The purpose of the paper was to present selected techniques for the control of river flow and sediment transport computations with the programming language Python. The base software for modeling of river processes was the well-known and widely used HEC-RAS. The concepts were tested on two models created for a single reach of the Warta river located in the central part of Poland. The ideas described were illustrated with three examples. The first was a basic simulation of a steady flow run from the Python script. The second example presented automatic calibration of model roughness coefficients with Nelder-Mead simplex from the SciPy module. In the third example, the sediment transport was controlled by Python script. Sediment samples were accessed and changed in the sediment data file stored in XML format. The results of the sediment simulation were read from HDF5 files. The presented techniques showed good effectiveness of this approach. The paper compared the developed techniques with other, earlier approaches to control of HEC-RAS computations. Possible further developments were also discussed.

The main purpose of the present research is to develop software for reconstruction of the river bed on the basis of sparse cross-section measurements. The tools prepared should support the process of hydrodynamic model preparation for simulation of river flow. Considering the formats of available data and the requirements of modern modeling techniques, the prepared software is fully integrated with the GIS environment. The scripting language Python 2.7 implemented in ArcGIS 10.5.1 was chosen for this purpose. Two study cases were selected to validate and test the prepared procedures. These are stream reaches in Poland. The first is located on the Warta river, and the second on the Ner river. The data necessary for the whole procedure are: a digital elevation model, measurements of the cross-sections in the form of points, and two polyline layers representing an arbitrary river centerline and river banks. In the presented research the concept of a channel-oriented coordinate system is applied. The elevations are linearly interpolated along the longitudinal and transversal directions. The interpolation along the channel is implemented in three computational schemes linking different tools available in ArcGIS and ArcToolbox. A simplified comparison of memory usage and computational time is presented. The scheme linking longitudinal and spatial interpolation algorithms seems to be the most advantageous.

Ewelina SZAŁKIEWICZ, Tomasz DYSARZ, Tomasz KAŁUŻA, Albert MALINGER & Artur RADECKI-PAWLIK - ANALYSIS OF IN-STREAM RESTORATION STRUCTURES IMPACT ON HYDRAULIC CONDITION AND SEDIMENTATION IN THE FLINTA RIVER, POLAND, Carpathian Journal of Earth and Environmental Sciences, August 2019, Vol. 14, No. 2, p. 275 - 286; DOI:10.26471/cjees/2019/014/079

The purpose of the paper is to test forecasting of the sediment transport process, taking into account two main uncertainties involved in sediment transport modeling. These are: the lack of knowledge regarding future flows, and the uncertainty with respect to which sediment transport formula should be chosen for simulations. The river reach chosen for study is the outlet part of the Ner River, located in the central part of Poland. The main characteristic of the river is the presence of an intensive morphodynamic process, increasing flooding frequency. The approach proposed here is based on simulations with a sediment-routing model and assessment of the hydraulic condition changes on the basis of hydrodynamic calculations for the chosen characteristic flows. The data used include Digital Terrain Models (DTMs), cross-section measurements, and hydrological observations from the Dabie gauge station. The sediment and hydrodynamic calculations are performed using program HEC-RAS 5.0. Twenty inflow scenarios are of a 10-year duration and are composed on the basis of historical data. Meyer-Peter and Müller and Engelund-Hansen formulae are applied for the calculation of sediment transport intensity. The methodology presented here seems to be a good tool for the prediction of long-term impacts on water surface profiles caused by sediment deposition and erosion.

In this paper, the impact of maximum flow uncertainty on flood hazard zone is analyzed. Two factors are taken into account: (1) the method for determination of maximum flows and (2) the limited length of the data series available for calculations. The importance of this problem is a consequence of the implementation of the EU Flood Directive in all EU member states. The factors mentioned seem to be among the most important elements responsible for potential uncertainty and inaccuracy of the developed flood hazard maps. Two methods are analyzed, namely the quantiles method and the maximum likelihood method. The maximum flows are estimated for the Wronki gauge station located in the reach of the Warta river. This simple river system is located in the central part of Poland. The length of the available data is 44 years. Hence, the series of the lengths 40, 30 and 20 years are tested and compared with reference calculations for 44 years. The hydrodynamic model HEC-RAS is used to calculate water surface profiles in steady state flow. The Python scripting language is applied for automation of HEC-RAS calculations and processing of final results in the form of inundation maps. The number of trials for each factor is not huge to keep the presented methodology useful in practice. The chosen measure of uncertainty is the range of variability for maximum flow values as well as inundation areas. The estimated values stressed the great importance of the factors analyzed for the uncertainty of the maximum flows as well as inundation areas. The impact of the data series length on the maximum flows is straightforward; a shorter data series gives a wider range of variability. However, the dependencies between other factors are more complex. Hence, the application of methodology based on the simulation and GIS data processing for assessment of this problem seems to be quite a good approach.