Improving the predictive power when modelling physical effects of human interventions in estuarine systems

Schuttelaars, Henk M.; Jonge, Victor N. de; Chernetsky, Alexander S.

doi:10.1016/j.ocecoaman.2012.05.009

Cited by 70 publications

(51 citation statements)

References 28 publications

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“…Quite recently, considerable attention has been paid to evaluate the effect of climate change (Fettweis et al, 2012) and human interventions (Schuttelaars et al, 2013;Winterwerp and Wang, 2013;Yang et al, 2013;De-Jonge et al, 2014) on natural distribution of SPM in estuaries. There is numerical evidence linking freshwater abstractions to an increased potential for up-estuary transport .…”

Section: Introductionmentioning

confidence: 99%

Turbidity in the fluvial Gironde Estuary (southwest France) based on 10-year continuous monitoring: sensitivity to hydrological conditions

Jalón‐Rojas

Schmidt

Sottolichio

2015

Hydrol. Earth Syst. Sci.

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Abstract. Climate change and human activities impact the volume and timing of freshwater input to estuaries. These modifications in fluvial discharges are expected to influence estuarine suspended sediment dynamics, and in particular the turbidity maximum zone (TMZ). Located in southwest France, the Gironde fluvial-estuarine system has an ideal context to address this issue. It is characterized by a very pronounced TMZ, a decrease in mean annual runoff in the last decade, and it is quite unique in having a long-term and highfrequency monitoring of turbidity. The effect of tide and river flow on turbidity in the fluvial estuary is detailed, focusing on dynamics related to changes in hydrological conditions (river floods, periods of low discharge, interannual changes). Turbidity shows hysteresis loops at different timescales: during river floods and over the transitional period between the installation and expulsion of the TMZ. These hysteresis patterns, that reveal the origin of sediment, locally resuspended or transported from the watershed, may be a tool to evaluate the presence of remained mud. Statistics on turbidity data bound the range of river flow that promotes the upstream migration of TMZ in the fluvial stations. Whereas the duration of the low discharge period mainly determines the TMZ persistence, the freshwater volume during high discharge periods explains the TMZ concentration at the following dry period. The evolution of these two hydrological indicators of TMZ persistence and turbidity level since 1960 confirms the effect of discharge decrease on the intensification of the TMZ in tidal rivers; both provide a tool to evaluate future scenarios.

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Section: Introductionmentioning

confidence: 99%

Turbidity in the fluvial Gironde Estuary (southwest France) based on 10-year continuous monitoring: sensitivity to hydrological conditions

Jalón‐Rojas

Schmidt

Sottolichio

2015

Hydrol. Earth Syst. Sci.

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“…Despite this finding, the average water turbidity in our analysis was only a weak predictor for explaining the monthly variation in chl a concentrations. This is remarkable because apart from the reported wind driven natural variation in SPM concentrations (de Jonge 1995a, de Jonge & van Beusekom 1995, there is also a major (since 1970s) anthropogenic component in this estuary caused by channel maintenance dredging, the disposal of harbour sludge (de Jonge 1983) and major engineering works in the freshwater tidal river Ems itself since the mid 1980s with significant implications for the entire system (Schuttelaars et al 2012). The result of the dredging activities was a ~2-to 3-fold SPM increase in the main channels of the main estuary during the early 1990s compared to 1954, and of which the effects are also measurable during high water above the submerged intertidal flats (de Jonge 1995a, de Jonge & van Beusekom 1995.…”

Section: Turbidity and Lightmentioning

confidence: 98%

Long-term mean annual microphytobenthos chlorophyll a variation correlates with air temperature

Jonge¹,

Boer²,

Jong³

et al. 2012

Mar. Ecol. Prog. Ser.

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Long-term interannual variations in the mean microphytobenthos chlorophyll a (chl a) of the Ems estuary were investigated. Concentrations in the 1990s were on average 1.5 times higher than during the period from 1976 to 1978, but a trend in chl a over the entire period (1976 to 1999) was not found. In agreement with findings from the late 1970s, the mean chl a concentrations over the post 1990 period correlated significantly with the station elevation related exposure time. Over the entire 1976 to 1999 study period, the estuary mean annual chl a concentrations correlated strongly and significantly with the mean annual air temperature. Although the range of the variation in the mean annual air temperature of the studied years was only 7.5 to 10.2°C, it surprisingly corresponded with a ca. 2.5-fold variation in the mean annual microphytobenthos chl a. In addition to chl a, mean monthly C:chl a ratios from 1976 to 1977 also correlated positively with changes in temperature. Microphytobenthos carbon biomass [chl a × (C:chl a)] may, therefore, respond even stronger to air temperature than chl a does. The correlations are most likely a combination of direct temperature effects on microphytobenthos and stronger, probably complex, indirect temperature effects on the seasonal development and standing stock of young and adult grazers (bivalves) and their carnivores like the brown shrimp Crangon crangon.

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“…Examples of such estuaries are the Ems River, where the average concentration at the surface has increased from 200 mg/L in the 1950s to over 1 g/L now (e.g. Talke et al 2009;Schuttelaars et al 2013;De Jonge et al 2014), and the Loire River, where the average concentration near the surface has increased from around 500 mg/L in the 1970s to several grammes per litre now (Jalón-Rojas et al 2016). This dramatic increase in suspended sediment concentration has a severe negative impact on light penetration and oxygen conditions, resulting in a strong reduction in primary production (e.g.…”

Section: Introductionmentioning

confidence: 99%

The hyperturbid state of the water column in estuaries and rivers: the importance of hindered settling

2018

Self Cite

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Over the last few decades, some estuaries have undergone a transition to a hyperturbid state, characterised by suspended sediment concentrations of several grammes per litre averaged over the water column. To improve our understanding of this transition and of naturally hyperturbid estuaries, we systematically identify the processes allowing for high suspended sediment concentrations using a water column (1DV) model. Under a range of realistic forcing conditions, the state of the water column can be characterised by one of two equilibrium states. The first is an erosion-limited state, in which there still is sediment available for erosion at the bed. We find that this state only occurs with relatively low concentrations. The second is a supply-limited state, in which all erodable sediment is in suspension. The concentration in this state depends entirely on the amount of sediment in the system and can potentially be very high. We identify the conditions under which the state of the water column can jump from a low to a high concentration and identify hysteresis in the transition between the two states. The mechanism responsible for this hysteresis is hindered settling. It thus follows that hyperturbidity is only possible in a supply-limited state. From this observation we derive a necessary condition for an estuarine system to make the transition from low turbidity to hyperturbidity in a 1DV context. This is an important step towards understanding why some estuaries are hyperturbid and assessing the risk that particular estuaries may become hyperturbid in the future.

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Improving the predictive power when modelling physical effects of human interventions in estuarine systems

Cited by 70 publications

References 28 publications

Turbidity in the fluvial Gironde Estuary (southwest France) based on 10-year continuous monitoring: sensitivity to hydrological conditions

Turbidity in the fluvial Gironde Estuary (southwest France) based on 10-year continuous monitoring: sensitivity to hydrological conditions

Long-term mean annual microphytobenthos chlorophyll a variation correlates with air temperature

The hyperturbid state of the water column in estuaries and rivers: the importance of hindered settling

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