Irrigation management and its effect on productivity under Parambikulam Aliyar Project in Tamil Nadu

While at the national level, area under surface irrigation has been increasing, in Tamil Nadu, it has been declining. There is an increased reliance on groundwater sources of irrigation. This highlights the need for improving quality and reliability of canal irrigation in order to increase net irrigated area and improve water productivity in agriculture. In surface irrigation systems, where scarcity in supply is experienced, conjunctive use of groundwater helps to achieve better yield. However, in larger surface irrigation, which supplies water to dry crops – there is a need to assess the effect of conjunctive use in different segments of the command taking into account several other factors such as climatic conditions, local rainfall and sub surface geology. This is because not all parts of the command area get adequate supply, which in turn leads to poor recharge of wells. The paper looks at conjunctive use for irrigation management in the Parambikulam Aliyar Project in Tamil Nadu.Length: pp.819-840Surface irrigationGroundwaterConjunctive useWater distributionIrrigation programsIrrigation schedulingCrop management

The use and re-use of unsustainable groundwater for irrigation: A global budget

Depletion of groundwater aquifers across the globe has become a significant concern, as groundwater is an important and often unsustainable source of irrigation water. Simultaneously, the field of water resource management has seen a lively debate over the concepts and metrics used to assess the downstream re-use of agricultural runoff, with most studies focusing on surface water balances. Here, we bring these two lines of research together, recognizing that depletion of aquifers leads to large amounts of groundwater entering surface water storages and flows by way of agricultural runoff. While it is clear that groundwater users will be impacted by reductions in groundwater availability, there is a major gap in our understanding of potential impacts downstream of groundwater pumping locations. We find that the volume of unsustainable groundwater that is re-used for irrigation following runoff from agricultural systems is nearly as large as the volume initially extracted from reservoirs for irrigation. Basins in which the volume of irrigation water re-used is equal to or greater than the volume of water initially used (which is possible due to multiple re-use of the same water) contain 33 million hectares of irrigated land and are home to 1.3 billion people. Some studies have called for increasing irrigation efficiency as a solution to water shortages. We find that with 100% irrigation efficiency, global demand for unsustainable groundwater is reduced by 52%, but not eliminated. In many basins, increased irrigation efficiency leads to significantly decreased river low flows; increasing irrigation efficiency to 70% globally decreases total surface water supplies by backsim600 km3 yr−1. These findings illustrate that estimates of aquifer depletion alone underestimate the importance of unsustainable groundwater to sustaining surface water systems and irrigated agriculture

Performance evaluation of the Bhakra Irrigation System, India, using remote sensing and GIS techniques

Irrigation systems / Irrigation canals / Irrigation scheduling / Performance evaluation / Remote sensing / GIS / Irrigated farming / Satellite surveys / Sustainable agriculture / Productivity / Groundwater / Salinity / Crop yield / Wheat / Surface irrigation / India / Bhakra Irrigation System

THE EQUITY CONSEQUENCES OF PUBLIC IRRIGATION INVESTMENTS: THE CASE OF SURFACE IRRIGATION SUBSIDIES IN INDIA

This paper is organized as follows. Section 1 reviews the structure of surface irrigation charges and the trends in irrigation expenditures and revenues in India. Section 2 discusses the measurement of irrigation subsidies and the data. Section 3 examines the incidence of surface irrigation subsidies and section 4 summarizes the magnitude of these sudsidies. Section 5 elaborates the policy implications of the findings of the study.Resource /Energy Economics and Policy,

Experimental In-Field Transfer and Survival of Escherichia coli from Animal Feces to Romaine Lettuce in Salinas Valley, California.

This randomized controlled trial characterized the transfer of E. coli from animal feces and/or furrow water onto adjacent heads of lettuce during foliar irrigation, and the subsequent survival of bacteria on the adaxial surface of lettuce leaves. Two experiments were conducted in Salinas Valley, California: (1) to quantify the transfer of indicator E. coli from chicken and rabbit fecal deposits placed in furrows to surrounding lettuce heads on raised beds, and (2) to quantify the survival of inoculated E. coli on Romaine lettuce over 10 days. E. coli was recovered from 97% (174/180) of lettuce heads to a maximal distance of 162.56 cm (5.33 ft) from feces. Distance from sprinklers to feces, cumulative foliar irrigation, and lettuce being located downwind of the fecal deposit were positively associated, while distance from fecal deposit to lettuce was negatively associated with E. coli transference. E. coli exhibited decimal reduction times of 2.2 and 2.5 days when applied on the adaxial surface of leaves within a chicken or rabbit fecal slurry, respectively. Foliar irrigation can transfer E. coli from feces located in a furrow onto adjacent heads of lettuce, likely due to the kinetic energy of irrigation droplets impacting the fecal surface and/or impacting furrow water contaminated with feces, with the magnitude of E. coli enumerated per head of lettuce influenced by the distance between lettuce and the fecal deposit, cumulative application of foliar irrigation, wind aspect of lettuce relative to feces, and time since final irrigation. Extending the time period between foliar irrigation and harvest, along with a 152.4 cm (5 ft) no-harvest buffer zone when animal fecal material is present, may substantially reduce the level of bacterial contamination on harvested lettuce

Global irrigation water demand: Variability and uncertainties arising from agricultural and climate data sets

Agricultural water use accounts for around 70% of the total water that is withdrawn from surface water and groundwater. We use a new, gridded, global-scale water balance model to estimate interannual variability in global irrigation water demand arising from climate data sets and uncertainties arising from agricultural and climate data sets. We used contemporary maps of irrigation and crop distribution, and so do not account for variability or trends in irrigation area or cropping. We used two different global maps of irrigation and two different reconstructions of daily weather 1963–2002. Simulated global irrigation water demand varied by ∼30%, depending on irrigation map or weather data. The combined effect of irrigation map and weather data generated a global irrigation water use range of 2200 to 3800 km3 a−1. Weather driven variability in global irrigation was generally less than ±300 km3 a−1, globally (\u3c∼10%), but could be as large as ±70% at the national scale

MICROECONOMICS OF IRRIGATION WITH SALINE WATER

Water management and reuse at the field level are analyzed under saline, limited drainage conditions. A function relating crop yield and deep percolation flows to applied water and salinity concentration is developed. This function fits simulated data well and is tractable for theoretical and empirical analysis of irrigation economics. With a single irrigation source, irrigation water for cotton and tomatoes at first increases and the decreases with salt concentration. Drain-water reuse is found to be an efficient strategy in events of high surface-water prices and costly solutions to drainage-related environmental problems. However, blending freshwater and drainage appears plausible only under surface water scarcityResource /Energy Economics and Policy,

Effects of Irrigation and Tree Spacing on Soil and Air Temperature Profiles of Olive Orchards

Changes on the climate of the boundary layer occur when a vegetation cover above a bare soil is introduced, namely on temperatures and humidity profiles, above and under soil surface. Since air and soil temperatures affect crop growth and development and also soil moisture, they have been used as driving variables in numerous crop growth and development models as well as in those referred to soil mineralization, evaporation, transpiration, etc. The aim of this work was to evaluate (a) the soil thermal behavior in two olive orchards (Olea europaea sp. europaea), both grown on soils with little profile development (Regosol and Cambisol) and subject to drip irrigation but with different spacing between trees, and (b) the air thermal profile over olive rows. Experiments were performed from April to June 2012 in Southern Portugal. Soil and air temperatures were measured by thermocouples. The two orchards changed spatial distribution of soil surface temperature, soil temperature profiles and air temperature within the canopy, either on a daily or hourly basis. Olive tree spacing and irrigation affected both the soil thermal behavior and air thermal profiles. Tree spacing affected the horizontal gradients established along the interrows (intensity and rhythm). Irrigation reduced hourly and daily mean soil surface temperatures and daily thermal amplitudes of both profiles. Differences were also found on damping depths of the thermal wave estimated for the driest and the wettest profiles. Along the row, the effect of shading seems to overlap that of irrigation in a hourly basis

A low environmental impact system for fertirrigation of maize with cattle slurry

The applicability of an alternative system for managing and distributing cattle slurry during irrigation on maize was evaluated. An experiment was carried out by equipping a traveller boom with drop tubes and fed from a hose-reel machine. The new system was used for the distribution of the liquid separated fraction of slurry mixed with irrigation water (fertigation) on the soil surface between the rows of the crop. This system was compared with the conventional management system, utilizing a tank wagon equipped with splash plate for slurry application and a fixed irrigation system for irrigation. Analysis on leaching water samples indicate that the quality of percolation water is better due to a reduction in nitrate nitrogen losses. Besides, this alternative technique reduces the emissions of ammonia in the air and consequently the diffusion of ammonia in the atmosphere