Water Use Bangkok October 2013

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

National Water Use Country % Agriculture% Industrial% Residential Bangladesh Cambodia Indonesia Lao PDR Maldives Mongolia Nepal Philippines Sri Lanka Thailand Viet Nam

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