Rainwater Harvesting at the NAU ARD Building


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The ARD Team

Porject Description

Design Process

Site Location

Precipitation Analysis

Water Consumption

Rooftop Analysis

Sizing and Location

Water Distribution

Applicable Regulations

Plans

References

Water Distribution

Background

The reason for the construction and use of a rainwater harvesting system is to the water resources that we have in Northern Arizona.  In many cases, however, overwatering in gardens can be overlooked.  Traditional systems such as flood irrigation, and sprinkler systems can be inefficient and waste water.  For this purpose we have focused on low pressure drip irrigation systems.

Low Pressure Systems

The advantage of using a drip irrigation system for the urban garden as opposed to other methods is that they are highly efficient, and they require low pressure.  Drip irrigation systems are more than 90% efficient in comparison to sprinkler systems that are 50% - 70% efficient. 

Discharge

The discharge at the outlet of the pipeline was determined by using the Energy Equation, and then the headlosses for the system were computed to verify that the water has sufficient flow rate from the tank to the gardening area. The discharge and velocity at different elevation head, z1, are shown below in Table 3 and Figure 8 and 9.

Table 3 Discharge and velocity rate

z1 (ft)

velocity (ft/s)

friction headloss(ft)

Minor headlosses (ft)

Discharge (cfs)

14.50

5.598

13.089

1.411

0.031

8.00

4.158

7.221

0.779

0.023

2.00

2.079

1.805

0.195

0.011

1.00

1.470

0.903

0.097

0.008


Figure 8 Elevation head vs. Discharge


Figure 9 Elevation head vs. Velocity