Evaluating the impacts of climate change and crop land use change on streamflow, nitrates and phosphorus: A modeling study in Bavaria

Abstract

a b s t r a c tStudy region: Bavaria, Germany. Study focus: The Altmühl River is prone to nutrient inputs from agricultural activities. Quantifying nitrate nitrogen (NO 3 − -N) and total phosphorus (TP) concentrations due to potential future changes in the watershed is necessary for managing water quality and adhering to water policy directives. The Soil and Water Assessment Tool (SWAT) was used to provide stakeholders with support in determining the impacts of climate change (CC) in combination with crop land use change (LUC) scenarios on streamflow, NO 3 − -N and TP to the 2050 time horizon. The CC simulations stemmed from RCMs and the LUC scenarios were developed with stakeholders. New hydrological insights for the region: When CC was combined with LUC, mean annual NO 3 − -N loads increased 3-fold, and TP loads 8-fold, compared to the CC simulations alone. Nutrient loads were higher in several months due to the future increased annual precipitation plus the additional fertilizer input in the land use scenarios. The maize areas above the Altmühl Lake contributed greatly to TP loads, while winter wheat areas mainly contributed to NO 3 − -N loads. When CC was combined with LUC, the in-stream nutrient concentrations exceeded ministerial guidelines of 11 mg TP/L and 0.05 mgNO 3 − -N/L every month at the outlet. CC simulations combined with LUC scenarios demonstrated non-linear dynamics whereby the direction and the magnitude of impacts were not predictable from the individual changes alone.

Evaluating the Importance of Non-Unique Behavioural Parameter Sets on Surface Water Quality Variables under Climate Change Conditions in a Mesoscale Agricultural Watershed

“…The uncertainty is quantified by the 95% confidence intervals, the interquantile ranges, the percentiles, and the total spread of the monthly variables. The evaluation of the future nutrient loads in the Altmühl per se has already been presented in Mehdi et al (2015Mehdi et al ( , 2016.…”

“…Observed daily flows at the Thann (1981Thann ( -2010, Aha (1975Aha ( -2010 and Treuchtlingen (1948Treuchtlingen ( -2006 More detailed information on the model set-up for the Altmühl watershed is described in Mehdi et al (2015).…”

Effect of Climate Change on Hydrology, Sediment and Nutrient Losses in Two Lowland Catchments in Poland

“…Nearly all studies have shown that climate change is likely to have a significant impact on contaminants' loads. Most indicate an overall increase in contaminants loads [8][9][10][11][12][13][14][15][16]. It is obvious that this increase corresponds to water flow augmentation driven by precipitation increase.…”

Assessment of impacts of agricultural and climate change scenarios on watershed water quantity and quality, and crop production

“…Liu et al, 2015) and scenarios that reflect hypothetical shifts between various percentages of urban, forest, agricultural and other land use (Zhang et al, 2015(Zhang et al, , 2016Wu et al, 2015). Similar types of combined SWAT climate change/land use change studies have been performed in other regions including Asia (Sayasane et al, 2015;Singkran et al, 2015;Tan et al, 2015), Europe (Serpa et al, 2015;Mehdi et al, 2015b;Guse et al, 2015) and North America (Mehdi et al, 2015a;Neupane and Kumar, 2015;Goldstein and Tarhule, 2015).…”