This paper presents a methodology for estimation of hydrodynamic loads acting on the bottom and at the walls of a stilling basin of a stepped chute with converging walls, based on the pressure measurements at the selected points of a scale model. This is the first study of hydrodynamic loads for this type of structure, and the first one of the loads on the stilling basin walls in general. For selected flow discharges, step heights and hydraulic jump submergence ratio, the hydrodynamic pressures were measured at a significant number of points, providing the spatio-temporal distribution of relevant hydrodynamic loads. The most influential effect proved to be a convergence angle of the chute walls. Based on these measurements, appropriate regression expressions were proposed for predicting hydrodynamic loads. These expressions show good agreement with measurements, offering a reliable tool for the structural design of stepped spillway stilling basins.

The condition of the existing sewerage system, the mean value and extremes of hydraulic loads for dry and rainy weather, organic load and key parameters of wastewater quality are determined based on the analysis of the collected technical documentation related to the existing sewerage system, statistical data on the number of inhabitants connected to the sewerage system, questionnaires filled out by the public utility company and industrial enterprises, the results of flow measurements and sampling of wastewater and testing of its physico-chemical characteristics. The algorithm for calculating the input parameters relevant for the dimensioning of the future plant is then selected depending on the condition of the sewerage system and the planned reconstructions and extensions, demographic, as well as projections of economic development.

The continuous flow measurement on hydroelectric turbine units is conventionally carried out using the relative methods (mostly Winter-Kennedy), where the complex velocity field in flow cross section is replaced by a single measured quantity. On a physical model, mapping parameters are determined. The Winter-Kennedy method is most used, where this relative (index) flow quantity is obtained by measuring differential pressure. The measurement uncertainty of the determined flow using this method is usually significantly higher than the uncertainty of other relevant quantities for determining the optimal turbine operating conditions. To reduce the flow uncertainty, it is necessary to perform "absolute measurements" of the entire velocity field and determine the necessary corrections to the index method under real operating conditions. This is especially true for plants where disposition is different from one used on physical model, which is the case of “Đerdap 2” and recognized problem of skewed inflow. With the aim of better assessing the hydraulic efficiency of turbines and to collect data on the actual operating velocity distribution in the inlet section in front of trash-rack needed for planned revitalization works, an innovative system for absolute flow measurement has been designed and implemented. The moving frame was designed and installed at the turbine inlet, upstream from the trash-rack. The 15 electromagnetic (EM) sensors and two redundant acoustic Doppler sensors were installed on horizontal bar. Each sensor measures all three velocity components. The frame moves by lifting along the entire height of the flow section, allowing the entire velocity field to be scanned. The position of the frame is tracked by two encoders, while two pressure sensors are used to measure the water depth. Measurements are synchronized with the local SCADA system, so appropriate turbine operation data are also used. Considering the specificities of the measurement system itself with newly developed EM sensors, as well as hydraulic conditions, an adequate procedure has been developed to assess the uncertainty of the measured flow. This paper presents the measurement method and provides some measurement results on the units of the “Đerdap 2” hydroelectric power plant.

The results of two flow, sampling and laboratory analysis campaigns of wastewater indicated their high dilution by the intensive inflow of foreign water into the fecal sewage system, which is a major problem for the functioning of the future wastewater treatment plant, which would have to be significantly oversized. A two-day field testing campaign was carried out, which included inspection of manholes, Measurements of flow, electrical conductivity and temperature of water to determine whether there is an inflow of surface water or infiltration of groundwater, and to find the points and/or zones of the most intense inflow of foreign water. The site of the inflow of the previously unregistered stream was found and possible solutions to the problem were defined.