The Sample crowdsourcing application is here available.

Sample crowdsourcing application

Project sketch


Frequently following a precipitation event significant problems occur with surplus water cannot flow away instantly. This mainly affects people working in agriculture, but consequences do not stop here. If we consider that roads can periodically become impassable, inundations affects a wide range of people. Experience shows that this problem can be handled efficiently by maintaining and expanding the existing network of ditches (precipitable water discharge, seepage pits etc.). The efficiency of these systems is influenced not only by the existence of such ditches, their current condition is also a crucial factor. Unfortunately there is no consolidated database extending to the spatial location of the various types of ditches, and with regard to their condition even less information is available to the broader public. A possible approach towards solving this problem is to provide the affected people with up-to-date information on the type and volume of pending hazards. Geoinformatical methods can support such a solution.


The aim of the web-based application to be developed is to make use of crowdsourcing involving the affected population itself into the task of data collection in view of a hydrologic analysis. Hydrological analysis means to visualise the areas potentially at risk, depending on different precipitation quantities and various values of influencing factors (such as the depth of ditches). Another goal is for the application to be easily interpreted by everybody.

A basic condition of the analysis is an up-to-date spatial database on the locations, parameters and current condition of ditches. In our view, crowdsourcing as a mean of data collection can provide significant support towards the creation of a database:

  • Free user access to the application
  • An affected user may
    • draw in the position of ditches
    • modify the status of the existing ditch system according to current condition
    • add or modify a value to parameters relevant for the analysis.
  • The result of the analysis drawn from the database created and maintained by the users is available to anyone.


The analysis involves predefined meteorological conditions including the most frequently occurring, realistic types of precipitation in terms of intensity, quantity and length.

By way of this application users receive information on the likely effects of various precipitation events next to the parameters of the given ditch system. Users may also study the potential effects of modifying the parameters of the ditch system (e.g. scooping the ditches) or of extending the system range (e.g. extending or creating ditches). With the help of this information the protection against inundation can be achieved in a more efficient way.


Application architecture (sketch)

The application is realised with open resources.

Client-side operations:

The purpose of the client side is to visualise map data, execute editing of data layers, send requests to the server side, and analyse the responses received, next to executing the corresponding process.

Resources used for the client: OpenLayers, JavaScript, php, HTML. The requests necessary for the analyses are sent via a WPS protocol, and the responses arrive the same way.


Server-side operations:

The purpose of the server side is to supply map data, forward arriving requests to GRASS, carry out analyses, and send responses according to the WPS protocol.

Map data is supplied via: GeoServer

Apache Tomcat servlet engine with 52 North WPS extension + wps-grass-bridge

Modelling software: GRASS 7.0