Vulnerability
mapping
of
Novljanska Žrnovnica karstic
spring catchment area
MedPartnership project
Terms of reference
Version 2
October 2012
Contents
Context of the study ............................................................................................................................. 3
Description of the pilot area ................................................................................................................ 3
Objectives of the study......................................................................................................................... 6
Scope of work - djelokrug .................................................................................................................... 7
Proposed deliverables and timeframe ............................................................................................... 9
Context of the study
Multiparameter methods of the natural (intrinsic) vulnerability mapping in hydrogeological
practice are used for fifteen years. Throughout this period, a number of methods were developed
and can be used with more or less success for karst aquifers. Karstic aquifers represents a large
portion of the aquifers in the Mediterranean region and determine of the most appropriate method
and /or the development of the new method can greatly contribute to the hydrogeologic practice in
this area. This study will use four known methods which are very widely used in the hydrogeologic
practice, and through the application of these methods on one pilot area (catchment of the
Novljanska Žrnovnica spring) will try to determine the most suitable for karst aquifers and / or
develop new method on the basis of used methods. These methods are: PI method, the COP method,
SINTACS method and the European Approach method (COST 620). By the mentioned four methods
natural vulnerability maps of the Novljanska Žrnovnica catchment area will be produced, and also,
using the experiences collected through the work with four used methods, the new method
appropriate for karst terrains will be developed. That method will be tested on the Novljanska
Žrnovnica spring cathment, too.
Description of the pilot area
Karst terrains in Croatia are mostly part of the regional structural - geological form of the
Dinarides, whose propagation can be traced from Slovenia on the northwest through the Croatia and
Bosnia and Herzegovina up to the territory of Montenegro. In the geological structure carbonate
rocks are dominated with full development of karst forms. Almost half of the Croatian territory,
including the Adriatic islands, belongs to the karst area of specific surface and ground morphological
characteristics. For Croatia, the karstic groundwater means nearly half of the total available amount
of water in the state.
The main characteristic of karst areas of the Dinarides are large basins rich with precipitation
(up to 4000 mm per year), low retention capacity of the karst underground, fast groundwater flow,
periodically flooded karst field, the appearance of big karst springs, springing and swallowing of the
water in the same catchment, high degree of intrinsic vulnerability of groundwater due to lack of
covering deposits and significant impacts of the seawater on the freshwater systems in the Adriatic
coastal area and islands. What does it mean in general? First, the huge total annual quantity of
water, which quickly drain to the recipient creating during the strong rainy periods very high
flooding, and during the summer dry periods runoff is significantly reduced due to the relatively low
retention capacity of the karst underground. Relation between karst spring discharges during the rain
and dry periods are one to several hundred, and some of the major karst springs remain completely
dry.
Novljanska Žrnovnica spring is located in the northern coastal area of the Croatian part of
Adriatic Sea. The capacity of the spring varies during the year from 0.5 m3/s during the summer
drought period to almost 15 m3/s during the autumn rainy period. In the catchment area there are,
except Novljanska Žrnovnica spring, more permanent and temporary springs in the more than 100
km long discharge zone along the coast. Some of them have significant discharge, but only
Novljanska Žrnovnica is captured for public water supply. The reason is that other springs are drying
up during summer time, or have big problems with salinization.
Novljanska Žrnovnica catchment area occupies about 1000 km2, which making it an one of
the largest catchments in the Adriatic basin in Croatia. The entire catchment is located on the
Croatian territory, and the catchment has not cross-border character. Catchment spreading is
northeast - southwest, as well as the spreading of the geological structures. On the north side of the
basin is the watershed of the Adriatic and the Danube basin. With complex hydrogeological
investigations the recharge areas of particular parts of the catchment has proved. Part of this
springing zone is fed from the northwestern part of the basin (Lič field), part is coming from the
mountain areas in the hinterland which stretches to the Gorski kotar area, and part from the Lika
area (sinkhole zone of the rivers Gacka and Lika), which was confirmed by a number of groundwater
flows tracing tests and hydrogeochemical investigations.
In the geological structure of this basin there are all of the elements characteristic for the
geological structure of the Dinarides, from predominantly clastic rocks of Palaeozoic age in the
anticline forms to a complete sequence of the Mesozoic age rock formations, which means the
thickness of the carbonate rocks of several thousand meters. Boundary conditions of the catchment
area of Novljanska Žrnovnica spring, groundwater flow direction and the occurrence of springs and
sinks are in the directly relation with the geological and structural conditions.
The most important water resources system in the Lika region, but also the Novljanska
Žrnovnica catchment area, are Lika and Gacka rivers, where is concentrated most of the water of that
water resource system. Under natural conditions, the water of these rivers were completely
swallowed in the swallow holes (ponor) in the Gacka and Lika poljes and as a groundwater drained to
coastal springs in the area from Novi Vinodolski to Karlobag, however, with the construction of HPP
Senj the natural conditions are substantially changed, especially during dry periods, because the
overflow of water during the rainy periods still drains into the natural sinks.
The Gacka river catchment area has a form of a "broad range" around the permanent spring
in the southeastern edge of Gacka field (polje). The main springs of that springing zone of the river
Gacka are Tonković spring, Majer spring and Klanac spring, while spring Pećina is separated and the
water from that spring flows into the Gacka river downstream of the spring zone. At these locations
more than 80% of the total amount of the Gacka river discharges. However, there are numerous
temporary springs in that zone which during the rainy periods gives a large amount of water. The
mean annual discharge of the spring zone is 11.2 m3/s. Near the town of Otočac the sinking zone
begins and the natural flow of the Gacka river splits into two branches, north and west. These flows
have ended up in natural sinks of Gacka river. Natural conditions have been modified during the
fifties with construction of HPP Senj, and today the sinkhole zone exceptionally drain overflow water
during rainy periods. West branch of Gacka ran toward the sinking zone, and ended on the biggest
Perinka swallow hole. The north branch of Gacka rarely flows downstream of Otočac. Very close to
the sinking zone of the north branch is reservoir Gusić where the water comes from the western
branch of the rivers Gacka and Lika by the hydrotechnical tunnel. From the Gusić reservoir the water
is transferring by hydrotechnical tunnel to the turbines of the HPP Senj, which are located on the
coast. Only during the rain period water discharges through the dam overflows to the natural sinks.
The Lika River catchment is located on the north side of Velebit mountain, which in that area
has a hydrogeological barrier function in the relation to the water runoff toward the sea. On the
hydrogeological aspect, the Lika river is significantly different from the river Gacka even though both
are part of the same water system, and after sinking enters in the aquifer, which is drained by
underground toward the springs along the coastal area from New Vinodolski to Karlobag. While the
Gacka river starts with the large karst springs, the Lika river starts with many small springs with a
relatively small catchment areas in the hinterland. The Lika river used to sink completely in the
natural conditions on numerous sinks in the swallow hole zone. With construction of HPP Senj, the
Lika river water is transported through the hydrotechnical tunnel in the Gacka river catchment area,
where is merged with the Gacka river waters and together transferred to the reservoir Gusić and to
the turbines on the coastal area. Only during the heavy rain periods when hydrotechnical tunnel
can't take all the Lika river water, and the capacity of reservoir Krušćica in the Lika river catchment
becomes insufficient water comes to the natural sinks of the Lika river. Sometimes neither sinks can't
"swallow" all the water and comes to flooding the entire area.
Thus, also the Lika river and the Gacka river waters sinks in the natural conditions in the
Gacka or Lika poljes. Groundwater tracing tests from swallowing zones of both rivers shows
conections to springs in the coastal area from Novi Vinodolski to Karlobag. In that coastal area
numerous springs were registered but the biggest discharge is on two points: Novljanska Žrnovnica
and Jurjevska Žrnovnica. The Novljanska Žrnovnica spring is certainly the most valuable and largest
spring in the coastal area of this large drainage area. The spring was captured for the water supply of
towns Crikvenica and Novi Vinodolski and surrounding villages. Important hydrogeological function
for the inflow of groundwater into the coastal area has a penetration of igneous rocks, which as a
local barrier system separates the part of groundwater flow towards the Novljanska Žrnovnica from
the groundwater flow towards Jurjevska Žrnovnica and other coastal springs between Senj and
Karlobag. Almost every bay in the coastal area has at least a temporary coastal springs, and
sometimes these springs and submarine springs are of larger dimensions.
Depending on the geological structure, tectonic activities in the geological history, level of
karstification of different parts of the catchment, but also different amounts of precipitation, terrain
slope and other parameters the intrinsic vulnerability of certain parts of the catchment is different.
For this purpose, to distinguish the most vulnerable areas of the catchment natural vulnerability map
using some GIS multiparameter method is a part of the hydrogeological research. There are several
different methods of making of natural vulnerability map in use in Europe and wider. Some of the
methods are "official" methods that were entered in the legislation of different countries in
determining the sanitary protection zones. However, although there are several different methods
none has exclusively developed for karst areas.
Objectives of the study
The Novljanska Žrnovnica catchment has chosen as one of the pilot areas because of the
diversity of geological structure, existence of the sinking zones, a large number of hydrogeological
investigations performed in the last thirty years, and very good knowledge of dynamics of
groundwater in the catchment. On the other hand, the Novljanska Žrnovnica spring is the only one
water supply spring in very long coastal zone, with no alternative for the public water supply for the
towns of Crikvenica and Novi Vinodolski. For the catchment area is planned to prepare maps of
natural vulnerability by using several methods and comparison of the results of these analyses. These
are the following methods: PI method, COP method, SINTACS method and the European Approach
method (COST 620). For each of the proposed methods it is necessary to divide the whole catchment
area into regular grid, or grid of rectangular cells. That cells must be a size of about 50 m depending
on the size of the basin, and the desired scale of data processing. Depending on the results of
analyses of different layers used in particular method, the new method will be developed on the
base of the best results that such layers has in used methods.
PI method was developed at the University of Karlsruhe and presented to the
hydrogeological public through the COST 620 project of the European Union. The basic concept of
this method is overlapping the two main layers: "P" - covering deposits and "I" - conditions of
infiltration. The "P" layer describes the protective function of covering sediments, or unsaturated
zone of the aquifer. The range of factors is from 1 to 5. Factor "P" = 1 indicates a very low level of
protection, and "P" = 5 very thick covering layers with a very good protective properties. Layer "I"
describes the amount of infiltration from the ground surface in the saturated zone of the aquifer. The
range of values is from 0 to 1. Value "I" = 0 indicates a zone where it is almost direct contact of the
ground surface with the saturated zone of the aquifer where the covering layers have no protective
function. When the value "I" = 1 the effectiveness of the protection of unsaturated zone of the
aquifer is 100%, and there is no passage of water infiltrated from the ground surface to the saturated
zone of the aquifer.
COP method was developed at the University of Malaga (Spain), also presented as one of
the methods through the COST 620 project of the European Union. The method is based on three
factors: the concentration of flow (C), the covering layers (O) and precipitation (P). The factor "O"
relating to the protection of the unsaturated zone of aquifer against potential contamination.
Displays the ability of the unsaturated zone to filter or exclude the possibility of groundwater
contamination. The factor "C" shows the situation on the ground surface that control the flow to the
sinking zones, or zones of high infiltration. The "C" factor values ranges from 0 to 1. The factor "P"
refers to the precipitation and its value is in the range 0.4 to 1. The influence of this factor is not so
much big as the factor "O". The final "COP" index is derived by multiplying these three factors.
The SINTACS method was developed in Italy, and is based on the weighted parametric
system derivated from the DRASTIC method. The method predicted using of seven parameters to
assess the natural vulnerability of the aquifer. These are: depth to groundwater (S), effective
infiltration depending on the types of sediments from the ground surface to the saturated zone of
the aquifer (I), self-purification factor of the unsaturated zone (N), type of covering layers (T),
hydrogeological characteristics of the aquifer (A), hydraulic conductivity (C) and morphological
features of the ground surface (S). Each of the parameters are weighted from 1 to 10 and with
overlying of these layers the natural (intrinsic) vulnerability map is obtained.
The forth method which will be used in this project is the European Approach method
developed within the COST 620 Action of the European Union. Four factors are considered within the
method: Overlying layers (O), Concentration of flow (C), Precipitation regime (P) and Karstic network
development (K). The factors "O", "C" and "K" represent the internal characteristics of the system,
while the "P" factor is an external stress applied to the system. For resource vulnerability mapping,
the factors "O", "C" and "P" should be taken into consideration, while the factor "K" should be
additionally taken into account for source vulnerability mapping (COST 620 Action Final report).
After mapping the natural vulnerability of the Novljanska Žrnovnica catchment using these
four methods the results and layers used in particular methods will be compared and critically
reviewed for the usage in the karst terrains. As a objective of this project the most applicable layers
will be used to develop new method which could be proposed for usage in the other karst areas
along the Mediterranean area. Also, because the multiparameter methods of mapping the natural
vulnerability are very similar to each other and they use similar layers, after making the basic layers
used in the preparation of this analysis it is possible to apply a different method and examine its
applicability.
Natural (intrinsic) vulnerability mapping methods can be used in spatial planning,
determining the sanitary protection zones of drinking water springs, the active approach of the
protection of aquifers, and also for the setting the priorities for remediation in some catchment area.
Scope of work
The scope of the work is framed by usage of four multiparameter methods for natural (intrinsic)
vulnerability map produce.
A series of activities relevant to achieving the above-mentioned objectives have been identified and
are listed below.
Activity 1 (PI METHOD MAP):
Collecting of the data needed to produce map of the natural vulnerability according to the PI
method: the layers "Covering deposits" and "Conditions of infiltration". For the purposes of the
production of the layer "Covering layers" the Basic geological map of Croatia, the Croatian
Hydropedological map, as well as numerous studies and projects developed in the catchment
area of Novljanska Žrnovnica will be used. For the purposes of the producing of the layer
"Conditions of infiltration" precipitation data from weather stations in the basin will be collected,
map of rainfall will be developed, and depending on the types of rocks from the ground surface
to the water table the conditions of infiltration will be determined.
Proposed output: Map of natural vulnerability of the Novljanska Žrnovnica catchment area
according to the PI method.
Proposed timeframe: 1,5 months.
Activity 2 (PI METHOD MAP):
Collecting of the data needed to produce maps of the natural vulnerability according to the COP
method: the layers "concentration of flow" (C), "covering deposits" (O) and "precipitation" (P).
For the purposes of the production of the layer "concentration of flow" the topographic map of
Croatia (S 1:25.000) will be used. For the purposes of the producing of the layer "covering
deposits" the Basic geological map of Croatia, the Croatian Hydropedological map, as well as
numerous studies and projects developed in the catchment area of Novljanska Žrnovnica will be
used. For the purposes of the producing of the layer "precipitation" precipitation data from
weather stations in the basin will be collected and the map of rainfall will be developed.
Proposed output: Map of natural vulnerability of the Novljanska Žrnovnica catchment area
according to the COP method.
Proposed timeframe: 1,5 months.
Activity 3 (SINTACS METHOD MAP):
Collecting of the data needed to produce maps of the natural vulnerability according to the
SINTACS method: depth to groundwater (S), effective infiltration depending on the types of
sediments from the ground surface to the saturated zone of the aquifer (I), selfpurification factor
of the unsaturated zone (N), type of covering layers (T), hydrogeological characteristics of the
aquifer (A), hydraulic conductivity (C) and morphological features of the ground surface (S). For
the purposes of the producing of the layers needed for the SINTACS method map, the Basic
geological map of Croatia, the Croatian Hydropedological map, as well as numerous studies and
projects developed in the catchment area of Novljanska Žrnovnica will be used.
Proposed output: Map of natural vulnerability of the Novljanska Žrnovnica catchment area
according to the SINTACS method.
Proposed timeframe: 1,5 months.
Activity 4 (EUROPEAN APPROACH METHOD MAP):
Collecting of the data needed to produce maps of the natural vulnerability according to the
European approach method: Overlying layers (O), Concentration of flow (C), Precipitation regime
(P) and Karstic network development (K). For the purposes of the producing of the layers needed
for vulnerability map, the Basic geological map of Croatia, the Croatian Hydropedological map, as
well as numerous studies and projects developed in the catchment area of Novljanska Žrnovnica
will be used.
Proposed output: Map of natural vulnerability of the Novljanska Žrnovnica catchment area
according to the EUROPEAN APPROACH method.
Proposed timeframe: 1,5 months.
Activity 5 (DEVELOPMENT OF THE NEW METHOD):
Comparing the experience of mapping natural vulnerability using the four used known methods
will be employed to develop a new method of the natural vulnerability mapping of karst aquifers.
With selected layers from used in the above methods, some new layers will be tried to introduce
and, finally, a new developed method will be tested on the catchment of the Novljanska
Žrnovnica spring.
Proposed output: The new natural vulnerability method with instructions. Map of natural
vulnerability of the Novljanska Žrnovnica catchment area according to the new developed
method.
Proposed timeframe: 2 months.
Activity 6 (FINAL REPORT):
The final report will contain a description of the used methods, as well as a detailed description
of the newly developed method through this project. Through the final report critically will be
shown a usability of these methods on the karst terrains. Attached will be the natural
vulnerability maps produced by the four used methods and, finally, the map was produced by a
newly developed method.
Proposed output: Final report.
Proposed timeframe: 4 months.
Proposed deliverables and timeframe
Preparing of vulnerability maps for the catchment area of Novljanska Žrnovnica with the
different methods (PI, COP, SINTACS, European Approach) will open the possibility to develop a new
method the most applicable for karst areas. For that method detailed instruction will be prepared.
That guideline could be used in some future vulnerability assessments in other karst catchments in
the Mediterranean area.
Proposed results of the project are:
1.
2.
3.
4.
5.
Natural (intrinsic) vulnerability map made by PI method
Natural (intrinsic) vulnerability map made by COP method
Natural (intrinsic) vulnerability map made by SINTACS method
Natural (intrinsic) vulnerability map made by the European Approach method
Development of new method the most applicable for karst aquifers with detail
instructions
6. Natural (intrinsic) vulnerability map made by the method developed throughout the
project
All deliverables will be submitted in paper format (2 copies for UNESCO) and in electronic format (CD
or DVD.
The study will need to be carried out within a 12 months period.
ANNEX
Proposed consortium from University of Zagreb, Faculty of Geotechnical Engineering:
- Prof.dr.sc. Ranko Biondić
- Dr.sc. Hrvoje Meaški
- Prof.emerit.dr.sc. Božidar Biondić
- Jelena Loborec, B.Sc.
Contracting Institution: University of Zagreb, Faculty of Geotechnical Engineering (GFV)
GFV will be responsible for coordinating the study and delivering the results.
Total budget for the study: 35 000 US$.
The budget covers all the costs of the project:
- The salary and the field trip costs of the experts involved,
- The administrative costs of GFV to manage the project.
Expected starting date of the project: January 2013
Expected ending date of the project: end of December 2013 (final report delivery)