doctoral thesis
NITRATE TRANSPORT IN CONDITIONS OF AUTOMORPH AND HYDROMORPHIC SOILS IN THE VUKA RIVER CATCHMENT AREA

Tamara Dadić (2016)
Josip Juraj Strossmayer University of Osijek
Faculty of Civil Engineering
Metadata
TitlePRONOS NITRATA U UVJETIMA AUTOMORFNIH I HIDROMORFNIH TALA NA PRIMJERU SLIVA RIJEKE VUKE
AuthorTamara Dadić
Mentor(s)Lidija Tadić
Abstract
Podzemne vode predstavljaju vrlo važan izvor vode, ali i osjetljiv sustav podložan različitim onečišćenjima. Među svim onečišćenjima koja mogu utjecati na kvalitetu podzemnih voda, posebno se ističu nitrati zbog svoje učestalosti i rasprostranjenosti. Osim toga, njihova prisutnost u podzemnim vodama izaziva značajan problem zbog negativnog utjecaja na ljudsko zdravlje zato što mogu uzrokovati pojavu različitih bolesti uslijed konzumiranja vode s povećanom koncentracijom nitrata, a u okolišu izazivaju eutrofikaciju. Nitrati nastaju procesima razlaganja dušika i njegovih spojeva, a u podzemnu vodu dospijevaju najčešće poljoprivrednim aktivnostima. Na pronos nitrata utječu brojni čimbenici kao što su vrsta i sastav tla, oborine, poljoprivredne aktivnosti, pokrov tla i sl. Kako bi se analizirao problem pronosa nitrata, odabran je sliv rijeke Vuke zbog velikog udjela poljoprivredne proizvodnje, ali i zbog toga što je dio sliva proglašen ranjvim područjem na onečišćenje nitratima prema NN 130/2012. Kako na slivnom području dominiraju automorfna i hidromorfna tla, analiza pronosa nitrata ograničena je na uvjete tih vrsta tala. Pronos nitrata je definiran procesima advekcije, disperzije, sorpcije i biodegradacije, a rađen je u sklopu računalnog paketa MT3DMS u GMS programskom okruženju. Kako su za proračun advekcijsko-disperzijske jednadžbe potrebne brzine i definiran tok strujanja podzemnih voda, prvo se pomoću MODFLOW paketa za cijelo područje sliva rijeke Vuke definirao numerički 3D model strujanja podzemnih voda. Model je rađen za stacionarne uvjete unutar vegetacijskog razdoblja 2006. godine. Na takvom modelu je rađena kalibracija, a zatim i parametarska analiza koja je pokazala da najveći utjecaj na strujanje podzemnih voda ima infiltracija, koja iznosi 17% ukupnih oborina palih na slivno područje, a zatim i hidraulička vodljivost slojeva, kao i provodljivost dna vodotoka na području sliva. Najmanji utjecaj od analiziranih parametara imaju evapotranspiracija, provodljivost dna kanala i provodljivost dna akumulacije koji se nalaze na promatranom slivnom području. Takav se model prebacio iz stacionarnog u nestacionarne uvjete tako što su modelu pridodani vodostaji i protoci svih rijeka i kanala koji se nalaze na slivnom području, kao i vrijednosti infiltracije i evapotranspiracije za razdoblje od 2006. do 2015. godine. Rezultati dobiveni takvim modelom za lipanj 2014. godine korišteni su kao ulaz za model pronosa nitrata zato što su tada započeta terenska mjerenja uz kanal Pumpa Orlovnjak koji je smješten na istom slivu. Mjerenja su obuhvatila određivanje razina podzemne vode i koncentracije nitrata pomoću plitkih pedoloških piezometara smještenih uz obale kanala. Dobivene koncentracije nitrata iz piezometara koji su smješteni na lijevoj obali kanala, odmah uz poljoprivredne parcele, su korištene kao neto ulaz nitrata u model. Modelu su još pridodane i početne vrijednosti nitrata izmjerene na nekoliko lokacija na slivu 2014. godine. Nakon kalibracije rađena je parametarska analiza i takvog modela koja je pokazala da najveći utjecaj imaju upravo početne koncentracije nitrata. Manji utjecaj na rezultate imaju ulazne neto koncentracije nitrata, poroznost i vrijednost konstante brzine reakcije prvog reda koja refletkira proces biodegradacije, odnosno u uvjetima saturiranih vodonosnika denitrifikacije. Posljednji je model rađen kako bi se utvrdila vrijednost konstante brzine reakcije prvog reda koja reflektira utjecaj denitrifikacije za uvjete vegetacije u melioracijskim kanalima u automorfnim i hidromorfnim tlima, a nastao je teleskopskom doradom mreže cijelog sliva rijeke Vuke kako bi obuhvatilo samo područje kanala na kojem su se provodila dvogodišnja terenska mjerenja. Provođenjem kalibracijskog procesa definirana je vrijednost analizirane konstante u iznosu od 0,018. Kako bi se utvrdila povezanost i utjecaj oborina i podzemne vode na koncentraciju nitrata, detaljno su analizirani rezultati dobiveni terenskim mjerenjima. Vrijednosti koncentracije nitrata zabilježene na lijevoj obali kanala, uz koju su poljoprivrdne parcele, su u 78,1% slučajeva bile veće nego one zabilježene u piezometrima na desnoj obali uz koju je prilazni put. Za tih 78,1% slučajeva, piezometri na desnoj obali kanala su pokazivali smanjenje od čak 62,5% u odnosu na lijevu obalu. Važno je napomenuti da najveća zabilježena koncentracija nitrata iznosi 43,34 mg/l. Kako se pokazala značajna razlika u dobivenim koncentracijama, posebno su analizirani nizovi koncentracija nitrata s lijeve, a posebo oni s desne strane kanala. Rađena je korelacija između oborina, nizova koncentracija nitrata i razina podzemnih voda za obje strane kanala. Osim samih nizova, uspoređivane su i njihove distribucije preko funkcije kopule. Najveća je korelacija dobivena između maksimalnih razina podzemnih voda i odgovarajućih koncentracija nitrata za desnu obalu kanala, s koeficijentom korelacije 0,706. Koristeći Normalnu kopulu, određeno je da vjerojatnost pojavljivanja koncentracije nitrata od 50 mg/l i veće u uvjetima melioracijskih kanala iznosi 10,29%.
Keywordsautomorph and hydromorphic soils nitrate concentrations groundwater River Vuka catchment area contaminant transport surface drainage canal correlation copula function
Parallel title (English)NITRATE TRANSPORT IN CONDITIONS OF AUTOMORPH AND HYDROMORPHIC SOILS IN THE VUKA RIVER CATCHMENT AREA
Committee MembersMarija Šperac (committee chairperson)
Lidija Tadić (committee member)
Neven Kuspilić (committee member)
GranterJosip Juraj Strossmayer University of Osijek
Faculty of Civil Engineering
PlaceOsijek
StateCroatia
Scientific field, discipline, subdisciplineTECHNICAL SCIENCES
Civil Engineering
Hydrotechnology
UDK626/627
APPLIED SCIENCES. MEDICINE. TECHNOLOGY
Hydraulic engineering and construction. Water (aquatic) structures
Study programme typeuniversity
Study levelpostgraduate
Study programmePostgraduate university study program in civil engineering
Academic title abbreviationdr. sc.
Genredoctoral thesis
Language Croatian
Defense date2016-10-11
Parallel abstract (English)
Groundwater represent important source of water, but also very sensitive system susceptible to different contaminant. Because of its impact on groundwater quality, frequency and distribution, nitrate contamination is especially standing out. Increased nitrate concentration in consuming water has negative effect on human health causing different deasises. In the environment nitrate can cause occurrence of eutrophication. Nitrates occur by decomposition of nitrogen and its compounds and their presence in groundwater, in the most part, is a result of agricultural activities. Numerous factors such as type and structure of soil, precipitations, agricultural activities and land cover have impact on nitrate fate and transport. In order of analysing problem of nitrate contamination and transport, River Vuka catchment is chosen because of significant part of agricultural fields in this area. Another reason is the fact that part of this catchment area is highly vulnerable to nitrate contamination according to document NN 130/2012. Entire catchment area is covered with automorph and hydromorphic soils, so nitrate fate and transport is restricted to conditions of these types of soil. Nitrate transport is defined with advection, dispersion, sorption and biodegradation and modeled with MT3DMS package in GMS surrounding. For calculation of advection-dispersion equation, velocities of the groundwater flow are required. For this, three dimensional numerical model of groundwater flow for entire catchment area is constructed within MODFLOW package. Model is constructed under stacionary conditions for vegetation period in year 2006. After model calibration, sensitivity analysis is performed. Results show that infiltration has the highest impact on model results. During calibration process, infiltration is determined in magnitude of 17% of total precipitations. Besides infiltration, hydraulic conductivity of soil layers and conductance of riverbed also have high impact on results. The parameters with lowest impact are rate of evapotranspiration, conductance of canals and acumulation bottoms. After calibration and sensitivity analysis, model was transformed in transient state by assignin values of water levels and observed flows for all rivers, canals and acumulation on catchment area as well as rate of evapotranspiration and infiltration for period between year 2006 and 2015. Result of groundwater flow for June 2006 was input parameter for nitrate transport model. That date was chosen because field observations near canal Pumpa Orlovnjak, wich is situated on catchment area, started at that time. During field observations, groundwater levels and nitrate concentrations were measured with shallow piezometers situated on banks of canal. Obtained nitrate concentrations from piezometers situated on the left bank of canal, were used as recharge concentration from agriculture fields on cathcment area. Besides recharge concentration, initial concentrations for year 2014 for entire observed area were incorporated in model. After simulation, calibration and sensitivity analysis were performed. Parameters with highest imapact are initial concentrations, recharge concentrations, porosity and first order constant reaction rate wich reflects influence of biodegradation, or in this case of confined aquifer, denitrification. Last model covered much smaller area were field observations were undertaken, and it was constructed from larger model which covers entire cathcment area. The purpose of this model was determination of first order constant reaction rate, or denitrification rate, for vegetation conditions in surface drainage canals in automorph and hydromorphic soils. During calibration proces, first order constant reaction rate is determined as 0.018. In order of determinating relationship between nitrate concentrations, groundwater levels and precipitations, results obtained by filed observations were analyzed in detail. Obtained nitrate concentrations from left bank of canal were greater in 78.1% cases than concentrations from piezometers situated on right bank which is next to road. In those 78.1% cases, reduction of nitrate concentration on the right side was 62.5%. The highest concentration measured during 2 year field observations is 43.34 mg/l. Because of great difference between obtained concentrations on the right and left bank of canal, two separate series were constructed and analysed. The correlation coefficients were obtained comparing data series of nitrate concentrations from right and lefts bank, groundwater level from the right and lefts bank and precipitations. Distributions of those data series were compared also using copula function. The highest correlation coefficient, 0.706, was obtained comparing highest groundwater levels and related nitrate concentrations on the right bank of canal. Using Normal copula function, probability of occurance nitrate concentration equal or higher than 50 mg/l in groundwater surrounding canals is calculated and it is 10.29%.
Parallel keywords (Croatian)automorfna i hidromorfna tla nitrati podzemne vode slivno područje rijeke Vuke pronos onečišćenja melioracijski kanal korelacija kopula
ExtentXIV, 157 listova : graf. i tabelarni prikazi : ilustr. (djelomice u bojama) ; 30 cm
Versionaccepted version
Resource typetext
Access conditionOpen access
Terms of usehttp://rightsstatements.org/vocab/InC/1.0/
Noteaccepted version
URN:NBNhttps://urn.nsk.hr/urn:nbn:hr:133:938842
CommitterVesna Zobundžija