Study on feasibility of drip irrigation in shallow ground water zones of eastern India
Although the effectiveness and economics of drip irrigation systems are well established in areas having undulating topography and water scarcity, its economics in plain areas bestowed with good quality ground water at shallow depths are not yet studied. Due to this, there is confusion among farmers as well as planners regarding the guidelines for selection and propagation of this system in such areas. This study attempts to evolve guidelines for deciding the economic threshold value of fixed cost of drip irrigation system for sugarcane crop. Nomographs have been developed to find the threshold value of economic fixed cost of drip irrigation system (exclusive of pumping unit) for a combination of variables, depth of water table, yield level under check basin irrigation, expected yield gain with adoption of drip system, irrigation requirement with check basin, and electricity charges. The perusal of nomographs shows that the factors influencing the economics of drip irrigation in order of importance are yield gain ratio, electricity charges, irrigation requirement and depth of ground water.
Realizing the potential: using pumps to enhance productivity in the Eastern Indo- Gangetic Plains
Eastern Indo-Gangetic Plain (EIGP) comprising of eastern Uttar Pradesh, Bihar and West Bengal in India, Nepal tarai and plains of Bangladesh, though endowed with rich water resources has very low produtivity. This region is characterized as “High potential low productivity” area. Though, the ground water development in the region has increased substantially during the last decade (19.2% and 24.2% in 1993 to 33.2 and 32.2% in 1998, respectively in the two states of Bihar and West Bengal) its utilization is poor owing mainly to improper irrigation scheduling and selection of pumps and poor pump efficiencies, unreliable energy supply, and lack of information to users. The tail reaches in most of the canal command also depend on groundwater irrigation. Pump is the predominant device used for lifting of groundwater. In the past two to three decades, pump technology has been spreading rapidly resulting in crucial transformation of the irrigated agriculture in areas such as EIGP that previously had been unable to take full advantage of the “green revolution” technology due to lack of irrigation water. The recent adoption of pump technology was far more rapid in Bangladesh, but much slower in Bihar and Nepal tarai. Density of the pumping unit in the eastern region (around 105 pumps / thousand ha) is far low as compared to agriculturally developed states–such as Punjab (225 pumps / thousand ha in 1993-94) and Haryana (148 pumps/thousand ha). This not only resulted in under utilization of ground water but also poor realization of benefits from the groundwater. Small and highly fragmented land holdings, unreliable / erratic energy supplies, poor economic conditions and lack of infrastructure facilities are some of the reasons for under utilization of groundwater. In the EIGP, use of diesel operated pumps is predominant, as more than 90% of the pumps are diesel operated. Efficiency of pumping units is also a serious concern. Small and cost effective interventions, e.g. improvement in fittings and foot / reflux valves, can substantially increase pump efficiency. Conjunctive use of groundwater in canal command has been demonstrated to enhance the crop yields under rice-wheat system by more than two folds and encourage groundwater utilization. Groundwater market is another opportunity, which needs to be explored in large scale to provide irrigation facilities to small farm holders who can not afford tube wells/shallow tube wells and/or find it uneconomical to own it. Groundwater markets have grown in Bangladesh, West Bengal, in parts of eastern U.P. and North Bihar to a certain extent. There are also evidences to support the concept and functioning of community/group tube Using Pumps to Enhance Productivity in the Eastern IGP 201 wells operated by groups of small and marginal farmers in backward regions of eastern U.P. (Deoria) and north Bihar (Vaishali). The paper presents a brief description of various efforts made to enhance productivity in the EIGP together with challenges in groundwater management including cost effective and energy efficient technologies and participatory on-farm water management.
Full-scale measurements of SO2 gas phase concentrations and slurry compositions in a wet flue gas desulphurisation spray absorber
Abstract Two measurement campaigns were carried out at ENERGI E2's Asnaes Power plant, unit 5. The unit has a capacity of 620 MW e and is equipped with a wet flue gas desulphurisation (FGD) plant employing a counter-current spray absorber with five spray levels. In the first campaign, the power plant was firing Orimulsion ® with 2.85 wt% S resulting in a flue gas concentration of SO 2 exceeding 2000 ppmv. In the second campaign, the fuel applied was a low-S blended coal and the SO 2 concentration in the raw gas was around 400 ppmv. A novel probe for in situ sampling of gas phase concentrations in wet FGD spray absorbers was developed and applied for measuring axial profiles of the SO 2 gas phase concentrations in the absorber. The expected decrease in SO 2 concentrations along the height of the absorber was found in the spray section (from height 26.5 to 36.2 m) whereas the SO 2 concentration above the holding tank and below the gas inlet was quite low probably due to long local residence times in the region. Horizontal variations, due to somewhat different flow conditions near the column wall were investigated and the SO 2 concentrations were found to be higher near the wall. Measurements at different gross loads showed that the SO 2 gas phase concentration at a given position inside the absorber was roughly linearly related to the L/G ratio in the measuring interval. Turning off one of the lower spray levels, while burning coal with low S content, did not lower the overall removal efficiency of the absorber. However, the SO 2 gas phase concentration inside the lower part of the absorber was increased by a factor of 2–3. Measurements of slurry pH at different positions showed a decrease of approximately 0.5 units from the upper to the lower part of the absorber. The full-scale measurements provide a detailed set of experimental data for validation of mathematical models of a wet FGD spray absorber.