A combined statistical approach for evaluation of the effects of land use, agricultural and urban activities on stream water chemistry in small tile-drained catchments of south Bohemia, Czech Republic

摘要: This work evaluates the changes of nitrate-nitrogen (NO3-N), ammonium-nitrogen (NH4-N), total phosphorus (P) and chemical oxygen demand (COD) concentrations in stream waters as related to land use/land cover (LULC) alterations within eight small (5–39 km2) tile-drained catchments southern part The Czech Republic period 1993–2010, when massive grassing arable took place. robust tools seasonal Mann–Kendall trend test LOcally WEighted Scatterplot Smoothing methods were employed reveal trends monitored parameters with adjustment hydrology. Using principal component analysis multiple regressions, statistically significant factors highest impacts on assessed water quality identified. Besides indicators LULC their various zones, information built tile drainage systems used along reflecting point pollution sources such population number, sewerage type proximity a watercourse, effectiveness wastewater treatment, number livestock units. change was essential only for NO3-N concentrations, land, presence ponds, areas permanent cultures also drained explained up 90.6 % variability showed significantly decreasing all during evaluated period. infiltration vulnerable zones discovered less important compared whole catchment area. However, NH4-N, P COD, results did not enable definite quantification effects changes. influence non-point these revealed uncertain heavily overshadowed by sources, particular management, numbers, although proportion subcatchments fundamental case COD. increasing numbers livestock, population, sewage treatment led some worsening quality. Achieved findings may be critical supporting policy management decisions.