Impact of global climate change on water resources in the Israeli, Jordanian and Palestinian region

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Book Chapter

Reference

Impact of global climate change on water resources in the Israeli, Jordanian and Palestinian region

SALIM, Nidal, WILDI, Walter

Abstract

Water resources in the West Bank region, as well as in Israel and Jordania depend directly from precipitations. Short and long term climatic variations are responsible for drought situations and periods of water shortage. In this perspective, the current climate change is a challenge for the governamental offices and the populations.

SALIM, Nidal, WILDI, Walter. Impact of global climate change on water resources in the Israeli, Jordanian and Palestinian region. In: NEAR curriculum in natural environmental science. 2005.

Available at:

http://archive-ouverte.unige.ch/unige:90828

Disclaimer: layout of this document may differ from the published version.

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Nidal Salim* and Walter Wildi

Institute F.-A. Forel, Section of Earth Sciences, University of Geneva, Switzerland, *nidal.salim@terre.unige.ch

This case study can be used in conjunction withModule V Global Issues, Section 2 Impact of global climate change on water resources of the NEAR curriculum. It demonstrates how climatic and hydrological information can be used to demonstrate the impact of climate change on the water resources of a geographically diverse area that is already experiencing water stress.

1 Introduction

Research on climate variability and change is being focused on climate elements that are particularly important to human and natural systems especially temperature, precipitation, clouds, winds and storminess. These and other factors are likely to be affected by changes in the Earth system that results from natural events as well as by human activities. Changes in climate variability, especially in conjunction with the development of social and ecological systems, are likely to be of greatest significance because such changes could affect vital life-sustaining ser- vices that humans draw from the environment. Climate change has impacts on water resources, and subsequently, on the sustainability of our environment. Climate change due to increased atmospheric CO₂and other trace gases may affect the water supply for municipal, industrial and agriculture uses (Changet al., 1992; Lettenmaier and Sheer, 1991; Waggoner, 1990). Climate change will affect the water balance, and particularly the amount of runoff and recharge, which in turn determines the water resources available for human and ecosystem uses.

Evidence of global climate change is increasingly being recognized together with the fact that it may result in more frequent floods and droughts. At present, the Middle East is char- acterized as a water-stressed area and is suffering increasingly from water shortage and environmental pollution. The problem of scarcity is further compounded by the fact that precipitation is low and highly variable. In the last few years the rainfall was less than expected and followed an alarming trend downwards resulting in acute water shortage. Consequently, since January 1997

NEAR Curriculum in Natural Environmental Science, 2005,Terre et Environnement, Vol. 50, 125–140, ISBN 2–940153–49–3

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restrictions in supply to both agriculture and domestic sectors were put into effect. Emergency water resources management and drought mitigation measures were introduced. Water scarcity in the region becomes more acute when demand and supply is considered in the context of future socioeconomic and ecological changes that may occur. The socioeconomic factor with the greatest potential impact is population growth; the ecological factor of greatest concern is global climatic change. The supply of water is limited to that naturally renewed by the hydrologic cycle or artificially replenished by anthropogenic activities. Periodically, the amount of natural replenishment can exceed water demands during unusually wet periods or fall far below demand during drought periods. The reality of the growing needs for a limited resource is one of the factors driving water conservation efforts and consideration of alternative water resources.

2 Description of the study area

This case study presents an overview of the water resources in areas of the Israeli, Jordanian and Palestinian territories in the Western part of the Middle East and a part of the eastern shore of the Mediterranean. Arial and site specific (hydrologic, meteorological, and geological) data have been gathered to enable a broad assessment of the adaptation and vulnerability of the overall water conditions. This area consists of coastal plain (a flat topography with a white-sand shore- line), mountains formed of sedimentary rocks and deserts (Fig. 1, Slide 4).

3 Data compilation

Data have been collected by different agencies within the region in different time periods and are heterogeneous. The available data have been compiled by the U.S. Geological Survey. All the data used in the water resources trend analyses were retrieved from these databases which are separately maintained by the Israeli Hydrological Service (IHS), the Jordanian Ministry of Water and Irrigation (MWI), and the Palestinian Water Authority (PWA) offices. Data selected for trend analyses in this study were: groundwater level, spring discharge, and stream flow. All periods were selected to include 1998, which was the last year for which complete data was available. The shortest period analyzed was 1984–98 and the longest was 1974–1998.

4 Hydrological cycle

Water resources and climate are closely related to each other. This relationship can be presented as a water cycle, with water movement from the oceans (or any open water), to the atmosphere and to the Earth, returning to the atmosphere through various stages or processes such as precipitation, interception, runoff, infiltration, percolation, storage, evaporation, and transportation.

This shows the relationship between water resources and climatic parameters (Slide 5). The main climatic parameters taken in consideration in this study were limited to precipitation,

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temperature, evapotranspiration and its relation with groundwater fluctuation, which together provide information on water availability, which in turn influences directly water supply.

5 Climate and variations in climate

The climate ranges from almost subtropical to arid/semi-arid with strong variation throughout the year; i.e. typical Mediterranean cycle of hot, dry summers and mild, rainy winters. Changes in rainfall occur over short distances, varying from less than 50 mm per year in the Eastern and Southern deserts to about 900 mm per year in the southern part of the region as shown in Fig. 2 (Slide 6). Rainfall occurs in desert areas mainly during thunderstorms – between October and May. Over 80 per cent of the annual rainfall occurs during the period of December to March (WAJ, 1989). Average rainfall decreases from west to east and from north to south. Bakour and Kolars (1994) indicate that the entire region (sometimes called the Mashrek) is a transition zone.

They emphasize that the dominant hydrological characteristic is the combination of aridity and uncertainty.

Figure 1 Physical geography of the study area. After EXACT, 1999.

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Large rainfall variations also occur from year to year. Consecutive years of relatively high or low annual rainfall have an enormous effect on the region and, in the case of dry years, present the greatest challenge to the management of the region’s precious water resources. These consecutive-year patterns also may affect water-use practices, policies, and expectations with the region lurching from successive years of drought or near drought conditions to years of rains heavy enough to cause flooding and loss of life. Therefore, it is much more important to have a good understanding of the spatial, seasonal, and annual variations in rainfall than of annual na- tional averages.

Temperature also varies across the area, generally according to latitude and altitude and by physiographic province. The hilly areas of the Mountain Belt and Jordan Highland and Pla- teau experience cold winters and hot summers. In Amman and Jerusalem, average daily mean temperatures for January range from about 7 to 9 °C, whereas in summer the average mean temperature is about 24 °C. Average daily mean temperatures in the Jordan Rift Valley area range from about 15 °C in the winter, to about 31 °C in the summer. In the Coastal Plain, average daily temperatures are between 16 and 22 °C in the winter and between 20 and 31 °C in the summer.

The desert region has a continental climate with a wide range of temperatures. In August average

Figure 2 Rainfall in the study area. After EXACT, 1999.

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daily maximum temperatures are between 34 and 38 °C. In winter, the air is very cold and dry with an average daily minimum temperature between 2 and 9 °C. When cold air of polar origin penetrates the region, temperatures decrease to below freezing point. The region periodically experiences very hot days particularly during the summer months and this magnifies the effect on agriculture due to the north-to-south variation in rainfall, when winds called Sharav or Khamasini may produce temperature rises from 10 to 20 °C above normal and increase evapotranspiration. The Middle East experiences extreme seasonal variations in climate.

Figure 3 (Slide 7) divides the area into three main regions, the deserts, the mountain highlands and the coastal area and shows their variation in the precipitation, evaporation and temperature.

The desert area has the lowest precipitation and highest evaporation and temperature rate, while the coastal area enjoys the highest amount of precipitation and lowest temperature and evaporation. The mountain area tends to be moderate.

6 Water resources

Groundwater is the main source of water in the region (Slide 8). Groundwater basins are determined by structural features, intervening layers, or aquifer extent. The boundaries may change with time due to such factors as groundwater division, which may occur in response to pumpage or recharge. This is different from boundaries designated solely for administrative or operative reasons. The natural boundaries of one aquifer will not coincide with those of other aquifers of different ages occurring at different depths. Twenty basins can be distinguished in the area.

Surface water is a very limited resource because of generally low rainfall and high evapotranspiration. However, the main surface water features are the Jordan River and Lake

Coastal area Mountain area Desert

Figure 3 Variation in average monthly rainfall, temperature and evaporation for three sites representative of the three main geographical regions of the study area. After EXACT, 1999.

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Tiberias, the Dead Sea and Mediterranean Sea, in addition to other local wadis and rivers.

Annual streamflow generally declines from west to east with distance away from the Mediterra- nean moisture sources, and from north to south with increasing temperature and evaporation.

Streamflow typically is higher on the western side of the Mountain Belt, due to temperature and orographically induced precipitation, and decreases on the eastern side of the Mountain Belt descending into the Jordan Rift Valley.

7 Observed trend in climate change in the region

7.1 Temperature

Priceet al. (1999) observed an approximate 1 °C per 100 years rise in annual mean temperature in Cyprus and a relatively moderate increase in air temperature has been measured in cities of the Mediterranean basin, primarily in winter and less in the autumn and spring. However, most of the increase was measured in cities undergoing urbanization (Kutiel and Maheras, 1998;

Maheras and Kutiel, 1999). A spatial analysis of temperature changes in Israel during the last 40 years showed warming mainly in the centre and north (Ben-Gai et al., 1998a, 1999), with a cooling trend in the south and around Hadera (the site of a major power station). Thus, there ap- pears to be a general warming trend, with local exceptions related to anthropogenic factors (Ben Gaiet al., 1999). Figure 4 (Slide 9) shows trends in temperature in the Middle East since 1900 (IPCC, 2004).

7.2 Precipitation

Alpertet al. (2000) suggested an overall trend of decreasing precipitation over recent decades.

The decline in precipitation may be explained by a decrease in the frequency of mid-latitude cyclones in the East-Mediterranean (Druyan and Rind, 1993; Ben-Gaiet al., 1993). Some authors ascribe the changes in precipitation primarily to intra-seasonal changes in rain distribution.

Pazet al. (1998b, 2000) found that rainfall decreased in winter at most of the 15 stations studied around the Mediterranean (mainly in the eastern Mediterranean) but increased slightly in spring and summer, with no significant change in total rainfall during the period 1970–1990. Sharon (1993), on the other hand, found that changes in annual rainfall varied distinctly between regions in Israel, with only the coastal region showing a constant decline. This suggests that specific regional factors might play an important role in the local climatic trend. Rainfall measurements at different stations in the Mediterranean basin show similar declines in most regions of the basin (Paz et al., 1998a). High correlation between changes in vegetation and changes in sea level during the last 10,000 years in the Middle East suggests that the trend of decreasing precipitation in the Middle East may be attributed to global warming (Issar, 1995).

Several authors (Ottermanet al., 1990; Ben Gaiet al., 1993; Sharon, 1993; Sharon and Angert, 1998) have demonstrated an increase, rather than a decrease in overall precipitation in

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Israel’s southern coastline and the northern Negev, resulting from land-use changes: i.e. affores- tation, intensive agriculture under irrigation, and grazing restrictions. However, the pattern of precipitation has changed during the last 20 years as described below.

7.2.1 Shortened rainy season

Kutiel (2000), analyzing changes in the yearly distribution of rains in Israel from 1976 to 2000, found that the winter rainy season shortened over this period, particularly in the last decade. The length of period during which the cumulative amount of rainfall reached 20% and 50% of the annual rainfall was extended by 6 days and 4 days per decade, respectively, due to lower rainfall in October and November. This observation contrasts with former reports of increased rains in October (Steinberger and Gazit-Yaari, 1996). A delay in winter rains, with no extension of the rainy period may explain the decrease in Israel’s total annual rainfall.

7.2.2 Increased frequency of extreme weather events

The temporal and spatial distribution of rains in the Mediterranean basin is highly changeable, with rainfall varying greatly both from year to year and within the year (Kutiel, 2000). Even greater variability due to climate change is likely to be as important as, or more important than, changes in mean climate conditions for determining climate change impacts and vulnerability (IPCC, 1996). Analysis of spatial and temporal long-term trends in climate in Israel showed increased seasonal variability due to a decrease in the maximum and minimum temperatures (Tmax and Tmin, respectively) in the cool season, and an increase in Tmin and Tmax in the warm season (Ben-Gaiet al., 1999). These two opposite tendencies, observed at 40 stations over 31 years (1964–1994), may explain the absence of change in mean temperature. However, analysis of the same data did show increased temperatures in the centre and in the north. Ben Gai

Figure 4 Trends in temperature in the Middle East/Arid Asia region since 1990. After IPCC Special Report on The Regional Impacts of Climate Change And Assessment of Vulnerability.

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et al. (1998a, 1999), studying the frequency pattern of Tmin and Tmax from 1964 to 1994, divided the years into two sub-periods, 1964 to1979 and 1980 to1994, and compared the two periods. They found increased seasonal variability as well as increased frequency of extreme temperature events, demonstrated by the upper and lower tail of the temperature distributions.

7.2.3 Rainfall intensity

Alpertet al. (2000) showed that high-intensity rains increased in frequency, with fewer rains of moderate and weak intensity. Interestingly, former analyses of rain intensity have failed to show this trend (Dayan and Koch, 1999 and references therein). The analysis of Alpertet al. (2000) supports a prevailing notion of an increased incidence of extreme weather, particularly in the last decade.

7.3 Evapotranspiration

Rather than the expected increase in evapotranspiration rate (Segal et al., 1994), a trend of decreasing evapotranspiration was measured in the eastern Mediterranean (Paz et al., 2000), probably due to the observed lowering of SST (Sea Surface Temperature). However, with the anticipated increase in overall temperature, and probable increase in SST, the increase of 1.5 °C in the Mediterranean basin anticipated in Israel around 2100, is expected to increase evapotranspiration rates by 10% (Jeftic, 1993).

The Middle East climate has varied considerably over the past 10,000 years, with changes in precipitation ranging from 15 per cent to 40 per cent of the current average rainfall in southern Israel (Issar, 1995, 1996). The historical high correlation between human settlement and climate change in the Middle East (Issar, 1995) attests to the sensitivity of systems to climate change. Yet, available knowledge does not suffice for distinguishing between sensitivity and adaptability of each of the systems to climate change.

8 Trends in water resources

Time-series graphs were plotted to illustrate trends at individual sites. A comparison of water level trend for two periods (1982–1991 and 1992–1998), showed a negative trend, i.e. a decrease in water level for the two periods. This took into account the influence of the wet year 1991–1992 which was recorded as the wettest year in the area for over a century, with annual mean precipitation above 200 per cent in most areas. The analyses of water level show negative trends in both surface and groundwater:

1) Surface water level in the Dead Sea shows a negative trend over the last 100 years as shown in Fig. 5 (Slide 11). Lake Tiberias also shows a negative trend, while the Mediter- ranean Sea shows an increase in water level resulting from the influence of glacial melt.

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2) Groundwater level shows a negative trend in all basins except the coastal aquifer which is re- charged by treated wastewater and other sources such as water transported from the north.

Figures 6 and 7 (Slides 12 and 13) show the trends in a mountainous and a desert area.

9 Potential impacts of climate change (Slides 14 and 15)

Historical records illustrate the inter-relationship between human settlement and climate change. However, with available knowledge it is difficult to distinguish between sensitivity of climate to human activity and the adaptability of humans to climate change. Adaptation is the adjustment of an organism or population to a new or altered environment. Adaptation can also arise from decisions people make to adjust to the change. Exposure to climatic parameters is the stimulus to systems to adapt. The adaptability of a society’s systems to exposure depends on their sensitivity, i.e. the degree to which they are affected by their exposure (this is determined by the system’s own properties). Exposure, sensitivity and adaptability combine to determine the vulnerability of a system, that is the degree to which it is susceptible to adverse effects of climate change. Thus, the impact on a system depends on its vulnerability. The regional impacts of climate change can be categorized as desertification, hydrological impacts, recharge and water availability, and salt water intrusion.

9.1 Desertification

Increasing temperature and evaporation leads to a real decrease in soil moisture throughout the region which may lead to increased areas of desertification. Little change in vegetation is expected in arid (or desert) regions but the impact may be considerable in the semi-arid lands.

9.2 Hydrology

Water shortage is already a complex problem that is increasing sharply in many countries of the arid regions and which will continue to increase with climate change. Arid regions could experience large decreases in runoff of up to 40 per cent or 70 per cent in some areas as presented in

Metresbelowsealevel

415 410 405 400 395 390 385

Figure 5 Changes in surface water level in the Dead Sea. After EXACT, 1999.

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Figure 6 Trends in groundwater level in the mountain area, 1982–1998. After EXACT, 2000.

Figure 7 Trends in groundwater level in the desert area, 1982–1998. After EXACT, 2000.

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some analyses for some basins. Changes in land use and vegetation significantly reduce the permeability of the underlying soil, increasing the frequencies and intensities of surface run-off events, causing topsoil erosion and loss of water, resulting in further loss of vegetation, and hence higher frequency and intensity of run-off events. Thus, climate-change induced increased surface run-off will exacerbate desertification, increase flash floods, and increase water loss to the seas. Increased run-off, when coupled with sea level rise, will leads to the formation of swamps in the coastal areas.

9.3 Recharge and water availability

Changes in land use and vegetation significantly reduce the permeability of the underlying soil.

Reduced infiltration rates caused by increased surface runoff will also reduce aquifer recharge and water availability. This becomes obvious in all basins which suffer from a serious decline in water level, especially the mountain aquifers which are considered to be the most vulnerable areas. The Dead Sea is an example of surface water suffering sharply from water level decline.

The water level monitored continuously since 1930, has declined over 21 m from 1930 to 1997 (Shatanawi, 2003) (see also Fig. 5).

9.4 Salt water intrusion

Salt water intrusion is apparent at the coastal shore of Gaza, but not at the coastal basin in the Israeli area because of modern techniques and strategies used to prevent this problem. A specific strategy of recharging the coastal aquifer was adopted using: i) treated wastewater (for example, from the Dan treatment plant), ii) return flows from agriculture, which uses a huge amount of water annually, and iii) water transportation from other areas.

10 Vulnerability

It is expected that by 2025 the average annual renewable water resources for the three countries will fall (Fig. 8, Slide 16) to a critical volume when compared with a world average of 4,780 m³ per capita (Berkoff, 1994). This will be evident in all aquifers of the region except the coastal aquifer which is either not affected or has an increase in water level for other technical reasons.

The aquifers located in the desert areas are non-replenishing and therefore not affected directly by precipitation. The mountain aquifers seem to be the most vulnerable, especially west of the rift fault valley. This decline in water availability will affect the total water use and the water supply which in turn has a direct influence on socio-economic development, as well as on the environment itself (Fig. 9, Slide 18).

It is often assumed that because the Middle East region has very scarce water resources and an arid climate, the impact of climate change would be negligible (IPCC-WGII, 1996).

However, as noted before, water resources in the region are under severe and increasing stress.

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Any alteration in climatic patterns, that would increase temperatures and reduce rainfall, would greatly exacerbate existing difficulties.

Variations in water resources are assumed to impact water prices and agricultural water demand. Impacts on other economic sectors are usually indirect, i.e. through the use of agricultural products and higher water prices. Because water price elasticity is very difficult to estab- lish, extrapolation of current conditions without regard to potential novelties and discontinuities

Figure 8 a) Best and worst case scenario projections of renewable water resources per capita for Israel, Jordan and Palestine; b) Population projections for Israel, Jordan and Palestine

Figure 9 Projected breakdown of water demand (m³x 10⁶) for different sectors in 2025 for Israel, Jordan and Palestine.

m3 x106

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is often used. Due to the semi-arid climate of the region, water can be a limiting factor for development. This indicates that potential welfare impacts could be high.

11 Conclusions and recommendations (Slides 19 and 20)

(i) Traditionally, water resources systems are designed on the assumption that the statistical characteristics of the prevailing climatic and hydrometeorological processes never change (stationary). It is absolutely necessary that future projects are designed, and all projects are operated, taking into account the fact that climate is non-stationary.

(ii) Emergency water resources management and drought mitigation measures must be introduced throughout the area.

(iii) It is necessary to gain a better understanding of the impact of climate change on reser- voirs and aquifers, and this will require a comprehensive and uniform water monitoring programme.

(iv) Assessing water demand requires a better understanding of climate change impacts on soil, vegetation, natural and agricultural ecosystems.

(v) Hydrological and socio-economic studies attempting to predict the gap between supply and demand should not only incorporate social, demographic and political changes, but also the impacts of climate change.

(vi) Water resources have strategic implications and have contributed to conflict in the region. The challenges of water resource management should bring peace not war.

(vii) Identification of areas of potential vulnerability to climate change is essential together with characterization of the potential impacts.

(viii) Future strategies for adaptation to climate change must be identified, including an assessment of their feasibility and development of tactics for the implementation of the most effective strategies.

12 References

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