title: Nutrient load concept-reservoir vs. bay impacts: a case study from a semi-arid watershed.
abstract: Large flow-through reservoirs and lakes possess environmental gradients and monitoring programs are mostly adapted for cost and time effectiveness. Bay areas are often more isolated from the main water body and are likely to have unobserved different environmental processes and impacts. This study was performed at the Itaparica Reservoir, São Francisco River, located in semi-arid Northeast Brazil, with dendritic form. Water residence time in the Icó-Mandantes Bay was estimated by hydrodynamic flow and transport simulations. The P-chlorophyll a relationship was used to develop the P use efficiency coefficient for critical P load estimation of 25 μg P L-1. Phosphorus sources and input rates into a bay and the respective reservoir were calculated and compared regarding their different origins for the period after flooding (1988) and for 2013. After impoundment, the P load highly exceeded the carrying capacity because of leaching and mineralization processes. In 2013, P inputs were still above this threshold, whereas inflow and sub-basin P export during the rainy season were crucial. But eutrophication processes have increased in the bay relative to the main water body. Hence, water in hydraulic isolated parts is prone to eutrophication processes, thus, bays have to be specially considered in water resource management.
authors.affiliation: Department of Water Quality Control, Technical University of Berlin, Straße des 17. Juni 135, Berlin 10623, Germany E-mail: florian.selge@tu-berlin.de.
authors.forename: F
authors.initials: F
authors.lastname: Selge
authors.affiliation: Chair of Water Resources Management and Modeling of Hydrosystems, Technical University of Berlin, Gustav-Meyer-Allee 25, Berlin 13355, Germany.
authors.forename: E
authors.initials: E
authors.lastname: Matta
authors.affiliation: Chair of Water Resources Management and Modeling of Hydrosystems, Technical University of Berlin, Gustav-Meyer-Allee 25, Berlin 13355, Germany.
authors.forename: R
authors.initials: R
authors.lastname: Hinkelmann
authors.affiliation: Department of Water Quality Control, Technical University of Berlin, Straße des 17. Juni 135, Berlin 10623, Germany E-mail: florian.selge@tu-berlin.de.
authors.forename: G
authors.initials: G
authors.lastname: Gunkel
mesh_terms: D061006:Bays; D001938:Brazil; D002734:Chlorophyll / Q000737:chemistry / Q000378:metabolism; D017753:Ecosystem; D004784:Environmental Monitoring; D005068:Eutrophication; D010758:Phosphorus / Q000032:analysis; D045483:Rivers / Q000737:chemistry*; D014874:Water Pollutants, Chemical / Q000737:chemistry* / Q000633:toxicity; D014881:Water Supply
chemical_list: D014874:Water Pollutants, Chemical; D002734:Chlorophyll; D010758:Phosphorus