Reconditioning of reinforced concrete structures of drop no. 2 for discharging water into the Suda River of the Cherepovets SRPP

Recommendations for removing defects of reinforced concrete structures of a waterworks facility are presented. __________ Translated from Gidrotekhnicheskoe Stroitel’stvo, No. 2, February 2006, pp. 9–15.     

Atlas of defects and faults of turbogenerators

Photographs and drawings of 112 defects and faults of turbogenerators are analyzed and systematized. Diagnostic parameters and features are presented. Criteria of impermissibility of a defect or a fault, causes and consequences of its appearance, methods of detection, and examples are discussed.Translated from Élektricheskie Stantsii, No. 12, December 2004, pp. 50 – 55.     

Substantiation of fatigue life of hydraulic equipment with allowance for crack-type defects and damages

Problems associated with substantiation of reserve fatigue life are examined with consideration given to defects and damages. __________ Translated from Gidrotekhnicheskoe Stroitel’stvo, No. 7, pp. 38–45, July, 2006.     

Vibration adjustment of high-power turbine sets at power plants

Examples of complex cases of vibration adjustment of high-power turbosets of type K-800-240 and K-1000-60/3000 LMZ at power plants are considered. Diagnostic features of some defects strongly affecting the vibration of bearings and rotor journals are described. __________ Translated from élektricheskie Stantsii, No. 10, October 2005, pp. 22–29.     

Stability of density stratified flow in the boundary layer

1. INTRODUCTION The influence of vertical density variations o the stability of flow past a flat horizontal wall, is in sense related to the case of centrifugal forces actin on a homogeneous fluid flowing along a curved wal When the arrangement is stable, the densit decreases upward, , whereas it becomes unstabl when the variation in density is reversed. In the cas of flow with stable density stratification, turbulen mixing in the vertical direction is impeded becaus heavier particles must…     

R/S-GM(1,1)组合模型在径流预测中的应用

基于R/S分析法能提供有效的非线性科学预测,河川径流具有灰色禀性,为了提高河流径流预报精度,提出了R/S分析与灰色理论相结合的河川径流预测方法。该方法可以克服径流灰色预测存在的数据波动较大时预测精度降低的缺陷。将该方法应用到黑河莺落峡站和正义峡站的年径流量、汛期和非汛期径流量6个序列进行径流预测验证。结果表明:两站年径流量和汛期径流量序列的预测精度都在90%左右,非汛期径流量序列在80%以上,各径流序列预测结果与Mann-Kendall趋势检验一致,预测结果可靠,为河流径流量的科学预测提供了一种新方法。     

Climate Variability Influences on Hydrological Responses of a Large Himalayan Basin

The hydrological cycle, a fundamental component of climate is likely to be altered in important ways due to climate change. In this study, the historical daily runoff has been simulated for the Chenab River basin up to Salal gauging site using a simple conceptual snowmelt model (SNOWMOD). The model has been used to study the impact of plausible hypothetical scenarios of temperature and rainfall on the melt characteristics and daily runoff of the Chenab River basin. The average value of increase in snowmelt runoff for T + 1°C, T + 2°C and T + 3°C scenarios are obtained to be 10, 28 and 43%, respectively. Whereas, the average value of increase in total streamflow runoff for T + 1°C, T + 2°C and T + 3°C are obtained to be 7, 19 and 28%, respectively. Changes in rainfall by −10 and + 10% vary the average annual snowmelt runoff over the T + 2°C scenario by −1% and + 1% only. The result shows that melt is much more sensitive to increase in temperature than to rainfall.     

平底Ⅰ型马蹄形断面临界水深的直接求解

平底Ⅰ型马蹄形断面由于其形状及其尺寸容易控制,是水利水电工程中较常采用的断面形式之一,但其临界水深是超越方程,无解析解。为此,通过对平底Ⅰ型马蹄形断面临界流方程进行数学变换,对无量纲临界水深和无量纲参数之间的关系进行研究分析,应用拟合原理得到了平底Ⅰ型马蹄形断面临界水深的近似计算公式。该公式克服了传统的试算法或查表法存在的计算繁琐、依赖图表、误差较大等缺陷。在工程的常用范围内(即临界水深与拱顶半径之比：0相似文献   

6 kV系统备用自投存在问题分析

通过从事故中发电机录波器录下的数据进行分析及长期来对6kV系统自投情况的跟踪判断，发现该6kV系统备用自动投入存在着较大的缺陷问题，并提出改造建议措施。     

Utilization of Time-Based Meteorological Droughts to Investigate Occurrence of Streamflow Droughts

Complexities of streamflow drought analyses motivate utilization of simple, alternative methods, which can provide timely information for effective water resources management. For this purpose time-based meteorological drought characteristics, identified by SPI _{3 − month} , SPI _{6 − month} and SPI _Anuual are investigated. A boxplot approach is used to exclude non-rainy months from the analysis. Streamflow drought characteristics are described by drought intensities, and are calculated by the threshold level method. The non-parametric Wilcoxon–Mann–Whitney test is used to investigate relations between streamflow drought intensities and SPI _{3 − month} , SPI _{6 − month} and SPI _Anuual . The study area is the Doroodzan Watershed and Reservoir in southwestern Iran, with four rain gauge and two hydrometric stations. According to the results, most of time-based SPI values show significant relations (at 5% level of significance) with streamflow drought intensities. However, the most significant relation is between SPI _Anuual of Jamalbeik rain gauge station (centrally located in the study area) and drought intensities of Chamriz hydrometric station (located at the reservoir inlet). Comparison of study results with available records of documented droughts, confirms applicability of the proposed procedures. The SPI _Anuual is based on one-year-ahead moving average rainfalls. Then, SPI _Anuual of Jamalbeik station can be used to investigate occurrence of streamflow drought in Chamriz hydrometric station.     

Declining phosphorus as a potential driver for the onset of Didymosphenia geminata mats in North American rivers

Didymosphenia geminata is a stalk‐forming diatom capable of creating thick benthic mats in low‐nutrient streams. There are two hypotheses to explain the rapid worldwide increase in occurrence of nuisance D. geminata mats: (a) Cells are spread among rivers and across broad ecoregions through natural and anthropogenic vectors, or (2) pre‐existing D. geminata populations are forming mats in response to changing environmental conditions within the habitat. Low phosphorus (P) concentrations are a major trigger for stalk production by D. geminata cells. Although the environmental change hypothesis is gaining support among researchers, long‐term data sets demonstrating declining P concentrations prior to reported mat formation have been essentially absent from the literature. Here, we present long‐term datasets for two case studies for which long‐term P and D. geminata data coincide: the Matapedia River in Eastern Canada and the Kootenai River below Libby Dam in Montana, United States. Both rivers had declining P levels over time. However, there was a 2‐ and 20‐year lag time, respectively, between mat development and reaching the previously proposed average 2 μg/L soluble reactive P threshold for development. Although the Matapedia River provides some support of the environmental change hypothesis, the Kootenai River data set suggests other environmental factors may play a role in mat development. The data presented do not rule out the environmental change hypothesis but do suggest there may be conditions in addition to low P that must be met for mats to form and the environmental change hypothesis can likely be refined to include more parameters to better understand and mitigate the influence of mats.     

Development and Integration of Sub-hourly Rainfall–Runoff Modeling Capability Within a Watershed Model

Increasing urbanization changes runoff patterns to be flashy and instantaneous with decreased base flow. A model with the ability to simulate sub-daily rainfall–runoff processes and continuous simulation capability is required to realistically capture the long-term flow and water quality trends in watersheds that are experiencing urbanization. Soil and Water Assessment Tool (SWAT) has been widely used in hydrologic and nonpoint sources modeling. However, its subdaily modeling capability is limited to hourly flow simulation. This paper presents the development and testing of a sub-hourly rainfall–runoff model in SWAT. SWAT algorithms for infiltration, surface runoff, flow routing, impoundments, and lagging of surface runoff have been modified to allow flow simulations with a sub-hourly time interval as small as one minute. Evapotranspiration, soil water contents, base flow, and lateral flow are estimated on a daily basis and distributed equally for each time step. The sub-hourly routines were tested on a 1.9 km² watershed (70% undeveloped) near Lost Creek in Austin Texas USA. Sensitivity analysis shows that channel flow parameters are more sensitive in sub-hourly simulations (Δt = 15 min) while base flow parameters are more important in daily simulations (Δt = 1 day). A case study shows that the sub-hourly SWAT model reasonably reproduces stream flow hydrograph under multiple storm events. Calibrated stream flow for 1 year period with 15 min simulation (R ² = 0.93) shows better performance compared to daily simulation for the same period (R ² = 0.72). A statistical analysis shows that the improvement in the model performance with sub-hourly time interval is mostly due to the improvement in predicting high flows. The sub-hourly version of SWAT is a promising tool for hydrology and non-point source pollution assessment studies, although more development on water quality modeling is still needed.     

A Two-Step Infinite α-Cuts Fuzzy Linear Programming Method in Determination of Optimal Allocation Strategies in Agricultural Irrigation Systems

A two-step infinite α-cuts fuzzy linear programming (TSIFP) method is developed in this study. The introduction of infinite α-cuts to conventional fuzzy linear programming frameworks makes it possible to generate more reliable optimal results than conventional fuzzy linear programming, where finite α-cuts were assumed to be sufficient in representing all fuzzy information of the membership functions. In contrast to the previous studies, the proposed TSIFP can be noted as the first attempt in solving FLP without any unreasonable simplification and assumption. An agricultural irrigation system is then provided for demonstrating its applicability. The results show that reasonable solutions and allocation strategies are obtained. As a typical finite α-cuts fuzzy linear programming method, fuzzy robust linear programming (FRLP) is further considered to solve the same problem; results from this method are then compared with those from TSIFP. It is indicated that, due to the constraints being relaxed in FRLP, more water beyond the system’s capacity would be over-allocated for pursuing higher system benefits, implying the unreliability of FRLP in being extended to real-world practices. Two scenario analyses under different α-level cutting means for FRLP are also investigated.     

Biological aspects of Schilbe intermedius (Ruppell, 1832) in the Nyanza Gulf of Lake Victoria,Kenya

Silver butter catfish (Schilbe intermedius) is an indigenous fish species in Lake Victoria. It has a good economic value because of the quality and freshness of its flesh, increasing its demand for consumption. It is potamodromous, with its stock in the lake declining because of overexploitation by the use of illegal fishing gears at the river mouths on their way to spawning areas. Fish samples (321) were obtained from commercial gill net (1.5–3 in.) fishers within Nyanza gulf. The fish samples were weighed (g) and measured (cm), dissected and sex determined by visual inspection of the gonads. Ovaries for mature female fish specimens were preserved for analysis of fecundity. Fecundity was determined by the gravimetric technique. The mean (±SE) length and weight for all fish were 18.2 ± 0.2 cm TL and 51.9 ± 1.9 g, respectively. The female fish (20.0 ± 0.2 cm) were significantly (F = 199.80, p < .05) larger than the males (15.9 ± 0.1 cm). Similarly, the females (68.8 ± 2.6 g) were significantly (F = 152.61, p < .05) heavier than the males (30.93 ± 1.02 g). The overall sex ratio was 1.23:1.0 (female:male). The length frequency exhibited a unimodal distribution, with the modal class between 16 and 18 cm for either sex. The regression slope (b) of the length–weight relationship was 3.2, 3.1 and 3.0 for all fish, females and males. The absolute fecundity ranged from 6,510 to 59,818 eggs, with a mean of 34,473 eggs. The length at 50% maturity was estimated to be 16.0 cm (female) and 18.0 cm (male) fish. The mean length and size at maturity of S. intermedius have declined, likely attributable to fishing effects, changes in food resources, competition and predation. Thus, the present study provided relevant biological data of S. intermedius, which is currently limited for this region.     

Adaptation to Climate Change in the Management of a Canadian Water-Resources System Exploited for Hydropower

The management adaptation potential of the Peribonka River water resource system (Quebec, Canada) is investigated in the context of the evolution of climate change. The objective of this study is to evaluate the impacts on hydropower, power plant efficiency, unproductive spills and reservoir reliability due to changes in the hydrological regimes. The climate change projections used here are from the Canadian regional climate model (CRCM) nested by the Canadian-coupled global climate model (CGCM3) forced with the SRES A2 greenhouse gas emission scenario. The hydrological regimes were simulated with the distributed hydrological model Hydrotel. They were incorporated into a dynamic and stochastic optimization model in order to adapt the operating rules of the water resource system annually, according to the evolution of the climate. The impacts were analyzed over the years 1961–2099, split into four periods for comparison purposes: control period (1961–1990), horizon 2020 (2010–2039), horizon 2050 (2040–2069) and horizon 2080 (2070–2099). The main results indicate that annual mean hydropower would decrease by 1.8% for the period 2010–2039 and then increase by 9.3% and 18.3% during the periods 2040–2069 and 2070–2099, respectively. The trend to increase is statistically significant starting from 2061 (Mann–Kendall with p = 5%). The change in the mean annual production is statistically significant for the 2040–2069 and 2070–2099 periods (t-test with p = 5%). Also, the change in the variance is significant for the periods 2010–2039, 2040–2069 and 2070–2099 (F-test). Annual mean unproductive spills would increase from 1961–2099, but the trend is not statistically significant. However, the changes in the variance of the annual mean spills are significant in the periods 2010–2039, 2040–2069 and 2070–2099. Overall, the reliability of a reservoir would decrease and the vulnerability increase as the climate changes.     

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.     

Soil Erosion Assessment in a Hilly Catchment of North Eastern India Using USLE, GIS and Remote Sensing

In the present study, soil erosion assessment of Dikrong river basin of Arunachal Pradesh (India) was carried out. The river basin was divided into 200 × 200 m grid cells. The Arc Info 7.2 GIS software and RS (ERDAS IMAGINE 8.4 image processing software) provided spatial input data and the USLE was used to predict the spatial distribution of the average annual soil loss on grid basis. The average rainfall erositivity factor (R) for Dikrong river basin was found to be 1,894.6 MJ mm ha⁻¹ h⁻¹ year⁻¹. The soil erodibility factor (K) with a magnitude of 0.055 t ha h ha⁻¹ MJ⁻¹ mm⁻¹ is the highest, with 0.039 t ha h ha⁻¹ MJ⁻¹ mm⁻¹ is the least for the watershed. The highest and lowest value of slope length factor (LS) is 53.5 and 5.39 respectively for the watershed. The highest and lowest values of crop management factor (C) were found out to be 0.004 and 1.0 respectively for the watershed. The highest and lowest value of conservation factor (P) were found to be 1 and 0.28 respectively for the watershed. The average annual soil loss of the Dikrong river basin is 51 t ha⁻¹ year⁻¹. About 25.61% of the watershed area is found out to be under slight erosion class. Areas covered by moderate, high, very high, severe and very severe erosion potential zones are 26.51%, 17.87%, 13.74%, 2.39% and 13.88% respectively. Therefore, these areas need immediate attention from soil conservation point of view.     

Bi-site Analysis of Meteorological Drought Duration: Theoretical Modeling and Application

Droughts are regional incidents that threat the environment and limit most of the socio-economic activities. Given the dry and wet state sequences for two sites, X_t^{( 1 )}X_t^{\left( 1 \right)} and X_t^{( 2 )}X_t^{\left( 2 \right)} , this paper presents a procedure to reduce the two sequences X_t^{( 1 )}X_t^{\left( 1 \right)} and X_t^{( 2 )}X_t^{\left( 2 \right)} to one sequence Z _t for the purpose of simplifying the analysis of drought duration at two sites jointly. Theoretical models to evaluate the expected value and the variance of the process Z _t and the occurrence probability of the dry state at two sites jointly are presented and verified using simulation experiments. Historical data for the period 1939–2005 and generated rainy season precipitation data for two gauging sites in Central Jordan, namely Amman Airport and Madaba, is used in the present study to investigate the occurrence of droughts. The joint analysis of drought duration obtained using the historical precipitation at the two sites appears to be inconsistent especially for droughts of duration longer than 3 years. On the other hand, the joint analysis of drought duration obtained theoretically by employing the characteristics of the process Z _t are found to match well with the more reliable drought statistics obtained empirically by analyzing the long generated precipitation. Considering 25 years planning horizon, droughts of 1, 2, and 3 years duration are the most frequent droughts in the region of Central Jordan. The return period of such regional droughts ranges from 8–30 years.     

Length–weight relationships of four indigenous fish species collected in Assam and Meghalaya,India

The length–weight relationships (LWRs) of four indigenous fish species; namely Parambassis baculis (Hamilton, 1822); Pethia gelius (Hamilton, 1822); Channa stewartii (Playfair, 1867); and Leiodon cutcutia (Hamilton, 1822) collected from the Ranganadi River in Assam, and the Simsang and Kynshi River in Meghalaya are presented in the present study. The value of the parameter b recorded for P. baculis = 3.347; P. gelius = 3.924; C. stewartii = 2.979; and L. cutcutia = 3.205, with regression coefficients (r²) of 0.993, 0.963, 0.983 and 0.955, respectively. Parameter a was 0.0124 for P. baculis, 0.0037 for P. gelius, 0.0098 for C. stewartii and 0.0273 for L. cutcutia. As information on the LWRs of these fish species is not available in the FishBase database, it should assist future researchers to better analyse the stock of these fishes.     

Flooding tolerance of Sagittaria latifolia and Sagittaria rigida under controlled laboratory conditions

Pool‐scale growing‐season water‐level reductions (drawdowns) have been implemented on the Upper Mississippi River in an effort to improve fish and wildlife habitat. Aquatic vegetation is a key habitat component, with perennial emergent species, such as Sagittaria latifolia and Sagittaria rigida, especially important. River managers have assumed the need for continuous drawdown during the growing season with limited reflooding and used this guidance in assessing the potential for an ecologically successful drawdown. However, information on the effects of growing‐season flooding episodes on survival and growth of Sagittaria is limited. To assess the flooding tolerance of S. latifolia and S. rigida, we evaluated multiple levels of timing, duration, and depth on survival and productivity of plants. Plants were produced from S. latifolia and S. rigida seeds and S. latifolia tubers; all were reared under moist‐soil or shallow‐flooded rearing conditions. Mortality of plants was low (2%) among plants from large tubers, low (7%) among seedlings (and largely associated with early flooding treatments), and modest (11%) among plants from small tubers (with no clear effects of inundation). Flooding treatments generally had a positive effect on biomass production from seedlings, particularly when treatments occurred early, were relatively shallow, and were short in duration. There were no clear effects of depth, duration, or timing components of flooding treatments on plant biomass arising from tubers. This experiment indicates that S. latifolia and S. rigida are relatively tolerant of flooding events during the growing season and may actually benefit from some level of inundation.