The calculation of tourist demand per Demand Centre uses the following formula:

TWD | = | BU * (twdb * 30 / 1000) * OR / 100 |

with |
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TWD | = | Tourist Water Demand (m³/month) |

BU | = | number of Bed Units |

twdb | = | Tourist water demand in litre per bed unit per day |

30 | = | factor to convert from day to month |

1000 | = | factor to convert from litre to m³ |

OR | = | Occupancy Rate in % |

100 | = | factor to convert from Percentage to fraction |

In the above formula, the number of bed units, the occupancy rate and the tourist water demand in litre per bed unit will change for future scenarios. While the **occupancy rate** and the **tourist water demand in litre per bed unit** are set manually, for the number of **bed units **the general concept of growthrate and migration is valid again.

Thus, the number of **bed units **is calculated as follows:

Bn | = | Bb * (1 + G / 100)^{N} + S |

with |
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Bn | = | Bed units at the new year |

Bb | = | Bed units at the previous time step |

G | = | yearly Growth rate in % |

100 | = | factor to convert from percentage to fraction |

N | = | N = (2005 - reference year), for the next steps: N= 5 ( 2010, 2015 etc.) |

S | = | sudden increase/decrease of bed units |