Concept design for flood protection of the City of Novigrad based on blue-green infrastructure

Abstract

U ovome radu prikazano je idejno rješenje zaštite Grada Novigrada od štetnog djelovanja voda primjenom plavo-zelene infrastrukture. Na početku rada dan je opis područja i planiranih faza urbanizacije područja Grada Novigrada te pregled klimatskih i oborinskih karakteristika. Analizirani su infrastrukturni sustavi grada te je prikazano trenutno stanje kanalizacijskog sustava. U radu je generiran pljusak za projektiranje za područje Grada Novigrada kako bi se dobili realni podaci o oborinama. U QGIS alatu napravljena je analiza pokrova zemljišta, udjela nepropusnih površina uz primjenu CN vrijednosti prema SCS metodi za povijesno, trenutno i buduće stanje izgrađenosti područja. Na temelju hidrološko – hidrauličkih analiza provedenih u SWMM 5.1. programu prikazano je povećanje otjecanja oborinskih voda kao rezultat povećanja nepropusnosti podloge zbog intenzivnije izgrađenosti područja. Stoga je predložen koncept smanjenja otjecanja i zaštite od štetnog djelovanja velikih voda primjenom plavo-zelene infrastrukture prema LID pristupu (zeleni krovovi i infiltracijska retencija – kišni vrt).This paper presents the conceptual design for the flood protection of the City of Novigrad by applying blue-green infrastructure. First a description of the area and planned phases of urbanization of the area of the City of Novigrad is given, as well as an overview of climate and precipitation characteristics. The infrastructural systems of the city are analyzed and the current state of the sewerage system is shown. A design storm was generated for the City of Novigrad to define a more realistic precipitation data. Next, the land cover was analysed using QGIS tools, and the corresponding CN number according to the SCS method was assessed for the past, present and future conditions. Hydrological - hydraulic analyses performed in SWMM 5.1. showed an increase in the precipitation runoff as a result of a higher percentage of impermeability of the area because of an increased urbanisation. Therefore, a concept design was proposed for reducing the precipitation runoff and flood protection by implementing blue-green infrastructure according to the LID approach (green roofs and an infiltration retention - rain garden)