Innovations in Dryland Agriculture

70

future use. Not only does this recharge depleting groundwater sources, it raises the
declining water table and helps to augment the water supply (Prinz and Singh 2000 ).
Qanats are an example of how an aquifer can be accessed to provide fresh water.
Widely used in Iran, Pakistan, North Africa and Spain, the Qanat consists of a hori-
zontal tunnel that taps underground water in an alluvial fan, bringing it to the sur-
face due to gravitational effects (Fig. 15 ). Qanat tunnels are on a 1–2 % incline up
to 30 km long. Many are still maintained and steadily deliver water for agricultural
production and villages for drinking water supply (Prinz and Singh 2000 ).

5 Main Consideration for Selection of Water Harvesting

Techniques

To reliably select a water harvesting technique suitable for local circumstances, the
characteristics of the different techniques need to be reviewed and include those that
are physical (hydrologic, terrain and technical), culturally acceptable and socioeco-
nomic (institutional and economic) in nature (Critchley et al. 1991 ; Ngigi et al.
2005 ; Bewket 2007 ; Lasage et al. 2008 ; Tumbo et al. 2011 ).
Water harvesting measures should be technically applicable under the physical
circumstances in the field. However, it is important to account for cultural accep-
tance of the technique and the need for simple governance after implementation.
Governance is necessary if the available water needs to be shared among many
people in one village or between several villages. There are many examples of water
harvesting projects that have failed to meet targets due to the complexity of gover-
nance, or because they were not acceptable to the population for cultural, environ-
mental or economic reasons. The resources needed for construction (physical, labor,
knowledge, capital) and their effects on the surrounding environment and hydro-
logical conditions (quality and quantity) also need to be taken into account. Water

Rainfall in catchment &

groundwater recharge

Natural ground surface

Verticle shafts

Groundwater table

Horizontal water shaft

Fig. 15 Groundwater harvesting Qanat by sketch

A. Yazar and A. Ali