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Quality of rivers: comparison of hydro-morphological, physical-chemical and biological methods

Gorzel M., Kornijów R., Buczyńska E.

Ecological Chemistry and Engineering. S

2018

Vol. 25, nr 1

101--122

The study was performed in five fourth-order tributaries of the Bystrzyca Lubelska River (Eastern Poland, Lublin Upland), differing in the degree of river-bed transformation and level of pollution. Hydro-morphological methods (descriptive method by Ilnicki and Lewandowski - IL, and index method by Oglecki and Pawlat - OP) and biological indices based on the composition of zoobenthos (Diversity - D, and index based on proportions between the density of Oligochaeta and Chironomidae - O/Ch) permitted distinguishing of four classes, from II to V. The distinguishing of only two quality classes (III and IV) was possible by means of physical-chemical methods and by benthic index BMWP_PL. Those two methods seem to show the lowest sensitivity to the spatial variability of the environment quality. The BMWP_PL index was the least sensitive to year-to-year environmental changes, and O/Ch was the most sensitive. Relatively high conformity was obtained between hydro-morphological assessments performed by means of the OP and IL methods. Results obtained by means of these tools weakly corresponded with the physical-chemical assessments. The latter assessments were the most similar to those obtained by means of the BMWP_PL (degree of similarity = 57%) and D (47%) indices, and considerably less in the case of O/Ch (36%). The BMWP_PL and D indices better corresponded with the results of the hydro-morphological assessment performed by means of the IL method than with those performed by means of the OP method while D index showed a reverse pattern. The O/CH index proved useful for the assessment of the degree of organic pollution of the river’s water, but not the sediments.

The formation of single-channel and multiple-channel rivers on large slopes

Misiura K., Czechowski L., Witek P., Bendiukova A.

Geological Quarterly

2016

Vol. 60, No. 4

981--989

We investigated the formation of different types of rivers depending on slope, total discharge, and grain size. Calculations were performed using numerical package CCHE2D, developed by the National Center for Computational Hydroscience and Engineering. The model is based on the Navier-Stokes equations for depth-integrated two-dimensional turbulent flow and the three-dimensional convection-diffusion equation of sediment transport. For each model we use the same river geometry, suspended load concentration, and bedload transport rate. We distinguish three types of rivers using two methods for classification (single-channel, multiple-channels and transitional). We found that the trend line for transitional rivers is an increasing function of Q in space (Q, d) and that for large S the number of multichannel rivers decreases.