The effect of land use change on soil and water quality in northern Iran

Abstract

Rapid urbanization has led to extensive land-use changes, particularly in developing countries. This research is aimed to investigate the role of land use and its effect on soil and water quality in Ziarat watershed focusing on four land uses: forest, pasture, cultivated and urban development. Soil samples were taken from a depth of 0–30 cm on each land use and were analyzed by completely randomized split-plot design in two geographical directions. Results showed that bulk density (BD), electrical conductivity (EC), pH, calcium carbonate equivalent (CCE), and soil particle density (DS) of the soil samples in pastures, cultivated and urban areas increased and the mean weight diameter (MWD), soil porosity (F), organic carbons (OC), total nitrogen (TN), exchangeable cations (Ca2+, Mg2+, K+, Na+), cation exchange capacity (CEC) and soil microbial respirations (SMR) decreased, respectively in comparison with the forest soils. For water quality evaluations, sodium adsorption ratio (SAR), electrical conductivity (EC), pH, total dissolved solids (TDS), bicarbonate (HCO3 −), chloride (Cl−), total hardness (TH), calcium (Ca2+), potassium (K+), sodium (Na+) and magnesium (Mg2+) were investigated in two areas: Nahrkhoran and Abgir stations. Results showed that the concentration of TDS, EC and HCO3 − in Naharkhoran station is higher than that in Abgir station. On the other hand, the concentration of TDS, EC and HCO3 − in Abgir station are the relatively higher due to its location. Total hardness had the same trend during the study years except in the last three years; however, TH showed an increase of 25% TH in Naharkhoran for the last two years. Cl−, K+ and SAR in Naharkhoran station increased by 61%, 22%, 78% and 56% respectively, in comparison with Abgir station. This study demonstrated that the trend of soil degradation and mismanagement of land use may increase the frequency of urban floods and human health problems.