A preliminary pressure–impact analysis applied in the Pinios riverbasin (Thessaly, Central Greece)

Alexis Ioannou1, Yorgos Chatzinikolaou1,2 & Maria Lazaridou1

1Laboratory of Zoology, Department of Biology, Aristotle University of Thessaloniki, Thessaloniki, Greece and 2Institute of Inland Waters, Hellenic Centre

for Marine Research, Anavissos, Greece

Keywords

hydromorphology; IMPRESS analysis; pollution;

risk assessment; river basin management; River

Habitat Survey; River Pinios; Water Framework

Directive.

Correspondence

Alexis Ioannou, Laboratory of Zoology,

Department of Biology, Aristotle University of

Thessaloniki, GR-54124 Thessaloniki, Greece.

Email: aioannou82@gmail.com

doi:10.1111/j.1747-6593.2008.00130.x

Abstract

Greece has not yet undertaken one of the first and most important tasks

required by the Water Framework Directive (WFD: the integrated review of the

impact of human activity on the status of surface waters for each river basin –

the IMPRESS analysis. Owing to the lack of a national methodology, a

preliminary analysis was carried out for the Pinios river basin, applying a

combination of different methodologies refined to suit the particularities of the

Greek freshwater environment and to accommodate the limited availability of

data. Pressures caused by the main pollution sources, point and nonpoint, were

quantified in terms of pollution loads with the use of emission factors. The

existing limited biological and physicochemical monitoring data were used to

assess impacts. Additionally, we identified pressures caused by alterations from

land-use data; we carried out a River Habitat Survey (RHS) and estimated the

hydromorphological impacts through the calculation of a Habitat Modification

Score (HMS). Our results suggest that the probability of the Pinios river basin

failing to achieve good ecological quality by 2015 due to pollution is high, and

due to hydromorphological pressures is moderate.

Introduction

The key objective of the Water Framework Directive

2000/60 (WFD) is to achieve good ecological and chemi-

cal conditions by 2015 for all European Union (EU)

natural inland waters (European Union Council 2000).

Pressure (defined here as the quantification of an anthro-

pogenic activity that may have an effect on the environ-

ment, that is the pollution load produced by an industrial

unit) and impact (IMPRESS) analysis plays a key role in

this process as it evaluates the likelihood that a water

body will fail to meet set objectives (CIS Working Group

2.1: IMPRESS 2003). This analysis is carried out according

to the Driving force–Pressure–State–Impact–Response

(DPSIR) framework that represents the ways in which

society, the economy and the natural environment inter-

act (Kristensen 2004). On this basis, the regulatory

authorities can create a focused monitoring programme

for regions in danger and adjust the River Basin Manage-

ment Plan (RBMP) accordingly.

There are four stages to IMPRESS analysis: (a) identifi-

cation of driving forces and pressures, (b) identification of

potentially significant pressures, (c) impact assessment

and (d) evaluation of the likelihood of failing to meet the

environmental objectives. The first stage is the evaluation

of driving forces and the pressures they exert. Specifically,

these pressures are from point sources (industry and

housing), nonpoint sources (e.g. livestock grazing, arable

farming, forestry) and hydromorphological alterations.

Although most types of pressures should be assessed, due

to the preliminary nature of the analysis, only the most

important ones were calculated. Pressures arising from

habitats that are very likely to affect community struc-

ture, including the loss of rare or hydromorphological

alterations, can result in a loss or change in endangered

species. Secondly, there is a need to identify whether

current pressures are significant, that is, pressures that

cause an impact that may lead to a failure to achieve the

specified objectives (CIS Working Group 2.1: IMPRESS

2003). One simple but effective approach is to compare

the magnitude of the pressure with a criterion or a

threshold. After having identified the significant pres-

sures, estimation and quantification of the impacts

on the water should be carried out – a step that uses

results from existing monitoring programmes. Moreover,

it must be kept in mind that most pressures do not create a

Water and Environment Journal 23 (2009) 200–209 c� 2008 The Authors. Journal compilation c� 2008 CIWEM.200

Water and Environment Journal. Print ISSN 1747-6585

clear-cut impact, but substantially change the probability

of adverse conditions (CIS Working Group 2.1: IMPRESS

2003). Finally, the evaluation of the likelihood of failing

to meet the objectives is a risk assessment process and,

ideally, it should be estimated by comparing the ecological

state of the waters with threshold values. Because these

threshold values are not currently available, it is neces-

sary to compare the mean preliminary values with the

assessed impacts and, taking into account whether the

pressures applied are significant or not, derive two or

three risk levels.

The aims of the present study are: (i) to produce a

preliminary methodology for IMPRESS analysis of Greek

rivers, (ii) to identify and evaluate different methodolo-

gies used in other EU Member States and to apply them to

the Pinios river basin and (iii) to identify data deficiencies

and methodological improvements. It is important to note

that as this is a preliminary evaluation based on approx-

imate quantification of pressures and limited monitoring

data, it is likely to contain many uncertainties (UKTAG

2004). As more data are acquired and as more IMPRESS

analyses are carried out the greater will be the accuracy of

subsequent evaluations.

Study area

The Basin of the Pinios River is situated in the Water

District of Thessaly (391340N, 22180E), Greece. Figure 1

shows a map of the basin together with the sampling sites

listed in Table 8. The analysis was performed for the entire

river basin instead of for each separate water body as

recommended (CIS Working Group 2.1: IMPRESS 2003)

due to lack of adequate data for each water body. It was

assumed that the river basin contains the administrative

regions at the NUTS3 level that belong to the Water

District minus all regions of the Magnesia Prefecture.

Administrative divisions were used instead of hydrological

ones because all existing pressure data are available at this

level. The total extent of the Pinios river basin is

11 318 km2 (including the former Karla Lake basin) and

the mean water discharge is 86.1 m3/s according to the

Greek National Bank of Hydrological and Meteorological

Information. The largest part of the river flows through

the country’s largest cultivated plain and has predomi-

nantly smooth gradients. The largest part of the river basin

is used for the intensive cultivation of cotton, corn and

sugar. The cultivation of these crops requires large quan-

tities of water, 96% of which is drawn from the Pinios

(Greek Ministry of Development 2003). The industrial

sector, on the other hand, is not very developed and

consists mainly of food processing. The main water uses,

as designated by Trikala Prefectural Decision 4813/98

(1998), are irrigation and machine cooling. All other uses

are also approved except drinking, swimming and fishing.

Methods

Pressures from pollution sources

The conceptual model used to describe the process of

production and transport of wastewater from point and

diffuse sources is presented in Fig. 2. Water users are

separated into three groups: domestic, industrial and

agricultural (including livestock rearing). Each produces

a certain amount of wastewater expressed in kg/day and

designated as emissions. The amount of each emission

that enters surface waters after dispersal, transportation

and/or purification is called ‘input’. Inputs are then

compared with the maximum permitted input loads

[environmental quality standards (EQS) as defined for

irrigation, drinking and fish life multiplied by the mean

daily discharge of the Pinios] to determine the reduction

Fig. 1. Location of the 13 sampling stations on

the Pinios River basin, Greece.

Water and Environment Journal 23 (2009) 200–209 c� 2008 The Authors. Journal compilation c� 2008 CIWEM. 201

IMPRESS analysis applied in the Pinios river basinA. Ioannou et al.

in input loads required to comply with different environ-

mental management goals. The loads’ calculation is based

on the use of emission factors and is done for the entire

river basin for organic pollution [biological oxygen de-

mand (BOD)] and eutrophication (Total N, Total P).

Point sources of pollution

The loads produced by industrial units were taken directly

from the Greek national census of liquid wastes (LDK EPE

et al. 2001), which includes the largest and most polluting

units but unfortunately not all of the remainder. In order

to calculate emissions from domestic housing, the resi-

dent population was divided into three groups: those

served by a Waste Water Treatment Plant (WWTP) those

who are connected to a drainage network but not to a

WWTP and those who process their wastes independently

using septic tanks. Emissions to and inputs from WWTPs

were taken directly from Argyrouli et al. (2005). For the

calculation of the inputs of the other two groups, the

emission factors in Table 1 were used (Fribourg Blanc &

Courbet 2004; Argyrouli et al. 2005) after making the

assumption that in the drainage networks there are no

losses and decomposition of the wastes does not occur.

Nonpoint sources of pollution

Nonpoint sources of pollution were diffuse pollutants

derived from the different land uses and livestock breed-

ing. The different land uses are as determined by Corine

Land Cover 2000 (EEA 2007). They are grouped into five

categories (Table 2) and each category is assigned to a

different input factor. The emissions produced from live-

stock breeding activities were calculated based on the

number and species of breeding animals (data from Greek

National Statistical Service) using the emission factors

shown in Table 3. Of the emissions produced according

to these factors, 20% of the BOD, 15% of N and 3% of P

form the inputs and are assumed to be transported in

the surface waters (Central Greek Water Agency 2006;

Andreadakis et al. 2007).

Hydromorphological alteration pressures

A River Habitat Survey (RHS) was conducted at 402 sites

of 500 m length each along the main channel of the Pinios

during the summer of 2003. RHS is a system for evaluat-

ing the character and quality of the natural structure of a

river and was developed by the UK Environment Agency

(Raven et al. 1998). In order to identify the main hydro-

morphological alteration pressures, the following steps

were undertaken: data were collected in the field using a

modification of the RHS protocol developed by the UK

Environment Agency (pers. comm. with M. Naura on

standard RHS 2003 protocol) and then inserted into the

standard RHS database. Rare features, defined as features

Drivingforces

Emission

Impact

Inputreduction

Surfacewaterquality

Input

Emission reduction

Pressure

ResponseMeasures

State

Fig. 2. The conceptual model used in relation to the DPSIR model

(modified from VMM 2001).

Table 1 Emission factors for urban wastewater and septic tanks

(Fribourg Blanc & Courbet 2004)

Pollutant Network (g/inhab. day) Tanks (g/inhab. day)

BOD 63 36

Total N 11 10.8

Total P 4.5 2.4

BOD, biological oxygen demand.

Table 2 Nutrient export coefficients for each land use category (WL-Delft

et al. 2005)

Land use Total N (kg/ha year) Total P (kg/ha year)

Surface waters 1.2 0.01

Forested areas 3 0.1

Grasslands 5 0.5

Agricultural area 30 0.5

Urban area 5 1

Table 3 Emission factors for livestock breeding

Animal type

Emission factor (g/animal day)

BOD Total N Total P

Bovines 675 202.5 22.5

Sheep and goats 100.2 24.6 4.2

Pigs 80 38.4 11.2

Horses 381.5 31.5 7

Poultry 3.825 0.825 0.55

BOD, biological oxygen demand.

Water and Environment Journal 23 (2009) 200–209 c� 2008 The Authors. Journal compilation c� 2008 CIWEM.202

IMPRESS analysis applied in the Pinios river basin A. Ioannou et al.

of important ecological value present in o5% of the sites,

were identified.

Identification of significant pressures

The pressures from pollution sources are considered sig-

nificant if the total inputs to surface waters are greater

than the maximum permitted loads (obtained by multi-

plying the mean daily discharge with the specific EQS) for

fish life (Trikala Prefectural Decision 4813/98 1998). The

fish life environmental standard was selected as it is the

only standard that can provide an indication of ecological

quality. We do not differentiate between point and non-

point pollution because we suppose that their effect is

synergetic. The hydromorphological alteration pressures

are considered significant if the agricultural land covers

more than 40% of the total extent of the river basin

(LAWA 2002) or if the urban land covers more than 2.5%

of the total extent of the river basin (European Environ-

ment Agency 2005).

Impact assessment

In accordance with the WFD, physicochemical and biolo-

gical quality elements were used to assess the impact of

pollution on surface waters. Timelines from 1980 to 2001

of three chemical components in one station (Ydatopyr-

gos Larisas) were created using data from the Greek

Ministry of Agriculture, the only authority that possesses

long-term chemical quality data. The time series is not

complete because sampling was occasionally not carried

out. In order to fill the gaps, the following equation was

used (Skoulikidis 2002):

Xmissing monththe year Y

¼Averageof the rest months of

the year Y�Averageof the missing month X

in the rest of the years

Averageof the other months of all other years

:

Additionally, chemical data from the new national

monitoring network established by the Ministry of Envir-

onment were used at 13 sites. The sampling had taken

place every 4 months from 2001 to 2003. Finally, biologi-

cal water quality was assessed at 56 sites along the main

channel of the River Pinios and some of its tributaries.

Benthic macroinvertebrate sampling took place during

autumn 2002 (Chatzinikolaou & Lazaridou 2007) and

was semiquantitative. Biological quality was first standar-

dised in relation to habitat richness (Chatzinikolaou et al.

2008) according to the Greek Habitat Richness Matrix

(Chatzinikolaou et al. 2006) and classified into five classes

as required by the WFD using the Hellenic Evaluation

Score (HES) (Artemiadou & Lazaridou 2005). No compar-

ison with reference conditions for similar river types was

performed due to lack of such data. However, the HES

does not require such a comparison in order to classify the

ecological state, based on benthic macroinvertebrates,

into a five-scale band.

In order to assess the impacts from hydromorphological

pressures, data from the RHS were used to estimate the

extent of artificial modification through calculation of a

Habitat Modification Score (HMS). This is a score that

calculates the modification of the natural site structure

using a subjective scoring system (Raven et al. 1998). Sites

can then be classified as a Habitat Modification Class

(HMC) (Table 4) and compared directly with each other.

The next step is to classify water bodies (the river basin

in this case) into three groups depending on the certainty

of the impacts that they exhibit: those with certain

impacts, those with probable impacts and those without

impacts (either from pollution or from hydromorphologi-

cal alterations). Classification (Table 5) is based on exist-

ing monitoring data and can be flexible depending on

data availability (Castro et al. 2005). The results of this

classification may not be statistically robust as they are

based on expert judgement. They are, however, directly

comparable with each other, quite strict in defining water

bodies without impacts, they give special attention

to eutrophication and take into account the biological

quality.

Evaluation of likelihood of failing to meet theenvironmental objectives

After classifying pressures and impacts, we can assess the

likelihood of the Pinios failing to achieve good ecological

quality by 2015. The results are expressed as one of four

risk categories: high, medium, low and lack of data (Table

6). With these results, we can design a more rational

management plan and a more effective programme of

measures, where necessary. This classification should not

be a rigid methodological panacea, because each judge-

ment should be made cautiously and specifically for every

case.

Table 4 Habitat Modification Class

HMS HMC

0 Natural

0–2 Seminatural

3–8 Predominantly unmodified

9–20 Obviously modified

21–44 Significantly modified

4 45 Heavily modified

HMS, Habitat Modification Score; HMC, Habitat Modification Class.

Water and Environment Journal 23 (2009) 200–209 c� 2008 The Authors. Journal compilation c� 2008 CIWEM. 203

IMPRESS analysis applied in the Pinios river basinA. Ioannou et al.

Results and discussion

Pressures from pollution sources

The total emission, input loads produced within the Pinios

river basin and the EQS for irrigation and fish life are

calculated (Table 7). The inputs of all three pollutants are

higher than the quality standards for fish life. It is

important to note that the river has a nutrient retention

capacity, trapping part of the inputs in the sediment and

metabolising the remainder. It is possible to calculate the

necessary input load reduction in order to comply with

standards for fish life. These correspond to 36 553 kg BOD/

day, 218 877 kg N/day and 1523 kg P/day load reduction.

It is evident that with regard to BOD and nitrogen

inputs, livestock breeding is the most polluting

activity (Fig. 3). The urban point pollution sources

(untreated domestic wastewater) also significantly con-

tribute to organic pollution (20%) and are the most

important source of phosphorus inputs. Diffuse land-use

pressures are responsible for 17.5% of nitrogen inputs

and for 40% of phosphorus; thus, it is demonstrated that

agriculture is a very important activity with respect to

eutrophication in the river basin, with phosphorus being

the limiting nutrient. The WWTPs play an important role

in reducing pollution loads to the Pinios basin surface

waters, except phosphorus, as none of the WWTPs

include the tertiary treatment required to remove this

element.

Industry (largely food manufacturing and processing)

does not pose a serious threat to the river as it only

contributes a relatively small amount to the total pollu-

tant load according to the available data. Industry is,

however, concentrated in certain parts of the Pinios

catchment, and thus can result in serious localised pollu-

tion pressures. As livestock breeding appears to be the

most polluting activity, there is a certain amount of

uncertainty involved in predicting their environmental

impact due to lack of data concerning the location of

livestock farms and associated pasture land, their antipol-

lution measures (if any) and methods for the disposal of

pollutants into the environment.

Hydromorphological alteration pressures

The rarest features were wetland, open water, underwater

roots, braided channels and riverside vegetation. It is

evident that intensive agriculture seriously constrains

the extent of natural land use and riverside vegetation.

Furthermore, the extent of flood phenomena is modified

by the presence of embankments (Leyer 2004). Many

illegal direct water abstractions were present in 70% of

Table 6 Hierarchical categories (coloured accordingly) of the failure

probability meeting environmental objectives risk assessment (Castro

et al. 2005)

Impacts

Certain Probable Absent No data

Significant

pressures

Yes High Medium Low Medium

No High Medium Nonexistent Low

No data High Medium Low Not estimable

Table 5 Classification of water bodies in relation to the certainty of the apparent impacts also characterised by a specific shading (Castro et al. 2005)

Pollution pressures

Morphological alteration

pressures (Environment

Agency 2005)

If all the following statements are true:

Certain Mean biological quality

inferior to good

Nutrient timelines of

increasing concentration

Average values of chemical

parameters exceeding

standards for irrigation

Mean HMS 4 8

If at least two of the following statements are true:

Impacts Probable Mean biological quality

inferior to good

Nutrient timelines of

increasing concentration

Average values of chemical

parameters exceeding

standards for potable water

2oMean HMS � 8

If all the following statements are true:

Absent Mean biological quality

superior to good

Nutrient timelines stable or of

decreasing concentration

Average values of chemical

parameters inferior to

standards for fish life

Mean HMS � 2

Table 7 Comparison of emissions and inputs, with maximum permitted

input loads

Emissions Inputs

Irrigation

standards

Fish life

standards

BOD (kg/day) 245 811 58 870 185 976 22 317

Total N (kg/day) 1 468 296 263 586 390 550 44 709

Total P (kg/day) 13 652 3011 5207 1488

BOD, biological oxygen demand.

Water and Environment Journal 23 (2009) 200–209 c� 2008 The Authors. Journal compilation c� 2008 CIWEM.204

IMPRESS analysis applied in the Pinios river basin A. Ioannou et al.

the sites, and many impoundments and temporary dams

were also found that withhold the water so as to be

abstracted. Water impoundment is a serious pressure

mainly during the summer months (Shiao & Wu 2004)

when discharge is low. In many cases, zero flow was

observed, which is likely to increase pollutant concentra-

tions in the water and severely deplete available oxygen.

Identification of significant pressures

As stated previously, inputs for all three pollutants exceed

the maximum permitted loads for fish life, and hence we

can conclude that the pressures from pollution sources

are significant. Based on Corine Land Cover data, the

agricultural land use occupies nearly 50% of the area of

the entire river basin and so the hydromorphological

alteration pressures are also significant (see Table 5).

Impact assessment

It is evident that the most important factor resulting in

eutrophication is nitrate due to the increased use of

nitrogen fertilisers. Total phosphorus remained approxi-

mately constant, showing only small fluctuations and no

temporal trend. Ammonia shows a gradual and steady

decrease in concentration from 1989 to the present. This

corresponds to the opening of the WWTP at Larisa. The

increase in nitrate concentration is so large and its impact

so great that uncertainties regarding the minor impacts of

the other nutrients are unimportant (Fig. 4).

The mean values and standard deviations of some

chemical parameters – from the national monitoring net-

work – are calculated (Table 8). The location of each site is

depicted in Fig. 1. The mean dissolved oxygen concentra-

tions exceed the fish life limit, except at a single tributary

(Kalentzis station, 08.14.02), which is downstream of the

Karditsa WWTP. In the same station – as well as in two

others downstream of Larisa city (08.11.07 and 08.11.09)

– high values of COD occur probably for the same reason.

Nutrient concentrations are all quite elevated and above

the EQS for fish life (Trikala Prefectural Decision 4813/98

1998). Total phosphorus even surpasses the irrigation

standards at most stations.

In summary, impacts from excessive fertiliser use are

present at many points along the River Pinios and tribu-

taries and contribute to eutrophication while organic

pollution seems to be not as important. More detailed

data for the chemical quality of the River Pinios can be

found in various papers (Chatzichristidis et al. 1991;

Fytianos et al. 2002; Bellos et al. 2004; Bellos & Sawidis

40%

10% 9%

11%

1%

29%

Total P

17.5%1.3%

0.3%0.1%

0.3%

80.5%

Total NBOD

70%

2%

20%

8%

Urban pointUrban diffuseWWTP

IndustryLivestockDiffuse-agriculture

Fig. 3. BOD, total phosphorus (P) and total nitro-

gen (N) inputs that originate from each activity.

Years

0.20

Con

cent

ratio

n 0.15

0.10

0.05

0.00

1980

1981

1982

1983

1984

1985

1986

1987

1988

1989

1990

1991

1992

1993

1994

1995

1996

1997

1998

1999

2000

2001

Ammonia (mg/L) Total P (mg/L) NO3 (dg/L)

Fig. 4. Long term (1980–2001) fluctuations of

mean yearly concentration of nitrates, ammo-

nium ions and total phosphorus at the Ydatopyr-

gos Larisa site on the River Pinios.

Water and Environment Journal 23 (2009) 200–209 c� 2008 The Authors. Journal compilation c� 2008 CIWEM. 205

IMPRESS analysis applied in the Pinios river basinA. Ioannou et al.

2005). According to benthic macroinvertebrate field sur-

veys (Chatzinikolaou & Lazaridou 2007), 51% of the sites

are of medium biological quality, 29 and 9% are of bad

and very bad quality, respectively, and only 11% (six

stations) are of good quality (Fig. 5). Four of these six sites

are situated in the upper reaches of the river and on

tributaries. The mean score for all 56 sites is 2.36, which

corresponds to medium biological quality. The spatial

distribution of these sites does not, however, reflect the

quality of the whole of the river basin as they are situated

mostly in the main channel of the Pinios and in some

tributaries. The degree of accuracy resulting from this fact

is generally acceptable due to the preliminary nature of

the analysis, because there are no other data available and

because it is most probable that even if the distribution

was different, the quality range and proportion would be

the same because all tributaries discharge into the main

channel. Thus, we can say that the mean biological

quality for the whole of the Pinios river basin surface

waters is medium. On the basis of the data presented here,

plus the basic principle of the WFD of ‘one fail, all fail’

(European Union Council 2002), we can conclude that

the impacts from pollution pressures on the Pinios basin

are ‘certain’ (Castro et al. 2005; Table 5).

With respect to hydromorphological pressures, 56% of

the sites are seminatural while a large percentage are

predominantly unmodified (Fig. 6). The mean HM Score

for all sites is 4.1, which classifies the habitats of the main

channel of the Pinios as predominantly unmodified (Table

4). This is also likely to be the case for the entire river

basin because it is quite homogenous in terms of natural

characteristics and land use (predominantly agricultural).

Hydromorphological alterations in rivers such as the

Pinios that drain plains make the organic pollution

Table 8 Physicochemical parameters in the Pinios basin

Designated

uses

Dissolved

O2 mg/L

SO4� 2

mg/L

COD

mg/L

NO3�

mg/L

NO2�

mg/L

NH4+

mg/L

Nitrogen

Kjendahl

mg/L

P2O5

mg/L

Sampling

sites

Irrigation 4 3 o250 – o50 o0.5 o1.5 o2 o0.7

Potable water – o250 o30 o50 o0.5 o0.5 o2 o0.7

Fish life 4 6 – – o5 o0.01 o0.04 o1 o0.2

08.11.01 Mean 10.20 35.99 12.25 20.52 0.2298 0.10 1.376 0.56

Standard deviation 4.62 12.42 3.23 19.47 0.2224 0.11 0.385 0.21

08.11.03 Mean 6.49 25.99 21.25 7.22 0.2770 0.08 1.295 0.97

Standard deviation 4.90 3.41 6.74 3.75 0.1984 0.06 0.247 0.94

08.11.06 Mean 9.24 27.58 19.25 7.37 0.1920 0.10 1.578 0.99

Standard deviation 3.05 6.63 6.16 4.08 0.2343 0.06 0.242 0.69

08.11.07 Mean 9.08 30.11 22.63 7.24 0.1795 0.09 1.550 0.79

Standard deviation 3.45 5.30 10.61 4.40 0.2070 0.12 0.236 0.52

08.11.09 Mean 8.45 30.05 25.63 8.04 0.2033 0.13 1.550 0.88

Standard deviation 4.06 5.96 7.43 4.58 0.2320 0.10 0.268 0.74

08.11.11 Mean 10.81 20.30 14.63 6.30 0.1570 0.11 1.050 0.53

Standard deviation 2.69 8.50 2.91 4.07 0.1289 0.08 0.158 0.38

08.11.13 Mean 10.60 32.55 19.00 13.44 0.1443 0.13 1.075 0.30

Standard deviation 4.82 8.97 5.55 5.35 0.1823 0.12 0.043 0.21

08.12.02 Mean 10.64 26.80 17.57 10.02 0.0520 0.08 1.070 0.87

Standard deviation 1.76 5.92 5.37 2.64 0.0211 0.07 0.193 0.33

08.12.03 Mean 11.39 34.92 16.57 12.12 0.0547 0.15 0.954 0.87

Standard deviation 2.25 17.19 8.07 2.18 0.0403 0.17 0.159 0.43

08.13.01 Mean 9.43 39.01 21.50 10.43 0.1774 0.14 1.750 0.50

Standard deviation 5.10 9.50 4.36 5.34 0.2333 0.23 0.098 0.49

08.13.03 Mean 9.62 35.88 21.67 18.04 0.2760 0.27 1.530 0.42

Standard deviation 3.81 9.58 7.80 9.65 0.2188 0.39 0.652 0.22

08.14.02 Mean 8.11 29.94 29.75 5.74 0.2764 1.19 1.934 2.81

Standard deviation 5.35 12.23 15.78 3.85 0.3656 1.30 0.413 4.03

08.15.04 Mean 11.64 39.16 16.43 21.18 0.1926 0.27 1.053 0.20

Standard deviation 3.79 4.56 6.39 6.01 0.2239 0.40 0.029 0.20

Mean yearly concentration, standard deviation and classification according to the suitability of designated use based on environmental quality standards

contained in Greek national and prefectural legislation. If the range of a parameter (mean� s.d.) at a site is outside of one quality standard limit then the

cell is coloured with the failed use’s row colour. Bold values indicate that the parameter itself (and not only the range of the parameter) fails the limit for

the selected (according to the cell’s colour) use.

Water and Environment Journal 23 (2009) 200–209 c� 2008 The Authors. Journal compilation c� 2008 CIWEM.206

IMPRESS analysis applied in the Pinios river basin A. Ioannou et al.

impacts worse (Buffagni et al. 2002) and thus render their

biological communities more sensitive to possible distur-

bance (Gazzera et al. 1991). According to the previous

analysis (Table 5), the impacts from hydromorphological

alteration pressures are probable.

Evaluation of likelihood of failing to meet theenvironmental objectives

We can conclude that the risk of failing the environmen-

tal objectives for the entire river basin due to pollution

pressures is high (Table 6), whereas the risk of failure due

to hydromorphological alteration pressures is medium.

The measures that should be applied in each case can be

seen in Table 9. We suggest that measures are immediately

put in place to reduce pollution inputs and to reinforce the

river’s self-purification capability. In addition, a more in-

depth IMPRESS analysis should also be undertaken with

more detailed methodologies and with more extended

monitoring data. These data could come from operational

monitoring programmes (CIS Working Group 2.7: Mon-

itoring 2003) based on the results of the IMPRESS analysis.

A long-term programme of measures should also be ap-

plied that would have as its main goal to educate the

farmers in codes of sustainable agricultural practice.

As this is the first IMPRESS analysis undertaken on the

Pinios, it is based on already existing data and on approx-

imate environmental pressure quantification. Its depth

and its precision depend considerably on the availability

of data and methodologies. It does not use a statistically

robust methodology as it is highly based on expert judge-

ment – and because it was designed to suit the available

data. However, the results are directly comparable with

each other, provided that there is the same amount of

data available for each different analysis. The methodolo-

gical limitations derive from the limited data availability

with respect to the quantification of pollution loads, the

nonexistence or limited official monitoring networks and

from the fact that the hydrographic network has not yet

been separated into water bodies as required by the WFD.

The most serious problem is the limited environmental

pressure data used to undertake the IMPRESS analysis.

The methodology used was devised to utilise already

available data sets. Data deficiencies are observed in many

areas compared with other EU countries. The industry

census inventory is not complete and does not to include

all enterprises. The exact type of septic tank, as well as

their location and their proximity to watercourses is

unknown. Not all WWTPs provide a detailed index of the

pollution loads that each emits to the environment. The

antipolluting technologies (if any) used by livestock

breeding farms are not known, nor is the final destination

of their liquid and solid wastes. The amount of fertiliser

Table 9 Measures for risk management according to each risk category from Table 6 (Modified from Castro et al. 2005)

Impacts

Certain Probable Absent No data

Significant

pressures

Yes Immediate application of a

programme of measures

Long-term programme

of measures

Surveillance monitoring Operational monitoring

NoAdditional IMPRESS

analysis Operational

monitoring

Prevention of deterioration Surveillance monitoring

No

dataOperational monitoring

Surveillance monitoringImmediate additional IMPRESS

analysis

Biological water quality

29%

9%0% 11%

51%

High

Good

Moderate

Poor

Bad

Fig. 5. Biological quality at 56 sites on the River Pinios.

31%

9%3%

1%

56%

Seminatural

Modification class

Predominantly unmodified

Obviously modified

Significantly modified

Heavily modified

Fig. 6. Habitat Modification Class distribution at 402 sites along the main

channel of the River Pinios.

Water and Environment Journal 23 (2009) 200–209 c� 2008 The Authors. Journal compilation c� 2008 CIWEM. 207

IMPRESS analysis applied in the Pinios river basinA. Ioannou et al.

used in cultivated areas is not registered but is considered

certain that it usually exceeds the recommended limit.

Furthermore, GIS-based deterministic models should be

created for the estimation of diffuse pollution loads. In

order for this to become feasible many of the following data

deficiencies should be addressed: antipollution technolo-

gies and the exact location of livestock breeding farms;

aquifer height, soil types and their permeability; exact

amounts of fertiliser used; and the river’s self-purification

capacity. A presentation and comparison of models used in

other EU Member States can be found in De Paepe (2000).

Another very important deficiency is that Greece has

not yet developed a method for identifying the ecological

river status (Chatzinikolaou et al. 2008). The use of biota in

freshwater quality assessment is one of the most important

and innovative aspects of the WFD and should be a top

priority in Greece’s water management agenda, especially

when most EU countries already use biological assessment

methods (European Environment Agency 2003). Hydro-

morphological elements, which the WFD states that should

be used to define the borders of good and excellent

ecological status, are equally important to monitor as they

form the biota’s habitat. In the United Kingdom, for

example, there exists an extensive monitoring network

that includes an assessment of the hydromorphology of

numerous sites within each major river catchment. RHSs

using a standard protocol are thus carried out on a regular

basis in the United Kingdom (EA 2003).

The EQS set by European legislation should be adapted

to the Greek environment to reflect more accurately the

special conditions that affect ecological quality. Up to

now, relevant European legislation EQS were defined for

three uses: irrigation, drinking and fish life. The first two

refer to the quality required for anthropocentric uses and

not for the preservation of the ecosystem functions. The

third reflects conditions necessary for the survival of

certain fish species and not the general ecological condi-

tions under which the entire fluvial ecosystem functions

naturally. Greek catchments are marked by high spatial

differences in morphological, climatic, hydrographic, pet-

rographic and vegetative features, plus large variations in

the amount and type of pollution. Furthermore, river and

stream habitat, hydrochemical regime and biocommunity

structure show considerable spatial variability (Skouliki-

dis 2002). These characteristics indicate that a different

EQS should be defined for each river type that will reflect

general ecological conditions.

In conclusion, we suggest that the following im-

provement should be incorporated into the methodology

of subsequent IMPRESS analysis carried out in

Greece:

� Water bodies ought to be identified, categorised into

types and an IMPRESS analysis should be conducted for

each type. This would of course require monitoring data

for the entire river basin – something that is currently not

available in Greece. If these data were available, the

results of the IMPRESS analysis would be more easily

comprehensible, and could identify that part of the river

or stream at greatest risk and where operational monitor-

ing should be applied.

� The EQS should be updated and a model-based ap-

proach should be used for the quantification of diffuse

pressures as mentioned above.

� Finally, statistical methods should be used to assign

confidence scales in each category classification.

Although this first analysis involved a major degree of

uncertainty – something acceptable within the WFD –

and could be characterised as a risk screening, these

improvements are expected to improve the depth and

precision of the next series of IMPRESS analyses mark-

edly. It is anticipated that the assessment would then be

sufficiently detailed and specific to allow the classification

of the water body into the two key categories: at risk and

not at risk (CIS Working Group 2.1: IMPRESS 2003).

Acknowledgements

The field surveys of both RHS and water quality were

funded by a grant from the Greek Ministry of Education

for the project ‘HRAKLEITOS: Effect of management

practices on the water quality and ecology of rivers in

Greece’, Contract number: MIS 88740 (8/11/2002). The

authors are also grateful to the reviewers for their com-

ments that significantly improved the manuscript.

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