Drought events are one of New Zealand's most costly natural hazards and have a significant impact on agricultural production.
Experts generally agree that climate change is affecting New Zealand’s weather patterns. In Taranaki, rainfall is predicted to decrease in summer and increase in winter. South Taranaki is predicted to become drier on average, with more frequent droughts.
A drought is a sustained period of low rainfall so that soil moisture is insufficient for plant growth. This can lead to the ground drying up, and can also reduce the volume of water in rivers/streams, lakes/dams and subterranean reservoirs. Drought occurs over an extended period of time, usually a season or more. The onset of drought can be slow and may go unrecognised for some time.
A drought can be defined as an:
- 'Agricultural drought' where there is soil moisture deficit which impacts on agricultural and horticultural industries, and / or
- 'Hydrological' which results in a water supply shortage.
Crops, including pasture, rely on moisture within the soil to survive. During an agricultural drought, soil moisture becomes so low that plants become stressed and if the drought is prolonged, they will die. An agricultural drought ends when adequate amounts of rain restore soil moisture levels.
The effects of an agricultural drought can include:
- Crop failure and lack of stock feed
- Lower production
- Economic loss locally and regionally
- Poor stock condition and lower reproductive performance
- Psychological and social issues in farming communities
- Increased number and severity of rural fires
- Water shortages leading to restrictions on irrigation.
The main impact of a drought is often on agriculture. The Ministry for Primary Industries will declare when a dry period is classed as a drought.
A Hydrological drought is where there is a significant reduction in the amount of water available in rivers, lakes and groundwater. This type of drought occurs when rainfall is well below expected levels in any large catchment area for an extended period. Water supply droughts droughts can result in water supply shortages.
Droughts affect activities such as agriculture and power generation, and can have flow-on effects to other sectors of the community. Some of the more severe impacts of a drought include:
- Damage to plants and animals, wildlife habitat, and air and water quality
- Forest fires leading to a reduced landscape quality
- Insect infestations and plant disease
- Loss of biodiversity and soil erosion.
- Public safety and health
- Conflicts between water users
- Inequities in the distribution of impacts and drought relief.
- Economic impacts occur in agriculture and related sectors
- Losses in yields in both crop and livestock production
- Increase in the number of forest fires
- Reduced income for farmers and retailers and others who provide goods and services to farmers
- Increased prices for food, energy and other products as supplies are reduced.