Water infiltration into the soil – what do measurements indicate?

Physical properties of top-soil organic materials significantly influence initiation processes of infiltration and runoff generation. This paper deals with the specifics of water infiltration through the top surface organic layer of the forest soil. Three field methods (Guelph permeameter, Tension disk permeameter, Single-ring method) and one laboratory method (Falling head) of hydraulic conductivity (KS) determination are compared and interpreted in the context of their applicability and limitations. The Falling head method provides far different values of KS if sample cylinders are or are not sealed with grease against the wall effect. The Guelf permeameter is very significant to the position of different horizons’ interface, while Tension disc permeameter results are dependent on antecedent soil moisture. The single ring method is applicable with acceptable results only when there is no abrupt interface between horizons in the vicinity of the ring bottom edge

Assessment of river bed evolution with the aid of 2D hydrodynamic model with integrated sediment transport modeling capabilities

The aim of the study is to assess hydro-morphologic evolution of currently cut off meander for 3 river restoration scenarios during 10 days of bank-full discharge. To simulate hydro-morpho-dynamics, a numerical model with movable bed, R2DM is used. Results for scenario with partially opened meander indicate aggradation at inlet of meander and 10% decrease in flow rate. Scenario with fully opened meander shows aggradation at the inlet and 55% decrease in flow rate. Full diversion scenario results in formation of natural river landforms (point bars, cut banks, pools, riffles) and stabilization of river bed evolution

Spatiotemporal variability of hydrologic soil properties and the implications for overland flow and land management in a peri-urban Mediterranean catchment

Planning of semi-urban developments is often hindered by a lack of knowledge on how changes in landuse affect catchment hydrological response. The temporal and spatial patterns of overland flow source areas and their connectivity in the landscape, particularly in a seasonal climate, remain comparatively poorly understood. This study investigates seasonal variations in factors influencing runoff response to rainfall in a peri-urban catchment in Portugal characterized by a mosaic of landscape units and a humid Mediterranean climate. Variations in surface soil moisture, hydrophobicity and infiltration capacity were measured in six different landscape units (defined by land-use on either sandstone or limestone) in nine monitoring campaigns at key times over a one-year period. Spatiotemporal patterns in overland flow mechanisms were found. Infiltration-excess overland flow was generated in rainfalls during the dry summer season in woodland on both sandstone and limestone and on agricultural soils on limestone due probably in large part to soil hydrophobicity. In wet periods, saturation overland flow occurred on urban and agricultural soils located in valley bottoms and on shallow soils upslope. Topography, water table rise and soil depth determined the location and extent of saturated areas. Overland flow generated in upslope source areas potentially can infiltrate in other landscape units downslope where infiltration capacity exceeds rainfall intensity. Hydrophilic urban and agricultural-sandstone soils were characterized by increased infiltration capacity during dry periods, while forest soils provided potential sinks for overland flow when hydrophilic in the winter wet season. Identifying the spatial and temporal variability of overland flow sources and sinks is an important step in understanding and modeling flow connectivity and catchment hydrologic response. Such information is important for land managers in order to improve urban planning to minimize flood risk

Mikroskopická variabilita hydraulických vlastností půdy v borovicovém lese u obce Sekule na jihozápadě Slovenska

The variability of water repellency of pine-forest arenic Regosols and its influence on the infiltration process were estimated at the locality of Mláky II near Sekule in south-west Slovakia. The water drop penetration time (WDPT) tests of soil water repellency and infiltration tests with a miniaturized tension infiltrometer (3 mm diameter) at single-sample scale (100 cm3 volume, 22 cm2 surface) were performed. Extreme heterogeneity of water repellency and infiltration velocity was recorded. All the results suggested that the hydraulic properties of the soil are changing at millimetre scale due to the presence of unevenly distributed hydrophobic material

Air Entrainment and Free Surface Modeling of Fully Turbulent Flow Near the Broad-Crested Weirs

The research was carried out at the Department of Hydraulic Engineering, Faculty of Civil Engineering, Slovak University of Technology in Bratislava with close cooperation with Institute of Water Structures, Faculty of Civil Engineering, Brno University of Technology. One of the important goals was the determination of the most accurate approach related to the computational fluid dynamics modeling of the air-water interaction. Research consists of two main research methods to ensure the accuracy, set up the possibilities of cooperation and the results control. The first method was the physical model of broad-crested weir installed in collapsible canal in hydraulic laboratory and the second was numerical computational fluid dynamics model of broad-crested weir created in same scale. In free surface flows the air entrainment phenomena plays an important role. Air entrainment is affecting the volume fraction, velocity field, energy dissipation and many other parameters related to dynamic behavior of water near the crests. Different approaches were carried out to identify most accurate computational fluid dynamics setup compared to physical model measurements. Compared results and the accuracy assessment are summarized and the best computational fluid dynamics parameterization is recommended

Non-Intrusive Bedload Granulometry Using Automated Image Analysis

This paper presents a proprietary open source code for analysis of granulometric properties of bed load material based on non-intrusive automated image analysis. Vertical bedsurface images are processed using the proposed tool and verified with results obtained by well tested optical granulometry tool Basegrain. The practical application of the proposed tool yields accuracy comparable that of the tested framework and traditional sampling methods. Additionally, results showed that the average D50 grain-size sampled from riverbed of studied river section of river Danube agrees up to 95% with the average D50 sampled from riverbanks

Flow over broad-crested weir with inflow by approach shaft – numerical model.

In the case of flow over rectangular broad-crested weir, where the inflow is realized by approach shaft, occurs influence of water surface level by approach flow velocity. The paper describes numerical model of flow including weir, approach and outlet shaft. Simulations of flow were created by 2D and 3D model with using three methods of turbulent modelling. In paper is evaluated water surface level for each model setup and then is compared with measured values

Interaction of Brilliant Blue dye solution with soil and its effect on mobility of compounds around the zones of preferenial flows at spruce stand

We performed field experiment with 10 g l−1 concentration of Brilliant Blue solutes in 100 l of water sprinkling on 1 × 1 m surface of the Dystric Cambisol. Consequently, four vertical profiles were exposed at experimental plot after 2 hours (CUT 2), 24 hours (CUT 24), 27 hours (CUT 27) and after 504 hours (CUT 504) in order to analyse spatiotemporal interactions among the BB solution (Na-salts), soil exchangeable complex and fine earth soil (%) samples extracted from both the high and low coloured zones located around the optically visualised macropore preferred flow (PF) zones. The concentration changes were quantifying via soil profiles not affected by BB (termed as REF) located in the close vicinity of experimental plot. Observed changes in pH (H2O), chemical composition of fineearth soil, as well as in concentration of Na+ in soil exchangeable complex to suggest, the BB dye solution didn’t represent an inert tracer, but compounds strongly involved in reaction with surrounding soils. Recorded chemical trends seems to be the result both the competitive processes between the Na+ of BB dye solution and composition of surrounding soil exchangeable complex, as well and the spatial-temporal controlled mechanism of dye solution transfer in soil

Measures for Flood Discharge Transformation on the Ondava River

The contribution is dealing with run-off conditions on the lower part of the Ondava River as the capacity of the river bed is insufficient at high flow rates. The reason for the proposed research was the flood situations when protection dikes were breached. For mathematical modeling of flood wave progress, the HEC-RAS software has been applied coupling 1D and 2D modeling procedures. Results of the mathematical model of the surface water level regime in the Ondava River were compared with measured values and afterwards it was used to design further flood protection measures utilizing the existing drainage channel system and pumping stations, as well