Climate Change Adaptation - Climate Resilient Agriculture for Ensuring Food Security - page 239

Fig. 12.9 Farmland sprinkler system in Cajamarca, Peru (Source: Courtesy of David Dennis Rabines Alarcon)

agronomic management, can more than double
water productivity and yields in small-scale rain-
fed agriculture (UNEP and SEI 2009 ).

in dry periods or in time of prolonged drought.
Low storage capacity will limit rainwater harvest-
ing potential, whereas increasing storage capacity
will add to construction and operating costs, mak-
ing the technology less economically viable. The
effectiveness of storage can be limited by the
evaporation that occurs between rains. In water
basins with limited surplus supplies, rainwater
harvesting in the upstream areas may have a dam-
aging impact downstream and can cause serious
community confl ict. Also, when runoff is gener-
ated from a large area and concentrated in small
storage structures, there is a potential danger of
water quality degradation, through introduction of
agrochemicals and other impurities (UNEP and
SEI 2009 ).

12.3.2.3 Advantages
Rainwater harvesting technologies are simple to
install and operate. Local people can be easily
trained to implement such technologies, and con-
struction materials are usually readily available.
Rainwater harvesting is convenient because it
provides water at the point of use and farmers
have full control of their own systems. Use of
rainwater harvesting technology promotes self-
suffi ciency and has minimal environmental
impact. Running costs are reasonably low.
Construction, operation, and maintenance are not
labor intensive. Water collected is of acceptable
quality for agricultural purposes. Other benefi ts
include increasing soil moisture levels and
increasing the groundwater table via artifi cial
recharge. Rainwater harvesting and its applica-
tion to achieving higher crop yields can encour-
age farmers to diversify their enterprises, such as
increasing production, upgrading their choice of
crop, purchasing larger livestock animals, or
investing in crop improvement inputs such as irri-
gation infrastructure, fertilizers, and pest man-
agement (UNEP and SEI 2009 ).

12.3.3 Sprinkler Irrigation

Systems of pressurized irrigation, sprinkler or
drip, can improve water effi ciency and contribute
substantially to improved food production.
Sprinkler irrigation is a type of pressurized irriga-
tion that consists of applying water to the soil sur-
face using mechanical and hydraulic devices that
simulate natural rainfall (Fig. 12.9 ). These devices
replenish the water consumed by crops or provide
water required for softening the soil to make it
workable for agricultural activities. The goal of
irrigation is to supply each plant with just the right
amount of water it needs. Sprinkler irrigation is a
method by which water is distributed from

12.3.2.4 Disadvantages
The main disadvantage of rainwater harvesting
technology is the limited supply and uncertainty
of rainfall. Rainwater is not a reliable water source