Chapter 3 Decision Support Model (IUWS-DSM) - Tubdok

Chapter 1 General Introduction
Chapter 1 · General Introduction 1
The water scarcity is becoming the global issue. Meantime, the situation is getting worse
caused by many reasons, especially by population explosion, industrialisation and
urbanisation, as well as the climate change. This chapter draws the general overview of
current urban water systems, shows the development trend of urban water systems, and
gives a short introduction to the decision support systems. Subsequently, the scope and
objectives of this research work are presented.
1.1 Urban water systems
Along the development of human beings’ society, more and more people are going to live
in cities. The world urban population had reached 3,15 billion as 48,7% of the global
population in 2005, and till 2030 this will increase to 4,91 billion as 59,9% of the total
population (UN 2006). As the highly condensed settlement areas, modern cities are the
complicated giant aggregate with miscellaneous functions.
The water, as the essentials of life, must be fully and safely supplied in modern cities. It
has been clearly realised that fresh water is the limited resource. It is even predicted by the
World Meteorological Organisation that our water resources will be rapidly depleted by the
explosive growth of cities (Obasi 1997). Figure 1 pictures an overview of worldwide water
use based on the sectors. Clearly, water use in all sectors is dramatically increasing till 2025.
The very low use efficiency in domestic and industrial sectors is constently kept that is the
serious problem.
Figure 1: Evaluation of global water use – withdrawal and consumption by sector (UNESCO 1999)