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abstract 736

STRATEGIES FOR URBAN DRAINAGE CHARGE IN PORTO ALEGRE – RS – BRAZIL

Author(s): Francisco rossarolla Forgiarini, Christopher Freire Souza, André Luiz Lopes da Silveira, Geraldo Lopes da Silveira, Carlos Eduardo Morelli Tucci
PhD Student Institute of Hydraulic Research – IPH, Federal University of Rio Grande do Sul – UFRGS, CNPq Grant Holder – Brazil. Address: Barão do Amazonas, 1157/38, 90670-004, Porto Alegre – RS – Brazil, Telephone +55 51 33 08 63 27, Fax +55 51 33 08 75 0

Keyword(s): urban drainage charge, low impact development, Porto Alegre - RS - BR

Article:

Poster:

Session: Poster session 4

AbstractIn recent decades, Brazilian cities have exhibited an accelerated and unplanned process of

urbanization, thereby producing negative impacts on water systems. Mechanism for encouraging the reduction of this

impact have been studied and implemented, taking as reference charges for the urban drainage service. The aim of

the present study was to investigate the application of different scenarios for the definition of a drainage fee applied

to hypothetical apartment complexes in the city of Porto Alegre – RS – Brazil. The methodology employed consisted

of analyzing fee values regarding construction enterprises according to the use of the rainwater drainage system. For

such, data were used from a study by Souza et al. (in press), who performed an analysis of hydrographs resulting

from different apartment complexes dimensioned in accordance with hygiene, compensatory and Low Impact

Development (LID) techniques in order to determine which responded better to the desire to maintain natural

hydrological conditions. The cost for solving the current problems of flooding in the city (Cruz, 2004) was averaged

among the apartment complexes according to fee scenarios based on the Total Impermeable Area (TIA), Effective

Impermeable Area (EIA) (Decree n° 15.371/2006, Porto Alegre; Shuster et al., 2005), alteration in volume and in

maximum natural runoff. One of the results of the study was the obtainment of an annual unit cost of R$ 0.49/m² to

finance, operate and maintain a system that would solve the current flooding problems in Porto Alegre. Thus, the fee

to be paid by the three apartment complexes was R$ 21,864.71. The results demonstrate that fee scenarios based

on TIA and EIA (according to Municipal Decree 15.371/2006) fail to encourage the adoption of sustainable

methods for the urban drainage planning. These scenarios resulted in practically equal charges for all the apartment

complexes without assessing alterations in natural runoff characteristics. Charges based on the scenario of alterations

in maximum runoff encourage planning through both the compensatory method as well as LID. Planning lots through

LID provides a lower fee in all scenarios, especially when charge scenarios regard the volume of surface runoff and

EIA (according to Shuster et al., 2005). This result was obtained because the effective production of runoff was

assessed in these scenarios. Thus, the adoption of drainage charges based on the production of surface runoff is the

most adequate alternative to encouraging a reduction in the impact of urbanization on the hydrological cycle in

relation to the assessment criteria of impermeable areas.

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STRATEGIES FOR URBAN DRAINAGE CHARGE IN PORTO ALEGRE – RS – BRAZIL