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Sediment Management Objective: Securing Quality of Human Life

Sediment Management Objective: Securing Quality of Human Life

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Sediment management objectives and risk indicators


Box 1: Adaptation of the Rhine to human needs and its consequences

Until the beginning of the 19th century, the Upper Rhine still had the

characteristics of a natural river. The first and most momentous adaptation to

human needs started in 1817 with the realisation of the “rectification plans” of

Johann Gottlieb Tulla. Tulla wanted to reduce the destroying effects of the

Rhine waters by straightening the river, by demolition of dams in the water,

and by cutting off its small side arms [77]. He aimed for an increase of

cultivable land, improvement of soil and geographical fixation of the border to

France [78]. Due to these measures, the former width of the Rhine of up to 12

km was narrowed down to 200 to 300 m. Because the bank erosion was

impeded by embankments and groynes, bed erosion increased. In 150 years,

the depth of the Rhine increased by 7 m [79].

In the years that followed Tullas activities, the agricultural use of former flood

plains was intensified through drainage measures, and 12 barrages were built

along the Upper Rhine in order to use hydropower and facilitate shipping. In

the area of the barrages, the river lost 60% of its original flood plains. In

addition, they reduced the natural sediment transport to a large extent. Since

1977, material is artificially added below the last barrage Iffezheim in order to

reduce bed erosion [80].

The Lower Rhine has also increased its depth due to hydraulic engineering

measures during the last 100 years. The sediment dynamics in this area were

further disturbed by extensive gravel withdrawal from the river and by

subsidence of the riverbed as a consequence of underground mining of salt and

coal. In the forming depressions, sediment accumulates and is unavailable for

the river section downstream [79].

An unexpected effect of the straightening of the river was that the time a flood

wave needed to travel down the Upper Rhine was reduced and now overlaps

with the arrival of flood waves from the tributaries at the respective

confluences. This elevates the peak of the water-level of the Rhine floods and

increases their impacts below the confluence of the Neckar [80].

Recently, measures are planned to redo these early modifications of the Rhine

river by re-creating flood plains and re-locating dams. In the area of the Rhinebordering Federal State Nordrhein-Westfalen alone, the provision of

potentially flooded areas with a retention volume of 170 Mio. m3 were planned

in 1996 [81].


J. Joziasse et al.

5.2. Risks involved

Risks and impacts of sediment issues on the quality of human life comprise

quality issues, quantity issues and the perception of risk. An experienced or

continuously perceived risk can ruin the individual's well-being for a long time.

Floods, for example, cause immediate drowning, injuries, and financial losses,

but, probably most important with floods in Europe, they cause an increased

incidence of common mental health disorders. Anxiety and depression may last

for months and possibly even years after the flood event, often not being

recognised in its connection to the natural disaster [82].

Even in cases where from a scientific standpoint risk has disappeared (or never

existed in the first place), perceived risks are real to people and need to be

addressed in management decisions. When a bridge over the Israeli river Kishon

was destroyed and several people died after they fell into the water, media

claimed that they were poisoned by the contact with sediment rather than

drowned, drawing a great deal of attention to the issue of sediment

contamination (Danny Sherban, Yodfat Engineers Ltd, Israel, personal

communication). Even though it is relatively certain that sediment

contamination was not the cause of the deaths, the high level of attention and

concern that this incident raised had to be dealt with.

If risks are not perceived as threatening, but a situation is experienced as

inconvenient, this also has an impact on public welfare and it has economic

consequences. The knowledge that an area is contaminated keeps people from

enjoying its recreational value. If the effects of the contamination can be clearly

appreciated (a film of oil on the water surface, a strange odour), this has a high

negative impact on aesthetics (scenic beauty and public appreciation), even

though no direct threat to human health is involved.

It is, however, difficult to establish causal relationships between human health

and environmental contamination. In many cases, contamination is just one of

several factors including diet and other lifestyle choices, not to mention

genetics, which influence whether an exposed person will ever become sick

[83]. With regard to sediments, it is even more challenging when considering

the different potential exposure pathways and contaminant cocktails.

Nonetheless, human exposure to contaminated sediments is a central part of

tiered approaches to risk assessment and risk management when evaluating

sediment management options. As presented in Chapter 5 (Risk Assessment

Approaches in European Countries), human exposure to contaminated

sediments may occur through direct exposure via sediment ingestion, surface

water ingestion, ingestion of suspended matter, dermal uptake via sediments

Sediment management objectives and risk indicators


and surface water, and indirect exposure via drinking water that has been

affected by contaminated sediment and via consumption of contaminated food.

In general, direct exposure, even to highly contaminated sediments, is usually

too short to create a risk for human health. During swimming, the average

amount that people take in orally is relatively low. Nevertheless, this risk,

especially for small children playing in mud or muddy waters, should not be

excluded. The concerns of Greenpeace on the occasion of the Elbe-Badetag

(Elbe-bathing day) in 2002 (‘Im Gift schwimmen’ (engl.: ‘swimming in

poison’); Greenpeace magazine news Hamburg, May 2002) – although

portrayed very sensationally – were shared by scientists and some regulators. In

most areas, however, concern with regard to adverse effects of recreational

water activities is related to risks caused by pathogenic bacteria (e.g. the

swimming-related fact sheet of the Maryland Department of Health & Mental


In Europe, accumulation of toxic substances in animals that live in direct

contact with sediments and the biomagnification through the food chain is the

most significant exposure route for contaminants in sediment. Until today, the

consumption of fish from many European rivers is still not recommended and

restricted. This especially concerns fish that live in direct contact with sediment

and have a high fat content such as eels. The PCB levels (PCB 153 and PCB

138) in eels from the Mosel, a French-German river, exceeded the allowed

maximum of 0.3 mg/kg and accordingly the environment agency recommended

not to consume this fish species [84].

Another indirect exposure pathway is the intake of drinking water that has been

contaminated after having been in contact with contaminated sediment and

water. Water for public supply comes from two primary sources: surface water

or groundwater. The relative portion varies depending on the natural conditions

and the characteristics of water uses in each country (Table 5). In countries with

extensive groundwater reservoirs (e.g. Iceland, Austria), a major part of total

abstractions comes from this source, compared with less than 15% in the

Netherlands and Finland [85]. While surface water often shows elevated

concentrations of unwanted substances, groundwater is of naturally good

quality and very little or no treatment is needed to make it suitable for drinking.

In case of overexploitation of groundwater resources, however, the groundwater

level can be drawn down, which can influence the movement of water with a

change in quality within an aquifer. Substantial water level lowering can cause

significant quality changes, e.g. pollution because of potential increased

exposure of previously unpolluted groundwater to polluted groundwater

(typically in shallow layers) [86]. This is of particular concern in the

Netherlands, where the high ground water table is in close contact with

contaminated sediments.

J. Joziasse et al.


Table 5: Apportionment of public water supply between groundwaters and surface waters [85].



Groundwater water

(Percentage) (Percentage)












Czech Republic





















Greece (est.)




































Portugal (est.)















Turkey (est.)



England and Wales (NUTS95)




Legend: est. = estimated

Apart from the quality issue, sediment quantity can negatively affect quality of

life by changing the geomorphology of recreational sites such as beaches.

Sediment management objectives and risk indicators


When sediment accumulates in harbour basins, where it has to be dredged again

in order to secure navigation, this can lead to a substantial economic burden on

cities with large ports such as Rotterdam or Hamburg. In Hamburg, the expense

that is incurred by maintenance dredging in the harbour and in the Hamburgdistrict of the Elbe amounts to a total of 18–20 million euros per year. On the

other side, erosion of sediment around bridge girders or piers can also lead to

substantial risks, as has been experienced when the Entre-os-Rios bridge that

partially collapsed in Portugal in 2001 (see Box. 2: The collapse of the bridge

Entre-os-Rios across the Douro River ).

Box 2: The collapse of the bridge Entre-os-Rios across the Douro River

(by Luís Ivens Portela, Research Officer, National Laboratory of Civil

Engineering (LNEC) Portugal)

On March 4, 2001, the bridge at Entre-os-Rios across the Douro River

suffered a partial collapse, causing a bus and several vehicles to fall into the

river. About 60 people were killed. The mechanism for the failure of the

bridge, built in 1885, was the fall of one of the piers due to scour. An enquiry

revealed that over the last three decades the longitudinal profile of the

riverbed experienced a strong and generalised lowering, about 15 m at the

bridge site, but reaching 28 m at other sites. This evolution was certainly due

to the combination of two main factors: the activity of aggregate extraction

from the riverbed and the reduction of sediment discharge caused by sediment

retention in the reservoirs upstream. At the time of the accident, the severe

river flow conditions (discharge 8,000 m3/s) probably caused an additional

lowering of the riverbed, albeit temporary. The enquiry found that the

activities of aggregate extraction were conducted without the support of plans

and technical studies required by existing legislation. There was also an

apparent lack of adequate and effective supervision of these activities. One of

the main recommendations of the enquiry was the need to define and enforce

an integrated approach to sediment management in the Douro River.

5.3. Indicators of risk

The risk indicators for flooding events (in themselves) include an increase in the

number of flooding events, a rise in the average water level, the payment

benefits as well as increased insurance premiums, as listed in table 3. With

regard to the risk to public safety as a result of flood events, these examples of

risk indicators can be expanded also to the number of fatalities, the relocation or

mobility of inhabitants as well as negative public response in opinion surveys.

These risk indicators could apply to both the site-specific and the river basin


J. Joziasse et al.

approach. However, a distinction can be made for risk indicators that only apply

to the risk of public safety at the river basin approach. The river basin approach

accumulates more data and places events in a statistical perspective. Therefore,

it is possible to have additional risk indicators that analyse trends such as claims

for compensation from the governments or the drop in property values.

Historically, human exposure has often been estimated through environmental

measurements of ambient pollutant concentrations. Therefore, monitoring

ambient pollutant levels is critical to measuring exposure for several pollutants

[83]. This approach, combined with information on acceptable or tolerable daily

intake of contaminants, has been used to establish water and sediment quality

standards that often become incorporated into regulatory legislation.

Exceedance of these threshold values is considered an indicator of risk for

human health.

Several environmental pollutants can accumulate in the body over time, often

with increasing risk or harm. These pollutants and their metabolites leave

residues in the body that can be measured, usually in the blood or urine. These

residues reflect the amount of the pollutant in the environment that actually gets

into the body. The approach of measuring pollutant levels in tissue or fluid

samples from organisms or individual people is called biomonitoring.

Environmental exposure to mercury, for example, is of concern as it can be

transformed into methylmercury by bacteria in sediments and then move up the

food chain, accumulating in fish, which are a major source of exposure for

people. Methylmercury has also been associated with harmful effects on the

nervous system, especially in a developing foetus [83].

Another indicator of risk to human health includes the number of fish advisories

in place. National or local authorities issue fish consumption advisories and safe

eating guidelines for waters in order to inform people of the recommended level

of consumption of fish caught in local waters.

Actual incidences of food poisoning or infections are additional examples of

risk indicators at the site-specific scale, whereas statistical trends of food

poisoning or infections are examples of risk indicators at the river basin scale.

Although recreation refers to the recreational activities of the inhabitants of an

area and not tourists that use an area, the damage to recreational activities can

be assessed using some of the indicators that are applicable to the economic loss

from a decline in tourism, as presented in section 3: usage of marinas and other

recreational facilities or the loss of blue flag status for beaches. Indicators of

risk that are appropriate for the more aesthetic aspects related to public welfare

or well-being include the occurrence of eutrophication, noxious odours or

negative press coverage.

Sediment management objectives and risk indicators


5.4. Management options

In order to secure the quality of human life in the event of a flood, public safety

must be ensured. Most of the management options available to do this have

already been presented in section 3. For example, flood protection can be

accomplished by storing flood waters in specially constructed storage or

detention reservoirs or by modifying the river to accommodate the flood flows

within the bank. This can be achieved by widening or dredging the river and by

the construction of flood banks or levees (quays) adjacent to the river.

An additional flood protection management option that is closely linked to the

quality of human life is ensuring public education, communication, and

involvement in the decision-making process. These rights are laid out in The

Aarhus Convention, giving stakeholders the right to obtain information on the

environment, the right to justice in environmental matters and the right to

participate in decisions that affect the government [87]. The right covers

decisions on whether to allow specific activities (for example the construction

of dams), plans and programmes that affect the environment, as well as policies

and laws. Stakeholder participation can lead to decisions that better reflect the

needs of the people and that last longer, as well as decisions that have greater

validity (www.unece.org/env/pp). (see section 6).

Decisions on management options to ensure human health are based on the

information available regarding ambient pollutant concentrations. This

information is obtained through monitoring programs that include measuring

concentrations of contaminants and pathogens in water, sediment and biota

(fish). Biomonitoring that is initiated when there is an indication of risk can

itself be a management option – to indicate sources and monitor improvement

with time.

If pollutant levels in fish and shellfish are unacceptable, issuing advisories can

be an effective management option. Bans can be issued prohibiting all fishing,

or advisories can be issued concerning which species and sizes of fish to avoid.

By discouraging fishing as well as the consumption of fish once caught, public

information is being provided.

Elevated concentrations of contaminants in agricultural products as a result of

crops grown, or cattle grazing on flood plains that have received contaminated

sediment after a flood event are also of concern. Management options include

issuing advisories, increasing efforts to change agricultural land use at the river

basin scale and banning certain agricultural products.

Safeguarding drinking water is essential. Therefore, if elevated concentrations

of contaminants or bacteria in either groundwater drinking water wells or

surface water drinking water reservoirs are measured, management choices

must immediately be implemented. These include dissemination of information,

the use of other sources of water for drinking water and the implementation of


J. Joziasse et al.

additional drinking water treatment processes. Ultimately, the most desirable

management option is source control. Other options are technical remediation

solutions or the installation of adsorptive barriers.

Lastly, risk communication is an important management tool that should always

be implemented together with other management solutions. Risk perception and

communication is presented in detail in section 6. An overview is given in

Table 6.


Sediment management objectives and risk indicators

Table 6: Risk indicators and management options for the objective of securing quality of human



Risk and

driving forces impacts


Flood events,

caused by

change in

land use,

global climate



human safety



High river






material in

flood plains;

Indicator of risk

Management option


River basin



River basin


Negative public

responses in

opinion surveys

Claims for


from the




and involvement


communication /

education and


Payment of


benefits after


Mobility of

people due to

perception of


Collapse in

property values

Flood plain



Payment of



Alteration of

storage /


Cost of incidents capacity

for society

Raising dikes

River deepening

Reduction of

extent of paved


Flood plain


Early warning


Restrictions of

land use

River deepening


welfare (*)

Harm to

human health



Incidences (e.g.

food poisoning,


Evidence or

suspicion for


Use restrictions


of drinking


Biomagnification Source control



Monitoring of

restrictions to


use and

Statistical trends Water and

consumption of

of food

sediment quality fish and







Changes in land


use, settlement


Evidence or

suspicion for



of drinking


Adsorptive layers Source control



treatment of

drinking water

(*) Public welfare includes economic viability; see Table 3

(**) in this context, recreation refers to inhabitants' recreational activities

Use other

sources than

groundwater for

drinking water


J. Joziasse et al.

6. Stakeholder Involvement

It was mentioned at the start of this chapter that the involvement of stakeholders

is necessary in order to comply with the legal requirements and in order to

reduce public resistance and increase tolerance towards risks. As Caddy and

Vergeze put it: “Engaging stakeholders in policy making is a sound investment

and a core element of good governance [88]. It allows governments to tap wider

sources of information, perspectives and potential solutions, and improves the

quality of decisions reached. Equally important, it contributes to building trust

in government, raising the quality of democracy and strengthening civic

capacity.” For a further elaboration on the value of stakeholder involvement in

sediment management, please refer to Chapter 7 - Risk Perception and

Communication in this book and to the book “Sediment management at the

river basin scale”, edited by Phil Owens, this book series. The notions of

stakeholders and public are often used confusedly. ‘Stakeholders’ are defined as

people or organised groups of people who have an effect on or are affected by

sediment management (based on [89]). This definition includes amongst others

lay people, environmental pressure groups, but also companies, semigovernmental organisations, and (decentralised) governments. In other words: a

group of stakeholders can be diverse with regard to professional and educational

backgrounds, interests and rate of organisation. ‘Public’ addresses a large and

broad group such as the citizens of a country. Although the public can be

included in a group of stakeholders once they have an effect on or are affected

by sediment management, the stakeholders are not by definition the same as the

public. Since sediment management and the subsequent risks do not cover

everyone in a society, it is better to speak of stakeholders.

Once a policy maker decides to involve stakeholders in the process, the next

step is to identify the important requirements for stakeholder involvement, and

the initial design of this process. The first step towards an interactive process is

to determine the goal of the process, and consequently the degree of influence

assigned to the stakeholders. This is shown in Table 7.

Note that the level of participation chosen holds consequences for both the

policy makers and the experts. It should be stressed that the decisions

concerning the degree of participation must be communicated towards the

stakeholders so as to avoid disappointments on their part. Disappointments may

rise when stakeholders expect to have a higher degree of influence on the

process than intended by the process manager. Formally, the stakeholders will

not be allowed to have as much influence as they would like to have, which in

turn might result in disappointment, cynicism and decline of support.

Additionally, once a certain degree of stakeholder influence is chosen, this

should not be changed to a lower degree in the course of the process, because

Sediment management objectives and risk indicators


this would provoke the same response as when the initial degree of influence is

not communicated and agreed upon.

Next comes stakeholder selection. As mentioned previously, the stakeholders

can comprise different groups of people, but not all people. The definition used

in this section (see above) gives indications as to whom to select. Some groups

must be selected and approached actively, whereas others will involve

themselves. The differences between the site-specific and river basin scale level

are important to keep in mind. If dealing with a site-specific situation, the

stakeholders identified will be different than when dealing with sediment

management on the river basin scale. In the first case, this will mean involving

stakeholders such as individual farmers, local companies and interests groups

and citizens that are directly affected by the sediment management. At a river

basin scale, on the other hand, stakeholders such as national farmer

organisations, branch organisations and national environmental organisations

are more likely partners in the process. However, in both cases it is very

important that although calculated risk may be low, a person living next to a

sediment depot will be particularly conscious that a risk exists: it does not

matter if the risks are calculated to be high or low. This is because of the

existence of subjective risk perception as discussed in Chapter 7 - Risk

Perception and Communication.

After determining the initial design of the process and selecting the appropriate

stakeholders, the next step is to choose a medium through which the process can

be run. This includes organising workshops, community gatherings, means of

communication and so on (see table 7). It is important to involve the

stakeholders from the start of the process. If they are involved in a later stage,

this might suggest that they are not taken seriously, and they will have very

little influence on the choices that have been made. Disappointed stakeholders

will surely use their obstructive power and the process will become frustrated.

The case of the Ingensche Waarden in the Netherlands (see Box 3) shows the

negative impact of stakeholder obstruction on the progress of the process.

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