Kandidátska dizertačná práca

Pavla Pekárová

PhD. thesis

In the thesis, three basic methods of estimation, modelling and simulation of agricultural non-point source pollutant loading were studied:

a)   estimation on the basis of unit-area loads (yield);

b)   development of experimental relationships;

c)   integrated non-point source watershed models.

In the first part of the thesis, the impact of forestry, agriculture and urban activities on the quality of surface water is being analysed. Daily data from fifteen forest and agricultural experimental catchments of IH SAS were used.

The main results of the study are as follows:

*       The nitrate concentrations in surface water have decreased in Slovakia after 1989 as a result of decreased consumption of inorganic nitrogen fertilisers (lower intensity of agricultural production in Slovakia due to economic changes).

*       The theoretical problem of lower zero boundary of pollutant concentration series was solved in case of mean monthly stream concentrations modelling using SARIMA model. Nitrate concentration series were transformed using log-normal function. Due to this the modelled concentration values were shifted to positive numbers. Similar approach can be used in case of any hydrological series (discharge, precipitation, etc.). This procedure was used when predicting the nitrate concentrations in Ondava stream by SARIMA model 36 months ahead (see fig. Obr. 1).

*       The empirical relationships for indirect determination of nitrate stream concentrations were determined for three sub-basins of Ondava river. They are based on mean monthly runoff, precipitation totals, temperatures and annual fertiliser doses. The empirical relationships could be generalised for any catchment including the parameter of agricultural land percentage Agr. The results might be further improved by distinguishing the winter-spring and summer-autumn seasons. Also the parameter F (fertiliser doses) should be monthly distributed.

 *       The subchapter IV.5 is the essential part of the thesis. In this part there are elaborated the main methods of agricultural non-point source pollutant loading estimation in the stream with four time steps: 1. annual; 2. monthly; 3. daily; 4. single rainfall-runoff event.