Estimation of long-term external nutrient loading from watersheds to Lake Biwa by a combined rainfall-runoff model and loading-discharge curve approach

Tien, Huu Le; Okubo, Kenji; Thi, Phuong Ho; Saito, Mitsuyo

doi:10.3178/hrl.14.143

Cited by 6 publications

(4 citation statements)

References 28 publications

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“…The tank model devised by Sugawara (1972) was convinced by the researchers for a long-term analysis over centuries. A recent application of the model by Le et al (2020) demonstrated the loading procedures through flux paths of surface and subsurface discharge from multiple watersheds into a deep lake. An overview of the model in this study is shown in Figure 2, where the routine is based on water depth in each story of the tanks arranged in series.…”

Section: Runoff Modelmentioning

confidence: 99%

“…In this study, following Amano and Kazama (2012) and Le et al (2020), the relationship among gravimetric C i (g/m 3 ), dissolved chemical constituent loads L i (g/s), and discharge Q (m 3 /s) is shown in Equation 10.…”

Section: L-q Curvementioning

confidence: 99%

“…The load-flow curve (i.e., L-Q curve) is an empirical formula for load (L) and flow (Q), and after deriving the L-Q curve, the loads can be calculated from the flow value. The L-Q curve is mainly used to estimate the impact of anthropogenic pollution (Yokota et al, 2013;Miyazako et al, 2014;Sugai et al, 2016;Le et al, 2020), and few examples of its use in elucidating the process of water quality formation in saline lakes are reported. However, quantitative understanding of the chemical constituents flowing into saline lakes will lead to future predictions on the increase and decrease of salinity and to an understanding of the mechanism of water quality formation in saline lakes.…”

Section: Introductionmentioning

confidence: 99%

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Mass balance of saline lakes considering inflow loads of rivers and groundwater: the case of Lake Issyk-Kul, Central Asia

2021

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This study aimed to elucidate the influence of inflow water on the salinity concentration process of a saline lake and the mass balance of Lake Issyk-Kul, a tectonic saltwater lake in Kyrgyzstan. Based on the survey results and meteorological data from 2012 to 2015, we analyzed the dissolved chemical composition loads due to water inflow. Then, we discussed the relationship between the increase in salinity and water inflow into the lake. Through the water quality analysis data, we used the tank model to estimate the river inflow and analyze the loads by the L-Q curve. The groundwater loads were then estimated from the average annual increase in salinity of the lake over a period of 30 a. The results suggest that Lake Issyk-Kul was temporarily freshened between about AD 1500 and 1800 when an outflowing river existed, and thereafter, it became a closed lake in AD 1800 and continued to remain a saline lake until present. The chemical components that cause salinization are supplied from the rivers and groundwater in the catchment area, and when they flow into the lake, Ca 2+ , HCO 3 − and Mg 2+ precipitate as CaCO 3 and MgCO 3 . These compounds were confirmed to have been left on the lakeshore as evaporite. The model analysis showed that 1.67 mg/L of Ca 2+ and Mg 2+ supplied from rivers and groundwater are precipitated as evaporite and in other forms per year. On the other hand, salinity continues to remain in the lake water at a rate of 27.5 mg/L per year. These are the main causes of increased salinity in Lake Issyk-Kul. Since Na + and Clare considered to be derived from geothermal water, they will continue to flow in regardless of the effects of human activities. Therefore, as long as these components are accumulated in Lake Issyk-Kul as a closed lake, the salinity will continue to increase in the future.

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Section: Runoff Modelmentioning

confidence: 99%

Section: L-q Curvementioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Mass balance of saline lakes considering inflow loads of rivers and groundwater: the case of Lake Issyk-Kul, Central Asia

2021

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“…Evaluation of discharge loads (L) for non-point contamination sources has been receiving increasing attention (e.g. Tien et al, 2020). That paper used a loading (L) -discharge (Q) curve approach, in this study, we use the term, "L-Q relationship" or "L-Q equations".…”

Section: Introductionmentioning

confidence: 99%

Analyzing the bias in dry weather spot flow rates to periodical mean flow rates in mountain streams: toward determining water pollution loads and optimizing water sampling strategies

Tanno¹,

Harada

2021

Hydrological Research Letters

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Low frequency (once a month) but long-term (ca. 6 years) sampling including snow-melt periods in a mountainous stream, the Okura River (Sendai, Japan), revealed that loadings of 5 parameters (COD, TN, TP, TOC and D-SiO 2 ) could be expressed exponentially using discharge (Q), while the coefficients for the 5 loadings were all about 1. Here, mathematically, the periodically averaged Q leads to approximation of that of load (L). We analyzed the bias of the spot Q to that of the periodical (30, 14 and 8 days) means. The results ensured the utilization of the spot Q instead of the periodical mean Q for estimating L because of the high correlation factors (0.872, 0.914 and 0.923 on 30-, 14-, 8-day mean Q analyses, respectively) and suggested the validity of the usage of the observed regression slopes of 1.06, 1.22, and 1.22 over 30, 14, 8 days for quantitative correction of L because the fact that the slopes are larger than 1 indicate that the usage of the spot Q instead of the mean Q leads to the overestimation of L. Both changing correlation factors and the regression slopes realized small improvements via shortening the periods from 14 to 8 days. The protocol proposed here is quite original and is applicable to designing sampling strategies at target sites based on quantification of the limitations and/or reliability of L estimations.

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Modeling of comprehensive power load of fishery energy internet considering fishery meteorology

Gou

2023

Information Processing in Agriculture

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Estimation of long-term external nutrient loading from watersheds to Lake Biwa by a combined rainfall-runoff model and loading-discharge curve approach

Cited by 6 publications

References 28 publications

Mass balance of saline lakes considering inflow loads of rivers and groundwater: the case of Lake Issyk-Kul, Central Asia

Mass balance of saline lakes considering inflow loads of rivers and groundwater: the case of Lake Issyk-Kul, Central Asia

Analyzing the bias in dry weather spot flow rates to periodical mean flow rates in mountain streams: toward determining water pollution loads and optimizing water sampling strategies

Modeling of comprehensive power load of fishery energy internet considering fishery meteorology

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