STORM WATER DRAINAGE SCHEME, CHURU
Most of the towns in the desert state of Rajasthan are either facing acute shortage of water or experiencing water logging and flooding. To solve the severe drainage problem in Churu, Bhan proposes an Ecological solution.
To solve the drainage problem in the district town of Churu in northern Rajasthan the state public health engineering department submitted a proposal to HUDCO to pump out the excess water onto the sand dunes. The project was estimated to cost 2.5 crores with heavy recurring cost on running and maintaining the pumps. The matter was referred by HUDCO to Ravindra Bhan, a landscape architect with specialization in ecology, to appraise the project. Using the principles of applied ecology, Bhan has evolved a scheme which will avoid any pumping and lead to creation of an attractive recreational water body in the desert town and at half the cost.
This scheme mainly envisages to provide a drainage arrangement for Churu town to drain out rain water during rainfall. However, provision has also been made to drain out sullage water shall find its way into drain system till a sewage system is provided in the town.
Churu is ana important town situated in the North-East part of Rjasthan. It was established in the early 17th century around a citadel. Earlier, it was a part of earstwhile Bikaner state. On the merger of Bikaner state into the united states of greater Rajasthan in the year 1949, Churu became a separate district with its headquarters at Churu. The name Churu is said to be derived after a jat named Chuhura, who founded it perhaps in 1620 A.D.
Churu town is located in the eastern part of the ‘Thar Desert’ at the latitude of 28°18’N and longitude 74°48’E at a height of 286m from mean sea level.
The climate of Churu town is hot and arid with large variation in temperature. Rainfall is scanty. The average temperature variation in summers and winters are 37.54°C to 24.9°C and 29.05°C to 9.15°C respectively. The maximum and minimum temperatures recorded are 47.2°C in summer and 4.4°C in winter. The period from July to mid-September is the South-West monsoon season recording an annual rainfall of 377mm. Churu also experience occasionally post monsoon season storms or depressions. Dust storms and thunder storms occur in the hot season. Mean humidity is 60%. The predominant wind direction is west and south west.
The entire population had been living in the walled city by the beginning of the century. The upper class used to live near the Fort that is core of the town and lower classes on the fringee. The fort was the nucleous of development and roads leading from Fort in south and west directions were the access of development of the old town. Thus main market came up along these two roads. The Fort is situated on the high ground. But with the growth of the town, population settled on the outskirts almost in all directions whereas, the present trend of growth is in the south west, west and north west directions. The town itself has developed in the area full of sand dunes and in surrounded on three sides by high sand dunes. On the southern side, these exist shifting sand dunes. The pockets available in between the roads and sand dunes were developed into residential colonies and other public buildings.
NECESSITY OF THE SCHEME:
In absence of proper drainage system, it becomes a problem to drain out rain water during rainy season and dry weather flow from the in habitat areas of the towns. The rain and waste water remains stagnant for quite a long time in the low lying areas and cause hardship to the inhabitants as well develop unhygienic condition. The condition of the fringe localities is awfully bad as these areas are not even provided with pucca side drains. The following are the few areas where dry weather flow as well as storm water presently gets collected.
Keeping the existing conditions of the town in view, it has become necessary to provide a system which may drain out rain water and sullage water from the worst affected areas of the town.
EXISTING DRAINAGE PROJECT
The topography of the town is quite undulating and it is evident from the contour map that the natural drainage of the town area of Municipal limit is not possible. A few residential localities settled around the Fort have pucca side drains, though there are inadequate to take care of storm water. The sullage and rain water from more than half of the developed town including main marketing centre gets collected into Johri Sagar near Bagla School, from where it is pumped into the low lying area existing in the west direction of Johri Sagar. This system is hardly sufficient to deal with the daily dry weather flow, collecting in Johri Sagar. Besides, the holding capacity of the area, where waste water is being pumped presently, is meager. The other parts of the town do not have any sort of drainage system and waste water coming out from houses gets collected in localized low lying areas.
PROPOSED DRAINAGE SCHEME:
To have the idea of natural slopes of streets etc. the complete town was surveyed and levels were taken with respect to assumed B.M., adopted as top of the rail line in front of exit gate of Railway Station. The reduced level of top of the rail was taken as 286.205m. With the help of spot levels taken in the entire town, contour map was prepared. Looking to the different ridge lines, the worst affected area was divided in two zones, namely-Johri Sagar zone and stadium zone, which are also termed as Zone A and Zone B respectively. Looking to the topography, it is not possible to drain out water with gravity flow anywhere. Out of the municipal limit, in the circumstances there is no option left to provide pumping arrangement separately for each zone to pump out rain water and sullage water. Disposal site for Zone-A has been selected in north direction about 2 Kms away from Johrisagar near NathjikaDhora. For Zone-B, the disposal site has been selected in west direction about 2.5 Kms away from stadium.
Rectangular masonry main drains suitable for carrying rain water for 12mm per hour rainfall intensity have been proposed along the feasible alignment as shown in the map in both the zones. Provisions has also been made for construction of small drains in the side streets wherever required as per Municipal council practice. Wherever it was considered open drain to be unsuitable due to high depths, circular R.C.C. non-pressure pipes with manhole chambers at suitable spacing, have been proposed.
Pumping stations for Zone-A and Zone-B are proposed to be located near JohriSagar and Stadium. Each pumping station shall constitute a screen chamber, sump well, pump room etc. The pumping sets for rain water as well as sullage water shall be installed in the common pump room. From the pumping station, parallel pumping mains are proposed to be laid up to the highest point available in the alignment towards disposal sites. From the tail end of the pumping main, an open masonry drains are proposed to be constructed up to disposal sites.
Provision has also been made for trolley mounted diesel engine driven pumping sets to pump out rain water from the localized depressions not covered under Zone-A and B. Likewise, provision has also been made for a tractor with tanker fitted with a pump set to pump out daily sullage flow from the blocks of houses situated in the fringe of town.