DESIGN AND DEVELOPMENT OF CONTROL AND REGULATORY STRUCTURES FOR OPTIMAL UTILIZATION OF SURFACE AND GROUND WATER
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Date
2019
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Indira Gandhi Krishi Vishwavidyalaya, Raipur (C.G.)
Abstract
Agricultural sector is the main consumer of our available water resources and demand of water in agricultural sector is continuously increasing. Since water resources of an area are limited, it is only possible to meet out this increasing demand by proper utilization of available water resource in an area. This study is an attempt to plan proper utilization of surface and ground water resources of farm of Raipur campus of Indira Gandhi Krishi Vishwavidyalaya, Raipur, Chhattisgarh.
Reconnaissance survey of the study area along with interactions with various stake holders helped in arriving at the problems related to water resources of the study area. The major problem surfaced out is the operation of diversion structure (Bhaari Dam) constructed on existing rivulet of the study area called “Chhokranala” at the upper portion of the farm and its diversion canal (Tar) during monsoon season and immediately after it. This results in under utilisation of available surface flows and over exploitation of precious ground water even during the dry spells in monsoon season when sufficient flows are available in the Chhokranala. Besides this during active flows in diversion canal, temporary water logging is observed during heavy rainfall in the portion of horticulture farm above the diversion canal, where water sensitive vegetable crops are cultivated.
Detail contour survey of the study area was performed and longitudinal sections and cross sections of the diversion canal and other drains were taken to know their carrying capacity. Actual discharges in them were also measured by area- velocity method. Locations of appropriate regulatory and control structures were also identified and their sizes were calculated.
Discharge carried by the diversion canal was measured as 73 lit/sec near IFS field. Longitudinal section of diversion canal clearly shows two distinct critical sections, one is the lined portion of diversion canal above IFS field (chainage 510 m to 540 m) and another is behind the office of In-charge horticulture farm (chainage 712.5 m to 742.5 m) which obstruct the desired flows and needs cutting at these sections.
Diversion canal is acting as interceptor drain for the runoff being generated from the catchment area above it and being actively drained to Chhokranala through drain no. 1, immediately below Bhaari dam, Drain no. 2, near soil science area and drain no. 7, along the air port road of horticulture farm. Drainage capacity of diversion drain and other diversion canal was calculated by considering the drainage coefficient on the basis of last 10 years highest one day rainfall. Results clearly shows that existing carrying capacity of drain no.-1, 2 and 7are sufficient to drain out the runoff water intercepted by diversion canal during heavy rainfall provided flows from Bharri dams are not diverted to it. For this purpose Head regulator is proposed and designed.
To drain out the runoff received by drain no. 6 to drain no. 4, inverted siphon is proposed below the diversion canal. Total length of the structure is 14.87 m which was divided into three different sections, first is contraction side (1.435 m long), second is expansion side (2.590 m long) and third portion called waterway (10.845 m long). In waterway section we proposed concrete pipes with diameter 0.425 m to drain out the water with designed discharge rate of 0.382 m3/sec and provided 0.65 m soil cover, which is sufficient to absorb the pressure. For draining out catchment of drain no. 5 to drain no.6, a road crossing is proposed, having concrete pipe of diameter 0.278 m and length 11 m. Soil cover of 0.30 m with concrete above it is proposed over the pipe to absorb the loads.
For optimal utilization of surface water, flow diversion structures like cross regulator, diversion box and head regulator were proposed at appropriate locations. Cross regulator was provided at three different locations L1, L2 in drain-2 and L3 in drain-7. When flow comes at full capacity of drain-2 and drain-7, for cross regulator L1, L2 and L3, height proposed is 33 m, 42 m and 41 m respectively and width proposed is 60 m, 34 m and 73 m respectively, to divert the flows to the field along drain-2 and drain-7.
The diversion box is a three way box that is used to divert water flow from the main diversion canal and distributed in other connected drains. Two diversion boxes were proposed (D-1 and D-2), one was connected to three way flows at the junction of diversion canal and drain-2 and second one was connected to two way flows at the junction of diversion canal and drain-7, when the flows comes into diversion box at the rate of 195.16 lit/sec. Dimensions of diversion box are 48, 110 and 90 cm height and 32, 10, 12 cm width respectively for first three sections of the box (D-1) and 32, 70 cm height and 32, 18 cm width respectively for two sections of second box (D-2).
Head regulator are provides at the head of canal for optimally tackle out the water from Bharri dam and used for diverting sufficient amount of water into canal for irrigation at the time of dry spells. Calculated width of 16 cm and gate opening of 74 cm is sufficient to carrying 195.16 lit/sec discharges to the diversion canal.
In watershed different components plays important role for recharging the groundwater such as rainfall, canal irrigation, bore well irrigation and ponds/tank irrigation. This is measured through rainfall data and electricity bills. Groundwater recharge by rainfall was 54,900 m3, from canal was 60,205.21 m3, from bore wells 218.56 m3 and from Tanks/Ponds was 8655.36 m3 respectively. Therefore, total recharge by different irrigation sources was 1, 37,680.13 m3.
Managing surface and groundwater (consumptive use) in the study area means to increasing use of surface water and reducing the dependency on groundwater, when sufficient surface flows are available. For this purpose three Lift Irrigation Schemes (LIS) are proposed at appropriate location at the downstream of Bharri Dam at Chhokranala (LIS-1, LIS-2 and LIS-3). Detailed survey was done and suitable low head high discharge open well submersible pumps were selected for lifting the available surface water ponded behind fisheries check dam and check dam on culvert of Airport road near horticulture farm. This water was used during dry spells in monsoon season for irrigating Kharif crops and also during crop establishment period of Rabi crops. At present, at both these stages we are using high head low discharge technology for lifting groundwater from bore wells even though sufficient flows are available in Chokranala and Bharri dam.
Design discharge capacity of LIS-1, LIS-2 and LIS-3 were worked out as 5.48 lps, 5.07 lps and 12.85 lps respectively against the total head of 43.06 meter, 39.10 meter and 32.70 meter respectively. LIS-1 and LIS-2 is designed with the provision to provide sprinkler irrigation to the Rabi crops in the establishment period and initial growth period through the flows ponded behind fisheries check dams. During Kharif season LIS-1 and LIS-2 will be providing flood irrigation which will reduce total head to 18.06 meter and 14.10 meter, resulting in increased discharges. Pump hp suggested is 5 hp for LIS-1 and LIS-2 and 7.5 hp for LIS-3. Total cost of all the three LIS has been worked out as ₹ 3, 26,680/-.
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