Decision Support for Lake Restoration: A Case Study in Swedish Freshwater Bodies

Abstract

A considerable number of lakes in Sweden have high phosphorus internal loading from the sediments which cause cyanobacterial blooms every summer. Due to potential risks with such blooms for human health, drinking water supply, and ecosystem services, measures need to be taken to control the phosphorus content. Measures to control the phosphorus input from the surrounding land has been in focus. However, the measures have not been sufficient. This is because phosphorus deposited at the bottom of the lakes for many years are finally starting to leak to the water phase when the decomposition of sediments leads to anoxic conditions. In order to determine effective and efficient lake restoration measures, methods for lake restoration decision support by a multi-criteria analysis and the application of a decision analysis are developed. The multi-criteria analysis includes the determination of costs, longevity, and efficacy of six common lake restoration measures to reduce internal phosphorous loads in two lakes selected as a case study. The results show that aluminum treatment combines a highest efficacy with a high-cost efficiency being thus the optimal identified measure. The method involves adding an aluminum solution to the lakes’ sediment, which binds phosphorus, preventing it to be released to the water column. The multi-criteria model is integrated to a decision analytical model. The decision analytical model is used to identify the monetary socio-economic and environmental boundaries for the implementation of the optimal lake restoration measure.

Evaluation of Algal Control Measures in Eutrophic Reservoirs Based on Aquatic Ecosystem Models

“…The management and control of eutrophication and algae in water sources should consider water usage safety and the ecological risks associated with chemical and microbial methods of algae control, which are challenging to manage. In the prevention and control of algae in water sources such as lakes and reservoirs, the focus should be on reducing nutrient sources, particularly internal sources within the reservoir, and implementing biological and physical algae control measures, such as ecological fish stocking, mollusk breeding, and algae removal equipment [51][52][53][54][55].…”

Sustainable lake restoration: From challenges to solutions

“…In some urban lakes, however, in‐lake chemical treatments were determined to be more cost effective than catchment measures as the costs for reducing external loads sufficiently to improve water quality would be extreme (Huser, Futter, et al, 2016). In a recent study, aluminum treatment was identified as an optimal approach to reduce the internal P load in two Swedish lakes because this treatment combined the highest internal load reduction efficacy with the lowest cost (Sellergren et al, 2023). For Spring Lake (USA) however, Steinman (2019) concluded that, while alum reapplication may be the most cost‐effective solution for aesthetics, it does not lead to ecosystem restoration in a holistic sense because the method creates a vicious cycle of enrichment and treatment and releases potential polluters from responsibility.…”

Urban Water-Related Problems

“…The paper "Decision Support for Lake Restoration: A Case Study in Swedish Freshwater Bodies" [7] presents techniques aimed at providing decision support for lake restoration through a combination of multi-criteria analysis and decision analysis. The main objective is to identify effective and efficient measures for restoring lakes.…”

“…On the other hand, among nine research articles, five articles are related to water quality problems, of which two articles investigate groundwater pollution in Japan and Sweden [5,6], one article deals with lake contamination by phosphorus in Sweden [7], another targets lakes or reservoirs from the perspective of the hydrodynamic response by wind [8], and the last one considers the water pollution problem for a riverbank area in Bangladesh [9]. Three research articles out of the nine are related to problems of urban flood phenomena, in which studies on urban flooding area characteristics in Japan [10], water level forecasting caused by urban floods in Japan [11], and barriers to IFRM (Integrated Flood Risk Management) adaptation in the Philippines [12] are carried out.…”