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Large-scale changes of the forestation in river channel below the dams in Southern African rivers: assessment using Google Earth Images

Uddin F. M. J., Asaeda T., Rashid M. H.

Polish Journal of Ecology

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2014

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Vol. 62, nr 4

607--624

EN

According to the results of many studies construction of dams, their decommissioning, and sediment flushing from the reservoir have been associated with vegetation dynamics. However, factors governing the spatial changes of forestation in the floodplain below the dams have not been explored extensively. This study examined the interacting effects of dam, inflow and land-use patterns of catchment areas and other factors on downstream vegetation patterns along the downstream reaches of Southern African Rivers. A total of 105 segments of 15 rivers (16 dams) located in seven Southern African countries were studied. Areas of herbaceous and forest vegetation of river channels below a dam and land-use catchment area patterns were obtained by the Google area calculator and aerial image analysis. Forest development was the highest just below the dams, and the ratio of forest cover decreased with distance from the dam toward the river mouth. Forest coverage ratio was found to decrease with an increase in dyke distance, number as well as of inflows (r = −0.66, P <0.01) and water coverage ratio, and bare land in the river flood plain. However, a principal component analysis (PCA) showed that the proportion of bare land in the catchment area, the dyke distance of the river and the number of inflows or tributaries are the factors most associated with forestation among the studied parameters. Forestation progressively decreased following the entrance of free following tributaries below dams, which appeared to reduce the effects produced by dams on vegetation forestation by causing local deviation. The impact of different land use types, such as agriculture on forestation, was insignificant though in some cases, land use areas cause the forest area reduction.

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Wykorzystanie NMT w analizie obszarów zalewowych

Sanecki J., Pabisiak P., Bauer R., Ptak A., Stępień G.

Zeszyty Naukowe Politechniki Rzeszowskiej. Budownictwo i Inżynieria Środowiska

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2012

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z. 59, nr 1/II

287-293

PL

Artykuł przedstawia analizę dokładności NMT w określaniu wielkości przewyższeń oraz jego zastosowanie do szacowania obszarów zalewowych oraz widoczności między punktami. Przedstawiono możliwości wykorzystania danych wysokościowych pochodzących ze skaningu laserowego na tle numerycznego modelu terenu w formacie DTED, z którego powszechnie korzysta polska armia. Autorzy wykonali również pomiary terenowe w celu określenia dokładności analizowanych modeli wysokościowych. Dane LiDAR wykorzystane w artykule obejmują swym zasięgiem teren nadodrza w miejscowości Uraz k. Wrocławia. Skaning laserowy wraz z NMT i NMPT wykonała tarnowska firma MGGP Aero w dniu 13 lipca 2010 roku. Do analiz wielkości terenów zalewowych autorzy wykorzystali aplikacje ArcGIS.

EN

The article presents the analysis of precision of digital terrain models (DEM, DSM) in defining the size of superiority (drop) and its application to estimate flooded areas as well as visibility between points. The usability of utilization of observed, sourced (height) elevation data coming from LiDAR is shown on background of Digital Terrain Elevation Data (DTED) which is use generally by Polish Armed Forces. Authors conducted also the terrain measurements to define the precision of analyzed digital terrain models. LiDAR data used in article include terrain close to the Odra river in the Uraz locality near to the Wroclaw City. LiDAR, DEM and DSM data were prepared by MGGP Aero Company and received on the 13th of July 2010. To analyses of size of flooded areas authors applied ArcGIS software.

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Relationship between nematode community and biomass and composition of periphyton developing on artificial substrates in floodplain lake

Vidakovic J., Palijan G., Cerba D.

Polish Journal of Ecology

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2011

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Vol. 59, nr 3

577-588

EN

Periphyton colonisation on artificial substrate (microscopic glass slides) was investigated from July to November 2007, in Lake Sakadas (Danube River floodplain Kopacki rit, Croatia). Two different stations were chosen due to different post - flood conditions. The aim of the study was to follow temporal changes of nematode community composition and trophic structure in relation to periphyton biomass and bacterial abundance. In bryozoan - dominated periphyton (Plumatella emarginata Allman, 1844) nematodes were represented by 86 and 87% of total associated invertebrate fauna at S1 and S2 respectively. Total nematode abundance (up to 600 ind. 10 cm[^-2] at one station and up to 1130 ind. 10 cm[^-2] at another station) correlated significantly with the abundance (meaured as CFUs - colony forming units) of copiotrophic and oligotrophic bacteria at one station (r = 0.963, 0.998, P <0.05) and with organic and inorganic content of periphyton at another station (r = 0.891, 0.899, P <0.05). Nematode trophic groups (epistrate feeders, chewers, detritus feeders and suction feeders) were equally developed at both stations except detritus feeders whose species richness and abundance were significantly higher at the S1. Epistrate feeders were the most abundant trophic group in nematode assemblages at both stations with Chromadorina bioculata being the dominant species. Change in dominance of epistrate feeders by chewers (Brevitobrilus stefanskii) and suction feeders (Crocodorylaimus sp.) coincided with the occurrence of flood pulse. Effect of flood pulse on nematode community structure was probably indirect, alterating concentration of dissolved oxygen which chromadorids are sensitive to. The structure of nematode community developed through time differs between investigated stations indicating high sensitivity to bacterial abundance, periphyton biomass and P. emarginata mats which made the habitat more diverse and patchy.

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Poldery w ochronie przeciwpowodziowej na przykładzie dorzecza górnego Renu i Odry

Baran-Gurgul K.

Czasopismo Techniczne. Środowisko

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2004

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R. 101, z. 15-Ś

3--21

PL

W artykule zawarto podstawowe informacje o rodzajach i znaczeniu polderów stosowanych w ochronie przeciwpowodziowej. Zaprezentowane w nim informacje uzyskano na podstawie przeglądu i analizy systemu ochrony przeciwpowodziowej górnego Renu i Odry.

EN

The paper presents some information on different kinds of polders used in flood protection in the upper Rhein and Oder river valley.