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To improve the water quality and alleviate the eutrophication of Lake Yangchenghu, the third largest freshwater body within the Lake Taihu basin in China and an important source of drinking water, nutrient reduction strategies should be urgently addressed by decision makers, since virtually no improvement of water quality has taken place since the...
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... results of the calibrated seasonal simulation in the state variables are presented in Figures 3-6. The simulations agreed acceptably with the observations, where all of the h values were less than 1 (Table 3). The AR d values were all less than 45% except for TP, indicating a relatively poor calibration for the total phosphorus (Table 3, Figure 4). ...
Citations
... Globally, large-scale water transfers are widely implemented to conserve the quality and quantity of freshwater (Wang et al., 2018;Bargu et al., 2019;Lee et al., 2020;Zhao et al., 2020;Zhou et al., 2020;F. Peng et al., 2021;H. ...
... Many studies have demonstrated the positive effects of water transfer on receiving water systems, such as increasing water exchange and reoxygenation rate, supplementing water resources, and improving water quality (L. Hu et al., 2010;Gao et al., 2015;Wang et al., 2018), while some researches showed that although water transfer could dramatically facilitate water exchange in most lake regions, its influence on receiving water quality is variable (Feng et al., 2017;Tang et al., 2021). In addition, the increase of external nutrient loads during the water transfer period may cause water quality deterioration in some areas of the receiving lake (Jin et al., 2015;Qin et al., 2019;Chen et al., 2020;Zhang and Wu, 2020;Y. ...
... EcoLake is a vertically-compressed, 3-D hydrodynamic-ecological model, which uses ecological functions to predict the changes in ecosystem structure (Hu et al., 2006(Hu et al., , 2011. EcoLake model has been successfully applied in assessing the impacts of Yangtze River water transfer on the restoration of Lake Chaohu, Lake Taihu and Lake Yangchenghu (Hu et al., 2008;Wang et al., 2018;Z. Peng et al., 2021a), and forecasting the short-term of algal bloom in Lake Taihu and Lake Chaohu (H. ...
Study region: Lake Chaohu is a typically large shallow freshwater lake in China,
experiencing long-term eutrophication and a short period of drought.
Study focus: This study employs a three-dimensional (3-D) hydrodynamic-ecological
model to assess the impacts of water transfer on lake flow, water quality, and their
relationship, and then reveals optimal strategies for achieving improved water quality in
Lake Chaohu.
New hydrological insights for the region: Results indicated that clean water transfer
could dramatically increase flow rate and decrease nutrient concentrations near the
water transfer inlets, while the grade level of lake water quality is not changed. The
degree of improvement in water quality parameters is not always proportional to lake
flow rate. A clean water transfer through the eastern route (ZH) has the largest
improvement effect on the average flow rate and water quality (total nitrogen (TN) and
total phosphorus (TP)) of the entire lake. Winter water transfer improves TN and TP
better than summer, while the opposite for ammonia nitrogen (NH3-N). Decrease of
wind speed is essential for mitigating nutrient accumulation in western lake’s heavily
polluted bay through weakening the reverse circulation and the northwest flow. Water
transfer operations are revealed to improve water quality in Lake Chaohu: conduct
water transfer through ZH in winter, strictly control NH3-N concentration in the donating
water, and combine the effects of the low east wind.
... Excessive P inputs from exogenous loads are casually linked with lake eutrophication phenomenon, such as excessive algal growth and poor water clarity (Scavia et al., 2014;Schindler et al., 2012). Thus, the main focus of lake restoration projects is usually to control external sources of nutrient loading (Jeppesen et al., 2007;Wang et al., 2018). However, when external P loads are reduced in shallow lakes, internal P release can be a key factor contributing to hysteresis in ecosystem response, and thus may interfere with lake restoration effects (Schindler et al., 2012;Søndergaard et al., 2013). ...
... The third is a material transform and transport module, including dissolved oxygen (DO), nitrogen, and phosphorus transport. A detailed description of this model and its applications can be found in Wang et al. (2018). In particular, the simplification of the sediment module into one integrated sediment layer loses the capability to resolve the vertical profiles of P in the sediment (Hu et al., 2006). ...
... , were used to evaluate model performance. The calculation method can be found in Wang et al. (2018). The results are considered as acceptable if 0 ≤ h ≤ 1, and AR d is less than 35%. ...
Sediment phosphorus (P) biogeochemical processes impact water quality. Restoration measures and global warming lead to the same outcome, namely that reactive P moves from the sediments to the bottom waters. In this study, a vertical-compressed sediment P transport model was developed and coupled with a three dimensional (3-D) hydrodynamic-ecological model (EcoLake). The proposed model was used to evaluate the effects of two different strategies (external loads reduction and global warming) on sediment P release flux and P concentrations in the water column of Lake Chaohu, the fifth largest shallow lake in China. The results found that the coupled model accurately reflected P transport in the water column, sediment, and dissolved reactive P (SRP) diffusion at the sediment and water interface. The degradable rate of rapidly degradable organic P (v p1) and adsorbed rate (k ad) are the most sensitive parameters influencing sediment P release flux. The internal SRP loads caused by diffusion accounted for roughly 5% of the total external P loads, with higher values in heavily polluted lake basins (western and eastern) and during warmer seasons (summer and autumn). Sediment P release may have caused the current lake water SRP concentrations to increase by 31.1, 12.0, and 21.2%, in western, central, and eastern basins, respectively, due to the large difference of sediment SRP concentration between three basins. The SRP concentration in water responded to changing loads and water temperature strategies more in the western basin than in the other two basins. The sediment P release flux showed spatially contrary responses between two strategies. These findings have important implications with respect to the effects of sediment P release on water quality, and will assist water quality managers in developing appropriate P control measures.
... However, studies that aim to assess the response of lakes to climate change or changes in tributary nutrient load commonly simulate longer periods of time [19][20][21][22][23]. There are also examples of models that are applied with the aim of evaluating the effectiveness of different restoration measures, including the nutrient load reduction [24][25][26], sediment removal [27], or hypolimetic aeration [28][29][30][31]. The modeling process is often hampered not only because the observed abiotic variables are measured with a significant level of uncertainty [32] but mainly because the sampling frequency of water body inflow quantity and quality is not suitable for the characterization of these variables. ...
Water quality modeling can be an important tool for lake management. However, if the simulation period is small and the forcing data is limited, the result uncertainty may diminish its usefulness. This study was conceived with the aim of implementing a long-term water quality simulation of a shallow eutrophic lagoon, with limited forcing data, to evaluate result uncertainty and the advantages of such an approach for the water management process. The lagoon water quality was simulated, over a period of 19 years (2000 to 2019), with the CE-QUAL-W2 model, and the watershed with the SWAT model. Two different scenarios regarding the lagoon inflow water quality characterization were considered and evaluated. The CE-QUAL-W2 model was used to simulate the lagoon water column and sediment biogeochemical fluxes using the following seventeen constituents as a calibration reference: water temperature; dissolved oxygen; orthophosphates; total phosphorus; ammonia; nitrate plus nitrite; total nitrogen; carbonaceous biochemical oxygen demand; total dissolved solids; pH; six algae biomass groups, and chlorophyll-a. The results show that despite the high level of uncertainty in the lagoon’s daily constituents’ variation, the long-term perspective on the biogeochemical fluxes, as described by the interannual constituent’s evolution, enabled the identification of ecological thresholds, the convergence and divergence of the system, and constituent trajectories. These results can represent a step forward into the establishment of cause-and-effect relationships between pressures and water body status, thus allowing an effectiveness improvement on the integrated water resource planning and management under the European Water Framework Directive.
... Tavabe & Samadi Kuchaksaraei, 2021). One of the most important issues in water transfer between two water sources, is the trophic and physicochemical effects of source ecosystem water on the target ecosystem (Wang et al., 2018). Regarding the transfer of water from Nargesi dam to Parishan wetland, despite the fact that this water transfer is inside a basin and is located between two sub-basins of Helleh water basin, but due to the ecosystem conditions of Parishan wetland and its international importance, medium and long-term physico-chemical effects of this transfer will be analyzed in more detail. ...
... Increasing nutrients, increases the abundance of plants, including macrophytes and planktons. As more plants become available as food sources, there is an increase in the number of herbivores as well as carnivores that feed on them (Ansari et al., 2010;Wang et al., 2018). As the process continues, aquatic biomass will increase, but the biodiversity will decrease. ...
Parishan International Wetland in Fars Province, Iran, has been dried up since 2009. The restoration plan is underway by transferring water from Nargesi dam. The aim of this study was to investigate the physicochemical effects of water transfer from and the possibility of eutrophication in Parishan Wetland. Sampling was done from the active springs and Shirinrood river (behind Nargesi dam). Physicochemical parameters were measured and compared with wet years of the wetland. The average EC of Nargesi Dam and the average EC of wetland water after water transfer, were calculated with an annual input of 15 million m ³ . The results showed, with the entry of water from Nargesi dam in rainy months, after 7–10 years of EC, salinity, hardness and TDS of the wetland will reach the long-term period of the wetland in wet times. After this period, if water input from the dam continues, the water of the wetland will be saltier at the rate of 0.25–0.27 g/l per year, and after 10 years, the salinity will be 2.5–2.7 g/l, which does not create ecosystem contradictions and due to the euryhaline nature of Parishan wetland aquatic animals, it will not have negative ecological effects on the inhabitants. Despite the concentration of nitrate and phosphate in the two water sources, due to the high pH and alkalinity of the wetland water, as it was in the wet years, these two nutrients are not limiting factors for production, but due to the high pH and high alkalinity, eutrophication will not occur.
... In this context, it is important to note that these classes are mainly based on biological metrics, among which the phytoplankton (Laplace-Treyture and Feret, 2016; Le Vu et al., 2011;Phillips et al., 2013). Consequently, forecast models could help lake restoration objectives by testing scenarios with some key issues, such as eutrophication and climate change (Lehmann and Hamilton, 2018;Wang et al., 2018). Such models could also help in forecasting the HAB events and avoid financial losses by creating a decision support tool, to determine the fishing periods in lakes (Gill et al., 2018;Manning et al., 2019). ...
The development of anthropic activities during the 20th century increased the nutrient fluxes in freshwater ecosystems, leading to the eutrophication phenomenon that most often promotes harmful algal blooms (HABs). Recent years have witnessed the regular and massive development of some filamentous algae or cyanobacteria in Lake Geneva. Consequently, important blooms could result in detrimental impacts on economic issues and human health. In this study, we tried to lay the foundation of an HAB forecast model to help scientists and local stakeholders with the present and future management of this peri-alpine lake. Our forecast strategy was based on pairing two machine learning models with a long-term database built over the past 34 years. We created HAB groups via a K-means model. Then, we introduced different lag times in the input of a random forest (RF) model, using a sliding window. Finally, we used a high-frequency dataset to compare the natural mechanisms with numerical interaction using individual conditional expectation plots.
We demonstrate that some HAB events can be forecasted over a year scale. The information contained in the concentration data of the cyanobacteria was synthesized in the form of four intensity groups that directly depend on the P. rubescens concentration. The categorical transformation of these data allowed us to obtain a forecast with correlation coefficients that stayed above a threshold of 0.5 until one year for the counting cells and two years for the biovolume data. Moreover, we found that the RF model predicted the best P. rubescens abundance for water temperatures around 14°C. This result is consistent with the biological processes of the toxic cyanobacterium. In this study, we found that the coupling between K-means and RF models could help in forecasting the development of the bloom-forming P. rubescens in Lake Geneva. This methodology could create a numerical decision support tool, which should be a significant advantage for lake managers.
... In order to take precaution for eutrophication, one of the effective ways is to conduct water quality assessment of freshwater ecosystems (de Oliveira et al. 2020;Jiang et al. 2019). Water quality assessment aims to understand the current trophic status of a freshwater ecosystem, which may help to predict the altering of water quality in an ever-changing water environment (Plew et al. 2018;Wang et al. 2018b). In this way, appropriate mitigation strategies might be adopted to prevent eutrophication as well as its possible consequences (e.g., harmful algal blooms). ...
Water quality evaluation of freshwater ecosystems has been widely reported based on the physical and chemical parameters of water (e.g., Carlson’s trophic state index (TSI)), while the aquatic microorganisms are actually a more intuitive way to reflect the eutrophic levels. This article was based on 27 global freshwater ecosystems including freshwater rivers, lakes, and reservoirs. Bacterial eutrophic index (BEI) was determined as the function of temperature and abundances of Cyanobacteria and Actinobacteria. BEI and TSI values of the freshwater ecosystems were determined and the correlation analysis of TSI and BEI indicated their positive correlation (ρ = 0.452, p < 0.01). Furthermore, an eutrophication classification based on BEI was proposed. It turned out that BEI was a possible feasible method for water quality evaluation. The aquatic microorganism-based method such as BEI should be considered for water quality evaluation of a freshwater ecosystem. Complicated models combined with physicochemical (e.g., TSI) and microbial (e.g., BEI) method are recommended for water quality evaluation of a freshwater ecosystem in future.
... In Lake Yangcheng, there are many inflowing and outflowing rivers ( Figure 1). According to multi-year observations, the inflowing water is generally from north to south and from west to east; its retention time is 0.38 year [38]. ...
... In Lake Yangcheng, there are many inflowing and outflowing rivers ( Figure 1). According to multi-year observations, the inflowing water is generally from north to south and from west to east; its retention time is 0.38 year [38]. Lake Yangcheng is a representative lake with pen aquaculture of CMC in China. ...
... Generally, excess nitrogen (N) and phosphorus (P) loading from the point and non-point sources in a watershed are considered as one of the main factors damaging the ecological quality of lakes [38,40,55]. In Lake Yangcheng, besides the external nutrient loadings such as industrial effluents and agriculture non-point sources, intensification through increasing use of pelleted feeds and the expansion of pen aquaculture area was another main factor inducing lake eutrophication and deteriorating of WQ [2]. ...
Pen aquaculture is the main form of aquaculture in some shallow lakes in eastern China. It is valuable to map the spatiotemporal changes of pen aquaculture in eutrophic lakes to assess its effect on water quality, thereby helping the relevant decision-making agencies to manage the water quality (WQ) of lakes. In this study, an automatic approach for extracting the pen aquaculture area was developed based on Landsat data. The approach integrates five algorithms, including grey transformation, discrete wavelet transform, fast Fourier transform, singular value decomposition and k-nearest neighbor classification. It was successfully applied in the automatic mapping of the pen aquaculture areas in Lake Yangcheng from 1990 to 2016. The overall accuracies were greater than 92%. The result indicted that the practice of pen aquaculture experienced five stages, with the general area increasing in the beginning and decreasing by the end of the last stage. Meanwhile, the changes of nine WQ parameters observed from 2000 to 2016, such as ammonia (NH3-N), pH, total nitrogen (TN), total phosphorus (TP), chlorophyll a, biochemical oxygen demand (BOD), chemiluminescence detection of permanganate index (CODMn), Secchi disk depth (SDD) and dissolved oxygen (DO), were analyzed in the lake sectors of Lake Yangcheng, and then their relationships were explored with the percentage of pen aquaculture area. The result suggested that the percentage of pen aquaculture area exhibits significantly positive correlations with NH3-N, TN, TP, chlorophyll a, BOD and CODMn, but significantly negative correlations with SDD and DO. The experimental results may offer an important implication for managing similar shallow lakes with pen aquaculture expansion and water pollution problems.
... The progressive process of eutrophication of surface water leads to the deterioration of water quality. This phenomenon is not only observed in Poland [1,2], but it is also a global problem [3,4]. In many regions of the world there is also a problem of dried-up lakes [5], which results in the need to implement methods for their reconstruction [6]. ...
The eutrophication of surface waters is a natural process; however, anthropogenic activities significantly accelerate degradation processes. Most lakes in Poland and in the world belong to the poor and unsatisfactory water quality class. It is therefore necessary to limit negative anthropogenic impacts and introduce restoration methods, in particular those that are safe for the aquatic ecosystem. One of these is a pulverizing aeration Podsiadłowski method that uses only wind energy. The method allows for the moderate oxygenation of hypolimnion water, which maintains the oxygen conditions in the overlying water zone in the range of 0–1 mg O2·dm-1. The purpose of the work was to develop a new method of determining the efficiency of the aerator pulverization unit in the windy conditions of the lake. The method consists in determining the volumetric flow rates of water in the aerator pulverization unit, based on maximum hourly wind speeds. The pulverization efficiency in the conditions of Góreckie Lake was determined based on 6600 maximum hourly wind speeds in 2018. Based on the determined model, the theoretical performance of the machine was calculated, which in the conditions of Góreckie Lake in 2018 amounted to less than 79,000 m3 per year (nine months of the effective aerator operation).
Shallow lakes are prone to water quality deterioration and are difficult to manage. Turbidity is a physical parameter commonly used to estimate water quality. Revealing the spatiotemporal variations in turbidity can help determine the risk areas of water turbidity to achieve efficient protection and management of water resources. Here, we conducted continuous field observations and monitoring of turbidity in Baoan Lake (114°39′–114°46′E, 30°12′–30°18′N), a shallow lake (average depth: 2.27 m) in southeastern Hubei Province, China, from July 2019 to May 2022, to perform gradient analysis and determine risk levels of water turbidity. Results showed that the average turbidity of the Baoan Lake varied within the range of 9.0–48.8 NTU. Water turbidity fluctuated, reaching peaks in summer or autumn, and troughs in winter. The overall variation of water turbidity in spring and summer ranged within 15 NTU, while in autumn and winter it was over 29 NTU. The turbidity of Zhuti and Qiaodun Lakes (ZL and QL, respectively) was often higher than that of Xiaosihai and Biandantang Lakes (XL and BL, respectively), showing a turbidity decrease from southeast to northwest, especially in winter. A gradient function describing the spatial variation in turbidity was summarized. The parameters of the function had implicit meanings for spatial variations in turbidity. Parameter a influenced the form of the fitting curve. Parameters b and c reflected the range of turbidity values. The two points of the second derivative of the function were considered to indicate the radius of the risk area in a concentric manner. The methodology proposed to identify the risk levels of water turbidity entails the calculation of the risk values for different seasons. Thus, this study provides a new tool for quantifying spatial gradient variation of water turbidity and a new method for determining high-risk areas and risk levels of water turbidity.
