Flow of water in Kanke Dam has also reduced
Water reduced in one of the important ponds of Ranchi city.
This summer season most of the ponds and small rivulets flowing through the city has dried up due to unbearable hot temperature. Earlier Ranchi was known for its cool climate even in the summer season. Temperature rarely went up to 41 degree centigrade. But now it is very common. It is a fact that before 1990s whenever temperature rose to 35 degree centigrade during day time, Ranchi plateau used to get evening rainfall which helped to recharge the ground water table as well as surface water table. But now this phenomenon has stopped. Now continuous dry season last for more than six months. From last few years the temperature is showing increasing trend.
The main reasons for this water scarcity are as follows:
Dams: There are three major dams (Kanke, Rukka and Hatia) in Ranchi city which is now filled with sediments affecting water table. Due to these sedimentations the storage capacity of all the three dams have decreased many fold. From the year of their constructions silts have never been removed which has not only depleted the water table but also made dame water contaminated.
Topography: General elevation of Ranchi city is 600 m. above the mean sea level and has a flat to gently undulating topography with occasional ridges. The Ranchi plateau gradually slopes down towards south east into the hilly and undulating region of Singhbhum. Due to this uneven topography the rain water are lost through surface runoff resulting in less water percolation below the surface. The thin soil layer of Ranchi plateau which is becoming more thin due to weathering is gradually loosing its water retaining capacity.
Geology and Urbanisation: The process of urbanization and industrilisation from last 20 years has caused changes in the water table as a result of decreased recharge and increased withdrawal. Many of the small ponds which were main source of water in the surrounding areas are now filled for different construction purpose affecting the water table. Lots of DEEP- BORING in the Ranchi city has also forced the water table to move down as well as Ranchi plateau consists of metamorphic rocks which are relatively impermeable and hence serve as poor aquifers. They bear groundwater only in their weathered top portion which rarely exceeds 10 meters.
Rainfall factor: Though Ranchi receives sufficient amount of rainfall (1000mm to 1200 mm every year) but it is not an accurate indicator of groundwater level changes. Recharge is the governing factor (assuming annual withdrawals are constant); it depends on rainfall intensity and distribution and amount of surface runoff. As Ranchi is the plateau area waste of rainwater in the form of surface runoff varies from 35% to 40%. So recharging is not so good.
Many houses have been built over the recharge area which are the major source of water to unconfined aquifer below, because an unconfined aquifer is one in which a water table varies, depending on areas of recharge and discharge and pumping from the wells.
Among the natural drinking water sources are ponds and lakes that too has their life span, is being threatened by early Eutrophication due to sedimentation, which hampers bottom discharge processes. Pollution growth of Algal bloom, weeds in the remaining ponds of Ranchi has made water unfit for domestic use imparting fowl smell.
The state of Jharkhand, although claims to be a store house of minerals in India, is not so rich in water resources. Most of the areas are occupied by the hard rock, which is in general protracted drought prone areas.
Hard rock which occupies major portion of the Jharkhand plateaus are devoid of primary porosity and occurrence and movement of groundwater is controlled by the joints, fractures and fissures present in them.
The need of the day is to conserve every drop of water and recharge the depleted aquifers. Mere slogan shouting will not carry us far. The time is now ripe for action with the involvement of the people who are beneficiaries.
Half- hearted attempts are being made at rainwater harvesting in Ranchi city and with much publicity given in the media. The scheme can benefit thousands of acres of arid lands, if small ponds are excavated at vantage points or small check dams are build in at particular intervals in the different rivulets to conserve soil moisture.
1. Identification of the recharge area or catchment areas in and around Ranchi city to ensure no further construction on those lands.
2. Construction of artificial water reservoirs in suitable area in and around Ranchi to collect the rain waters.
3. Cleaning of ponds, lakes, rivulets and dams periodically to rejuvenate their capacity of storage of water.
4. Providing proper consultancy to determine suitable areas for deep boring and hand pumps.
5. To ensure regular safe drinking water supply from the Municipal to stop reckless deep boring, because in absence of water supply people are forced go for alternative source of drinking water.
6. Water conservation measures from domestic level.
7. Metering and pricing of water.
8. Region wise, in-depth study of the water balance.
9. Further planning of plantation and aforestation to ensure regularity of water cycle.
10. Fostering an awareness of water as a scare resource and its conservation as an important principle-through NGOs.