Improving Furrow Irrigation Performance with Spatially Variable Cross-Section

Surface irrigation is being the most known method of irrigation in the world and Iran.This is because the furrow irrigation produces tail runoff water in which, efficiency is not as much as the other surface methods. Improving the efficiency by block ending increases scalding probability and controlling discharge need modern facilities and specialist. One of the variable to be managed is furrow geometry. At a constant flow, a depth V-shape cross-section makes advance rate faster and amount of infiltration less than wide U-shape cross-section. In order to find this, a 120 meter furrow was mated in a salty loam soil with two different cross-sections in at Agricultural Station of Tehran University located in Karaj. Furrow cross-sections were made with one furrower mounted to a tractor without any change. Data were collected, using two irrigation processes. Results indicated that a narrow end furrow reduces by advance time 5%,constant of the Kostiakov equation coefficient (a) and infiltration by and increases flow depth, soil moisture content and k coefficient and distribution uniformity respective by 10,19 and 4 to 7 percents 36 % in efficiency but flow depth 10 %, water content in bottom 19%, coefficient (k) and distribution uniformity 7-4% are increased. On the contrary, results obtained for wide U-shape were opposite. Lowest volume of runoff (19.6% of inflow) was produce in completed wide and narrow furrows. However, these variables on the second irrigation were less.