Maximum Water Discharge Research Articles

Analysis of The Stability Calculation of The D.I Padang Garugur Weam In North Padang Lawas Districtnorth Sumatera

The Indonesian region is an agricultural country which causes the agricultural sector to become the main sector in supporting basic needs which is a potential value for the Padang Garurur region to become an agricultural area towards food self-sufficiency, one of the crucial issues in development at the national and global levels. The research method refers to the PU guidebook regulations. KP.06 2013, The aim of the research is to analyze and determine the stability and dimensions of the D.I Padang Garugur weir, Padang Lawas Regency against soil shear forces, overturning, landslides, earthquakes and water seepage that occur during normal and maximum water discharge. The analysis results were obtained with a design discharge of 1922.906 m3/s, a weir height of 3.36 meters, conditions when the water was normal, the overturning moment obtained fs factor 2.79 > 1.5, for soil shear it was obtained with fs 1.24 > 1.2 conditions when the water floods, the overturning moment is obtained fs = 2.09 > 1.5, it is stated that the weir is safe against overturning, the ground shear force is obtained fs 2.231 > 1.2. The conclusion states that the stability of the weir in general is greatly influenced by the physical properties or physical characteristics of the soil layers as well as the bearing capacity of the soil, as well as the control of shear, overturning, water seepage, in addition to the influence of external forces of the weir that arise during normal discharge and flood discharge conditions. it can be concluded that the D.I Padang Garugur Weir meets the stability requirements.

Hybrid Energy (Thermoelectric Generator-Archimedes Screw Turbine) Study and Experiment as a Green Energy Generator Based on the Internet of Things (IoT)

The heat energy from the hot water source of Mount Sinabung can be used as a source of electrical energy before being channeled as a source of hot water baths. The hot water flow has a fairly high temperature and a flow rate that can be converted into a source of electricity generation using a Micro Hydro Power Plant (PLTMH) and Thermoelectric Generator (TEG). This data collection was simulated using a heat source designed in a reservoir and a cold water flow that is channeled into the PLTMH-TEG system space as a source of temperature delta. This paper aims to study the TEG series TEG1-199-1.4-0.5 and the Archimedes screw Turbine (PLTMH) as a Hybrid Generator (Green Energy). Data analysis was carried out to calculate the system power output, battery charging time, and efficiency of the TEG and PLTMH. Data analysis in this study applies the Internet of Things (IoT). Test data shows that the maximum output parameter of the PLTMH during testing, obtained a maximum voltage of 20.42 Vdc. The maximum current is 759.75 mA and the maximum water discharge is 2.31 m3/s. In the TEG system, the power generated by the TEG is 20.64 watts at a temperature difference of 70.5˚C. It is concluded that the higher the amount of discharge flowing into the Archimedes turbine system and the temperature difference absorbed by the TEG, the greater the power that will be generated and vice versa.

The outburst of dammed lake Maashey (North-Chuya ridge, Central Altai)

The dammed lakes are widespread in mountainous areas and usually occur when river flow is blocked by landslides, rock glaciers, etc. Among such lakes, the most dangerous are those located in the periglacial zone and blocked by rock glaciers. Continued deglaciation of mountainous areas under changing climate conditions contributes to accumulation of large volumes of melt water in lakes, which may increase pressure on the dam, cause its failure and subsequent outburst flood. In this article we describe the development of such a lake before its outburst and the process of its outburst. The object of study was Maashei Lake (North Chuya Ridge, Central Altai) located in the zone of mountain glaciation and dammed by a rock glacier, where the lake outburst occurred in July 2012. The lake area before the outburst was 259 × 103 m2 and water volume 1.21 × 106 m3. As a result of the outburst, the lake was completely drained. We analyzed the published works on Lake Maashei, materials of our own field studies in the lake basin combined with remote sensing data. We hypothesized that the mechanism of the outburst occurred in 2012 was caused by the water erosion of the filtration channel in the dam body. The mechanism of this outburst was numerically simulated using the method presented in this article. The modeling allowed to reproduce the outburst flood hydrograph, to estimate such characteristics as maximum water discharge, volume of the outburst flood, water flow velocities and the size of the formed breach. Estimated maximum discharge was 694 m3s−1, flow velocities varied from 0.2 to 5-7 m s−1, and the outburst flood period was about 5.5 hours. The breach was formed to the full height of the dam (10 m). Its calculated morphometric characteristics were as follows: average width 47.5 m (measured 41.5 m), скоss-section area 476 m2 (measured 415 m2). The discrepancy between the modeled and measured values was about 15%.

A Robust Quantitative Method to Distinguish Runoff‐Generated Debris Flows From Floods

AbstractDebris flows and floods generated by rainfall runoff occur in rocky mountainous landscapes and burned steeplands. Flow type is commonly identified post‐event through interpretation of depositional structures, but these may be poorly preserved or misinterpreted. Prior research indicates that discharge magnitude is commonly amplified in debris flows relative to floods due to volumetric bulking and increased frictional resistance. Here, we use this flow amplification to develop a metric (Q*) to separate debris flows from floods based on the ratio of observed peak discharge to the theoretical maximum water discharge from rainfall runoff. We compile 642 observations of floods and debris flows and demonstrate that Q* distinguishes flow type to ∼92% accuracy. Q* allows for accurate identification of debris flows through simple channel cross‐section surveys rather than through qualitative interpretation of deposits, and therefore should increase the performance of models and engineered structures that require accurate flow‐type observations.

Performance evaluation of a modified axial flow water Lifting pump for small to medium irrigation in Nigeria.

Most irrigation pumps used in Nigeria are imported. Consequently, the challenges farmers faced in using these pumps include but not limited to the following; priming before operation, relatively low-capacity delivery at low head and high price which is often time not affordable by peasant farmers. The objective of this research was to develop an axial flow pump with locally sourced materials and affordable by farmers for small to medium scale irrigation in Nigeria. The design of the pump for the study was adopted from an existing and functioning axial pumping machine, developed by Agricultural Machinery and Mechatronics Department, Kasetsart University, Thailand. The pump was fabricated at the workshop of National Centre for Agricultural Mechanization (NCAM), Ilorin, Nigeria. Diesel fuel was used in powering the pump because of higher torque deliverable. The developed pump based on its capacity can be used to irrigate one hectare in one hour at 16.2 mm depth of water using 2000 rpm at 1m head and 9.6 mm depth of water using 1000 rpm at 3 m head. The maximum water discharge of 162 m3/h (45 l/s) was at 1m using a speed of 2000 rpm with water to fuel delivery of 124.29 l/s. The maximum water discharge of 162 m3/h (45 l/s) was at 1m using a speed of 2000 rpm with water to fuel delivery of 119.57m3/L. And the least water discharge of 59.30 m3/h (28 l/s) and water delivery per fuel was 41.0m3/L at 3 m head at 1000 rpm. Therefore, the developed pump operates best at lower head of 1m featuring a 3kW prime mover. The developed pump based on its capacity can be used to irrigate one hectare in one hour at 16.2 mm depth of water using 2000rpm at 1m head and 9.6 mm depth of water using 1000rpm at 3m head at a moisture content of 45% on a sand-loamy soil. Statistical analysis reveals relationships between pump speed, head, fuel consumption, and various performance indicators. The centrifugal pumps were found to produce lower discharge than axial flow pumps at different water heads evaluated. Comparative economic analysis demonstrates the pump's superiority over conventional centrifugal pumps in terms of water-fuel delivery efficiency and operational cost. This study introduced a locally modified axial flow pump as a practical, cost-effective, and efficient solution to irrigation challenges faced by small and medium-scale farmers in Nigeria. This pump has higher capacity delivery, spare parts are readily available at local market, it is appropriate for use where the irrigation head requirements are low and large volumes of water is required to be lifted at low pressure, it is appropriate where water can be lifted from rivers and canals and then directed to farmers' fields for irrigation. It is also applicable in rice farm flooding and flood drainage. This type of pump is good for flood (surface) irrigation system, which include furrow, border, basin irrigation and uncontrolled flooding in loamy and clay soils for rice production and sugarcane productions. The pump's adoption and economic viability positions it as a potential catalyst for increased food production, income, and food security in the country.

ИССЛЕДОВАНИЕ ГИДРОМЕТЕОРОЛОГИЧЕСКИХ УСЛОВИЙ ПРИ ПРОЕКТИРОВАНИИ ГИДРОТЕХНИЧЕСКИХ СООРУЖЕНИЙ НА РЕКЕ АБИН В КРАСНОДАРСКОМ КРАЕ

Purpose: to analyze the climatic characteristics of the study area and hydrological characteristics of the studied watercourse, including maximum water discharges in section lines marked along the river bed, as well as maximum water levels of the Abin River, in the volume necessary for a reasonable choice of design solutions for bank protection hydraulic structures. Materials and methods. The Abin River was studied from 1923 to 1989 at the water gage in Abinsk. Observation data allowed analyzing the regime, level and estimating the discharges. The average annual precipitation is 704 mm, with a peak in December (85 mm) and minimums in April and September (45 mm each). Heavy rains occur in the summer, with a maximum of 171 mm per day. Ice and rime phenomena occur in the area, but they are mostly short-lived. Extreme hydrometeorological phenomena are possible due to the orographic features of the region. Results. The Abin River is a mountain river with water level fluctuations of up to 8.6 m and the rising large wooden debris during floods. Calculations of maximum discharges and water levels were carried out, the average current velocity reaches 2.68–3.40 m/s, and the maximum depth is 7.54–7.64 m. Channel processes include bed erosion and limited meandering with a stable bank position. The bed erosion depth varies from 0.78 to 1.06 m. Conclusions. When developing bank protection structures on the Abin River, it is necessary to take into account several important aspects. The structures must withstand significant water discharges (at a speed of 2.68–3.40 m/s and a depth of 7.54–7.64 m BS) and ensure durability during floods. It is necessary to strengthen the foundation and reinforce the slopes using geosynthetics, and provide flexible structures (gabions and Reno mattresses) to adapt to channel changes. It is possible to use technologies that minimize interference with nature, such as anchor systems and the creation of bulkheads. It is recommended to use methods for the redistribution of sediments, including flooded spurs.

Application of CFD Simulation to Determine the Optimal Horizontal Position of the Nozzle Inlet of a Propeller Flow Cooling System (PFCS)

Research on the use of fluid flow caused by the propeller to be used for engine cooling is an interesting research topic. The system is known as the Propeller Flow Cooling System (PFCS). It is necessary to develop the most optimal position to produce maximum water discharge in this system. This research carried out simulation and analysis with an elliptical inlet nozzle as the utilization of the stern flow of the ship. This study aims to determine the difference in the volume of water generated from several horizontal positions of the nozzle inlet. In this study, the simulated horizontal distance of the inlet nozzle to the propeller at 0.7R propeller blade that is, 5 cm, 7.5 cm, 10 cm, 12.5 cm, 15 cm and using the computational dynamic fluid (CFD) method to analyze the optimal horizontal distance of the inlet nozzle which produces the highest water flow rate. Based on the research result, it was shown that the optimal horizontal distance of the inlet nozzle to the propeller is a distance of 7.5 cm. The water flow generated in the computational simulation in this case was 14.24 liters/minute. In that case, it can be concluded that the effect of the horizontal distance of the inlet nozzle on the propeller greatly affects the flow of water produced.

Modelling the historical and future evolution of six ice masses in the Tien Shan, Central Asia, using a 3D ice-flow model

Abstract. In the Tien Shan, few modelling studies exist that examine in detail how individual ice bodies are responding to climate change. Nonetheless, earlier research demonstrated that the glacier response to climate change in this mountain range is heterogeneous. Here, we use several measurements and reconstructions of the ice thickness, surface elevation, surface mass balance, and ice temperature to model in depth six different ice bodies in the Kyrgyz Tien Shan: five valley glaciers and one ice cap. The selected ice masses are located in different sub-regions of the Tien Shan with different climatic and topographic settings, and they are all characterized by detailed recent glaciological measurements. A three-dimensional higher-order thermomechanical ice-flow model is calibrated and applied to simulate the evolution of the ice masses since the end of the Little Ice Age (1850) and to make a prognosis of the future evolution up to 2100 under different Coupled Model Intercomparison Project Phase 6 (CMIP6) shared socioeconomic pathway (SSP) climate scenarios. The results reveal a strong retreat of most of the ice masses under all climate scenarios, albeit with notable variations in both timing and magnitude. These can be related to the specific climate regime of each of the ice bodies and their geometry. Under a moderate warming scenario, the ice masses characterized by a limited elevation range undergo complete disappearance, whereas the glaciers with a larger elevation range manage to preserve some ice at the highest altitudes. Additionally, our findings indicate that glaciers that primarily receive precipitation during the late spring and summer months exhibit a more rapid retreat in response to climate change, while the glaciers experiencing higher precipitation levels or more winter precipitation remain for a longer duration. Projections concerning the overall glacier runoff reveal that the maximum water discharge from the ice masses is expected to occur around or prior to the middle of the 21st century and that the magnitude of this peak is contingent upon the climate scenario, with a higher warming scenario resulting in a higher peak.

Flood hazard assessment in the Yesil River basin

Abstract Due to population growth and densification, and expanding construction, disaster risk in the world and its specific parts of the world is steadily increasing. Earthquakes cause the most damage, followed by floods. Floods are characterized by the highest frequency of events. In this research, annual data on 25 hydrological gauging stations of the considered territory were used to study the characteristics of maximum discharges and maximum levels of rivers in the Yesil water management basin. Data on maximum water levels and discharges are generalized because they are most important in the study of floods and the organization of flood control. It is the maximum level that determines the area and depth of flooding of territories. This study assessed the provided values of maximum levels and maximum water discharges by several methods (method of moments, the graph-analytical method for the full distribution, truncated distribution). For assessing flood damage, a map of the distribution of the maximum floodplain inundation depth over the basin area was constructed, taking into account the flood hazard classification by floodplain inundation layer. Quantitative assessment of hydrological extremes characterizing the danger of flooding has been carried out for gauging stations of Yesil water management basin during this research.

EVALUASI SALURAN DRAINASE AKIBAT SEDIMENTASI DENGAN MENGGUNAKAN PROGRAM HEC-RAS (CASE STUDY ON JALAN DR. SUTOMO)

EVALUATION OF DRAINAGE CHANNEL DUE TO SEDIMENTATION USING THE HEC-RAS PROGRAM (CASE STUDY ON ROAD DR. SUTOMO)Flooding is one of the natural events that can be detrimental to humans. The flood that occurs is in the form of an overflow of water and will inundate lowlands or basins. Floods can also occur as a result of rainwater being trapped in a basin that becomes a puddle or as a result of a water storage container that can no longer accommodate the amount of water that enters it. This study aims to determine: (1). To find out the results of the evaluation of drainage canals on Road Dr. Sutomo, Jepara Regency (2). To find out the results of the evaluation of drainage canals on Road Dr. Sutomo, Jepara Regency, in the existing conditions with the HEC-RAS program (3). To provide solutions to overcome flooding on Road Dr. Sutomo, Jepara Regency. The data collection method used is (1). Field survey (2) Collection of primary data and secondary data (3). Checking data completeness (4). Analyze and evaluate data using HEC-RAS Software. The results showed that the drainage capacity on Road Dr. Sutomo has a discharge of 0.52 m3/s, or the equivalent of 52 liters/s. Shows that with this future drainage condition, it cannot accommodate the incoming water discharge. Because the maximum water discharge from the HEC-RAS calculation is 11.86 m3/sec, or 11860 liters/sec.

Analysis of intake air temperature effect on performance of portable atmospheric water generation (PAWG) systems with heat sink angle orientation of 75o

The increasing demand for clean water and the diminishing supply of clean water sources can result in a clean water crisis. Air is a ubiquitous, inexpensive, and clean water source. Using Atmospheric Water Generators (AWG), the water contained in the air can be extracted. This study's objective was to determine the effect of inlet air temperature and air heater power variations on tool performance and PAWG condensate water production at a condenser angle of 75 degrees. The procedure utilized is experimental on three PAWG boxes. Each box has a distinct temperature at its entrance. The variation of inlet air temperature is accomplished by heating the air before it enters the box with an air heater; the applied power variations are 0.484 Watt, 0.964 Watt, and 1.702 Watt. The results demonstrated that variations in air heater power and inlet air temperature affected system performance and condensate water production. Maximum water discharge and PAWG performance were achieved when the air heating power was 0.48 watts and the water discharge was 1.166 milli liters per hour. At 0.0084 ml/h/W, the PSys system performance had the highest value. The variable air heating power of 0.946 Watt represents the utmost COP value of PAWG. This power variable has a high temperature difference and influences the COP value at high levels.

Application of the method of territorial long-term forecasts to determine the maximum water discharge rates under the conditions of spring flood 2022-2023 formation across the Desna basin

Despite the conditions of both climate change and long-term trend to decrease of hydrological characteristics of the Ukrainian rivers' spring flood that was established by many authors, the formation of high-water river floods accompanied by rising water levels and release of water to floodplains still remains probable.
 Thus, according to the data of the Ukrainian Hydrometeorological Center (UkrHMC) of the State Emergency Service of Ukraine (web: www.meteo.gov.ua), the hydrometeorological conditions of snowmelt and rain runoff formation during the autumn-winter and spring periods of 2022-2023 across the basins of the Dnipro and Desna rivers and their tributaries were characterized as those having a complex nature. This led to a rise of these rivers' water levels with flooding of floodplains, disruption of transport connections, as well as flooding of populated areas in Kyiv, Chernihiv and other Ukrainian regions.
 The purpose of this study is the issues related to determination of natural factors that lead to extreme large-scale spring floods, and long-term forecasting of maximum runoff of spring floods in 2022-2023 across the Desna River basin.
 To ensure operational forecasting support and assessment of the spring floods size across the basin of the Desna River and other left tributaries of the Middle Dnieper, the research used a method of territorial long-term forecasts of spring floods maximum runoff. The method takes into account a complex of hydrometeorological factors which, when combined annually, lead to the formation of spring floods of different sizes.
 The results of the long-term forecast for maximum water discharge rates during the spring flood in 2022-2023 retrieved from the forecasting computer complex "SEYM" show satisfactory statistical estimates of the forecast for maximum water discharge rates during a spring flood provided that a high pre-flood water content of the rivers during recession of a winter flood is considered. The forecast lead time for maximum water discharge rates of the spring flood in 2022-2023 varied from 20-30 days for small tributaries of the Desna River to two months for the Desna and Seim rivers themselves.
 Application of the method of territorial long-term forecasts of characteristics of river spring floods allows spatial monitoring of the rivers' water content provided that forecasting is conducted using the methodology of maximum water discharge rates for any rivers of a certain territory, including those with relation to which there are no observations of their water runoff.
 An early warning about a dangerous river water level during winter-spring periods can significantly reduce the scale of negative consequences and ensure achievement of socio-economic and environmental effects.

Water Flow Changes In The Don River (European Russia) During 1891–2019

The Don River Long near Razdorskaya Village had long phases (lasting 33–86 years) of increased/decreased naturalized annual and seasonal water flow, and their properties for 1891–2019 were identified. Long-term changes in the annual and snow-melt flood flow occurred in the opposite phase relative to changes in the winter and summer-autumn flow. Annual hydrographs in the phase of decreased flow were characterized by an increase in water discharge during the low-water seasons of the year, but a noticeable decrease in daily flood water discharge and maximum water discharge. The share of high-water years (years with a flow exceedance probability equal to or less than 25%) in the phase of increased flow is significantly higher than the share of low-water years (years with a flow exceedance probability equal to or more than 75%). And on the contrary. At the same time the cumulative share of low- and high-water years remains relatively stable. The total changes in the annual and seasonal flow, caused by both anthropogenic and climatic factors, throughout the entire period of modern global warming (since 1989) consisted in a decrease of the annual and snow-melt flood flow and an increase of flow values during low-water seasons.

კალაპოტურ პროცესებზე წყლის მაქსიმალური ხარჯის ზემოქმედების შეფასება

Mountainous relief of Georgia and climate change current trends increase the frequency of catastrophic phenomena that is manifested in particular in the fact that during intensive pouring rains takes place formation (passing) of water flows in large quantities and substantial river bed deformations. The main element of calculation of hydraulic constructions corresponding to these deformations is a value of maximum water discharge, determination of which is a complicated problem due to a question raised regarding the probability (percent provision) of this value, range of which is quite large - from 5% to 0,01%. In general, the less is the value of this probability, the more are the material expenses in the construction process (along with reliability). Different countries use different approaches when calculating maximum water discharges at the river crossings. Though, every single case has to be considered on the individual basis, the development of the common methodology, which gives us a result, close to the maximum to reality is no less important.

Modern hydrological characteristics of the Kuibyshev reservoir as a basis for the development of water bioresources

THE PURPOSE. Consider the indicators of the operation mode of the Kuibyshev reservoir over the past 15 years, affecting the state of the fish stock; identify the main trends in changes in water volumes in the reservoir due to climate change, the features of the level regime for the ecological solution of the problem of preserving aquatic biological resources.METHODS. A comparative analysis of our own research and literature data on the hydrological characteristics of the Kuibyshev reservoir, the temperature regime of the region and the state of the ichthyofauna was carried out. In this work, to analyze the current state of the hydrological regime, data provided by the Verkhniy Byef gauging station of the branch of JSC RusHydro - Zhigulevskaya HPP and the State Committee of the Republic of Tatarstan for Biological Resources were used.RESULTS. It is shown that the average water level in the Kuibyshev reservoir for the last period ranged from 50.34 to 52.31 m at NHL - 53.00 m BS, DVL - 45.5 m. Based on the totality of characteristics in terms of average water levels and inflows, 2010, 2011, 2021 can be attributed to low-water years, 2007-2009, 2012-2020 to years with average water content, and there were no high-water years during this period.The analysis of the dynamics of changes in the maximum and minimum water levels was carried out and changes were identified: the minimum recorded water level (48.16 m) was noted in January (2011), at the end of the 20th century, the minimum levels were recorded in March - April and they were lower by 1-1, 5 m in summer drawdown and 2.5 - 3.5 m in winter, the level rise occurs in April, while earlier it was in May. The duration of the high-water period (about 53 m) increased to 4 months. The minimum volume in the reservoir was recorded in the winter period of 2010-2011 - 36.14 km3, the maximum volume is 57.66 km3 in the winter period of 2019-2020. Maximum water discharges are carried out mainly in the second half of April and early May. Minimum discharges are carried out in different periods.It is shown that the number of days with an air temperature above 15°C, which characterizes the fishery zone, varies in different years of the last period from 71 days (2017) to 133 days (2020).CONCLUSION. A relative increase in temperature was noted as the most important environmental factor for the development of aquatic bioresources; currently, the process of accelerating eutrophication of shallow areas of the Kuibyshev reservoir is observed. The regular death of fish in different parts of the reservoir, combined with factors such as low water levels and high temperatures, creates the preconditions for “local catastrophes” at the level of ichthyocenoses, the area of “local catastrophes” is expanding due to climate change. The mortality of fish is a mechanism for the release of the ecosystem from excess organic matter, and the mortality of a small particle indirectly indicates a high abundance of low-value and weedy fish, the number of which must be reduced.

River Sediment Runoff in the Aldan River Basin and Mining Activities

Abstract—The article contains the results of a study of the features and causes of a sharp decrease of water turbidity and the suspended sediment discharges of rivers (1.5–5 times) in the Aldan River basin, which has been recorded since the second half of the 1980s and 1990s. The possible factors of this decrease are considered in detail. These are the runoff and temperature of water, economic activities, and the method of measurements at the gauging stations. It was found that water runoff, in general, increased in the average range of 5–30%. The maximum water discharges on the different stations had a multidirectional trends. The water temperature, as an important factor of thermal erosion, has increased. That is, hydrological factors could not have caused such a reduction in sediment runoff. Since the 1990s, the reliability of stationary data has decreased Main reason lies in the mining industry, its degradation in the 1990s, a new revival in the XXI century, but already under the pressure of strict environmental restrictions. Using numerous open sources, the author has built a map of exploited mineral deposits, identified the main stages of their development and the parameters of mining operation. All this information allowed us to substantiate the conclusion about the similarity of long-term fluctuations in river sediment runoff and the dynamics of mining, the stages of discovery and development of deposits, changes in the structure and localization, the implementation of measures to reduce the negative impact of mining on rivers. It was also found that the data of the stations from the very beginning of their collection did not reflect the natural regime of sediment discharges and water turbidity.

Assessment of runoff characteristics changes of small and medium-sized rivers in Central Yakutia under the climate change influence

The response of river catchments located on the territory of Russia to climate change in recent decades has been expressed in the emergence of multidirectional trends in the series of annual runoff, maximum water discharges and the value of winter runoff. However, the response of small and medium-sized rivers to the ongoing climate warming has been poorly studied, in contrast to large rivers. In this paper, a comprehensive analysis of the climatic and hydrological characteristics of small and medium-sized rivers of Central Yakutia as well as an assessment of the climate change impact on the river runoff characteristics in various conditions of the region were carried out. It has been established that the revealed positive trends in temperature correspond to the trends typical for the rest of the Russian Federation. The response of the runoff of small and medium-sized rivers to climate change is most significant in the winter-spring months of the year: there is an increase in runoff in the spring and winter periods and for the year as a whole. A feature of the response of the river catchments of the study area in comparison with the European part of Russia and southern Siberia is the presence of statistically significant trends in the series of annual water discharges for most of the studied water gauges. The most noticeable changes (as a percentage of the base period) occurred in the annual runoff of small rivers, because small rivers respond most quickly to external influences. Its expressiveness is determined not only by the degree of changes in climatic characteristics, but also by the features of runoff formation in the watersheds of the study area, in particular, the presence of permafrost.

Determination of the maximum flow of the river with anthropogenic factors

This study was aimed to determine the anthropogenic and natural factors affecting hydrological regime of rivers, reliability and safety of hydroelectric facilities. The work of the Uchkurgan hydroelectric complex before and after the commissioning of the Toktogul reservoir with a hydroelectric power station is considered. The observations were conducted over a period of 92 years. A significant decrease in the unevenness of the average long-term water flow has been established for various periods. A homogeneity graph was built, which showed the periods of influence of anthropogenic factors in 1975 and 1990. The following scenarios for determining the maximum water discharges were considered: local water consumption regime, commissioning of the Toktogul reservoir, and energy mode. The estimated verification flow of 0.01% security satisfies the design capacity of the hydroelectric complex of 2720 m3/s..

КЛИМАТИЧЕСКИЕ ИЗМЕНЕНИЯ ГИДРОЛОГИЧЕСКИХ ХАРАКТЕРИСТИК НА РЕКАХ РЕСПУБЛИКИ САХА (ЯКУТИЯ)

The paper deals with long-term series of different hydrological characteristics (average annual water discharges, maximum discharges throughout the year, maximum discharges during spring floods and rain floods, spring flood runoff layers, minimum summer and winter water discharges) on the rivers of the Republic of Sakha (Yakutia) and their approximation by models of the non-stationary average (the linear trend and the stepwise change model). It has been found that there are practically no effective non-stationary models for the maximum water discharges, but there are such models for flood layers and for average annual and minimum water discharges, which increased mainly in the late 20th and early 21st centuries due to the possible additional inflow of water from the thawed permafrost. The number of effective non-stationary average models increases from 30% of all cases for flood layers to 50–60% for average annual and minimum summer water discharges, and almost to 100% for minimum winter water discharges. Estimation of the stationarity of the mean values and variances by statistical criteria when dividing the series of stepwise changes by year confirmed the nonstationarity of the mean values for all a priori established nonstationary models and, in some cases, the nonstationarity of the variances. The largest increase in average values up to 100% takes place in the minimum winter water discharges, up to 70–80% – in the minimum summer water discharges, and up to 40–50% – in the average annual water discharges; a change in average values up to 20% cannot be considered statistically significant and reliably determined. Relative to natural variability, the excess is up to 1.5–1.6 standard deviation, but no more. Spatial distributions of the increase in river runoff characteristics in % relative to the previous stationary period and to natural variability are constructed. The greatest increase in the minimum winter water discharge takes place in the northern part of Yakutia. In recent years, water discharges have been observed even on freezing rivers. For the minimum summer and average annual water discharges, the largest increase occurs in the northeast and east.

What could we have learnt from the previous flood data to predict losses caused by the 1980, 1986, and 1998 catastrophic floods in Ukrainian Transcarpathian?

This paper explores some aspects relating to retrospective predicting the confirmed monetary losses caused by the disastrous floods of 1980, 1986, and 1998 in the Tisza River basin within the Transcarpathian region of Ukraine. The research was based on two time series – the losses because of past floods and the maxima water discharges gauged at the hydrological station near the village of Vylok, Vynohradiv district. The main aim of the research was to make out whether it had been the possibility to predict the losses due to those floods in advance.In solving the task, there was revealed and modelled the dependence of the risk of losses due to the floods in Transcarpathia on the maximum water discharges of the Tisza River gauged at the “Vylok” hydrological station. Predicting was based on the hypothesis of the stationary random process for maximum water discharges, which allowed using an empirical distribution function of a random variable regarding flood water discharges assessing the risk of flood losses.Retrospective predicting of the losses caused by the floods of 1980, 1986, and 1998 was carried out by means of a combined situational-inductive predictive modelling method (CSIPMM), being an original author’s development. The method relates to predicting the behaviour of complex dynamic systems based on monitoring findings presented as time series data reflecting evolutions of a resulting (dependent) variable and an explaining (independent) variable (predictor). The method uses extrapolation-regression type models. According to this method, the prediction task is performed in two stages. The first stage realises the retrospective situational modelling task aiming to obtain a set of simple regressions (situational models) built on data of sample time series. The situational models are accepted to be adequate or relevant ones only within certain periods of time determined as situations. In the second stage, based on the generalization (on an ensemble) of the obtained retrospective situational models, inductive “levels” models are built, which reflect the behaviour of a controlled parameter of the system or process (a resulting variable) at several fixed values of a predictor in time. The inductive models are used in extrapolative predicting situational models belonging to future periods (situations).In total, three predictions were made: (1) taking into account the annual maximum flood discharges from 1954 to 1979 (before the flood of 1980); (2) the same from 1954 to 1985 (before the flood of 1986); (3) the same from 1954 to 1997 (before the flood of 1998). The study found that there had been a possibility to predict the confirmed monetary losses inflicted by the flood of 1986 and 1998 (relative predicting errors of 7.2-8.7% and 6.0-12.8% depending on the prediction options).