SUPERVISOR: Günter LANGERGRABER

PROJECT ASSIGNED TO: Elise KARLSSON FAUDOT

Water management has been a cornerstone of societal evolution, influencing agricultural development and the establishment of permanent settlements. Human activity, expanding urban settlements, and growing industrialisation have significantly affected riverine landscapes over time. Large quantities of organic matter and nutrients were discharged into rivers and insufficient handling capacity of sewage systems intensified the degradation of water quality in industrialised rivers. Despite this release of organic matter and nutrients into rivers, there was a long-standing understanding regarding the nutritional value of excreta. Human excreta were historically transported from cities to their surroundings and used as fertilizer, until this was forgotten in the 20th century. In the 1980s, there was a revival of this historical understanding, when substances in wastewater were once more recognised as potential resources.

A more recent trend in water management is the use of Nature-based Solutions (NbS), which shift focus from conventional grey infrastructure. NbS are defined by the COST Action CA17133 Circular City as “concepts that bring nature into cities and those that are derived from nature” (Canet-Martí, et al., 2021). These solutions enhance biodiversity, reduce climate change impacts, and preserve ecosystem services (Seddon, et al., 2020), but are not new concepts. Humans have for long periods of time explored solutions to increase resilience. Nature-based materials have historically been used to manipulate water, where for example, pre-Inca cultures created earthen channels used to divert water. Through this technology, infiltration for recharge of groundwater supplies was possible (McPhillips, et al., 2023). Furthermore, natural wetlands have been used for centuries as sources of wastewater treatment, being convenient "dumping grounds" close to rivers. Around the mid-1900, treatment wetlands (TWs) started being used as engineered systems for wastewater treatment. Designed to operate in more controlled environment than natural wetlands, they use natural processes to remove pollutants (Vymazal, 2022).

This research aims to contribute to a holistic approach regarding the mitigation of impacts organic matter and nutrient flows have on riverine ecosystems. By integrating historical perspectives and modern practices and exploring potential solutions, particularly NbS, the project will investigate how perceptions and management of organic matter and nutrient flows have evolved over the past 300 years along the Danube. The research questions found below will be investigated during the scope of this project:

  1. How did perception on the management of human excreta change over time?
  2. How did modern infrastructure change urban metabolism?
  3. What are leverage points for implementing NbS in a city with existing infrastructure?

References:

Canet-Martí, Alba, et al. "Nature-based solutions for agriculture in circular cities: Challenges, gaps, and opportunities." Water 13.18 (2021): 2565. 

McPhillips, Lauren, et al. "Nature-based solutions as critical urban infrastructure for water resilience." Nature-Based Solutions for Cities. Edward Elgar Publishing, 2023. 147-167.

Seddon, Nathalie, et al. "Understanding the value and limits of nature-based solutions to climate change and other global challenges." Philosophical Transactions of the Royal Society B 375.1794 (2020): 20190120.

Vymazal, Jan. "The historical development of constructed wetlands for wastewater treatment." Land 11.2 (2022): 174.