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Sewer Networks

  • AquaGIS was developed by Aquafin as an overviewing 
          management system for sewer networks
  • Modelling of networks is nowadays a common tool and is
         integrated in Aquafin under the Hydronaut procedure.
  • AquaGIS

    AquaGIS was developed by Aquafin as an overviewing development and management system for sewer networks. It includes a large scale sewer network database model, including a graphic component, which enables all sewer data to be presented visually using all graphical backgrounds, tables, reports and graphs.

    In function of the different users and customer needs, AquaGis attributes a number of components, each defined specifically in function of the needs of the user groups.

    A first component of the software includes data collection and configuration of the sewer database. By using clear import forms, inventoried data is introduced in the database, allowing a visual control and using a graphical background. Validation rules guarantee a high quality of the results using the Aquagis tool. Moreover import & export modules allow data to be transferred smoothly from and into external applications by means of open standards (XML, csv, txt flat files).

    The elaboration of sewer models forms an important 2nd feature of AquaGis. Based on information stored in a sewer database, possible model data such as contributing, paved, roofed areas, inflow hydrograms and Q/ h-curves are added, both graphically and in table form. Hydraulic structures can be described in detail by means of several control-links. Finally AquaGis supports an integrated import & export module to the Infoworks modelling software.

    The third component of AquaGis, creates an environment to introduce mastering data in the model. Using input from camera inspections, field inventories, exports of GIS-datalayers, survey data such as ‘As Is‘ situations, above ground situations, risk areas, … a large scale of different features are integrated in the database. Based on these data, strategic analyses can be made and structural, social and environmental characteristics are accurately assessed.

    By using a central sewer database, besides local sewer databases, it is possible to make the sewer data available to employees in the field, partners and customers by using AquaGis4Web, the web version of AquaGis. In this way, easy access to the most recent data, without need for updating, is accomplished.

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    Hydronaut procedure

    The disadvantages of combined sewers are a well known phenomena, but due to historical and economical reasons, it is almost impossible to rebuild an existing network in a separate sewage and rainfall transport system. This combined system has limitations in transport capacity during exceptional rainfall events, sedimentation problems, uncontrolled flooding as a result of increasing urbanisation, ecological impact of overflows during rainfall events (first flush) causing either pollution of the receiving river or major shock loads to the WWTP.

    Modelling of networks will help the customer in the concept of an appropriate design fulfilling the criteria set in terms of capacity, water velocity, number of overflows and acceptable risk of flooding. Modelling of networks is nowadays a common tool and is integrated in Aquafin under the Hydronaut procedure. It can be summarised in the following steps :

    • Step 1: database
      Consists of the set-up of a database containing the geometrical information of the existing network (levels, diameters, slopes, hydraulic structures, etc.) Therefore we try to make use as much as possible of the existing information available. To check whether the available information is reliable for further use, a 5 % quality check is made: when the test fails, a site survey of the network is necessary in order to elaborate the database.
    • Step 2: configuration of the model
      In this step, the engineer builds up the mathematical model of the network. An important aspect of this stage of the study is to define the level of simplification of the model in comparison with the existing networks. A good simplification is only possible on the basis of a clear understanding of the objectives put forward at the beginning of the study. In our engineering procedures, we have defined five levels of model simplification. The actual practical limitation in modelling generally recommended goes up to 10.000 nodes in one model.
    • Step 3: flow survey & model verification
      Rainfall gauges, flow meters and velocity meters are installed in the network for a duration of six weeks to retrieve the behaviour of the network. The results and the measured rainfall are used as an As Is situation to be compared with predicted flow curves from the theoretical model. This step of the study is very important to verify whether the model behaves with sufficient accuracy.
    • Step 4: design calculation
      Finally the model defines new extensions of the networks by using so-called ‘synthetic’ rainfall events that are statistically representative to the climatic conditions of the country in question. The design is done for several time horizons, allowing the designer to take further developments of urbanisation and growth of population into account in his design.
      The hydronaut procedure enables the client to verify in different summary tables, graphs and final reports the behaviour of the network in the different phases. The procedure describes all different parts and ancillaries of the network and its particular behaviour. The tool is very dynamic and can also be implemented for further upgrading versions of the networks.

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