Annual Water Discharge Research Articles

Unravelling Climate and Anthropogenic Forcings on the Evolution of Surface Water Resources in Southern France

In the Mediterranean, climate change and human pressures are expected to significantly impact the availability of surface water resources. In order to quantify these impacts during the last 60 years (1959–2018), we examined the hydro-climatic and land use change evolution in six coastal river basins of the Gulf of Lion in southern France. By combining observed water discharge, gridded climate, mapped land use and agricultural censuses data, we propose a statistical regression model which successfully reproduces the variability of annual water discharge in all basins. Our results clearly demonstrate that, despite important anthropogenic water withdrawals for irrigation, climate change is the major driver for the detected reduction of water discharge. The model can explain 78–88% of the variability of annual water discharge in the study catchments. It requires only two climatic indices that are solely computed from monthly temperature (T) and precipitation (P) data, thus allowing the estimation of the respective contributions of both parameters in the detected changes. According to our results, the study region experienced on average a warming trend of 1.6 °C during the last 60 years which alone was responsible for a reduction of almost 25% of surface water resources.

მდინარის ჩამონადენის განსაზღვრა ჰიდროლოგიური მონაცემების დეფიციტის პირობებში მდ. მტკვრის ჰესების კასკადის მაგალითზე

The article discusses a method for determining water discharge at intake points under the conditions of lack of hydrological data. As an example is given the calculation of the river flow at intake points of the hydroelectric power chain cascade on the river Mtkvari (Chitakhevi HPP, ZAHPP, Ortachala HPP). The data taken from the hydrological stations of ,,Likani,, and „Tbilisi“ are multiplied by the adaptation coefficient, which is obtained by dividing catchment areas of Chitakhevi HPP ZAHPP and Ortachala HPP. The method allows to receive continuous average monthly and annual water discharge at the intake points of Chitakhevi HPP, ZAHPP, Ortachala HPP, instead of incomplete hydrological data. Additionally, the impact of Zhinvali reservoir is taken into account in the calculation of river flow at intake points of the ZAHPP and Ortachala HPP. Also its effect on natural water inflow of river Mtkvari is established. The calculation results show that since of the operation of Zhinvali HPP the average annual water inflow of the river Mtkvari is decreased by 10% at the intake points of the ZAHPP and Ortachala HPP. Using the calculation results it is possible to determine the river flow for existing and planned HPPs on the section of Chitakhevi-Ortachala. The method also helps to determine the design parameters of these HPPs more accurately that is important for effective and safe operation of HPPs on the river Mtkvari during different levels of water flow.

Impact of global climate change on the surface runoff of the Chatkal River

Charvak reservoir is the largest reservoir in Uzbekistan. It is surrounded by the Tien Shan Mountains. The Chatkal River begins from the western part of The Tien Shan Mountains and flows into the Charvak reservoir. The average annual water discharge is 108 m3/s and is the largest right tributary of The Chirchik River. Based on long-term observational data, intraannual flow distribution was calculated. And trends were determined, tests for homogeneity were carried out, differential-integral curves in the observation series were evaluated. Average flow rates the error does not exceed 10%, for the coefficient of variation; the error does not exceed 15%. 4. Analysis of the difference integral curve showed since the 90s of the last century to the present time, a high water period has been observed on The Chatkal River and its tributaries. This is mainly due to the increase in annual precipitation. There is no significant change in long-term annual precipitation. However, shift happening with the type of precipitation. Namely, in the last two decades more rainy days than cold snowy days were observed.

Water Balance of a Boreal Black Schist Heap Leach Operation

The current study presents the effect of process chemistry as well as climate conditions on the water balance of a heap leach operation for black-schist ore. The research is based on the actual water balance at the Terrafame (former Talvivaara) mine site in Finland during the years 2017 and 2018 (base case). In addition, scenarios with a deviation in climatic conditions (Antofagasta case), chemistry (non-heat generation case) and effects of climate change (RCP4.5 (representative concentration pathway) case and RCP8.5 case) were investigated. In the first case, the annual precipitation and evaporation were simulated for a highly arid climate such as in the Antofagasta Mountains, whereas in the second case, an assumption was made of no excess heat generation (exothermic reactions) in the heap reactions. The base case predicted a requirement of 9,000,000 m3 annual discharge of water from the site with the heaviest annual rainfall. The discharge requirement and therefore the water footprint of the plant was shown to be highly dependent on the climatic conditions, as the Antofagasta case predicted a discharge of water from the site as low as zero. Heat generation, typical of the reactions dominating in a boreal black-schist heap leach operation, was shown to be vital for water management operations and therefore discharge management in Nordic climatic conditions (the non-heat generation case), where the discharge requirement was shown to be nearly threefold compared to the base case (2018). If the black-schist ore body resided in Antofagasta, the freshwater consumption would be over eight times the current consumption in the base case in Finland. Climate change scenarios show that the changing climate would increase the range of variation but only increase the need for water discharge from the site by 5% in the wettest years, while raw water utilization would increase by 46 to 83% during the driest years. In general, the results highlight the issues related to the mass and energy balance of a heap leach nickel process, and therefore feasibility—showing that although the heat generation is ore- and process-specific, the water consumption as well as discharge to the surrounding environment is highly dependent on the climatic conditions (precipitation, temperature) in the geographical location.

Реконструкция стока реки Обь по данным метеорологических наблюдений.

The connection of the Ob river flow variability with meteorological parameters in different parts of its catchment area is considered. Areas of the prevailing influence of the air temperature and different types of precipitation on Ob runoff fluctuations were identified. The long-term series of average annual water discharge in the Salekhard hydrometric station for the period 1936–2015 is reconstructed. The reconstructed series reproduces the measured interannual fluctuations and long-term trends of the average annual water discharge and found it to be good.

Пространственное распределение структурно-гидрографических характеристик речных систем бассейна озера Байкал

Analysis of structural and hydrographic characteristics of the structure of river systems and their interconnections was carried out for the future use in calculating runoff and the conditions of its formation for unexplored rivers. An annual normal and maximum water discharge observed in the 96 gauging sections of the standard observation network are hydrological basis. The research of river systems was carried out on the basis of topographic maps of scales of 1: 500 000 and 1: 200 000 and radar topographic surveys, which became the basis for constructing static and dynamic models of river systems. The static model is a totality of permanent watercourses and reflects the conditions of continuous flow. The system of impermanent and episodic watercourses is filled in the period of extreme flow. Аt this time, earlier element of the channel network without inflow become elements of a higher order. This model is dynamic. The study was conducted for the river systems of the Russian part of the Baikal basin. All parameters of river systems and their basins are divided into simple, structural and expositional classes, characterizing the conditions for the formation of thalwegs and runoff. The seven areas are identified which combine river systems when studying complex of the calculated parameters. The average structural module is a criterion for the distribution of the study territory into homogeneous area for the calculation of water discharge. The average structural module is determined by the local relation of annual normal water discharge on the total entropy of river systems. This relationship allows runoff calculations for watercourses that are not provided with hydrological information. In connection with this, a new stage of studies of the relationships between the characteristics of the structural class of the water-erosion network and the parameters of the river basin as an indicator of maximum aquifer ability arises.

РОЗРАХУНКОВІ ХАРАКТЕРИСТИКИ СЕРЕДНЬОГО РІЧНОГО СТОКУ ВОДИ ПРАВОБЕРЕЖНОЇ ТА ЛІВОБЕРЕЖНОЇ ЧАСТИН БАСЕЙНУ Р. ДНІСТЕР ДО М. ЗАЛІЩИКИ

The Dniester River is the second longest and most watery river in Ukraine, which is characterized by heterogeneity and diversity of conditions for the formation of water flow, both in terms of its length and numerous tributaries. The right-bank and left-bank parts of the Dniester River basin are quite different in terms of physical and geographical conditions, drainage network density, water regime and river water content. The object of the study is the average annual water flow of the rivers of the Dniester River basin, the subject is its calculated characteristics of different probabilities of exceeding. The purpose of the study is to analyze, systematize, generalize and compare the calculated characteristics of the average annual water flow of rivers of the right-bank and left-bank parts of the Dniester basin. Input data is based on the average annual river water discharge from 50 stream flow measuring stations in the Dniester River basin (to Zalishchyky). The data bank was formed from the beginning of observations until 2016. 89% of 28 right-bank stream flow measuring stations have a continuous series of more than 50 years, and 86% of 22 left-bank stream flow measuring stations have a continuous series of observations of more than 50 years. As for the catchment areas of rivers in the closing areas, the right bank is dominated by small ones – 64% of 28 stations have an area of less than 500 km2 and 25% – from 500 to 1,000 km2. 37% of 22 stations on the left bank have a catchment area of less than 500 km2 and 41% – from 500 to 1,000 km2. According to statistical criteria, the series of observations of the average annual river water discharge in both parts were mainly homogeneous and representative. Analytical distribution curves were calculated by the method of moments, as the coefficients of variation do not exceed 0.50. Generalization and comparison of the calculated characteristics of the average annual water flow of different probabilities of exceeding the rivers of the right-bank and left-bank parts of the Dniester basin have shown that the smallest scatter of certain analytical ordinates is observed for the probability of exceeding 50%, the transition coefficients from the norm are close to 1. The greatest spread of variation of ordinates is observed at extreme probabilities of excess of distributions, that is 0,01 % and 99 %. Analysis of the ranges of variability of transition coefficients from the norm of average annual water consumption has shown that the intensity of their change in the region of rare probabilities (0.01, 0.1, 1 %%) on the left bank is more significant than on the right bank of the Dniester basin. As for low-water supplies (95, 97, 99 %%), their ranges of variability coincide in both studied parts.

Spatial distribution of specific runoff in Serbia based on rainfall-runoff relationship

One of the indicators of water potential and water resources is specific runoff. Specific runoff for the whole territory of Serbia was obtained using the exponential relation between depth of runoff Y (mm) and precipitation P (mm). This relation is obtained on the basis of the mean annual amount of precipitation and annual water discharge, namely the depth of the runoff for 69 basins for the period 1961-2010. Coefficient of determination (R?) of relation between the depth of runoff and precipitation is 0.72. The differences between measured and modeled values of specific runoff vary from basin to basin, but at the level of the whole Serbia it is 3.5%. More precisely, the measured specific runoff amounts 5.6 l/s/km2, and the modeled specific runoff is 5.7 l/s/km2. The verification was done by applying the model to 11 large river basins in Serbia. Spatial distribution of the modeled specific runoff is presented by a digital map of specific runoff with pixel resolution 100 ? 100 m which enables the estimation of mean annual water discharge in any ungauged basin in Serbia.

БАГАТОРІЧНА МІНЛИВІСТЬ СТАТИСТИЧНИХ ПАРАМЕТРІВ РОЗПОДІЛУ СЕРЕДНЬОГО РІЧНОГО СТОКУ ВОДИ РІЧОК УКРАЇНИ З НАЙДОВШИМИ РЯДАМИ СПОСТЕРЕЖЕНЬ

The purpose of the study is to study and analyze the long-term variability of the statistical parameters of the distribution of the average annual water flow (norms, variation coefficients, and asymmetry) of the rivers of Ukraine, which have long series of observations. For this, we used the sequence of observations of the average annual water discharge at hydrological posts: river Dniester – the city of Zalishchyky, an observation period of the year 1882-2015; river Prut – the city of Chernivtsi, 1895-2015; river Desna – the city of Chernihiv 1895-2015; river Pripyat -the city of Mozyr, 1882-2014; river Southern Bug – the city of Alexandrovka, 1914-2015; river Danube – the city of Reni, 1861-2015; river Dnipro – the village of Lotsmanskaya Kamenka, 1818-2015. The duration of actual continuous observations varies from 102 to 155 years. The longest series of average annual water discharges was 198 years (the Dnieper River – the village of Lotsmanskaya Kamenka), but it consists of observations (1818-1961 – 144 years) and restored (1962-2015 – 54 years). To identify the long-term variability of the main parameters of the distribution of the average annual water flow, a comparison method is used. In our case, we compared the main statistical parameters of the rivers understudy for individual 30-year periods – sequential and with an overlap of 15 years – with the main parameters that were determined for the entire observation period. The determination of the average absolute deviations of the main statistical parameters for 30-year periods from the parameters for a long-term period, defined in %, made it possible to analyze the degree of their long-term variability. Slight variation in time has runoff norms and variation coefficients, which can be considered the most stable distribution parameters. In a long-term section, the variability of these parameters for runoff norms is in the range from 2 % to 14 %, for variation coefficients – from 7 % to 23 %. It should be noted that the highest percent deviations (14 % and 23 %, respectively) are for the observed average annual flow of water on the river Prut – the city of Chernivtsi, which turned out to be heterogeneous according to the Fisher criterion. The greatest amplitude of time variability falls on asymmetry coefficients, for which the average absolute deviation of parameters over 30-year periods from parameters over a long-term period for the studied rivers is in the range from 29 % to 98 %.

Корреляционные связи многолетних колебаний месячного и годового стока в бассейне реки Урал

This article examines the strength of perennial fluctuations’ relationship in monthly and annual runoffs in the Ural River basin. The norms of monthly and annual runoffs were calculated for the rivers of this basin. Using the wavelet analysis method, trends of their changes and water flow cycles were identified. An estimation of the river flow spatial correlation within the studied river basin was made. On the basis of a periodically correlated process model, the time series was predicted for the selected hydrological seasons. The relationship strength between the monthly average discharge of each month and the average annual water discharge, as well as between the average monthly water discharges were estimated. The statistical significance of the identified correlations was determined. A significantly stronger correlation between the values of the runoff within the year in comparison to that of the interannual was established. The last finding may be due to the long-period oscillation presence in the temporal series that helps manifest the rhythm of the annual and intra-annual cycles. It is proposed to consider the runoff fluctuations in the Ural River basin as a random stochastic process consisting of two components: inertial (trend) and seasonal (oscillating).

Temporal variation of water discharges in the lower course of the Danube River across the area from Reni to Izmail under the influence of natural and anthropogenic factors

The Danube River mouth is a main source for fresh water used for water supply and irrigation purposes in the arid southern part of Ukraine. In addition, the water of the mouth is used for filling the Danube Lakes. Climate change and numerous social and economic factors reduce the area and the water level of the Danube Lakes and increase their salinity. Under these circumstances the water exchange between the Danube River and the lakes is a very important process which allows maintenance of the water–salt balance of the latter. Such water exchange massively depends on the Danube River regime. The paper presents research of temporal variation of typical water discharges in the lower course of the Danube River associated with assessment of natural and anthropogenic factors affecting river runoff fluctuations. Time series of annual average water discharge at the water gauging stations of such cities as Reni and Izmail were considered uniform for the selected periods. They cover the period of conventionally natural river runoff regime (1840–1920), the period of the least altered river runoff regime (1921–1960) and the most altered river runoff regime under a heavy anthropogenic influence (1961–1989). The analysis of the impact of climate changes on the river runoff allowed introduction of a new, modern period of the Danube River hydrological regime (1990–2015). It is established that the series of maximum and minimum water discharges are characterized by the lack of their uniformity from the beginning of the period of initial influence of hydraulic engineering structures on the hydrological regime (since 1961). The analysis of the aggregate multi-year series (1840–2015) of average annual, maximum and minimum water discharges of the Danube River across its length from Reni to Izmail showed the presence of positive trends. At the same time the period of climatic changes (after 1989) is characterized by a less intensive growth of maximum water discharges. The research resulted in establishing the periodicity and synchronism of water discharge fluctuations in the lower course of the Danube River from Reni to Izmail within the territory of Ukraine. In particular, the study showed for the first time that from the 2000s onwards the redistribution of river runoff between the Danube River branches led to unsynchronization of minimum river runoff in different parts of the Danube Delta. The research shows that comprehensive analysis of the Danube River hydrological regime under modern climatic conditions is required to ensure efficient engineering regulation of the Danube Lakes filling pattern. Such regulation, in its turn, will ensure that the water supply and irrigation purposes are achieved.

Spatio Temporal Variation in Streamflow and Sediment Discharge in Middle Godavari Basin During 1969-2016

The present study focuses to investigate the trend in the annual water and sediment discharge for Middle Godavari Basin. Daily data of stream flow and suspended sediment concentration is collected from 19 hydrometric stations. The trend was determined by applying Mann-Kendall and Sen’s slope estimator. The analysis of stream flow revealed that out of 19 stations, 17 stations reported decreasing trend and analysis of sediment discharge revealed that all 19 stations reported decreasing trend. Pettit test is carried out to identify the abrupt change in water discharge and sediment discharge. The present case study would be useful to the policy maker’s for effective management of water resources in the area.

Precipitation and Temperature Oscillation and its Effects on the Flow of Indus Water System and Adaptation in the Arid Region, Pakistan (1940-2000)

The study evaluates the water discharge of the Indus and its sub-rivers in the arid region of Pakistan from1940-2004 using the annual changes in addition to seasonal flux and inconsistencies in culmination of the water flow.Currently, in Pakistan, the gross per capita water availability shows notable dwindle during 1951 till 2000. Owing todecline in precipitation (0.6inch or 15.2mm) and amplify in degree of hotness of 1.60C for the period of 1960-2000, thewater discharge throughout Pakistan particularly in the arid region reveals a susceptible stipulation from 1940-2004.During Rabi season, the decline in the water discharge of the Indus River and its tributaries show a drasticdecline/reduction, while it remains stable in Kharif season and could do with adaptation instantly. The annual waterdischarge indicates a positive deviation in the Kabul River, while it is negative in Indus, Jhelum, Chenab, and Ravirivers. Most of the rivers in Baluchistan are altered into seasonal torrents and the water scarcity for agriculture sectorand domestic use will be at climax in the future. The decrease in the water discharge of the Indus drainage system willinfluence the crop pattern and its production in the rain fed as well as canals fed arid areas in the lower Punjab andSindh province. The specific adaptations to cope with the problem are, improvement in the irrigation system, edifice ofnew water dams and reservoirs, construction of water course guards, innovation in sanitation and sewerage system,public awareness, policy and implementation, establishment of research and development fund, crop choices, glacierretreat and planning for water resources.

Precipitation and Temperature Oscillation and its Effects on the Flow of Indus Water System and Adaptation in the Arid Region, Pakistan (1940-2000)

The study evaluates the water discharge of the Indus and its sub-rivers in the arid region of Pakistan from1940-2004 using the annual changes in addition to seasonal flux and inconsistencies in culmination of the water flow.Currently, in Pakistan, the gross per capita water availability shows notable dwindle during 1951 till 2000. Owing todecline in precipitation (0.6inch or 15.2mm) and amplify in degree of hotness of 1.60C for the period of 1960-2000, thewater discharge throughout Pakistan particularly in the arid region reveals a susceptible stipulation from 1940-2004.During Rabi season, the decline in the water discharge of the Indus River and its tributaries show a drasticdecline/reduction, while it remains stable in Kharif season and could do with adaptation instantly. The annual waterdischarge indicates a positive deviation in the Kabul River, while it is negative in Indus, Jhelum, Chenab, and Ravirivers. Most of the rivers in Baluchistan are altered into seasonal torrents and the water scarcity for agriculture sectorand domestic use will be at climax in the future. The decrease in the water discharge of the Indus drainage system willinfluence the crop pattern and its production in the rain fed as well as canals fed arid areas in the lower Punjab andSindh province. The specific adaptations to cope with the problem are, improvement in the irrigation system, edifice ofnew water dams and reservoirs, construction of water course guards, innovation in sanitation and sewerage system,public awareness, policy and implementation, establishment of research and development fund, crop choices, glacierretreat and planning for water resources.

Tightening ecological management facilitates green development in the Qilian Mountains

The Qilian Mountains Scientific Expedition was launched under the framework of the Second Tibetan Plateau Scientific Expedition Program after tightening eco-environmental management in the Qilian Mountains. The expedition focused on three key areas: (1) Ecosystem diversity and security, (2) dynamic changes in glaciers and permafrost, and (3) changes in human activities and their corresponding eco-livelihood impacts. In this scientific expedition, a comprehensive investigation was conducted according to an integrated space–drone–ground-based field survey and a socioeconomic survey. More than 200 researchers participated in this expedition that lasted for 260 d and spanned 47500 km. First, investigations were performed for changes in human activities before and after tightening eco-environmental management in the Qilian Mountains. The local eco-environmental benefits and economic losses after the tightening eco-environmental management were analyzed by adopting the Integrated Valuation of Ecosystem Services and Tradeoffs model and the System of Integrated Environmental and Economic Accounting method. Additionally, the telecoupling values of the overall ecosystem services of the Qilian Mountains were estimated using an innovative method. Second, investigations were performed for several glaciers located in the Qilian Mountains to evaluate the characteristics of glacier distribution and variations in glacier changes. The glacier ice storage and annual degradation rate were further estimated using data derived from a glacier inventory and Landsat images. Moreover, the characteristics of permafrost distribution in the Qilian Mountains were comprehensively analyzed. Furthermore, an innovative method was developed to estimate ground ice storage and the annual water discharge rate from permafrost in the six river basins of the Qilian Mountains. Lastly, investigations were performed on changes in the forest line in a coupled forest and shrub ecosystem using a drone and field surveys. Further, the spatial and temporal grassland patterns and the associated productivity were analyzed. Moreover, dynamic changes in the five main lakes in the Qilian Mountains were assessed at different spatial and temporal scales, and the activities of the key rare species such as the snow leopard were monitored regularly using infrared cameras. The key findings of the Qilian Mountains Scientific Expedition were as follows: (1) The ecological service functions of the Qilian Mountains are promoted by tightening eco-environmental management; (2) the ecosystem of the Qilian Mountains is recovering under a warm and wet climate, and the population of rare species is expanding; however, localized overgrazing is causing grassland degradation in some areas; (3) the glacier loss rate is accelerating, and the contribution of glacial melt to river runoff is expected to exceed the critical point; (4) over the past 10 years, the meltwater from permafrost has been as high as 1.18 km3/a, which is equivalent to 10% of the annual runoff into the Qilian Mountain rivers; (5) the value of the overall ecosystem services in the Qilian Mountains has been estimated to be as high as 1067.6 (±160.1) billion Yuan, which is much higher than the regional economic loss observed in 2017. It is suggested that the government should markedly increase ecological compensation to achieve a win-win situation for green development regarding ecological livelihood in the Qilian Mountains. The findings from this scientific expedition provide comprehensive datasets and decision-making support for the establishment and management of the Qilian Mountain National Park and the protection of the ecosystems of the Qilian Mountains. Such expeditions can provide scientific support for watershed management in states or regions located along the Silk Road Economic Belt.

Investigating Fold-River Interactions for Major Rivers Using a Scheme of Remotely Sensed Characteristics of River and Fold Geomorphology

There are frequently interactions between active folds and major rivers (mean annual water discharges > 70 m3s−1). The major river may incise across the fold, to produce a water gap across the fold, or a bevelling (or lateral planation) of the top of the fold. Alternatively, the major river may be defeated to produce a diversion of the river around the fold, with wind gaps forming across the fold in some cases, or ponding of the river behind the fold. Why a river incises or diverts is often unclear, though influential characteristics and processes have been identified. A new scheme for investigating fold-river interactions has been devised, involving a short description of the major river, climate, and structural geology, and 13 characteristics of river and fold geomorphology: (1) Channel width at location of fold axis, w, (2) Channel-belt width at location of fold axis, cbw, (3) Floodplain width at location of fold axis, fpw, (4) Channel sinuosity, Sc, (5) Braiding index, BI, (6) General river course direction, RCD, (7) Distance from fold core to location of river crossing, C-RC, (8) Distance from fold core to river basin margin, C-BM, (9) Width of geological structure at location of river crossing, Wgs, (10) Estimate of erosion resistance of surface sediments/rocks and deeper sediments/rocks in fold, ERs, ERd, (11) Channel water surface slope at location of fold axis, s, (12) Average channel migration rate, Rm, (13) Estimate of fold total uplift rate, TUR. The first 10 geomorphological characteristics should be readily determinable for almost all major rivers using widely available satellite imagery and fine scale geological maps. This use of remote sensing allows a large number of major rivers to be investigated relatively easily, including those in remote or inaccessible areas, without recourse to expensive fieldwork. The last three geomorphological characteristics should be determinable for most major rivers where other data sources are available. This study demonstrates the methodology of this scheme, using the example of the major rivers Karun and Dez interacting with active folds in the foreland basin tectonic setting of lowland south-west Iran. For the rivers Karun and Dez (mean annual water discharges 575 m3s−1 and 230 m3s−1, respectively), it was found that geomorphological characteristics Nos. 2, 3 and 7 had statistically significant differences (p-value ≤ 0.05) between the categories of river incision across a fold and river diversion around a fold. This scheme should be used to investigate a variety of major rivers from across the globe. By comparing the same parameters for different major rivers, a better understanding of fold-river interactions will be achieved.

Bedload transport in the Vistula River mouth derived from dune migration rates, southern Baltic Sea

Summary In this paper, bedload sediment transport to the Baltic Sea in the main Vistula River mouth (Przekop Wisly) is estimated. For the first time in this area, investigations were performed based on the non-invasive measurement techniques with the using of hydroacoustic tools. Repeated bathymetric surveys were carried out using a multibeam echosounder for the period with hydrological conditions close to that of the long-term mean annual water discharge. Quantification of the bedload transport, as a main factor for the subaqueous Vistula delta development, involved applying the bedform tracking technique, and estimating the dune celerity by analysing the cross-correlation functions of bed elevation profiles (BEPs). The BEPs were obtained along two transects of 500 m in length situated in two different morphological parts of the river mouth – in the “shallow” and in the “deep” sites located upstream and downstream of the submerged sandbar, respectively. Contrarily to previous observations, the bedload transport was found to take place constantly. Moreover, a significant difference in a character of dune migration between the two sites of the investigated area was determined. The “shallow” dunes migrate 7 times faster (0.022 m/h) than the “deep” ones (0.003 m/h). Estimation of the daily bedload transport towards the Baltic Sea revealed values about 40.9 t/day and 8.4 t/day for “shallow” and “deep” sites, respectively. This result can probably indicate that a significant portion of sediments (ca. 80%) transported by the river during average hydrological conditions is deposited temporarily on the submerged sandbar, causing its growth.

Generalization of the average annual water runoff of the rivers according to the hydrographic zoning of Ukraine

Aim of the research is to estimate average annual water runoff of rivers of Ukraine within river basins and sub-basins respectively to the Hydrographic zoning of Ukraine. The territory of Ukraine is divided into hydrographic units - nine areas of river basins and nine sub-basins. Methods of the research - methods of mathematical statistics and statistical analysis of the relations between hydrological variables. Scientific novelty of the research is to process the base of mean annual water discharge of rivers of Ukraine from 294 hydrometric posts from the beginning of observations until 2015 inclusive. 83 % of the posts have observation periods ≥ 50 years, and only 17 % have ≤ 50 years. Also, for the first time, the generalization of the mean annual water runoff in the rivers was carried out according to the scheme of Hydrographic zoning of Ukraine. Рractical value is determined by further development of studies of the average annual runoff of the rivers in Ukraine and its generalization according to modern observation data. Research results. Analysis of the relative values of the mean standard deviation in the calculations of the mean annual runoff of the rivers of Ukraine has shown that the series of its observations are considered representative. Dependences of the average annual discharges of water in the rivers from the area of their catchments for river basins and sub-basins proved to be of rather high approximation. Correlations is from 0,76 to 0,99, which gives grounds for using them in practical calculations within the studied river basins and sub-basins. Analysis of the spatial changes of the specific discharge of rivers in the territory of Ukraine showed that their largest values are (34-39 l · s - 1 · km - 2) fixed on small mountain catchments of the Carpathian and Crimea. In plains they vary from 12,6 l · s - 1 · km - 2 in the river basin of the Vistula River to 0,1-0,2 l · s - 1 · km - 2 in the rivers basin of the Black Sea. The general tendency is their decrease from the northwest to the southeast and south. The variation coefficients of the the mean annual runoff for rivers in the flat part of Ukraine are within the range of 0,23÷0,65, for the mountain basins 0,20÷0,45. Coefficients of asymmetry have a low positive value for the entire territory of Ukraine. The generalized ratio between coefficients of asymmetry and variation is 2÷2,5.

Land cover effect on water discharge, matter losses and surface temperature: Results of 20 years monitoring in the Šumava Mts

Three small catchments (each c. 2 km2) with different land cover (drained pasture, wetland and spruce forest) located in the Šumava Mountains in the Czech Republic (altitude 780–1026 m) were monitored continuously for 20 years. The aim of the study was to evaluate the aging of different types of land cover landscape in terms of soil acidification (loss of alkalines). Average annual water discharge from the pasture catchment was c. 60 % of annual precipitation, but 38 % and 34 % of annual precipitation from the wetland and the forest, respectively. The relatively highest water runoff was from the pasture in all months. Daily runoffs during periods of heavy rain were 26 mm from the pasture, 16 mm from the wetland and 7 mm from the forested catchment. Water discharged from the drained pasture had two times higher electrical conductivity than water from the wetland and forest due to higher concentrations of bicarbonate, nitrate, calcium, magnesium, sodium and potassium. In the wetland and forest catchments, the amounts of nitrate, sulphate, chloride, TC, TN, TP and ammonium in the precipitated water were higher than that of the discharged with water (soluble matter losses). The amount of soluble matter discharged from the pasture catchment (matter losses) was in all cases higher than the amount in the precipitated water. On sunny days in the vegetation season, the pasture catchment had higher surface temperature than the wetland and forest catchments, which had higher evapotranspiration. Thermal pictures from satellites (e.g. Landsat) or taken by airborne thermal cameras can be used for identification of landscape areas of higher water outflow and higher matter losses.

Quantifying sediment storage on the floodplains outside levees along the lower Yellow River during the years 1580–1849

AbstractThe lower Yellow River channel was maintained by artificial levees between 1580 and 1849. During this period, 280 levee breaches occurred. To estimate sediment storage on the floodplains outside the levees, a regression model with a decadal time step was developed to calculate the outflow ratio for the years when levee breaching occurred. Uncertainty analysis was used to identify the likely outflow ratio. Key variables of the model include annual water discharge, a proxy for levee conditions, and potential bankfull discharge of the channel before flood season. Uncertainty analysis reveals an outflow ratio of 0.35–0.56. We estimate that during this period, 18.8–30.1% of the total ~312 Gt of sediment load was deposited on the floodplains outside the levees. Human‐accelerated erosion in the Loess Plateau caused a 4‐fold increase in sediment delivery to the lower Yellow River, which could not be accommodated by channel morphodynamic changes. As a result, 21.2–27.5% of the total sediment load was deposited within the levees, creating a super‐elevated channel bed that facilitated an uncommonly high breach outflow ratio. Hence, the factor of a large super‐elevation relative to the mean main channel depth should be considered when designing diversions to restore floodplains. © 2018 John Wiley & Sons, Ltd.