CapÃtulo 35 Cerca de sedimentos - Pliniotomaz.com.br
CapÃtulo 35 Cerca de sedimentos - Pliniotomaz.com.br
CapÃtulo 35 Cerca de sedimentos - Pliniotomaz.com.br
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Manejo <strong>de</strong> águas pluviais<<strong>br</strong> />
Capitulo <strong>35</strong>- <strong>Cerca</strong> <strong>de</strong> <strong>sedimentos</strong><<strong>br</strong> />
Engenheiro Plínio Tomaz 28 <strong>de</strong> agosto <strong>de</strong> 2008 pliniotomaz@uol.<strong>com</strong>.<strong>br</strong><<strong>br</strong> />
Figura <strong>35</strong>.8- Detalhes da cerca <strong>de</strong> <strong>sedimentos</strong> (silte)<<strong>br</strong> />
<strong>35</strong>.9 First flush<<strong>br</strong> />
As pesquisas da EPA, 2004 indicam a concentração do pico <strong>de</strong> <strong>de</strong>pósito <strong>de</strong> <strong>sedimentos</strong> nos<<strong>br</strong> />
primeiros 15min <strong>de</strong> runoff .<<strong>br</strong> />
13.10 Mo<strong>de</strong>lo matemático para cálculo da cerca <strong>de</strong> <strong>sedimentos</strong><<strong>br</strong> />
Conforme EPA, 2004 encontramos os procedimentos <strong>de</strong> cálculo hidrológicos, hidráulicos,<<strong>br</strong> />
transporte <strong>de</strong> <strong>sedimentos</strong> e retenção <strong>de</strong> <strong>sedimentos</strong> e para o qual faremos algumas adaptações.<<strong>br</strong> />
Para a carga <strong>de</strong> <strong>sedimentos</strong> po<strong>de</strong>mos usar o RUSLE que está no Capítulo 05 <strong>de</strong>ste livro e assim<<strong>br</strong> />
resumido:<<strong>br</strong> />
A= R. K. L S. C . P<<strong>br</strong> />
Sendo:<<strong>br</strong> />
A= perda anual <strong>de</strong> solo do solo (ton/ha/ano) <strong>de</strong>vido ao escoamento superficial;<<strong>br</strong> />
R= fator <strong>de</strong> erosivida<strong>de</strong>. No Estado <strong>de</strong> São Paulo R=675 MJ/ha/mm/h<<strong>br</strong> />
K= fator <strong>de</strong> erodibilida<strong>de</strong> que varia <strong>de</strong> 0,03 a 0,79 ton/MJ/ha/(mm/h). Adotado K=0,65 ton/MJ/mm/h<<strong>br</strong> />
erodibilida<strong>de</strong> alta <strong>com</strong> solo nu.<<strong>br</strong> />
LS= fator <strong>de</strong> <strong>de</strong>clivida<strong>de</strong> e <strong>com</strong>primento <strong>de</strong> encosta (adimensional)<<strong>br</strong> />
LS=0,00984 x S 1,18 x Lx 0,63<<strong>br</strong> />
Sendo:<<strong>br</strong> />
S=<strong>de</strong>clivida<strong>de</strong> do terreno (%)<<strong>br</strong> />
Lx= <strong>com</strong>primento que varia <strong>de</strong> 10m a 180m<<strong>br</strong> />
C= fator <strong>de</strong> prática <strong>de</strong> cultura variando <strong>de</strong> 0,001 a 1,0 (adimensional). Adotado C=1 (área <strong>de</strong>snuda)<<strong>br</strong> />
P= fator <strong>de</strong> prática <strong>de</strong> cultura contra erosão que varia <strong>de</strong> 0,3 a 1,0 (adimensional). Normalmente<<strong>br</strong> />
adotado P=1 para áreas urbanas.<<strong>br</strong> />
Exemplo <strong>35</strong>.1<<strong>br</strong> />
Calculo do fator <strong>de</strong> <strong>de</strong>clivida<strong>de</strong> e <strong>com</strong>primento da encosta LS sendo S=8% e Lx=10m<<strong>br</strong> />
LS=0,00984 x S 1,18 x Lx 0,63<<strong>br</strong> />
LS=0,00984 x 8 1,18 x 10 0,63 =0,49<<strong>br</strong> />
Exemplo <strong>35</strong>.2<<strong>br</strong> />
Calcular a perda <strong>de</strong> solo anual dados:<<strong>br</strong> />
C=1<<strong>br</strong> />
P=1<<strong>br</strong> />
LS=0,49<<strong>br</strong> />
K=0,65<<strong>br</strong> />
R=675<<strong>br</strong> />
A= R. K. L S. C . P<<strong>br</strong> />
A= 675x 0,65x0,49x1,00x1,00=215 ton/ha x ano<<strong>br</strong> />
Equação das chuvas intensas<<strong>br</strong> />
Paulo Sampaio Wilken em 1972 obteve para a região Metropolitana <strong>de</strong> São Paulo por análise<<strong>br</strong> />
<strong>de</strong> regressão <strong>com</strong> dados <strong>de</strong> 1934 a 1959 (26 anos) do pluviógrafo instalado no Parque do Estado na<<strong>br</strong> />
Água Funda E3-0<strong>35</strong>, obtendo a seguinte equação das chuvas:<<strong>br</strong> />
Sendo:<<strong>br</strong> />
I= intensida<strong>de</strong> média da chuva (mm/h);<<strong>br</strong> />
T r = período <strong>de</strong> retorno (anos);<<strong>br</strong> />
t=duração da chuva (min).<<strong>br</strong> />
<strong>35</strong>-8
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