Managing salinity for sustainability of irrigation in areas with shallow saline ground water

Irrigation will be required to meet the demands of the world population for food. Water will also be needed to meet the municipal, industrial, and environmental demands of the growing population. As a result irrigation water supplies will be reduced and irrigators will probably be forced into using degraded water as part of the supply and the possibility for increased salinity in the soil profile will occur. Drainage will be required to assist in the management of the water needed for leaching to prevent soil salinisation. Drainage water containing salt and other contaminants creates a water quality problem for the water body receiving the drainage water. The paper presents the results of three cases studies that address the issue of disposal of saline drainage water through reuse for supplemental irrigation, water table control, and changing the design criteria for subsurface drainage as methods to reduce the drainage volume. The first study demonstrated that over 50% of the crop water requirement can be met with saline drainage water and that salinity in the soil profile can be managed to not adversely affect yields. This is not the case if the drainage water contains high levels of boron. The second study demonstrated that the water table can effectively be manipulated if the drainage system is properly installed. The third study showed the reduction in salt load as a result of implementing drainage control on deep drains or installing shallow drains. The results from these studies demonstrate that irrigated agriculture is sustainable in arid and semi-arid areas through improved management of the subsurface drainage system

Potential for up-scaling Nimr reed bed facilities, Oman : feasibility study

This report describes the findings of a feasibility study to treat oil contaminated water using reed beds, and consume the treated saline water using forestry. The feasibility study focused on the social, technical and economical feasibility of a project designed to process 45,000 m3 of water per day. Possible effects of a large scale operation on interactions between Petroleum Development Oman and local population are listed, and suggestions on the social processes involved are made. The economics of reed bed water treatment and water consumption through the use of forestry are determined and compared with the current practise of deep well disposal. The economics of the treatment-forestry system are more favorable than the economics of the deep well disposal. The technical analysis shows that the reed beds are able to treat water to remove hydrocarbons, and suggestions for management, design and development of the system are given

Systeemverkenning Quarles van Ufford

In 2004 is een systeemverkenning van het bemalingsgebied Quarles van Ufford gemaakt op basis van vooral literatuurstudie. Het gebied is gelegen in het westelijk deel van het Land van Maas en Waal en is ca 12.000 ha groot. Voor dit kleigebied is de nutriëntenbelasting bekeken, in relatie tot kwel, grondgebruik, wateraanvoer en waterafvoe

Capacity Building in IWRM: The IWRM MSc Curriculum at the Water and Environment Centre, Republic of Yemen

Integrated Water Resources Management (IWRM) is an interdisciplinary approach to water resources management, as opposed to water resources development. In developing an MSc curriculum at the Water and Environment Centre (WEC) at Sana'a University in the republic of Yemen, three goals were defined. The first goal is to integrate the knowledge and skills developed at the different faculties at Sana'a University into an integrated teaching curriculum. The second goal is to meet the demands from the Yemeni water sector, such that graduates have the skills and knowledge required for their future jobs. The third goal is to make the IWRM curriculum institutionally and financially sustainable, such that it can continue to be part of the Sana'a University MSc Program. The development of the IWRM MSc curriculum is done in a participative way, using support of other international universities, to ensure that the complete 2-year program of the curriculum is a coherent package, and not a collection of individual classes. The first semester is designed to develop the same level of knowledge for the inflow students, who will likely have a variable background. The second semester is designed to teach integration of knowledge and skills on the topic of water management. The third and fourth semester are designed to improve research skills and finish the MSc with thesis work. The program will start at the end of 2005, but the process of development of the curriculum has already developed a common sense of integration in Water Resources Management with lecturers from multiple disciplines

Calibration of capacitance probe sensors in a saline silty clay soil

Capacitance probe sensors are a popular electromagnetic method of measuring soil water content. However, there is concern about the influence of soil salinity on the sensor readings. In this study capacitance sensors are calibrated for a saline silty clay soil. An electric circuit model is used to relate the sensor's resonant frequency F to the permittivity () of the soil. The circuit model is able to account for the effect of dielectric losses on the resonant frequency. Dielectric mixing models and empirical models are used to relate the permittivity to the soil water content (). The results show that the electric circuit model does not fit the F¿() data if the calibrated bulk electrical conductivity (EC) model is used. The dielectric losses are overestimated. Increasing the exponent c in the tortuosity factor of the bulk EC model and thereby lowering the bulk EC and the dielectric losses improves the performance of the model. Measured and calculated volumetric water contents compare reasonably well (R2 = 0.884). However, only 73 out of 88 data points can be described. The rejected points are invariably at high water contents where the high dielectric losses result in the sensor frequency being insensitive to ()

Irrigation management to optimize controlled drainage in a semi-arid area

On the west side of the San Joaquin Valley, California, groundwater tables have risen after several decades of irrigation. A regional semi-permeable layer at 100 m depth (Corcoran Clay) combined with over-irrigation and leaching is the major cause of the groundwater rise. Subsurface drain systems were installed from the 60¿s to the 80¿s to remove excess water and maintain an aerated root zone. However, drainage water resulting from these subsurface systems contained trace elements like selenium, which were determined at toxic levels to fish and waterfowl. To maintain healthy levels of salt and selenium in the San Joaquin River, the natural drain out of the San Joaquin Valley, outflow of drainage water from farms was severely restricted or completely eliminated. Several on-farm management methods are being investigated to maintain agricultural production without off-farm drainage. One method is drainage water reuse through blending with irrigation water. Another method is to reuse drainage water consecutively, where drainage water from one field is used as irrigation water for another field. Progressively more salt tolerant crops need to be grown in such a system along the reuse path, and salts can eventually be harvested using solar evaporators. A method described in this paper aims to reduce the volume of drainage water during the growing season by increasing shallow groundwater use by crops before it is drained from the field. Five years of crops were grown on two weighing lysimeters using drip irrigation. Two years of cotton were grown under high frequency drip irrigation (applications up to 10 times a day), followed by two years of safflower (early season crop) and one year of alfalfa (perennial) under low frequency drip irrigation (twice a week). One lysimeter maintained a shallow groundwater table at 1.0-m below soil surface, while the other lysimeter was freely drained at the bottom (3.0-m below soil surface). High frequency irrigation requires more irrigation water over a season than low frequency irrigation in the presence of shallow groundwater, since low frequency irrigation induces more shallow groundwater use by crops. Groundwater use for cotton was measured as 8% of total seasonal crop water use, while measurements under safflower showed that 25% of seasonal crop water use came from groundwater. Measurements under alfalfa, in its first year of establishment, showed 15% of seasonal crop water use coming from the groundwater. To maintain a sustainable system, leaching of salts need to occur. Leaching under the proposed irrigation/drainage management system would occur in the early growing season with winter precipitation, pre-plant irrigation and the first irrigation of the growing season, when the water table can be maintained at shallower depths through restriction of the outflow of the subsurface drainage system (groundwater control)

Irrigation management to optimize controlled drainage in a semi-arid area

On the west side of the San Joaquin Valley, California, groundwater tables have risen after several decades of irrigation. A regional semi-permeable layer at 100 m depth (Corcoran Clay) combined with over-irrigation and leaching is the major cause of the groundwater rise. Subsurface drain systems were installed from the 60¿s to the 80¿s to remove excess water and maintain an aerated root zone. However, drainage water resulting from these subsurface systems contained trace elements like selenium, which were determined at toxic levels to fish and waterfowl. To maintain healthy levels of salt and selenium in the San Joaquin River, the natural drain out of the San Joaquin Valley, outflow of drainage water from farms was severely restricted or completely eliminated. Several on-farm management methods are being investigated to maintain agricultural production without off-farm drainage. One method is drainage water reuse through blending with irrigation water. Another method is to reuse drainage water consecutively, where drainage water from one field is used as irrigation water for another field. Progressively more salt tolerant crops need to be grown in such a system along the reuse path, and salts can eventually be harvested using solar evaporators. A method described in this paper aims to reduce the volume of drainage water during the growing season by increasing shallow groundwater use by crops before it is drained from the field. Five years of crops were grown on two weighing lysimeters using drip irrigation. Two years of cotton were grown under high frequency drip irrigation (applications up to 10 times a day), followed by two years of safflower (early season crop) and one year of alfalfa (perennial) under low frequency drip irrigation (twice a week). One lysimeter maintained a shallow groundwater table at 1.0-m below soil surface, while the other lysimeter was freely drained at the bottom (3.0-m below soil surface). High frequency irrigation requires more irrigation water over a season than low frequency irrigation in the presence of shallow groundwater, since low frequency irrigation induces more shallow groundwater use by crops. Groundwater use for cotton was measured as 8% of total seasonal crop water use, while measurements under safflower showed that 25% of seasonal crop water use came from groundwater. Measurements under alfalfa, in its first year of establishment, showed 15% of seasonal crop water use coming from the groundwater. To maintain a sustainable system, leaching of salts need to occur. Leaching under the proposed irrigation/drainage management system would occur in the early growing season with winter precipitation, pre-plant irrigation and the first irrigation of the growing season, when the water table can be maintained at shallower depths through restriction of the outflow of the subsurface drainage system (groundwater control)

Systeemverkenning Quarles van Ufford

In 2004 is een systeemverkenning van het bemalingsgebied Quarles van Ufford gemaakt op basis van vooral literatuurstudie. Het gebied is gelegen in het westelijk deel van het Land van Maas en Waal en is ca 12.000 ha groot. Voor dit kleigebied is de nutriëntenbelasting bekeken, in relatie tot kwel, grondgebruik, wateraanvoer en waterafvoe