The impacts of a drought on water users will depend upon:
- The extent to which water uses can be maintained by drawing on stored water
- How the available water is allocated among potential users. In the western U.S., water banking has developed as a drought management tool to supplement traditional reliance on surface water reservoirs
Broadly speaking, the term "water bank" has been applied to two very different types of arrangements:
- Groundwater storage projects
- Arrangements to facilitate voluntary water transfers through water rental markets. Both types of water bank help to mitigate drought impacts by increasing water supplies for highly valued uses during water–short periods
Kathleen A. Miller, "Managing Supply Variability: The Use of Water Banks in the Western United States," in D. A. Wilhite (ed.), Drought: A Global Assessment, Volume II, pp.70–86. Routledge, London, 2000.
Water banks serve to mitigate the economic impacts of a drought either by increasing the reliability of water supply or by facilitating short–term reallocation of water among users. This chapter examines two types of arrangements to which the term "water bank" has been applied. These are:
- Groundwater storage banks, which include active conjunctive use programs whereby surface water is used to recharge an aquifer, which is then used as a source of water supply during periods when surface water is less abundant
- Water transfer banks, which provide an established process or procedure to facilitate short–term transfers of water from willing sellers to willing buyers. The chapter concludes that both types of water banks can provide drought protection for highly valued water uses while allowing the traditional agricultural uses to continue in times of adequate supplies
Photo: A Tanzanian teenager scoops up muddy water from a well. Many of the world's aquifers are being pumped out faster than they can replenish, a process that will increase sea level rise.
Photograph by Lynn Johnson, National Geographic