Water scarcity and abundance, water productivity and their relation to poverty - Water Scarcity, Livelihoods and Food Security - page 26

catchments to manage their land and water better. They identified hotspots of
erosion, measured their impacts on water quality and identified land manage-
ment that reduces erosion and so improves downstream water quality (Estrada
et al., 2009; Quintero et al., 2009; Quintero, 2012).
Throughout the Andes, mining is notorious for contaminating water. It is a
growing cause of scarcity of clean water and was researched in the Andes BFP
project (Mulligan et al., 2009; Mulligan et al, 2012b). In the Conversatorio de
Acción Ciudadana process in Colombia, communities and institutions negotiated
legal agreements related to water in catchments (Candelo et al., 2008), which
inter alia find ways for benefits from mining to be used to address its negative
externalities. For example, benefit-sharing mechanisms have been negotiated
and implemented in ways that recognize the negative impacts of mining on
water and provide the resources to manage water quality directly at the mine
to reduce these impacts or by supporting improved management of other land
uses. Because mining is an important source of income, both locally and
nationally, it requires institutional tradeoffs when the national priority is to
reduce poverty ( Johnson et al., 2009).
In the Volta Basin, muddy water in the wet season causes scarcity. Rainfall
is not scarce in the basin as a whole but it is seasonal and varies from 1200
mm/yr in the south to less than 500 mm/yr in the north. Wet-season runoff
is difficult to store because much of the basin is too flat to build large dams
(PN55) (Lemoalle and de Condappa, 2012), but several thousand small dams
built over the last 20 years supply water in the dry season for domestic use,
livestock and small-scale irrigation. The small dams are in streams that are
hydrologically linked (PN46) (Andreini et al., 2010).
Most small dams in the White Volta Basin have problems with water quality
caused by cyanobacteria (potentially harmful microalgae) of unknown origin.
Pesticides and other pollution from agriculture also reduce water quality
(PN46) (Andreini et al., 2010). Cyanobacteria constrain the use of water from
small dams for households, fishing or irrigation (V3). Small dams also increase
the incidence of schistosomiasis and malaria (Boelee et al., 2009). Nevertheless,
water quality is better when communities improve their soil management and
use of pesticides (V3) (Cecchi and Sanogo, 2012).
In the Nile, water quality differs between upstream and downstream.
Siltation and livestock-related water pollution affects water quality in upstream
countries, leading to sedimentation of reservoirs and low quality for domestic
water. In downstream countries, ET is high, increasing salinity of the river
water, which in the delta reduces yields and limits the range of crops that
farmers can grow.
Another example of scarcity of water of suitable quality for particular
purposes comes from Ghana, where urban and peri-urban vegetable farmers
use urban wastewater for irrigation, posing a public-health risk. A CPWF
project developed strategies to safeguard public health without compromising
farmers' livelihoods. It assessed land and WP in farms irrigating with waste-
water and quantified levels of contamination on vegetables at points down the