?url_ver=Z39.88-2004&rft_val_fmt=info%3Aofi%2Ffmt%3Akev%3Amtx%3Adc&rft.relation=https%3A%2F%2Fpure.iiasa.ac.at%2Fid%2Feprint%2F4102%2F&rft.title=Water+Quality+Modeling+of+the+Nitra+River+(Slovakia)%3A+A+Comparison+of+Two+Models&rft.creator=Breithaupt%2C+S.A.&rft.creator=Somlyody%2C+L.&rft.description=IIASA's+Water+Resources+Project+deals+with+the+development+of+least-cost+water+quality+control+strategies+for+degraded+river+basins+in+Central+and+Eastern+Europe%2C+which+is+an+important+issue+due+to+the+lack+of+financial+resources+available+for+environmental+management.+The+Nitra+River+basin+in+Slovakia+serves+as+a+case+study+with+collaborative+research+by+IIASA%2C+the+Water+Research+Institute+(VUVH%2C+Bratislava)%2C+and+the+Vah+River+Basin+Authority+from+Slovakia.+The+Nitra+River+receives+large+loads+of+partially+or+untreated+wastewater+mostly+of+municipal+origin.+The+present+paper+compares+the+results+of+two+relatively+complex+water+quality+models+implemented+on+the+Nitra+River+(which+are+important+elements+of+developing+ambient+criteria+based+control+strategies)%3A+QUAL2E+and+RMA2%2F4q.+The+well-known+QUAL2E+is+a+result+of+systematic+developments+by+the+US+EPA+over+the+past+twenty+years+and+solves+the+steady-state+advection-diffusion+equation+for+temperature%2C+biochemical+oxygen+demand+(BOD)%2C+dissolved+oxygen+(DO)%2C+nitrogen+and+phosphorus+forms%2C+and+algae.+RMA2%2F4q+was+initially+developed+in+the+mid-1970s+for+the+US+Army+Corps+of+Engineers+and+has+been+consistently+maintained+and+extended+by+Resource+Management+Associates+and+researchers+at+the+University+of+California--Davis.+State+variables+and+reaction+terms+of+RMA4q+is+practically+identical+to+QUAL2E%2C+but+it+offers+more+details+in+computing+the+flow+and+physical+transport.+For+the+current+case%2C+this+model+was+used+to+solve+the+unsteady+one-dimensional+hydrodynamic+and+advection-diffusion+equations+for+temperature%2C+BOD%2C+and+DO.+Model+comparisons+and+calibration+results+showed+similar+BOD+decay+rates.+DO+was+overestimated+in+both+models+in+comparison+with+DO+observations+when+the+O'Connor-Dobbins+reaeration+method+was+used.+Fixed+reaeration+coefficients+gave+better+results%2C+with+QUAL2E+having+a+larger+value+than+for+RMA4q.+Sediment+oxygen+demand+was+included+in+the+QUAL2E+simulations+and+resulted+in+better+agreement+with+observed+data.+Additional+data+requirements+for+improved+understanding+of+water+quality+processes+in+the+Nitra+River+system+are+discussed.&rft.publisher=WP-94-110&rft.date=1994-11&rft.type=Monograph&rft.type=NonPeerReviewed&rft.format=text&rft.language=en&rft.identifier=https%3A%2F%2Fpure.iiasa.ac.at%2Fid%2Feprint%2F4102%2F1%2FWP-94-110.pdf&rft.identifier=++Breithaupt%2C+S.A.+%3Chttps%3A%2F%2Fpure.iiasa.ac.at%2Fview%2Fiiasa%2F1761.html%3E+%26+Somlyody%2C+L.+%3Chttps%3A%2F%2Fpure.iiasa.ac.at%2Fview%2Fiiasa%2F1584.html%3E++(1994).++Water+Quality+Modeling+of+the+Nitra+River+(Slovakia)%3A+A+Comparison+of+Two+Models.+++IIASA+Working+Paper.+IIASA%2C+Laxenburg%2C+Austria%3A+WP-94-110+++++