Assessment of contemporary state of a fluvial system requires recognition of a relationship between transport capacity, channel morphology and sedimentological properties of a bedload and its hydraulic effect. The objectives of study are: (1) to describe relationship  between pebble shape and orientation, and cluster bedforms visible on a surface of emerged channel bars, and (2) to provide an answer on question, whither textural properties of gravel bedload can help estimate channel stability, and dynamics of sedimentary environment (in a given channel reach). The measurements we done in a few chosen sections of two mountain streams – Rycerka and Danielka, in Beskid Żywiecki (South Poland). On a surface of emerged channel bars, at first was made photographic documentation of pebble cluster, and then pebble orientation and shape was measured in fractions: 30–50, 70–100, 150–170 and 200–250 mm. The bed material is composed of a range of oblate and prolate gravel size particles. Sparse boulders and cobble size material usually prevent its orientation form the transportation phase and remain immobile during most flows (or smaller flood events, also). These particles initiate development of other sedimentary structures, i.e. obstacle clasts. The orientation of particles with a-axis transverse to flow is associated with traction carpet and indicates a high bedload transport rate and quite abrupt deposition. Particles of 70–100 mm were imbricated (a-axis parallel to flow). During transport, that particles move by sliding or in saltation, but even slight decrease of flow can cause its settling, and reorientation. Typical imbrication developed on a side of channel bars. Unclustered bedforms (i.e. open bed non-interlocked) were located in middle and distal part of channel bars and build with finer particles: pebbles and granules. Their orientation was plane or chaotic. Due to the low flow we can assume that they prevent its position from transportation phase. This study showed that orientation of particles and their arrangement in characteristic sedimentary structures is highly dependent on lithology of bed material. Flat and elongated pebbles (abundant in investigated streams) are most susceptible to form imbrication, and clustered bedforms, like: obstacle clasts or complex clusters. Such sedimentary structures can develop very quickly, and hence increase stability of gravel-bed stream.

European Water Framework Directive requires hydromorphological evaluation of rivers as a supportive element of ecological status assessment of running waters. River Habitat Survey is widely used method for estimation of hydromorphological characteristic of watercourses that arise from the aggregated view on river corridor and possibility of stastistical analysing. The results of surveys carried out on Polish lowland rivers in the years 1997–2008 allowed to conclude that RHS can be used in our country.

Paper presents the analysis of consequences of hypothetical breach of Przeczyce storage reservoir earth dam, located on Czarna Przemsza river (Silesia). The studies were divided on two essential parts. In the first one the process of dam body wash-out applying computer program Dam-Breach has been analysed, assuming dam crest overflow as probable cause of failure. Time duration of dam body washing out, breach parameters and outflow have been determined. In the second part the conditions of hypothetical flood wave routing along the river Czarna Przemsza valley have been analysed applying computer program Dam-Break. Velocity and flood wave passage time have been determined. Results of calculations have been plotted on topographic maps, on which the potential threat zones related to time of wave reach to an analysed cross-section have been marked too. On the basis of calculations, for area located along the flood wave course caused by a hypothetical dam failure, the information and warning system has been proposed.

In the paper are presented the most important results of laboratory and field investigations concerning of sandy bedload characteristics in aspects of initiation of motion and variability of bedload discharge in small lowland river, i.e. in steady and unsteady flow conditions. Investigations of critical shear stress have been carried out in laboratory flume with flat movable bottom formed by sands with different grain-size distributions. The characteristics of bedload discharge variability are presented on the basis of field investigation results conducted in the Zagożdżonka riverbed. The bedload trap provided with devices for continuous measuring and data recording was used in field investigations.

An improperly designed hydroengineering constructions are the cause of many failures of hydraulics structures. The design solutions are verified in the physical models for emergency load conditions and in order to optimize complex shapes in the case of large hydroengineering constructions. The authors presented the research process of the designed weir at the inlet to flood channel Odra-Widawa with the aim of verifying the conditions for transmission of flood waters. The check of designed shapes of weir elements and efficiency of energy dissipation in the stilling basin according to the desired water levels was performed. Using vortex method the preliminary analysis of the water inflow into the weir were performed for determining the geometry of the model. Then tests on the physical model of the “fish-belly” flap were done to verify the assumptions adopted in the project and formulated conclusions and recommendations to the weir project.

In this paper the changes of the Ner River capacity are analyzed. The last changes are the direct results of river training done in 2007. The regulation was done due to the requirements of Voivodeship Board of Water Reclamation in Konin. The training consist of mud removal of the Ner River reach of length 20 km. This is the reach from the Ner junction with the Warta River to the border of Great-Poland. The increase of river capacity is important for reduction of the flood risk in the region. The changes of river capacity are also important from the environmental point of view. The Ner Valley, as part of Great-Valley of Bzura and Ner, is a part of Natura 2000 network since 2004. These are the most valuable wetlands of central Poland. Since any human impact on the river may be the reason of the ecosystem degradation. The mentioned issues show that the Ner River problems may be investigated form two different points of view: technical and environmental. Theoretically, this may be a reason of conflicts caused by divergent requirements imposed on the watershed existence.