Activity
14.7
Many municipal corporations are trying
water-harvesting techniques to
improve the availability of water.
Find out what these techniques are and
how they would increase the water that
is available for use.
Answers
Answer:
Water harvesting techniques are alternative by which the water resources can be maintained to
cope with the sustainable use of water resources in catchments area. We reviewed experiences
of Indonesia in managing water resources in some of catchments area to come up with the
recommendation of best practices of water resources management in general and particularly
water harvesting techniques. Despite the available fresh water (15,500 m3 capita-1 year-1) is
more than double of the world available fresh water (600 m3 capita-1 year-1), but its distribution
is varies. In Java Island for example, where the population reaches to a number of 65% of the
total population of Indonesia, but the water only available for 4.5% of the total national water
availability. The fact that the available water of about 30,569.2 million m3 year-1 in Java are not
enough to cover the need and will be a deficit water in this island at least till 2015. The
available water is also fluctuated during wet and dry seasons. For instance, the flow of
Cimanuk River (West Java) is recorded as much as 600 m3
second-1 during the wet season, but
only 20 m3 second-1 in the dry season. How to manage water in the area with water surplus and
deficit is a crucial question to be answer. Water harvesting is becoming very important to cope
with sustainable management of water resources. There are different techniques of water
harvesting that have been successfully applied as part of water resources management in
catchments area in Indonesia. Channel reservoir, on-farm reservoir or “Embung”, infiltration
ditches, infiltration well, water harvesting dikes, etc. Channel reservoir with cascade system is
one of many rainfall and runoff harvesting techniques, which has been proven to be an
effective method to reduce peak runoff, extend the time response to runoff generation and to
some extend to increase available water for irrigation during the dry season. In Cibogo micro
catchment in West Java for example, river flow can be reduced as much as 63% after
construction of 2 channel reservoirs with cashcade system and also delay response time of the
river flow up to 1 hour. This two important points are very significant to reduce the risk of
flood in the down stream areas where the cities are generally situated. On-farm reservoir has
also been applied by farmers for supporting their farming to extend cropping. Other water
harvesting techniques such as infiltration ditches, infiltration wells, dams, water harvestinmg
dikes etc
Answer:
Water harvesting helps to increase the level of ground water by increasing the absorption and seepage of rain water into the ground.
This helps meet some supply of water for the municipal corporations which are pressurized by excess demand and dwindling supply of ground water.