Drought is a natural hazard that doesn’t come suddenly, like floods, tornadoes, earthquakes, or other natural disasters. It starts slowly, as a result of climate changes and human actions (deforestation, soil erosion due to poor farming practices, excessive irrigation) and evolves over a period of weeks, months, or even years. It usually affects a large region and has a major impact on environment and agriculture. Preparedness and drought mitigation (or relief) can reduce the effects of prolonged drought spells.
Almost every state in the United States has a drought mitigation plan. The exceptions are the states abundant in water and precipitation, like: Vermont, Michigan, Wisconsin, Louisiana, Mississippi, and Alabama. The main goal is to preserve essential public services and minimize the adverse effects of a low water supply on public health and safety, economic activity and environmental resources.
The best drought mitigation plan should consist of the following:
– Prediction – Monitoring – Impact assessment
Prediction is a result of weather and climate change studies. It includes surveying of snow packs, circulation patterns in the ocean and atmosphere, soil moisture, and assessing amounts of stored water available for emergency uses.
Monitoring involves measuring the precipitation, crop conditions, and water availability. Besides the ground monitoring systems there are also satellite monitors that provide data of wide area coverage.
Impact assessment depends on type of the land usage, presence of drought conditions, population, infrastructure, intensity and impact of the drought on farming, water quantity and quality, etc.
Response includes continuous drought monitoring, better water and crop management, increasing water supplies, increasing awareness and education, local planning, restricting of water usage, etc.
Drought preparation and mitigation strategies can be achieved by soil and water conservation and farm animal management.
Soil conservation can reduce erosion and degradation, surface runoff, and water pollution. It involves several practices to improve soil’s structure and natural biodiversity: – Crop rotation helps to control pests and diseases that often happen when one species is continuously cropped. It also increases the fertility of the soil and prevents erosion. The main goal of crop rotation is to replenish nitrogen and organic matter through the use of green manure (crop grown for the sole purpose of adding nutrients to the soil). It also allows farmers to plant crops that require less watering.
– Contouring farmland, like making ridges, basins, terraces, trenches and stone walls. These features are to prevent soil erosion and to direct any water runoff into other crop areas.
– Tillage and mulching allows water to soak into the soil and prevents the soil form drying out too quickly.
Water conservation practices are designed not only to reduce water usage, but also to protect it from pollution, increase harvesting and storage for emergency usage. The basic goal is to achieve lasting, long-term improvement in water use efficiency. Typical strategies include:
– Harvesting rainwater by collecting and storing rainwater for immediate or later use.
– Recycling water involves treating and purifying wastewater for reuse.
– Building percolation ponds for storing water for livestock and irrigation. They can be constructed by excavating a small reservoir or by building a barrier around a natural ravine or gully.
– Transvasement, by building aquaducts, which are systems of pipes, ditches, canals, tunnels, and other structures used for redirecting river water to drought-prone areas.
– Implementing water restrictions for residential and business areas. It usually involves regulations designed to reduce wasting water and improving efficiency in the use of water, for example regulating the use of sprinklers, or hoses to water yards and gardens, restricting the washing of motor vehicles or other outdoor hard surfaces like driveways, and also the fitting of water conservation devices at home, like low flow shower heads, water efficient toilet tanks, etc.
Farm animal herd management is also an important strategy for drought mitigation, as a large part of our food supply come from farm animals. The management practices include:
– Reduction in herd numbers. Evaluate all the animals and eliminate those less useful by either selling them or relocating to pastures not affected by drought.
– Early weaning of calves. A cow requires extra water to provide milk for its calf, therefore it is recommended to wean calves that are over three months old. Many farmers learned that calves over three months of age will survive on grain and Lucerne hay or molasses and protein meal diets. – Parasite control. During drought animals’ immune systems weaken and can be less resistant to parasites.
– Control of water supplies to prevent contamination. Contaminated water holes have to be fenced off to prevent animal poisoning.
When prolonged drought causes the emergency water supply to deplete, more radical approach may be required. There are a couple of strategies that can be undertaken if water supplies run short. They are: cloud seeding and desalination of sea water.
– Cloud seeding is an attempt to change the amount or type of precipitation, by releasing chemical substances into the air. The chemicals, which include silver iodine and dry ice (frozen carbon dioxide) can be dispersed by aircraft, or by dispersion devices located on the ground. They alter the micro-physical processes within the cloud that speed up condensation. The goal is to increase precipitation. There are some objections to cloud seeding, as it does not always produce positive results. First of all, the success of cloud seeding depends on several weather conditions, like the presence of cumulus clouds, certain wind speed and its direction, terrain, etc. Secondly, chemicals that have been used, like silver iodine, are toxic in large amounts, and prolonged exposure can be harmful. There have been studies showing that the amounts of silver iodine used for cloud seeding aren’t large enough and have no toxic impact, but the debate isn’t over.
– Desalination of sea water is a process of removing salt form water to make it suitable for consumption or irrigation. It has been used widely on ships and submarines. However, desalination on a large scale is very expensive. It uses large amounts of energy and specialized equipment. Many Middle Eastern countries, having large energy reserves and constant water shortages, have constructed several desalination plants. In 2007 desalination in this region accounted for close to 75% of total world capacity.
Many countries started to implement their drought mitigation plans as the drought hazard is becoming both more frequent and more severe on all continents. In the future, regional and multi-country cooperation may be required to handle this problem to create long term plans.