Module 2: Water Budget, Pressures and
Impacts, Significant Water Management Issues,
Monitoring, Characterization Report
Methodology for preparing hazard maps
and vulnerability assessment of karst
aquifers
Kaan Tunçok
Antalya, 2015
Groundwater from karst aquifers
most important drinking water resource in Europe:
• 35 % of the land-surface
• significant portion of the drinking water
Carbonate rock outcrops in Europe
Karst Areas
Conceptual Model of a Karst Aquifer
Conceptual Model of a Karst Aquifer
Characteristics of karst systems
 highly heterogeneous and anisotropic. Interpolation and extrapolation of field data is more
problematic
 dual porosity due to fractures and solutional voids (conduits) and frequently by a triple
porosity due to the additional presence of intergranular pores (matrix).
 Groundwater storage takes place in pores and fractures, while conduits act as drains.
contaminants can be transported very fast or stored for a very long time
 temporal variations of the groundwater table often reach several tens of metres.
 groundwater table is discontinuous and difficult to determine.
 large and hydraulically connected over long distances.
 karst springs often overlap and the flow paths proved by tracer tests often cross each
other.
Karst Systems
Karst Systems
• Models: predictions of groundwater levels
•Calibration: process of matching model
prediction to observed conditions
• Typically only done for groundwater levels
• In Karst it is critical that models are also calibrated to
• spring flows (regional)
• observable conduit velocities (tracer tests, observed
responses to storms or collapse, etc)
Karst Systems
Flow Through A Porous Media Aquifer
Recharge
Isotropic & Homogeneous
Discharge
Karst Systems
Flow Through A Karst Aquifer
Recharge
Heterogeneous - Anisotropic
Discharge
Cave Model
No-Cave Model
Quarry Area
MAX
1. how long does it take
until the contamination
reaches the target
2. To which level?
Pollution
2. at what concentration
level will the target be
contaminated
3. for how long will the
contamination last
1. When should
the pollution start
3. For how long?
Time
target
1. When should the pollution start
2. To which level?
Case a
B
Ao
Bo
3. For how long?
C
B
A
Case b
A
Time
COST Action 620
COST: Cooperation in Science and Technology
 an approach to “vulnerability and risk mapping for the protection of
carbonate (karst) aquifers”
 sustainable water use based on long-term protection of water resources.
 3 Working Groups (WG):
 WG1 developed an approach to the mapping of intrinsic vulnerability of
karst groundwater, based on sound scientific principles
 WG2 established a system to characterise the vulnerability of groundwater to
specific contaminants or groups of contaminants.
 WG3 worked on hazard and risk mapping.
WG1
 intrinsic vulnerability is a function of the geological, hydrogeological
and hydrological properties of a system
 by definition independent of the properties of specific contaminants.
 Main intrinsic factors, which decide on the vulnerability of groundwater to
contamination, are




overlying layers,
flow concentration,
precipitation regime and
properties of the aquifer
WG2
 specific vulnerability takes into account both the properties of the
system and those of the contaminants, such as;
 nitrates,
 bacteria,
 chlorinated solvents and heavy metals.
 Important processes for specific contaminant attenuation include;




cation exchange,
biodegradation,
precipitation,
filtration and decay.
WG3
 Hazards are activities and land-use practices that pose a threat to
groundwater, such as agriculture, tourism, traffic and industry.
 Risk maps consider the activities that present the “risk” that threatens
groundwater.
 They are obtained by synthesising the information presented on both
hazard and vulnerability maps.
Groundwater Vulnerability
 Intrinsic vulnerability of groundwater to contaminants takes into
account




geological,
hydrological and
hydrogeological characteristics of an area,
independent of the nature of the contaminants and contamination scenario.
 Specific vulnerability takes into account the properties of a particular
contaminant or group of contaminants in addition to the intrinsic
vulnerability of the area.
Groundwater Vulnerability
 Resource Vulnerability
 For resource protection the GW surface in the aquifer is the target
 Pathway:
 vertical passage through the layers above GW surface (unconfined)
 surface of the aquifer (confined)
 Source Vulnerability
 For source protection water in a well or spring is the target
 Pathway: mostly horizontal flow within the aquifer
Groundwater vulnerability
 related to source–pathway–receptor model of contamination
Groundwater vulnerability
 Combination of Vulnerability,
Hazard, and Consequence
contribute to overall Risk.
 Vulnerability evaluates
pathway
 Hazard evaluates source,
 Consequence evaluates cost
of losing resource at the
receptor
Groundwater vulnerability
 Specific vulnerability
assessments include
intrinsic properties as well
as transport properties of
specific contaminant(s).
 Intrinsic vulnerability
accounts only for
hydrogeological
characteristics,
independent of properties
of specific contaminants.
 Each contaminant or
group of contaminants
behaves differently in
different layers.
Intrinsic Vulnerability
 3 aspects to be considered:
 advective transport time from the origin to the target;
 physical attenuation, e.g. by dispersion, dilution and porosity effects;
 relative quantity of contaminants which can reach the target (a portion of the
contaminants may never reach the target but leave the catchment via surface
runoff).
 WG 1 developed a conceptual framework for vulnerability assessment
and mapping with special consideration of karst aquifers, the “European
Approach”
Specific Vulnerability
COST Action 620 also proposes an approach to Specific Vulnerability
Mapping, which combines two types of information:
 physical and chemical behaviour of contaminants (or groups of
contaminants).
 different for each contaminant, but common for all field applications.
 Information about physical and chemical properties of layers.
 different for each layer due to different layer combinations and particular
properties (tectonics, karstification etc.) for each monitoring point of the
assessed area
Vulnerability Assessments
Parameters b
Name and reference
Type
a
Examples
D
R
A
S
U
O
Index Methods
DRASTIC (Aller et al. 1987)
INV
Al-Hanbali and Kondoh (2008),
Draoui (2008), Liggett et al. (2006)
GOD (Foster 1987)
INV
Gogu et al. (2003), Neukum and
Hötzl (2007)
EPIK (Doerfliger et al. 1999)
INV
Vías et al. (2005), Neukum and
Hötzl (2007)
Aquifer Vulnerability Index (AVI) (Van Stempvoort et al. 1993)
INV
Wei (1998), Alberta Land
Resource Atlas of Alberta (2009)
SPV
LaMotte and Greene (2007),
Antonakos and Lambrakis (2007)
Statistical Methods
Logistic Regression (Helsel and Hirsch 1992)
Process Methods
Frind et al. (2006), Butscher and
Numerical Models (e.g., MODFLOW [US Geological Survey]) INV or SPV Huggenberger (2008)
a
INV = intrinsic vulnerability; SPV = specific vulnerability.
b
D = depth to w ater; R = recharge/infiltration; A = aquifer characteristics (material, conductivity, etc.); S = saturated zone characteristics (e.g., flow
patterns, layering, hydraulic gradient); U = unsaturated zone characteristics (material, hydraulic conductivity, soil moisture); O = other characteristics
(e.g., explicit level of confinement, karst features, permeable pathw ays).
Light blue: parameters included in a given method. White boxes: parameters are not included. Purple boxes: possible inclusion of parameters, based
on actual study.
Hazard Mapping
 7-step work plan
 starts from a definition and inventory of hazards
 leads to eventual production of hazard maps
 hazard maps must be simple if they are to serve as efficient tools in
planning and decision-making processes
 hazard is defined as a potential source of contamination resulting from
human activities taking place mainly at the land surface.
 hazard inventory starts from a differentiation between three main types of
land use: infrastructure, agricultural and industrial activities.
 to cover all various hazards that are considered relevant to groundwater
 to allow, mapping, evaluation and assessment of hazards in economically feasible
and practical manner
Risk Analysis
 “risk” is used for the likelihood of a specific adverse consequence.
 Following origin-pathway-target model risk depends on three elements:
 (1) hazards and their probability that a hazardous event occurs,
 (2) vulnerability of geological sequence and
 (3) consequences for groundwater.
Risk assessment split in two parts:
 Step 1, “risk estimation”, analyse potential intensity of relevant impact reaching
groundwater. deals with point (1) and (2).
 Step 2, “risk evaluation”, focuses on adverse consequences. depend on
the groundwater sensibility, like flow condition, and on the ecological and
economical value of the damages.
To separate different parts of risk assessment and to quantify their importance
 “risk intensity index (RII)”, “risk sensitivity index (RSI)” and “total risk index
(TRI)” were introduced.
Verification and Validation
 Independent of map-making process
 can range from; physically testing mapped area using techniques as
tracer tests, through to numerical models to ratify conceptual
understanding represented by the map
GW Vulnerability Mapping (Intrinsic)
 DRASTIC Method,
 best suited to regional assessments (1:50 000 and 1:100 000 scales) and has been applied in a large number of countries worldwide.
 Underestimates vulnerability of fractured aquifers
 Weighting system is not scientifically based
 GLA Method and its modification, PI-Method, used by the German states
 German State Geological Surveys (GLA) and the Federal Institute of Geosciences and Natural Resources (BGR) established a method for
assessing the protective function of the layers above the groundwater surface.
 does not address saturated zone within an aquifer.
 Does not take into account special properties of karst
 puts considerable emphasis on travel time as a measure of effectiveness of overlying layers to protect underlying groundwater
 Due to integration of infiltration via I factor, PI method suitable for all geological conditions.
 EPIK-Method used by Swiss authorities
 developed at University of Neuchatel in the early 1990’s to address risks posed to groundwater quality in the mountainous Alpine Karst of
Switzerland
 typically applied at a scale of 1:10,000
 Formula is not always applicable
 Not defined for all hydrogeologic settings
 Transformation of vulnerability classes into source protection zones is disputable
 COP-Method, “European Approach” in Karst areas
 Similar to PI-Method with the exception of Precip
 Parameters easy to acquire
 Choice of most appropriate method





data availability,
spatial data distribution,
scale of mapping,
purpose of the map and
hydrogeological setting.
DRASTIC Overview
 DRASTIC – guided by EPA
 Developed by EPA & National Water Well Assoc.
 Purpose
 Over large areas, identify regions where groundwater is more or less
susceptible to impact from pollution.
 Overview







Simplified GW vulnerability model
Qualitative
Produces a relative-risk scale
Applicable over large areas
Used as a screening tool
Results guide land development & resource protection
For small, specific sites, more detailed assessment needed
DRASTIC Method Assumptions
 Assumptions:
1.
2.
3.
4.
Contamination is introduced at the ground surface
Contamination is flushed into the groundwater by precipitation
Contamination has the mobility of water
Area being evaluated is 0.4km2 or larger
 If these assumptions are not met, then DRASTIC is not appropriate
DRASTIC Factors
Seven hydrogeologic factors used, form the acronym DRASTIC
D – Depth to Water
R – Net Recharge
A – Aquifer Media
S – Soil Media
T – Topography
I – Impact of Vadose Zone Media
C – Hydraulic Conductivity of Aquifer
Weights & Ratings
 Significance of each factor in contaminant transport varies
 Relative weight is assigned to each factor
 Scale of 1 to 5
 1 is least important factor
 5 is most important factor
Feature
Depth to Water
Net Recharge
Aquifer Media
Soil Media
Topography
Impact of Vadose Zone Media
Hydraulic Conductivity of Aquifer
Drastic
5
4
3
2
1
5
3
Agricultural
Drastic
5
4
3
5
3
4
2
 Each factor also has a Rating (1-10) applied according to a category or
range of values.
DRASTIC – The Equation
 Once ratings and weights have been applied, they are multiplied and
added
 DRASTIC equation:
DrDw + RrRw + ArAw + SrSw + TrTw + IrIw + CrCw = Pollution Potential
r = rating
w = weight
 Results are symbolized on a map overlaying study area
 Each physical parameter is
mapped spatially in GIS
 Each map is rated according to
its effect on vulnerability
 subsequent parameter maps
are combined to a final map
 DRASTIC scores are grouped
into vulnerability categories
ranging from high to low.
 Number of categories can vary.
GLA-Method and PI- Method
 GLA-Method (Hoelting (1995)) based on a point count system like DRASTIC model.
 Goldscheider (2002) developed GLA-method into PI-method (European COST 620)
 Unlike DRASTIC, GLA-method only takes unsaturated zone into consideration.
 Attenuation processes in the saturated zone are not included in the vulnerability
concept.
 Degree of vulnerability specified according to protective effectiveness of soil cover
and unsaturated zone.
 Parameters considered for assessment of overall protective effectiveness are:






Parameter 1: S- effective field capacity of the soil (rating for SeFC in mm down to 1m depth)
Parameter 2: W- percolation rate
Parameter 3: R- rock type
Parameter 4: T-thickness of soil and rock cover above the aquifer
Parameter 5: Q- bonus points for perched aquifer systems
Parameter 6: HP- bonus points for hydraulic pressure conditions (artesian conditions)
GLA-Method
Protective effectiveness (PT)
 PT = P1 + P2 + Q + HP
Where
 P1 - protective effectiveness of soil cover:
 P1 = S*W
 P2 - protective effectiveness of unsaturated zone (sediments or hard
rocks):
 P2 = W* (R1*T1 + R2*T2 + ........ + Rn*Tn).
GLA-Method
 Based on the German mapping approach, highest value assigned for
factor W, is 1.75 for a groundwater recharge of less than 100mm/a.
 A modified scale for the factor W was introduced which reflects low
amounts of groundwater recharge in many areas.
Groundwater
Recharge (mm/a)
Factor W
>400
0.75
>300 – 400
1.00
>200 – 300
1.25
>100 – 200
1.50
>50 – 100
1.75
>25 – 50
2.00
≤ 25
2.25
PI-method
 modification of GLA method, integrates protective cover (P) and
infiltration factor (I).
 Protective cover and infiltration factor are separately mapped as
individual maps and then combined to GW vulnerability map.
PI map
EPIK Method
 Development of the Epikarst,
 Effectiveness of the Protective cover
 Conditions of Infiltration and
 Development of the Karst network.
For each parameter a standard weighting coefficient is used.
Classification for each parameter and area is obtained by systematic
mapping for these parameters.
EPIK Method
EPIK Method
EPIK Method
Standard values for the EPIK parameters
Standard weighing coefficients for EPIK parameters
overall protection index F
Non-existent
High vulnerability
Medium Vul.
Low Vul.
European Approach
Four factors are considered:
 Overlying layers (O),
 Concentration of flow (C),
 Precipitation regime (P) and
 Karstic network development (K).
- O, C and K: internal characteristics of the system
- P: external stress applied to the system.
- Resource vulnerability mapping (top of saturated zone)
O, C and P taken into consideration
- Source vulnerability mapping (karst water supply such as a borehole or a spring)
K (in addition)
COP – Index = (C score) * (O score) * (P score)
European Approach
Overlying layers (O factor)
consist of up to four types of layers: topsoil, subsoil, non karst rock and
unsaturated karst rock.
 topsoil (layer 1)
 biologically active zone of weathering of the earth crust.
 composed of minerals, organic substance, water, air and living matter.
 Effective field capacity (eFC) to assess protective function
 subsoil (layer 2)
 granular, non-lithified material below the topsoil, for example Quaternary deposits
made of gravel, sand, silt and/or clay or alluvium.
 grain size distribution to evaluate protective function
 non karst rock (layer 3)
 ithified, non karstified rocks, for example sandstone, schist, shale, basalt
 unsaturated karst rock (layer 4)
 unsaturated (vadose) zone of the water bearing, karstified unit.
European Approach
O factor takes into account
 protective function of unsaturated zone and
 properties of the layers soil (OS – soil subfactor) and
 unsaturated zone ( OL- lithology subfactor).
Both are separately calculated and then added to obtain O factor:
 O = OS + OL
C Factor
In some karst areas, surface runoff is concentrated and channeled into swallow holes
Represents degree of concentration of flow water towards karstic conduits that are
directly connected with the saturated zone and thus indicate how the protection
capacity is reduced.
2 scenarios.
 Scenario 1: C is calculated based on




parameters distance to the swallow hole (dh),
distance to the sinking stream (ds) and
combined effects of slope and vegetation (SV):
C = dh * ds * sv
 Scenario 2 occurs in areas where aquifer is not recharged through a swallow hole. C
factor is calculated based
 surface features (sf) and slope (s) and
 combined effects of slope and vegetation (sv):
 C = sf * sv
P factor
Represents total quantity, frequency, duration of precipitation as well as intensity of
extreme events, which are considered to be chief influencing factors for the quantity
and rate of infiltration.
Obtained by summation of subfactors:
 quantity of precipitation (PQ) and intensity of precipitation (PI):
 P = PQ + PI
The calculation of the subfactor PI is based on the assumption that a higher rainfall
intensity results in an increased recharge and thus a reduced protection of the
groundwater resource.
The “mean annual intensity” or PI is calculated
 Mean annual intensity = mean annual precipitation (mm)
Mean number of rainy days
COP Method
 Intrinsic vulnerability treats all substances as having similar transport
behaviour as that of water,
 specific assessment additionally deals with differences between
particular contaminant behaviour and their specific interaction host rock.
 European approach for specific vulnerability.
 Based on
 principles of physical and chemical properties of layers and related processes
 properties of contaminants and related processes
European approach for specific vulnerability
Specific weighting factor
(S factor)
 an additional factor for
correcting the intrinsic
vulnerability values,
 layer conditions (potential
process in respect to
subsurface conditions)
 contaminant attenuation
capacities (potential process
of the particular
contaminant)
 contaminant factor concerns
the physical and chemical
contaminant properties.
 Each contaminant has its
own contaminant factor
Specific source and resource vulnerability maps
aim is
 to use criteria from intrinsic vulnerability assessment of an area, and
 to determine a positive specific attenuation index for each point in a catchment.
Specific weighting factor maps show spatial distribution of specific attenuation for individual
contaminant.
 S factor has to be linked to
 intrinsic overlying layers factor (O factor), in order to obtain groundwater resource specific
vulnerability maps.
 both the O factor and karst network factor (K factor), for compiling source specific vulnerability maps
 S factor modifies and upgrades the values of both intrinsic factors.
 Specific vulnerability assessment must be based on a set of intrinsic information.
 Specific vulnerability maps can be transformed into risk maps by the inclusion of
 hazards,
 probability of contaminant spills
 value of groundwater resources.
 Saturated karst layer may be very important for intrinsic vulnerability (high
advection, high dilution),
 it plays only a minor role for specific processes, due to their very low
contribution in saturated conduit flow.
 Specific maps for source protection are unlikely to differ significantly from
those for resource protection.
 Each specific contaminant requires an individual attenuation assessment,
using a standard 10-step procedure.
 3 main factors:
 contaminant factor (steps 1 and 2),
 layer factor (steps 3 to 9) and
 resulting specific weighting factor (step 10)
Specific vulnerability method
10-step plan for implementation of Specific vulnerability method
 Step 1
 Step 2
 Step 3
 Step 4
 Step 5
 Step 6
 Step 7
 Step 8
 Step 9
 Step 10
Choice of contaminant and related processes
Evaluation of contaminant process indices
Evaluation of layer process indices
Fitting of layer and contaminant process indices
Process weighting
Summation of processes
Consideration of layer thickness
Consideration of hydraulic properties
Summation of layers
Specific attenuation classes
Procedure
for specific
attenuation
evaluation
 Rating and Weighting are focused on the most important processes and
parameters use a qualitative judgement.
 Hydraulic property evaluation is also based on greatly simplified
considerations, with a discrete differentiation between diffuse and
preferential flow.
 Some of the input parameters are not stable in time.
 Use of validation tools is clearly envisaged.
 Computer modelling
 Artificial and natural tracing for simulating behaviour of specific contaminants.
Statistical methods
 Calculation of probability of a particular contaminant exceeding a certain
concentration.
 start with analysis and mapping of water quality from known sites (e.g.,
samples from wells or soil).
 integrate into linear regression models in which contaminant
concentration is related to a series of factors such as geology, well
depth, and/or land use.
 produce spatially distributed probabilities of exceedance, rather than a
categorized high, medium, and low ranking.
 may be used instead of indexing methods when there is specific interest
for a particular contaminant over a large area and sufficient data exists
on water quality in relation to the contaminant in question.
Process-based methods
 physically based and do not provide an
output of simple relative values (e.g.,
SAAT, SWAT, MODFLOW).
 Surface to Aquifer Advection Time
(SAAT) estimates average time
required for a particle of water to travel
from a point at ground to the aquifer
 Soil and Water Assessment Tool
(SWAT): USDA
 MODFLOW: USGS 3D finite-difference
groundwater model
 use deterministic approaches to
estimate time of travel, contaminant
concentrations, and duration of
contamination to quantify areas of high
and low vulnerability
Groundwater assessment requirements
Vulnerability
classification
Groundwater assessment requirements
Low
Groundwater contamination assessment report:
Requires a desk study to identify hazards and risk to groundwater or the
environment, and the need for any further action.
Low-moderate
Site investigation with monitoring:
Requires limited site investigation, groundwater monitoring, testing, and
delineation of flow system in addition to
desk study.
Moderately high
Detailed site investigation and monitoring:
Requires more detailed site investigation including ongoing monitoring and
protection design factors (e.g., natural attenuation, physical barriers) in addition
to requirements above.
High
Demonstrated remedial action plan:
Requires a remedial action plan that analyzes effectiveness of remediation in
achieving designated water quality criteria, and financial capacity of the
responsible party to enact the plan.
GENESIS project
 funded under the thematic area Environment (including Climate Change) of
the Seventh Framework Programme of the European Community for
research, technological development and demonstration activities (20072013).
 Total Cost: 9.170.600 €
 Duration: 60 months (start 1. April 2009)
 Consortium: 25 partners from 17 countries
 Project Coordinator: Prof. Bjørn Kløve, Norwegian Institute for Agricultural
and Environmental Research (Bioforsk), NORWAY
 www.thegenesisproject.eu
GENESIS project
 time frame of year 2015 for achieving a good status of groundwater
bodies is unrealistic mostly due to the considerably long time scales of
contaminant transport in groundwater systems.
 Consequently, the vulnerability assessment methods have to address
temporal and transient aspects of contaminant spreading and to
represent them in a quantitative manner in vulnerability indices
 In order to support groundwater managers and decision makers in
application of this physically-based approach to vulnerability assessment
a decision tree is proposed.
GENESIS project
 WFD and GWD aim at preservation and improvement of groundwater status.
 Groundwater bodies are classified as being or not being at risk of failing to meet
these objectives.
 Those at risk are subject to more precise risk assessments outlined in CIS No. 26
 concept of vulnerability is considered in the context of the source-pathway-receptor.
 within this conceptual framework vulnerability is related to the pathway part of the risk
assessment scheme.
 Assessment of vulnerability cannot be abstracted from characteristics of the
pressures on the groundwater body (CIS No. 3) and
 from characteristics of the receptors of impacts (CIS No. 18). Identification of the
source(s) and receptor(s) is thus an indispensable component of the problem
statement.
groundwater
vulnerability
problems and their
relevance to
GENESIS
case studies.
Specific Vulnerability
Work plan for hazard maps
 Step 1:
Definition and Inventory of Hazards
 Step 2:
Hazard Data Requirements
 Step 3:
Rating and Weighting of Hazards
 Step 4:
Graphical Interpretation
 Step 5:
Mapping Techniques
 Step 6:
Data Evaluation
 Step 7:
Production of Hazards Maps
Step 1: Hazard types and hazard classification
 emission of air pollution;
 discharge of waste water and non aqueous organic liquids;
 storage and disposal of solid waste;
 excavations in connection with mining, foundation and construction
work;
 distribution of fertilizers and pesticides.
Classification of hazards for GW
protection
Step 2:
Hazard Data Requirements
Each type of hazard requires information on the following:
 process or nature of activity (production, storage, etc.);
 type of harmful substances;
 amount of substances which can be released;
 age and status of installations and plants.
Collection of information on various hazards to be based on combined use of:
 extraction from topographic maps;
 evaluation of aerial photos;
 collection of data from archives and agencies;
 field surveying;
 direct inquiries with companies, etc.
Step 3: Rating and Weighting of Hazards
Necessary in the hazard assessment computation to arrive at a classification
of the hazards:
 establish a weighting system to allow comparison between different type of
hazards within a relative assessment scheme, and is suitable to formulate
possible groundwater protection zones or measures;
 establish a ranking procedure for hazards of same type, which fits above
mentioned criteria;
 develop an assessment scheme to determine likelihood that a release of
contaminant may take place in connection with a hazard;
 define a mathematical algorithm to calculate potential degree of
harmfulness for each hazard by considering weighting and ranking
coefficients as well as probability term to represent likelihood of a
contamination event.
Weighting Procedure
 The main criteria for weighting different hazards concern toxicity of
relevant substances associated with each type of hazards as well as
their properties regarding solubility and mobility.
 They determine the weighting coefficient or the “harmfulness of a hazard
to groundwater (H)”.
 Three parallel approaches were considered by WG3 to estimate
harmfulness of each hazard type.
 Approach 1, judge importance of each type of hazards by assigning figures between
0 and 10 according to their relevance in the respective test areas
 Approach 2, preliminary weighting factors were calculated with a formula, which is
used in connection with Italian vulnerability assessment scheme SINTACS.
 based on EU Directive on toxic sources of contamination.
 “contamination index” is calculated for each hazard by adding up potential
“environmental impacts caused by specific human activities”, which are considered
most important parameters to assess degree of harmfulness for groundwater.
 different environmental impacts are grouped according to EU classification of waste
hazards and water demand generated by human activities.
 environmental impact associated with each of these causes of environmental impact
is assigned a score ranging from 0 to 3 according to general experience on
environmental impact.
 Approach 3, six experts were asked to assign weights to all the hazards
appearing on the inventory list. They were asked to do so independently
from the previous approaches and only according to their experience
and the general toxicity. It was requested that values should be
distributed with a range from 0 (not harmful) to 100, indicating extreme
harmfulness.
 Finally, using the results obtained from each of the three approaches, a
weighted average was calculated for every hazard type
 If it is necessary to extend the list of hazards provided by Cost 620, it is
possible to follow the second approach
Ranking Procedure
 For a comparison between hazards of the same type, once again all the
different factors influencing the degree of harmfulness have to be
considered.
 ranking procedure should neither lead to a drastic minimization nor
excess overvaluing within a same category of hazards
 to maintain a fair balance with the average weighting values, it is
recommended that these weighting values should be changed only
slightly by multiplying them with a ranking factor between 0.8 and 1.2 in
order to indicate low or high amounts respectively of toxic substances
compared with the general average
Likelihood of groundwater contamination
 This coefficient provides an assessment of the probability for a
contamination event to occur.
 If no information on the above mentioned factors is available, then Rf=1.
 Zero, there is no risk of groundwater contamination,
 One, there are no reasons known to reduce the likelihood of an impact
to the groundwater
Calculation of the Hazard Index (HI)
 HI = H Qn Rf
 HI
H
 Qn
 Rf
hazard index,
weighting value of each hazard,
ranking factor (0.8 to 1.2) and
reduction factor.
 possible range of the hazard index HI from 0 to 120 scores.
 a subdivision of no more than five or six classes is recommended.
mapping procedure
Risk Assessment
Risk: possible contamination as a result from a hazardous event
Risk of contamination depends on:
 hazard posed by a potential polluting activity (equivalent to origin)
 intrinsic vulnerability of groundwater to contamination (equivalent to
pathway)
 potential consequences of a contamination event (target is GW)
Risk assessment: evaluation process for estimating potential impact of a
chemical, biological or physical agent on groundwater
Assessment has to take the following into account:
 likelihood of an impact
 intensity of a potential impact with which it affects GW (impact intensity)
 sensitivity of GW wrt impact (groundwater sensitivity)
Sustainable risk management
 Risk intensity assessment
 What can go wrong? Hazard identification and associated outcomes
 How likely is it to go wrong? Estimation of probability of these outcomes
 How far can hazardous impact reach the target? Estimation of possible impact
reduction
 Risk sensitivity assessment
 What would happen to the target if it does go wrong? Evaluation of the sensitivity
of target against the impact (consequence analysis)
 Is the risk acceptable and can it be reduced? Evaluation of damage wrt
environmental and economic value
 Risk management
 What decisions arise from risk assessment?
 What control measures are needed to minimize risk?
Risk Map
 Risk map: A method of summarising result total risk assessment with regard to
spatial distribution of risk.
 Risk intensity map:
 result of risk intensity assessment.
 combination of hazard map and vulnerability map.
 Risk sensitivity map:
 result of risk sensitivity assessment.
 depicts sensitivity of GW against a certain impact under consideration of economical and
ecological value of the resource.
 Risk map represents all aspects of assessment procedure.
Risk assessment
Risk intensity assessment
 high vulnerability and low risk index, if no significant pollutant loading
 high risk index value and low vulnerability, if pollutant loading is
exceptional or if possibility of bypassing in less vulnerable areas.
Risk intensity maps
Key Map Validation Tools
 Hydraulics and spring hydrographs

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

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BFW: base flow water,
RIW: rapid infiltration water,
RDIW: rapid delayed infiltration water
CIW: concentrated infiltration water
SIW: slow infiltration water
Natural Tracers can be grouped into:



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Ions and organic molecules in solution
Dissolved gases like radon and CO2
Environmental isotopes
Particles, including turbidity and bacteria/microorganisms
Do not provide information form precisely known injection points like artificial
tracers, can provide information on an aquifer wide basis
Artificial Tracers:
Three basic aspects have to be considered:
 Travel time of a contaminant from the origin to the target;
 Relative quantity of the contaminant that can reach the target;
 Attenuation processes decreasing the contaminant concentration.
Analytical and numerical modelling: data are needed in order to
proceed
 Geometrical and geological data for spatial discretisation of model
domain
 Parameters for characterising discretised zones for each simulated
process
 Stress-factors influencing groundwater quantity (infiltration, pumping and
re-injection rates) and groundwater quality (input/output of contaminant
fluxes)
 Historical data (distributed both spatially and through time) relating to
groundwater quantity (measured piezometric levels, water pressures,
spring discharges, hydrographs, tracer tests) and groundwater quality
(measured concentrations, chemographs, tracer tests).