تغييرات زماني و مكاني مقطع جريان در آبياري جويچه اي

Seasonal and spatial variation of furrow cross section

For evaluating the variation of geometry and hydraulic cross section coefficient and its simulation both in irrigation events (seasonal), and in furrow length (spatial), some experiments were developed on 24 furrows with a 60m length and 0.75m width in a sandy-loam soil in Isfahan, in summer 2001. Furrow cross sections were measured before and after of every irrigation event using profilemeter at 5, 30 and 55 m from upstream of the furrow. Geometry and hydraulic cross section coefficient were calculated were by using of CSCM, a computer based model. Based on the results, it was seen variation both seasonal and spatial, in the furrow cross section area (A) and its dependent coefficient. Evaluation of the geometric and hydraulic coefficient variation showed no systematic trend. In addition the effect of the a, a2 coefficients were evaluated on the y-An equation. Similarly the effect of the pi 4)2 evaluated on the y-Z2 equation. There was significant seasonal variation of furrow cross section area. But there wasnʹt any significant variation on squared shape factor (Z2) as a hydrawlically index. A linear equation was developed for the seasonal variation of both A and Z2. Based on the results, no systematic trend was observed between spatial variations of the parameters in a furrow because of complexity.