated methodology was applied to the Koiliaris River Basin in Crete, Greece. The impact of forest fires on the vulnerability of peri-urban catchments to flood events: The case of the Easter Attica Region, GreecePapathanasiou C., Alonistioti D., Kasella A., Makropoulos C. and Mimikou M., Pages:294-302 DOI: https://doi.org/10.30955/gnj.000877Paper Topic: General Issue: Issue 3Get Full Paper AbstractFloods are natural disasters that pose a direct threat to human life and often cause significant economic loss. River floods are caused by heavy and/or prolonged rainfall, causing rivers and streams to overflow and sometimes also burst dams or levees. Forest fires increase the risk factor to which humans and properties are exposed during flood events, by intensifying and accelerating the peak volume of the overflow water. Wildfires alter significantly the geomorphological characteristics of a river basin, thus affecting both directly and indirectly its hydrological behavior. A forest fire, followed by a rainfall event, may cause a significant flood downstream. This paper presents a hydrological analysis of the eastern Attica region, which is performed both prior to and after forest fire events, in order to assess the change in the consequent flood risk. The study area is the eastern part of the greater Athens area in Attica (Greece). This is a peri-urban area experiencing rapid urban growth, and its hydrometeorological conditions are being monitored though a dense hydrometeorological network for the past 10 years. A fire model is set up to simulate the characteristics of the development of three hypothetical fire events of low, medium and high severity accordingly. The parameters that affect fire intensity and rate of spread (e.g. topographic factors such as slope steepness, elevation, aspect, and configuration of land) are taken into consideration and the temporal and spatial distribution of a forest fire is studied. Of additional interest in this study is the fact that a recent forest fire event devastated a significant part of its northern, mountainous area and the consequences of this event are further examined. A detailed simulation of the three hypothetical fire scenarios and the real fire event is performed and the outcomes of the analysis are used as an input in a rainfall – runoff model that allows for an enhanced hydrological study of the affected area. Land use changes and geomorphological and hydrological alterations as a result of the fire event are taken into consideration during a post-fire hydrological analysis, which eventually demonstrates the impact of fire on the hydrological response of the study area. This impact is assessed by means of application of a methodological framework for the estimation of post-fire values for three hydrological parameters (CN, initial abstraction and lag time) and the paper concludes that the fire impact has rendered the downstream areas more prone to floods. Wildfires impact on hydrological response – the case of Lykorrema experimental watershed, GreeceSoulis K.X., Dercas N. and Valiantzas J.D., Pages:303-310 DOI: https://doi.org/10.30955/gnj.000876Paper Topic: General Issue: Issue 3Get Full Paper AbstractOne of the issues that have recently attracted increased attention from the hydrologic community is the impact of forest fires on the hydrological response of the once vegetated areas. This study presents the investigation of wildfires impact on the hydrological response of the small scale experimental watershed of Lykorrema stream, which is located in the east side of Penteli Mountain, Attica, Greece. In the recent years, the watershed was affected by two wildfires in August 1995 and in August 2009. The effect of the August 1995 wildfire on the peak runoff was investigated in a previous study, in which an increment of 10 times in peak runoff was observed. This paper presents the results of an analysis concerning the impact of the second wildfire on the watershed’s hydrological response based on the available detailed spatial physical and hydro-meteorological data. The results obtained highlight the considerable impact of forest fire on the watersheds hydrological response. An increment in the direct runoff depths and the peak flow rates as much as 230% and 850% respectively was observed during the first two years of the post-fire period. An extreme analysis for the 2010 precipitation event at the South of Saskatchewan PrairieChun K.P. and Wheater H.S., Pages:311-324 DOI: https://doi.org/10.30955/gnj.000890Paper Topic: General Issue: Issue 3Get Full Paper AbstractAfter a prolonged drought period in the early 2000s, the Canadian prairie experienced a remarkably wet year in 2010. Five stations near the edge of the Saskatchewan boreal forest recorded historically high cumulative precipitation (from April to September). The exceptional wet year causes the public concerns on flood controls and land use management in the region. Using the Canadian National Climate Data Achieve, characteristics of six-month cumulative precipitation sums over Saskatchewan prairie are investigated by the Generalised Extreme Value (GEV) Theory. Based on the unconstrained GEV distribution, the 2010 event is outside the estimated 95% confidence intervals for the five Canadian prairie stations. On the contrary, the exceptional high 2010 cumulative perception sums for the five stations are still bounded by the estimated confidence bounds if the GEV distribution is constrained to the Gumbel distribution (i.e. setting the shape factor of the GEV distribution to be zero). These results demonstrate that the classical extreme analysis is useful for planning unprecedented extreme events in the Canadian Prairie, if the GEV distribution is constrained to the Gumbel distribution with the estimated uncertainty bounds based on the order statistics. Using an informational entropy-based metric as a diagnostic of flow duration to drive model parameter identificationPechlivanidis I.G., Jackson B.M., McMillan H.K. and Gupta H.V., Pages:325-334 DOI: https://doi.org/10.30955/gnj.000879Paper Topic: General Issue: Issue 3Get Full Paper AbstractCalibration of rainfall-runoff models is made complicated by uncertainties in data, and by the arbitrary emphasis placed on various magnitudes of the model residuals by most traditional measures of fit. Current research highlights the importance of driving model identification by assimilating information from the data. In this paper, we evaluate the potential use of an entropybased measure as an objective function or as a model diagnostic in hydrological modelling, with particular interest in providing an appropriate quantitative measure of fit to the flow duration curve (FDC). The proposed Conditioned Entropy Difference (CED) metric is capable of characterising the information in the flow frequency distribution and thereby constrain the model calibration to respect this distributional information. Four years of hourly data from the 46.6 km2 Mahurangi catchment, NZ, are used to calibrate the 6-parameter Probability Distributed Moisture model. Results are analysed using three measures: the proposed entropy-based measure, the Nash-Sutcliffe (NSE), and the recently proposed Kling-Gupta efficiency (KGE). We also examine a conditioned entropy metric that trades-off and reweights different segments of the FDC to drive model calibration in a way that is based on modelling objectives. Overall, the entropy-based measure results in good performance in terms of NSE but poor performance in terms of KGE. This entropy measure is strongly sensitive to the shape of the flow distribution and is, from some viewpoints, the single best descriptor of the FDC. By conditioning entropy to respect multiple segments of the FDC, we can reweight entropy to respect those parts of the flow distribution of most interest to the modelling application. This approach constrains the behavioural parameter space so as to better identify parameters that represent both the “fast” and “slow” runoff processes. Use of this importance-weighted, conditioned entropy metric can constrain high flow predictions equally well as the NSE and KGE, while simultaneously providing wellconstrained low flow predictions that the NSE or KGE are unable to achieve. Sensitivity analysis of different evapotranspiration methods using a new sensitivity coefficientAmbas V.Th. and Baltas E., Pages:335-343 DOI: https://doi.org/10.30955/gnj.000882Paper Topic: General Issue: Issue 3Get Full Paper AbstractThe estimation of evapotranspiration is essential in water resources management. Among a group of methods, the Penman–Monteith has been commonly applied to calculate reference evapotranspiration as this method has been also recommended by the Food and Agriculture Organization of the U.N. (FAO). Other methods widely used are: the FAO 24 Penman, the modified Blaney and Criddle, the FAO 24 Makkink, and the Hargreaves. Sensitivity analysis is required to gain a better understanding of the meteorological systems; particularly to indicate the physical meaning of each meteorological parameter used in the estimation of the reference evapotranspiration. Several dimensionless sensitivity coefficients have been proposed, based on the partial derivative of the dependent variable (reference evapotranspiration) to the independent variables (meteorological variables). In this paper, a new sensitivity coefficient is proposed to drive sensitivity analysis of the evapotranspiration methods. The new sensitivity coefficient uses the partial derivative and the standard deviation of each independent variable. The meteorological variables, whose influence has been examined, are all the necessary meteorological parameters for the calculation of reference evapotranspiration, such as temperature, solar radiation, wind speed and relative humidity for each method. Data from the automatic meteorological station of Aminteo in the Prefecture of Florina, Western Macedonia, were used. The sensitivity coefficients were calculated for each month, year and irrigation period. The comparison of the sensitivity coefficients is performed for the month of water peak demand (July), the irrigation period and the year for each evapotranspiration method. Results show that the influence of the variables to evapotranspiration is not the same for each period, and also the order that the variables influence evapotranspiration is changing. A comparison between the five evapotranspiration methods shows that solar radiation and temperature are the main parameters that affect evapotranspiration, while relative humidity and wind speed are not so important for the calculation of evapotranspiration. Systematic approach for ungaged basins’ discharge determination in Western Peloponnese, GreeceDaniil Ε.Ι., Michas S.N., Nikolaou K. and Lazaridis L.S., Pages:344-353 DOI: https://doi.org/10.30955/gnj.000878Paper Topic: General Issue: Issue 3Get Full Paper AbstractDetermining peak flows for ungaged areas is difficult and involves high uncertainty. Advanced computer capabilities provided by geographical information systems and hydrologic modeling software are used for detailed determination of the parameters involved, both for simple methods as the rational method and more detailed ones as the application of synthetic hydrographs. For the determination of the runoff coefficients and other runoff parameters, digital elevation models were combined with geologic and land use maps in order to extract morphologic and other distributed parameters with the use of GIS for computation of watershed runoff. The discharges were determined by the rational method, the Fuller’s formula and a hydrologic model using synthetic hydrographs according to SCS. A dependable estimate of the design discharge is necessary both for demarcation studies of watercourses and the assessment and management of flood risks according to the guidelines of Directive 2007/60/EC. In this paper a case study in Western Peloponnese is presented. Area specific fitted equations relating the drainage area to the peak flows were developed, that can be used in adjacent regions. The results of the hydrologic studies performed for many geographical units of the new Patra - Pyrgos - Tsakona highway, presently under construction, are analyzed and presented. Results of the rational method and modeling with the HEC-HMS system using SCS hydrographs were compared. Transverse drainage works, where the motorway crosses watercourses, were designed with the 50- yr design discharges determined by the hydrologic model with the use of synthetic hydrographs, lag time and CN, depending on land use, geology and soil cover, determined according to SCS. In the case of bridges with piers the corresponding 100-yr values were used. Differences between the rational method and the hydrologic model are not significant in most cases. Pronounced differences were noticed only in the combined presence of high water transmissivity soils and forest cover. Regional equations were developed for use. In the basins used there are no areas with major urban development or basins with control structures. The equations refer to the 50-yr design flood and can be used in any further computation that may be required in the vicinity without further hydrologic analysis. Comparison with other studies shows good agreement and with similar equations from other projects resemblance. Pages1 2 next › last »