Water 2015, 7, 898-917; doi:10.3390/w7030898 OPEN ACCESS
water ISSN 2073-4441 www.mdpi.com/journal/water Article
Exploring the Modifiable Areal Unit Problem in Spatial Water Assessments: A Case of Water Shortage in Monsoon Asia Aura Salmivaara *, Miina Porkka, Matti Kummu, Marko Keskinen, Joseph H. A. Guillaume, and Olli Varis Water & Development Research Group, Aalto University, Tietotie 1E, Espoo 02150, Finland; E-Mails:
[email protected] (M.P.);
[email protected] (M.Ku.);
[email protected] (M.Ke.);
[email protected] (J.H.A.G.);
[email protected] (O.V.) * Author to whom correspondence should be addressed; E-Mail:
[email protected]; Tel.: +358-50-4075171. Academic Editor: Athanasios Loukas Received: 4 November 2014 / Accepted: 27 February 2015 / Published: 3 March 2015
Abstract: Water shortage (availability per capita) is a key indicator of vulnerability to water scarcity. Spatial datasets enable the assessment of water shortage on multiple scales. The use of river basins and subbasins as analysis and management units is currently commonplace. An important but less acknowledged fact is that spatial assessments are strongly influenced by the choice of the unit of analysis due to the Modifiable Areal Unit Problem (MAUP). Climate conditions, agricultural activities, and access to groundwater also influence water availability and demand. In this study, a total of 21 different criteria were used to define areal units of analysis, i.e., zonings, for which water shortage was calculated. Focusing on Monsoon Asia, where water scarcity is a pressing problem, we found that zoning had a considerable impact, resulting in up to three-fold differences in the population under high water shortage (
