Groundwater natural background levels and threshold definition in the Sofia Valley (Executive Environment Agency, Bulgaria).
R. Gorova, D. Deneva
Department of Water Monitoring and Department of Laboratory-Analytical activities, Executive Environment Agency at the Ministry of Environment and Water, 136"Tzar Boris III" blvd., 1618 Sofia, Bulgaria
SUMMARY
Here you summarise your case study. Here you summarise your case study. Here you summarise your case study.
1. INTRODUCTION
Sofia valley is a young neotectonic graben bounded on both sides by faults, is situated in central part of West Bulgaria. The big vertical movement created conditions of vast lake and river sedimentation during Neogene and Quaternary. The Quaternary and Neogene deposits are sands, clayey sands, pebbles, clays, and sandy clays in different alternations. Thermal mineral water were found by boreholes in some of the basement’s rocks at different parts of the basin.
Widespread petrography types predestined very intensive mining of sand, gravel and pebble in East part of the valley, began about 1960 with exploit depth up to about 15 m. The former quarry pits have been filled by groundwater and now many artificial lakes are available here.
Also drainages and irrigation channels are available and small reservoirs for irrigation as well.
Sofia – capital of Bulgaria is situated here. Sofia municipality has had 1.199.708 citizens - during 1998 and 1.210.806 citizens during 2005 (Nikolaeva, R et al., 2000). Many different human activities are developed in the area – Mining (an open mine for iron ores in north-East periphery – have been already closed) and quarrying, coke, refined petroleum, chemicals, pharmaceutical, rubber & plastic, machinery and equipment, fabricated metal products, food products, textiles products, wood products, etc. (Nikolaeva, R. et al., 2000).
Some waste landfills are situated here. Part of them are already closed. They were operated without landfill design as other Bulgarian landfills during 70-ies and 80-ies.
The steel Plant “Kremikovtzi” - a conglomerate of industries and technological activities (Dombalov 1998) is situated in the east part of the valley - with Pyrolytic treatment of coal, tailings pond, slag pond (have been operated more than 25 years) and Waste Water Treatment Plant (WWTP) etc. The above described human activities above described determined high pressure and impact above the groundwater.
Groundwater abstraction is very important for drinking water supply for the west part of Sofia valley and for some settlements in the east part. Groundwater are important for industrial and other supplies. (Nikolaeva, R. et al., 2000).
Two groundwater bodies are identified in Sofia valley – Quaternary and Neogene groundwater bodies. Groundwater bodies are hydraulically connected with water and terrestrial ecosystems.
Groundwater abstraction is about 48.9 millions m3 per year (Nikolaeva, R. et al., 2000) from both of groundwater bodies, about 40% are for drinking water supply. The exploitation resources have been determined: 37.8 millions m3 per year for the Quaternary GWB and – 41 millions m3 per year – for Neogene GWB (Nikolaeva, R. et al., 2000). We expect actual data from Danube River basin Directorate – Sofia department – on the basis of groundwater use permits have been issued.
2. CHARACTERISATION OF THE GROUNDWATER BODY (OR GROUP OF GROUNDWATER BODIES)
2.1 Physical and hydrogeological description 2.1.1 Geographical boundaries
Sofia valley is situated in the south part of the Iskar River Basin and this river is crossing the Balkan mountain chain. River Iskar is the longest Bulgarian river and it inflow in Danube. Iskar river basin is a sub-basin of the Danube River basin (Fig 1). Sofia valley is situated in Eastern Balkan Ecoregion(7)
Fig. 1 Map of Quaternary and Neogene groundwater bodies in Sofia valley
The common area of the valley is about 1200 km2, the size of the sedimentation basin during Neogene and Quaternary 1090 km2. And the Neogene GWB (Lozenetz geological formation) has size 973.4 km2.
The maximum length of the valley is 75 km (WNW-ESE) and the maximum width - is 20 km.
The altitude range in Sofia valley varies from 490 to 1065.9 m a.s.l. The main part is between 500 and 550 m a.s.l. The valley is surrounded by mountains which is the typical situation for the other kettles in the south part of Bulgaria
Fig. 2 Map of the topography
Fig. 3 Map of the soil cover
Land use is distributed in Sofia valleys as follows - Arable land - 57%, Urban areas - 27%, Woodland - 7%, Pastures - 8%, Others – 1%, Protected areas (~0.3%). Here we don’t include the draft NATURE 2000’ protected sites, because they have not been yet officially established.
Fig. 4 Map of the land use – acc. to CORINE LANDCOVER
2.1.2 Climate
The climate in Sofia valley is moderate continental with four seasons. Influence is available of the level above the sea, direction of the slopes (disposing to the sun shining) and urban (built) territories of the capital Sofia.
Fig. 5 Map with annual precipitation, air temperature and potential evapotranspiration
-5 0 5 10 15 20 25
T 0C
I II III IV V V I V II V III IX X XI XII
Tem perature
Fig. 6 Monthly distribution of the air temperature in Sofia (NIMH) meteorological station (period 1931-1970- (Kyuchukova, M., 1983))
0 20 40 60 80 100
R mm
I II III IV V VI VII VIII IX X XI XII
Precipitation
Fig. 7 Monthly distribution of the precipitation in Sofia (NIMH) rain gauge station (period 1931-1985- (Koleva, E.& Peneva, R., 1990))
2.1.3 Water balance
The average multi annual precipitation and potential evapotranspiration are shown on Fig.5.
The potential evapotranspiration was determined by Turc equation (1954)
2
9 .
0 ⎟
⎠
⎜ ⎞
⎝ + ⎛
=
L P Е P
E - is the potential evapotranspiration (mm year/ year ) P- is the mean potential precipitation (mm / year ).
The correlation parameter L is described as: L = 300 + 25T + 0.05 T3 and T is the mean air temperature (°C).
The potential evapotranspiration contour lines were obtained by use of grid with mean air temperatures and mean precipitation ( isotherms and isohyets). Calculations per every sell of the gr id with the Turc equation were made.
Estimation of groundwater recharge was made. Only part of the abstraction points are available in GIS now. The actual groundwater abstraction points with the abstraction quantities will be receive from the Danube River Basin Directorate – Sofia Department.
Fig. 8 Map with the annual groundwater recharge and abstraction point (abstraction points will be modified with actual data)
A mathematical model was created by V.Petrov and prof.I.Iotov for estimation of the water balance of Neogene groundwater body. (Petrov, V.). The balance component are shown in table 1.
Table 1 Annual average in mm of water balance components (P, ETP, groundwater recharge, Runoff (baseflow+shallow discharge)
Balance component Recharge,
m3/d
Discharge,
m3/d Balance
Boundary conditions III +67946 -38634 +29312
Rivers +481 -62370 -61889
Abstraction -88465 -88465
Total infiltration recharge +72923 +72923
Inflow from the Quaternary GWB +262791 -212087 +50704 The Neogene GWB natural water resource has been evaluated 152939 m3/d or 1770 l/s
The recharge exceeds the discharge with 29.9 l/s, which is 1.6 % from the total resources and practically is the inaccuracy of the modeling in the end of the last iteration.
The recharge from the rocks surrounding the valley is 29312 m3/d, which divided on the valley boundary contour (335 000 m) results to 1.01 (l/s)/km. From the sandstone surrounding rocks the recharge is 0.1-0.2 l/s, in areas with andesites it is varies 0.2-0.5 l/s, and is higher 1.5 – 1.8 l/s - from the carst basin (GWB) in North-West part of the valley.
The balance results show that the groundwater flow from the upper Quaternary GWB in vertical direction is preliminary descending. It exceeds the ascending vertical flow about 24% in the valleys central part.
2.1.4 Geology
Sofia basin is an young neotectonic asymmetric graben bounded on both sides by faults. The structures of the surrounding mountains are spreading under the Neogene deposits of Sofia valley as a rock basement. This rock basement is crossed by longtitudinal (100 – 130 0) and latitudinal faults (15 – 35 0), determined its block construction. Some of the blocks are raised others are submerged. The amplitudes varies. The big vertical movement created conditions of vast lake and river sedimentation during Neogene and Quaternary.
During Lower Meotian - Middle Pontian in the middle and the north part of Sofia basin rough drift and alluvial sediments were settled – this is Gnilyane geological formation ant it is not a subject of this report. Later – during Middle Pontian – deposition of lake’s sediments was occurred – clays, highly settled and consolidated. This is Novy Iskar geological formation and it is the lower aquitard of Neogene GWB.
During Upper Pontian and Lower Dacian the basin became shallow and lake-marsh conditions have become. The Novi Han Member (coal layers contained) was settled. And after that the Lozenets formation composed of very tick alluvial deposits were settled in active developing of river network conditions. The Lozenets geological formation is the lower GWB – so called Neogene GWB – subject of this report. Above it Quaternery sediments were deposited – the Quaternary GWB.
Lozenets formation – the Neogene GWB is formed from sandy layers, somewhere pebbles and gravels and sandy clays and clays.The number of aquifers is from three to 10, with a width 0.5 - 23 m, somewhere more. The total thickness of a waterbearing complex is from 38 up to 292 m (Petrov, V, 2004).
Quaternary deposits – the Quaternary GWB is formed by alluvial, drift, delluvial and mixed deposits are spreaded almost all over the basin. The petrographic description is pebbles with gravels and sandy filling, sands and clays. The total thickness is from 25 till 52 m ((Antonov, H., 1980).
Fig. 9 Map with the GWB in Sofia valleys and position of geological cross-sections
Fig. 10: Geological cross-section VII – VIII of the groundwater bodies – Quaternary and Neogene (Lozenetc formation) (location see Fig. 9)
2.1.5 Hydrogeology
The main groundwater bodies are above mentioned Neogene GWB (Lozenets formation) and Quaternary GWB.
Lozenets formation – the Neogene GWB is formed from sandy layers, somewhere pebbles and gravels and sandy clays and clays. It is a waterbearing complex with number of aquifers from 3 to 10, with a width 0.5 - 23 m, somewhere more. . The groundwater are unconfined and confined with different groundwater level or piezometric heads, because of complicated hydraulic connections between sandy, gravels and pebbles strata.The total thickness of a waterbearing complex is from 38 up to 292 m. (Petrov, V, 2004). The lower aquitard is Novy Iskar geological formation – composed by thick clays, sandy clays and some coal layers. Its thickness is 200 - 350 m.
Quaternary aquifer – Quaternary GWB. Alluvial, drift, delluvial and mixed deposits are spread almost all over the basin and covered the Neogene GWB. They are composed by pebbles, sands with clayey seams and somewhere boulders. Their total thickness vary from 25 till 52 m (Antonov, 1980).
Quaternary and Upper Neogene deposits in many areas have hydraulic connection and some autors consider them as one aquifer with leakage. But the unconfined upper part is affected by contamination from point and diffusive sources of pollution. The flow direction is radially from periphery (recharge area) to central part of the Sofia basin.
Because the pressure two groundwater bodies are separated - Quaternary and Neogene. Many of the available abstraction boreholes especially in East part in private yards of the people are shallow ones 15-20 m and they abstract about 200 l/s groundwater.
2.1.5.1 Delineation and type of groundwater body
Groundwater bodies in Bulgaria have been identified and delineated on the basis of geological and hydrogeological structures. Geological GIS vector map of Bulgaria in Scale 1:100 000 was used and hydrogeological raster map in Scale 1:200 000 as well. Also information from hard copy maps and reports in scale 1:25 000 (………). According to aquifer typology defined in WP2 (see e.g. D9 chapter 4) the types of GWBs are as follows:
Quaternary GWB – sands and gravels - fluviatile deposits of major streams ( incl. drift deposits of some small streams),
Neogene GWB - sands and gravels – Tertiary deposits
Fig. 11 Potentiometric map of the study area with – results from a mathematical model (potentiometric map of Neogene aquifer with indication of rivers is shown on Fig. 9)
The results of this groundwater mathematical modeling are only “rough resources assessment of upper neogene waterbearing complex”. As satisfactory for this model is accepted difference of 5-6 m between the model resulted and the real (multiannual mean values) groundwater levels (piezometric heads)” In some places inaccuracy is even 10 m. The model needs of more development and calibration in different parts – close to the inside (rivers) boundaries, close to the surrounding mountains rocks etc.
2.1.5.2 Hydrodynamics
Water balance for investigated Neogene groundwater body– recharge, leakage, discharge have been described in Table 2 (see 2.1.3.)
The Transmissivity determination had been made by different authors ( Iotov, I, et all., 1984) and (Petrov, V, 2004) but too much problems had been there. The boreholes in Sofia valley are with different depths – part of them are shallow ones and crossed only Quaternary, or even part of Quaternary deposits thickness. Others reached to Upper neogene deposits, but have different depths. The boreholes screens are situated also in different intervals ( expected to be permeable ones). In pumping tests only one borehole was used usually without observing boreholes. So in these conditions rough values for Transmissivity are determined. According to ( Iotov, I, et all., 1984) T = 90*(Q/s) and acc. to (Petrov, V, 2004) T = (85 - 95) *(Q/s), where
Q – is constant pumping rates (L/S) and s - steady drawdown (m).
On the basis of above described investigations the Transmissivity mapping was made for the East part of Sofia valley.
Maps with Transmissivity values areas in Sofia valley are available in scale 1: 50 000 (Valchanov, I, 1984). There are some areas with T = 1400-1600 m2/d in vicinity of Novy Iskar In North East part of West Sofia valley high permeable deposits are determined – T = 522 to 835 m2/d. Regions with low Transmissivity T = 30-50 m2/d are spread mainly in periphery areas, etc.
Table 2. Brief description of main hydraulic properties of the groundwater bodies GWB Thickness
(m)
Kh (m/d) T (m2/d) Average precipitation (mm/year)
Recharge (mm/year) Neogene GWB 38 – 292 <1 to 35 45 to 520 625 70 - 125 Quaternary GWB 25 – 52 36 to 300 300 to 2500 625 70 - 125
2.1.5.3 Hydrogeochemistry
Upper Neogene and Quaternary deposits are similar in their rock minerals content, because the sources of the sediments were surrounding mountains (Raykova, B., at all 1985). Mineralogical investigations were made on the Negene and Quaternary deposits (shallow part) shown content of kaolinite, hydro micaceous and montmorillonite minerals, which cristalline grids are built by Ca, Mg, K, Na, Si, Al, Fe , Mn. Manganese, gypsum and limy concretions are occurring in fine granule part of the deposits. During dissolution and ionic exchange of a.m. minerals mainly HCO3+, SO4 2-, Ca2+, Mg2+ and Na+ ions content occur in groundwater. A map with hydrochemical types of groundwater in scale 1:25000 was created for East Sofia valley and 2/3 of all the territory the groundwater are hydrocarbonate (hydrocarbonate-sulphate) – Calcium - Magnesium type. The zones with hydrocarbonate (hydrocarbonate-sulphate), Calcium - Sodium type are detected in West and East areas. Sodium ion dominated in industrial East part of capital Sofia and in NE directin from Sofia and in SW direction from Sofia. Higher sulphate concentration are available in a region between rivers Yaneshtica and Lesnovska.
2.1.5.4 Groundwater receptors
The dependent aquatic ecosystems are rivers, lakes and wetlands.
Fig. 12 Map with location of dependent aquatic and terrestrial ecosystems and protected areas acc. to Nature 2000.
Also protected areas are delimited for the sources for drinking water supply.
2.2 Identification of pressures 2.2.1 Groundwater abstraction
Locations of abstraction points are shown on fig.8. Groundwater abstraction is about 48.9 millions m3 per year (Nikolaeva, R. et al., 2000) from both of groundwater bodies, about 40%
are for drinking water supply. The exploitation resources have been determined: 37.8 millions m3 per year for the Quaternary GWB and – 41 millions m3 per year – for Neogene GWB (Nikolaeva, R. et al., 2000). We expect actual data from Danube River basin Directorate – Sofia department – on the basis of groundwater use permits have been issued – more than 500 permits.
Groundwater abstraction from 6 pebble, gravel and sand quarries in East Sofia valley is 2.6 Millions m3/ year (Andreev, A, 1998). Another big consumable of groundwater is a drainage in North parth of Sofia valley (Gnilyane – Novy Iskar) – abstraction about 3.2 Millions m3/ year.
2.2.2 Artificial recharge. There is no artificial recharge of groundwater in Sofia valley.
2.2.3 Pollution
2.2.3.1 Diffuse sourcesMain diffuse sources is agriculture and arable land.
2.2.3.2 Point sources
Many different human activities are developed in the area – Mining (an open mine for iron ores in north-East periphery – have been already closed) and quarrying, coke, refined petroleum, chemicals, pharmaceutical, rubber & plastic, machinery and equipment, fabricated metal products, food products, textiles products, wood products, etc. (Nikolaeva, R. et al., 2000).
Some waste landfills are situated in Sofia valley. Part of them are already closed. They were operated without landfill design as other Bulgarian landfills during 70-ies and 80-ies.
The steel Plant “Kremikovtzi” - a conglomerate of industries and technological activities (Dombalov 1998) is situated in the east part of the valley - with Pyrolytic treatment of coal, tailings pond, slag pond (have been operated more than 25 years) and Waste Water Treatment Plant (WWTP) etc. Contaminated soils with lead are occurs in surrounding of the steel Plant
“Kremikovtzi” – 2337.8 ha ( including 662.8 ha which exceeds maximum permeable values more than twice )
(WFD pollutants, priority substances, emerging pollutants, other pollutants of local interest).
Pollutant loading
WFD pollutants
Priority substances Emerging / other
Households and industry:
NH4, SO4, Pb, Cd, As
PAHs(Naphtalene),Phenols From pharmaceuticals Agriculture: NH4, NO3,
pesticides
NH4, P
Other: waste landfills
NH4, Cl, SO4
Phenols, Pb NH4,
detergents, Zn, Mn,Fe
Natural origin Mn,Fe
Groundwater impacts
NH4, SO4, Cl,
HS: PAHs (Naphtalene) NH4, PO4, Fe, Mn, Zn, detergents Lakes impacts
rivers and streams impacts
NH4, SO4 phenols Total
Petroleum
products, NO2, PO4, Fe, Mn,
Data are available from the reports for evaluation of damages of previous contaminations, reports of Environmental Impact assessment – some data from own groundwater monitoring are available as well
2.3 Conceptual model
In the basis of the mathematical model of V.Petrov 2 GWB were divided and a relative dividing layer between them. Recharge from the surrounding mountains is available and hydraulic connection with the rivers
1. Quaternary aquifer 2. Relative dividing layer between Q & N2
3. Lozenetska formation 4. Geological crossection
Fig. 2 Conceptual model of the groundwater body and dependent ecosystems
2.4 Existing natural background levels
2.4.1 National/regional method used for deriving natural background levels
If natural background levels have already been evaluated and establishedWe detect two investigations (reports) for the chemical composition of groundwater on the national level in Bulgaria the papers are in the National Geofund (Ministry of Environment and Water) – (Kehayov, T. , 1992) and (Shopova, Y., 1993)
The average values for the major elements (in mg/l) per every water bearing structure were given in tables and in the text and available data for trace elements as well in (in mkg/l) are given too in the text. Usually the heavy metals higher contents are situated around the bodies with ores, regions with mining activities, metallurgies and ores’ processing plants’ areas. In many cases there are assumed that higher concentration of Cu, Pb etc are caused by plants protection chemicals applied in agriculture ( the concentrations are below the drinking standards in more of the cases). Many concrete cases are given in the paper and concrete concentrations as well.
Results for GW bodies in Sofia valley (Kehayov, T. , 1992)
Table. 3. Mean values for some chemical components of groundwater in different aquifers in Sofia region
Aquifer TS Ca Mg Cl SO4 HCO3 NO3 H2SiO3 N2&Q 305±281 57±54 15±17 9±9 25±21 183±145 12±17 27±22 Upper Cretaceous
volcano- sedimentary complex
253±46 58±18 11±4 4±3 15±7 224±659 6±10 35±14
Lower Cretaceous - Jurasic Complex
336±113 95±36 9±9 11±9 14±9 337±152 12±17 27±22
Triassic complex 266±70 63±24 13±13 10±9 19±7 226±466 23±19
Results from (Shopova, Y., 1993). NBL for groundwater are determined on national level. The data are for time period 1965-1985 - 11 800 chemical analyses of groundwater have been used.
The samples are taken by springs, wells and little watercourses (creeks) – near to their sources.
The little streams are the main subject of investigation in the mountain regions, while the wells have been sampling in the plain regions. The springs are the predominant sources have been sampled in the hilly and middle high mountain regions. Data were processed on the basis of lithology facies assuming to the filtration geological media. The samples were divided in 11 groups consider to litolhogical (petrographic) description:
1. Delluvial sediments, clayey sands and clays with different geological age.
2. Marls, argilites (compact hard rock – dried clays), siltstones, etc – with Hauterivian, Barremian, Aptian and Albian geological ages (in ForeBalkan region, Mizia platform) and Upper Eocene in some of Tertiary grabbens (basins)
3. Quartzites, arcose sandstones, conglomerates, shales, shists etc – with Cambrian age (some structures are enumerated), Ordovician age (geological formation are enumerated); Silurian, Devonian, Permian age (some territories are enumerated); Also the were included shists of the Diabase-filitioide formation; quartzites and sandstones of the Lower Triassic; quartzites with Upper Cretaceous age and sericite - hlorite shists (Strandjza Mountain)
4. Flysh formations (sandstones, siltstones, clays, tuffs, andesites – with often changes in layers) – with different geological ages – from Lower Jurassic till Upper Cretaceous and Middle Eocene in different geologic-tectonic structures (they are enumerated here) and continental-molasse sediments – conglomerate, shale, coal-bearing, limestone-marl- sandstone (flysh – lyke) – Upper Eocene
5. Groundwater in carbonate rocks – limestones, doldmites of the Middle Triassic, Jurassic – Tithonian – ( the regions are enumerated here), Aptian (Urgonian limestones), Hauterivian and Barremian ages( North East elevated region), Maastrichtian ( the
regions are enumerated here), Upper Eocene( Chirpan region), Sarmatian (Varna region) etc; As well as the marbles in Rhodopi Mountains, South part of Pirin Mountain, Stargach and Slavyanka.
6. Alluvial deposits and alluvial – drift (prolluvial) deposits.
7. Loess and loess – like deposits and pebbles (gravels) layers under the loess.
8. Volcanic-sedimentary formations with Upper Cretaceous age – in Srednogorie structural zone; and Oligocene in Rodopi mountains and in South –West Bulgaria.
9. Acid volcanic and methamorphic rocks – granites, granodiorites, rhyolites and rhyodacites (the regions names are enumerated); gneisses, gneiss-shists in the Precambrian high-methamorphic complex.
10. Middle acid volcanic and and methamorphic rocks – diorites, dioritoporfirites, syenitodiorites, latites, trahites, trahiandesites, andesites etc. – ages and regions’ names are given there.
11. Ultrabasic and basic rocks – volcanic and metamorphic. Gabbro, gabbrodiorites, pyroxenites, peridotites; basalts, basaltandesites (Upper Paleozoic), serpentinites and amphibolites (Precambrian high-methamorphic complex).
There are excluded the sampling points connected to mineral (ores) deposits and their hydrothermal transformation zones, tectonic faults.
2.4.2 National/regional natural background levels of selected substances
Some results for groundwater NBL on national level:Table 3 Existing natural background levels
Parameter Values from-to
Mineralization from 100-200 mg/l to 800 to 1000 mg/l in the east part of Upper Tracian lowland from – because of the level of groundwater.
Ca from 5-10 mg/l to150 mg/l – in limestones in North
Bulgaria; in Yambol area and part of Upper Traccian graben because CaSO4.
Mg from 1-5 mg/l to 60 mg/l – in the loess region between rivers Isksr and Yantra
HCO3 from 10-20 mg/l to 600-700 mg/l – very limiteg regions in Yambol, area; some regions with 300-500 mg/l
SO4 from 5-10 mg/l till above 60 mg/l some regions
Cl from 15 to 25 mg/l – some regions – salty soils, near to the Black Sea
Cu to 5 mg/l
Zn from 1-2 ug/l to 80-150 ug/l in some regions of North Bulgaria
As from 0.1 ug/l to 20 ug/l – isolated regions SE from Sofia etc
Al from 1 to 45 ug/l – east part of Upper Traccian graben.
Mn from 1 to 8 ug/l
F from 100 ug/l to 300-400 ug/l – in some regions
Fe from 10 ug/l to 40-50 mg/l some regions
J till 4.5 mg/l – in parts of North Bulgaria
Pb to 3 ug/l
2.5 Review of impacts
Illustrate zone of influence, spatial distribution and temporal trends whenever appropriate.
2.5.1 Monitoring networks (groundwater and surface water)
Describe concepts and connection of networks, number and type of monitoring points, location, parameters, period, frequency. Compile data in Fig.14.
Different types groundwater monitoring networks are available for Sofia valley:
Part of the National groundwater monitoring network
National surface water monitoring network – points in Sofia valley.
Regional groundwater monitoring network for Sofia valley ( Chokoev, P, 1994 ). Data from National Geofund – data till 1998.
Own monitoring networks – from water use permits, IPPC reports, Environmental Impact Assessment Reports and local monitoring and Reports for evaluation of previous contamination – local monitoring networks – as points on industrial area of the steel plant “Kremikovtci” etc.
Fig.14 National and regional groundwater monitoring networks in Sofia valley
2.5.2 Effects of abstraction on groundwater quantity
Identify overabstracted zones and/or zones suffering severe water table decline. Consider impacts on recharge and major alterations to groundwater flow directions.
2.5.3 Effects of abstraction on groundwater quality
2.5.3.1 Salinisation2.5.3.2 Changes in redox conditions 2.5.3.3 Other geochemical processes
2.5.4 Effects of abstraction on dependent ecosystems
Evaluate impacts on discharge to dependent aquatic and terrestrial ecosystems. Estimate the induced decrease in surface water flow and water level in terrestrial ecosystems.
2.5.5 Effects of artificial recharge
Consider both groundwater quantity and quality issues and effects on dependent ecosystems
2.5.6 Effects of pollutant pressures on groundwater quality
Focus on pollutants identifying groundwater body(ies) as being at risk. Identify zone of influence of anthropogenic surface originated pollution. (fig. 1 D9, chapter 4)
Fig. 3 Cross-section with zone of influence indicated
Fig. 4 Map of pollution distribution with insert of example of time series from monitoring well
2.5.7 Effect of groundwater induced pollutant pressures on dependent ecosystems
Estimate groundwater induced loads (if possible relative to total surface water load in a baseflow situation)2.5.8 Pollutants selected for threshold methodology evaluation
Present a table or list with the pollutants selected for evaluation of threshold values, and indicate the pollutants, which are emphasised or focused on.
3. GROUNDWATER STATUS EVALUATION BY THRESHOLD VALUES 3.1 Application and evaluation of proposed threshold methodology
Data base from the National Geofund has been used for determination of NBL in Quaternary GWB - Quaternary fluviatile deposits of major streams in Sofia valley and Neogene (Upper Neogene) GWB - Tertiary deposits in Sofia valley. Data from wells and springs with approved geology age were statistically processed.
Preliminary data preselection have been made:
Samples from unknown depth boreholes are removed
Only data assumed to above mentioned groundwater bodies - Quaternary fluviatile deposits of major streams and Tertiary deposits in Sofia valley - have been processed.
Data have been removed - from Triassic limestones, Jurassic limestones - karst basin situated in in North-West part of Sofia valley, Upper Cretaceous - andesites, and mixed rocks - limestones,
tuffs, terrigenous in surrounding regions and in boreholes trough the hard rock basement of Sofia valley.
Data from hydrothermal aquifer ware removed.
Monitoring points with average nitrate concentration exceeding 10 mg/l were excluded too.
Natural Background Level were calculated for both of above describing groundwater bodies on the basis of 90 and 97.7 percentile.
Quaternary fluviatile deposits of major streams in Sofia valley Parameter Num.of
sites median P90 P10 P97.7 P2.3
Na 177 25 68.4 10 112.808 7
K 147 2 6 1 12 0.9358
Mg 205 19.2 34.6 10.28 53.616 5
Ca 204 64 113.688 32 174 21.338
Fe 106 0.2 1.9625 0.019 18.498 0.00332
Mn 57 0.33 1.352 0.0252 2.54816 0
HCO3 199 274.58 475.928 137.032 581.376 62.77
SO4 202 46 160.8 12 288.39 6.8115
Cl 206 17 49 8 144.85 6
NH4 47 0.15 2.64 0.0024 5.0811 0
NO2 55 0.04 1.084 0 10.3072 0
NO3 88 3 9 0 10 0
PO4 14 0.2775 1.8065 0.046 2.95001 0.0365 COD (Mn) 114 0.98 3.176 0.424 9.21465 0.23594
pH 203 7.35 7.9 7 8.3177 6.6646
Mineralization 203 479 831.148 258.2 1079.85 179.778 Ost105 196 369 605.75 208.5 949.372 153.153
Tertiary deposits in Sofia valley Parameter
Num.of
sites median P90 P10 P97.7 P2.3
Na 137 35 97.4 15.6 270 5.128
K 112 1.725 4 0.9 10.1705 0.59553
Mg 157 14 29 6 35.3003 1.294
Ca 155 53 104 24 153.203 10.626
Fe 106 0.135 0.5 1.9E-05 1.88588 0
Mn 86 0.165 0.725 0.00825 3.03015 0
HCO3 156 262.5 453.585 149 673.483 96.136 SO4 154 32.295 123.05 9 236.17 6.62975
Cl 156 14 44.75 6.55 70.4575 5
NH4 66 0.1 4 0 11.6535 0
NO2 49 0.05 0.792 0 2.0672 0
NO3 83 2.503 8.9 0.1 10 0
PO4 61 0.22 1.4 0.03 2.172 0.0038
COD (Mn) 118 0.955 3.226 0.3062 9.20289 0.14073
pH 156 7.7 8.3 7.2 8.887 6.9
Mineralization 156 438.21 794.098 269.65 1238.16 177.611
Ost105 151 329 607 220 1040.88 143.75
Selection of the Reference Quality Standarts
Quaternary
deposits Tertiary deposits
Parameter NBL 90 NBL 97.7 NBL 90 NBL 97.7 GW - EPT GW-CT DW SW- I SW- II SW- III
Na 68.4 112.808 97.4 270 50 100 200
K 6 12 4 10.1705
Mg 34.6 53.616 29 35.30028 80
Ca 113.688 174 104 153.20346 150
Fe 1.9625 18.49795 0.5 1.885875 0.05 0.2 0.2 0.5 1.5 5
Mn 1.352 2.54816 0.725 3.03015 0.02 0.05 0.05 0.1 0.3 0.8
HCO3 475.928 581.3755 453.59 673.483
SO4 160.8 288.39 123.05 236.16955 50 150 250 200 300 400
Cl 49 144.85 44.75 70.4575 30 100 250 200 300 400
NH4 2.64 5.0811 4 11.6535 0.12 1.2 0.5 0.133 2.667 6.667
NO2 1.084 10.30721 0.792 2.0672 0.025 0.125 0.5 0.007 0.147 0.220
NO3 9 10 8.9 10 10 30 50 25 50 100
PO4 1.8065 2.950005 1.4 2.172 0.1 1 0.5 0.2 1.0 2.0
COD (Mn) 3.176 9.21465 3.226 9.20289 5 10 30 40
pH 7.9 8.3177 8.3 8.887
6.5 -
9.5 6.5-8.5 6.0-8.5 6.0-9.0
Mineralization 831.148 1079.85 794.1 1238.1606
Ost105 605.75 949.3725 607 1040.875 500 1000 730 1050 1600 GW - EPT - Groundwater Ecological Threshold values (Bulgarian REGULATION No. 1 of 7 July 2000
on the Exploration, Use and Protection of Groundwater) GW-CT - Groundwater contamination Threshold values (Regulation N-1)
DW - Drinking Water Standards (Regulation No. 9 of 16 March 2001 on the Quality of Water Intended for Drinking and Domestic Purposes)
SW- I surface water 1-st category - suitable for Drinking Water supply (Standards for surface water) SW- II surface water 2- nd category - suitable for Irrigation supply (Standards for surface water)
SW- III surface water 3- nd category - suitable for some industrial supplies (Standards for surface water)
Reference values
Quaternary fluviatile deposits Tertiary deposits Parameter NBL90 NBL97.7 NBL90 NBL97.7 RV
Na 68.4 112.808 97.4 270 100
K 6 12 4 10.1705
Mg 34.6 53.616 29 35.30028 80
Ca 113.688 174 104 153.20346 150
Fe 1.9625 18.49795 0.5 1.885875 0.2 Mn 1.352 2.54816 0.725 3.03015 0.05 HCO3 475.928 581.3755 453.59 673.483 SO4 160.8 288.39 123.05 236.16955 150
Cl 49 144.85 44.75 70.4575 100
NH4 2.64 5.0811 4 11.6535 1.2
NO2 1.084 10.30721 0.792 2.0672 0.125
NO3 9 10 8.9 10 30
PO4 1.8065 2.950005 1.4 2.172 1
COD (Mn) 3.176 9.21465 3.226 9.20289 5 pH 7.9 8.3177 8.3 8.887 6.5 - 9.5 Mineralization 831.148 1079.85 794.1 1238.1606 Ost105 605.75 949.3725 607 1040.875 1000
Three cases for have been analysed:
1st – NBL<REF: then according to proposed methodology, TV=(REF+NBL)/2.
2nd – NBL<REF/3: then TV=2×NBL.
3rd – NBL>REF: then, TV=NBL.
Quaternary fluviatile deposits of major streams in Sofia valley Parameter NBL90 RV Case N TV90 NBL97.7 RV Case N TV97.7
Na 68.4 100 1 84.2 112.808 100 3 112.808
K 6 12
Mg 34.6 80 1 57.3 53.616 80 1 66.808
Ca 113.688 150 1 131.844 174 150 3 174
Fe 1.9625 0.2 3 1.9625 18.498 0.2 3 18.49795 Mn 1.352 0.05 3 1.352 2.54816 0.05 3 2.54816
HCO3 475.928 581.376
SO4 160.8 150 3 160.8 288.39 150 3 288.39
Cl 49 100 1 74.5 144.85 100 3 144.85
NH4 2.64 1.2 3 2.64 5.0811 1.2 3 5.0811
NO2 1.084 0.125 3 1.084 10.3072 0.125 3 10.30721
NO3 9 30 2 18 10 30 1 20
PO4 1.8065 1 3 1.8065 2.95001 1 3 2.950005
COD (Mn) 3.176 5 1 4.088 9.21465 5 3 9.21465
pH 7.9
6.5 -
9.5 1 8.3177
6.5 -
9.5 1 Mineralization 831.148 1079.85 Ost105 605.75 1000 1 802.875 949.372 1000 1 974.6863 Tertiary deposits in Sofia valley Parameter NBL90 RV Case
N TV90 NBL97.7 RV Case N TV97.7
Na 97.4 100 1 98.7 270 100 3 270
K 4 10.1705
Mg 29 80 1 54.5 35.3003 80 1 57.65014
Ca 104 150 1 127 153.203 150 3 153.2035
Fe 0.5 0.2 3 0.5 1.88588 0.2 3 1.885875
Mn 0.725 0.05 3 0.725 3.03015 0.05 3 3.03015
HCO3 453.585 673.483
SO4 123.05 150 1 136.525 236.17 150 3 236.1696 Cl 44.75 100 1 72.375 70.4575 100 1 85.22875
NH4 0.725 1.2 3 0.725 11.6535 1.2 3 11.6535
NO2 0.792 0.125 3 0.792 2.0672 0.125 3 2.0672
NO3 8.9 30 2 17.8 10 30 1 20
PO4 1.4 1 3 1.4 2.172 1 3 2.172
COD (Mn) 3.226 5 1 4.113 9.20289 5 3 9.20289
pH 8.3
6.5 -
9.5 1 8.887
6.5 -
9.5 1 4.4435 Mineralization 794.0975 1238.16 Ost105 607 1000 1 803.5 1040.88 1000 3 1040.875
The NBL 90 is more suitable for the Sofia valley region for derivation of threshold values – shown in the table
bellow.
Quaternary fluviatile deposits of major streams Tertiary deposits in Sofia valley
Parameter NBL90 RV
Case
N TV90 NBL90 RV Case N TV90
Na 68.4 100 1 84.2 97.4 100 1 98.7
K 6 4
Mg 34.6 80 1 57.3 29 80 1 54.5
Ca 113.688 150 1 131.844 104 150 1 127
Fe 1.9625 0.2 3 1.9625 0.5 0.2 3 0.5
Mn 1.352 0.05 3 1.352 0.725 0.05 3 0.725
HCO3 475.928 453.585
SO4 160.8 150 3 160.8 123.05 150 1 136.525
Cl 49 100 1 74.5 44.75 100 1 72.375
NH4 2.64 1.2 3 2.64 0.725 1.2 3 0.725
NO2 1.084 0.125 3 1.084 0.792 0.125 3 0.792
NO3 9 30 2 18 8.9 30 2 17.8
PO4 1.8065 1 3 1.8065 1.4 1 3 1.4
COD (Mn) 3.176 5 1 4.088 3.226 5 1 4.113
pH 7.9 6.5 -
9.5 1 8.3 6.5 -
9.5 1 Mineralization 831.148 794.098 Ost105 605.75 1000 1 802.875 607 1000 1 803.5 4. Conclusions
Groundwater thresholds values for Quaternary fluviatile deposits of major streams and for Tertiary deposits in Sofia valley are determined for receptor groundwater itself and for magnesium, calcium, COD (Mn) were used Bulgarian Drinking water standards.
The 90% percentiles were used for Natural Background Levels derivation.
High Natural Background Levels of total Iron and Manganese were derived in both of groundwater bodies. In all available historical investigations that problem emphasized and both of elements have natural origins – from the mineralogical rock components in the region. In North-East region of Sofia valley an old Iron mine is available and part of the ores contain Manganese minerals. Also Manganese concretions have been detected in tertiary sands deposits of the valley.
High levels of ammonia, nitrites and phosphates are connected with organic matters decay processes.
4. REFERENCES
1. Alipieva E., Nedjalkova A., Iliev E. (1985) Report of hydrogeological investigations on East Sofia basin, Report, Sofia, Bulgaria, EЕA.
2. Andreev A, Ananiev B, (1998 - 1999) , Annual reports from groundwater level monitoring around quarries with groundwater level lowering, Reports, Sofia, Bulgaria, EЕA.
3. Antonov H., Danchev D., (1980) Groundwater in Republic of Bulgaria, Sofia, Bulgaria 4. Dombalov I, Pelovski J, (1998) Report of Environmental Impact Assessment of Steel Plant “Kremikovtzi., Sofia, Bulgaria, MOEW
5. Grifin M, Steeds J., (1998) Determination of previous contamination and rehabilitation programme of Steel Plant “Kremikovtzi, WS Atkins International Ltd., Sofia, Bulgaria, MOEW
6. Jotov I, Ananiev B, (1998), Design of groundwater monitoring system of groundwater table around quarries with groundwater level lowering, Report, Sofia, Bulgaria, MOEW 7. Kostakieva E, (1999) Report of Environmental Impact Assessment of “Design for landfill redevelopment and rehabilitation of waste landfill Dolni Bogrov” Report, Sofia, Bulgaria, MOEW
8. Nechev B, Tzanov T., (1997) Report of Environmental Impact Assessment of the quarries. Report, Sofia, Bulgaria, MOEW
9. Pogidaev V., Stojanov I. (1998), Report of hydrogeological investigations around landfill Dolny Bogrov. Report, Sofia, Bulgaria, Sofia Municipality
10. Pogidaev V., Stojanov I. (1998), Drilling of additional monitoring boreholes and hydrogeological investigations around landfill Dolny Bogrov. Report, Sofia, Bulgaria, Sofia Municipality
11. Rajkova B, (1967) Study on chemical composition of groundwater in East Sofia basin, Bulgarian academy of Science, National Institute of Hydrology and Meteorology, V.11, Sofia, Bulgaria
12. Regulation N-1 about Investigation, use and protection of groundwater ( to a Water act), the Official Gazette, n. 57/2000.
13. Mladenov, A, 1996, Annual report for “Development of groundwater monitoring in Bulgaria. Multilayers system with fresh and mineral thermal groundwater in Sofia depression (geological-tectonic structure). Implementation of the working plan on regional monitoring of the groundwater in Sofia depression., National Geofund, V 0467
14. Chokoev, P, 1994, Report on “Development of groundwater monitoring in Bulgaria.
Multilayers system with fresh and mineral thermal groundwater in Sofia depression (geological-tectonic structure). Summarizing and interpretation of data from the region had been investigated, with rough assessment of the resources., National Geofund, V 0429
15. Chokoev, P, 1995, Report on “Development of groundwater monitoring in Bulgaria.
Multilayers system with fresh and mineral thermal groundwater in Sofia depression (geological-tectonic structure). Implementation of the working plan on regional monitoring of the groundwater in Sofia depression., National Geofund, V 0506
16. Andreev, A, 1998 Groundwater monitoring in Sofia geological basin. Implementation of the working plan, National Geofund, V 0444
17. Ananieva, M., 1997, Annual report on “Development of groundwater monitoring in Bulgaria. Multilayers system with fresh and mineral thermal groundwater in Sofia depression (geological-tectonic structure). Regional monitoring of groundwater in Sofia depression., National Geofund, V 0479
18. Hydrogeological maps 1:25 000 and reports and other materials in Scale 1:25000 for the East Sofia field and for the West Sofia Field – Ecological Kadastre in Executive Environment Agency.
19. Valchanov, I., et all, 1984 Hydrogeological investigatigations and creating the system for optimal groundwater use and protection (Determination and analysing of the resent status of groundwater in West Sofia valley) volume 1.
20. Raykova, B. et all, 1985, Evaluation of the quality composition of groundwater in the East Sofia valley for drinking and irrigation supply. Assessment of the regime of infiltration recharge of groundwater. , volume I, Ecological Cadastre of the Executive Environment Agency.
21. Kehayov, T. , 1992, Report: “Chemical composition of the fresh groundwater in Bulgaria”
1992, Dr. T. 349 p., Bulgarian language, and maps are available (hardcopy maps)., National Geofund
22. Shopova, Y., 1993 “Assessment of the natural hydro-chemical background of the concentration of chemical compounds in Bulgarian groundwater”, with hardcopy maps
CONTENTS
SUMMARY _______________________________________________________________________1 1. INTRODUCTION_______________________________________________________________1
2. CHARACTERISATION OF THE GROUNDWATER BODY (OR GROUP OF
GROUNDWATER BODIES) ________________________________________________________2 2.1 Physical and hydrogeological description _____________________________________ 2 2.1.1 Geographical boundaries _______________________________________________ 2 2.1.2 Climate_____________________________________________________________ 4 2.1.3 Water balance _______________________________________________________ 5 2.1.4 Geology ____________________________________________________________ 7 2.1.5 Hydrogeology _______________________________________________________ 8 2.1.5.1 Delineation and type of groundwater body ______________________________ 8 2.1.5.2 Hydrodynamics ___________________________________________________ 9 2.1.5.3 Hydrogeochemistry _______________________________________________ 10 2.1.5.4 Groundwater receptors ____________________________________________ 10 2.2 Identification of pressures ________________________________________________ 10 2.2.1 Groundwater abstraction ______________________________________________ 10 2.2.2 Artificial recharge ___________________________________________________ 11 2.2.3 Pollution___________________________________________________________ 11
2.2.3.1 Diffuse sources __________________________________________________ 11 2.2.3.2 Point sources ____________________________________________________ 11 2.3 Conceptual model_______________________________________________________ 12 2.4 Existing natural background levels _________________________________________ 12 2.4.1 National/regional method used for deriving natural background levels __________ 12 2.4.2 National/regional natural background levels of selected substances _Fejl! Bogmærke er ikke defineret.
2.5 Review of impacts ______________________________________________________ 15 2.5.1 Monitoring networks (groundwater and surface water)_______________________ 15 2.5.2 Effects of abstraction on groundwater quantity _____________________________ 16 2.5.3 Effects of abstraction on groundwater quality ______________________________ 16 2.5.3.1 Salinisation _____________________________________________________ 16 2.5.3.2 Changes in redox conditions ________________________________________ 16 2.5.3.3 Other geochemical processes _______________________________________ 16 2.5.4 Effects of abstraction on dependent ecosystems ____________________________ 16 2.5.5 Effects of artificial recharge____________________________________________ 16 2.5.6 Effects of pollutant pressures on groundwater quality________________________ 16 2.5.7 Effect of groundwater induced pollutant pressures on dependent ecosystems _____ 16 2.5.8 Pollutants selected for threshold methodology evaluation_____________________ 16 3. GROUNDWATER STATUS EVALUATION BY THRESHOLD VALUES___________16 3.1 Application and evaluation of proposed threshold methodology ___________________ 16 3.2 Results and compliance testing?____________________________________________ 16 4. CONCLUSIONS___________________________ FEJL! BOGMÆRKE ER IKKE DEFINERET.
5. REFERENCES ________________________________________________________________21
List of Tables
Table 1 Annual average in mm of water balance components (P, ETP, groundwater recharge, Runoff (baseflow+shallow discharge) ...Fejl! Bogmærke er ikke defineret.
Table 2 Main hydraulic properties of the groundwater body(ies)Fejl! Bogmærke er ikke defineret.
Table 3 Existing natural background levels ...Fejl! Bogmærke er ikke defineret.
Table 4 Information about monitoring networks ... 15
List of Figures
Fig. 1 Map of the groundwater body (or group of groundwater bodies)... 2 Fig. 2 Geological cross-section of the groundwater body...Fejl! Bogmærke er ikke defineret.
Fig. 3 Potentiometric map of the study area with indication of rivers and main groundwater flow directions ... 9 Fig. 4 Characterization of groundwater hydrochemical evolution along flowpath (if possible
redox boundaries, recharge - throughflow-discharge zones)Fejl! Bogmærke er ikke defineret.
Fig. 5 Map with location of dependent aquatic and terrestrial ecosystems and protected areas. 10 Fig. 6 Map of pressures ...Fejl! Bogmærke er ikke defineret.
Fig. 7 Conceptual model of the groundwater body and dependent ecosystems... 12 Fig. 8 Cross-section with zone of influence indicated ... 16 Fig. 9 Map of pollution distribution with insert of example of time series from monitoring well ... 16
