1 Introduction
2 Consensus process and member’s participation
3 Method development
3.1 Identifying the right question
3.2 From withdrawal-to-availability to demand-to-availability and beyond
3.3 WULCA’s process for scarcity method selection
Criteria | DTAA
| DTAx | 1/AMD |
---|---|---|---|
Description |
\( {\mathrm{DTA}}_A=\left(\frac{\mathrm{Demand}}{\mathrm{Availability}}\right) \)
|
\( {\mathrm{DTA}}_x=\left(\frac{\mathrm{Demand}}{\mathrm{Availability}}\right)\times {\left(\frac{\mathrm{Demand}}{\mathrm{Availability}}\right)}^{0.34} \)
|
\( 1/\mathrm{AMD}=\frac{\mathrm{Area}}{\mathrm{Availability}-\mathrm{Demand}} \)
for Demand < Availability 1/AMD = Max for Demand ≥ Availability |
Pre-selection criteria of relevance regarding the question to be answered | Poor | Good | Good |
Stakeholders acceptance | Option eliminated by the working group in the pre-selection process and not further investigated | Low (3/33) Only academics | Good (26/33) Academics, industry, consultants, and government |
Robustness with closed basins | Limpopo shows higher scarcity (ranking and absolute value percentile) | Ganges, Yellow river, Murray, Darling, Colorado, Nile, Jordan, Indus, Syr Darya and Amu Darya, and Cauvery show higher scarcity (ranking and absolute value percentile) | |
Main normative choice | Absolute and relative availability have equal contribution to impacts (x = 0.34) | Regions where demand ≥ availability are set as maximal (equation is discontinuous) | |
Physical meaning | Two physical quantities, empirically combined in an index with no physical units (physical meaning for 0% of world surface) | Express a physical meaning up to the point where demand ≥ availability (physical meaning for 88% of world surface, monthly) |