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 was applied to two theoretical cases: (1) a one-dimensional blocked-end field, and (2) a two-dimensional square field with corner inflow. For each case, the methodology reached a particular topography in which distribution uniformity was near 100%. To put this methodology into practice, the optimized topography (which has a curved shape) can be fitted with two or more different slopes. An example is shown in which a real field was laser-levelled with two consecutive slopes to fit the optimized topography; it previously was calculated with the methodology presented in this paper. The irrigation was evaluated before and after the optimization. The results indicated an increase of distribution uniformity from 82 to 96%. The topographic optimization methodology offers new information about topography influence on irrigation performance indicators. The main practical conclusion is that this method can be useful to determine the best slope, set of slopes or curved shape when levelling any field for surface irrigation.

This work was supported by the Government of Arag ´on (Spain) and the European Social Fund (European Union).

20 Pags.- 2 Tabls.- 8 Figs. The definitive version is available at: http://ascelibrary.org/journal/jidedh

Peer reviewed