Strategies to mitigate secondary salinization in the Indus Basin of Pakistan: a selective review

Salinity control / Water table / River basins / Irrigation management / Water quality / Irrigation practices / Drainage / Sodic soils / Pakistan

Mechanically reclaiming abandoned saline soils: a numerical evaluation

Water quality / Groundwater / Simulation models / Calibrations / Water table / Water balance / Hydraulics / Soil reclamation / Soil water / Flow / Soil properties / Salinity / Pakistan / Punjab / Sindh

Development of a Combined Quanity and Quality Model for Optimal Groundwater Management

Presented is a procedure for incorporating solute transport as linear constraints within computer models for optimizing regional groundwater extraction strategies. The MODCON modelling procedure uses linear goal programming, embedded linearized equations for flow and solute transport and a MOC simulation model. Assumed is 2D flow and solute transport and a dispersed conservative contaminant. The MODCON procedure develops steady groundwater extraction strategies that will satisfy future groundwater quality constraints while simultaneously causing future piezometric heads to be as close to current heads as possible. The procedure is applied to a 160 square mile area in southeastern Arkansas

Development of a combined quantity and quality model for optimal unsteady groundwater management

Presented is a procedure for incorporating solute transport as linear constraints within computer models for optimizing regional groundwater extraction strategies. The MODCON modelling procedure uses linear goal programming, embedded linearized equations for flow and solute transport and a MOC simulation model. Assumed is 20 flow and solute transport and a dispersed conservative contaminant. The MODCON procedure develops steady groundwater extraction strategies that will satisfy future groundwater quality constraints while simultaneously causing future piezometric heads to be as close to current heads as possible. The procedure is applied to a 160 square mile area in southeastern Arkansas

Development of linear water quality constraints for optimal groundwater management

Proposed is a procedure for incorporating solute transport as linear constraints within computer models for optimizing regional groundwater extraction strategies. . MODCON procedure uses linear goal programming. embedded linearized equations for flow and solute transport. and MOC simulation model. Assumed is 20 flow and solute transport. and a dispersed conservative contaminant

Irrigation application efficiency and uniformity of water distribution using multi-outlet pipe and resource conservation technologies

Irrigation experiments were conducted during November to April under wheat crop in the winter season of 2012-13 and 2013-14 in the farmer’s field at Galibkhedi village located in Karnal District, Haryana State, India. In the study, collapsible multi-outlet pipe (MOP) along with single outlets pipe (SOP) was tested in farmer’s field under wheat cultivation. Irrigation was carried out in five treatments including tillage (T) with SOP and MOP; zero-tillage (ZT) with SOP and MOP, and furrow irrigation with raised bed (FIRB). Iso-time profile of waterfront spreading and advance indicated that irrigation water distribution was uniform under the plot irrigated using MOP as compared to plot irrigated using SOP. In addition, water distribution was uniform under zero tilled plots as compared to tilled plot. Results implied that MOP has several advantages over SOP in terms of application efficiency (AE) and uniformity of water distribution. Average application efficiency for the first study year was found to be in the order of ZT-MOP (82.41%) > FIRB (76.79%) > ZT-SOP (75.25%) > T-MOP (74.85%) > T-SOP (69.79%). Average application efficiency for the second study year was found to be in the same order as first year with some deviation in values. In the second year values of mean application efficiencies were ZT-MOP (82.58%) > FIRB (77.13%) > ZT-SOP (73.04%) > T-MOP (69.65%) > T-SOP (66.13%). Overall, this study concludes that irrigation under wheat crop using collapsible multi-outlet pipe (MOP) with zero tillage practices is a suitable option for surface irrigation that accomplishes uniform distribution of water with higher application efficiency

SWAGMAN-Whatif, an interactive computer program to teach salinity relationships in irrigated agriculture

Managing salt-affected irrigated lands and marginally salinine irrigation water requires understanding the interactions among soil salinity, crop salt tolerances, soil physical properties, irrigation water quality, irrigation management, water table depth and quality, climate, and crop yield. An interactive computer program was developed to simulate interactions among the above factors. It shows how changing one factor impacts the others for a growing season. The user selects a climate, crop, and soil characteristics from menu lists, then sets the water table depth and quality, irrigation water quality, and develops an irrigation schedule. On execution, surface runoff, water table rise or fall, and the relative yield reductions due to overirrigation, underirrigation, and salinity are shown numerically for 1 yr. Soil water content, soil salinity, water table depth changes, and rain and irrigation events are also shown graphically. An IBM-compatible computer with a math coprocessor executes the program in 6 to 10 s. This is an educational tool designed to teach the concepts of salinity and irrigation management and is not an irrigation scheduling program nor a management tool. Two versions have been developed, one using metric units, southern hemisphere growing seasons, and Australian terminology; and a second using northern hemisphere growing seasons and U.S. units and terminology. The U.S. version also allows use of metric units. The program is supplied in executable code with a user guide, a soil salinity manual, and a salinity units conversion slide rule

Predicting salinization in a heavy clay soil subjected to a saline shallow water table

Salt increase in a heavy clay soil due to capillary rise was simulated by an analytical model and a numerical model. Predicted values were compared with experimental data. The analytical model was inadequate in predicting salinisation in a dynamic crop/soil system. When root growth was accounted for, the numerical model satisfactorily predicted salt increase in the soil profile

Models for estimating capillary rise in a heavy clay soil with a saline shallow water table

Shallow saline water tables underlie large areas of the clay soils in the Murray basin of Australia. Accurate estimation of capillary rise is important in formulating management strategies to avoid degradation of such soils. Measured capillary rise from a saline water table was compared with capillary rise estimated by three mathematical models of varying complexity and input requirement. A quasi steady state analytical model (QSSAM), a transient state analytical model (TSAM) and a numerical model (NM) were used. An undisturbed heavy clay soil core of 0.75 m diameter and 1.4 m deep was subjected to a static saline water table at 1.2 m from the surface. A wheat crop was grown on the core and the weekly capillary rise from the water table was measured. The electrical conductivity of a 1 : 2 soil : water extract was determined at 0.15 m depth intervals before and 21 weeks after the introduction of the saline water table. The QSSAM did not satisfactorily estimate the initial wetting of the subsoil and the estimated capillary rise was considerably lower than the measured values. Capillary rise estimated by the TSAM was reasonably close to the measured values, but the weekly rates fluctuated considerably. The NM estimated capillary rise quite satisfactorily throughout the experiment. Except near the soil surface, the electrical conductivity values estimated by the NM were close to the measured values. For estimating total capillary rise over large areas, the TSAM is preferred over the NM because of its fewer input requirements and shorter execution time