50
population growth occurs in developing countries. A large proportion of these coun-
tries is hosted in tropical climates characterized by highly unreliable rainfall and
frequent meteorological droughts and dry spells. Most of the poorest people in the
world (65–70 %) are among the 1.1 billion farmers who make their living from agri-
culture (FAOSTAT 2012 ).
Rainfall is the most important natural resource in dry environments. In arid and
semiarid regions, precipitation is generally lower than potential evaporation and
non-uniform in distribution, resulting in frequent drought periods during the crop
growing season, and usually comes in intense showers, resulting in surface runoff
and uncontrolled rill and gully erosion (Oweis and Hachum 2009 ). Despite its scar-
city, rainfall is generally poorly managed with much of it lost through runoff and
evaporation. Capturing rainwater and making effective use of it is crucial for any
integrated research and development project. Water harvesting (WH) can play an
important role in fulfilling the objectives of such projects. As the water shortage in
dry areas is a recurring crisis, people need information on how to capture and use
every available drop of water efficiently. WH is an effective and economical means
of achieving this objective and information on its various systems and techniques is
in great demand (Oweis et al. 2012 ).
Water harvesting is a method of water collection that has historically been
applied in arid and semiarid regions where rainfall is either not sufficient to sustain
good crop growth or where, due to the erratic nature of precipitation, the risk of crop
failure is very high (Prinz 1996 ) is now being employed all over the world. As new
developments are made, more and more regions employ WH to help offset pressures
on existing water resources. This resurgence in popularity comes on the crest of a
new wave of environmentalism and drive toward sustainable development where the
focus is on renewable sources of water collection. WH is aimed at reducing the pres-
sure that development, and the consequences thereof, has placed on what is now
considered a limited resource, our water (Prinz 2002 ).
This chapter deals with the methods and techniques of water harvesting to make
more water available to humans, animals and for irrigation purposes, in places
where rainwater is the only source of water. Details are provided on the main factors
for selection of reliable water harvesting technique that is sustainable under local
circumstances, including physical (hydrologic, terrain, and technical), cultural
acceptability and socioeconomic (institutional and economic) factors. The aim is to
compile a synthesis of experiences that can provide insight into rainwater harvest-
ing opportunities which address human wellbeing while continuing to sustain a
range of ecosystem services.
2 History of Water Harvesting
The act of harvesting rainwater, floodwater and groundwater has been practiced for
thousands of years, from the most rudimentary techniques to large, complex meth-
ods such as the Roman aqueducts. For many cultures, water harvesting was an
A. Yazar and A. Ali