Analysis and simulation of nutrient retention and management for a lowland river-lake system

Abstract

Abstract. In the context of the European Water Framework Directive, we studied the possible impact of reduced emissions on phosphorus and nitrogen concentrations in a lowland river-lake system (Havel River, Germany). As a prerequisite, we quantified the retention of nutrients in the river from mass balances and deduced its seasonal variation. We detected that about 30% of the total nitrogen input is retained within the surveyed river section. In contrast, phosphorus release from sediments was shown to cause a considerable increase in present P concentrations. Average net phosphorus release rates of about 20 mg P m −2 d −1 in late summer were estimated for the Havel Lakes. Based on the observed patterns of N retention and P release we parametrized a newly developed water quality simulation program (TRAM), which allows alternative model approaches of different complexity to be implemented and tested. To account for the future trend of internal P loading, the phosphorus excess in lake sediments was estimated from core samples and included in the model as a state variable. For analyzing scenarios of reduced nutrient emissisions, the water quality simulation program was linked to mesoscale hydrological catchment models for the first time. From scenario simulations we conclude that internal P loading is likely to counteract efforts of emission control for decades. Even by significant reductions in external P loads, a persistent phosphorus limitation of primary production can hardly be established in the analyzed time frame of 13 years. Though in the short run a continued reduction in nitrogen loads appears to be the more promising approach of eutrophication management, we recommend enhanced efforts to diminish both N and P emissions.

Water Environment Characteristics at Taige Canal-Taihu Lake: a Comparative Study on Interaction between Chlorophyll α and Environmental Variables

“…Both TN and NH 3 -N reached their peaks in winter, valleys in summer. Similarity phenomenon was observed in other RLCSs [24] and lakes [14], which may be attributed to the high efficiency of denitrification in high-temp seasons. But TN always reached its peaks two months earlier than that of NH 3 -N. These results suggested that organic nitrogen transformed into NH 3 -N during this period.…”

Modelling the effects of nutrient loads reduction and testing the N and P control paradigm in a German shallow lake

“…A high P release potential was already found by Kneis et al (2006) for other downstream Havel River lakes. Fig.…”

“…The use of a hydrodynamic model able to simulate transport and mixing in waterbodies is here important because these processes can influence strongly the dynamics of eutrophication (Lindim et al, 2011). The inclusion of a benthic module to predict the contribution of diagenetical processes is of major importance to simulate water quality in the Lower Havel since phosphorus internal loads have been found to be a main contributor to water column nutrient levels (Kneis et al, 2006).…”

“…With six urban wastewater treatment plants discharging treated effluents in the waterways, eutrophication is a water quality problem in the Lower Havel (Kneis, 2007). Efforts to reduce nutrients input have been made since the 1990s but nutrient concentrations remain high (Kneis et al, 2006). Attempts to control eutrophication in the Lower Havel have been so far centred on phosphorus reduction only.…”

A lightweight framework for rapid development of object-based hydrological model engines

“…This includes water quality simulation (Kneis et al, 2006(Kneis et al, , 2009, flood retention modeling (F€ orster et al, 2005), and runoff forecasting (Kneis et al, 2012). At a certain level of abstraction, the specific model engines used in the cited studies were actually identical.…”