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Drought assessment, characterisation and monitoring increasingly requires considering not only precipitation but also the other meteorological parameters such as an evapotranspiration. Thus, some new drought indices based on precipitation and evapotranspiration have been developed. This study introduces a new drought index named the water surplus variability index (WSVI). The procedure to estimate the index involves accumulation water surplus at different time scales. To approve the proposed procedure, the WSVI is compared with the standardized precipitation index (SPI), the reconnaissance drought index (RDI) and the standardized precipitation evapotranspiration index (SPEI) based on 1-, 3-, 6- and 12-month timescales using data from several weather stations located in regions with different aridity index. Near perfect agreement (d ~ 1) between WSVI and SPI, RDI and SPEI was indicated in humid and sub-humid locations. The results also showed that the correlation coefficients between WSVI and SPI, RDI and SPEI were higher for semi-arid stations than for arid ones.

Summary The evaluation of spatiotemporal characteristics of drought was based on monthly precipitation data from 29 synoptic stations for the period of 1948–2012. The percent of normal precipitation was applied to illustrate the driest years in Serbia (1990, 2000, and 2011). The Standardized Precipitation Index (SPI) and S-mode principal component analysis (PCA) were used to capture the drought patterns. Agglomerative hierarchical cluster analysis was applied to identify three different drought sub-regions: (1) region R1 includes the north and the northeast part of Serbia; (2) region R2 includes the western part of Central Serbia and southwestern part of Serbia; and (3) region R3 includes central, east, south and southeast part of Serbia. The R2 had the monthly precipitation values above average, while R1 and R3 had the precipitation values under average of Serbia. The year 2000 was the driest and 1955 was the wettest during the observed period. The characteristics of drought were analyzed in terms of the temporal evolution of the SPI-12 values and the frequency of drought for the three identified regions. The percentage of years characterized by drought was 44.62% for R1, 50.77% for R2 and 46.15% for R3. Approximately 70% of the frequency of drought belongs to the near normal drought category.

Drought represents a combined heat-precipitation extreme and has become an increasingly frequent phenomenon in recent years. In order to access the entire analysis of drought, it is necessary to include the analysis of several types of drought. In this paper, impacts of meteorological and agricultural drought were analyzed across the Standardized Precipitation Index (SPI) and Agricultural Rainfall Index (ARI) on the territory of Serbia for the period from 1980 to 2010. For both types of drought, year 2000 is notable as the year when most of the observed stations had the highest drought intensity. It was found that meteorological drought for year 2000 has a higher intensity in the central and southeastern parts of the country, as well as in the north. Of all the stations, the highest intensity of meteorological drought was observed at Loznica station in 1989. Agricultural drought in 2000 had the lowest intensity in western Serbia. Key words: drought, meteorological drought, agricultural drought, Standardized Precipitation Index, Agricultural Rainfall Index, Serbia.

This paper investigates the effects of several parameters (amounts of organic matter, grain size, content of solid phase, stirring rate, and temperature) on the adsorption of stearyl dimethyl benzyl ammonium chloride (SDBAC) in natural zeolite tuff in the process of formation of adsorbents based on organo-zeolite, a potential filter in waste water treatment process. Obtained results show that the most favorable ratio between the amount of SDBAC and zeolites is 50-75 mmol M+/kg. Larger grains have lower zeolite adsorption power of organic cations on the surface of zeolite, while favorable percentage of content of solids in the zeolite suspension is 10-20%. Interference between adsorption of mixture and temperature, especially in volumes of SDBAC lower than 75 mmol M+/kg of zeolite, have no significant impact on adsorption of organic cations on the surface of the zeolite. The obtained results present an initial step for defining the optimal operating parameters for forming adsorbents based on organo-zeolite as a filter potentially utilized in waste water treatment. [Projekat Ministarstva nauke Republike Srbije, br. TR 37018 i br. TR 37003]

Daily streamflow prediction is important for flood warning, navigation, sediment control, reservoir operations and environmental protection. The current paper examines the prediction and estimation capability of a new heuristic method, optimally pruned extreme learning machine (OP-ELM) model, for daily streamflows of Fujiangqiao and Shehang stations at Fujiang River. Prediction accuracy of OP-ELM method is compared with other soft computing models, i.e. adaptive neuro-fuzzy inference system-particle swarm optimization (ANFIS-PSO), multivariate adaptive regression splines (MARS) and M5 model tree (M5Tree) using cross validation technique. Prediction results of the both stations reported that the OP-ELM and ANFIS-PSO are the best in modeling daily streamflows of upstream and downstream, respectively. For improving prediction accuracy of the OP-ELM method, various kernel types are tried and the linear, linear + sigmoid + Gaussian and linear + sigmoid provide the best results for both stations. The OP-ELM outperforms the other methods during estimation of downstream streamflow using hydro climatic data as input. The OP-ELM reduces the prediction error of ANFIS-PSO by 12% in estimation of daily streamflow. It is also found that including local data considerably improves the prediction accuracy in estimation of downstream streamflows. The overall results indicate that the OP-ELM method could be successfully used in predicting and estimating daily streamflow by using hydro climatic data as inputs.

The monthly precipitation data from 29 synoptic stations for the period 1946–2012 were analyzed using a number of different multivariate statistical analysis methods to investigate the spatial variability and temporal patterns of precipitation across Serbia. R-mode principal component analysis was used to study the spatial variability of the precipitation. Three distinct sub-regions were identified by applying the agglomerative hierarchical cluster analysis to the two component scores: C1 includes the north and the northeast part of Serbia, while C2 includes the western part of Central Serbia and southwestern part of Serbia and C3 includes central, east, south and southeast part of Serbia. The analysis of the identified sub-regions indicated that the monthly and seasonal precipitation in sub-region C2 had the values above average, while C1 and C3 had the precipitation values under average. The analysis of the linear trend of the mean annual precipitation showed an increasing trend for the stations located in Serbia and three sub-regions. From the result of this analysis, one can plan land use, water resources and agricultural production in the region.

Summary Precipitation and Standardised Precipitation Index (SPI) trends were analyzed by using linear regression, Mann–Kendall and Spearman’s Rho tests at the 5% significance level. For this purpose, meteorological data from 12 synoptic stations in Serbia over the period 1980–2010 were used. Two main drought periods were detected (1987–1994 and 2000–2003), while the extremely dry year was recorded in 2000 at all stations. The monthly analysis of precipitation series suggests that all stations had a decreasing trend in February and September, while both increasing and decreasing trends were found in other months. On the seasonal scale, there were the increasing trends in autumn and winter precipitation series, while on the annual scale the most of the stations had no significant trends. Besides, the decreasing trend was found at the Belgrade and Kragujevac stations, while the other stations had the increasing trend for the SPI-12 series.

The annual and seasonal trends of seven meteorological variables were analyzed for twelve weather stations in Serbia during 1980–2010. The non-parametric Mann-Kendall and Sen's methods were used to determine whether there was a positive or negative trend in weather data with their statistical significance. The occurrence of abrupt changes was detected using cumulative sum charts and bootstrapping. In the present study, the increasing trends were indicated in both annual and seasonal minimum and maximum air temperatures' series. The relative humidity decreased significantly in summer and autumn, while the vapor pressure had a significant increasing trend in spring, summer and autumn. Besides, no significant trends were detected in summer and winter precipitation series. In general, the results of using the Mann-Kendall and Sen's tests demonstrated the good agreement of performance in detection of the trend for meteorological variables.

The data of 12 water quality parameters have been daily monitored at the Nis station on the Nisava River during 2000-2004. The trend analysis was performed on monthly, seasonal and annual time series using the Mann-Kendall test, the Spearman’s Rho test and the linear regression at the 5% significance level. The monthly results showed that significant trends were found only in pH, total hardness, Ca and SO4 data. The results in seasonal series indicated that the significant trends were detected in pH, total hardness, Cl, Ca and SO4 data. In annual series, the trends were insignificant at the 5% significance level. [Projekat Ministarstva nauke Republike Srbije, br. TR37018]

Application of adsorbents based on organo-zeolites has certain advantages over conventional methods applied in food industry wastewater treatment process. The case study presented in this paper examines the possibilities and effects of treatment of dairy industry wastewater by using adsorbents based on organo-zeolites. The obtained results indicate favorable filtration properties of organo-zeolite, their high level of adsorption of organic matter and nitrate nitrogen in the analyzed wastewater. This paper concludes with recommendations of optimal technical and technological parameters for the application of these filters in practice.

Prediction of precipitation is one of the important factors that affect the sectors such as industry, agriculture, environmental protection, and their related fields. The stochastic method based on a Markov chain model is used in the paper to predict the annual precipitation in the territory of South Serbia for the period 2009-2013. For this purpose, the precipitation data rainfall recorded on the four synoptic stations were used for the period 1980-2010. [Projekat Ministarstva nauke Republike Srbije, br. TR 37003: Razvoj hidroinformacionog sistema za pracenje i ranu najavu susa]

The ability to optimize an artificial neural network (ANN) and adaptive neuro-fuzzy inference system (ANFIS) in reference evapotranspiration (ET0) estimation using the cuckoo search algorit...

1Faculty of Civil Engineering and Architecture, University of Nis, Aleksandra Medvedeva 14, 18000 Nis, Serbia 2Faculty of Architecture and Engineering, Canik Basari University, Gurgenyatak Koyu, Canik, 55080 Samsun, Turkey 3University of Illinois at Urbana-Champaign, 2204 Griffith Drive, Champaign, IL 61820, USA 4Department of Civil Engineering, University of Leuven, Kasteelpark Arenberg 40, P.O. Box 2448, 3001 Leuven, Belgium 5Faculty of Computer Science and Information Technology, University of Malaya, 50603 Kuala Lumpur, Malaysia

Drought is a natural hazard caused by the variability in climate, which cannot be prevented. However, its effects can be reduced through management systems incorporating drought monitoring. The main aim of this paper is the presentation of information system for monitoring drought warning based on the model with optimal set of hydro-meteorological parameters: minimal number, availability of gauge data and spatial distribution of measuring locations. Monitoring the relevant hydro-meteorological parameters and creation of suitable forecast tools within a hydro-information system for monitoring drought warning would serve as a platform for decision making in drought effects reduction. Significance of this idea is in the substitution of complex climatological models. It requires time and maintenance investments with a practical method for estimation of drought duration and intensity which will satisfy the users' needs and will not require considerable economic investment. [Projekat Ministarstva nauke Republike Srbije, br. TR 37003: Development of hydro-information system for monitoring and early drought warning]

Software used for estimating reference evapotranspiration (ET"0) has been developing in various directions. The main goal of this paper is to present an approach based on Service-Oriented Architecture (SOA) paradigm for modeling and estimating ET"0. The FAO-56 Penman-Monteith (FAO-56 PM) and Hargreaves equation are used for estimating monthly ET"0. The weather data for this study were obtained from CIMIS for Davis weather station. The FAO-56 PM and Hargreaves ET"0 values estimated using ET Web service were compared to corresponding CIMIS PM ET"0 estimates. The proposed model based on Web services implemented to the FAO-56 PM and Hargreaves equations has good performances and can be used in estimating ET"0 and has ability to complete missing weather data.

Evaluation of simple reference evapotranspiration (ETo) methods has received considerable attention in developing countries where the weather data needed to estimate ETo by the Penman–Monteith FAO 56 (PMF-56) model are often incomplete and/or not available. In this study, eight pan evaporation-based, seven temperature-based, four radiation-based and ten mass transfer-based methods were evaluated against the PMF-56 model in the humid climate of Iran, and the best and worst methods were selected from each group. In addition, two radiation-based methods for estimating ETo were derived using air temperature and solar radiation data based on the PMF-56 model as a reference. Among pan evaporation-based and temperature-based methods, the Snyder and Blaney–Criddle methods yielded the best ETo estimates. The ETo values obtained from the radiation-based equations developed here were better than those estimated by existing radiation-based methods. The Romanenko equation was the best model in estimating ETo among the mass transfer-based methods. Cross-comparison of the 31 tested methods showed that the five best methods as compared with the PMF-56 model were: the two radiation-based equations developed here, the temperature-based Blaney–Criddle and Hargreves-M4 equations and the Snyder pan evaporation-based equation.

This study investigates the utility of adaptive Radial Basis Function (RBF) networks for estimating hourly grass reference evapotranspiration (ET0) from limited weather data. Nineteen days of micrometeorological and lysimeter data collected at half-hour intervals during 1962-63 and 1966-67 in the Campbell Tract research site in Davis, California were used in this study. Ten randomly chosen days (234 patterns) were selected for the RBF networks training. Two sequentially adaptive RBF networks with different number of inputs (ANNTR and ANNTHR) and two Penman-Monteith equations with different canopy resistance values (PM42 and PM70) were tested against hourly lysimeter data from remaining nine days (200 patterns). The ANNTR requires only two parameters (air temperature and net radiation) as inputs. Air temperature, humidity, net radiation and soil heat flux were used as inputs in the ANNTHR. PM equations use air temperature, humidity, wind speed, net radiation and soil heat flux density as inputs. The results reveal that ANNTR and PM42 were generally the best in estimating hourly ET0. The ANNTHR performed less well, but the results were acceptable for estimating ET0. These results are of significant practical use because the RBF network with air temperature and net radiation as inputs could be used to estimate hourly ET0 at Davis, California.

Accurate estimation of reference evapotranspiration ( ET0 ) is essential for irrigation practice. Conversion from pan evaporation data to reference evapotranspiration is commonly practiced. The objective of this study was to evaluate the reliability of simplified pan-based approaches for estimating ET0 directly that do not require the data of relative humidity and wind speed. In this study, three pan-based (FAO-24 pan, Snyder ET0 , and Ghare ET0 ) equations were compared against lysimeter measurements of grass evapotranspiration using daily data from Policoro, Italy. Based on summary statistics, the Snyder ET0 equation ranked first with the lowest RMSE value ( 0.449 mm day−1 ) . The pan-based equations were additional tested using mean daily data collected in Novi Sad, Serbia. The Snyder ET0 equation best matched ET0 estimates by Penman-Monteith equation at Novi Sad with lowest root mean square error value of 0.288 mm day−1 . The obtained results demonstrate that simplified pan-based equations can be su...

In this paper, results of certain empirical equations for estimating the daily reference evapotranspiration for the area of southern Italy have been given. Evaluation of the daily values of evapotranspiration of Policoro was conducted by the following equations: FAO-56Penman-Monteith (FAOPM), FAO-24 Penman (FAOPn), FAO-24 Blaney-Criddle (FAOBC), FAO-24 Radiation (FAOR), FAO-24 Pan, Priestley-Tailor (PT) and Hargreaves (HARG). The results strongly support the use of the FAO-24 pan and FAO-56 Penman-Monteith equations for the calculation of daily reference evapotranspiration at the location of Policoro.

Topic of this paper is air pollution as a cause of urban stress. This problem is analyzed within a case study in Bulevar Nemanjica in Nis. For the observed location, the measurements were conducted in a period of eight months (May 2007 - June 2007) by the Health Protection Institute in Nis. Motor traffic exhaust gases which were observed were: carbon-monoxide (CO), nitro-oxide (Nox) formaldehyde (HCHO). Measurements were taken at "Bulevar" green market, b standard methodology prescribed by the boundary values code book, immision measurement method, criteria for creation of measuring points and data records. Concentration of exhaust gases of motor vehicles did not exceed permissible limits, except carbon monoxide in May, while it continued to decrease and remained within the legal limits. If the Mediana - Bulevar Nemanjica location was enriched by green surface and pedestrian zones, this would lead to the decrease of exhaust gases concentration. That would prevent endangering environment and facilitate its healthy functioning.

Numerous approaches have been developed for estimating hourly reference evapotranspiration ET0, most of which require numerous meteorological data. In many areas, the necessary data are lacking and new techniques are required. The objectives of this study are: (1) to develop artificial neural networks for estimating hourly reference evapotranspiration from limited weather data; (2) to evaluate the reliability of obtained artificial neural networks (ANNs) and Food and Agricultural Organization—56 Penman Monteith (FAO-56 PM) equation compared to the lysimeter measurements; (3) to test the performance of the FAO-56 PM equation for hourly daytime periods using rc=70 s m−1 (PM70) and using a lower rc=50 s m−1 (PM50); and (4) to evaluate the reliability of obtained ANNs compared to the FAO-56 PM equation using an hourly dataset from a variety of locations. The accuracy of two reduced-set artificial neural networks (ANNTR and ANNTHR) and two FAO-56 Penman-Monteith equations with different canopy resistance values (PM50 and PM70) was assessed using hourly lysimeter data from Davis, California. The ANNTR required only two parameters (temperature and radiation) as inputs. Temperature, humidity and (Rn−G) term were used as inputs in the ANNTHR. The ANNTR and PM50 were best at estimating hourly grass ET0. The ANNTR approach was additionally tested using hourly FAO-56 PM ET0 data from California Irrigation Management Information System (CIMIS) dataset. The overall results recommended Radial Basis Function (RBF) network for estimating hourly ET0 from limited weather data. Also, the results support the introduction of new value for canopy resistance (rc=50 s m−1) in the hourly FAO-56 PM equation.

The FAO-56 Penman-Monteith combination equation (FAO-56 PM) has been recommended by the Food and Agriculture Organization of the United Nations (FAO) as the standard equation for estimating referen...

Evapotranspiration (ET) is one of the major processes in the hydrological cycle, and its reliable estimation is essential to water resources management. Numerous equations have been developed for estimating ET, most of which are complex and require numerous items of weather data. In many areas, the necessary data are lacking, and simpler techniques are required. Evaporation pans are used throughout the world because of the simplicity of technique, low cost, and ease of application. In this study, the radial basis function (RBF) network is applied for pan evaporation to evapotranspiration conversions. The adaptive pan-based RBF network was trained using daily Policoro data from 15 May 1981 to 23 December 1983. The RBF network obtained, Christiansen, FAO-24 pan, and FAO-56 Penman–Monteith equations were verified in comparison with lysimeter measurements of grass evapotranspiration using daily Policoro data from 25 February to 18 December 1984. Based on summary statistics, the RBF network ranked first with the lowest RMSE value (0·433 mm day−1). The RBF network obtained on the basis of the daily data from Policoro, Italy and pan-based equations were further tested using mean monthly data collected in Novi Sad, Serbia, and Kimberly, Idaho, USA. The overall results favoured use of the RBF network for pan evaporation to evapotranspiration conversions. The use of the RBF network is very simple and does not require any knowledge of ANNs. Users require only code (RBF network), Epan data and corresponding Ra data. Copyright © 2009 John Wiley & Sons, Ltd.

Five reference evapotranspiration (ET0) equations are evaluated using data from seven humid locations. The equations evaluated include Hargreaves, Thornthwaite, Turc, Priestley–Taylor, and Jensen–Haise. The objective of this study is to evaluate ET0 estimated by these equations against the corresponding values estimated using the standardized FAO-56 Penman–Monteith (PM) equation. For each location, ET0 estimates by the all equations were statistically compared with FAO-56 PM ET0 estimates. The Turc equation yielded the smallest root-mean-square-difference (RMSD) values at the all locations except Novi Sad, Serbia. The final ranking of equations was based on the weighted RMSD. The Turc equation has the lowest weighted RMSD and ranking first, and other equations ranked in decreasing order are: Priestley–Taylor, Jensen–Haise, Thornthwaite, and Hargreaves. The Turc equation gives the reliable calculation at all humid locations and it has proven to be the most adjustable to the local climatic conditions. The results obtained from this study, indicate very clearly that the Turc equation is most suitable for estimating reference evapotranspiration at humid locations when weather data are insufficient to apply the FAO-56 PM equation.

The Turc equation is one of the simplest empirical equations used for estimating reference evapotranspiration (ET0) under humid conditions. However, this equation generally overestimates ET0 values at windless humid locations and underestimates ET0 at windy humid locations. The main objective of this study is to develop a new adjusted Turc equation through introduction of the wind adjustment factor. In this study, data from CLIMWAT database have been divided into two groups in order to verify the model on half of the dataset. As the mean monthly data from CLIMWAT refer to the long-term average year, the detailed Western Balkans (WB) dataset with the monthly data from real years has been used for additional verification of the wind adjustment factor. For each verification station, ET0 estimates from the original and adjusted Turc equations have been statistically compared with FAO-56 Penman–Monteith (PM) ET0 estimates. The adjusted Turc equation provides good agreement with the evapotranspiration, and produces a reliable estimation at all locations. These results support the use of the adjusted Turc equation for estimating reference evapotranspiration at European humid locations where humidity data are not available.

Forming of science and technology parks is followed by the establishment of the appropriate building infrastructure that will form the park basis, as well as accompanying infrastructure facilities in which the professional staff would live and spend their time, and thus create the environment to live and work in. The science and technology park is the term which is used to describe various attempts to encourage the development of entrepreneurship through the establishment of knowledge-based small and medium-sized enterprises. The main goal of science and technology parks is joining the economic and intellectual resources in the region in which the park is established in one unit, in order to improve and enhance the existing companies' business conditions and to concentrate knowledge in one place. For this type of organization it is necessary to choose the area where the park will be built and determine the function of the complex of buildings to ensure the work of the scientists and research workers. In this paper the general conditions, which are required so that the management of the organization that founds the park would achieve the successful results, will be shown. It will present the conditions which are concerned with the necessary human, technological and infrastructural resources for the establishment of science and technology park on one territory, appropriate examples in the world and the beginning of the process of forming the science and technology park in Nis.

Floating islands represent residue of peat which swam out on surface of water after flooding former Vlasina peat-bog. These islands are refuges of plant and animal species characteristic from peat-bog habitats. These specific habitats destroyed to a great extent with exploitation of peat for different human needs and survival of many plant and animal species endangered.

Actual vapor pressure (VP) is an important parameter that is used in many evapotranspiration equations. However, vapor pressure is difficult to measure accurately. In the humid climate, the actual vapor pressure can be derived from minimum air temperature. The objectives of this study were: first, to estimate errors that can arise if VP data are not available and have to be estimated; second, to compare the Priestley-Taylor ET0 values computed under various levels of VP data availability; and third, to evaluate the reliability of Priestley-Taylor equation as compared to the FAO-56 Penman-Monteith method. The following main conclusions can be drawn: Estimated VP values generally were in closest agreement with measured VP values. The measurements of air humidity at humid locations are not indispensable for estimating reference evapotranspiration. The Priestley-Taylor method (with measured or estimated VP) provides the very good agreement with the evapotranspiration obtained by the FAO-56 Penman-Monteith method except windless locations.

A reliable estimation of the reference evapotranspiration (ET0) is of critical importance for irrigation systems' design. The goals of this research are: firstly, comparison of the evaporation methods, and secondly, analysis whether the evaporation of a Class A pan can be used as a substitution for FAO-56 PM method. In the paper, a comparison of the evaporation methods is done on the basis of the daily data from the Griffith station, Australia. It can be concluded that the Christiansen method is in better agreement with the FAO-56 PM method than the FAO-24 pan method. One of the reasons for a better agreement is a larger number of climatic parameters used than in FAO-24 pan method. The research has demonstrated that the evaporation data can be used as a substitution for FAO-56 PM ET0.

The Food and Agriculture Organization of the United Nations (FAO) has proposed using the Penman-Monteith equation as the standard for estimating reference evapotranspiration (ET 0 ), and for evaluating other equations. The basic obstacle to using the FAO-56 Penman-Monteith equation (FAO-56 PM) widely is the required weather data which are not available in most of the stations. In such circumstances, a simple empirical Hargreaves equation (HARG) is often used. However, this equation generally overestimates ET 0 at humid locations. Therefore, HARG requires local calibration. The main objective of this study is to investigate the possibility for calibrating the equation in the Western Balkans region, South East Europe through the adjustment of Hargreaves exponent (HE). Data from Palic, Sarajevo, and Nis have been used for estimating the adjusted HE. A value of 0.424 is proposed instead of the original 0.5 as one which should be used in the adjusted Hargreaves equation (AHARG) for the Western Balkan locations. The ET 0 values estimated by AHARG were compared with FAO-56 PM estimates for eight humid locations (Varazdin, Zagreb, Bihac, Novi Sad, Negotin, Kragujevac, Nis, and Vranje). Estimates by AHARG were in close agreement with FAO-56 PM estimates at most of the locations. The SEE ranged from 0.17 mm day -1 for Varazdin to 0.24 mm day -1 for Vranje, averaging 0.21 mm day -1 . The average overestimation was about 1%. These results strongly support the use of the adjusted Hargreaves equation at humid Western Balkan locations in the case when only the temperature data are available. Further research should be undertaken for evaluating the validity of the approach presented in this paper in other regions.

The Nisava river has a great importance for the sustainable development of the city of Nis. From the Mediana spring, which is on the bank of the Nisava, the city of Nis satisfies around 30% of its water demand. The aim of this paper is to, on the basis of the analysis of several tens of parameters of water quality; determine whether the Nisava river is a limiting factor to the sustainable development of the city of Nis. For this purpose the data of Public Utility Company Naissus have been used, as it collects daily samples of the Nisava river water. The number of conducted analyses, depending on the water quality parameters, varies from 1 to 1,240. The obtained results, which have been presented in detail in the paper, indicate that a great majority of analyses, of almost all the water quality parameters, is within predicted range. At the end of the paper, certain measures have been proposed, which should contribute to the sustainable development of Nis in this field. .

The Turc method is one of the simplest and most accurate empirical equations used for ETO estimation. The objectives of this study are: first, to investigate the effect of wind speed on accuracy of Turc method; second, to develop the wind speed adjustment factors for the Turc method. The adjusted Turc method provides the quite good agreement with the evapotranspiration obtained by the FAO-56 Penman-Monteith method. It gave reliable estimation at all the locations and it has proven to be the most adjustable to the local climatic conditions. These results recommend the adjusted Turc method for estimating reference evapotranspiration.

Drought assessment requires considering not only precipitation but also the other meteorological parameters such as an evapotranspiration. This paper presents the water surplus variability index (WSVI) as an indicator of drought. The calculation procedure incorporates both precipitation and reference evapotranspiration through the estimation of water surplus at different timescales. The WSVI is compared with the standardized precipitation index (SPI) and the reconnaissance drought index (RDI) based on 1-month, 3-month, 6-month, and 12-month timescales using data from four weather stations located in humid and subhumid climate. To approve the proposed procedure, the graphical and statistical tools such as the scatter plots, the linear trend, the coefficient of determination R2, the index of agreement d, and the Pearson correlation coefficient r were applied. The WSVI was highly correlated with both the RDI and the SPI whereas r>0.9. Moreover, d is greater than 0.93 which indicates near perfect agre...

The Food and Agriculture Organization of the United Nations (FAO) has proposed using the Penman–Monteith (FAO-56 PM) method as the standard method for estimating reference evapotranspiration ( ET0 ) , and for evaluating other methods. The basic obstacle to widely using this method is the numerous required data that are not available at many weather stations. The maximum and minimum air temperatures constitute a set of minimum data necessary for the estimation of ET0 . The basic goal of the paper is to examine whether it is possible to attain the reliable estimation of ET0 only on the basis of the temperature data. This goal was reached by the evaluation of the reliability of four temperature-based approaches [radial basis function (RBF) network, Thornthwaite, Hargreaves, and reduced set Penman–Monteith methods] as compared to the FAO-56 PM method. The seven weather stations selected for this study are located in Serbia (Southeast Europe). The Thornthwaite, Hargreaves, and reduced set Penman–Monteith metho...

The adoption of the Water Framework Directive is a turning point in the development of European water resources management. For the first time in the history of Europe, a uniform strategy for environment protection and water resources management was created. According to the proclaimed policy of the European Union, the Water Framework Directive pays a careful attention to the public participation in the issues concerning the water resources development. The paper gives a short presentation of the public participation in the Water Framework Directive and complementary EU directives. The right question that becomes an issue in the countries in transition is, how much the public, including the users of waters, is willing to actively participate in the implementation of the Water Framework Directive. In an attempt to obtain the answer to this question, the Regional Center for Sustainable Development and Ecology of Nis, conducted a survey of the public opinion (users of waters) about the irrigation of the Leskovac field. The public opinion survey that was conducted in the Leskovac municipality shows that a great majority of farmers comprehends the great importance of irrigation, but a negligible part of the respondents accepts the fact that the construction of the system inevitably brings about the changes in crop structure irrigation methods and water price. The obtained answers show how much the public participation, including the users of waters, is significant for the decision making in water resources management. The first task in the application of the Water Framework Directive is informing the widest possible public with the need to rationally use and protect the water resources. When the public is better acquainted with the water resources issues, it will be capable to assist in their solution.

In recent years, artificial neural networks (ANNs) have been applied to forecasting in many areas of engineering. In this note, a sequentially adaptive radial basis function network is applied to the forecasting of reference evapotranspiration (ETo). The sequential adaptation of parameters and structure is achieved using an extended Kalman filter. The criterion for network growing is obtained from the Kalman filter’s consistency test, while the criteria for neuron/connection pruning are based on the statistical parameter significance test. The weather parameter data (air temperature, relative humidity, wind speed, and sunshine) were available at Nis, Serbia and Montenegro, from January 1977 to December 1996. The monthly reference evapotranspiration data were obtained by the Penman-Monteith method, which is proposed as the sole standard method for the computation of reference evapotranspiration. The network learned to forecast ETo,t+1 based on ETo,t-11 and ETo,t-23. The results show that ANNs can be used f...

In this paper macrodiversity reception with macrodiversity selection combining (SC) receiver and two microdiversity MRC receivers operating over shadowed multipath fading channel is studied. Received signal experiences short term fading and correlated Gamma long term fading resulting in system performance degradation. Level crossing rate (LCR) of η-μ random process and level crossing rate of signals at outputs of microdiversity MRC receivers are efficiently calculated. By using these derived formulas, level crossing rate of macrodiversity SC receiver output signal process is calculated. By using this result, average fade duration (AFD) of the proposed wireless communication system can be calculated. The influence of η-μ short term fading severity parameter, Gamma long term fading severity parameter and Gamma long term correlation coefficient on level crossing rate is analysed and studied.

Statistically significant FAO-56 Penman-Monteith (FAO-56 PM) and adjusted Hargreaves (AHARG) reference evapotranspiration (ET0) trends at monthly, seasonal and annual time scales were analysed by using linear regression, Mann-Kendall and Spearman’s Rho tests at the 1 and 5% significance levels. Meteorological data were used from 12 meteorological stations in Serbia, which has a humid climate, for the period 1980–2010. Web-based software for conducting the trend analyses was developed. All of the trends significant at the 1 and 5% significance levels were increasing. The FAO-56 PM ET0 trends were almost similar to the AHARG trends. On the seasonal time scale, for the majority of stations significant increasing trends occurred in summer, while no significant positive or negative trends were detected by the trend tests in autumn for the AHARG series. Moreover, 70% of the stations were characterized by significant increasing trends for both annual ET0 series. Editor Z.W. Kundzewicz; Associate editor S. GrimaldiCitation Gocic, M. and Trajkovic, S., 2013. Analysis of trends in reference evapotranspiration data in a humid climate. Hydrological Sciences Journal, 59 (1), 165–180.

The sustainable rural development more and more depends on the efficient usage of water resources. Most often, at least in one part of the year, the rain is not sufficient for plant growth and rain plant production significantly depends on the yearly precipitation variation. The increase and stability of the agricultural production is possible in the irrigation conditions. The most part (around 70%) of the global water resources is used for food production. Irrigation water quality indicator is used to show if the available water resources have the required quality for application in agriculture. Irrigation is characterised by the complex water-plant-soil relationship, and in that eco-system the man as the end user of the irrigated fields occupies a very important place. That explains the difficulties in producing one universal classification of irrigation water quality. The paper analyses numerous water quality classifications from the aspect of the applicability on the quantifying of this indicator. The adopted classification should possess understandable, qualified and internationally comparable indicator. Thus, local classifications (Neigebauer, Miljkovic) cannot be used for this indicator. United Nation Food and Agricultural Organization (FAO) and US Salinity Laboratory (USSL) classifications are used for the evaluation of the irrigation water quality throughout the world. FAO classification gives the complex picture of the usability of the irrigation water from the point of its influence on the soil and the plants. However, the scope of the analyses is not often suited to the needs of that classification, which makes it difficult to apply. The conclusion is that the USSL (US Salinity Laboratory) classification is best suited to this range of chemical water analyses. The evaluation of the irrigation water quality indicator in the Juzna Morava river basin, upstream from the Toplica river estuary is given in this paper. Based on the obtained results, it can be concluded that the irrigation isn?t limitation for sustainable rural development.

The International Commission for Irrigation and Drainage (ICID) and Food and Agriculture Organization of the United Nations (FAO) have proposed using the Penman-Monteith method as the standard method for estimating reference evapotranspiration (ET0), and for evaluating other methods. The FAO-56 Penman-Monteith (FAO-56 PM) method requires the numerous weather data that are not available in the most of the stations. The objectives of this study were: first, to estimate errors that can arise if some weather data are not available and have to be estimated; second, to compare the FAO-56 PM ET0 values computed under various levels of data availability; and third, to determine minimum weather data requirements for estimating ET0 without decreasing the acceptable accuracy. For this study, full weather data sets were collected from six humid weather stations from Serbia (Southeast Europe).The main conclusion is that the minimum and maximum air temperature and "local default" value of wind speed are the minimum data requirements necessary to apply the FAO-56 PM method in humid climate.

This technical note presents the application of a Radial Basis Function (RBF) network to estimate the FAO Blaney-Criddle b factor. Tabular b values are given in the United Nations Food and Agriculture Organization Irrigation and Drainage Paper Number 24. The b values obtained by the RBF network are compared to the appropriate b values produced using regression equations. The RBF network predicted b values better than the regression equations. An example is given to illustrate the simplicity and accuracy of the RBF network for b factor estimation.

Climatic parameters obtained from the meteorological measurements over a long period represent a start position for monitoring and forecasting climate changes in the future. The paper observes monthly values of climatic parameters such as minimum and maximum air temperature ( T min , T max ), precipitation, wind speed at 2 m height ( u 2 ) and actual vapor pressure ( e a ) from twelve meteorological stations in Serbia during the period 1981-2010. Parameters T min , T max and e a constantly increase in the observed period. However, precipitation and u 2 decreased during the last decade. Changes and spatial distribution of monthly precipitation, T min and T max were observed during the crop growing season (April-September) in the last decade.