Sensitivity Analysis of Annual Nitrate Loads and the Corresponding Trends in the Lower Illinois River

Markus, Momcilo; Demissie, Misganaw; Short, Matthew B.; Verma, Siddhartha; Cooke, Richard A.

doi:10.1061/(asce)he.1943-5584.0000831

Cited by 32 publications

(19 citation statements)

References 25 publications

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“…Such extreme dry and wet periods are typically not well-represented with historical data and can, therefore, be difficult to model with regression-based load estimation techniques. 33 For example, Murphy et al 8 found that modeled (WRTDS) NO 3 − concentrations in the Mississippi River basin were 8−21% lower than expected when the previous year was 50% wetter than average. The large mass differences in the spring of 2013 clearly suggest the difficulty in predicting anomalously high NO 3 − concentrations following a drought.…”

Section: Comparison Of Modeled and Measured Loads A Comparison Of Thmentioning

confidence: 99%

“…However, these differences may be accentuated during extreme climatic periodsas observed during the drought-to-flood years in our studywhere concentrationdischarge relationships ( Figure 4) are not well-represented by historical data and are particularly difficult to model. 33 The NO 3 − load estimates based on a linear interpolation of discrete concentration data may better characterize anomalies in NO 3 − concentrations than regression-based approaches, but that is entirely dependent on the frequency and distribution of discrete samples. 21 On a per sample basis, the cost of continuous NO 3 − monitoring in a large river like the Mississippi is very small compared to discrete sample collection, which may cost up to several thousand dollars per sample when factoring in personnel, equipment and lab analyses.…”

Section: Comparison Of Modeled and Measured Loads A Comparison Of Thmentioning

confidence: 99%

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Mississippi River Nitrate Loads from High Frequency Sensor Measurements and Regression-Based Load Estimation

Pellerin

Bergamaschi

Gilliom

et al. 2014

Environ. Sci. Technol.

111

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Accurately quantifying nitrate (NO3-) loading from the Mississippi River is important for predicting summer hypoxia in the Gulf of Mexico and targeting nutrient reduction within the basin. Loads have historically been modeled with regression-based techniques, but recent advances with high frequency NO3- sensors allowed us to evaluate model performance relative to measured loads in the lower Mississippi River. Patterns in NO3- concentrations and loads were observed at daily to annual time steps, with considerable variability in concentration-discharge relationships over the two year study. Differences were particularly accentuated during the 2012 drought and 2013 flood, which resulted in anomalously high NO3- concentrations consistent with a large flush of stored NO3- from soil. The comparison between measured loads and modeled loads (LOADEST, Composite Method, WRTDS) showed underestimates of only 3.5% across the entire study period, but much larger differences at shorter time steps. Absolute differences in loads were typically greatest in the spring and early summer critical to Gulf hypoxia formation, with the largest differences (underestimates) for all models during the flood period of 2013. In additional to improving the accuracy and precision of monthly loads, high frequency NO3- measurements offer additional benefits not available with regression-based or other load estimation techniques.

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Section: Comparison Of Modeled and Measured Loads A Comparison Of Thmentioning

confidence: 99%

Section: Comparison Of Modeled and Measured Loads A Comparison Of Thmentioning

confidence: 99%

Mississippi River Nitrate Loads from High Frequency Sensor Measurements and Regression-Based Load Estimation

Pellerin

Bergamaschi

Gilliom

et al. 2014

Environ. Sci. Technol.

111

View full text Add to dashboard Cite

show abstract

“…An innovative trend analysis (ITA) method, recently introduced by Şen (, ), has been used for detecting trends in environmental, hydrological and meteorological variables (e.g. Markus et al , ; Ay and Kisi, ; Kisi, ; Onyutha, ; Tabari and Willems, ). Martínez‐Austria et al () analysed temperature and heat wave trends in Northwest Mexico by data linear adjustment, Spearman test and ITA and all of the analyses indicated the existence of a process of heating with increasing maximum temperature.…”

Section: Introductionmentioning

confidence: 99%

Innovative trend analysis of annual and seasonal rainfall and extreme values in Shaanxi, China, since the 1950s

Qian

2016

Intl Journal of Climatology

240

109

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Rainfall is a primary component of the water cycle, and its variability is associated with drought and flood events. This study investigates the trends in annual and seasonal rainfall at 14 rainfall stations in Shaanxi Province, China, using an innovative trend analysis (ITA), Mann–Kendall test and linear regression analysis. Moreover, using ITA, annual rainfall is analysed for different rainfall intensities, and seasonal rainfall is analysed for extreme values. The results show non‐uniform trends in rainfall intensities on a regional and seasonal scale. Annual rainfall shows a significant decreasing trend in the Wei River Basin and north of the Loess Plateau. Overall, the trend is reinforced with the increase of rainfall intensity. A few stations show significant trends in seasonal rainfall. Spring rainfall is the major contributor to the decline in annual rainfall. Heavy rainfall (more than 90th percentile) in summer exhibits a marked downward trend mainly in the basin, which makes it possible for flooding to abate along the Wei River. Light rainfall (less than 10th percentile) shows a prevailing increasing trend in summer, but a decreasing trend in other seasons. From north to south, the seasonal trends become clearer and stronger. In terms of management, more attention should be paid to autumn droughts in the Wei River Basin. A quantitative measurement of a trend for ITA is proposed. Comparison of the three methods endorses the ITA method. Moreover, the ITA shows many advantages, such as graphical results and for observing sub‐trends. It is hoped that this study can provide support for water resources planning, for coping with droughts and floods and for future development of the ITA method.

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“…Therefore, there is no obstacle in the application of this method to any kind of time series for trend identification. The advantages of this method are highlighted by many researchers (Sonali and Nagesh Kumar, ; Timbadiya et al ., ; Markus et al ., ; Şen, ; Saplioglu et al ., ; Kisi and Ay, ; Ay and Kisi, ; Mishra and Coulibaly, ; Haktanir and Citakoglu, ). It is also possible that the trend in time series can be displayed clearly as monotonic or nonmonotonic via this method (Şen, ).…”

Section: Introductionmentioning

confidence: 99%

Climate change and frequency–intensity–duration (FID) curves for Florya station, Istanbul

Güçlü

Şişman

Yeleğen

2016

J Flood Risk Management

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In recent decades, according to Intergovernmental Panel on Climate Change reports, the impact of climate change on hydro‐meteorological events has increased substantially. This point is obvious in many rainfall–runoff time series as a negative or positive trend. In this paper, first of all such trend possibilities are searched graphically according to Şen's 1:1 (45°) straight‐line method, which has been proposed instead of the classical methods including Mann–Kendall, Spearman's rho and linear regression approaches. Additionally, these trends are quantified by using frequency–intensity–duration (FID) curves, instead of intensity–duration–frequency (IDF) curves obtained from a set of single storm rainfall records. The FID curves provide practical, easy and clear representation of rainfall intensity variation through fitted exponential curves with coefficient of determination that is almost equal to 1 (R2 ≈ 1). FID curves are drawn on semilogarithmic paper with rainfall intensity estimations from the convenient Gamma probability distribution functions (PDFs) or cumulative distribution functions (CDFs). In this study 46‐year rainfall records are used from Florya station, which is located in Istanbul, Turkey. The comparisons generally indicated that a negative trend is valid at this station, and accordingly, representative FID curves are obtained on ordinary and semilogarithmic papers for this station.

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Sensitivity Analysis of Annual Nitrate Loads and the Corresponding Trends in the Lower Illinois River

Cited by 32 publications

References 25 publications

Mississippi River Nitrate Loads from High Frequency Sensor Measurements and Regression-Based Load Estimation

Mississippi River Nitrate Loads from High Frequency Sensor Measurements and Regression-Based Load Estimation

Innovative trend analysis of annual and seasonal rainfall and extreme values in Shaanxi, China, since the 1950s

Climate change and frequency–intensity–duration (FID) curves for Florya station, Istanbul

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