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<li>Y<sub>0.05</sub> = Five percent of the average annual yield (L) <li>A = The catchment area ( m<sup>2</sup>)</li> <li>C<sub>vol</sub> = The runoff coefficient for the catchment</li> <li>R<sub>a</sub> = The average annual rainfall depth (mm)</li> <li>e = The efficiency of the pre-storage filter</li> </ul> <li>D<sub>0.05</sub> = Five percent of the average annual demand (L)</li> <li>P<sub>d</sub> = The daily demand per person (L)</li> <li>n = The number of occupants</li> </ul>Line 28:
Line 24: <br> The total storage volume required (V<sub>S</sub>, in L) is calculated as the product of: <ul> <li>The catchment area (A, in m<sup>2</sup>)</li> <li>The design storm runoff coefficient for the catchment (C<sub>vol</sub>)</li> <li>The design storm rainfall depth (R<sub>d</sub>, in mm), and </li> <li> the efficiency of the pre-storage filter (e). </li> </ul> <br> The total storage required is the sum of V<sub>S</sub> and Y<sub>0.05</sub>. </p>
Rainwater harvesting: Sizing and modeling (view source)
Revision as of 19:22, 11 July 2017
, 7 years ago→Rapid
===Rapid===
===Rapid===
<p>Five percent of the average annual yield can be calculated using the following equation:<br>
<p>Five percent of the average annual yield can be estimated:<br>
<strong>Y<sub>0.05</sub>= A × C<sub>vol</sub> × R<sub>a</sub> × e × 0.05</strong>
<strong>Y<sub>0.05</sub>= A × C<sub>vol</sub> × R<sub>a</sub> × e × 0.05</strong>
<ul>
<br>Y<sub>0.05</sub> = Five percent of the average annual yield (L)
<br>A = The catchment area ( m<sup>2</sup>)
<br>C<sub>vol</sub> = The runoff coefficient for the catchment
<br>R<sub>a</sub> = The average annual rainfall depth (mm)
<br>e = The efficiency of the pre-storage filter
</p>
</p>
<p>Five percent of the average annual demand (D<sub>0.05</sub>) is calculated as the product of:<br>
<p>Five percent of the average annual demand (D<sub>0.05</sub>) can be estimated:<br>
<strong>D<sub>0.05</sub> = P<sub>d</sub> × n × 18.25</strong>
<strong>D<sub>0.05</sub> = P<sub>d</sub> × n × 18.25</strong>
<ul>
<br>D<sub>0.05</sub> = Five percent of the average annual demand (L)
<br>P<sub>d</sub> = The daily demand per person (L)
<br>n = The number of occupants
<br>Good catchment selection means that the runoff coefficient (C<sub>vol</sub>) should be 0.9 or greater. Filter efficiency (e) can be reasonably estimated as 0.9 pending manufacturer’s information.</p>
Good catchment selection means that the runoff coefficient (C<sub>vol</sub>) should be 0.9 or greater. Filter efficiency can be reasonably estimated as 0.9 pending manufacturer’s information.</p>
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<p>The following calculation is based upon two criteria:
<p>Then the following calculations are based upon two criteria:
<ol>
<ol>
<li>A design rainfall depth is to be captured entirely by the RWH system.</li>
<li>A design rainfall depth is to be captured entirely by the RWH system.</li>
</ol>
</ol>
</p>
</p>
<p><strong>When Y<sub>0.05</sub>/ D<sub>0.05</sub> <0.33</strong>
<p>When Y<sub>0.05</sub>/ D<sub>0.05</sub> < 0.33, the storage volume required (V<sub>S</sub>, in L) can be estimated:<br>
<strong>V<sub>S</sub> = A × C<sub>vol</sub> × R<sub>d</sub> × e</strong><br>
<br>V<sub>S</sub> = Storage volume required (L)
<br>A = The catchment area (m<sup>2</sup>)
<br>C<sub>vol</sub> = The design storm runoff coefficient for the catchment
<br>R<sub>d</sub> = The design storm rainfall depth (mm), and
<br>e = The efficiency of the pre-storage filter.
</p>
</p>
<p><strong>When 0.33 < Y<sub>0.05</sub>/ D<sub>0.05</sub> <0.7</strong>
<p>When 0.33 < Y<sub>0.05</sub>/ D<sub>0.05</sub> < 0.7, the total storage required can be estimated by adding Y<sub>0.05</sub>: <br>
<strong>Total storage = V<sub>S</sub> + Y<sub>0.05</sub></strong>
</p>
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