838 Benefits of Water Harvesting
Rainwater harvesting (RWH) is as old as human settlements. It is practiced in many
different forms both in rural and urban landscapes, often in small-scale, decentral-
ized ways. A growing number of cases describing the multiple benefits of rainwater
harvesting have emerged. There is evidence of increased human wellbeing, and
sustained or enhanced ecosystem services by water harvesting intervention from
developing countries such as India, various sub-Sahara African, transition countries
such as Brazil and China through to developed countries such as USA, Australia
(UNEP-SEI 2009 ; Oweis et al. 2012 ).
There are numerous positive benefits for harvesting rainwater. The technology is
low cost and highly decentralized which empowers individuals and communities to
manage their water. It has been used to improve access to water and sanitation at the
local level. In agriculture, rainwater harvesting has demonstrated the potential to
double food production by 100 % compared to the 10 % increase from irrigation.
Rainfed agriculture is practiced on 80 % of the world’s agricultural land area and
generates 65–70 % of the world’s staple food. For instance, more than 95 % of the
farmland is rainfed in Africa and almost 90 % in Latin America (UNEP-SEI 2009 ;
Mekdaschi and Liniger 2013 ).
Macro- and micro-catchment rainwater harvesting systems have a variable but
positive impact on soil moisture regimes and crop yields (Walker et al. 2005 ; Wei
et al. 2005 ; Mupangwa et al. 2006 ). Li and Gong ( 2002 ) and Tian et al. ( 2003 ) found
that MCWH of ridges and furrows with plastic mulch increased tuber yields of
potatoes by 158–175 % for two years and corn yield by 1.9 times due to higher
water use efficiency (WUE). The plastic used to mulch the ridges poses environ-
mental problems so biodegradable plastic film should be used (Wang et al. 2008 ).
Aftab et al. ( 2012 ) concluded that WH systems were a relatively low-cost option for
temporary access to a water source. RWH minimizes some of the problems associ-
ated with irrigation, such as competition for water among various uses and users,
low water use efficiency, and environmental degradation. RWH is a simple, cheap
and environmentally-friendly technology that can easily be managed with limited
technical skills (Ngigi 2003 ).
Besides the increase in agricultural productivity, RWH technologies also enhance
household food security and rising incomes (Mutekwa and Kusangaya 2006 ).
Specifically, Vohland and Barry ( 2009 ) concluded that in situ RWH practices
improved hydrological indicators such as infiltration and groundwater recharge,
improved soil nutrients, increased biomass production and improved soil tempera-
tures (Li et al. 2000 ). RWH practices enhance floral diversity, modify the spatial
structure of the ecosystem and increase animal biodiversity as more biomass is
available for food and shelter (Rockström et al. 2004 ).
Experimental plots by Abu-Zreig and Tamimi ( 2011 ) of in situ WH with a sand
ditch significantly reduced runoff and sediment loss by 46 and 60 %, respectively,
Water Harvesting in Dry Environments