Sweco’s spatial data-based surface runoff analysis helps municipalities determine their stormwater assets

Sweco helps municipalities and cities determine their stormwater assets with the help of spatial data-based surface runoff analysis. The material compiled by Sweco can be used in predictive maintenance and in the planning and prioritization of precision measurements. The data forms the basis for the asset management of stormwater systems and makes visible the entirety of the municipality’s stormwater assets.

In 2014, the responsibility for managing stormwater in the municipal area was transferred from water utilities to municipalities. With the increase in rainfall caused by climate change and even further urbanization, the sewage network’s leakage water problems and the related overflow risks are increasing.

Sweco created a new service in collaboration with HS-Vesi Oy, a water supply company serving in Hämeenlinna, Akaa and Hattula area, and the city of Hämeenlinna, which helps cities determine their stormwater assets using geospatial data-based surface analysis and visualizes the entire municipality’s stormwater system, from underground stormwater drains to above-ground open drains.

The project manages the overflows of the sewage network by cross-analyzing the above-ground storm water routes with the spatial information about the sewer network. The project is one of the Ministry of the Environment’s projects, which are intended to prevent and reduce sewer overflows and the migration of harmful substances into waterways.

“The water supply company should be proactive in the matter of stormwater, even though the overall responsibility for stormwater does not belong to the water supply company in principle. A functioning stormwater system shows itself to the company as, for example, reduced leakage water from the waste water sewer,” planning manager of HS-Vesi OY Jarno Laine explains.

The entire municipality’s stormwater assets are visible

Quantitative and qualitative management of stormwater is important in the protection of drainage basins, but the boundary conditions of water supply structures must also be taken into account when designing management structures. At worst, stormwater management solutions may even weaken the functionality of regional drainage, increasing the risk of surface runoff diverting into the wastewater network. The material produced by Sweco makes it easier to visualize large entities and shows where stormwater management is the safest in terms of wastewater management. Based on the data, maintenance needs for the terrain can also be defined and maintenance work can be prioritized by area.

“Underground infrastructure, i.e. water supply pipelines, are well known at water utilities. With regard to stormwater, the situation is different in some places. The challenge is that the total route of stormwater to waterways is not known, and mapping stormwater routes on the ground in the entire municipality is a huge task. The spatial data-based surface runoff analysis offered by Sweco is fast and, above all, intuitive a tool as a basis for stormwater asset management,” says Pekka Raukola, Sweco’s water supply and asset management expert.

The data can be used, for example, in the determination of stormwater fees, and it also provides better baseline information for land use planning. The data can be exported to the municipality’s own map system, so that everyone can use the information in their own work.

The customer can process and use the stormwater system independently in the future. In this project, the material produced by Sweco will be integrated into HS-Vesi Oy’s own online information system, so it can be used in project and general planning. The material provides the municipality’s planners with information and a basis for more sustainable land use planning, and on the basis of it, various stakeholders are offered material to support decision-making.

“In the future, HS Vesi Oy operating area will have a 100% view of stormwater flow routes, which is a great achievement in an operating area that includes three municipalities,” says Jarno Laine with satisfaction.