Geographic Information Systems (GIS) for sustainable water management
At Fraunhofer IGB utilization of Geographic Information Systems (GIS) supports the planning of semi-decentralized water management systems combining the advantages of a small-scale sewage network with the potential for saving and recovering water, nutrients and energy. In particular, sites which are subject to rapid demographic change or which are located in a distinctive geographic position, require innovative solutions.
GIS – important data as planning tool
By the use of GIS data we are able to consider variables such as land use planning aspects, demographic developments, ecological, economic, cultural and social factors when planning plant design for water infrastructure systems. To ease such complex decision-making processes, multi-criteria decision analysis tools in conjunction with geographic information systems are applied to both national and international model regions.
Situation at the model municipality of Saltinho
The site observed, part of the municipality of Saltinho, is located in the Federal State of São Paulo, Brazil. The area under investigation, with approximately 150 inhabitants, is located several kilometers from the main city. Currently, there is no connection to the water supply or sewage. Installing such connections via a sewage system would be very costly. The inhabitants obtain their water from wells located in close proximity to both their houses and the cesspits for household sewage (Fig. 1). Greywater from showers and washing machines is partly discharged directly into the environment without treatment. Hygiene conditions are therefore highly unsatisfactory in some areas.
Approaches towards a solution
A measurement plan requiring area-related data and considering various courses of action as a contribution towards sustainable water management was designed to improve water management: in addition to the installation of a semi-decentralized wastewater treatment system and the utilization of rainwater, the reutilization of treated wastewater is also under consideration.
The requirements for the quality of the treated wastewater and the related technical solutions are determined by the intended use. Social and cultural aspects also need to be taken into consideration. With the help of a survey on the acceptability of various measures by the population it was determined that 30 to 40 % of the inhabitants would welcome measures for sustainable water management.
As the wastewater may still contain substances which may have a long-term negative effect on the quality of the groundwater, despite being treated, the reutilization of wastewater considers such parameters as the distance to surface water or aquifiers. The GIS data illustrated in Fig. 3 demonstrates that vulnerability in the drainage basin around Saltinho is very low so that the agricultural utilization of treated wastewater should, theoretically, not be a problem.
The project is funded by the German Federal Ministry of Education and Research (BMBF) under the promotional reference 02WD0507.
Duration: November 01, 2004 – May 31, 2008, German Academic Exchange Service / Deutscher Akademischer Austauschdienst
UNIMEP FEAU, Santa Barbara d’ Oeste´, Brazil