The Gilbert-Chandler Area Drainage Master Study/Plan (ADMS/P) will be updated based on multiple sources of data, but the simplest way to break it down is two-fold:

1. Hydrology and Hydraulic Modeling
2. Storm Event Documentation

The project team collects data from multiple sources, primarily agencies, including the Town of Gilbert, the cities of Chandler and Mesa, and the Gila River Indian Community. The project team has collected the most recent data on:

• Topography and Land Use: Construction and development in the study area can affect how and where stormwater flows and soaks into the ground. For example, stormwater runoff flows down a paved street faster and is more concentrated than in an agricultural field. The street will also soak up less water than the field.
• Soils: The most recent soil data provides information about how the ground will soak up water. Sandy soil, for example, soaks up water faster than hard clay soil.
• Rainfall: Rainfall data has changed since the last studies were prepared for this area. The G-C ADMS/P Update will use the latest rainfall data.
• Infrastructure: As new stormwater infrastructure, such as culverts or storm drain systems that drain into channels or retention basins, is constructed, regional flood hazards and flow patterns change. New drainage infrastructure is being analyzed for the G-C ADMS/P Update.

The data collected will be combined into a model to develop the latest depiction of flood hazards in the study area. Updates in modeling software enable the project team to develop a single model with greater details than software available in past studies.

The study team also needs to collect data about storm events, past or present, from residents and businesses in the study area. This data helps to validate and verify the modeling results. Documentation that shows the location and depth of flooding at a location allows the project team to review the model results against observed evidence to verify that the results show similar patterns. If they do not, the team can verify if something has changed that affects the water flow patterns and adjust the modeling as needed.

Here are some helpful tips on documenting flooding events!

How Can You Help?

If you cannot safely take a photo or video, you can still document the flooding event by providing input on the study’s website. Add a marker on our interactive mapping activity to share specific locations where flooding has occurred OR tell us where you feel there is a concern for future flooding.

Even a comment noting the date, general location, and approximate depth of the flooding is useful.

Submit your photos, videos, or comments directly on the Give Input page.

Want to Learn More? The study team is available to present to your community, contact us to schedule a presentation.