Rehabilitation of Irrigation Distribution Systems: The Case of Jericho City
Efficiency enhancement in irrigation distribution system (IDS) contributes to substantial water savings. This paper aims to present the methodology and lessons learned from efforts to improve efficiency in the irrigation distribution system of Jericho City. This effort presents a new paradigm in water management in water scarce countries, which focuses on both supply and demand management rather than on supply augmentation. Converting the existing irrigation canal system to a pressurized pipe network carries out rehabilitation of IDS in Jericho City. Analysis of the new IDS is performed through computer simulation. Considerations and constraints for sustainable irrigation management are presented.
Improving water use in agriculture : experiences in the Middle East and North Africa
Emerging water shortages are of great concern in many countries of the region. As the agricultural sector is generally by far the most important water consumer and higher priority is given to meeting domestic and industrial water demands, it is to be expected that gradually less water will be available for agriculture. An overview is given of present system and on-farm water use efficiencies and the potential for water savings and yield increases through the use of improved distribution networks and more appropriate irrigation technologies for smallholders. The water conservation efforts of Israel, Cyprus and Jordan are examined in detail with respect to institutions, the irrigation infrastructure, water charges and demand management, operation and maintenance, irrigation scheduling and extension, technology development and transfer, the role of the private sector, quality control on irrigation equipment, land tenure and land consolidation, and water users associations. The World Bank's experience with lending for the irrigation sector in the region is also described. The elements that would need to be considered for inclusion in a national program for water conservation in the agricultural sector are identified.
Pesticide contamination of groundwater in western Europe
In recent years, many measurements have been made of residues of pesticides in shallow and deep groundwater in western Europe. Some triazine herbicides and their transformation products have been detected most frequently. The average concentration in measuring series for deep groundwater was usually below 0.1 μg l−1, and the highest values were usually below 0.5 μg l−1. The concentrations of mecoprop in deep groundwater ranged up to 0.6 μg l−1 and those of bentazone to almost 1.0 μg l−1. Some other herbicides were found at comparatively high concentrations and the highest values were found for TBA and TCA in tile-drain water. The soil fumigant 1,3-dichloropropene was mainly found in shallow groundwater, but its admixture 1,2-dichloropropane was also found in deep groundwater (range up to 10 μg l−1, sometimes even higher). Residues of the nematicides aldicarb and oxamyl have been measured in shallow and intermediate groundwater, but measurements for deep groundwater are still lacking. Some carbamoyl-oximes were incubated in subsoil materials to study their transformation and their rate of transformation in anaerobic subsoils was surprisingly high. The maximum admissible concentration of 0.1 μg l−1 in a Directive of the European Communities of 1980 is the subject of much debate, because a toxicological basis is lacking.