Stormwater Management & GIS
Along with urban planning, infrastructure mapping, and change detection technology, geospatial solutions for hydrology are just as vital to city officials as they are to environmental engineers. Especially with the increasing prevalence and severity of climate-related natural disasters, it is crucial to have access to dynamic and accurate stormwater mapping. Unlike other urban planning technologies, such as mapping the location and attributes of buildings and roads, managing a shifting resource like water can be an ongoing challenge, and as such, it requires technology that is up to the task.
Why Do We Need Stormwater Management?
Impervious surfaces such as asphalt, concrete, and metal are dominant in urban and suburban communities, and while these materials make for durable infrastructure, they prevent stormwater from soaking directly into the soil. When a storm occurs in these places, accumulation of rainfall can then distribute debris and pollutants along its path, as well as cause flooding or blockages in drainage channels. City planners and engineers account for this flow in their designs, developing highly intricate drainage systems to allow runoff to flow through designated channels without disrupting a city’s human population or eroding important structures.
The work doesn’t stop there. Specialists are tasked with inspecting these systems in detail, keeping up-to-date records on the status of each pressure point, valve, and pipeline. According to City of Provo (UT) employees, whose story is documented on ESRI’s website, mapping and managing all that data can be a very inefficient process.
Before the implementation of geospatial utility network models, “Provo staff had to manually identify all the pressure zones, watershed areas, and sewer management areas. This process was tedious and time-consuming for the team, as mappers would spend hours manually tracing out the extents of each zone and populating attributes on the corresponding features.”
In small communities, the existing data for valve locations, drainage outlets, and other critical stormwater management infrastructure is often housed in static or even hand-drawn maps. In these cases, not only is this data non-transferable to the GPS technology being used for inspections, but it is not enriched with necessary attribution (i.e., leak status, condition, date and results of the last inspection). It is also very challenging to catch errors, or gaps in the data. Using incomplete and analog data makes for a much more arduous job for inspectors, and a less efficient stormwater management system overall. Automating quality control and quality assurance workflows has the potential to save a lot of time and resources.
Stormwater Analysis and GIS
As a leader in the space, ESRI is prioritizing and even highlighting stormwater management efforts, which have been enhanced and mitigated using a combination of their geospatial technologies. Their network analysis tools, and specifically utility network tools, are built to address not only the digitization of these systems, but also how the resources flow through them. This concept can be applied to electric and gas networks, as well as stormwater, and unique tools exist for each. Trace networks are also commonly used for stormwater management, an evolution of the original geometric network from the days of ArcMap.
The resulting analysis that users can perform is so much more advanced than with static maps; in addition to being able to visualize how each component of the network is connected, users can determine which customers are impacted by a given outage, or in the case of water systems, when a pipe bursts. Especially with an enterprise deployment, where multiple users can collaborate on a system simultaneously, important decisions can be made about which valves need to be shut off, how much water is being directed to a given channel, or where water needs to be redirected to. Combining this knowledge with customer database information, a system can be created to send automated emails to affected customers, notifying them of the outage and what to expect.
The model can even simulate real-world weather events to test how the system will perform during a storm of varying water volume. This feature is extremely helpful in planning for floods; if a city is equipped with predictive capabilities, they can plan for damage before it happens by implementing flood management infrastructure and best practices.
Who Does Stormwater Management Help?
It is also critical for city stormwater systems to adhere to the Municipal Separate Storm Sewer Systems (MS4) permit program, which includes mandated reporting of stormwater management and watershed restoration efforts.
Deploying automated systems for tracking and managing this activity makes adherence to the MS4 permit program much simpler.
Between city officials, engineers, inspectors, permitting agencies, and the citizens and users of the system, there are quite a few stakeholders in the stormwater management ecosystem. In the case of Prince George’s County (MD), developing visualizations and analytics on their stormwater data has been a key component of the county’s relationship with the public. Their story is also told on ESRI’s website.
“Nongovernmental stakeholders, local municipalities within the county, consultants, and other county divisions can also use the System Map app as a resource to view and understand stormwater management information. The Permitting Department can use it to view existing conditions on a site when a permit application is received.
Incorporated cities can use it to understand how many BMPs and county-owned infrastructure items are within their boundaries. Consultants supporting the Stormwater Management Division can use it as a reference for work they will perform.”
Not only do GIS tools for stormwater management revolutionize the inspection and maintenance process, but they also clearly enhance the way all parties interact with the data. Using a combination of network analysis tools and web map applications, decisions can be made quickly in a crisis, and efficient and effective plans can be put in place for the inevitable challenges of tomorrow.