In order to increase water productivity at the Collective Irrigation System (CIS) level it is
crucial to adapt the existing irrigation infrastructure, enhancing water intake at the source, as well
as its transport and delivery efficiency. Rehabilitation may involve structural changes and thus, a
large capital investment. This investment should be proportionate to the increase in climate resilience
associated to different rehabilitation alternatives. A methodology framework was developed to
evaluate CIS resilience to climate change considering different rehabilitation alternatives. The assessed
components were: (i) crop production systems; (ii) on-farm irrigation systems; and (iii) project
rehabilitation alternatives for the conveyance and distribution of the irrigation water from the source
to the farmer fields. This framework was applied to the Maiorga CIS, in central Portugal, to test
the methodology performance in assessing the impacts of climate change on the supply-demand
balance of the proposed rehabilitation alternatives and to evaluate their climate resilience, for the
representative concentration pathways, RCP4.5 and RCP8.5, and two time periods, 2041–2070 and
2071–2100. For each scenario, period, and rehabilitation alternative, irrigation requirements at the
source (demand) and stream flows (supply) were computed and the supply-demand balance was performed.
Projected increases in irrigation water demand varied between 5.5% for RCP4.5/2071–2100
and 35.7% for RCP8.5/2071–2100. For RCP4.5, 11% (2050) and 9% (2080) reductions in irrigation
water supply were projected, while for RCP8.5 the reduction ranges between 13% (2050) and 30%
(2080). The proposed framework determined that the rehabilitation alternatives considering just one
type of water source, without flow regularization and with open channel distribution to the farmer’s
field, have proved to be unviable due to low resilience to climate change.info:eu-repo/semantics/publishedVersio
