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Potencjalna zdolność retencyjna obszarów leśnych nadleśnictwa doświadczalnego "Siemianice"

100%

Krysztofiak A. , Grajewski S.

tom Nr 18

230-231

Investigation of the influence of hydrogel amendment on the retention capacities of green roofs

63%

Deska I. , Mrowiec M. , Ociepa E. , Łacisz K.

Ecological Chemistry and Engineering. S

2018

tom Vol. 25, nr 3

373--382

Progressive economic development as well as urbanisation influence the characteristics of the stormwater runoff. Progressive sealing of drainage basin surface prompts the decrease of rainwater infiltration, thus increasing the runoff intensity. This results in an increase of flood risk. Thus, in urban areas the sustainable urban drainage systems (SUDS) are used in addition to the traditional sewer systems. The examples of SUDS strategy are, inter alia, the roofs covered with vegetation (the green roofs). The paper presents the results of research of retention capacities of 4 diverse green roof models with following growing media: (1) the typical green roof substrate without any additions, (2) the substrate with addition of about 1 % by weight of hydrogel (the cross-linked potassium polyacrylate), (3) the substrate with addition of about 0.25 % by weight of hydrogel, (4) the substrate with addition of expanded clay and perlite. The models did not have the vegetation layers in order to explore only the retention capacities of drainage layers and substrates. The aim of the first part of research was to investigate the retention capacities of green roof models after 1, 2, 6, 8 and 10 antecedent dry days. In the case of 1 and 2 antecedent dry days the best medium retention capacity had green roof model 2 (with substrate with addition of 1 % by weight of hydrogel), and the weakest medium retention capacity had green roof model 1 (without any additions). In the cases of precipitations which occurred after 6 as well as 8 and 10 antecedent dry days the best retention capacity had green roof model 3 (with addition of about 0.25 % by weight of hydrogel). The weakest retention capacity had in these cases green roof model 4 (with addition of expanded clay and perlite). The aim of the second part of research described in the paper was to investigate the retention capacities of green roof models during precipitations that occurred after long antecedent dry periods of time (34, 59 and 106 antecedent dry days). The substrates and drainage layers were air-dry directly before precipitations. The best retention capacity had in this case green roof model 3 (with the substrate with addition of about 0.25 % by weight of hydrogel). The second largest retention capacity had model 2 (with the substrate with addition of about 1 % by weight of hydrogel). The definitely weakest retention capacity had model 4 containing the substrate with addition of expanded clay and perlite. The results may indicate that the efficacy of hydrogel decreased over time probably due to its decay under the influence of solar radiation.

Ocena zdolności retencyjnej kolektora kanalizacyjnego

51%

Skotnicki M. , Sowiński M.

Czasopismo Inżynierii Lądowej, Środowiska i Architektury / Journal of Civil Engineering, Environment and Architecture

2014

tom z. 61, nr 3/I

265--283

W artykule poruszono temat redukcji szczytowego odpływu oraz opóźnienia czasu jego wystąpienia w wyniku spiętrzenia wód opadowych w kolektorze kanalizacyjnym. Zagadnienie było rozpatrywane na przykładzie istniejącego kanału o średnicy 1,0 m, długości 968 m i spadku 1,6o/oo. Model opad-odpływ wykonany w programie SWMM5 został wykorzystany do generacji odpływu wywołanego deszczem symulowanym przez blokowe hietogramy o różnej intensywności opadu. Piętrzenie przepływu w kolektorze było modelowane za pomocą przewężenia poniżej analizowanego odcinka. Stwierdzono, że w rozważanym przypadku zdolności retencyjne kolektora zależą niemal wyłącznie od objętości fali odpływu. W zależności od średnicy przewężenia istnieje możliwość redukcji odpływu szczytowego przy piętrzeniu nie powodującym wypływu ścieków na powierzchnię terenu, dla objętości fali spływu wód opadowych do 8 razy większej od użytecznej pojemności kanału.

The paper deals with a problem of peak flow reduction and a delay of its appearance time by detention of runoff in a sewer main. The problem has been investigated for an existing sewer main characterized by the following parameters: the diameter 1.0 m, the length 968 m and the slope 0.16 %. A rainfall-runoff model implemented in the computer program SWMM5 has been used for simulation of runoff from the sewer catchment which had been generated by block rainfalls of different intensity. The runoff detention in the sewer has been realized by reduction of its diameter downstream the modeled reach. It has been found, that in the presented case study retention ability of a sewer depends mainly on a volume of outflow wave. Depending on a diameter of reduced section of a sewer the possibility of peak flow reduction without an outflow on the ground surface for a volume of runoff wave exceeding up to 8 times free capacity of sewer exist.