The theory of river flow transport is the major cause in the development of the irrigation sector and largely determines the stability of the irrigation scheme. Crop water requirements vary due to climate and crop growth stages. For this reason, the flow of sediments changes during the irrigation season. In this article, in order to evaluate the carrying capacity of the canals, researches in natural field conditions were carried out in the Amu-zang canal belonging to the “Amu-Surkhan Irrigation Systems” basin administration. Flow transportability in natural channels was calculated for particles with d=0.05 mm by S.Kh.Abalyans, A.Zamarin, A.M.Arifzhanov and Engelund and Hansen methods. A histogram of the dependence of flow capacity, channel depth and average speed on the Amuzang channel was obtained, according to which it was determined that the flow capacity is 1.5-1.8 kg/m3 in the range of 0.6-0.8 m/s.