<abstract xmlns="http://www.w3.org/1999/xhtml">

Dam construction is one of the most popular solutions for managing water resources. In recent years, changes in patterns of regional seismicity associated with large impoundment dams have raised concerns among environmentalists. In this study, five large dams located in Iran were studied from this perspective. The Gutenberg-Richter, linear regression and T-test were used to examine the seismic changes in the radius of 100 km of each of the dams during a twenty-five-year period before and after the construction of the dams. The results revealed that the seismicity level and relative density of large and small earthquakes in three of these dams have increased after dam construction. A significant difference between the magnitude of earthquakes, as well as the number of earthquakes before and after the construction of dams in the region, was recognized. However, the results of the T-test statistical analysis indicated that the mean depth of the earthquakes and their distance from the dams before and after construction have not changed significantly. Overall, these results indicated that the construction of large impoundment dams has been associated with some changes in patterns of regional seismicity. The findings would guide researchers to further investigate the type of impacts that dam construction may have on seismicity patterns.
</abstract>

Analyzing the Impact of Large Dams on Seismicity Patterns around Their Locations

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In this paper, flow through a free triangular orifice is considered. The comparison of two formulas was conducted for discharge calculations: a large orifice formula and a small orifice formula. The results show that, above a certain value of upstream head to orifice height ratio there is no need for small-large formula discrimination. The differences in the outcomes for the two formulas are negligible for upstream head to orifice height ratios greater than 3. This means that a small orifice formula can be used instead of a large orifice formula. Calculations were performed for different variants of triangle orientation (with tip downwards, sidewards and upwards) as well as for different dimensions of orifice (equilateral and isosceles). The calculations also included different submergence levels of the upper edge of the orifice and variable dimensions of the orifice with constant upstream head. Neither of these conditions affect the relative deviation values for small and large orifice formulas.
</abstract>

Discharge of a Triangular Orifice under Free Flow Conditions

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The paper focuses on research on improving the water supply of drainage systems of humid areas in the context of climate change. The aim of the research is to elaborate on the ways for increasing the available water supply of drainage systems and restoring active water regulation on reclaimed lands in a changing climate.
The paper presents the results of the research on improving the available water supply of drainage systems in the humid zone of Ukraine in a changing climate. It was specified in the face of increasing water scarcity providing the optimal water regime regulation on drained lands is possible due to the increase in the available water supply of drainage systems. It can be achieved thanks to the accumulating capacity of reclaimed areas, namely usage of free soil capacity of the aeration zone and open canals, accumulation of water reserve volumes in storage tanks due to the accumulation of surface and drainage runoff.
Taking into account the design features of different types of drainage systems, existing water management technologies, characteristics of water sources and their close proximity to the drainage systems, the technological schemes of water intake from rivers and reservoirs, and its supply to the drained areas for irrigation needs were developed. In a face of increasing water scarcity, it is also expedient to apply resource-saving technologies to control the available water supply for crops.
</abstract>

Improving Water Supply Capacity of Drainage Systems at Humid Areas in the Changing Climate

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In many countries of the northern hemisphere during winter period ice forms appear on various water bodies, which results in significant changes of physical, chemical and ecological conditions. These changes are different in rivers, channels, lakes or once-through reservoirs. On the terrain of Poland ice always caused considerable problems affecting intensive inland navigation and other river use. These problems appeared especially on the Vistula River, which in 17th and 18th century was one of the most navigable rivers in Europe. The Vistula is the largest Polish river, which flows from the south in the Carpathian Mountains to the Baltic Sea in the north. It is the second largest river, after Neva, of the Baltic Sea catchment. The length of the Vistula is 1047 km and its catchment amounts to 194 thousand km2. The predominant part of the Vistula river basin (87%) is now on Polish territory and the remaining (13%) catchment is in Belarus, Ukraine and Slovakia. The course of the Vistula can be divided into three distinctly different sections: upper, middle and lower. These river sections have appropriate catchments with their tributaries. There are hydraulic structures on the main river course and on its tributaries which serve navigation, hydroenergy, flood protection, water supply and recreation. All over the Vistula catchment there are frequent floods during spring and summer time resulting from excessive precipitation but in winter caused by ice phenomena. Numerous flow problems appear especially along the lower Vistula course because of ice phenomena and they result very often in severe flood problems. The Vistula has a very variable time and spatial discharge, because of existing climate conditions over its catchment.
The aim of the paper is to present hydraulic and hydrologic characteristics of the Lower Vistula river with special emphasis on the management of this river section for navigation, hydroenergy, flood protection and water supply in view of ice phenomena appearing there. Information concerning changes of water characteristics due to various water temperatures are presented as well as on the formation of various forms of ice in flowing water. Numerous ice studies were carried out in Poland and especially on the Lower Vistula section as it was very ice prone and where many ice jams and ice-jam floods occurred. A special hydraulic situation existed at the mouth of the Vistula, which caused important floods in the 18th century and resulted in the construction of a special direct channel to the sea (Przekop Wisły) solving flood problems in this area. Information is presented on changes in open channel flow due to the appearance of ice cover and other ice forms. The paper includes ample information on the run, consequences and studies connected with a very important ice-jam-flood on the upper part of Włocławek reservoir in 1982.
</abstract>

The Lower Vistula and Its Ice Problems

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Archives of Hydro-Engineering and Environmental Mechanics

 Archives of Hydro-Engineering and Environmental Mechanics (formerly Archives of Hydro-Engineering and Archiwum Hydrotechniki) cover the broad range of research disciplines related to hydro-engineering, including: hydrodynamics and hydraulics of inlands and sea waters, hydrology, hydroelasticity, ground-water hydraulics, water contamination, coastal engineering, geotechnical engineering, geomechanics and structural mechanics.  The main objective of Archives of Hydro-Engineering and Environmental Mechanics is to provide an up-to-date reference for civil engineers and scientists involved in the applications of mechanics to the analysis of various phenomena encountered in the natural environment, those occurring due to human activities, as well as to the problems arising from the influence of the environment on man-made structures and objects. Theoretical, experimental and practice-oriented papers on various topics, such as those mentioned above, are welcomed. Review papers are also invited. Occasionally, special issues containing papers presented at international conferences and other scientific meetings may be published.  All papers (in regular and special issues) are selected for publication through a peer review process, based on their significance and research originality.  Archiving  Sciendo archives the contents of this journal in Portico - digital long-term preservation service of scholarly books, journals and collections.  Plagiarism Policy  The editorial board is participating in a growing community of Similarity Check System's users in order to ensure that the content published is original and trustworthy. Similarity Check is a medium that allows for comprehensive manuscripts screening, aimed to eliminate plagiarism and provide a high standard and quality peer-review process. 