MODERN HYDROGRAPHIC AND WATER MANAGEMENT ZONING OF UKRAINE’S TERRITORY – IMPLEMENTATION OF THE WFD-2000/60/EC

In contrast to the hydrological and hydrochemical zoning, hydrographic and water management zoning of Ukraine (2016) was created on a basin basis, taking into account the boundaries of river basins, and not physiographic zoning. The main function of hydrographic and water management zoning is water management. Primary is hydrographic zoning, and water management - based on it. The description of modern hydrographic zoning of the territory of Ukraine, approved in 2016 by the Verkhovna Rada of Ukraine and included in the Water Code of Ukraine is given. Hydrographic zoning is carried out for the development and implementation of river basin management plans. On the territory of Ukraine nine areas of river basins are allocated: Dnipro; Dnister; Danube; Southern Bug; Don; Vistula; rivers of the Crimea; rivers of the Black Sea coast; rivers of the Azov Sea coast 13 sub-basins are allocated in four river basins district. The water management zoning is described - the division of hydrographic units into water management areas, which is carried out for the development of water management balances. In the regions of the river basins in the territory of Ukraine allocated 132 water management areas, 59 of which are located in the Dnipro basin. About 9,000 bodies of surface water allocated for monitoring in Ukraine. Approved zoning is the implementation of the provisions of the EU Water Framework Directive 2000/60 / EC in the management of water resources in Ukraine. Modern hydrographic and water management zoning of the territory of Ukraine approximates the management of water resources of the state to European requirements.

DEVELOPMENT OF STREAMFLOW DROUGHT INDICES IN THE MORAVA RIVER BASIN

The territory of Czechia currently suffers from a long-lasting drought period which has been a subject of many studies, including the hydrological ones. Previous works indicated that the basin of the Morava River, a left-hand tributary of the Danube, is very prone to the occurrence of dry spells. It also applies to the development of various hydrological time series that often show decreases in the amount of available water. The purpose of this contribution is to extend the results of studies performed earlier and, using the most updated daily time series of discharge, to look at the situation of the so-called streamflow drought within the basin. 46 water-gauging stations representing the rivers of diverse catchment size were selected where no or a very weak anthropogenic influences are expected and the stability and sensitivity of profiles allow for the proper measurement of low flows. The selected series had to cover the most current period 1981-2018 but they could be much longer, which was considered beneficial for the next determination of the development direction. Various series of drought indices were derived from the original discharge series. Specifically, 7-, 15- and 30-day low flows together with deficit volumes and their durations were tested for trends using the modifications of the Mann– Kendall test that account for short-term and long-term persistence. In order to better reflect the drivers of streamflow drought, the indices were considered for summer and winter seasons separately as well. The places with the situation critical to the future water resources management were highlighted where substantial changes in river regime occur probably due to climate factors. Finally, the current drought episode that started in 2014 was put into a wider context, making use of the information obtained by the analyses.

ESTIMATION OF THE T-YEAR SPECIFIC DISCHARGE USING THE REGIONALISED SKEWNESS COEFFICIENT OF THE LOG-PEARSON TYPE III DISTRIBUTION

In this paper the results are presented of estimation of T-year specific discharge of several streams in two regions in Slovakia. The Qmax time series used in the study were observed at water gauges from lowland Slovak part of the Morava River basin, and from the mountainous Belá River basin. For estimating the design values, we have studied the use of only one type of probability distribution, namely the Log-Pearson Type III Distribution (LP3 distribution). The use of only one type of distribution brings several benefits, e.g. possibility of the regionalization of the distribution parameters (in this study skew coefficient). In the first step the design values of the specific discharge series qmax (with historical data) were estimated and regional skew coefficients Gr of the LP3 distribution were computed. Regional skewness coefficient Gr was estimated to be 0.38 in the Morava River region, and 0.73 in the Belá River region. In many cases the estimate of the 1000-year specific discharge is two times higher than the value of the 100-year specific discharge. Then we have derived the empirical relations between station skew coefficient G and the elevation of the water gauge. In the second step we have derived the empirical relationships between 1000-years specific discharge q1000 and the elevation of the water gauge for both regions separately. The derived empirical regional equations can be used to estimate the 1000-years specific discharge of other streams in the region.

ASSESSMENT OF STATISTICAL SIGNIFICANCE OF HISTORIC DANUBE FLOODS

Data on historic floods along the Danube River exist since the year 1012. In the Middle Ages, floods were estimated based on historical documents, including original handwritten notes, newspaper articles, chronicles, formal letters, books, maps and photographs. From 1500 until the beginning of organized water regime observations, floods were hydraulically reconstructed based on water marks on old buildings in cities along the Danube (Passau, Melk, Emmersdorf an der Donau, Spilz, Schonbuhen and Bratislava). The paper presents a procedure for assessing the statistical significance of registered historic floods using a comprehensive method for defining theoretical flood hydrographs at hydrological stations. The approach is based on correlation analysis of two basic flood hydrograph parameters – maximum hydrograph ordinate (peak) and flood wave volume. The PROIL model is used to define the probability of simultaneous occurrence of these parameters. It defines the exceedance probability of two random variables, in the specific case two hydrograph parameters of the form: P{Qmax more equal to qmax,p)∩(Wmax more equal to wmax,p)} = P (1) where: Qmax – maximum hydrograph ordinate (peak); qmax,p – maximum discharge of the probability of occurrence p; Wmax – maximum hydrograph volume; wmax,p – maximum flood wave volume of the probability of occurrence p; P – exceedance probability. Spatial positions of the lines of exceedance of two flood hydrograph parameters and the empirical points of the corresponding parameters of the considered historic flood in the correlation field Qmax - Wmax, allow direct assessment of the exceedance probability of a historic flood, or its statistical significance. The proposed procedure was applied in practice to assess the statistical significance of the biggest floods registered along the Danube in the sector from its mouth to the Djerdap 1 Dam. The linear trend in the time-series of maximum annual flows at a representative hydrological station and the frequency of historic floods in the considered sector of the Danube are discussed at the end of the paper.

THE MODERN MEDIUM-SCALE MAPPING OF THE AVALANCE DANGER IN THE UKRAINIAN CARPATHIANS

There is a characteristic phenomenon of mountain landscape in Avalanche. Mountain development entails the need to take into account the avalanche hazard. The important task of the Hydrometeorological Service of Ukraine is to increase the effectiveness of forecasting avalanche danger in mountainous areas of Ukraine. One of the elements on the way to its solution is the digital display of mountain areas in the form of thematic maps. The intensive development of modern GIS technologies and the availability of digital terrain models make it possible to create various thematic maps. The avalanche activity is affected by meteorological and geomorphological factors. Using DEM based on SRTM 1, an avalanche hazard map of Ukrainian Carpathians was compiled. The map is based on the average maximum snow height and the steepness of the slopes. The proposed map will improve the quality of avalanche forecasts and will allow you to determine the need for avalanche exploration if the intended area of construction falls into the avalanche zone and protect users from unnecessary danger. An algorithm for constructing thematic (avalanche) digital maps using satellite data SRTM 1 has been elaborated.

ANALYSIS OF LOW-FLOW CONDITIONS IN A HETEROGENEOUS KARST CATCHMENT AS A BASIS FOR FUTURE PLANNING OF WATER RESOURCE MANAGEMENT

Understanding and prediction of low-flow conditions are fundamental for efficient water resources planning and management as well as for identification of water-related environmental problems. This is problematic especially in view of water use in economic sectors (e.g., tourism) where water-use peaks usually coincide with low-flow conditions in the summer time. In our study, we evaluated various low-flow characteristics at 11 water stations in the non-homogenous Ljubljanica river catchment in Slovenia. Approximately 90% of the catchment is covered by karst with a diverse subsurface, consisting of numerous karst caves. The streams in the remaining part of the catchment have mainly torrential characteristics. Based on daily discharge data we calculated and analyzed values of 5 low-flow indices. In addition, by analyzing hydrograph recession curves, recession constants were determined to assess the catchment’s responsiveness to the absence of precipitation. By using various calculation criteria, we analyzed the influence of individual criteria on the values of low-flow recession constants. Recession curves are widely used in different fields of hydrology, for example in hydrological models, baseflow studies, for low-flow forecasting, and in assessing groundwater storages which are crucial in view of assessing water availability for planning water resources management. Moreover, in the study we also investigated the possible impact of projected climate change (scenario RCP4.5) on low-flow conditions in two sub-catchments of the Ljubljanica river catchment. For the evaluation we used the lumped conceptual hydrological model implemented in the R package airGR. For periods 2011-2040, 2041-2070, and 2071-2100 low-flow conditions were evaluated based on flow duration curves compared with the 1981-2010 period. The lowest discharges at all water stations in the Ljubljanica river catchment occur mostly during the summer months. Our results for the future show that we can expect a decrease of the lowest low-flows in the first two 30-year periods, while in the last one low-flows could increase by approx. 15%. However, the uncertainty/variability of the results is very high and as such should be taken into account when interpreting and using the results. This study demonstrates that evaluation of several low-flow characteristics is needed for a comprehensive and holistic overview of low-flow dynamics. In non-homogeneous catchments with a high karstic influence, the hydrogeological conditions of rivers should also be taken into account in order to adequately interpret the results of low-flow analyses. This proved to be important even in case of neighboring water stations.

TIME SERIES ANALYSIS AND FORECAST ESTIMATES FOR THE MEAN ANNUAL RIVERINE WATER RUNOFF WITHIN THE UKRAINIAN PART OF THE PRUT AND SIRET BASINS

The systematization, generalization, estimation of the variability of time series of the mean annual water runoff of rivers in of the Prut and Siret basins has been carried out, and its cyclic structure has been revealed. For this purpose, a database of average annual discharges water with 12 of hydrological observing stations on the rivers in of the Prut and Siret basins from the beginning of observations to 2015 have been created. Number of years under observation by the annual runoff values for river Prut near city of Chernivtsi is 121. Their representativeness and homogeneity for practical calculations has been evaluated. To identify and formalize the cyclic structure of time series of the mean annual water runoff of rivers in of the Prut and Siret basins used the methods of mathematical statistics and theory of random functions: a function of mathematical expected value; a function of dispersion values or standard deviation; probability distribution function; autocorrelation function. Also have been involved different of the standard mathematical criteria (criteria homogeneity, criteria of the series and of the longest series), integral curves of the differences. As a result, the structure of cyclic oscillations is revealed of the mean annual water runoff of rivers in the Prut and Siret basins and that is what made it possible to provide forecast estimates until 2050.

APPLICATION OF THE «CLIMATE-RUNOFF» MODEL TO THE ASSESSMENT OF THE DANUBE RIVER BASIN WATER RESOURCES IN THE XXI CENTURY ACCORDING TO THE CLIMATE SCENARIOS (A1B)

The results of calculations of possible state of water resources within The Danube River in the XXI century were shown. This estimation was based on the model «climate-runoff», developed in Odessa State Environmental University. As the input to model data of climate scenario A1B (model REMO) were used. Average long-term annual flow values using meteorological data (air temperature and precipitation) from the scenario for different climatic periods of XXI century were calculated. 32 points (grid nodes) which were uniformly distributed over the catchment area of The Danube River were studied. Projection of changes in water resources was given by comparing the calculation results in the past (before 1989) and in the future (1990-2030, 2031-2070, 2071-2100). The major trends in climatic factors of the flow formation and water resources were established. It is shown that the climatic conditions in the XXI century on the Danube River catchment is unfavorable for the formation of runoff. The positive component of the water balance (precipitation) remains unchanged and the negative component (evaporation) increases. Isolines of norms of climatic annual flow within the whole basin were constructed. It is established that by 2030 a significant reduction of water resources will not occur; during the 2031-2070 diminution will be 17,9%; during the 2071-2100 – 22,0%. Thus, in the XXI century, changes in the water resources of the Danube will not be destructive and irreversible.

FUZZY LOGIC BASED FLASH FLOOD FORECAST

The flash flood forecasting remains one of the most difficult tasks in the operative hydrology worldwide. The torrential rainfalls bring high uncertainty included in both forecasted and measured part of the input rainfall data. The hydrological models must be capable to deal with such amount of uncertainty. The artificial intelligence methods work on the principles of adaptability and could represent a proper solution. The application of different methods, approaches, hydrological models and usage of various input data is necessary. The tool for real-time evaluation of the flash flood occurrence was assembled on the bases of the fuzzy logic. The model covers whole area of the Czech Republic and the nearest surroundings. The domain is divided into 3245 small catchments of the average size of 30 km2. Real flood episodes were used for the calibration and future flood events can be used for recalibration (principle of adaptability). The model consists of two fuzzy inference systems (FIS). The catchment predisposition for the flash flood occurrence is evaluated by the first FIS. The geomorphological characteristics and long-term meteorological statistics serve as the inputs. The second FIS evaluates real-time data. The inputs are: The predisposition for flash flood occurrence (gained from the first FIS), the rainfall intensity, the rainfall duration and the antecedent precipitation index. The meteorological radar measurement and the precipitation nowcasting serve as the precipitation data source. Various precipitation nowcasting methods are considered. The risk of the flash flood occurrence is evaluated for each small catchment every 5 or 10 minutes (the time step depends on the precipitation nowcasting method). The Fuzzy Flash Flood model is implemented in the Czech Hydrometeorological Institute (CHMI) – Brno Regional Office. The results are available for all forecasters at CHMI via web application for testing. The huge uncertainty inherent in the flash flood forecasting causes that fuzzy model outputs based on different nowcasting methods could vary significantly. The storms development is very dynamic and hydrological forecast could change a lot of every 5 minutes. That is why the fuzzy model estimates are intended to be used by experts only. The Fuzzy Flash Flood model is an alternative tool for the flash flood forecasting. It can provide the first hints of danger of flash flood occurrence within the whole territory of the Czech Republic. Its main advantage is very fast calculation and possibility of variant approach using various precipitation nowcasting inputs. However, the system produces large number of false alarms, therefore the long-term testing in operation is necessary and the warning releasing rules must be set.

WATER RESOURCES OF THE LOWER DANUBE RIVER AND THEIR USE WITHIN THE TERRITORY OF UKRAINE

The main hydrological characteristic of the Lower Danube River namely its water runoff and sediment yield are presented. Based on SRTM data the area of the river basin within the territory of Ukraine was determined. It is equal to 6454 km2. The basin areas of the largest rivers, flowing into the lakes of the Lower Danube River, were determined too. The features of their hydrochemical regime were studied as well. Based on the remote sensing data it was specified the water area of four largest lakes in this territory namely Kahul, Yalpuh-Kuhurluy, Katlabukh and Kytai. This area at normal water level is as follows: Kahul – 90.6, YalpuhKugurluy – 235, Katlabukh – 60.7, Kytai – 52.9 km2. Using the regular monitoring and remote sensing data, it was studied the water temperature and the ecological state of the lakes. It was evaluated the spatial and temporal features of algal bloom as well. The highest algal bloom is usually observed in August in sunny and warm weather. It was presented the data about the water management and water use on the researched territory. The largest water intake is from the Danube River, much less water intake is from the local lakes. The most of water is used for irrigation needs.