Water Use Bangkok October 2013 Measuring Water Use

Water Use Bangkok October 2013

Measuring Water Use • Four primary users – Agriculture- largest user – Industry- second largest – Residential- highest valued

National Water Use Country Bangladesh Cambodia Indonesia Lao PDR Maldives Mongolia Nepal Philippines Sri Lanka Thailand Viet Nam % Agriculture % Industrial 87. 8 94 81. 9 91. 4 0 43. 9 98. 1 82. 2 87. 3 90. 4 94. 8 % Residential 2. 1 1. 5 6. 5 4. 9 5. 1 43. 2 0. 3 10 6. 4 4. 9 3. 7 10 4. 5 11. 6 3. 7 94. 9 12. 9 1. 5 7. 6 6. 2 3. 7 1. 5

Watershed Analysis • Because it is expensive to move water from one watershed to the next, use and supply must be evaluated in each watershed • Can use national estimates for rough guess – Multiply national average use by number of users in watershed – Works well if watershed is like national average

Measuring Watershed Use • Survey a random sample of users in the watershed – Sample of farmers – Sample of urban and rural households – Sample of industrial users • Determine aggregate number of users of each type in the watershed from Census • Extrapolate from sample to aggregate

Withdrawal Versus Consumption • Determine from literature what fraction of withdrawals by each user is consumed • Dams consume very little • Farmers tend to consumer more • Industries vary – Pass through cooling very little – Evaporation towers 100%

Water Pollution • Use can consume only a fraction of water but pollute water heavily • Without treatment, polluted water may have limited use-effectively consumed • Water treatment plants turn low valued polluted water into high valued clean water – Effectively increase supply