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A modelling approach to assess the impact of land mining on marine biodiversity: assessment in coastal catchments experiencing catastrophic events (SW Brazil).

Abstract:Here, we compared grid precipitation data -Climate Forecast System Reanalysis (CFSR) and WATCH Forcing Data methodology applied to ERA-Interim (WFDEI) data -with Brazilian Weather Bureau (INMET) and Brazilian Water Agency (ANA) rain gauge data (n = 2027) for the period 1980-2010 in order to evaluate which grid data set better represents precipitation, and is thus more suitable for hydrological modelling of Brazilian water resources. We found that WFDEI outperformed CFSR according to three statistical indicators. We then applied and interpolated a simple bias correction to further improve WFDEI data before we used these data to model river discharge of the Tocantins catchment with the Soil and Water Assessment Tool (SWAT). Calibration (validation in parentheses; weighted averages of all gauges) had satisfactory statistical metrics: p-factor = 0.52 (0.47); r-factor = 0.84 (0.99); R 2 = 0.78 (0.71); bR 2 = 0.68 (0.47); NS = 0.70 (0.66); Pbias = À4.5 (4.0). Finally, the calibrated SWAT model was used to assess the spatial distribution of the catchment's water resources. Annual green water flow (evapotranspiration) increased from the south-east (640-840 mm yr À1 ) to north-west (1140-1440 mm) of the Tocantins catchment, while green water storage (soil water content) increased from south (330-1070 mm) to north (2180-3290 mm). Blue water (water yield) had a less clear pattern, with lower values in the south and the central borders of the catchment (20-560 mm) and higher values along the central axis and the north (920-1460 mm). Our analysis suggested that WFDEI was an accurate representation of Brazilian precipitation. For large catchments, we therefore recommend the use of WFDEI instead of sparse and often missing rain gauge data in modelling Brazilian water resources.

Aim Neotropical biomes are highly threatened by land‐use changes, but the catchment‐wide biogeochemical effects are poorly understood. Here, we aim to compare exports of dissolved nitrogen (N) and phosphorus (P) from natural and human‐impacted catchments in the Neotropics. Location Neotropics. Methods We measured streamwater nutrient concentrations and exports in 20 south‐eastern Brazilian catchments with different land uses (natural Cerrado/semi‐deciduous forest, pasture, intensive agriculture and urban areas) and conducted a meta‐analysis on nutrient exports from Neotropical catchments, both natural and human‐impacted. Results Organic forms dominated dissolved nutrient exports in central/south‐east Brazil in both natural and human‐dominated catchments. Our meta‐analysis suggests that there is wide geographic variability in the natural dominance of organic versus inorganic nutrient exports across the Neotropics, and for N a tendency for inorganic and organic forms to vary inversely across sites. We found strong land‐use effects, especially in urban areas. In areas naturally dominated by organic N exports, land use did not overturn that dominance, but rather increased the concentration of both inorganic and organic N. In catchments dominated by inorganic N exports or showing equivalent organic and inorganic exports, land use also caused organic exports to be dominant. Land‐use effects on P were unclear, probably owing to a paucity of available data, but our results from south‐east Brazil suggested that land use also increases dissolved P exports. Main conclusions We show that dominance of inorganic versus organic nutrient exports is highly variable across natural Neotropical catchments, a pattern contrasting with the general tendency for dominance of organic N in natural temperate catchments. Further, we found a general dominance of organic N in most human‐impacted catchments, which is in contrast to strong dominance of inorganic N in most human‐impacted temperate catchments. Finally, we find that urbanization exerts the strongest impacts on nutrient exports, thus underscoring wastewater treatment as a critical management priority under future land‐use change.