Hydrogeothermal (hydrogeological and geothermal) conditions of the Mura-Zala basin Slovenia and Hungary From Slovenia: Andrej Lapanje, Nina Rman (hydrogeology) Dusan Rajver (geothermy) From Hungary: Gyorgy Tóth, Judit Murati (hydrogeology and geothermy) Teodora Szocs (hydrogeochemistry and hydrogeology)

The numerical geothermal and hydrogeological models 1.There are large transboundary aquifers and geothermal reservoirs at the Slovenian-Hungarian border region 2.So far no serious cross-border effects have been detected, however common goals are to avoid future possible conflicts among users in the 2 countries (e.g. balneology and/or direct heat purposes)… 3.A harmonized, thermal aquifer management system is required. 4.The management system should be based on the best and most updated available geological, hydrogeological, hydrogeochemical, and geothermal information and expert knowledge 5.Best technology: Numerical models m Gravitational porous flow system Mixed gravitational and concvective karstic flow system Heat flow system Local stagnant or free convective system

Geothermal models

The geothermal gradient pattern based on Slovenian results: only steady state, and conduction Input parameters: Borehole Temperature Heat conductivities Surface temperature Heat flow densities Joint Slo-HU database and information base

Conductive and convective types of temperature logs from Slovenia Ljutomer-1: the deepest SLO borehole Benedikt-2: the large convection The effects of the last ice age Normal gradient Abnormal gradient caused by fluid convection

In Hungary: Large positive and negative anomalies at the 2000 m temperature map, explained by convections in the thermal karst system Nagylengyel and Zalaegerszeg Detailed and excellent literature studies at Bárszentmihályfa, Nagylengyel and Szombathely, but few exact temperature measurements were in standing wells. Additional high resolution temperature logs in the frame of the T-JAM project in geothermal different parts: Szombathely Spa-1 (765 m) Szombathely Spa-3 (665 m) Nagygörbő (1107 m) near Bakony regional recharge Kehidakustány (209 m) Hévíz regional discharge vicinity Zalaegerszeg (937 m) near convective part

Large regional flow model: focus on the thermal porous bodies (Mura (SLO) and Ujfalu/Zagyva (HU) formations (delta front, delta plain and alluvial plain sediments) But the system not „layer-cake” type, because tectonically deformed, and partly eroded: better connections at a few discharging zones: at Marcal, Zala and Drava valleys, and near Lake Hévíz

The flow model-construction for the regional transboundary groundwater body 2.Concept of the model 2.1Horizontal extent Horizontal extent of the Pannonian formations, plus surroundings, including some part of Austria and Croatia 2.2Vertical extent From the surface to the bottom (deeper, than m) of the Mura/Ujfalu/Zagyva Formations 2.3Hydrostratigraphic (HS) units in 3D Based on geological map (shallow unconfined) and 3D geology using regional seismic profiles and re-evaluated borehole data 2.4Model layers in 3D 6 modell layers. 1st unconfined; 2-6 confined; 6th: delta front; 2-5 delta plain, alluvial plain. Water works; 1st layer in SLO, 2nd layer in HU. Main thermal water complex: 6th layer 2.5Run type: steady state or transient Steady state on the 2000’nds productions and steady state for pre-exploitaed state 2.6Modeling software MODFLOW type (FDM model)

Depth of the bottom of the water works aquifers (HU) Depth of the bottom of the main thermal water bearing complex (HU and SLO) Modell layers in 3D

Hydraulic conductivities in the 1st model layer (based on the common, jointly prepared geological map) and 2D calibration process Major hydraulic conductivity units at the 6th model layer Local low conductivity unit west of Szombathely Better vertical conductivity units in the discharge zones Hydraulic properties of HS units

Recharge conditions: R= (1/a)×P 2 R: recharge mm/year P: multiannual average of yearly precipitation A: factor, depending of the uppermost 0,5-2 m of the soil forming rock types Precipitation mm/year Geo-units Recharge mm/year Boundary conditions

Discharge zones: drains everywhere, and rivers Production wells: The production wells were separated into four major groups: 1.Production of thermal waters from Ptuj, Mura and Lendava Formations in Slovenia 2.Production of thermal waters from Újfalu and Zagyva Formations in Hungary 3.Production of cold confined waters in Slovenia 4.Production of cold confined waters in Hungary The reason: investigate separate and common effects of the groups on the potential and depression level and budgets of different zones

Calibrations Cold confined HU GW table maps of alluvial plains in SLO Drava, Ptuj, Mura Thermal water hydraulic potential = environmental head values Disturbed (by nearby abstractions) hydraulic potentials: SLO cold confined and thermal water wells Semi-quantitive calibration of GW table around permanent creeks Comparative calibration of waters analyzed for 14 C and/or 18 O Constructed level maps reflects non-extracted state Budget of the mixing zones west from Hévíz

Additional water sampling from 12 SLO and 12 HU wells, for detailed hydrogeochemical and isotope analysis Origin of the samples: Present day or Riss-Würm interglacial precipitation Precipitation in the last Ice Age (Würm) Calibration: comparative study

Model outputs: potentials 1st layer: Shallow GW system 6th layer: Thermal groundwater system Pre-exploited Present productions

Model outputs: depressions Slovenian thermal water production only: caused depression in Hungary along the state border is: 4-5 m Hungarian thermal water production only: caused depression in Slovenia along the state border is: 1-1,5 m

Model outputs: depressions at different scenarios Present Scenario: all cold and thermal wells are active. Depressions at the close vicinities of the major production sites (Szombathely, Sárvár, Zalakaros, Moravske Toplice, Ptuj) are 8-16 m, and along the border 6-8 m Extreme Scenario: 5 times of present productions at the active thermal wells Depressions at the close vicinities of major production sites (Szombathely, Sárvár, Zalakaros, Moravske Toplice, Ptuj) are m, along the border m

Model outputs: budget of the TTGWB Mura-Zala HU SLO

Model outputs: depressions at different scenarios Lessons learnt from scenario analyses and proposal for management : According to the model results, approximately km zone around the major production sites should be delineated as reduced area for further developments of abstractions. Within these zones the maximum allowable abstraction rate should be determined („MI” concept in Hungarian 219/2004 Gov Decree) and/or some representative water level monitoring points (not too close to the center of production wells) should be constructed and by the helps of the transient model for determination of the critical level. And developments, out of these zones should be evaluated by the impact assessment by the help of the regional flow model

Other results or benefits from the model Better understanding the geothermal system; Approval the connections between the cold and thermal systems; Determination of the evaluation of geochemistry of the area; Quantification of the major recharges and discharges of the system Determination and approval the amount of the input from the porous thermal system to the thermal karst Opening possibilities for constructions better local groundwater model Paying attention that in the further regional model developments should be involved the Croatians partners

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