Drought

Canvi climàtic

RISKS DESCRIPTION

It is the persistent lack of precipitation (meteorological drought) that may lead to a reduction in the availability of surface water and groundwater for a given period of time (hydrological drought).

Climate change will lead to temperature increases and rainfall pattern variations, among other effects. Catalonia, which is already characterised by an irregular precipitation pattern and year-on-year rainfall variability, will become even more susceptible to suffering droughts in the coming years. In fact, Catalonia has already witnessed various periods of drought in recent years, the latest of which took place in 2007 and 2008. More than a year passed without significant rainfall and extremely restrictive measures had to be applied to various areas of the territory. However, the drought periods forecast for the coming decades will be longer, more frequent and more intense because the predicted reduction in precipitation will be accompanied by an increase in evapotranspiration caused by the warming of the planet. Moreover, there is also expected to be a slight increase in the demand for water (4% in the city of Barcelona).

The main effects of drought on the environment are the reduced flow of rivers and streams, decreasing levels of water in reservoirs (or even their drying out) and increases in the incidence of fires. In general, drought produces hydric stress in ecosystems, which, if intense and prolonged, may result in extremely severe effects and increase mortality. Moreover, hydric stress debilitates the vigour of flora and fauna and makes species and habitats more sensitive and vulnerable to other pressures and disturbances. A decrease in precipitation is also associated with an increase in contamination: contaminants become stagnated because they cannot be diluted in water.

The urban ecosystem, which is built on practically impermeable land, is already water deficient.

Limitations on the availability of water resources have serious effects on many ecosystems (not just fluvial ones), on urban green spaces, on the economy and on the health and wellbeing of the population. For example, the farming and livestock sector is threatened in prolonged periods of water scarcity, as is the operation of many industrial systems. A good example of this is the reduction in the production of hydroelectric energy due to periods of drought suffered in the period from 2003 to 2007, which according to the Catalan Energy Institute (ICAEN) was 40.8%, substantially increasing the price of electricity.

HEALH EFFECTS

Water is an essential resource for human beings and other organisms. The human body requires a minimum intake of water to prevent dehydration, which could lead to serious diseases, such as cancer of the urinary tracts or kidney stones, in addition to more immediate episodes like disorientation, dizziness and fainting. The quantity of water necessary varies in accordance with age, health, physical activity and weather conditions, and ranges from one to two litres per day in normal conditions (no physical activity and temperatures below 30 ºC). However, in addition to minimum consumption, according to the World Health Organization (WHO), suitable water, sewerage and hygiene services are also essential to prevent many other diseases and improve nutritional results (6). Therefore, it must be guaranteed that the entire population has access to the quantity and quality of water necessary for their wellbeing.

The effects of drought on urban green spaces may affect their ability to regulate the urban environment (temperature, noise, air quality, etc.) and by extension the health of the resident population.

OBJECTIVE

General

Mitigate the effects of drought periods to ensure that the health, hygiene and wellbeing of the population, especially the most vulnerable groups, are not jeopardised.

Specific

Guarantee the supply of potable water to meet the needs of the population.
Foster more sustainable use of water.
Minimise the effects of drought on the natural environment, especially in spaces most closely associated with people’s health.
Increase the number of high-quality urban green spaces.
Guarantee the presence and survival of urban green spaces.
Increase the permeability of urban land.

PROPOSALS AND RECOMMENDATIONS

Develop and foster other water supply infrastructure for non-sanitary uses: for example, the reuse of grey water in toilet cisterns or the use of rainwater for street cleaning.
Correctly manage water resources (rivers, streams, basins, reservoirs, aquifers and wells).
Foster water saving on the municipal scale.
Optimise and reduce water consumption in the industrial sector.
Increase urban forestry and green spaces, in addition to the permeability of the land, planting indigenous species with very low water needs and/or species adapted to periods of drought.
Plant crops that are tolerant to drought and have less demand for water, foster crop rotation and/or foster more sustainable irrigation methods.
Control water catchments in accordance with the provisions of legal regulations.
Raise people’s awareness about the correct consumption of water and foster water-saving systems.
Develop protocols to be followed in the event of severe drought with a view to not compromising the wellbeing of the most vulnerable groups (children, the elderly, the underprivileged).
Design public and urban green spaces in such a way that they are more resistant to periods of drought.
- Choose plants that can adapt to these periods and, where necessary, replace those that cannot.
- Apply gardening techniques that make better use of water (drip irrigation, mulching, etc.).