Impact of Water Level Fluctuation on Sediment and Phosphorous Dynamics in Tonle Sap Lake, Cambodia

Khanal, Rajendra; Sovannara, Uk; Kodikara, Dilini; Siev, Sokly; Yoshimura, Chihiro

doi:10.1007/s11270-021-05084-5

Cited by 13 publications

(6 citation statements)

References 30 publications

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“…Field observations conducted by Oyagi et al [19] have shown that water temperatures in the Tonle Sap Lake range from 22 • C to 30 • C throughout the year, and the difference in water temperature between the surface layer and the bottom of the lake is relatively small, indicating that water temperature stratification does not occur. Others have shown that, during the low-water period, the lake becomes eutrophic [28] and the chlorophyll-a and total phosphorus (TP) concentrations reach mesotrophic or eutrophic levels. During the high-water period, both chlorophyll-a and TP concentrations gradually decrease with increasing water level [28].…”

Section: Study Areamentioning

confidence: 99%

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Characteristics of the Annual Maximum and Minimum Water Temperatures in Tonle Sap Lake, Cambodia from 2000 to 2019

et al. 2021

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The Tonle Sap Lake contains unique hydrological environments and ecosystems. Although water temperature is an important consideration in lake management, information on the water temperature of the lake is limited. Thus, we investigated the characteristics of the daytime water temperatures of the Tonle Sap Lake from 2000 to 2019 using MOD11A1, a Moderate Resolution Imaging Spectroradiometers (MODIS) product. Moreover, the relationship between water temperature fluctuations and hydrological–meteorological conditions was analyzed. The maximum and minimum daytime water temperatures were recorded in May (30.7 °C) and January (24.6 °C), respectively, each a month after the maximum and minimum air temperatures were recorded. The annual maximum, average, and minimum water levels showed a downward trend (−0.14, −0.08, and −0.01 m/y, respectively). The annual maximum water temperature increased at a rate of 0.17 °C/decade, whereas the annual minimum water temperature decreased at a rate of 0.91 °C/decade. The annual maximum daytime water temperature had a strong negative correlation with water level change (flood pulse) and a weaker correlation with air temperature. The annual minimum daytime water temperature presented the strongest positive correlation with water level change (flood pulse) in the previous year. However, there was no correlation between the annual minimum daytime water temperature and air temperature. These results indicate that water temperature in the Tonle Sap Lake is mainly affected by water level fluctuations, which are mainly driven by flood pulses.

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Section: Study Areamentioning

confidence: 99%

“…Others have shown that, during the low-water period, the lake becomes eutrophic [28] and the chlorophyll-a and total phosphorus (TP) concentrations reach mesotrophic or eutrophic levels. During the high-water period, both chlorophyll-a and TP concentrations gradually decrease with increasing water level [28].…”

Section: Study Areamentioning

confidence: 99%

Characteristics of the Annual Maximum and Minimum Water Temperatures in Tonle Sap Lake, Cambodia from 2000 to 2019

et al. 2021

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“…On the other hand, the spatial distribution of wind-induced sediment re-suspension has not been thoroughly described and it is necessary to research for sediment re-suspension predictions in large shallow lakes. The impact of water level fluctuation on the sediment dynamics in TSL has been described in a recently published paper [42]. Wave action and subsequent fetches are more likely to cause re-suspension by bottom scouring and are determined by wind speed and fetch [43].…”

Section: Mechanism Of Sediment Re-suspensionmentioning

confidence: 99%

Impact of Wind on the Spatio-Temporal Variation in Concentration of Suspended Solids in Tonle Sap Lake, Cambodia

Sato

Khanal

Sovannara

et al. 2021

Earth

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Even though wind, water depth, and shear stress are important factors governing sediment resuspension in lakes, their actual relations to total suspended solids (TSS) distribution in natural environments have not been well elucidated. This study aims to elucidate the impact of the wind on the spatio-temporal variation of TSS in Tonle Sap Lake, Cambodia, during low-water (March and June, <1 m) and high-water (September and December, 8–10 m) seasons. To this end, wind and TSS data for December 2016 and March, June, and September 2017 were collected and analyzed. For spatial interpolation of wind speed, the inverse distance weighted method was found to be better (R2 = 0.49) than the vectorized average (R2 = 0.30) and inverse of the ratio of distance (R2 = 0.31). Spatial interpolation showed that the wind speed and direction on the lake were <5 m/s and southward during the low-water season and <7 m/s and westward during the high-water season. The TSS concentration in the low-water season was higher (>50 mg/L) than that in the high-water season. The TSS concentration during the low-water season was empirically described by wind speed (W), water depth (D), and shear stress (τ_wave) with a function of W3, W3/D, and exp(W/D) or exp(τ_wave), depending on the location in the lake. The critical shear stress due to wind-induced waves at most of the places in the lake was higher than the total shear stress indicated. Sedimentation was predominant in December and June, and erosion (siltation) was dominant in March. Most of the siltation in March was dominant in the southern part of the lake.

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“…With the impact of natural and anthropogenic activities, water level in lakes fluctuates frequently, showing strong non‐linearity and complexity. More importantly, previous studies have shown that water‐level fluctuation significantly affects lake ecosystems (Cusell et al, 2013; Khanal et al, 2021; Steinman et al, 2012; Wang et al, 2016; Zohary & Ostrovsky, 2011). For example, Zohary and Ostrovsky (2011) found that water‐level fluctuation may weaken keystone species, proliferate nuisance and invasive species, and lead to the loss of biodiversity; the results of Khanal et al (2021) indicated that water‐level fluctuation impacts sediment and phosphorous dynamics in Tonle Sap Lake, Cambodia.…”

Section: Introductionmentioning

confidence: 97%

Daily water‐level forecasting for multiple polish lakes using multiple data‐driven models

Ptak

et al. 2022

Geographical Journal

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Water level in lakes fluctuates frequently due to the impact of natural and anthropogenic forcing. Frequent fluctuations of water level will impact lake ecosystems, and it is thus of great significance to have a good knowledge of water-level dynamics in lakes. However, forecasting daily water-level fluctuation in lake systems remains a tough task due to its non-linearity and complexity. In this study, two deep data-driven models, including gated recurrent unit (GRU) and long short-term memory (LSTM), were coupled with attention mechanism for the forecasting of daily water level in lakes for the first time. Daily water-level times series in five lowland lakes in Poland were used to evaluate the models. Root mean squared error (RMSE) and mean average error (MAE) were used for the evaluation of model performance. The modelling results were compared with the traditional feed-forward neural networks (FFNN), GRU, LSTM, and zero-order forecast. The modelling results showed that sequential deep learning models do not outperform feed-forward models in all cases. In most cases, LSTM with attention mechanism (average RMSE = 0.88 cm, average MAE = 0.69 cm) outperforms GRU with attention mechanism (average RMSE = 1.00 cm, average MAE = 0.81 cm). However, attention mechanism did not help to improve the accuracy of the GRU and LSTM for most cases. Based on the average performance in different lakes, GRU performs the best among the deep learning models (average RMSE = 0.84 cm, average MAE = 0.66 cm).Zero-order forecast models perform better than deep learning models for predicting tomorrow (average RMSE = 0.71 cm, average MAE = 0.39 cm), while deep learning models perform better as the horizon of prediction increases.

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Impact of Water Level Fluctuation on Sediment and Phosphorous Dynamics in Tonle Sap Lake, Cambodia

Cited by 13 publications

References 30 publications

Characteristics of the Annual Maximum and Minimum Water Temperatures in Tonle Sap Lake, Cambodia from 2000 to 2019

Characteristics of the Annual Maximum and Minimum Water Temperatures in Tonle Sap Lake, Cambodia from 2000 to 2019

Impact of Wind on the Spatio-Temporal Variation in Concentration of Suspended Solids in Tonle Sap Lake, Cambodia

Daily water‐level forecasting for multiple polish lakes using multiple data‐driven models

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