A. Kotowski

Probabilistic Models of Maximum Precipitation for Designing Sewerage

AbstractPluviographic measurement results from the Institute of Meteorology and Water Management (IMGW) Wroclaw–Strachowice meteorological station from the years 1960–2009 constitute the basis for this paper. While conducting the statistical analysis of precipitation occurrence frequency, the criterion of interval precipitation amounts was assumed in order to isolate the intensive rainfalls from the pluviograms, which made it possible to select a number of the most intensive rainfalls in each year. A total of 514 synthetic rainfall instances were isolated, which were then were arranged according to non-increasing amounts in 16 duration intervals. This was the basis to propose the unification of the development methodology of probabilistic models for maximum precipitation amounts, reliable in the designing and verification of drain flow capacity, especially for low probability of precipitation occurrence. Maximum precipitation models for Wroclaw were developed (average annual precipitation H = 590 mm).

Sizing and Modeling of the Sewage System in the City of Wroclaw / Wymiarowanie I Modelowanie Kanalizacji Deszczowej We Wrocławiu

Abstract The paper presents verification of selected flow time methods in terms of usability for sewage systems design and sizing on the example of a model municipal flat drainage area of the area of 2 km2. Namely, the sewage system network was sized using three methods, that is, MGN with Błaszczyk’s formula, MGN with the precipitation model for WROCLAW and MWO with the precipitation model for Wroclaw, and then, the network functioning was verified for damming up on the area surface and flooding from drains using the hydrodynamic model SWMM 5.0. The precipitation model of Euler type II was used as the drainage area load in the conditions of Wroclaw, for which the probabilistic model of the maximum precipitation was developed. It was shown that the safe flow time method for sewage system sizing is MWO using the criterion for the lack of damming up for the area and flooding from drains. Abstrakt W pracy symulowano działanie kanalizacji deszczowej zwymiarowanej trzema metodami czasu przepływu, tj.: MGN z wzorem Błaszczyka, MGN z wzorem opadów dla Wrocławia i MWO z wzorem opadów dla Wrocławia, dla modelowej zlewni miejskiej o powierzchni 2 km2 w terenie płaskim. Do symulacji hydrodynamicznych systemów kanalizacyjnych wybrano program SWMM 5.0 (Storm Water Management Model), opracowany przez Amerykańską Agencję Ochrony Środowiska (US EPA). Jako obciążenie zlewni zastosowano opad modelowy Eulera typ II w warunkach hydrologicznych miasta Wrocławia (rzędna terenu 120,0 m nad poziom morza). Wskazano na bezpieczną metodę wymiarowania systemów kanalizacyjnych (MWO) przy kryterium braku wylewów z kanałów.