Models for Describing Landscape Hydrochemical Discharge in Mountain Countries

Abstract

Using 34 river basins of the Altai-Sayan mountain country as an example, the universal mathematical models for seasonal and long-term dynamics of landscape water and hydrochemical discharges were developed. For this purpose, the system-analytical modelling and the solution of mathematical inverse problem were applied. The input factors of the models include monthly precipitation and mean monthly air temperature, spatially generalized for the country, as well as the cartographic information on the area and average altitude of individual landscapes in river basins, the altitude of the outlets, the length of river channels, and the area of arable land. The water and seven hydrochemical discharges (three nitrogen mineral forms ${\text{NO}}_{2}^{ - } ,\,{\text{NO}}_{3}^{ - } ,\,{\text{NH}}_{4}^{ + }$, phosphates ${\text{PO}}_{4}^{3 - }$, ions, total dissolved iron, suspended matter) are calculated for each of 13 specified landscape types in each river basin. The sensitivity of discharges to variations of environmental factors is evaluated. The Nash-Sutcliffe efficiency estimated as more than 0.65 for the models represent their good and very good performance. The models also make it possible to forecast the seasonal dynamics of discharges for any river basin in the country under study.