Hydromatic

Tina Nevarez

Prabjit Virdee

Jeremy Delgado

Topic: Water Simulations for Maricopa County

Abstract

Water simulation provided us with the ability to change the future of water in Maricopa County.††† In scenario 1 we changed the policy to a five year sustainable overdraft which dropped agricultural use, and allowed more groundwater to build up.In scenario 2 we chose a pessimistic route which meant that both Salt Verde annual runoff and system storage decreased drastically.

Introduction

WaterSim is a simulation of the water supply in Maricopa County. These simulations vary by climate, storage, use, ground water supply, and annual runoff. In these models we can compare the amounts of water now vs. the future. It also implements different policies about the use of water, types of recycling, and shortages.The WaterSim inputs include the Colorado, Salt and Verde Rivers, water demand based on population and agricultural use, and water shortage policies.†† This simulation can be used by educators who address water issues.Planners can also use this simulation to forecast different scenarios and plan more effectively.

Materials and Methods

The website: watersim.asu.edu allows you to choose many different scenarios in the scenario builder option to compare to the default simulations. This program was developed by Arizona State Universityís Decision Center for a Desert City.

The first scenario builder includes the water shortage policy comparing demand satisfaction and a five year sustainable overdraft.Implementing the policy in year 2010 and the policy being that agriculture loses water first. We are comparing to the default setting which is satisfying demand starting in 2025, with proportional shortage sharing. These decisions can guide us through shortages while minimizing the use of ground water. Policy decisions can guide us through periods of water shortage while minimizing our mining of groundwater. In this section, we choose a water policy, and then adjust relevant inputs for that policy.

The next simulation includes the Salt and Verde Rivers keeping all the factors the same except the climate.The climate change scenario is changed to be the most pessimistic and will change the amount of water available. To simulate the flow of the Salt and Verde Rivers into the future, we extract a portion of their historical flow starting in the year you choose. Next, we can adjust this flow to simulate a drought or excess runoff. For a drought, for example, we'll choose runoff conditions less than 100%. We also choose the year when this drought or excess is to start and how long it is to last. Lastly, we may choose a climate change scenario; the selected scenario's findings are adapted to the Salt and Verde Rivers watershed and may change the amount of water available for the simulation. The default setting begins in 1970, has 100% of normal runoff with duration of ten years.

Results

This graph depicts the amount of water available from various sources based on the simulation.

DEFAULT ††††††††††††††††††††††††††††††††††††† SCENARIO 1

This graph depicts the amount of water calculated to be demanded by various uses,

subject to the availability of water from the sources.

This graph depicts the calculated accumulated change in groundwater since the starting year of the model simulation due to recharging and pumping.

 

DEFAULT††††††††††††††††††††††††††††††††††††††† SCENARIO

This graph depicts the calculated commercial and residential water usage in gallons per person per day after taking into account water supply, water demand, and water policy.

 

 

 

The first graph shows the simulated Salt and Verde River flow, while the second graph shows the simulated amount of water stored in the reservoirs of the Salt and Verde Rivers as a result of the simulated river flow.

 

DEFAULT††††††††††††††††††††††††††††††††††††††† SCENARIO 2

This graph depicts the amount of water available from various sources based on the simulation.

 

Legend for the Maricopa County Water Sources graph

This graph depicts the amount of water calculated to be demanded by various uses, subject to the availability of water from the sources.

 

Legend for the Maricopa County Water Uses graph

DEFAULT††††††††††††††††††††††††††††††††††††††† SCENARIO 2

This graph depicts the calculated accumulated change in groundwater since the starting year of the model simulation due to recharging and pumping.

 

Legend for the Change in Groundwater Supply graph

This graph depicts the calculated commercial and residential water usage in gallons per person per day after taking into account water supply, water demand, and water policy.

 

    Legend for the Gallons per Capita per Day graph

Discussion

 

In the first simulation we can see that the amount of water available from the salt water project drops drastically and then has various ups and downs. The Central Arizona Project and ground water levels drop but then stay constant after the decline. The next chart represents the Maricopaís water uses calculated to be demanded starting 2010 depending on availability recharge and agricultural uses vary a lot but commercial and residential stay constant.The amount of ground water supply growing in the preset simulation to very close to non-existent.†† This is due to the recharging and pumping in this scenario.Gallons per capita per day show very little change until about 2026 where it shows a small decline.

Simulation 2 projects the future flow of the Salt and Verde Rivers. Normal runoff continues to be at 100%, runoff year in now, duration of the simulation being 10 years.The climate scenario has been changed to the most pessimistic option.First we can see annual runoff with the water amount dropping considerably as well as the amount of stored water.The Salt River Project water becomes the water source that is used the least. Central Arizona Project and ground water levels go up.The amount of water used for agriculture, commercial, and residential use seem to be at a steady incline.The ground water is a lot more saved than in the default setting. The amount of water in commercial and residential areas consumed stays the same in this situation.

 

Conclusion

††††††††† The settings we changed in scenario 1 and 2 changed the outcome the water supply as compared to the default setting.In scenario 1- water sources the salt water project, central Arizona project, and groundwater levels dropped. The salt water project varies while the others donít.In scenario 1- Water Uses, more water is recharged, while less water is used for agricultural uses.Commercial and residential uses stay relatively the same as the default option.Scenario 1- ground water increases while gallons per capita per day stay the same with a minor drop in 2025.

Scenario 2 was more pessimistic.The Salt Verde annual runoff was much less in the pessimistic scenario.The Salt Verde system storage also dropped significantly.Water sources shifted from the Salt River project to groundwater, while CAP water remained the same.In the water resources graph a pessimistic scenario resulted in a drop of recharge and agricultural use, while residential use increased.The stress on ground water supply is increased.Gallons per capita per day stay relatively the same.

References

Decision Center for a Desert Cityís Watersim model website:http://watersim.asu.edu/

 

Water Harvesting

 

††††††††† Water harvesting was a project to figure out how much water is needed to water a certain amount of turf area.Our building was the Space Sciences building which had a roof area of 6693 square feet and the turf area was 2250 sq feet.By entering these numbers into the excel spread sheet provided we could see how much the irrigation requirements were. The turf area that would bring the total annual water harvested from the roof into balance with the irrigation water required by the turf area is 1535 sq feet.The estimated volume of the cistern needed at site is 2572 cu feet.It the roof area of building could not provide enough water to irrigate the turf area we could save water in cistern when there is more rainfall or we could also change the size of the turf area so there would be enough water.This spreadsheet converts both the precipitation and ET 0 values from inches to feet so we could see the difference in the requirements.To figure out how big of a cistern you need for your site you add the 3 largest negative amounts in the net harvested water minus the irrigation requirements.We have concluded that the size of the turf area needs to be considerably smaller than the roof area for there to be enough water.