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Dresti C, Rogora M, Buzzi F, Beghi A, Magni D, Canziani A, Fenocchi A. A modelling approach to evaluate the present and future effectiveness of hypolimnetic withdrawal for the restoration of eutrophic Lake Varese (Northern Italy). JOURNAL OF ENVIRONMENTAL MANAGEMENT 2023; 347:119042. [PMID: 37774663 DOI: 10.1016/j.jenvman.2023.119042] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/21/2023] [Revised: 09/12/2023] [Accepted: 09/17/2023] [Indexed: 10/01/2023]
Abstract
Hypolimnetic withdrawal has been applied as a restoration measure in lakes subject to eutrophication together with external load reduction, to decrease internal load by removing limiting nutrient phosphorus (P) from anoxic deep waters and contributing to the unloading of bottom sediments from previously deposited nutrients and organic matter. The aim of this study is to evaluate the effect of hypolimnetic withdrawal on Lake Varese, a 24 m-deep and 14.8 km2-large subalpine lake in North-Western Italy. The lake suffered from extended eutrophication in the second half of the 20th century due to uncontrolled delivery of untreated urban sewage. Several restoration measures have been implemented during the years, including hypolimnetic withdrawal. In 2019, a cooperative programme for the protection and management of the lake and its surroundings was launched, establishing a systematic annual hypolimnetic withdrawal in the stratified season since 2020. In this research, we calibrated a one-dimensional (1D) coupled ecological-hydrodynamic model (General Lake Model/Aquatic EcoDynamics - GLM/AED2) of Lake Varese with data surveyed in the lake in 2019-2021. Model simulations of the period 2020-2021 with and without the performed withdrawal proved the effectiveness of this measure on hypolimnetic P concentration reduction. Then, future simulations of 2023-2085 were carried out to predict the future efficiency of hypolimnetic withdrawal and of reductions in external nutrient loads under climate change scenarios. Results show that the prescribed withdrawal increases hypolimnetic temperatures. This effect, coupled with thermocline deepening due to global warming, will possibly lead to decreasing water mass stability in autumn and shorter stratification in the moderately deep Lake Varese, with an eventual decrease of P concentrations in the water column. The future effectiveness of hypolimnetic withdrawal is further discussed considering the possible role of dry periods.
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Affiliation(s)
- Claudia Dresti
- National Research Council, Water Research Institute (CNR-IRSA), Largo Tonolli 50, 28922, Verbania, Italy.
| | - Michela Rogora
- National Research Council, Water Research Institute (CNR-IRSA), Largo Tonolli 50, 28922, Verbania, Italy.
| | - Fabio Buzzi
- Agenzia Regionale per La Protezione Dell'Ambiente Della Lombardia (ARPA Lombardia), Via Ippolito Rosellini 17, 20124, Milano, Italy.
| | - Andrea Beghi
- Agenzia Regionale per La Protezione Dell'Ambiente Della Lombardia (ARPA Lombardia), Via Ippolito Rosellini 17, 20124, Milano, Italy.
| | - Daniele Magni
- Direzione Generale Ambiente e Clima, Regione Lombardia, Piazza Città di Lombardia 1, 20124, Milano, Italy.
| | | | - Andrea Fenocchi
- National Research Council, Water Research Institute (CNR-IRSA), Largo Tonolli 50, 28922, Verbania, Italy; Department of Civil Engineering and Architecture, University of Pavia, Via Ferrata 3, 27100, Pavia, Italy.
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Mi C, Shatwell T, Kong X, Rinke K. Cascading climate effects in deep reservoirs: Full assessment of physical and biogeochemical dynamics under ensemble climate projections and ways towards adaptation. AMBIO 2023:10.1007/s13280-023-01950-0. [PMID: 37940832 DOI: 10.1007/s13280-023-01950-0] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/06/2023] [Revised: 08/25/2023] [Accepted: 10/02/2023] [Indexed: 11/10/2023]
Abstract
We coupled twenty-first century climate projections with a well-established water quality model to depict future ecological changes of Rappbode Reservoir, Germany. Our results document a chain of climate-driven effects propagating through the aquatic ecosystem and interfering with drinking water supply: intense climate warming (RCP8.5 scenario) will firstly trigger a strong increase in water temperatures, in turn leading to metalimnetic hypoxia, accelerating sediment nutrient release and finally boosting blooms of the cyanobacterium Planktothrix rubescens. Such adverse water quality developments will be suppressed under RCP2.6 and 6.0 indicating that mitigation of climate change is improving water security. Our results also suggested surface withdrawal can be an effective adaptation strategy to make the reservoir ecosystem more resilient to climate warming. The identified consequences from climate warming and adaptation strategies are relevant to many deep waters in the temperate zone, and the conclusion should provide important guidances for stakeholders to confront potential climate changes.
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Affiliation(s)
- Chenxi Mi
- Department of Lake Research, Helmholtz Centre for Environmental Research, Brückstraße 3A, 39114, Magdeburg, Germany.
- College of Water Conservancy, Shenyang Agricultural University, Shenyang, China.
| | - Tom Shatwell
- Department of Lake Research, Helmholtz Centre for Environmental Research, Brückstraße 3A, 39114, Magdeburg, Germany
| | - Xiangzhen Kong
- Department of Lake Research, Helmholtz Centre for Environmental Research, Brückstraße 3A, 39114, Magdeburg, Germany
- State Key Laboratory of Lake Science and Environment, Nanjing Institute of Geography and Limnology, Chinese Academy of Sciences, Nanjing, China
| | - Karsten Rinke
- Department of Lake Research, Helmholtz Centre for Environmental Research, Brückstraße 3A, 39114, Magdeburg, Germany
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Gong F, Luo L, Li H, Chen L, Zhang R, Wu G, Zhang J, Shi W, Zhang F, Zhang H, Sun T. Quantitative Assessment of Water Quality Improvement by Reducing External Loadings at Lake Erhai, Southwest China. INTERNATIONAL JOURNAL OF ENVIRONMENTAL RESEARCH AND PUBLIC HEALTH 2023; 20:5038. [PMID: 36981948 PMCID: PMC10048958 DOI: 10.3390/ijerph20065038] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 01/31/2023] [Revised: 03/03/2023] [Accepted: 03/06/2023] [Indexed: 06/18/2023]
Abstract
To quantitatively evaluate the effects on water quality improvement caused by reducing external loadings entering Lake Erhai through inflow rivers, a one-dimensional hydrodynamic and ecological model (DYRESM-CAEDYM) was set up to simulate the water quality and water level variations. The calibrated and validated model was used to conduct six scenarios for evaluating the water quality responses to different amounts of external loading reduction at Lake Erhai. The results show (1) the total nitrogen (TN) concentration of Lake Erhai will be higher than 0.5 mg/L without any watershed pollution control during April-November 2025, which cannot meet Grade II standard of the China Surface Water Environmental Quality Standards (GB3838-2002). (2) External loading reductions can significantly reduce the concentrations of nutrients and Chla at Lake Erhai. The effects of water quality improvement will be proportional to the reduction rate of external loading reductions. (3) Internal release might be an important source of pollution It needs to be seriously considered as well as external loading for mitigating the eutrophication at Lake Erhai in the future.
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Affiliation(s)
- Falu Gong
- Institute for Ecological Research and Pollution Control of Plateau Lakes, School of Ecology and Environmental Science, Yunnan University, Kunming 650504, China
| | - Liancong Luo
- Institute for Ecological Research and Pollution Control of Plateau Lakes, School of Ecology and Environmental Science, Yunnan University, Kunming 650504, China
| | - Huiyun Li
- Nanjing Institute of Geography and Limnology, Chinese Academy of Sciences, Nanjing 210008, China
| | - Lan Chen
- Institute for Ecological Research and Pollution Control of Plateau Lakes, School of Ecology and Environmental Science, Yunnan University, Kunming 650504, China
| | - Rufeng Zhang
- Institute for Ecological Research and Pollution Control of Plateau Lakes, School of Ecology and Environmental Science, Yunnan University, Kunming 650504, China
| | - Guizhu Wu
- Institute for Ecological Research and Pollution Control of Plateau Lakes, School of Ecology and Environmental Science, Yunnan University, Kunming 650504, China
| | - Jian Zhang
- Institute for Ecological Research and Pollution Control of Plateau Lakes, School of Ecology and Environmental Science, Yunnan University, Kunming 650504, China
| | - Weiqiang Shi
- Institute for Ecological Research and Pollution Control of Plateau Lakes, School of Ecology and Environmental Science, Yunnan University, Kunming 650504, China
| | - Fan Zhang
- Institute for Ecological Research and Pollution Control of Plateau Lakes, School of Ecology and Environmental Science, Yunnan University, Kunming 650504, China
| | - Hao Zhang
- Institute for Ecological Research and Pollution Control of Plateau Lakes, School of Ecology and Environmental Science, Yunnan University, Kunming 650504, China
| | - Ting Sun
- Institute for Ecological Research and Pollution Control of Plateau Lakes, School of Ecology and Environmental Science, Yunnan University, Kunming 650504, China
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Piccioni F, Casenave C, Baragatti M, Cloez B, Vinçon-Leite B. Calibration of a complex hydro-ecological model through approximate Bayesian computation and random forest combined with sensitivity analysis. ECOL INFORM 2022. [DOI: 10.1016/j.ecoinf.2022.101764] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
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A Three-Dimensional Coupled Hydrodynamic-Ecological Modeling to Assess the Planktonic Biomass in a Subalpine Lake. SUSTAINABILITY 2021. [DOI: 10.3390/su132212377] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
In this study, a coupled three-dimensional hydrodynamic-ecological model was developed to comprehensively understand the interaction between the hydrodynamics and ecological status of a lake. The coupled model was utilized to explore the hydrodynamics, water quality, and ecological status in an ecologically rich subalpine lake (i.e., Tsuei-Feng Lake (TFL), located in north-central Taiwan). The measured data of water depth, water temperature, water quality, and planktonic biomass were gathered to validate the coupled model. The simulated results with a three-dimensional hydrodynamic and water quality-ecological model reasonably reproduced the variations in observed water depth, water temperature, water quality, and phytoplankton and zooplankton biomass. Sensitivity analysis was implemented to determine the most influential parameter affecting the planktonic biomass. The results of sensitivity analysis indicated that the predation rate on phytoplankton (PRP) significantly affects the phytoplankton biomass, while the basal metabolism rate of zooplankton (BMZ) importantly affects the zooplankton biomass. Furthermore, inflow discharge was the most important environmental factor dominating the phytoplankton and zooplankton biomass of TFL. This implies that the runoff in the catchment area caused by rainfall and the heavy rainfall induced by climate change may affect the planktonic biomass of the lake.
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Soares L, Calijuri M. Sensitivity and identifiability analyses of parameters for water quality modeling of subtropical reservoirs. Ecol Modell 2021. [DOI: 10.1016/j.ecolmodel.2021.109720] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/27/2023]
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Detecting Climate Driven Changes in Chlorophyll-a in Deep Subalpine Lakes Using Long Term Satellite Data. WATER 2021. [DOI: 10.3390/w13060866] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
Climate change has increased the temperature and altered the mixing regime of high-value lakes in the subalpine region of Northern Italy. Remote sensing of chlorophyll-a can help provide a time series to allow an assessment of the ecological implications of this. Non-parametric multiplicative regression (NPMR) was used to visualize and understand the changes that have occurred between 2003–2018 in Lakes Garda, Como, Iseo, and Maggiore. In all four deep subalpine lakes, there has been a disruption from a traditional pattern of a significant spring chlorophyll-a peak followed by a clear water phase and summer/autumn peaks. This was replaced after 2010–2012, with lower spring peaks and a tendency for annual maxima to occur in summer. There was a tendency for this switch to be interspersed by a two-year period of low chlorophyll-a. Variables that were significant in NPMR included time, air temperature, total phosphorus, winter temperature, and winter values for the North Atlantic Oscillation. The change from spring to summer chlorophyll-a maxima, relatively sudden in an ecological context, could be interpreted as a regime shift. The cause was probably cascading effects from increased winter temperatures, reduced winter mixing, and altered nutrient dynamics. Future trends will depend on climate change and inter-decadal climate drivers.
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Mi C, Shatwell T, Ma J, Wentzky VC, Boehrer B, Xu Y, Rinke K. The formation of a metalimnetic oxygen minimum exemplifies how ecosystem dynamics shape biogeochemical processes: A modelling study. WATER RESEARCH 2020; 175:115701. [PMID: 32179270 DOI: 10.1016/j.watres.2020.115701] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/10/2019] [Revised: 01/14/2020] [Accepted: 03/06/2020] [Indexed: 06/10/2023]
Abstract
Metalimnetic oxygen minima are observed in many lakes and reservoirs, but the mechanisms behind this phenomena are not well understood. Thus, we simulated the metalimnetic oxygen minimum (MOM) in the Rappbode Reservoir with a well-established two-dimensional water quality model (CE-QUAL-W2) to systematically quantify the chain of events leading to its formation. We used high-resolution measured data to calibrate the model, which accurately reproduced the physical (e.g. water level and water temperature), biogeochemical (e.g. nutrient and oxygen dynamics) and ecological (e.g. algal community dynamics) features of the reservoir, particularly the spatial and temporal extent of the MOM. The results indicated that around 60% of the total oxygen consumption rate in the MOM layer originated from benthic processes whereas the remainder originated from pelagic processes. The occurrence of the cyanobacterium Planktothrix rubescens in the metalimnion delayed and slightly weakened the MOM through photosynthesis, although its decaying biomass ultimately induced the MOM. Our research also confirmed the decisive role of water temperature in the formation of the MOM since the water temperatures, and thus benthic and pelagic oxygen consumption rates, were higher in the metalimnion than in the hypolimnion. Our model is not only providing novel conclusions about the drivers of MOM development and their quantitative contributions, it is also a new tool for understanding and predicting ecological and biogeochemical water quality dynamics.
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Affiliation(s)
- Chenxi Mi
- Helmholtz Centre for Environmental Research, Department of Lake Research, Magdeburg, Germany; College of Water Conservancy, Shenyang Agricultural University, Shenyang, China.
| | - Tom Shatwell
- Helmholtz Centre for Environmental Research, Department of Lake Research, Magdeburg, Germany
| | - Jun Ma
- Hubei Key Laboratory of Ecological Restoration of River-Lakes and Algal Utilization, Hubei University of Technology, Wuhan, China
| | - Valerie Carolin Wentzky
- Helmholtz Centre for Environmental Research, Department of Lake Research, Magdeburg, Germany; State Agency for Agriculture, Environment and Rural Areas Schleswig-Holstein (LLUR), 24220, Flintbek, Germany
| | - Bertram Boehrer
- Helmholtz Centre for Environmental Research, Department of Lake Research, Magdeburg, Germany
| | - Yaqian Xu
- Hubei Key Laboratory of Ecological Restoration of River-Lakes and Algal Utilization, Hubei University of Technology, Wuhan, China
| | - Karsten Rinke
- Helmholtz Centre for Environmental Research, Department of Lake Research, Magdeburg, Germany
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Impact of Urban Stormwater Runoff on Cyanobacteria Dynamics in A Tropical Urban Lake. WATER 2019. [DOI: 10.3390/w11050946] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
Worldwide, eutrophication and cyanobacteria blooms in lakes and reservoirs are a great concern for water resources management. Coupling a catchment hydrological model and a lake model has been a strategy to assess the impact of land use, agricultural practices and climate change on water quality. However, research has mainly focused on large lakes, while urban reservoirs and their catchments, especially in tropical regions, are still poorly studied despite the wide range of ecosystem services they provide. An integrated modelling approach coupling the hydrological model Storm Water Management Model SWMM and the lake ecological model DYRESM-CAEDYM is proposed for Lake Pampulha (Brazil). Scenarios of increased imperviousness of the catchment and of reduction in the load of nutrients and total suspended solids (TSS) in dry weather inflow were simulated. Runoff water quality simulations presented a fair performance for TSS and ammonium (NH4+) while the dynamics of total phosphorus (TP) and nitrate (NO3−) were poorly captured. Phytoplankton dynamics in the lake were simulated with good accuracy (Normalized Mean Absolute Error, NMAE = 0.24 and r = 0.89 in calibration period; NMAE = 0.55 and r = 0.54 in validation period). The general trends of growth, decline and the magnitude of phytoplankton biomass were well represented most of the time. Scenario simulations suggest that TP reduction will decrease cyanobacteria biomass and delay its peaks as a consequence of orthophosphate (PO43−) concentration reduction in the lake surface layers. However, even decreasing TP load into Lake Pampulha by half would not be sufficient to achieve the water quality objective of a maximum concentration of 60 µg chla L−1. Increased imperviousness in the catchment will raise runoff volume, TSS, TP and NO3− loads into Lake Pampulha and promote greater cyanobacteria biomass, mainly in the beginning of the wet season, because of additional nutrient input from catchment runoff. Recovering Lake Pampulha water quality will require the improvement of the sanitation system. The lake water quality improvement will also require more sustainable and nature-based solutions for urban drainage in order to reduce non-point pollution through infiltration and retention of stormwater and to enhance natural processes, such as chemical sorption, biodegradation and phytoremediation. The integrated modelling approach here proposed can be applied for other urban reservoirs taking advantage of existing knowledge on Lake Pampulha.
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