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| ===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) |
| <li>Y<sub>0.05</sub> = Five percent of the average annual yield (L)
| | <br>A = The catchment area ( m<sup>2</sup>) |
| <li>A = The catchment area ( m<sup>2</sup>)</li>
| | <br>C<sub>vol</sub> = The runoff coefficient for the catchment |
| <li>C<sub>vol</sub> = The runoff coefficient for the catchment</li>
| | <br>R<sub>a</sub> = The average annual rainfall depth (mm) |
| <li>R<sub>a</sub> = The average annual rainfall depth (mm)</li>
| | <br>e = The efficiency of the pre-storage filter |
| <li>e = The efficiency of the pre-storage filter</li>
| |
| </ul>
| |
| </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) |
| <li>D<sub>0.05</sub> = Five percent of the average annual demand (L)</li>
| | <br>P<sub>d</sub> = The daily demand per person (L) |
| <li>P<sub>d</sub> = The daily demand per person (L)</li>
| | <br>n = The number of occupants |
| <li>n = The number of occupants</li>
| | <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> |
| </ul>
| |
| 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> | |
| ---- | | ---- |
| <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> |
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| </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> |
| <br> The total storage volume required (V<sub>S</sub>, in L) is calculated as the product of:
| | <strong>V<sub>S</sub> = A × C<sub>vol</sub> × R<sub>d</sub> × e</strong><br> |
| <ul>
| | <br>V<sub>S</sub> = Storage volume required (L) |
| <li>The catchment area (A, in m<sup>2</sup>)</li>
| | <br>A = The catchment area (m<sup>2</sup>) |
| <li>The design storm runoff coefficient for the catchment (C<sub>vol</sub>)</li>
| | <br>C<sub>vol</sub> = The design storm runoff coefficient for the catchment |
| <li>The design storm rainfall depth (R<sub>d</sub>, in mm), and </li>
| | <br>R<sub>d</sub> = The design storm rainfall depth (mm), and |
| <li> the efficiency of the pre-storage filter (e). </li>
| | <br>e = The efficiency of the pre-storage filter. |
| </ul>
| |
| | |
| </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> |
| <br> The total storage required is the sum of V<sub>S</sub> and Y<sub>0.05</sub>. </p>
| | <strong>Total storage = V<sub>S</sub> + Y<sub>0.05</sub></strong> |
| | | </p> |
| | ---- |
| </div> | | </div> |
| <div class="col-md-4"> | | <div class="col-md-4"> |