Making water flows visible, FHNW School of Life Sciences

How can we identify where water is being lost in a city, and how can water suppliers better respond to the consequences of climate change? Answers to these questions are provided by the Water Flow Diagram (WFD1), an analytical approach for the transparent representation of urban water systems. Researchers at the FHNW School of Life Sciences (HLS) are currently using this tool in Peru in collaboration with the German Society for International Cooperation (GIZ). They have adapted it to local conditions to identify weaknesses in the water supply and lay the foundations for a secure long-term drinking water supply.

Patrik Eckert, a researcher in Dr Maryna Peter’s WASH working group at the HLS Institute for Ecopreneurship, collaborated with water supply companies, public authorities and universities in Lima, Tarapoto, Moyobamba and Cusco. The three-week technical mission focused on introducing and validating the water flow diagram. This visualisation tool clearly illustrates water flows in a city and highlights where it is used efficiently and where losses or vulnerabilities occur.

Unlike traditional data tables, the water flow diagram makes complex interactions visible at a glance. It traces the water – from rainfall through rivers and lakes to its use in households, agriculture or industry – whilst also illustrating where it is lost or used unsustainably. This provides water suppliers with a sound basis for planning targeted investments and adapting their infrastructure to future challenges.

A particular focus of the project is on taking regional differences into account. In the Amazon region around Tarapoto the analysis centres primarily on heavy rainfall and its impact on the drinking water supply, whereas in the Andean region around Cusco the focus is on water sources and storage systems. The analyses are supplemented by scenarios for dry and wet seasons, as well as forecasts of population growth, tourism and increasing soil sealing. This enables realistic assessments of future developments.

“The water flow diagram helps to present complex water systems in an understandable way and to make informed decisions for a sustainable water supply” says Eckert.

This collaboration is not limited to practical applications. With the signing of a framework agreement between the HLS and the Universidad Nacional de San Martín (UNSM), the partnership has also been strengthened in the academic sphere. As part of their final-year projects, students at the Peruvian university are further developing the water flow diagram and applying it directly with regional water suppliers.

“The close collaboration between academia and the field creates solutions that can be implemented immediately on the ground whilst also having a long-term impact.”

Following successful trials with the water suppliers EMAPA San Martín, SEDA-CUSCO and EPS Moyobamba, the methodology is set to be incorporated into Peru’s national water management plan. The project is thus making an important contribution to making cities more resilient to the effects of climate change and to securing the long term supply of clean drinking water.

¹ www.waterflowdiagram.ch