Towards Smart Water Management through water tax restructuring

Insell is working with the smart concept of including stormwater in the water tax by using GIS and Photogrammetry technologies. The development of an app to streamline this process for citizens is the innovative approach of the company.


The management of water resource is an essential key to city planning as it is an indispensable component of human life. Nowadays, public authorities, municipalities in collaboration with the public and private companies, understand that the management of this precious resource through technologies and smart tools is fundamental in order to guarantee the durability and quality of water resource.

Nowadays, water tax is based on how many cubic meters of water a household uses. Generally, water tax is based only on water consumption intake shown in water meter and does not include rainwater going to drain pipes. At the same time, a substantial quantity of stormwater is drained via sewer systems and go through the same drain pipes where untreated household water is flowing. Regarding this context, InSell´s innovative project aims to propose a new logical basis by including stormwater in the water tax. This restructuring is based on the amount of water calculated for each property type and in order to develop it, the role of geospatial technology is crucial.


Stages of the Project

Stage 1: Conceptual basis to restructure water tax
The quantity of stormwater flowing on impervious areas and drained via drain pipes is much more significant than untreated water used by households. In urban areas, stormwater consists of water from rain which falls on streets, paved roads, parking lots, building’s rooftops and other developed surfaces but its drainage, through sewer systems, is not included in the water tax.

This non-consideration of stormwater in the water tax brings a disproportion about the price between the different types of built-up areas such as single-family houses, multi-stages houses, and commercial buildings. For instance, as shown in figure 1, commercial buildings have large impervious areas as the amount of rainwater precipitation drained is much more significant than a single-family house which has in their properties less sealed area. Taking this as an example, and regarding the amount of water drained on commercial buildings, we can conclude that they do not contribute as much as they should for stormwater drainage as the existing water tax is based only on freshwater consumption and they have a very limited water usage. The main purpose of this new calculation is to rebalance the price of water tax for each property regarding their impervious surfaces per square meter.

Figure 1: Representation of the different types of built-up areas

In order to calculate the amount of water running off on each property, an evaluation and demarcation of sealed areas according to the size and type of the property is required as showed in figure 2. Demarcated impervious surfaces are measured and calculated with the help of GIS and photogrammetry systems as is gonna be explained on stage 2. After this stage is completed, an intensive analyses of the data is conducted to provide a new logical basis for water tax for each property type and household.

Figure 2: Demarcation of the impervious areas

Stage 2: Use of photogrammetry and GIS to provide a logical basis
The key to developing this system is having one go-to repository for all spatial (geographic) and nonspatial (household and partly census) data. The spatial perspective and spatial analysis that GIS systems offer is essential to collect, manage, analyze and distribute information. According to this perspective, geospatial data combine with advanced mapping technologies such as digital photogrammetry and orthophoto image, is efficiently used for the development of the household level maps with heights up to an accuracy of 7-10 cm.
Figure 3 highlights InSell´s data processing workflow and methodology used to compile sealed areas in Photogrammetry systems.

Figure 3: Process workflow

Stage 3: Preparing a Proposal for the citizens to calculate their own water usage
There are many bottlenecks and challenges in the conceptualization and calculation of a new water tax. Citizens are often asked to verify the compiled information about accuracy and correctness. Sometimes, they do not agree with the areas calculated by systems and and have their own measurements of sealed areas of their own property (fill up different information => types of buildings, the material used, size, characteristic of the buildings) what could come into conflict with the concerned authorities. InSell along with its partners is also developing a smarter solution to streamline this process for citizens. This solution will include geospatial web platform and client applications where citizens can fill up the required information using devices (PC, phones, laptop). This app will have functionalities to even check the tax and water consumption according to the type of building and family size and a provision to add new areas or remove existing sealed areas from the property. This will have several advantages for citizens as well as for municipalities in order to exchange information. The concept note of this smarter water app will be presented in a separate blog post on smarter water management.


Benefits of water taxing restructuring

But what are the benefits of restructuring water tax for citizens? By including stormwater in the water tax, allows making the fee more equitable for households as the new fee is related to impervious areas surfaces. It also attends to indirectly incentivize good practices among citizen to minimize the amount of rainwater going to drain by developing green infrastructures on their properties (harvesting water, green roofs). Furthermore, restructuring water tax benefits rainwater management as well and allows to maintain, repair and replace the infrastructures.


InSell´s Role

InSell is adding value and participating in this solution by creating a database and more specific developing the innovative idea of the app development that alters on is going to be more specified. Lots of projects had already been carried such as for the city of Schnwäbisch Gmünd in BW Germany.

The service portfolio of the company for smart water tax restructuring includes services such as:

  • External Orientation
  • Digital Terrain Model (DTM)
  • 2D and 3D Mapping
  • 3D Modelling
  • Ortho Mosaic
  • Airborne Laser Terrain Mapping (ALTM)
  • Mobile LIDAR Scanner Services
  • Terrestrial and UAV LIDAR

By providing those services, InSell intends to provide means for smart solutions and contribute to a sustainable future having in mind the importance of the water resource.


Towards Smart Water Management through water tax restructuring

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