In this study, performance assessment of a residential scale size solar thermal driven adsorption cooling system installed in hot arid and dusty area at Upper Egypt, and, in operation since summer 2012 until now is carried out experimentally for four years in operation, moreover, the gained operational experiences are presented. The system performance is expressed in term of the solar collectors' field thermal efficiency, actual chiller chilling capacity, the temperature of cold-water outlet from the chiller, chiller coefficient of performance (COP) and cooling-water temperature outlet from the cooling tower. The system performance results show that the daily solar collector efficiency during the reported period was ranged from about 50% to 78%. While, the average chiller COP was varied from 0.4 to 0.64 in combination with average chilling power ranged from 3.6 to 6.42 kW and average chiller outlet cold water temperature ranged from 19 °C to 12.12 °C correspondence to cooling tower outlet cooling water temperature ranged from 31.4 °C to 23.4 °C, respectively. In the cooling session of 2014, a 50 kW cooling capacity wet cooling tower is integrated into the system, and the measurements show that the outlet water temperature from the cooling tower is about 23.4 °C at ambient air dry bulb temperature of 35.7 °C and wet bulb temperature of about 19 °C. Consequently, under this new heat rejection condition, the chiller average cooling capacity and COP reaches were 6.42 kW and 0.64 with a chilled water temperature of 15 °C. Clearly from the system operation period, the heat rejection through the re-cooling sub-system has the main significant impact on the system performance in the hot arid areas. Therefore, it should be based on alternative heat sink recourses with appropriate cost performance techniques.

Being a country with limited freshwater resources, Yemen facing a water crisis due to rapid depletion of groundwater and the lack of surface water availability. Dhamar governorate, which is located about 100 km from the south of Sana'a (the capital), is one of the arid regions in the country. This research aims to explain the current situation of water resources and to get better planning for water resources management in the governorate. The rainfall is low and have spatial and temporal variation as well as the non-renewable groundwater abstraction is high. Previous studies in Dhamar plain showed that the total inflow and outflow were approximately 659.36 and 771.51 MCM/year respectively, which gives negative change in storage of about 112.15 MCM/year. Groundwater table declined in the last 40 years at a rate of 2.0 to 2.5 m/year, because of the high abstraction of groundwater from the entire area. It is predicted with the growth rate of 2% in water abstraction, which is normally expected in developing the economy, the shallow groundwater would be exhausted within the next 30 years. In Dhamar plain, it was found that the irrigation supply for irrigated areas of single, double and perennial crops were about 90, 95 and 95% from groundwater while the remaining percentage supplied from surface water. In general, the classification of cultivated area according to the sources of irrigation not only in Dhamar plain but in all the governorate in 2013 was about 27 and 73% from groundwater and surface water respectively, which was changed in 2015 to 39 and 61% respectively. This means that there is a probability stress on groundwater in the future in agriculture sector. Better water resources management and conservation with planning are very important to apply in the governorate to solve the problem of water shortage in the future and conserve the non-renewable water resources. From this study, different scenarios suggested to adopt with the scarce in water resources.

Being a country with limited freshwater resources, Yemen facing a water crisis due to rapid depletion of groundwater and the lack of surface water availability. Dhamar governorate, which is located about 100 km from the south of Sana'a (the capital), is one of the arid regions in the country. This research aims to explain the current situation of water resources and to get better planning for water resources management in the governorate. The rainfall is low and have spatial and temporal variation as well as the non-renewable groundwater abstraction is high. Previous studies in Dhamar plain showed that the total inflow and outflow were approximately 659.36 and 771.51 MCM/year respectively, which gives negative change in storage of about 112.15 MCM/year. Groundwater table declined in the last 40 years at a rate of 2.0 to 2.5 m/year, because of the high abstraction of groundwater from the entire area. It is predicted with the growth rate of 2% in water abstraction, which is normally expected in developing the economy, the shallow groundwater would be exhausted within the next 30 years. In Dhamar plain, it was found that the irrigation supply for irrigated areas of single, double and perennial crops were about 90, 95 and 95% from groundwater while the remaining percentage supplied from surface water. In general, the classification of cultivated area according to the sources of irrigation not only in Dhamar plain but in all the governorate in 2013 was about 27 and 73% from groundwater and surface water respectively, which was changed in 2015 to 39 and 61% respectively. This means that there is a probability stress on groundwater in the future in agriculture sector. Better water resources management and conservation with planning are very important to apply in the governorate to solve the problem of water shortage in the future and conserve the non-renewable water resources. From this study, different scenarios suggested to adopt with the scarce in water resources.

Being a country with limited freshwater resources, Yemen facing a water crisis due to rapid depletion of groundwater and the lack of surface water availability. Dhamar governorate, which is located about 100 km from the south of Sana'a (the capital), is one of the arid regions in the country. This research aims to explain the current situation of water resources and to get better planning for water resources management in the governorate. The rainfall is low and have spatial and temporal variation as well as the non-renewable groundwater abstraction is high. Previous studies in Dhamar plain showed that the total inflow and outflow were approximately 659.36 and 771.51 MCM/year respectively, which gives negative change in storage of about 112.15 MCM/year. Groundwater table declined in the last 40 years at a rate of 2.0 to 2.5 m/year, because of the high abstraction of groundwater from the entire area. It is predicted with the growth rate of 2% in water abstraction, which is normally expected in developing the economy, the shallow groundwater would be exhausted within the next 30 years. In Dhamar plain, it was found that the irrigation supply for irrigated areas of single, double and perennial crops were about 90, 95 and 95% from groundwater while the remaining percentage supplied from surface water. In general, the classification of cultivated area according to the sources of irrigation not only in Dhamar plain but in all the governorate in 2013 was about 27 and 73% from groundwater and surface water respectively, which was changed in 2015 to 39 and 61% respectively. This means that there is a probability stress on groundwater in the future in agriculture sector. Better water resources management and conservation with planning are very important to apply in the governorate to solve the problem of water shortage in the future and conserve the non-renewable water resources. From this study, different scenarios suggested to adopt with the scarce in water resources.

In such problematic water situation in Egypt, control and saving of the available limited quantity takes great importance from both technical and national points of view. In addition to all the well-known traditional reasons of the problem such as pollution, over usage, and bad traditions of dealing with water, a new very important reason is added nowadays, called "Climate Changes" which has a direct impact on sea water rising, that causes a serious attack of the salt water to the fresh water especially in River Deltas., Not only the surface water, but also the ground water. Since that process proved some acceleration, several investigations have recently considered the worst impacts of climate change and sea water level rise on sea water intrusion. Most of them have revealed the severity of such problem, and the significance of the land movement of the dispersion zone under the sea water level rise situation. In this paper, we try to introduce a technical review and study for the most popular studies concerning our topic, and its most important conclusions, as an approach for preparing the Ph.D. thesis about the Nile Delta water equilibrium in the light of the expected Mediterranean Sea water level rise. Nile Delta, which located between Damietta Branch on the East, and Rosetta Branch on the west, occupies about 20000 square kilometers of the most rich, productive land in Egypt. About 50% of Egyptian population live in that area, agriculture is the main human activities on them, so water is the prime factor in their life, and their agriculture investments. The great amount of this investment depends on the ground water, which faces a serious challenge due to, two reasons, first, is the overuse, and over pumping, while the second is the attack of the salt water due to the Mediterranean Seawater level rise, because of the climate changes. These two reasons must be overcome, if the first reason can be controlled by law, and technical roles, the second reason needs intensive studies and investigations concerning the interaction between seawater and fresh ground water.

In such problematic water situation in Egypt, control and saving of the available limited quantity takes great importance from both technical and national points of view. In addition to all the well-known traditional reasons of the problem such as pollution, over usage, and bad traditions of dealing with water, a new very important reason is added nowadays, called "Climate Changes" which has a direct impact on sea water rising, that causes a serious attack of the salt water to the fresh water especially in River Deltas., Not only the surface water, but also the ground water. Since that process proved some acceleration, several investigations have recently considered the worst impacts of climate change and sea water level rise on sea water intrusion. Most of them have revealed the severity of such problem, and the significance of the land movement of the dispersion zone under the sea water level rise situation. In this paper, we try to introduce a technical review and study for the most popular studies concerning our topic, and its most important conclusions, as an approach for preparing the Ph.D. thesis about the Nile Delta water equilibrium in the light of the expected Mediterranean Sea water level rise. Nile Delta, which located between Damietta Branch on the East, and Rosetta Branch on the west, occupies about 20000 square kilometers of the most rich, productive land in Egypt. About 50% of Egyptian population live in that area, agriculture is the main human activities on them, so water is the prime factor in their life, and their agriculture investments. The great amount of this investment depends on the ground water, which faces a serious challenge due to, two reasons, first, is the overuse, and over pumping, while the second is the attack of the salt water due to the Mediterranean Seawater level rise, because of the climate changes. These two reasons must be overcome, if the first reason can be controlled by law, and technical roles, the second reason needs intensive studies and investigations concerning the interaction between seawater and fresh ground water.

Since inclined headwalls proved promising good results in increasing the performance efficiency of the under-desert road culverts, and so protecting such roads against overtopping and flooding (Ashour et al., 2016). Using headwalls with inclination angle less than 45° will be so expensive due to its big length for reaching the water levels, so in this experimental study, we present a trial for introducing an economical solution for using such inclined headwalls, to score the two needed goals (more culvert performance efficiency, for desert roads protection and at the same time, with minimum cost). The technical idea tested here is to use a broken headwall consists of two parts; the first part is an inclined part just over the top point of the culvert, while the second part which will be over that inclined part will be vertical and extends some distance over the water surface. This study is divided into two trends, the first one is focusing on obtaining the optimum inclination angle (θ), of the inclined lower part of the tested headwall, and the second trend concerns with the length (L) of that inclined part (as a function of the culvert inside height "d") after which the vertical part begins. Six angles of inclination ranging from 15° to 90° were tested in addition to the culvert without any headwalls (projected culvert) as a reference. In the second pivot, five models of broken headwalls of lower inclined part of length ranging as L/d = 0.5, 1.0, 1.5, 2.0, and 2.5 were examined with the recommended inclination angle. Experiments carried out using the introduced new shape of the headwall in both upstream and downstream sides (at the entrance and exit of the culvert). Through a total of 315 experimental runs, 30° inclination angle for the introduced headwall in both culvert's entrance and exit, proved the best among all the tested angles. Also, the relative length of the inclined part (L/d) =2.5 showed the best economic relative length for the lower inclined part among all the tested relative lengths.

Since inclined headwalls proved promising good results in increasing the performance efficiency of the under-desert road culverts, and so protecting such roads against overtopping and flooding (Ashour et al., 2016). Using headwalls with inclination angle less than 45° will be so expensive due to its big length for reaching the water levels, so in this experimental study, we present a trial for introducing an economical solution for using such inclined headwalls, to score the two needed goals (more culvert performance efficiency, for desert roads protection and at the same time, with minimum cost). The technical idea tested here is to use a broken headwall consists of two parts; the first part is an inclined part just over the top point of the culvert, while the second part which will be over that inclined part will be vertical and extends some distance over the water surface. This study is divided into two trends, the first one is focusing on obtaining the optimum inclination angle (θ), of the inclined lower part of the tested headwall, and the second trend concerns with the length (L) of that inclined part (as a function of the culvert inside height "d") after which the vertical part begins. Six angles of inclination ranging from 15° to 90° were tested in addition to the culvert without any headwalls (projected culvert) as a reference. In the second pivot, five models of broken headwalls of lower inclined part of length ranging as L/d = 0.5, 1.0, 1.5, 2.0, and 2.5 were examined with the recommended inclination angle. Experiments carried out using the introduced new shape of the headwall in both upstream and downstream sides (at the entrance and exit of the culvert). Through a total of 315 experimental runs, 30° inclination angle for the introduced headwall in both culvert's entrance and exit, proved the best among all the tested angles. Also, the relative length of the inclined part (L/d) =2.5 showed the best economic relative length for the lower inclined part among all the tested relative lengths.

The compatibility between the needed structural designed dimensions of the irrigation works and the dimensions of the water stream or the canal in which the irrigation work will be located has a great importance from more than one point of view. As it is well known, the main aim of the designer of such works is to reach the optimum design for maximum performance efficiency with economical cost, and minimize negative technical impacts that may be harmful to the safety of the whole work. Since the complete suitability between the obtained designed dimensions of the different construction elements of the work, and the original properties and dimensions of the canal in which the work will be constructed, is rarely occurring. The designer always has to make some changes in the original engineering properties and dimensions of canals, such as bed width, bed level, and/or inside side slope, to reach the needed suitable compatibility between the structural design and the natural original canal cross section. For the economical purposes, the design always needs less width of the work, than the width of the bed of the original stream cross section, so a contraction may be needed where the work will be constructed; the literature indicated that, such a contraction must not be less than 0.6 of the original bed width. That contraction, of course, has a direct impact on the different hydraulic parameters, such as water depth, velocity, and flow regime in the location of the work. Changes of such hydraulic parameters may exceed their safe permissible values, and so the whole structure may face some dangerous situations, which must be overcome. In this paper, we present a technical survey of the previous research concerning canal width contraction, with the needed technical comments, and comparisons as a logical approach for a master-thesis under the same title.

The compatibility between the needed structural designed dimensions of the irrigation works and the dimensions of the water stream or the canal in which the irrigation work will be located has a great importance from more than one point of view. As it is well known, the main aim of the designer of such works is to reach the optimum design for maximum performance efficiency with economical cost, and minimize negative technical impacts that may be harmful to the safety of the whole work. Since the complete suitability between the obtained designed dimensions of the different construction elements of the work, and the original properties and dimensions of the canal in which the work will be constructed, is rarely occurring. The designer always has to make some changes in the original engineering properties and dimensions of canals, such as bed width, bed level, and/or inside side slope, to reach the needed suitable compatibility between the structural design and the natural original canal cross section. For the economical purposes, the design always needs less width of the work, than the width of the bed of the original stream cross section, so a contraction may be needed where the work will be constructed; the literature indicated that, such a contraction must not be less than 0.6 of the original bed width. That contraction, of course, has a direct impact on the different hydraulic parameters, such as water depth, velocity, and flow regime in the location of the work. Changes of such hydraulic parameters may exceed their safe permissible values, and so the whole structure may face some dangerous situations, which must be overcome. In this paper, we present a technical survey of the previous research concerning canal width contraction, with the needed technical comments, and comparisons as a logical approach for a master-thesis under the same title.