The Republic of Yemen is located in an arid to semi-arid region. Rainfall rates range from none a... more The Republic of Yemen is located in an arid to semi-arid region. Rainfall rates range from none at certain parts of the country to about 400 mm/yr in its mountainous parts. Rainfall has been harvested and collected in cisterns existed in the mountainous region for generations. In the dry season (October-February), and after the stored water is consumed, people, mainly women and children, have to travel long distances down wadis to fetch water from the nearest water source, which is often not suitable for human consumption. This is the case in the western mountainous region, namely Hajja Governorate, which heavily depends on rainwater for drinking, animal watering, domestic uses and irrigation. However, during the dry season this region experiences foggy conditions. A fog collection field study was carried out in this region to investigate the potential of providing an alternative source for water supply during the dry season. The study consisted of installing 26 standard fog collectors (SFC) of one m² of polypropylene mesh at 19 sites in Hajja, and measuring the daily fogwater amounts collected during the period from 1 January 2003 to 31 March 2003. The results indicated that fog collectors located closest to the red sea with an elevation ranged between 2000-2200 m.a.s.l. and winds from the west direction have produced the highest water output, reaching a maximum of about 4.5 liters per square meter of mesh per day over the three winter months period. The conclusion drawn is that though this technique is cheap, simple and promising, more investigations are still needed on the various parameters contributing to fog collection, such as, relative humidity, temperature, and SFCs technologies.
المتأمل في خارطة حضارات العالم القديمة هو أن معظمها إن لم تقل جميعها، نشأت و نمت و ازدهرت في ظل ت... more المتأمل في خارطة حضارات العالم القديمة هو أن معظمها إن لم تقل جميعها، نشأت و نمت و ازدهرت في ظل تمركزها حول مصادر مائية و أنهار دائمة الجريان. حول هذه المصادر المائية الدائمة نشأت حضارات وادي النيل و بلاد الرافدين و اليونان و غيرها من الحضارات القديمة. غير أن المتأمل في تلك الخارطة كذلك يلاحظ استثناء شبه وحيد على ما سبق قوله من نشوء الحضارات القديمة حول الأنهار و مصادر المياه دائمة الجريان، هذا الاستثناء تمثله الحضارة اليمنية القديمة التي نشأت في الجزء الجنوبي من شبه الجزيرة العربية، حيث لا أنهار و لا مياه دائمة الجريان، إلا قطرات مطر تجود بها السماء، تتجمع في وديانها على شكل سيول، حسن اليمنيون القدماء استغلالها، و لم يتركوها كسالف عهدها تذهب هدراً نحو البحر، أو تبتلعها الصحراء. لقد ترقب اليمنيون القدماء ما تهبه السماء من أمطار ثم ما تشكله من سيول تمر بأوديتهم، فكانوا لها بالمرصاد فهي و الحياة بالنسبة إليهم سواء، تلقفوها بمنشآت و نظم ريّ مبتكرة لم يسبقهم بمثلها في ما نعلم أحد، فكانت السدود و القنوات على أوديتهم و كانت الصهاريج و الخزانات على جبالهم، تحكموا في مسارات السيول، و ثقبوا الجبال لتذهب 1 هذه الدراسة نشرت كفصل في كتاب " نوافذ على الماء و الحضارة في بلاد العرب" من منشورات المنظمة العربية للتربية و الثقافة و العلوم. 2 حالياً: المدير العام المساعد/ المنظمة العربية للتربية و الثقافة و العلوم. البريد الالكتروني: [email protected] السيول و مساقط الأمطار نحوها يريدون للسقية، فصنعوا بها و من خلالها حضارتهم فكانت مساكنهم كما وصفها القرآن الكريم ) لقد كان لسبأ في مسكنهم آية، جنتان عن يمين و شمال كلوا من رزق ربكم و اشكروا له بلدة طيبة و .) رب غفور( )سورة سبأ الآية
There is a large number of water related meetings taking place in the MENA Region each year. This... more There is a large number of water related meetings taking place in the MENA Region each year. This is not surprising in a region where this essential resource for ensuring livelihoods is scarce. The shortage of water is a technicality for the rich countries in the region. Most of the countries on the Arabian Peninsula invest in desalination and create “new water”. It is a response to a limitation in local conditions, which also provide these countries with great wealth through its oil reserves. This does not apply to all countries in the region. The poorer countries, without large oil deposits, rely on their agriculture as the main source of income to the state, with contributions from foreign development aid and retributions from their nationals working elsewhere. For these countries there is little margin for error and no (financial) space for experimenting. Innovative solutions in groundwater management need to be sustainable and preferably self-sustaining even in the short run, since capital for investment is often lacking and money for running facilities is uncertain. Aquifers – most of which straddle international boundaries – are of major strategic importance. Underground aquifers are often the only natural source of water in arid and semi-arid areas and therefore in most of the MENA region – 95% of freshwater withdrawal in Saudi Arabia (2006), 73% in Tunisia (2001) and 65% in Jordan (2005)1. Irrigation systems also depend largely on groundwater resources in many countries – 90% in Libya. Increased use of water due to population and economic growth and a reduction in recharge due to climate change will lead to an increasing pressure on the available water – innovation is needed.
ABSTRACT
An ecohydrological-erosion model for semi-arid mountain catchment has been
developed and... more ABSTRACT An ecohydrological-erosion model for semi-arid mountain catchment has been developed and integrated with rainfall-runoff model for estimating upland delivery rates of sediments resulted from individual storm at the outlet of Wadi Surdud catchment (2370 km2), Tihama, Yemen. The degradation of soil resources in the mountainous areas of Yemen is evident due to long-term and intensive human impacts on those vulnerable ecological environments of the indigenous terraces. If current trends continue, Yemen may permanently lose a significant portion of its productive land to soil erosion due to lack of preservation of indigenous soil and water conservation systems. This area has been degraded into nearly desert-like condition. Yet, geological and even historic data indicate that the natural ecological environments should be much better than it appears. To restore the ecological environment, we need to know its potentials. The erosion and sedimentation processes of the upland watersheds have to be assessed by means which do not rely on historical storm flow data. Methods that depend on available or measurable representative data were developed for a deterministic approach of the erosion process. This study takes advantage of physically based methods and Geographic Information Systems (GIS) and uses the Digital Elevation Model (DEM) and observed meteorological and hydrological data to model the runoff and sediment yield in an attempt to assess the potential natural ecological environments. Our results show that the effective Curve Number (CN) and soil detachability are the factors that determine the potential natural ecological environments. In this paper the study of runoff and sediment delivery is based on one stream gauging station and 10 rainfall gauging stations. Discharge was calculated for the period from July, 15, 1998 to October, 10, 1998 which resulted from 10 rainfall storms. A comparison of observed and predicted sediment yield shows a good agreement with a coefficient of determination of 0.85. Key words: Civil Engineering, Ecohydrology, erosion modeling, wadi, GIS.
The purpose of this study is to assess climate change impacts on water resources and water manage... more The purpose of this study is to assess climate change impacts on water resources and water management in Wadi Surdud drainage basin area, under certain climate change scenarios, and to identify the required and adequate measures and adaptation strategies that can be applied in such area. Wadi Surdud drainage basin constitutes one part of the western drainage basins area of Yemen. It occupies a surface area of nearly 4050 km2, and is featured by an arid/semi-arid climate. The average rainfall in the drainage basin is reported to be between 200 mm and 400 mm, for the upper and middle catchment areas, respectively, but is significantly less in the Tihama part (around 100 mm). Presently, Water resources in the area suffer from an escalating pressure, due to the high consumption of water by agriculture activities, to cope with the increasing demand by population in cities. Therefore, a reduction in rainfall, as a result of climate change, will make the situation even worst. In this study, a Water Evaluation and Planning software (WEAP) was used to evaluate water demands, supplies and scarcity, among all water users under a range of potential climate change scenarios and adaptation strategies. The simulation period in this study was twenty five years (2008-2033) and the adapted strategies and measures were the Rehabilitation of traditional irrigation channels, Conveying irrigation water through closed conduits, the use of drip irrigation method, and changing crop patterns. The simulation results, showed an improvement in irrigation efficiency through the use of drip irrigation technique, proving to be the best strategy that can be adapted by farmers, followed by the use of closed conduits for conveying irrigation water to farms, and then the least preferred strategy, called the rehabilitation of traditional irrigation channels. The strategy, changing crop pattern, was found to have little impact on water savings. The amount of water saved for the preferred adapted strategies, the use of drip irrigation and use of closed conduits, are 157.3 MCM/y and 91 MCM/y, respectively.
Yemen faces formidable freshwater management challenges. Devising policies for sustainable use an... more Yemen faces formidable freshwater management challenges. Devising policies for sustainable use and allocation of limited water resources is made difficult by substantial population growth, degrading environmental quality and uncertainty regarding possible changes in water availability due to climate change. We use the Water Resources Evaluation and Planning software to evaluate water needs and scarcity for three case study areas in Yemen representing different ecological conditions (Sana'a, Sadah, and Aden City) under a range of scenarios that include potential climate change and adaptation strategies. These management strategies, identified by stakeholder processes, have the potential to reduce vulnerability and build resilience. The modelled results suggest that current and predicted patterns of water consumption will soon fully deplete available supplies, and are a bigger driver of vulnerability than potential climate change for the region. In the absence of new strategies to bring into balance water supply and demand patterns, results for all three case studies suggest the pressing water crisis will only worsen. Timely interventions, designed to build resilience to scarcity, are urgently needed.
The Republic of Yemen is located in an arid to semi-arid region. Rainfall rates range from none a... more The Republic of Yemen is located in an arid to semi-arid region. Rainfall rates range from none at certain parts of the country to about 400 mm/yr in its mountainous parts. Rainfall has been harvested and collected in cisterns existed in the mountainous region for generations. In the dry season (October-February), and after the stored water is consumed, people, mainly women and children, have to travel long distances down wadis to fetch water from the nearest water source, which is often not suitable for human consumption. This is the case in the western mountainous region, namely Hajja Governorate, which heavily depends on rainwater for drinking, animal watering, domestic uses and irrigation. However, during the dry season this region experiences foggy conditions. A fog collection field study was carried out in this region to investigate the potential of providing an alternative source for water supply during the dry season. The study consisted of installing 26 standard fog collectors (SFC) of one m² of polypropylene mesh at 19 sites in Hajja, and measuring the daily fogwater amounts collected during the period from 1 January 2003 to 31 March 2003. The results indicated that fog collectors located closest to the red sea with an elevation ranged between 2000-2200 m.a.s.l. and winds from the west direction have produced the highest water output, reaching a maximum of about 4.5 liters per square meter of mesh per day over the three winter months period. The conclusion drawn is that though this technique is cheap, simple and promising, more investigations are still needed on the various parameters contributing to fog collection, such as, relative humidity, temperature, and SFCs technologies.
المتأمل في خارطة حضارات العالم القديمة هو أن معظمها إن لم تقل جميعها، نشأت و نمت و ازدهرت في ظل ت... more المتأمل في خارطة حضارات العالم القديمة هو أن معظمها إن لم تقل جميعها، نشأت و نمت و ازدهرت في ظل تمركزها حول مصادر مائية و أنهار دائمة الجريان. حول هذه المصادر المائية الدائمة نشأت حضارات وادي النيل و بلاد الرافدين و اليونان و غيرها من الحضارات القديمة. غير أن المتأمل في تلك الخارطة كذلك يلاحظ استثناء شبه وحيد على ما سبق قوله من نشوء الحضارات القديمة حول الأنهار و مصادر المياه دائمة الجريان، هذا الاستثناء تمثله الحضارة اليمنية القديمة التي نشأت في الجزء الجنوبي من شبه الجزيرة العربية، حيث لا أنهار و لا مياه دائمة الجريان، إلا قطرات مطر تجود بها السماء، تتجمع في وديانها على شكل سيول، حسن اليمنيون القدماء استغلالها، و لم يتركوها كسالف عهدها تذهب هدراً نحو البحر، أو تبتلعها الصحراء. لقد ترقب اليمنيون القدماء ما تهبه السماء من أمطار ثم ما تشكله من سيول تمر بأوديتهم، فكانوا لها بالمرصاد فهي و الحياة بالنسبة إليهم سواء، تلقفوها بمنشآت و نظم ريّ مبتكرة لم يسبقهم بمثلها في ما نعلم أحد، فكانت السدود و القنوات على أوديتهم و كانت الصهاريج و الخزانات على جبالهم، تحكموا في مسارات السيول، و ثقبوا الجبال لتذهب 1 هذه الدراسة نشرت كفصل في كتاب " نوافذ على الماء و الحضارة في بلاد العرب" من منشورات المنظمة العربية للتربية و الثقافة و العلوم. 2 حالياً: المدير العام المساعد/ المنظمة العربية للتربية و الثقافة و العلوم. البريد الالكتروني: [email protected] السيول و مساقط الأمطار نحوها يريدون للسقية، فصنعوا بها و من خلالها حضارتهم فكانت مساكنهم كما وصفها القرآن الكريم ) لقد كان لسبأ في مسكنهم آية، جنتان عن يمين و شمال كلوا من رزق ربكم و اشكروا له بلدة طيبة و .) رب غفور( )سورة سبأ الآية
There is a large number of water related meetings taking place in the MENA Region each year. This... more There is a large number of water related meetings taking place in the MENA Region each year. This is not surprising in a region where this essential resource for ensuring livelihoods is scarce. The shortage of water is a technicality for the rich countries in the region. Most of the countries on the Arabian Peninsula invest in desalination and create “new water”. It is a response to a limitation in local conditions, which also provide these countries with great wealth through its oil reserves. This does not apply to all countries in the region. The poorer countries, without large oil deposits, rely on their agriculture as the main source of income to the state, with contributions from foreign development aid and retributions from their nationals working elsewhere. For these countries there is little margin for error and no (financial) space for experimenting. Innovative solutions in groundwater management need to be sustainable and preferably self-sustaining even in the short run, since capital for investment is often lacking and money for running facilities is uncertain. Aquifers – most of which straddle international boundaries – are of major strategic importance. Underground aquifers are often the only natural source of water in arid and semi-arid areas and therefore in most of the MENA region – 95% of freshwater withdrawal in Saudi Arabia (2006), 73% in Tunisia (2001) and 65% in Jordan (2005)1. Irrigation systems also depend largely on groundwater resources in many countries – 90% in Libya. Increased use of water due to population and economic growth and a reduction in recharge due to climate change will lead to an increasing pressure on the available water – innovation is needed.
ABSTRACT
An ecohydrological-erosion model for semi-arid mountain catchment has been
developed and... more ABSTRACT An ecohydrological-erosion model for semi-arid mountain catchment has been developed and integrated with rainfall-runoff model for estimating upland delivery rates of sediments resulted from individual storm at the outlet of Wadi Surdud catchment (2370 km2), Tihama, Yemen. The degradation of soil resources in the mountainous areas of Yemen is evident due to long-term and intensive human impacts on those vulnerable ecological environments of the indigenous terraces. If current trends continue, Yemen may permanently lose a significant portion of its productive land to soil erosion due to lack of preservation of indigenous soil and water conservation systems. This area has been degraded into nearly desert-like condition. Yet, geological and even historic data indicate that the natural ecological environments should be much better than it appears. To restore the ecological environment, we need to know its potentials. The erosion and sedimentation processes of the upland watersheds have to be assessed by means which do not rely on historical storm flow data. Methods that depend on available or measurable representative data were developed for a deterministic approach of the erosion process. This study takes advantage of physically based methods and Geographic Information Systems (GIS) and uses the Digital Elevation Model (DEM) and observed meteorological and hydrological data to model the runoff and sediment yield in an attempt to assess the potential natural ecological environments. Our results show that the effective Curve Number (CN) and soil detachability are the factors that determine the potential natural ecological environments. In this paper the study of runoff and sediment delivery is based on one stream gauging station and 10 rainfall gauging stations. Discharge was calculated for the period from July, 15, 1998 to October, 10, 1998 which resulted from 10 rainfall storms. A comparison of observed and predicted sediment yield shows a good agreement with a coefficient of determination of 0.85. Key words: Civil Engineering, Ecohydrology, erosion modeling, wadi, GIS.
The purpose of this study is to assess climate change impacts on water resources and water manage... more The purpose of this study is to assess climate change impacts on water resources and water management in Wadi Surdud drainage basin area, under certain climate change scenarios, and to identify the required and adequate measures and adaptation strategies that can be applied in such area. Wadi Surdud drainage basin constitutes one part of the western drainage basins area of Yemen. It occupies a surface area of nearly 4050 km2, and is featured by an arid/semi-arid climate. The average rainfall in the drainage basin is reported to be between 200 mm and 400 mm, for the upper and middle catchment areas, respectively, but is significantly less in the Tihama part (around 100 mm). Presently, Water resources in the area suffer from an escalating pressure, due to the high consumption of water by agriculture activities, to cope with the increasing demand by population in cities. Therefore, a reduction in rainfall, as a result of climate change, will make the situation even worst. In this study, a Water Evaluation and Planning software (WEAP) was used to evaluate water demands, supplies and scarcity, among all water users under a range of potential climate change scenarios and adaptation strategies. The simulation period in this study was twenty five years (2008-2033) and the adapted strategies and measures were the Rehabilitation of traditional irrigation channels, Conveying irrigation water through closed conduits, the use of drip irrigation method, and changing crop patterns. The simulation results, showed an improvement in irrigation efficiency through the use of drip irrigation technique, proving to be the best strategy that can be adapted by farmers, followed by the use of closed conduits for conveying irrigation water to farms, and then the least preferred strategy, called the rehabilitation of traditional irrigation channels. The strategy, changing crop pattern, was found to have little impact on water savings. The amount of water saved for the preferred adapted strategies, the use of drip irrigation and use of closed conduits, are 157.3 MCM/y and 91 MCM/y, respectively.
Yemen faces formidable freshwater management challenges. Devising policies for sustainable use an... more Yemen faces formidable freshwater management challenges. Devising policies for sustainable use and allocation of limited water resources is made difficult by substantial population growth, degrading environmental quality and uncertainty regarding possible changes in water availability due to climate change. We use the Water Resources Evaluation and Planning software to evaluate water needs and scarcity for three case study areas in Yemen representing different ecological conditions (Sana'a, Sadah, and Aden City) under a range of scenarios that include potential climate change and adaptation strategies. These management strategies, identified by stakeholder processes, have the potential to reduce vulnerability and build resilience. The modelled results suggest that current and predicted patterns of water consumption will soon fully deplete available supplies, and are a bigger driver of vulnerability than potential climate change for the region. In the absence of new strategies to bring into balance water supply and demand patterns, results for all three case studies suggest the pressing water crisis will only worsen. Timely interventions, designed to build resilience to scarcity, are urgently needed.
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Papers by Abdulla Noaman
مصادر مائية و أنهار دائمة الجريان. حول هذه المصادر المائية الدائمة نشأت حضارات وادي النيل و بلاد الرافدين و اليونان و
غيرها من الحضارات القديمة.
غير أن المتأمل في تلك الخارطة كذلك يلاحظ استثناء شبه وحيد على ما سبق قوله من نشوء الحضارات القديمة حول الأنهار
و مصادر المياه دائمة الجريان، هذا الاستثناء تمثله الحضارة اليمنية القديمة التي نشأت في الجزء الجنوبي من شبه الجزيرة العربية،
حيث لا أنهار و لا مياه دائمة الجريان، إلا قطرات مطر تجود بها السماء، تتجمع في وديانها على شكل سيول، حسن اليمنيون
القدماء استغلالها، و لم يتركوها كسالف عهدها تذهب هدراً نحو البحر، أو تبتلعها الصحراء.
لقد ترقب اليمنيون القدماء ما تهبه السماء من أمطار ثم
ما تشكله من سيول تمر بأوديتهم، فكانوا لها بالمرصاد فهي
و الحياة بالنسبة إليهم سواء، تلقفوها بمنشآت و نظم ريّ
مبتكرة لم يسبقهم بمثلها في ما نعلم أحد، فكانت السدود
و القنوات على أوديتهم و كانت الصهاريج و الخزانات على
جبالهم، تحكموا في مسارات السيول، و ثقبوا الجبال لتذهب
1 هذه الدراسة نشرت كفصل في كتاب " نوافذ على الماء و الحضارة في بلاد العرب" من منشورات المنظمة العربية للتربية و الثقافة و العلوم.
2 حالياً: المدير العام المساعد/ المنظمة العربية للتربية و الثقافة و العلوم.
البريد الالكتروني: [email protected]
السيول و مساقط الأمطار نحوها يريدون للسقية، فصنعوا بها
و من خلالها حضارتهم فكانت مساكنهم كما وصفها
القرآن الكريم ) لقد كان لسبأ في مسكنهم آية، جنتان عن
يمين و شمال كلوا من رزق ربكم و اشكروا له بلدة طيبة و
.) رب غفور( )سورة سبأ الآية
surprising in a region where this essential resource for ensuring livelihoods is scarce. The shortage of
water is a technicality for the rich countries in the region. Most of the countries on the Arabian Peninsula
invest in desalination and create “new water”. It is a response to a limitation in local conditions, which
also provide these countries with great wealth through its oil reserves. This does not apply to all countries
in the region. The poorer countries, without large oil deposits, rely on their agriculture as the main source
of income to the state, with contributions from foreign development aid and retributions from their
nationals working elsewhere. For these countries there is little margin for error and no (financial) space for
experimenting. Innovative solutions in groundwater management need to be sustainable and preferably
self-sustaining even in the short run, since capital for investment is often lacking and money for running
facilities is uncertain.
Aquifers – most of which straddle international boundaries – are of major strategic importance.
Underground aquifers are often the only natural source of water in arid and semi-arid areas and therefore
in most of the MENA region – 95% of freshwater withdrawal in Saudi Arabia (2006), 73% in Tunisia
(2001) and 65% in Jordan (2005)1. Irrigation systems also depend largely on groundwater resources in
many countries – 90% in Libya.
Increased use of water due to population and economic growth and a reduction in recharge due to climate
change will lead to an increasing pressure on the available water – innovation is needed.
An ecohydrological-erosion model for semi-arid mountain catchment has been
developed and integrated with rainfall-runoff model for estimating upland delivery
rates of sediments resulted from individual storm at the outlet of Wadi Surdud
catchment (2370 km2), Tihama, Yemen.
The degradation of soil resources in the mountainous areas of Yemen is evident due
to long-term and intensive human impacts on those vulnerable ecological environments
of the indigenous terraces. If current trends continue, Yemen may permanently lose a
significant portion of its productive land to soil erosion due to lack of preservation of
indigenous soil and water conservation systems. This area has been degraded into
nearly desert-like condition. Yet, geological and even historic data indicate that the
natural ecological environments should be much better than it appears. To restore the
ecological environment, we need to know its potentials.
The erosion and sedimentation processes of the upland watersheds have to be
assessed by means which do not rely on historical storm flow data. Methods that
depend on available or measurable representative data were developed for a
deterministic approach of the erosion process.
This study takes advantage of physically based methods and Geographic Information
Systems (GIS) and uses the Digital Elevation Model (DEM) and observed
meteorological and hydrological data to model the runoff and sediment yield in an
attempt to assess the potential natural ecological environments. Our results show that
the effective Curve Number (CN) and soil detachability are the factors that determine
the potential natural ecological environments.
In this paper the study of runoff and sediment delivery is based on one stream
gauging station and 10 rainfall gauging stations. Discharge was calculated for the
period from July, 15, 1998 to October, 10, 1998 which resulted from 10 rainfall storms.
A comparison of observed and predicted sediment yield shows a good agreement
with a coefficient of determination of 0.85.
Key words: Civil Engineering, Ecohydrology, erosion modeling, wadi, GIS.
hydrochemically. The aim of this paper is to analyse and conceptualise vertical transport mechanisms taking place in an urban area of
extensive wastewater infiltration by analysing and combining the water balance, the microbial (Escherichia coli) mass balance, and the
mass balance for dissolved solutes. For this, data on sediment characteristics (grain size, organic carbon, reactive iron, and calcite),
groundwater levels, and concentrations of E. coli in groundwater and waste water were collected. In the laboratory, data on E. coli decay
rate coefficients, and on bacteria retention characteristics of the sediment were collected via column experiments. The results indicated
that shallow groundwater, at depths of 50 m below the surface, was contaminated with E. coli concentrations as high as 106 CFU/
100 mL. In general, E. coli concentrations decreased only 3 log units from the point of infiltration to shallow groundwater.
Concentrations were lower at greater depths in the aquifer. In laboratory columns of disturbed sediments, bacteria removal was 2–5 log
units/0.5 cm column sediment. Because of the relatively high E. coli concentrations in the shallow aquifer, transport had likely taken
place via a connected network of pores with a diameter large enough to allowbacterial transport instead of via the sediment matrix,which
was inaccessible for bacteria, as was clear from the column experiments. The decay rate coefficient was determined from laboratory
microcosms to be 0.15 d−1. Assuming that decay in the aquifer was similar to decay in the laboratory, then the pore water flow velocity
between the point of infiltration and shallow groundwater, coinciding with a concentration decrease of 3 log units, was 0.38 m/d, and
therefore, transport in this connected network of pores was fast. According to the water balance of the alluvial aquifer, determined from
transient groundwater modelling, groundwater flow in the aquifer was mainly in vertical downward direction, and therefore, the mass
balance for dissolved solutes was simulated using a 1D transport model of a 200 m column of the Quaternary Alluvium aquifer. The
model, constructed with PHREEQC, included dual porosity, and was able to adequately simulate removal of E. coli, cation-exchange,
and nitrification. The added value of the use of E. coli in this study was the recognition of relatively fast transport velocities occurring in
the aquifer, and the necessity to use the dual porosity concept to investigate vertical transport mechanisms. Therefore, in general and if
possible, microbial mass balances should be considered more systematically as an integral part of transport studies.
© 2007 Elsevier B.V. All rights reserved.
The simulation period in this study was twenty five years (2008-2033) and the adapted strategies and measures were the Rehabilitation of traditional irrigation channels, Conveying irrigation water through closed conduits, the use of drip irrigation method, and changing crop patterns. The simulation results, showed an improvement in irrigation efficiency through the use of drip irrigation technique, proving to be the best strategy that can be adapted by farmers, followed by the use of closed conduits for conveying irrigation water to farms, and then the least preferred strategy, called the rehabilitation of traditional irrigation channels. The strategy, changing crop pattern, was found to have little impact on water savings. The amount of water saved for the preferred adapted strategies, the use of drip irrigation and use of closed conduits, are 157.3 MCM/y and 91 MCM/y, respectively.
مصادر مائية و أنهار دائمة الجريان. حول هذه المصادر المائية الدائمة نشأت حضارات وادي النيل و بلاد الرافدين و اليونان و
غيرها من الحضارات القديمة.
غير أن المتأمل في تلك الخارطة كذلك يلاحظ استثناء شبه وحيد على ما سبق قوله من نشوء الحضارات القديمة حول الأنهار
و مصادر المياه دائمة الجريان، هذا الاستثناء تمثله الحضارة اليمنية القديمة التي نشأت في الجزء الجنوبي من شبه الجزيرة العربية،
حيث لا أنهار و لا مياه دائمة الجريان، إلا قطرات مطر تجود بها السماء، تتجمع في وديانها على شكل سيول، حسن اليمنيون
القدماء استغلالها، و لم يتركوها كسالف عهدها تذهب هدراً نحو البحر، أو تبتلعها الصحراء.
لقد ترقب اليمنيون القدماء ما تهبه السماء من أمطار ثم
ما تشكله من سيول تمر بأوديتهم، فكانوا لها بالمرصاد فهي
و الحياة بالنسبة إليهم سواء، تلقفوها بمنشآت و نظم ريّ
مبتكرة لم يسبقهم بمثلها في ما نعلم أحد، فكانت السدود
و القنوات على أوديتهم و كانت الصهاريج و الخزانات على
جبالهم، تحكموا في مسارات السيول، و ثقبوا الجبال لتذهب
1 هذه الدراسة نشرت كفصل في كتاب " نوافذ على الماء و الحضارة في بلاد العرب" من منشورات المنظمة العربية للتربية و الثقافة و العلوم.
2 حالياً: المدير العام المساعد/ المنظمة العربية للتربية و الثقافة و العلوم.
البريد الالكتروني: [email protected]
السيول و مساقط الأمطار نحوها يريدون للسقية، فصنعوا بها
و من خلالها حضارتهم فكانت مساكنهم كما وصفها
القرآن الكريم ) لقد كان لسبأ في مسكنهم آية، جنتان عن
يمين و شمال كلوا من رزق ربكم و اشكروا له بلدة طيبة و
.) رب غفور( )سورة سبأ الآية
surprising in a region where this essential resource for ensuring livelihoods is scarce. The shortage of
water is a technicality for the rich countries in the region. Most of the countries on the Arabian Peninsula
invest in desalination and create “new water”. It is a response to a limitation in local conditions, which
also provide these countries with great wealth through its oil reserves. This does not apply to all countries
in the region. The poorer countries, without large oil deposits, rely on their agriculture as the main source
of income to the state, with contributions from foreign development aid and retributions from their
nationals working elsewhere. For these countries there is little margin for error and no (financial) space for
experimenting. Innovative solutions in groundwater management need to be sustainable and preferably
self-sustaining even in the short run, since capital for investment is often lacking and money for running
facilities is uncertain.
Aquifers – most of which straddle international boundaries – are of major strategic importance.
Underground aquifers are often the only natural source of water in arid and semi-arid areas and therefore
in most of the MENA region – 95% of freshwater withdrawal in Saudi Arabia (2006), 73% in Tunisia
(2001) and 65% in Jordan (2005)1. Irrigation systems also depend largely on groundwater resources in
many countries – 90% in Libya.
Increased use of water due to population and economic growth and a reduction in recharge due to climate
change will lead to an increasing pressure on the available water – innovation is needed.
An ecohydrological-erosion model for semi-arid mountain catchment has been
developed and integrated with rainfall-runoff model for estimating upland delivery
rates of sediments resulted from individual storm at the outlet of Wadi Surdud
catchment (2370 km2), Tihama, Yemen.
The degradation of soil resources in the mountainous areas of Yemen is evident due
to long-term and intensive human impacts on those vulnerable ecological environments
of the indigenous terraces. If current trends continue, Yemen may permanently lose a
significant portion of its productive land to soil erosion due to lack of preservation of
indigenous soil and water conservation systems. This area has been degraded into
nearly desert-like condition. Yet, geological and even historic data indicate that the
natural ecological environments should be much better than it appears. To restore the
ecological environment, we need to know its potentials.
The erosion and sedimentation processes of the upland watersheds have to be
assessed by means which do not rely on historical storm flow data. Methods that
depend on available or measurable representative data were developed for a
deterministic approach of the erosion process.
This study takes advantage of physically based methods and Geographic Information
Systems (GIS) and uses the Digital Elevation Model (DEM) and observed
meteorological and hydrological data to model the runoff and sediment yield in an
attempt to assess the potential natural ecological environments. Our results show that
the effective Curve Number (CN) and soil detachability are the factors that determine
the potential natural ecological environments.
In this paper the study of runoff and sediment delivery is based on one stream
gauging station and 10 rainfall gauging stations. Discharge was calculated for the
period from July, 15, 1998 to October, 10, 1998 which resulted from 10 rainfall storms.
A comparison of observed and predicted sediment yield shows a good agreement
with a coefficient of determination of 0.85.
Key words: Civil Engineering, Ecohydrology, erosion modeling, wadi, GIS.
hydrochemically. The aim of this paper is to analyse and conceptualise vertical transport mechanisms taking place in an urban area of
extensive wastewater infiltration by analysing and combining the water balance, the microbial (Escherichia coli) mass balance, and the
mass balance for dissolved solutes. For this, data on sediment characteristics (grain size, organic carbon, reactive iron, and calcite),
groundwater levels, and concentrations of E. coli in groundwater and waste water were collected. In the laboratory, data on E. coli decay
rate coefficients, and on bacteria retention characteristics of the sediment were collected via column experiments. The results indicated
that shallow groundwater, at depths of 50 m below the surface, was contaminated with E. coli concentrations as high as 106 CFU/
100 mL. In general, E. coli concentrations decreased only 3 log units from the point of infiltration to shallow groundwater.
Concentrations were lower at greater depths in the aquifer. In laboratory columns of disturbed sediments, bacteria removal was 2–5 log
units/0.5 cm column sediment. Because of the relatively high E. coli concentrations in the shallow aquifer, transport had likely taken
place via a connected network of pores with a diameter large enough to allowbacterial transport instead of via the sediment matrix,which
was inaccessible for bacteria, as was clear from the column experiments. The decay rate coefficient was determined from laboratory
microcosms to be 0.15 d−1. Assuming that decay in the aquifer was similar to decay in the laboratory, then the pore water flow velocity
between the point of infiltration and shallow groundwater, coinciding with a concentration decrease of 3 log units, was 0.38 m/d, and
therefore, transport in this connected network of pores was fast. According to the water balance of the alluvial aquifer, determined from
transient groundwater modelling, groundwater flow in the aquifer was mainly in vertical downward direction, and therefore, the mass
balance for dissolved solutes was simulated using a 1D transport model of a 200 m column of the Quaternary Alluvium aquifer. The
model, constructed with PHREEQC, included dual porosity, and was able to adequately simulate removal of E. coli, cation-exchange,
and nitrification. The added value of the use of E. coli in this study was the recognition of relatively fast transport velocities occurring in
the aquifer, and the necessity to use the dual porosity concept to investigate vertical transport mechanisms. Therefore, in general and if
possible, microbial mass balances should be considered more systematically as an integral part of transport studies.
© 2007 Elsevier B.V. All rights reserved.
The simulation period in this study was twenty five years (2008-2033) and the adapted strategies and measures were the Rehabilitation of traditional irrigation channels, Conveying irrigation water through closed conduits, the use of drip irrigation method, and changing crop patterns. The simulation results, showed an improvement in irrigation efficiency through the use of drip irrigation technique, proving to be the best strategy that can be adapted by farmers, followed by the use of closed conduits for conveying irrigation water to farms, and then the least preferred strategy, called the rehabilitation of traditional irrigation channels. The strategy, changing crop pattern, was found to have little impact on water savings. The amount of water saved for the preferred adapted strategies, the use of drip irrigation and use of closed conduits, are 157.3 MCM/y and 91 MCM/y, respectively.