bewater consumption must be measured on irrigation time and pipe capacity. Meters are used for systems under pressure. In Jordan, Al Hadidi (2002) describes the widespread installation of meters at private wells; billing can discourage overexploitation of the aquifers. Weak cost recovery translates into financial resources inadequate to maintain minimum operations and maintenance, causing services to deteriorate (Baroudy et al., 2005).

Most CWANA countries have adopted water pricing for irrigation and drainage. Water tariffs are increasingly important to manage demand. In Morocco and Tunisia water bills cover operating costs but exclude infrastructure costs. Water pricing is moving from reimbursement of maintenance costs to protecting the natural resource. However, some disadvantaged areas still benefit from government support. Generally, governments continue to support investment and fill the gap left by payment arrears (Baroudy et al., 2005).

2.1.3.4 Effect of global changes on water resources

Climate change will affect precipitation, evapotranspiration, runoff-and ultimately, water resources. Changes in the water cycle likely will affect the magnitude, frequency and cost of extreme weather and the water available to meet growing demand. Recent reports (IPCC, 2007) show that climate change is likely to increase the days of intense precipitation and the frequency of floods in northern latitudes and snowmelt basins. Severe droughts could also increase because of a decrease in rainfall, more frequent dry spells and greater evapotranspiration. In the arid and semiarid areas of CWANA modest changes in precipitation can have a large effect on water supply. In mountain watersheds, higher temperatures will increase the ratio of rain to snow, accelerate the spring snowmelt and shorten the snowfall season, leading to a faster, earlier and greater spring runoff.

Temperature projections of climate are less speculative than projections of precipitation. The scenario problem lies in the scale mismatch between global climate models, with monthly data over several tens of thousands of square kilometers and catchment hydrological models, which require daily data and at a resolution of a few square kilometers. In CWANA few studies on climatic change scenarios are available, CWANA is not in the GEWEX experiment (Global Energy and Water Experiment) while the HYMEX (Hydrological Cycle in Mediterranean Experiment) will cover part of CWANA.

2.1.4 Water management infrastructure for agriculture

The control of water always has been critically important in the development of civilizations (Job, 1992). Since ancient times, different hydraulic systems have been built to augment rain and collect, store and transport water (El Amami, 1983; Khouri et al., 1995; Prinz, 1996). From simple cisterns in the ground, vital for the survival of families in arid zones, to large dams that are part of national policies to guarantee water to the greatest possible number of people, water storage always has been a primary preoccupation of CWANA governments, which face recurring droughts and limited water (Hamdi and Lacirignola, 1994; Jaber, 1997; ESCWA, 1998a).

The earliest recorded dam was on the Nile River at

Kosheish, where a masonry structure 15 m high was built about 2900 BCE to supply water to King Menes' capital at Memphis. Evidence exists of a masonry-faced earthen dam built about 2700 BCE at Sadd-el-Kafara, about 30 km south of Cairo; this dam failed shortly after completion when, in the absence of a spillway, it was overtopped by a flood. The oldest dam in use is a rock-fill structure about 6 m high, built around 1300 BCE, on the Orontes River in Syria. By 1950, governments were building more dams as populations increased and national economies grew. Today nearly half of the world's rivers have at least one large dam. However, the last 50 years have also highlighted the performance and the social and environmental effects of large dams. Dams have fragmented and transformed the world's rivers and perhaps 40-80 million people have been displaced by reservoirs.

2.1.4.1 Large dams

Since the 1950s, CWANA has built many dams and some are among the largest in the world. In November 2000, the World Commission on Dams published an overview of dams and development (Clarke, 2000). It is based on 150 case studies, 13 in CWANA: Iran, Morocco, Pakistan, Tunisia and Turkey. While the large dams vary greatly in performance, most dams in CWANA underperform in achieving the intended benefits and services. In some instances, though, benefits occurred for much longer than predicted and still continue. Adverse effects on ecosystems occur frequently and many were unanticipated.

Irrigation components fell well short of targets in the irrigation command area developed, irrigated area achieved and, to a lesser extent, cropping intensity. It is difficult to find data on predicted and actual crop values. A high variability is observed among projects, data on smaller dams suggested greater consistency in performing closer to targets than larger ones. In contrast to irrigation, hydropower performance of large dams was, on average, closer to the goal, although performance varied.

Larger than necessary reservoirs may reflect overestimates of water demand or high reserves for drought. Multipurpose projects had higher variability and lower average performance than single-purpose projects. When a new dam is planned, the number of families and people that will be displaced and involuntarily resettled is routinely underestimated. The lack of records reporting these aspects also remains contested and continues to fuel controversy in the large-dam debate. Many positive and negative ecosystem effects from large dams were unanticipated, even in the 1990s. Mitigation was the most practiced response to ecosystem effects, but it has mostly failed or worked only sporadically.

Participation and transparency in decision making were neither open nor inclusive through to the 1980s. Emphasis has grown on transparency and participation in decision making involving large dams, especially in the 1990s. Many dam projects still do not plan for public participation of affected people. Participation of NGOs has increased in the projects since the 1990s.

2.1.4.2 Small dams

CWANA countries have had, over varying lengths of time, policies of constructing small dams designed to use surface water and control erosion. The dikes of these dams are be-