Sediment transport in furrow irrigation

Abstract

Irrigation-induced erosion in furrow irrigation causes loss of fertile soil and water quality degradation. Hence, quantification of irrigation-induced erosion is essential for efficient management of furrow irrigation. In this study, sediment transport was studied under bare and cropped field conditions for a furrow plot consisting of three parabolic shaped furrows of 40 m long and 0.5% slope. The inflow rates of 0.2, 0.3, 0.4 and 0.5 L s⁻¹; and 0.3, 0.4, 0.5, 0.6 and 0.7 L s⁻¹ were used for bare and cropped field conditions, respectively. The furrow cross section measured at every 5 m distance from the head end (before and after the irrigation event) was used to study the erosion pattern (erosion/deposition) along the furrow. The runoff collected at regular intervals of 10 min was used to study the sediment load. The total sediment export for an irrigation event was estimated using furrow cross-section data (FCD) and the sediment rate data (SRD), and compared with the total sediments collected at the tail end. For both bare and cropped conditions, soil erosion took place at the head and tail ends (free drain system), while the deposition occurred at the middle. The sediment transport increased initially and slightly decreased with time. A power relationship was obtained between the total sediment export and the inflow rate for bare furrow condition, whereas a linear relationship between these parameters was obtained for cropped field condition. The relative percentage errors suggested that both SRD and FCD methods can be used to estimate total sediment export from the field. The analysis (PSD) of the total sediments revealed that the geometric mean diameter of the sediment particle was 0.18 and 0.20 mm for bare and cropped field conditions, respectively.