Investigation of non-point source pollution potential in the watershed of Porsuk dam reservoir


Tezin Türü: Yüksek Lisans

Tezin Yürütüldüğü Kurum: Orta Doğu Teknik Üniversitesi, Fen Bilimleri Enstitüsü, Fen Bilimleri Enstitüsü, Türkiye

Tezin Onay Tarihi: 2013

Öğrenci: Elif Küçük

Asıl Danışman (Eş Danışmanlı Tezler İçin): AYŞEGÜL AKSOY

Özet:

The achievement of good water quality status depends not only on point source control, but also on minimizing the contribution of non-point sources on pollution. Although non-point source pollution includes numerous components, agriculture has been considered as the primary activity responsible from deterioration in the quality of water resources. In this thesis, a hypothetical assessment was conducted to assess the relative impacts of different agricultural practices on the Watershed of the Porsuk Dam Reservoir (PDR). For this purpose, geographic information system (GIS) integrated Soil Water Assessment Tool (ArcSWAT2009) was used. Model performance was evaluated via Nash-Sutcliffe (NSE) and absolute percent deviation between simulated and observed yearly average flow values. Following manual calibration process, vulnerable areas for phosphorus transport were determined for ten different agricultural practice scenarios. These scenarios were developed to understand the effects of varying fertilizer and irrigation rates, land use changes and point source phosphorus loads on “soluble mineral forms of phosphorus transported by surface runoff into reaches” (SOLP). The most effective management scenario in terms of reduction in SOLP loads was determined as the combination of 50% and 20% decrease in fertilizer and irrigation rates, respectively. The corresponding decrease in the overall SOLP load to the PDR was calculated as 40%. In this scenario, mostly fertilizer reduction was effective in SOLP reduction. The most critical sub-basin that is responsible for the considerable SOLP load was determined. Moreover, other sub-basins which can be considered as the high concern areas within the watershed to control SOLP loads were identified.