The term drainage is referred to a very wide range of phenomena and situations. For example it can describe the runoff degree of storm water or the wastewater produced from a household or irrigation, individually or collectively. Water drainage can be completely different in an urban area from an agricultural area looking at the entire systems being developed in those two areas. We can define water drainage system as the natural or artificial removal of a surface’s water and sub-surface water from an area.
An artificial water drainage system can be divided in:
The natural water drainage systems include reducing as much as possible pavements, gardening in sidewalks and around houses and retention tanks where the water ends up and gets stored for irrigation or other uses.
GIS as it is well known, is a software with plenty opportunities. In this case also, it can be combined efficiently with water drainage mapping in order to visualize the data and take decisions about the study area. So what is the relation between them, we will see it below!
First of all we need to have data on rainfall intensity, duration-frequency relationships, together with adequate data on the urban storm drainage network and catchment characteristics. Moreover, it is necessary to know the amount of houses and people living in the study area in order to count the wastewater production.
GIS platform is extremely useful in this specific field as visualizes streams and flows and helps us understand in depth how the water drainage system works. More specific the studied area include:
Considering all the above, we need to export as many data as we can and this will happen through the creation of a Digital Elevation Model using the GIS software. The steps we have to follow are shown below:
It is worth noting that when a sink is filled, other sinks may appear and then we have to do it again from the begging till all the wrong sinks obliterate. Subsequently, it is very useful to find the sink depth as it is the element which will help us find out if it is error indeed or just a morphological feature. Below are the listed next steps.
At that point the aid of a mathematics program for geographic analysis is important as we need to create another raster file with the minimum elevation of each sink which is going to be used on the GIS platform in further steps.
To conclude Digital Elevation Models from GIS are the most convenient and useful models to represent earth‘s surface as well as hydrology parameters, flows, streams, pipelines, water drainage etc. Having all the necessary data and following the above steps on GIS we can complete a general study on the field of water drainage. Of course every area is different and we cannot follow a standard guide for each case, however the basic steps and tools were presented above. For further information and questions about GIS or water drainage you can call at +49-30-20679116, or visit the site of Umwelt Informationstechnology Zentrum