Integrative Economic Evaluation of an Infrastructure Project as a
Measure for Climate Change Adaptation: A Case Study of Irrigation
Development in Kenya
Abstract
As climate change adaptation is becoming a recognized policy issue, the
needs are growing about quantitative economic evaluation of
adaptation-related public investments, particularly in the context of
climate finance. Irrigation, which enhances and stabilizes water supply
for farming, is a potential means of climate change adaptation, but
attempts of economic evaluation of its effectiveness as an adaptation
measure are few in part because such assessment requires an integration
of various types of simulation analyses. Against this background, we
conduct a case study of a Kenyan irrigation development project (Mwea
Irrigation Development Project), which is undertaken by the Kenyan
government with a loan from the Japan International Cooperation Agency
(JICA), to evaluate the effectiveness of the project for climate change
adaptation by using a combination of simulation models. Specifically, we
conduct a simple downscaling of CMIP5 climate simulation data, whose
outputs are fed into a hydrological model (SHER model) and a yield
forecasting model (DSSAT model). With these simulation data, together
with data of socioeconomic parameters drawn from existing and original
surveys, we compute economic variables such as farmers’ average income.
Climate and other uncertainties are incorporated into analysis without
probabilistic weights (conforming to the Robust Decision Making
approach, e.g., Lempert et al., 2013) to highlight vulnerabilities for
local farming. The results show that despite uncertainties of
precipitation trends, increased temperatures due to climate change have
a general tendency to reduce rice yields, and that irrigation
development will mitigate that income impacts from the yield loss, i.e.,
it will likely be effective as a means for climate change adaptation.