Crop yield effect on water/electricity demand

The empirical relationship showing crop yield response to water deficit is available here (page 6) with original source available here. In brief, estimating how yield is affected under water stress, is rather complicated and affected by crop type and timing of water deficit, among others; the effect is different in vegetation phase rather than in ripening phase for example.

In the current modelling exercise we assume that the maximum evapotranspiration (ETx) is equal to the actual evapotranspiration (Eta) assuming disease-free, well-fertilized crops, grown in large fields under optimum soil water conditions. Based on that and the relationship described above, we also assume that the crops, if irrigated, can achieve maximum yields under the given climatic conditions (ya=yx).

Most relevant studies look on the effect that water deficit can have on yield and try to validate such relationships (back casting). Estimating/quantifying crop yield increase under irrigation is rather challenging. This study (page 75-76) shown the potential (%) increase in yield of a) water harvesting and b) different irrigation techniques for different regions and 3 crop types. It is though far from robust to provide empirical relationship we can use.

Based on the current review, a suggested approach for estimating impact on yield (thus productivity) would be to find country specific crop yields for irrigated and rainfed areas (available by Harvest choice) and assume that under irrigation the yield in rainfed areas will increase to reach yield in irrigated areas.

Useful sources to look:

akorkovelos / agrodem

Crop yield effect on water/electricity demand #13