No verão do ano 2000, um evento extremo de chuva ocorreu em Campos do Jordão, causando deslizamento de encostas em vários pontos da área urbana, em bairros considerados de risco. Este evento provocou a morte de 10 pessoas e um saldo de aproximadamente 3000 desabrigados. Os impactos ambientais e sociais desse acontecimento foram catastróficos. A ocupação de encostas, de maneira geral, é feita de maneira desordenada onde se verifica a remoção da vegetação existente para a construção das moradias de baixo padrão, processo que altera a morfodinâmica local e traz implicações para a própria população.No caso específico de Campos do Jordão, houve um grande crescimento da ocupação das encostas entre os anos de 1986 e 2003, principalmente nas áreas com declividade superior a 45 áreas consideradas de alto risco para a construção de moradias mas que mesmo assim, são invadidas e ocupadas irregularmente. A partir do evento de chuvas/deslizamentos ocorrido no ano 2000, a Prefeitura Municipal de Campos do Jordão passou a intervir, de forma mais intensa e sistematizada, na busca de soluções para gestão das áreas de risco, por exemplo, com a aquisição de áreas para formação de loteamentos onde serão vendidos terrenos para as famílias que ocupam as áreas de risco muito alto. / On the 2000 Summer, an extreme rain event occurred in Campos do Jordão, causing landslide of the slopes in several points of the urban area in places considered on risk.This event causes the death of ten people an approximately 3000 (three thousand) homelesses. The social and environment impacts of this event were catastrophic. The occupation of the slopes, in general, is made in a disorganized way where it checked the removal of the existing vegetation for houses building, process that changes the morfodynamic local and brings implications to the own population. In the specific case of Campos do Jordão, there was a great increasing of the slopes occupation between 1986 and 2003, mainly in areas with superior slopes up 45 considered as high risk to the dweeling construction even so, are irregulary invaded and occupated. From the landslides/rain events onwards occurred on 2000, the Municipal Prefectures of Campos do Jordão, started to intervene on a systematic and intense way, in search of solutions for management of risk areas, for example, with the acquisition of areas to form portions that will be saled on pieces to the families that occup very high risk areas.

The purpose of this study was (1) to study the proportion (X) of the flow in a watercourse that consists of urban runoff during a rain event and (2) to evaluate the risk that a few chosen pollutants, transported by urban runoff, exceed the maximum allowed concentration in the watercourse according to the environmental quality standards (MAC-EQS). The Fyris river in Uppsala, Sweden, was selected as a case study. Urban runoff quickflow was estimated with a water balance model using precipitation data and flow data from three stations. Precipitation data was used to identify 31 rain events with a minimum rain volume of 10 mm and at least a maximum rain intensity of three mm/h during the study period 2017-2020. Pollutants in urban runoff were sampled during the winter of 2020-2021. The highest concentrations obtained during sampling were used to estimate momentary pollution concentration and to evaluate the risk of exceeding MAC-EQS. The highest X found during a rain event was 71%. Low flow conditions in the river prior to a rain event in summertime are circumstances when X can be expected to be high. It is therefore advised to include rain events under such circumstances when monitoring MAC-EQS or sampling momentary pollution concentrations in the Fyris river. The pollutant category polycyclic aromatic hydrocarbons (PAH), and especially the pollutant fluoranthene, showed risk of momentary pollution concentration exceeding MAC-EQS. Therefore, the author recommends that future studies of urban runoff should include PAHs. / Syftet med denna studie var (1) att studera hur stor andel (X) av flödet i ett vattendrag som utgörs av dagvatten vid ett regntillfälle, och (2) att utvärdera risken att ett utvalt antal föroreningar som transporteras med dagvattnet överskrider maximal tillåten koncentration enligt miljökvalitetsnormerna för vatten (MAC-MKN). Fyrisån i Uppsala, Sverige, valdes som fallstudie. Snabbt dagvattenflöde (quickflow) uppskattades med en vattenbalansmodell som använde nederbördsdata samt vattenföring från tre stationer. Nederbördsdata användes för att identifiera 31 regntillfällen med en minsta regnvolym på 10 mm och minst en maximal regnintensitet på tre mm/h under perioden 2017-2020. Föroreningar i dagvatten provtogs under vintern 2020-2021. De högsta koncentrationerna som påträffades vid provtagningen användes för att uppskatta momentan föroreningskoncentration och för att utvärdera risken att MAC-MKN överskrids. Det högsta X som beräknades under ett regntillfälle var 71%. Lågt flöde i Fyrisån innan ett regntillfälle under sommartid är omständigheter när X kan förväntas vara högt. Det rekommenderas därför att inkludera regntillfällen under sådana omständigheter när MAC-MKN övervakas eller när momentana föroreningskoncentrationer i Fyrisån provtas. Föroreningskategorin polycykliska aromatiska kolväten (PAH), och särskilt föroreningen fluoranten, uppvisade risker för att MAC-MKN skulle överskridas. Därför rekommenderas att framtida studier av dagvatten bör inkludera PAH:er.