Impacts on host countries Job vacancies and skills gaps can be filled.
Alternatives to mitigate the negative impacts of irrigation projects The expansion and intensification of agriculture made possible by irrigation has the potential for causing: Poor water quality below an irrigation project may render the water unfit for other users, harm aquatic species and, because of high nutrient content, result in aquatic weed growth that obstructs waterways and has health, navigation and ecological consequences.
Elimination of dry season die-back and the creation of a more humid microclimate may result in an increase of agricultural pests an plant diseases. Large irrigation projects which impound or divert river water have the potential to cause major environmental disturbances, resulting from changes in the hydrology and limnology of river basins.
Reducing the river flow changes flood plain land use and ecology and can cause salt water intrusion in the river and into the groundwater of adjacent lands.
Diversion of water through irrigation further reduces the water supply for downstream users, including municipalities, industries and agriculture. A reduction in river base flow also decreases the dilution of municipal and industrial wastes added downstream, posing pollution and health hazards.
The potential direct negative environmental impacts of the use of groundwater for irrigation arise from over-extraction withdrawing water in excess of the recharge rate.
This can result in the lowering of the water table, land subsidence, decreased water quality and saltwater intrusion in coastal areas.
Upstream land uses affect the quality of water entering the irrigation area, particularly the sediment content for example from agriculture-induced erosion and chemical composition for example from agricultural and industrial pollutants.
Use of river water with a large sediment load may result in canal clogging. The potential negative environmental impacts of most large irrigation projects described more in detail below include: Waterlogging and salinization About 2 to 3 million ha are going out of production worldwide each year due to salinity problems.
On irrigated land salinization is the major cause of land being lost to production and is one of the most prolific adverse environmental impacts associated with irrigation.
However, very limited research has yet been conducted to quantify the economic impact of irrigation induced salinization. Quantitative measurements have generally been limited to the amount of land affected or abandoned.
Especially the arid and semi-arid areas have extensive salinity problems. Waterlogging and salinization of soils are common problems associated with surface irrigation.
Waterlogging results primarily from inadequate drainage and over-irrigation and, to a lesser extent, from seepage from canals and ditches. Waterlogging concentrates salts, drawn up from lower in the soil profile, in the plants' rooting zone.
Alkalization, the build-up of sodium in soils, is a particularly detrimental form of salinization which is difficult to rectify. Irrigation-induced salinity can arise as a result of the use of any irrigation water, irrigation of saline soils, and rising levels of saline groundwater combined with inadequate leaching.
When surface water or groundwater containing mineral salts is used for irrigating crops, salts are carried out into the root zone. In the process of evapotranspiration, the salt is left behind in the soil, since the amount taken up by plants and removed at harvest is quite negligible.
The more arid the region, the larger is the quantity of irrigation water and, consequently, the salts applied, and the smaller is the quantity of rainfall that is available to leach away the accumulating salts.
Excess salinity within the root zone reduces plant growth due to increasing energy that the plant must expend to acquire water from the soil.
The tolerance of crops to salinity is variable: Irrigation-related salinity has adverse effects not only on the production areas, but also on areas and people downstream.
The rivers, particularly in arid zones tend to become progressively more saline from their headwaters to their mouths. The aquifers interrelated with the river are highly saline and the salts discharged to the river system from saline aquifers adversely affect downstream water users, particularly irrigated agriculture and, in some special cases, wildlife.
Many of the soil-related problems could be minimised by installing adequate drainage systems. In Egypt, for example, the installation of drainage systems effectively reduced soil salinity. Similarly, the yield for maize increased from 2.
Drainage is a critical element of irrigation projects, that however still too often is poorly planned and managed. Waterlogging can also be reduced or minimized, in some cases, by using micro-irrigation which applies water more precisely and can more easily limit quantities to no more than the crops needs.
Water-borne and water-related diseases Water-borne or water-related diseases are commonly associated with the introduction of irrigation. The diseases most directly linked with irrigation are malaria, bilharzia schistosomiasis and river blindness onchocerciasiswhose vectors proliferate in the irrigation waters.
Other irrigation-related health risks include those associated with increased use of agrochemicals, deterioration of water quality, and increased population pressure in the area. The reuse of wastewater for irrigation has the potential, depending on the extent of treatment, of transmitting communicable diseases.
The population groups at risk include agricultural workers, consumers of crops and meat from the wastewater-irrigated fields, and people living nearby.
Sprinkler irrigation poses an additional risk through the potential dispersal of pathogens through the air. The risk that one or more of the above diseases is introduced or has an increased impact is most likely in irrigation schemes where : Malaria Malaria is by far the most important disease, both in terms of the number of people annually infected, and whose quality of life and working capacity are reduced, and in terms of deaths.Without the development of these attitudes and skills, individuals will not be well prepared to acquire the new knowledge and skills necessary for successful adaptation to changing circumstances.
Positive & Negative Effects of Colonialism Beginning in the 16th century, European powers such as Great Britain and Spain controlled and exploited far-flung territories by colonizing them. This rush to conquer and dominate land and resources uprooted and disrupted the lives of . Discuss the negative and positive aspects of the development of agriculture.
Was it, or was it not the worst mistake in the history of the human race? Agriculture is not just a way of growing food; it involves in whole spectrum of cultural changes and adaptations by early human communities/5(1). The modern agricultural system has both positive and negative impacts on our environment and ecosystem.
(ii) Food becomes more affordable to the consumer as it costs less to produce. (iv) The preservation of existing areas of woodland and rain forest habitats (and the ecosystems and other.
A Class of Distinction -- page 2: These and other aspects of economic entomology will be our main emphasis in the final section of this course when we focus entirely on insect pests and the tactics used to control them.
But despite the tremendous economic losses they may cause, it is not entirely fair to cast the members of Class Insecta as. The positive effects are surely celebrated by one and all. But the negative effects are not conducive to a healthy society.
Here, we will try to understand how media influences us negatively.