Identification of appropriate temporal scales of dominant low flow indicators in the Main River, Germany

Models incorporating the appropriate temporal scales of dominant indicators for low flows are assumed to perform better than models with arbitrary selected temporal scales. In this paper, we investigate appropriate temporal scales of dominant low flow indicators: precipitation (P), evapotranspiration (ET) and the standardized groundwater storage index (G). This analysis is done in the context of low flow forecasting with a lead time of 14 days in the Main River, a tributary of the Rhine River, located in Germany. Correlation coefficients (i.e. Pearson, Kendall and Spearman) are used to reveal the appropriate temporal scales of dominant low flow indicators at different time lags between low flows and indicators and different support scales of indicators. The results are presented for lag values and support scales, which result in correlation coefficients between low flows and dominant indicators falling into the maximum 10% percentile range. P has a maximum Spearman correlation coefficient (ρ) of 0.38 (p = 0.95) at a support scale of 336 days and a lag of zero days. ET has a maximum ρ of –0.60 (p = 0.95) at a support scale of 280 days and a lag of 56 days and G has a maximum ρ of 0.69 (p = 0.95) at a support scale of 7 days and a lag of 3 days. The identified appropriate support scales and lags can be used for low flow forecasting with a lead time of 14 days

Hydrologic homogeneous regions using monthly Streamflow in Turkey

Cluster analysis of gauged streamflow records into homogeneous and robust regions is an important tool for the characterization of hydrologic systems. In this paper we applied the hierarchical cluster analysis to the task of objectively classifying streamflow data into regions encompassing similar streamflow patterns over Turkey. The performance of three standardization techniques was also tested, and standardizing by range was found better than standardizing with zero mean and unit variance. Clustering was carried out using Ward’s minimum variance method which became prominent in managing water resources with squared Euclidean dissimilarity measures on 80 streamflow stations. The stations have natural flow regimes where no intensive river regulation had occurred. A general conclusion drawn is that the zones having similar streamflow pattern were not be overlapped well with the conventional climate zones of Turkey; however, they are coherent with the climate zones of Turkey recently redefined by the cluster analysis to total precipitation data as well as homogenous streamflow zones of Turkey determined by the rotated principal component analysis. The regional streamflow information in this study can significantly improve the accuracy of flow predictions in ungauged watersheds

Identification of an appropriate low flow forecast model\ud for the Meuse River

This study investigates the selection of an appropriate low flow forecast model for the Meuse\ud River based on the comparison of output uncertainties of different models. For this purpose, three data\ud driven models have been developed for the Meuse River: a multivariate ARMAX model, a linear regression\ud model and an Artificial Neural Network (ANN) model. The uncertainty in these three models is assumed to\ud be represented by the difference between observed and simulated discharge. The results show that the ANN\ud low flow forecast model with one or two input variables(s) performed slightly better than the other statistical\ud models when forecasting low flows for a lead time of seven days. The approach for the selection of an\ud appropriate low flow forecast model adopted in this study can be used for other lead times and river basins\ud as well

Discussion of “clustering on dissimilarity Representations for detecting mislabelled Seismic signals at Nevado del Ruiz Volcano” by Mauricio Orozco-Alzate, and César Germán Castellanos-Domínguez

The authors are to be congratulated for a systematic investigationof the accurate and non subjective classifying approach in seismic research. The authors have conducted several clustering algorithms to the seismic event records from Volcanological and SeismologicalObservatory at Manizales. Their objective was to improve the grouping of seismic data (i.e., volcano-tectonic earthquakes, long-period earthquakes and icequakes) digitized at 100.16 Hz sampling frequency.Their study seems adding new approach to their previous work of Langer et al. (2006) who applied different classification techniques to seismic data

Design optimisation of Propeller Boss Cap Fins for enhanced propeller performance

Economic pressures and regulatory requirements have brought about a great interest in improving ship propulsion efficiency. This can be exercised by installing Energy Saving Devices (ESD) such as Propeller Boss Cap Fins (PBCF). This paper demonstrates an approach for optimising PBCF by using Computational Fluid Dynamics (CFD) analysis. The conducted Reynolds-averaged Navier-Stokes (RANS) CFD open water model tests were validated by comparison with experimental data until the simulation was deemed satisfactory within the capabilities and limitations of the model. A design and optimisation procedure was defined to analyse the impact of ESDs on propeller efficiency and then used to evaluate the influence of alternative geometric parameters and locations of the PBCF on the hub. This analysis was done at full scale using high fidelity CFD-based RANS methods. Outcomes of the study include a design and optimisation process that can be used for the analysis of other ESDs on the market. The influences of various PBCF geometry were examined with optimal solutions presented for the analysis case. Results indicated a net energy efficiency improvement of 1.3% contributing to a substantial minimisation of cost and energy consumption. A reduction in the hub vortex was also clearly identified and presented

Combining satellite data and appropriate objective functions for improved spatial pattern performance of a distributed hydrologic model

Abstract. Satellite-based earth observations offer great opportunities to improve spatial model predictions by means of spatial-pattern-oriented model evaluations. In this study, observed spatial patterns of actual evapotranspiration (AET) are utilised for spatial model calibration tailored to target the pattern performance of the model. The proposed calibration framework combines temporally aggregated observed spatial patterns with a new spatial performance metric and a flexible spatial parameterisation scheme. The mesoscale hydrologic model (mHM) is used to simulate streamflow and AET and has been selected due to its soil parameter distribution approach based on pedo-transfer functions and the build in multi-scale parameter regionalisation. In addition two new spatial parameter distribution options have been incorporated in the model in order to increase the flexibility of root fraction coefficient and potential evapotranspiration correction parameterisations, based on soil type and vegetation density. These parameterisations are utilised as they are most relevant for simulated AET patterns from the hydrologic model. Due to the fundamental challenges encountered when evaluating spatial pattern performance using standard metrics, we developed a simple but highly discriminative spatial metric, i.e. one comprised of three easily interpretable components measuring co-location, variation and distribution of the spatial data. The study shows that with flexible spatial model parameterisation used in combination with the appropriate objective functions, the simulated spatial patterns of actual evapotranspiration become substantially more similar to the satellite-based estimates. Overall 26 parameters are identified for calibration through a sequential screening approach based on a combination of streamflow and spatial pattern metrics. The robustness of the calibrations is tested using an ensemble of nine calibrations based on different seed numbers using the shuffled complex evolution optimiser. The calibration results reveal a limited trade-off between streamflow dynamics and spatial patterns illustrating the benefit of combining separate observation types and objective functions. At the same time, the simulated spatial patterns of AET significantly improved when an objective function based on observed AET patterns and a novel spatial performance metric compared to traditional streamflow-only calibration were included. Since the overall water balance is usually a crucial goal in hydrologic modelling, spatial-pattern-oriented optimisation should always be accompanied by traditional discharge measurements. In such a multi-objective framework, the current study promotes the use of a novel bias-insensitive spatial pattern metric, which exploits the key information contained in the observed patterns while allowing the water balance to be informed by discharge observations.</jats:p

Constraints and perceived freedom levels ın the leisure of university students

The purpose of this research is to examine the leisure constraints and level of perceived freedom of university students according to different variables. 250 university students in total, 174 (69%) of whom are males and 78 (31%) of whom are females selected by random sampling have voluntarily attended the research study. A survey model has been used in the study. The sample of the study consists of students studying at Istanbul University's Faculty of Sports Sciences. In order to identify the leisure obstacles of the participants, the Obstacles of Leisure Scale, which was developed by Alexandris and Carroll (1997) and adopted into Turkish by Karaküçük and Gürbüz (2007); and in order to identify the level of perceived freedom of the participants, the Perceived Freedom in Leisure Scale, which was developed by Witt and Ellis (1985) and adopted into Turkish by Yerlisu Lapa and Ağyar (2011), were used along with a personal information form prepared by the researcher as a data collection tool in the research. Percent (%) and frequency methods have been utilized to identify the distribution of the personal information of the participants and the Shapiro-Wilks normality test has been applied to identify whether data had normal distribution. Mann-Whitney U and Kruskall Wallis tests have been applied to determine the significant differences after it was determined that the data were suitable to non-parametric test conditions. According to the gender variable, no significant difference (except Individual Psychology) has been identified in the sub-dimensions of the obstacles of the leisure scale and perceived freedom in leisure scale (p&gt;0.05). While there is a significant difference in all sub-dimensions of the perceived freedom in leisure scale (p&lt;0.05), no significant difference has been found in the sub-dimensions of the obstacles of the leisure time scale (p&gt;0.05) according to age. In conclusion, it has been determined that while there are no differences between the leisure obstacles according to the gender of the participants, the level of perceived freedom increases as the age increases

University students’ opinions of the meaning of leisure and their perceived freedom in leisure

The aim of this study is to examine the perceptions of university students towards leisure and perceived freedom in leisure on the basis of different variables. To this end, a total of 250 university students in total, 174 (69%) of whom are males and 78 (31%) of whom are females selected by random sampling have voluntarily attended the research study. The sample of the study consists of students studying at Istanbul University's Faculty of Sports Sciences. The data collection instruments of the study include the personal information form developed by the researcher, as well as the Leisure Meanings Inventory which was developed by Esteve et al. (1999) and adapted into Turkish by Gürbüz et al. (2007) and aims to determine the leisure perceptions of the participants. The Perceived Freedom in Leisure Scale, which was developed by Witt and Ellis (1985) and adapted into Turkish by Yerlisu, Lapa and Ağyar (2011) was used to determine the participants’ perceived freedom levels in leisure. Additionally, frequency methods have been utilized to identify the distribution of the personal information of the participants and the Shapiro-Wilks normality test has been applied to identify whether data had normal distribution. Mann-Whitney U and Kruskall Wallis tests have been applied to determine the significant differences after it was determined that the data were suitable to non-parametric test conditions. According to the gender variable, no significant difference has been identified in the sub-dimension of the perceived freedom in leisure scale (p&gt;0.05). In the active-passive participation and goal orientation sub-dimensions in the leisure meanings inventory, the female participants were found to score more than male participants. Based on the age variable, there were no significant differences found in any sub dimension of the perceived freedom scale (p&lt;0.05) or in the leisure meanings inventory (p&gt;0.05). In conclusion, the perceived leisure levels of the female participants were higher than the male while it was also seen that as age increases, the perceived freedom levels in leisure increases as well

Sensitivity of Columbia Basin Runoff to Long-Term Changes in Multi-Model CMIP5 Precipitation Simulations

In this study, we used precipitation elasticity index of streamflow, to reflect on the sensitivity of streamflow to changes in future precipitation. We estimated precipitation elasticity of streamflow from: (1) simulated streamflow by the VIC model using observed precipitation for the current climate (1963–2003); (2) simulated streamflow by the VIC model using simulated precipitation from 10 GCM - CMIP5 dataset for the future climate (2010–2099) including two different pathways (RCP4.5 and RCP8.5) and two different downscaled products (BCSD and MACA). The hydrological model was calibrated at 1/16 latitude-longitude resolution and the simulated streamflow was routed to the subbasin outlets of interest i.e. Hungry Horse subbasin. We used hydrological model simulations from 19063-2003 and calculated streamflow sensitivities and precipitation elasticity for the same period using observed climate (case 1) and simulated climate (case 2). The runoff sensitivity to long-term (e.g., 30-year) average annual changes in precipitation is calculated based on the elasticity of streamflow for three different 30 year blocks (2010-40, 2040-70 and 2070-99), which are of importance to reservoir management in the Columbia River basin. These two cases and different periods are compared to assess the effects of forcing by different climate models and different pathways on the precipitation elasticity of streamflow