Afstrømning fra ubefæstede arealers påvirkning på afløbssystemet

Abstract

I dette kandidatspeciale undersøges overfladeafstømning under danske jordforhold, for at vurdere påvirkningen på afløbssystemet. Analysen er opdelt i fem trin inputparametre, afstrømningsmodel, overfladeafstrømning, afløbsmodel og påvirkning på afløbssystem. I første trin undersøges inputparametrene, hvor der tages udgangspunkt i både danske og amerikanske jordprøver samt jordprøver fra et caseområde placeret i Lystrup. Der tages udgangspunkt i caseområdet i Lystrup, da overfladeafstrømning og jordforhold er registreret. Anden trin er opstilling af en dynamisk afstrømningsmodel, som beregner infiltrationshastighed i den umættede zone. Afstrømningsmodellen kalibreres op imod registreret afstrømningsdata fra Lystrup, og benyttes til at undersøge overfaldeafstrømning under danske jordforhold, hvilket er tredje trin i analysen. I fjerde trin opsættes afløbsmodellen over caseområdet i Lystrup. Afløbsmodellen modificeres så de ubefæstede arealer inkorporeres, og kan defineres ud fra resultatet af afstrømningsmodellen. Det femte og sidste trin vurderes påvirkningen af afløssystemet ud fra ændringer af afløbssystemets funktionspraksis ift. en referencemodel, hvor de ubefæstede arealer ikke bidrager til afløbssystemet. Undersøgelsen foretages i MIKE URBAN og viser at overfaldeafstrømning fra ubefæstede arealer har betydning for afløbssystemet.

In this Master thesis it's investigated how surface runoff from impervious areas impact the drainage system. The surface runoff is calculated under Danish soil conditions, to evaluate the impact on the drainage system in Denmark. The analysis is divided into five steps: input parameters, runoff model, surface runoff, drainage model and impact on drainage system. The first step is analysis of the input parameters which include both Danish and American soil samples as well as soil samples from a case area located in Lystrup. The case area in Lystrup is included because the surface drainage and soil conditions are registered here. Which make it possible to compare calculated runoff with measured runoff. Step number two is to set up a dynamic model out of the data from Lystrup. The dynamic model calculates the infiltration rate in the unsaturated zone to investigated the surface runoff. The runoff model is calibrated against recorded runoff data from Lystrup and used to investigate surface runoff from Danish soil conditions. This is step number three. Step number four in the analysis is to setup the drainage model for the case area in Lystrup. The drainage model is modified so the impervious areas are incorporate in the model. The impervious area is defined from the result of the runoff model. The influence of the drain system is step five in the analysis. The influence of the impervious areaas on the drainge system is analysis based on changes in the drainage system's functional practice vs. a reference model where the impervious areas doesn't contribute to the drainage system. The study has been carried out in MIKE URBAN and shows that surface runoff from impervious areas is importance for the drainage system to make sure it is calculated correct.

A master thesis from Aalborg University

Afstrømning fra ubefæstede arealers påvirkning på afløbssystemet

[Surface runoff from impervious areas impact on the drainage system]