Optimization of Field Topography in Surface Irrigation

Abstract

This work presents and applies a new methodology to find the optimal topography of a surface irrigation field, achieving a theoretically uniform surface irrigation. For any variant on surface irrigation (basin, border or furrow, with open or blocked end), the method's result is a particular curved topographical shape of a field. This shape distributes water evenly over the field, so that distribution uniformity is theoretically 100% and deep percolation disappears. The methodology is applied to two theoretical cases: a 1-D blocked-end field and a 2-D square field with corner inflow. For each case, the methodology reaches a particular topography where distribution uniformity is near 100%. To put into practice this methodology, the optimized topography (which has a curved shape) must be approached to a set of slopes. A real example is shown where a real field was laser-levelled with two consecutive slopes to fit the optimized topography, previously calculated with the methodology here presented. The irrigation was evaluated before and after the optimization. The results indicate an increase of distribution uniformity from 82% to 96%.

Strategies to Cope with Risks of Uncertain Water Supply in Spate Irrigation Systems

“…This is attributed to the upper-lower irrigation approach used to distribute irrigation water by gravity which exposes the top head parts of the fields to over-irrigation, sediment accumulation and large DP losses. Nevertheless, González-Cebollada et al (2011) attributed this phenomenon to the impact of surface topography. Therefore, increasing the application time to relatively improve performance will not be practical under existing water scarcity and demand pressure.…”

Statistical analysis of bedslope, shape and fertigation timing to reduce nitrate loss in furrow fertigation.

“…This requires proper fertigation techniques to avoid polluting surface and groundwater resources. To achieve a higher uniformity, it might be necessary to use more than one slope, which for each case is dependent on infiltration parameters, Manning roughness coefficient, amount and rate of irrigation flow, and field geometry (González-Cebollada et al 2016). Four different slopes were practiced on the furrow for this research.…”