No abstract

Many agricultural production areas worldwide are characterized by high variability of water supply conditions, or simply lack of water, creating a dependence on irrigation since Neolithic times. The aim of this paper is to provide an overview of the evolution of irrigation of agricultural lands worldwide, based on bibliographical research focusing on ancient water management techniques and ingenious irrigation practices and their associated land management practices. In ancient Egypt, regular flooding by the Nile River meant that early agriculture probably consisted of planting seeds in soils that had been recently covered and fertilized with floodwater and silt deposits. On the other hand, in arid and semi-arid regions farmers made use of perennial springs and seasonal runoff under circumstances altogether different from the river civilizations of Mesopotamia, Egypt, India, and early dynasties in China. We review irrigation practices in all major irrigation regions through the centuries. Emphasis is given to the Bronze Age civilizations (Minoans, Egyptians, and Indus valley), pre-Columbian, civilizations from the historic times (e.g., Chinese, Hellenic, and Roman), late-Columbians (e.g., Aztecs and Incas) and Byzantines, as well as to Ottomans and Arabs. The implications and impacts of irrigation techniques on modern management of water resources, as well as on irrigated agriculture, are also considered and discussed. Finally, some current major agricultural water management challenges are outlined, concluding that ancient practices could be adapted to cope with present challenges in irrigated agriculture for increasing productivity and sustainability.

Wastewater in most countries of the Near East Region (NER) is being more and more recognized as of vital importance to be treated and made safe for reuse. It contributes considerably to the water budget in several countries, particularly those suffering from water scarcity. Treated wastewater is used directly in irrigation of farms or landscape green areas. Limited indirect use includes recharge of groundwater aquifers to control over-draft and salt intrusion in coastal areas. A large share of wastewater is still not treated and part of it is used in an uncontrolled manner, including for the production of uncooked food crops the consumption of which poses health risks. Expansion of treated wastewater reuse in the region is linked to a number of issues and constraints. The high cost of treatment and management of reclaimed wastewater is one of the major limitations facing the week economy of most countries. Unclear polices, institutional conflicts and lack of regulatory frameworks constitute other important constraints that hinder implementation and proper operation of wastewater reuse projects. The manpower capacity is at varying levels between countries, but additional training and capacity strengthening are generally needed throughout the region. This paper gives an overview of the existing practices of wastewater reuse in the NER and of the constraints facing it. It concludes with recommendations and policy options that are likely to lift these constraints and to make a better use of the wastewater potential.

The Near East region extends from Turkey in the north to Somalia in the south and from Mauritania in the west to Afghanistan in the east. It is characterized by aridity and scarcity of water which explains its dependence on irrigation since ancestral times. The aim of this paper is to give a brief overview of the history of water management and irrigation developments in the region, based on remnants and bibliographical research, with a focus on ancient water management techniques and ingenious irrigated agriculture practices, including the use of non conventional water resources. The implications and impacts of these techniques on modern management of water resources and irrigated agriculture are also discussed.

The effect of soil bulk density on soil water diffusivity and on infiltration is studied using data from 13 soils, widely ranging in texture. It is shown for horizontal infiltration of water into initially air dry soil that although changes in the slopes of plots of the distance to the wetting front as a function of square root of infiltration time corresponding to different bulk density values actually depend on soil type, they may be considered independent. Hence a generalized exponential equation is developed which expresses the soil water diffusivity of any soil as a function of soil water content and soil bulk density, knowing only the rate at which the wetting front advances for only one value of the bulk density.