Specific Features of the Formation of Water Flow and Pollution Export from Agricultural, Forest, and Urbanized Landscapes

Resumo

The overland flow from different landscapes during flood season and its variations under the effect of agrotechnical activities and climate in the southern Russian Plain have been evaluated based on the analysis of data from water balance plots. The present-day overland flow in forest steppe and steppe regions has been shown to be several times less than that 50–70 years ago. At the same time, the infiltration runoff (perched-water and groundwater runoff) has increased. The structure of the present-day river runoff and the contribution of the overland flow, the runoff from a hydrographic network area, and the runoff of infiltration origin in individual natural zones to the formation of the river runoff have been determined. The export of biogens in the Volga and Don basins, including that in urbanized areas, has been calculated based on the analysis of water samples in different landscape zones. Such export from urbanized landscapes has been shown to contribute little to the total export of biogens in these basins. The volume of biogens of diffuse origin considerably exceeds that of biogens carried out by wastewater. However, this relationship may change for large rivers and reservoirs since river water carrying diffuse biogens mostly moves for a long time before it reaches the main river partially self-purified, whereas wastewater biogens mainly directly flow into large rivers.