Transcript IRRIGATION AND WATER SCARCITY IN THE

The delicate balance between irrigated landscape and climate changes in human history
Irrigation in the Indus area, Pakistan
Climate change as explaining factor?
Human construction of environments
Fig.1.
Fig.3.
The Indus Basin Irrigation System of Pakistan
(Fig.1.) serves an area of 16 million hectares.
Water used to come from the rivers, but
nowadays, up to 80% of irrigation water comes
from groundwater. Tubewells are everywhere,
and the density is growing (fig.2.). Effects on
the groundwater tables are noticeable: they
generally dropped significantly in the last years.
Fig.2.
The growth in tubewells after 1960 coincides
with the well-known sharp increase in global
temperature in the last years (Fig.3.). Is this a
coincidence or a collective response from
farmers to changing climate?
In the 1960s, tubewells were installed to lower
too high groundwater levels. Farmers started to
use wells to irrigate their crops, as it allowed
high flexibility and control. High groundwater
levels were caused by irrigation development
from the 1850s onwards (Fig.4.). The colonial
This question is interesting, as it may build our
powers used irrigation to increase tax revenue
understanding of impacts of climatic changes in
and deal with famines – which could occur
the past. How did society cope with those? Did
because of yearly variations in the monsoon.
societies collapse because of climate change?
Using climate change to
explain societal change is
tricky. Human agency –
individual and collective –
is typically related to
short-term considerations
of different natures.
Maurits Ertsen
Water Resources Management
Delft University of Technology
[email protected]
EGU2011-1735
Fig.4.
Sources:
Figure 1: Ullah etal 2001 (IWMI WP24)
Figure 2: Qureshi etal 2010 (I&D 59, 107-116)
Figure 3: IPCC 2007 (AR4 Climate Report)
Figure 4: FAO 2002 (I&D Paper 61)
Easter Island: rachelincolombia.wordpress.com