Time Varying Water Demand
The objective of this simple model is to define water usage patters and apply them to a base demand rate to simulate time-varying demands for a water system. The first step is to review historical data to determine a base demand rate and then estimate pattern multiplyers. Once the pattern multipliers are determined, they can be applied to varying base demand rates for your system model.
Water usage in municipal, irrigation, or industrial water distribution systems is inherently unsteady due to continuously varying demands. In order to model this type of phenomenon dynamically, we must reflect the time changing state of the real system by representing demand fluctuations and incorporating them into our model.
System flows experience changes on a daily, monthly, and annual basis. For purposes of demonstration, this model will consider seasonal changes in water demand. Seasonal changes in demand can usually be traced back to climatic variables such as temperature, precipitation, agricultural practices, and to a lessor degree the changing habits of the water users such as recrational activities.
This model uses a sub-model ("Average_Annual_Demand") to calculate an annual average water demand for historic monthly water usage rates recorded for agricultural, municipal, and industrial uses of a hypothetical system. The average annual demand is used to calculate the demand pattern ("Pattern_mult"), which is a seasonal multiplier. Now this multiplier can be applied to forecasted annual average demand scenarios. The lookup table, "future_dem_t" contains future average usage rates from 2010 thru 2030.
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