Comparability Analyses of the <Emphasis Type="Italic">SPI</Emphasis> and <Emphasis Type="Italic">RDI</Emphasis> Meteorological Drought Indices in Different Climatic Zones

Comparability analyses are performed to investigate similarities/differences of the standard precipitation index (SPI) and the reconnaissance drought index (RDI), respectively, utilizing precipitation and ratio of precipitation over potential evapotranspiration (ET ₀). Data are from stations with different climatic conditions in Iran. Drought characteristics of the 3-month, 6-month and annual SPI and RDI time series are developed and Markov chain order dependencies are investigated by the Log-likelihood, AIC and BIC tests. Steady state probabilities and Markov chain characteristics, i.e., expected residence time in different drought classes and time to reach “Near Normal” class are investigated. According to results, both indices exhibit an overall similar behaviour; particularly, they follow the first order Markov chain dependency. However, climatic variability may produce some differences. In several cases, the “Extremely Dry” class has received a more critical value by RDI. Furthermore, the expected residence time of “Near Normal” class and expected time to reach “Near Normal” class are quite different in a number of cases. The results show that the RDI by utilizing the ET ₀ can be very sensitive to climatic variability. This is rather important, since if the drought analyses are for agricultural applications, utilization of the RDI would seem to serve a better purpose.     

Performance Evaluation of Reference Evapotranspiration Estimation Using Climate Based Methods and Artificial Neural Networks

This study is an attempt to find best alternative method to estimate reference evapotranspiration (ET_o) for the Mahanadi reservoir project (MRP) command area located at Raipur (Chhattisgarh) in India, when input climatic parameters are insufficient to apply standard Food and Agriculture Organization (FAO) of the United Nations Penman–Monteith (P–M) method. To identify the best alternative climatic based method that yield results closest to the P–M method, performances of four climate based methods namely Blaney–Criddle, Radiation, Modified Penman and Pan evaporation were compared with the FAO-56 Penman–Monteith method. Performances were evaluated using the statistical indices. The statistical indices used in the analysis were the standard error of estimate (SEE), raw standard error of estimate (RSEE) and the model efficiency. Study was extended to identify the ability of Artificial Neural Networks (ANNs) for estimation of ET_o in comparison to climatic based methods. The networks, using varied input combinations of climatic variables have been trained using the backpropagation with variable learning rate training algorithm. ANN models were performed better than the climatic based methods in all performance indices. The analyses of results of ANN model suggest that the ET_o can be estimated from maximum and minimum temperature using ANN approach in MPR area.     

Evaluation of Class A Pan Coefficient Models for Estimation of Reference Crop Evapotranspiration in Cold Semi-Arid and Warm Arid Climates

Evapotranspiration and evaporation measurements are important parameters for many agricultural activities such as water resource management and environmental studies. There are several models which can determine pan coefficient (K _Pan), using wind speed, relative humidity and fetch length conditions. This paper analyses seven exiting pan models to estimate K _Pan values for two different climates of Iran. Monthly mean reference crop evapotranspiration (ET₀) was calculated according to the pan-ET₀ model. The results showed that estimated pan coefficients by majority of the suggested models were not statistically accurate to be used in the pan-ET₀ conversion method. However, for the cold semi-arid climate condition, the best K _Pan models for estimation of ET₀ were Orang and Raghuwanshi–Wallender, respectively. Also, the Snyder and Orang models were best fitted models for warm arid climate, respectively. The mean annual value of K _Pan, determined by Penman–Monteith FAO 56 (PMF-56) standard model for warm arid sites, was approximately 32% higher than the corresponding value in the cold semi-arid climate. Similarly, the mean annual ET₀ in the warm arid sites was 66% higher, compared to the ET₀ of the cold semi-arid sites. These types of warm arid and semi-arid climates are found widely throughout the world.     

Evaluation of Global Daily Reference ET Using Oklahoma’s Environmental Monitoring Network—MESONET

The objective of this study is to evaluate the potential utility of the USGS Global Data Assimilation System (GDAS) 1-degree, daily reference Evapotranspiration (ET₀) products by comparing them with observed Oklahoma mesonet daily ET₀ over a 2 year period (2005–2006). The comparison showed a close match between the two independent ET₀ products, with bias within a range of 10% for most of the sites and the overall bias of − 2.80%. The temporal patterns are strongly correlated, with a correlation coefficient above 0.9 for all groups. In summary, we conclude that (1) the consistent low bias shows the original GDAS ET₀ products have high potentials to be used in land surface modeling; (2) the high temporal correlations demonstrate the capability of GDAS ET₀ to represent the major atmospheric processes that control the daily variation of surface hydrology; (3) The temporal and spatial correspondences in trend between independent datasets (GDAS and MESONET) were good. The finding in Oklahoma, a different hydro-climate region from a similar regional study conducted in California by Senay et al. (J Am Water Res Assoc 44(4):969–979, 2008), reconfirms the reliability and potential of using GDAS reference ET for regional energy balance and water resources management in many parts of the world.     

Performance of Recalibrated Equations for the Estimation of Daily Reference Evapotranspiration

An accurate estimation of reference evapotranspiration (ET₀) is of paramount importance for many studies such as hydrologic water balance, irrigation system design and management, crop yield simulation, and water resources planning and management. In the present study, Blaney-Criddle, Jensen-Haise and Hargreaves (temperature based), Priestley-Taylor, Radiation and Makkink (radiation based) and, Pan Evaporation and Christiansen (pan evaporation based) methods have been evaluated and recalibrated with respect to FAO-56 Penman-Monteith method for estimating daily ET₀ in the semi-arid Tirupati, Nellore, Rajahmundry, Anakapalli and Rajendranagar sites of Andhra Pradesh, India. Recalibrated Blaney-Criddle (temperature based), Radiation (Radiation based) and Christiansen (Pan evaporation based) methods showed a satisfactory performance at the sites. Further, recalibrated Blaney- Criddle method showed relatively better performance than Radiation and Christiansen methods in the daily ET₀ estimation. Recalibrated Blaney- Criddle method may therefore be adopted at the sites selected for the present study and also at the sites with similar climatic conditions for satisfactory daily ET₀ estimation.     

Monitoring and Assessment of Surface Water Abstractions for Pasture Irrigation from Landsat Imagery: Bega–Bemboka River,NSW, Australia

Irrigation of pasture forms the greatest single use of irrigation water in Australia yet there has been little monitoring of its spatial extent and water demands across southeast Australian coastal catchments where irrigated dairy farming forms an important rural livelihood. This paper provides an analysis of spatio-temporal patterns in the extent of irrigated pasture in the Bega–Bemboka catchment on the south coast of New South Wales from Landsat imagery, and establishes quantile regression relationships between metered monthly irrigation abstraction volumes, evaporation and rainfall. Over the metering period (2000–2007), annual water usage averages 4.8 ML ha^− 1 year^− 1, with January being the month of highest demand with an annualised usage of 10.4 ML ha^− 1 year^− 1. Analysis of Landsat imagery indicates that the spatial extent of irrigated pasture across the catchment has increased from 1266 ha in 1983 to 1842 ha by 2002, together with amalgamation of smaller holdings along less reliable streams into larger parcels along the trunk stream. Quantile regressions to estimate monthly mean and maximum abstraction volumes from monthly evaporation and rainfall data indicate that abstraction volumes are more closely correlated with evaporation. When combined with Landsat analyses of the spatial extent of irrigated areas, such relationships enable estimation of catchment-scale hydrological effects of irrigation abstractions that in turn can help guide regional-scale assessments of the ecological effects and sustainability of spatially and temporally changing irrigation abstraction volumes.     

Potential Evapotranspiration Model for Muda Irrigation Project, Malaysia

Methods to estimate free-surface evaporation E _p and potential evapotranspiration ET _p using well known models, namely, Penman–Monteith model, modified Penman method, Food and Agriculture Organization Penman–Monteith (FAO-PM) method, Blaney–Criddle method, and Christiansen method, without calibrating any model calibration parameters, for monthly time series are presented. The long-term monthly averaged daily models results are calculated using recorded average historic meteorological data (1980–1997) and compared with the USBR Class-A black pan evaporation data obtained from the Muda Agricultural Development Authority, Malaysia. The comparison results of the long-term monthly averaged daily estimates of E _p using these models show that the E _p values for the Penman–Monteith model and FAO-PM method for different months are found to be compared satisfactorily with the recorded pan evaporation data. The results of the estimated E _p values for different months, the variations of relative errors in different months, the values of mean monthly differences between recorded and estimated E _p , and the comparison between the models annual E _p with the recorded annual E _p , using these models suggest that the Penman–Monteith model can be selected as the best model in E _p estimation in the Muda Irrigation Project, Malaysia. The FAO-PM method can be considered as the second best model, successively followed by the Blaney–Criddle method, modified Penman method, and Christiansen method. Thus, the results of the Penman–Monteith model can be interpreted as the validation of the E _p model and can safely be used in ET _p estimation in the Muda Irrigation Project, Malaysia.     

Identification of Trend in Reference Evapotranspiration Series with Serial Dependence in Iran

Monitoring the temporal variations of reference evapotranspiration (ET_o) and quantifying any trends offer valuable information for regional hydrology, agricultural water requirements and water resources management. This study aimed to examine the temporal trends in the Penman–Monteith ET_o in the west and southwest of Iran by using the Kendall and Spearman tests after eliminating the influence of significant lag-1 serial correlation from the ET_o time series. The magnitudes and starting years of significant ET_o trends were determined by the Mann-Kendall rank statistic and the Theil–Sen’s estimator, respectively. For the study period of 1966–2005, a significant positive lag-1 serial correlation coefficient was observed at almost all the stations. The existence of the positive serial correlation in the ET_o series increased the possibility of the Kendall and Spearman tests to reject the null hypothesis of no trend while it is true. It was found that the Kendall test was more sensitive than the Spearman test to the existence of the positive serial correlation in the ET_o series. After removing the serial correlation effect with pre-whitening method, only three significant increasing ET_o trends were obtained at Khorram-Abad, Shahrekord and Zanjan stations at the rates of 0.16, 0.06 and 0.06 mm/day per decade, respectively. The significant increasing ET_o trends of Khorram-Abad, Zanjan and Shahrekord stations started in 1997, 1994 and 1998, respectively. The stepwise regression method showed that wind speed was the most dominating variable affecting on the significant changes of ET_o.     

Increasing the efficiency of the power stations of JSC “Mosénergo”

The work of the JSC“All-Russian Institute of Thermal Technology (JSC “VTI”) on electrical power stations of the “Mosénergo” power system is described. Two vital questions have arisen in the course of this work: ensuring the functionality and reliable operation of equipment which has outlived its design lifetime and refitting the power stations to enhance their performance, reduce their environmental impact, and improve their operational characteristics in accord with the demands of the 21^st century. __________ Translated from élektricheskie Stantsii, No. 11, November 2007, pp. 73–78.     

An estimate of the errors when calculating the varying electric power losses in overhead lines due to neglecting weather conditions

An algorithm for calculating the resistance taking into account the air temperature, the working current and the wind speed is developed. A quantitative estimate is made of the effect of the load current, the conductor temperature and the wind speed on the resistance of overhead-line conductors. The ranges of the errors in calculating the annual variable electric power losses are obtained. 1 Electric Power Scientific-Research Institute (VNIIé)—subsidiary of JSC “NTTs élektroénergetiki,” Russia. Translated from élektricheskie Stantsii, No. 10, October 2008, pp. 42–49.     

Prospects for development of the Moscow and Leningradskaya Power Systems during the period to 2015

How the power systems functioned during the period from 2003 through 2005 is analyzed: an estimate of the dynamics and modes of power demand is given; development of generating capacities and modes of operation at power plants, and balances between capacity and electric power generated by the power systems is analyzed; “bottlenecks” in electrical networks are determined, and trends in prospects for the development and reconstruction of the networks are outlined. Assumptions concerning the introduction of generating capacities and formulation of predicted energy balances, and the development of system-forming networks carrying voltages of 110 kV and higher for the Moscow and Leningradskaya Power Systems are examined during the period from 2006 through 2015. Technico-economic indicators are cited for electrical-network projects planned for introduction, and also for reconstruction and technical refitting. __________ Translated from élektricheskie Stantsii, No. 5, May 2007, pp. 31–45.     

Estimation of Crop Coefficient and Evapotranspiration of Wheat (Triticum aestivum) in an Irrigation Command Using Remote Sensing and GIS

Remote sensing and Geographical Information System (GIS) techniques were used to estimate actual crop evapotranspiration of wheat crop grown in Tarafeni South Main Canal (TSMC) irrigation command of West Bengal State in India. The area under wheat crop was clipped from landuse/land cover map generated from Indian Remote Sensing Satellite P6 (IRS P6) image of January, 2004 for winter season 2003–04. The IRS P6 image and four wide field sensor (WiFS) images for different months of winter season were used to determine the Normalized Difference Vegetation Index (NDVI) and Soil Adjusted Vegetation Index (SAVI) for area under wheat crop. The relationship between vegetation indices and crop coefficients (K_c) of wheat for corresponding months were developed. Based on these developed regression equations crop coefficient maps were generated for each month of wheat crop season. Monthly reference crop evapotranspiration (ETo) was estimated based on FAO-56, Penman–Monteith method. ETo was combined with spatially distributed K_c maps of different months of wheat crop season to generate crop evapotranspiration (ET_c) maps of each month. The crop water demand of wheat estimated using spatially distributed ET_c maps for months of December 2003, January 2004, February 2004, March 2004 (1st Fortnight) and March 2004 (2nd Fortnight) were found to be 3.98, 8.14, 4.66, 2.49, and 1.21 million cubic meter (MCM) respectively. Based on crop evapotranspiration the total crop water demand of wheat crop in irrigation command of TSMC was estimated as 20.48 MCM.     

Multiple Linear Correlation Analysis of Daily Reference Evapotranspiration

An accurate estimation of reference evapotranspiration (ET₀) is of paramount importance for many studies such as hydrologic water balance, irrigation system design and management, crop yield simulation, and water resources planning and management. Simple regression techniques, may sometimes, provide adequate estimation of ET₀. Implementation of regression methods considering all the predictor variables may, however, lead to overfit and consequent reduction in the predictive capability. The regression models for ET₀ have been developed in the present study for Tirupati, Nellore, Rajahmundry, Anakapalli and Rajendranagar regions of Andhra Pradesh, India by following step-wise procedure, eliminating superfluous predictor variables based on statistical criteria. The sunshine hours, wind velocity, temperature and relative humidity influenced ET₀ in the study area. The linear regression models developed in terms of predictor variables may conveniently be applied in the regions selected for the present study and, in the regions with similar climatic conditions for satisfactory ET₀ estimation.     

Interrelation Between the Accuracy of Prediction and Irregularity of Electric Energy Demand Curves

Results of a study of the dependence of the accuracy of prediction on daily and seasonal irregularity of demand curves are described. It is shown that in power systems characterized by high irregularity of the curves errors are the highest, which lowers the competitiveness of the systems in the power market. The interrelation between the irregularity of demand curves and the accuracy of predictions can be simulated by regression equations. Prediction results are the most accurate when specially developed mathematical models allowing for meteorological factors are used. The study has been performed with the help of “Energostat” software employed by power systems of Russia. __________ Translated from Elektricheskie Stantsii, No. 5, May 2005, pp. 64 – 67.     

Substantiation of the Strength and Stability of Concrete Dams Based on the Solution of a Nonlinear Three-Dimensional Problem

An analysis of methods of nonlinear computation of concrete dams is presented, which makes it possible to determine the margin of the bearing capacity of the “structure – foundation” system. __________ Translated from Gidrotekhnicheskoe Stroitel'stvo, No. 5, May 2005, pp. 42 – 45.     

Management of Upstream Dams and Flood Protection of the Transboundary River Evros/Maritza

The flood frequency and the dikes overtopping at the downstream part of transboundary (Bulgaria–Greece–Turkey) river Evros/Maritza has increased dramatically in the last 13 years. It is not clear if the increase of flood frequency is due to climatic changes or to inappropriate management of Bulgarian dams. This fact raises the question of modeling the flood routing through the many dams in the Bulgarian territory (upstream), which receive the runoff of the 38% of the area of the Evros watershed in Bulgaria, in a way to protect the downstream countries from flooding. The basic objective of this paper is the development of a new management tool (software) for the simulation of the rainfall–runoff and routing process taking into account the existence of many dams and mainly their operation not only from a hydrologic viewpoint, but also from the administrative, with emphasis on the “energy–economic” exploitation of the reservoirs. The developed software (named Evrofloods) models the rainfall–runoff, the routing of runoff through the various Evros river tributaries taking in account various scenarios of the runoff through the artificial reservoirs with the aim of optimal management of the water released from the dams spillways and turbines. The “optimal management” is related with the finding for a given rainfall distribution, the appropriate combination of actions at many reservoirs (“reservoirs management”) in order to prevent or mitigate the floods downstream, aiming at the same time to minimize hydroelectric energy loss. Although Evrofloods software is basically dedicated to the large Evros basin, it can be easily used to determine the management of large transboundary rivers with many artificial reservoirs to avoid floods downstream. Recent European legislation on floods encourages the good cooperation of neighbor countries, to avoid floods.     

Regional Models for the Estimation of Streamflow Series in Ungauged Basins

The assessment of water resources in a region usually must cope with a general lack of data, both in time (short observed series) as well as in space (ungauged basins). Such a lack of data is generally overcome by combining rainfall–runoff models with regionalization techniques in order to transfer information to sites without or with short available observed series. The present paper aims to analyze applicability and limitations of two regionalization procedures for estimating the parameters of simple rainfall–runoff models respectively based on a “two-step” and on a “one-step” approach, for the estimation of monthly streamflow series in ungauged basins. In particular, an application to a Sicilian river basin of multiple regression equations according to a “two-step” and a “one-step” approaches and of a “one-step” approach based on neural networks is reported. For the investigated region, results indicate that models based on the “one-step” approach appear to be robust and adequate for estimating the streamflows in ungauged basins.     

Condition and control of the thermal-filtration regime of northern rock-and-earthfill dams constructed in accordance with the thaw principle

Characteristic specific features of the thermal regime of the “dam-bed” system are examined. __________ Translated from Gidrotekhnicheskoe Stroitel’stvo, No. 2, February 2008, pp. 54–58.     

应用双作物系数模型估算温室番茄耗水量

准确估算作物耗水量对于合理利用有限的水资源和制定合理的灌溉制度至关重要。本文利用3个生长季的西北地区日光温室番茄水量平衡计算耗水资料,率定和验证双作物系数模型SIMDual Kc在日光温室条件下的适用性。结果表明耗水模拟值与实测值有较好的一致性。模型估算的平均标准误差为0.55 mm·d-1,平均绝对误差为0.44 mm·d-1。模型估算的番茄初期、中期和后期的基础作物系数分别为0.50、0.85和0.55。番茄生育初期蒸发占耗水的比例最大为22.8%;发育期最小,仅为3.2%。3年全生育期总蒸发量占总耗水量的比例平均为5.9%,表明温室生产中植株蒸腾为耗水最主要部分。     

Asynchronous nonsalient-pole compensators with total air cooling1

The fundamental parameters and construction of asynchronous compensators, soon to be produced by the “Silovye Mashiny” — “élektrosila” Joint Stock Company in 2008, are considered. The compensator has a massive nonsalient-pole rotor with two excitation windings, shifted by 90° (in electrical angles), supplied from controlled reversible power sources. The compensators provide delivery-consumption of reactive power in the ±100 Mvar range with the possibility of short-term double forcing of the power output and improved dynamic characteristics compared with synchronous compensators. ¹ This paper is based on material presented at the conference “Russia Power 2008” (Moscow, April 2008). Translated from élektricheskie Stantsii, No. 11, November 2008, pp. 62–65.