Simulating runoff, erosion, and phosphorus transport from a field with the ICECREAM model
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Journal Title
Journal ISSN
Volume Title
Insinööritieteiden korkeakoulu |
Master's thesis
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Author
Date
2021-12-13
Department
Major/Subject
Mcode
Degree programme
Master's Programme in Water and Environmental Engineering (WAT)
Language
en
Pages
71 + 8
Series
Abstract
Over 60 % of the agricultural fields in southern and western Finland are clayey. Because of the hydrometeorological conditions under a humid climate and a high water retention capacity of clay most of these fields need artificial drainage for proper cultivation measures and crop growth. In the region, over 70 % of the field area is subsurface drained, in the whole of Finland over 60 %. Because of the small particle size of clay soils, erosion and leaching of solids and particulate phosphorus is a threat to the quality of the receiving water bodies. In Finland, the majority of the human-induced phosphorus load to the Baltic Sea traces from agriculture. For the last few decades, the fields have been overfertilized. The objective was to evaluate ICECREAM, an agricultural management system model using field data collected during long-term campaign in Siuntio. The GĂ„rdskulla field section is typical for southern Finland: a relatively flat, subsurface drained clay soil. The dataset consisted of field hydrology data and solids and nutrient load measurements from a period of over 10 years, during which there was a transition from grain crop cultivation to permanent grass. The ICECREAM database covers all Finnish watersheds, and comparison of the modeling results to the measurements provided information on the model capacity to estimate the effects of land management practices and climate on the hydrological and water quality processes in soil. The ICECREAM model reproduced the observed relative change in phosphorus fractions: When changing from grain crop to permanent grass, the share of dis-solved phosphorus of the total phosphorus load increased, and the share of particulate phosphorus decreased. However, the model significantly overestimated the total absolute phosphorus load, and annual field runoff, which caused biases in the simulated water balance.Ăver 60 % av Ă„krarna i södra och vĂ€stra Finland Ă€r lera. PĂ„ grund av de hydrometeorologiska förhĂ„llandena i ett fuktigt klimat och lermarkers förmĂ„ga att binda vatten, krĂ€ver de flesta av dessa Ă„krar konstgjord drĂ€nering för anstĂ€ndiga odlingsresultat. Ăver 70 % av Ă„kermarken i omrĂ„det Ă€r tĂ€ckdikad. Förutom via ytavrinning transporteras sediment och fosfor via tĂ€ckdiken Ă€ven pĂ„ relativt svaga sluttningar. Eftersom lera har en vĂ€ldigt liten partikelstorlek Ă€r erosion och utlakning av sediment och fosfor ur jordbruksmark betydliga problem för kvaliteten av mottagande ytvatten. Av den fosforbelastning i Ăstersjön som orsakas av mĂ€nniskan i Finland Ă€r merparten frĂ„n jordbruket. Fosforbalansen i finsk jordbruksmark har lĂ€nge varit positiv pĂ„ grund av omĂ„ttlig gödning av Ă„krarna. Data insamlad frĂ„n GĂ„rdskullas forskningsomrĂ„de tillĂ€mpades för utvĂ€rdering av ICECREAM, en modell för hydrologi och Ă€mnestransport. Ă keravsnittet i GĂ„rdskulla Ă€r en för södra Finland typisk, relativt svagt sluttande tĂ€ckdikad lerjord. Det omfattande materialet bestĂ„r av data över fĂ€lthydrologin och mĂ€tningar av nĂ€ringsĂ€mnes- och sedimentkoncentrationer i avrinningsvatten samlad under en 10 Ă„rs period. Under perioden skedde en Ă€ndring i produktionsriktningen frĂ„n spannmĂ„ls- till ekologisk grĂ€sodling. ICECREAM-modellens databas omfattar alla finska avrinningsomrĂ„den, och jĂ€mförelse av modellresultat med mĂ€tresultat gav information om modellens förmĂ„ga att uppskatta effekter av produktionsriktning och klimat pĂ„ hydrologiska processer och nĂ€ringsĂ€mneskretslopp i marken. ICECREAM-modellen Ă„terskapade den observerade relativa förĂ€ndringen i fosforfraktioner: förĂ€ndringen frĂ„n odling av spannmĂ„l till grĂ€s ledde till att andelen rörlig fosfor av total fosfor ökade, och andelen partikelbunden fosfor minskade. Modellen överskattade den absoluta fosforbelastningen och avrinningen frĂ„n Ă„kern, vilket orsakade problem i den simulerade vattenbalansen.Description
Supervisor
Koivusalo, HarriThesis advisor
Huttunen, InesePaasonen-KivekÀs, Maija
Keywords
agricultural management system model, field hydrology, runoff, erosion, phosphorus
