Visualization of Water Services in Africa: Data Applications for Nexus Governance - Governing the Nexus: Water, Soil and Waste Resources Considering Global Change - page 193

Visualized in a meaningful manner, monitoring data enable the posing of rele-
vant questions and initiate relevant management strategies, channelling resources
and setting incentives. Such questions and the respective measures relate to spatial
comparisons (e.g. bad water quality in one region compared to others) and/or
temporal developments (e.g. water quality is deteriorating/improving/constant) and
the underlying data have to enable such analysis and visualization.
Monitoring of water services can be used to de ne proxies (e.g. drought index,

vegetation index) to establish models and empirical relationships (transfer functions)
that are applicable for monitoring. For example an empirical relationship model was
established that relates

field measured water body volume to remotely sensed water
body extensions (Liebe et al. 2005 ). This mathematical model can then be applied to
water volume monitoring of water bodies solely based on mapping of water body
extensions in future remote sensing images. The monitoring data could feed con-
nected models that in real-time update the connected maps (e.g. of water usage).
Continuous data input on water usage can be provided by mobile phone applications
by (and for) different users such as the public, experts or government members. In
Africa, the number of mobile phone subscriptions has increased over the last few
years. Previous data measurements and maps can be used as basis for additional
research surveys, as for example the choice of locations for interviews or supple-
mentary data sampling. Therefore, the application of spatial sampling methods is
crucial for monitoring, since they build the basis for designing monitoring networks
(e.g. de

nition of additional sampling locations) (Wang et al. 2013 ).

2.5 Circumventing the Science Policy Divide
in Data-Poor Conditions

For decision-makers it is important to communicate explicitly their concerns and
needs about environmental and socio-economic issues to scientists or other experts. It
is of importance to identify which scales and processes need to be considered. The
identi cation and communication of the needs is a type of feedback loop where the

needs have to be adjusted to state-of-the-art knowledge. For example research results
become available revealing that small-scale land-use changes can have an impact on
large-scale water quality, which might not have been assumed in the past. Therefore,
the choice of considered processes (biophysical and socio-economic) and scale
depends on the stated research question. For instance, river water usage has impli-
cations on regional scale (e.g. irrigation, soil salinization) as well as on a larger scale
(reducing downstream water supply for population and agriculture). Processes and
their feedback are therefore scale dependent. Thus, the question arises as to how we
can overcome the scale issue

particularly in data-poor environments.
First, each environmental and socio-economic analysis (e.g. risk analysis) as well
as predictions needs to be based on data. Since different kinds of processes have to be
considered, it is advantageous or even mandatory to work with a transdisciplinary or
nexus approach that integrates area/sector speci

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c knowledge and methods. Second,