Understanding and mitigating drought

According to the B.C. River Forecast Centre, “this is not a simple question to answer as there is no easy, quantifiable definition of a drought.

“There are generally considered to be three types of drought that may occur separately or in combination. These are: meteorological droughts (measured by lack of precipitation); agricultural droughts (measured by lack of soil moisture to support crops; and hydrologic droughts (measured by low water levels in streams, lakes, and wells).”

While drought is a normal, recurrent feature of climate, many people erroneously consider it a rare and random event. As described by the National Drought Mitigation Center (NDMC) in the U.S., drought “occurs in virtually all climatic zones, but its characteristics vary significantly from one region to another…Drought is the most complex of all natural hazards, and affects more people than any other hazard. Analysis shows that it can be as expensive as floods and hurricanes.”

What are the effects of drought?

The NDMC notes that, “The impacts of drought are greater than the impacts of any other natural hazard. They are estimated to be between $6 billion and $8 billion annually in the United States and occur primarily in the agriculture, transportation, recreation and tourism, forestry, and energy sectors.”

The NDMC also states that, “Society’s vulnerability to drought is affected by (among other things) population growth and shifts, urbanization, demographic characteristics, technology, water use trends, government policy, social behavior, and environmental awareness. These factors are continually changing, and society’s vulnerability to drought may rise or fall in response to these changes. For example, increasing and shifting populations put increasing pressure on water and other natural resources—more people need more water.”

As described by the B.C. River Forecast Centre, drought can have far-reaching impacts on our province.

Water Supply: “Most reservoirs and storage dams in B.C. rely on filling from runoff from winter rains (on the coast) and from snowmelt (in the interior). Reservoirs that do not fill from these sources generally will be unlikely to make up the deficiency later in the year unless the spring and summer are much wetter than usual. This can obviously impact water supply for domestic use, irrigation, and hydroelectric power—particularly later in the year if dry conditions persist.”

Agriculture: “Non-irrigated agriculture depends on soil moisture levels, and the lack of precipitation over the winter will normally result in lower soil moisture levels in many areas. The recovery from dry conditions can, however, be quite quickly achieved if there is close to normal rainfall later in the spring and summer. Agriculture relying on irrigation normally depends on a surface water source (river or stream) and these are unlikely to recover from a winter/spring drought unless subsequent precipitation is substantially greater than normal.”

Forestry: “The most apparent effect of dry conditions on forestry is the increased risk of forest fires. A dry winter/spring can have the result of an early start to the forest fire season than normal and the likelihood that the fires will be more intense than under wetter conditions. Again, subsequent wet conditions can quite rapidly reduce the hazard levels.”

Fish: “Lower than normal snowpacks will probably mean that affected rivers will peak at lower than normal levels during freshet—and quite possibly that the peaks will occur earlier than normal. In the major rivers this usually has the effect of lower flows for the rest of the summer, very often resulting in warmer water temperatures. Both low flows and warm temperatures increase stress and hence mortality levels in fish.”

How is drought monitored and measured?

In B.C., water levels are monitored and measured by the B.C. River Forecast Centre. Under the auspices of the Ministry of Water, Land and Air Protection, the centre posts up-to-date information on its website at wlapwww.gov.bc.ca/rfc/river_forecast/drought_monitor.htm

During winter and early spring, the centre utilizes Snow Water Equivalent Indexes and a Standard Precipitation Index (SPI) as indicators of future drought conditions. Snow Water Equivalent Indexes for snowpacks in B.C. can be found in the website’s Snow Bulletin from January 1st to June 15th. Precipitation for the last 12 months is mapped at the centre’s new B.C. Standardized Precipitation Indexes page. To better track present conditions, improved groundwater coverage and graphing, with mapping of percentages above or below normal groundwater for a given date, has been added to the website. It also shows comparative flow graphs, comparing the current weekly average flow with median flows, and five- and 20-year return period low flows, over the historic record of the flow station.

What are the stages of drought?

As defined by the American Water Works Association in a Drought Fact Sheet, there are four stages of drought, each of which requires different responses.

Stage 1: Watch

There is a five to ten percent water shortage. Utilities should initiate education campaigns for the public and government bodies. Voluntary reductions should be promoted through media campaigns, brochures, bill stuffers, etc.

Stage 2: Warning

There is a ten to 20 percent shortage. Utilities should continue with rigorous public information campaigns. They should explain drought conditions, disseminate technical information, and encourage ten-to-20 percent mandatory or voluntary water-use reductions.

Stage 3: Emergency

There is a 20 to 35 percent shortage. Utilities should introduce mandatory reductions and institute rationing programs through fixed allotments based on per capita or per household data. Outside allotment can be based on lot size, past usage, or other data. Require all homes to have low-flow showerheads and toilet displacement devices or ultra-low flow toilets before granting increased allotment.

Stage 4: Critical

There is a 35 to 50 percent shortage. Utilities should continue with mandatory reductions and intensify emergency strategies from Stage 3. Utilities should monitor production for compliance with necessary reductions weekly. They should allocate water on a per-capita or per-household basis for residential customers and apartments. No additional water should be used for outdoor or summer use.

How can we plan for drought?

There are many drought contingency plans in place across North America. According to the AWWA, “Some use a staged approach as described above, others, however, are embracing the modern approach of drought preparedness to put into place programs and projects to minimize and/or avoid drought impacts.”

As noted in the NDMC handout The Basics of Drought Planning: A 10-Step Process, “droughts are a normal part of virtually any climate, so it’s important to develop plans to reduce their impacts.” The plans, which involve a wide range of tools including policies, activities and programs, “give decision makers the chance to relieve the most suffering at the least expense.”

The 10 steps are as follows:

  1. Appoint a Drought Task Force
  2. State the purpose and objectives of the Drought Plan
  3. Seek stakeholder participation and resolve conflict
  4. Inventory resources and identify groups at risk
  5. Develop organizational structure and prepare Drought Plan
  6. Integrate science and policy, close institutional gaps
  7. Publicize the proposed plan, solicit reaction
  8. Implement the plan
  9. Develop education programs
  10. Conduct post-drought evaluation.

While planning for drought is essential, it may not come easily. As noted by the NDMC, there are many constraints to planning:

  • Politicians, policy makers, and the general public may lack an understanding of drought
  • In areas where drought occurs infrequently, governments may ignore drought planning, or give it a low priority
  • Governments may have inadequate financial resources
  • No single definition of drought works in all regions
  • Responsibilities are divided among many governmental jurisdictions
  • Most countries lack a unified philosophy for managing natural resources, including water
  • Policies such as disaster relief and outdated water allocation practices may actually deter good long-term natural resource management.

“One of the major impediments to drought planning is its cost. Officials may find it difficult to justify the costs of a plan, which are immediate and fixed, against the unknown costs of some future drought. But studies have shown that crisis-oriented drought response efforts have been largely ineffective, poorly coordinated, untimely, and inefficient in terms of resources allocated.”