SWITCH: Managing Water for the City of the Future

Managing Water for the City of the Future

Rainwater Harvesting

Beijing, China

Confronted with severe water shortages, peri-urban farmers in Beijing are looking to develop multifunctional urban farming systems to deal with the growing problem of lack of water for irrigation. As part of SWITCH, a demonstration project on greenhouse production combined with rainwater harvesting was developed to achieve this aim.

Involving several institutions and a vegetable cooperative in the Huairou district of Beijing, the project has shown that rainwater harvesting technology provides a useful source of water for intensive agriculture under greenhouses and is particularly feasible and profitable if the multiple functions of agriculture are combined. An example of this is the covered rainwater storage pond used in the demonstration. The pond has the dual purpose of storing irrigation water for use in the greenhouses as well as generating humid conditions which are ideal for growing mushrooms thereby providing the farmer with a higher economic return.

The demonstration included rainwater collection from the outer surface of the greenhouses, a rainwater collection flume, a deposit pool, and use of this water by using micro (drip) irrigation. The farm in Huairou depended totally on groundwater, since there was no access to surface water, but this groundwater needed to be pumped from about 40m. Using rainwater reduced the cost of water and increased the total amount of available water. Other innovations demonstrated were: improved production for the Beijing market (grapes, dragon-cactus, mushrooms); agro tourism; groundwater infiltration; and involving the (often new) sectoral institutions (water and agricultural bureaus).

The demonstration project showed positive results providing high quality irrigation water and increasing farmers' income substantially. The higher returns did not only compensate for water fees, but also enabled farmers to pay for the relatively high investment of rainwater harvesting facilities. Local government, which participated in the working group (Huairou District), acknowledged these results and support further application of the developed technology. The results have been integrated into current policies and under the 12th five year plan (2011-2015).

The RWH technology as such is not new. The combined innovations: the technology of combined greenhouses, the storage pool, the improved production, as well as the organisational model (the cooperative) and institutional linkages were. The Beijing Agricultural Bureau has been experimenting with several RWH models, and is now including the one supported by SWITCH. The system developed with the Huairou cooperative is seen as a promising technology.

Belo Horizonte, Brazil

The SWITCH demos on rainwater harvesting in Belo Horizonte were developed with a focus on municipal schools and urban agriculture.

The focus of the first demo was on the use of rainwater for irrigation of gardens, agriculture plots and cleaning of impervious surfaces at the Anne Frank High School. The demo showed a high potential for education on water issues (e.g.: water consumption, saving water, water quality). A local Learning Alliance was established at the school and surrounding neighbourhoods. The project has been intensively discussed with students, teachers, school staff and parents of students. Students are in charge of monitoring the system and reporting back to the school community.

The focus of the second demo was on urban agriculture. A plot was developed in cooperation with the local community and IPES. The technical development of the project was done by UFMG students, the system construction by Belo Horizonte municipality, and operations are done by the local community. Participants were trained on general concepts of urban water sustainability as well as on the techniques for cistern construction. Results showed that rainwater can supply up to 50% of volumes required for irrigation.

In parallel to the demos, a research project on the economics of rainwater harvesting was conducted according to typical water consumption and dwelling characteristics for different socio-economic classes in Belo Horizonte.

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