Irrigation, sometimes referred to as an irrigation scheme, is the act of redirecting water for a specific purpose. This purpose is usually to water agricultural crops, to maintain landscapes, or to provide much needed water during a drought. Less often, irrigation is used to control dust, to get rid of sewage, and to aid in mining projects. This article takes a closer look at the environmental impact of irrigation.
Because irrigation systems deal with redirecting water from rivers, lakes, and underground sources, they have a direct impact on the surrounding environment. Some of these impacts include: increased groundwater level in irrigated areas, decreased water flow downstream of sourced rivers and streams, and increased evaporation in irrigated areas.
Increased evaporation in irrigated areas can cause instability in the atmosphere, as well as increase levels of rainfall downwind of the irrigation. These changes to the climate are a direct result of changes to natural moisture levels in the surrounding atmosphere. Irrigation systems also have an indirect impact on the surrounding environment.
The effects of irrigation on water table, soil salinity and salinity of drainage and groundwater, and the effects of mitigation measures can be simulated and predicted using agro-hydro-salinity models.
As a hydrological result it is found that: the downstream river discharge is reduced the evaporation in the scheme is increased the groundwater recharge in the scheme is increased the level of the water table rises the drainage flow is increased These may be called direct effects.
In the cropping situation, irrigation can be used to help establish crops if there is insufficient soil moisture for germination and growth. Earlier establishment of crops in the autumn not only reduces the risk of water or wind erosion and the subsequent loss of phosphorus in sediments, but it also means the crop has established prior to the winter.
Early establishment means earlier development of an extensive root system and more plant dry matter bigger plants , factors which result in increased plant uptake of nitrogen, which would otherwise have been susceptible to leaching, from the soil profile. It is acknowledged that not all irrigation is benefiting the environment, but instead of constantly criticising irrigation as damaging the environment we should also be celebrating its benefits to the environment.
The next step is to look at improving the poor irrigation practices and determining how we can efficiently irrigate more land in high risk areas, such as the Ruataniwha and the Wairarapa, to benefit the New Zealand economy and the environment. Alongside good scientific data that illustrates the benefits of irrigation, we also need good scientific data that demonstrates its negative impacts, so these impacts can be addressed.
Leveled by. Monday, May 11, At each stage, innovations in farming techniques brought about huge increases in crop yields by area of arable land. This tremendous rise in food production has sustained a global population that has quadrupled in size over the span of one century.
As the human population continues to grow, so too has the amount of space dedicated to feeding it. According to World Bank figures, in , more than million hectares 1. In the coming decades, however, meeting the demand for accelerated agricultural productivity is likely to be far more difficult than it has been so far.
The reasons for this have to do with ecological factors. Global climate change is destabilizing many of the natural processes that make modern agriculture possible. Yet modern agriculture itself is also partly responsible for the crisis in sustainability. Many of the techniques and modifications on which farmers rely to boost output also harm the environment.
Below are brief descriptions of three ways intensive agriculture threatens the precarious balance of nonagricultural ecosystems. Irrigation Worldwide, agriculture accounts for 70 percent of human freshwater consumption. A great deal of this water is redirected onto cropland through irrigation schemes of varying kinds. Experts predict that to keep a growing population fed, water extraction may increase an additional 15 percent or more by Irrigation supports the large harvest yields that such a large population demands.
Researchers and farmers alike are becoming increasingly aware of the consequences of this large-scale diversion of freshwater. One of the most obvious consequences is the depletion of aquifers, river systems, and downstream ground water. However, there are a number of other negative effects related to irrigation. Areas drenched by irrigation can become waterlogged , creating soil conditions that poison plant roots through anaerobic decomposition. Where water has been diverted, soils can accrue too much salt, also harming plant growth.
Irrigation causes increases in water evaporation, impacting both surface air temperature and pressure as well as atmospheric moisture conditions.
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