River Basin Management Flashcards
(a) Explain the human and physical factors which need to be considered when selecting a site for a major dam and its associated reservoir. (5)
Physical factors that have to be considered when choosing the site of a major dam include, a site of impermeable rock e.g. granite in order to stop the water from escaping below the reservoir. Also, a narrow valley keeps the cost of management low and keeps evaporation rates low. A deep valley also is ideal as to hold as much water as possible for a successful water control project. Furthermore, without the risk of subsidence or earthquakes. There has to be a good water supply with high drainage density and reliable precipitation and/or snowmelt. The human factors that have to be taken into consideration include, a low population so relocation is not too disruptive or costly. Also, there must be no areas of cultural or historical significance as they may be destroyed. Furthermore, it should be an area of poorer farmland where compensation to farmers is kept to minimum. Also, close to agricultural areas so irrigation can be improved.
(b) Explain the positive and negative impacts, socially, of a dam you have studied.
An area of water management I have studied is the Colorado. It has been dammed in several locations which has led to positive and negative impacts. Firstly, there are many social benefits, there is less disease e.g. diarrhoea and poor health due to a better water supply. There is a better standard of living because residents can have air conditioning and swimming pools. It also allows for a growing population to be supported e.g. Las Vegas, Phoenix, 40 million people drink Colorado water. Furthermore, it supports better recreation which leads to fitter and healthier residents. However, there are some issues such as water borne disease can increase and lost healthcare money e.g. schistosomiasis. Native tribe people have to be moved from this area and resettled elsewhere, this has led to conflict with burial grounds being flooded. Communities were also forced to split apart, destroying the traditional way of life and flooding valuable flooding.
(b) Explain the positive and negative impacts, politically of a dam you have studied.
There are many political benefits of water control projects. Firstly, it encourages cooperation and partnership between the 7 states and Mexico. This is beneficial as the cost of the dam can be shared as well as the maintenance. It can also prevent civil unrest due to the positive relationship and permanent linkages provided by the dam. However, it can also lead to many issues as there can be disagreement on the allocation of the water resource; Mexico is angry it does not receive a larger proportion of the water, and the water it does receive is of a higher quality. Furthermore, the complex that is required does not take into account the changing levels of water and the reduced flow, sometimes experience drought. Lastly, there has been much dispute over the salinity of the Colorado. A desalination plant was built at Yuma to purify the water but this still causes conflict with Mexico.
(b) Explain the positive and negative impacts, economically,of a dam you have studied.
There are many economic benefits. Firstly, there are improved yields in farming due to double cropping, the introduction of cash crops as well as food surplus. Moreover, usable land increases due to irrigation allowing output to increase. This, can lead to an increase in employment in other areas such as tourism, fishing, construction and farming which means the government receives more cash to tax. However, there can also be issues firstly, when jobs are created they often do not go to locals, rather multinational companies outsource and bring in their own employees who do not remain in the area when the project is finished. Furthermore, some of the historical sites that have been flooded actually lead to a decline in tourism so some areas get richer and some areas get poorer. Also, communication routes can be disturbed during construction which discourages tourists from the area; this can impact on local business as the lose trade as there is less footfall.
(b) Explain the positive and negative impacts, environmentally of a dam you have studied.
There are many environmental benefits to water control. Firstly, fresh water supply is increased and damage from flooding declines this benefits the habitats of animals and fish in the river. Furthermore, new habitats have been created which allows new species to survive this increases biodiversity and tourism numbers. However, there are many issues, firstly water pollution increases from industries such as farming, when pesticides and fertilisers find their way into the river system. This can damage fish in the river. Moreover, the silting of the reservoirs increases as the natural flow is disturbed. The silt settles into the reservoir and builds up. This is a negative, as silt is good for farming and it’s no longer being distributed. It also reduces the capacity of the reservoir as less water is stored. Also, many species are destroyed during the build or had their habitat permanently changed, which can also lead to micro climate change and the hydrological cycle being altered.
