Estimating catchment nutrient flow with the HBV-NP model: sensitivity to input data

The dynamic catchment model HBV-N has been further developed by adding routines for phosphorus transport and is now called the HBV-NP model. The model was shown to satisfactorily simulate nutrient dynamics in the R?nne? catchment (1,900 km2). Its sensitivity to input data was tested, and results demonstrated the increased sensitivity to the selection of input data on a subcatchment scale when compared with the catchment scale. Selection of soil and land use databases was found to be critical in some subcatchments but did not have a significant impact on a catchment scale. Although acceptable on a catchment scale, using templates and generalization, with regards to emissions from point sources and rural households, significantly decreased model performance in certain subcatchments when compared with using more detailed local information. A division into 64 subcatchments resulted in similar model performance at the catchment outlet when compared with a lumped approach. Adjusting the imported matrixes of the regional leaching of nitrogen, from agricultural land, against mean subcatchment water percolation did not have a significant impact on the model performance.     

Consequences of changed wetness on riverine nitrogen – human impact on retention vs. natural climatic variability

The HBV-N model was used for a scenario analysis of changes in nitrogen retention and transport caused by alterations of wetness due to land drainage, lowering of lakes, building of dams and climatic variability in a river basin in south-central Sweden (1885–1994). In general, dams were situated in locations more favourable for retention, compared to the lowered lakes. Rather modest conversions of water bodies only changed nitrogen transport by about 3%. The 180-times-larger increase of (mainly) tile-drained agricultural land had, according to simulations, increased the nitrogen transport by 17%, due to reduced retention. However, compared to human-induced alteration of the landscape N retention, the choice of 10-year periods of climatological data had the overriding effect on the calculated nitrogen transport. Weather-induced variations resulted in a 13% difference in nitrogen retention between various 10-year periods. When the model was driven by climatological data from the driest 10-year period (1905–1914), the estimated average annual load was only half of that obtained with climatological data from the wettest 10-year period (1975–1984). Electronic Publication     

Ensemble Modeling of the Baltic Sea Ecosystem to Provide Scenarios for Management

We present a multi-model ensemble study for the Baltic Sea, and investigate the combined impact of changing climate, external nutrient supply, and fisheries on the marine ecosystem. The applied regional climate system model contains state-of-the-art component models for the atmosphere, sea ice, ocean, land surface, terrestrial and marine biogeochemistry, and marine food-web. Time-dependent scenario simulations for the period 1960–2100 are performed and uncertainties of future projections are estimated. In addition, reconstructions since 1850 are carried out to evaluate the models sensitivity to external stressors on long time scales. Information from scenario simulations are used to support decision-makers and stakeholders and to raise awareness of climate change, environmental problems, and possible abatement strategies among the general public using geovisualization. It is concluded that the study results are relevant for the Baltic Sea Action Plan of the Helsinki Commission.     

Integrated catchment modeling for nutrient reduction: scenarios showing impacts, potential, and cost of measures

A hydrological-based model (HBV-NP) was applied to a catchment (1900 km2) in the southern part of Sweden. Careful characterization of the present load situation and the potential for improved treatment or reduced soil leaching were analyzed. Several scenarios were modeled to find strategies to reach the Swedish environmental goals of reducing anthropogenic nitrogen load by 30% and phosphorus load by 20%. It was stated that the goals could be reached by different approaches that would affect different polluters and social sectors. However, no single measure was enough by itself. Instead, a combination of measures was necessary to achieve the goals. The nitrogen goal was the most difficult to attain. In order to be cost-effective, these measures should be applied to areas contributing the most to the net loading of the sea. This strategy could reduce the costs by 70%-80% when compared with implementing the measures in the entire catchment. Integrated catchment models may thus be helpful tools for reducing costs in environmental control programs.     

Parameter precision in the HBV-NP model and impacts on nitrogen scenario simulations in the Rönneå river, southern Sweden

The HBV-NP model is a newly developed water quality model that describes the turnover and fluxes of both nitrogen and phosphorous. It is based on the conceptual precipitation/runoff HBV model. The HBV-NP model was applied for simulation of nitrogen for the R?nne? catchment in southern Sweden. The catchment was divided into 64 subcatchments in the model. Discharge measurements from six stations and nitrogen measurements from 12 stations were used in the calibration of parameters in the model. Eight automatic calibrations were performed with different combinations of time periods, objective functions, and levels of the nitrogen load in the model. A regionally extended interpretation of the Nash-Sutcliffe R2 criterion was used in the calibration. In the evaluation of the criterion, the errors were summed over both time steps and sampling points. Scenario simulations of combined measures for reduction of nitrogen load into the sea by 30% were thereafter performed with the eight sets of parameters established by calibration. The model parameters were not uniquely defined by the calibration. However, the simulated relative reduction of nitrogen load into the sea was relatively insensitive to the choice of parameter set, given the available input sources, variables, and data.     

Modeling the impact of potential wetlands on phosphorus retention in a Swedish catchment

In southern Sweden, wetlands are constructed to remove nitrogen (N) in agricultural catchments. The possible effects of such wetlands on riverine phosphorus (P) were also estimated using input-output data from three well-monitored wetlands. This was done to formulate a simple model for removal of P that is dependent on inflow characteristics. Next, the N- and P-reducing effects of wetlands were modeled on a catchment scale (1900 km2) using the HBV-NP model and various assumptions about the wetland area and location. All three wetlands functioned as sinks for total P (tot-P) and for total suspended solids (TSS) with a removal of 10% to 31% and 28% to 50%, respectively. Mean P-removal rates of 17-49 kg ha(-1) yr(-1) were well simulated with the model. Catchment scale simulations indicated that wetlands were more efficient (in percentage of load) as traps for P than for N and that this may motivate the construction of wetlands for P removal far upstream from the catchment outlet.     

工业化加工和家庭烹饪:三种备餐方法的环境效应评估

在当今的瑞典,食品的工业化加工代替传统的家庭制作的趋势越来越明显,公众担心由此可能增加的来自食品的环境影响.本文采用生命周期评估的方法,对三类食品--家庭制作的食品、半成品和即食成品的环境效应进行了定量的分析.结果表明:这些食品对环境的影响基本一致,即食成品消耗了最多的能源,而家庭制作的食品具有较高的排放量,引起富营养化作用和全球变暖;对环境的影响最大因素是农业,因为其30%的影响关系到能源,95%的影响关系到富营养化作用,工业、包装业、消费者家庭运输和食品制备方式对环境也具有明显的影响;加工业、家庭制作、包装业、废物处理过程中的原材料的消耗和能源效率是重要的因素,所以降低食品消费带来的环境影响,农业方面的改进是非常重要的,同时工业和家庭制作食品过程中的原材料利用也是非常重要的环节.     

Climate Change Impact on Riverine Nutrient Load and Land-Based Remedial Measures of the Baltic Sea Action Plan

To reduce eutrophication of the Baltic Sea, all nine surrounding countries have agreed upon reduction targets in the HELCOM Baltic Sea Action Plan (BSAP). Yet, monitoring sites and model concepts for decision support are few. To provide one more tool for analysis of water and nutrient fluxes in the Baltic Sea basin, the HYPE model has been applied to the region (called Balt-HYPE). It was used here for experimenting with land-based remedial measures and future climate projections to quantify the impacts of these on water and nutrient loads to the sea. The results suggest that there is a possibility to reach the BSAP nutrient reduction targets by 2100, and that climate change may both aggravate and help in some aspects. Uncertainties in the model results are large, mainly due to the spread of the climate model projections, but also due to the hydrological model.     

Climate change impact on water quality: model results from southern Sweden

Starting from six regional climate change scenarios, nitrogen leaching from arable-soil, water discharge, and nitrogen retention was modeled in the R?nne? catchment. Additionally, biological response was modeled in the eutrophic Lake Ringsj?n. The results are compared with similar studies on other catchments. All scenarios gave similar impact on water quality but varied in quantities. However, one scenario resulted in a different transport pattern due to less-pronounced seasonal variations in the hydrology. On average, the study shows that, in a future climate, we might expect: i) increased concentrations of nitrogen in the arable root zone (+50%) and in the river (+13%); ii) increased annual load of nitrogen from land to sea (+22%) due to more pronounced winter high flow; moreover, remote areas in the catchment may start to contribute to the outlet load; iii) radical changes in lake biochemistry with increased concentrations of total phosphorus (+50%), total nitrogen (+20%), and planktonic algae such as cyanobacteria (+80%).