Managing water supplies Flashcards
What is IWRM?
Integrated Water Resources Management aims to encourage cooperation between users of a river basin. It treats the basin holistically to ensure:
1. Water is used with maximum efficiency/
2. Water is equitably distributed
3. Water is of high quality
Important International Agreement for the use of water.
The Helsinki Rules (1996) and Berlin Rules (2004) with their ‘equitable use’ and ‘equitable shares’ concepts.
The United Nations Economic Commission for Europe (UNECE) Water Convention promotes the joint management and conservation of shared freshwater ecosystems.
The UN-Water Courses Convention offers guidelines for the protection and use of transboundary rivers
The EU Water Framework Directive (2000), commits all members to ensure the ‘status’ of their water bodies, including their marine waters up to one nautical mile from shore.
Management of the Colorado River Basin
In 1928, the use of the Colorado River was agreed between states under the Colorado Compact (also called the Law of the River). Mexico was then included in this agreement in 1944.
In 1963, The US Supreme Court renegotiated the allocation of water under the Colorado Compact to align with the falling water levels in Lake Mead, based on the percentage of available water.
However, this compact only accounted for the quantity of water rather than the quality of water. Mexico complained that increased salinity made their share of the Colorado River almost unusable. The US then spent 43000 million constructing a desalination plant at Yuma to improve water quality in Mexico. This costs $20 million per year to maintain.
Some states withdrew more water than they were allocated. California for example withdrew 6.4 cubic kilometres despite being allocated 5.4 cubic kilometres. In 2007, California was ordered by the Federal government to cut to its allocated volume by 2015.
By 2009, the level of Lake Mead was lower than any time since 1965 and had averaged 66% of expected flow since 2009.
Tensions over the Colorado are likely to increase in the future due to climate change which may result in a 10 - 30% reduction in runoff into the river. This means that the river would fail to reach its expected volume in 6 out of 10 years by 2050.
How is Nevada managing the crisis over the Colorado River?
Construction of desalination plants on the Californian coast was an option. However, 2009 estimates suggest this would’ve cost $9-10 bn to construct and $400 million per year to pump the water.
Another option was to abstract water from groundwater stores in Snake County. However this would cost $2-3 billion to supply 100,000 homes and is questionable in terms of sustainability.
Instead, the Southern Nevada Water Authority has aggressively pushed for water conservation. In 2004 it achieved its aim of 25% reduced water consumption per person between 1990 and 2010. it aims to reduce water consumption to 200 gallons per person per day by 2035 from 345 gallons per person per day in 1990. this is being done through:
50% reduction in the cost of pool covers
50% reduction in the cost of smart water garden irrigation systems
Paying $1.5 for every square foot of turf replaced with desert landscaping
$2 discount for ‘Water Smart’ car washes
Management of water supply in Singapore
Due to a lack of large sources of water (rivers lakes aquifers) Singapore has had to rely on imported water from Malaysia and the catchment of rainwater.
To increase water security, Singapore plans to increase the proportion of water used from desalination (from 10% in 2016 to 30% in 2060). Singapore also plans to increase the proportion of water used from recycled grey water (from 30% in 2016 to 55% in 2060).
Singapore plans to completely remove its reliance on imported water from Singapore by 2060 (which supplied 40% of water in 2016) and decrease its reliance on rainfall catchment - as this may change drastically in the future due to climate change - from 20% in 2016 to 15% by 2060.
Less imported water from Malaysia may lead to tension due to fewer customers thus less income from its exported water. However, it is important to remove reliance on Malaysia as they can control the price of its water exports and can control who receives it - giving Malaysia influence over Singapore.
Water management in Machakos District, Kenya
Hot and dry climates result in high evaporation rates in the dry season. This disrupts the supply of water to rural communities. To improve water security, particularly during the dry season, communities have started building sand dams which trap excess water in the wet season behind 1m tall sand walls and amongst coarse sand particles.
During the dry season, the sand stops water from evaporating. Locals can then extract trapped water by digging wells or channelling the water through the fam and tapping it off on the other side.
The sand dams are cheap to construct and use local materials. They require little maintenance and their height can be increased each year to trap more water. The area surrounding the dam is recharged allowing vegetation to grow and locals are trained by water charities on how to build dams so they can become self-sufficient.
