الفهرس 
IntroductionOnly 14 pages are availabe for public view
Abstract
The city of Kufra is located at the southeastern part of Libya, between latitudes 24°11”N and longitudes 23°17ˊE. An arid desert region, where groundwater is the main and only source in the region, and there is no other source of water.
The city of Kufra was chosen for this study, due to the importance of groundwater in the region. The lack of sanitation networks and wastewater treatment plants, and the reliance on wastewater disposal in space and near residential neighborhoods and drinking water wells, and the lack of hydrological and environmental studies in general.
The study relies on comparing the results of the analysis of samples of drinking water wells in the study area, with the specifications of the World Health Organization and the Libyan standard specifications.
Seventeen groundwater samples were collected from the Drinking water wells in the city of Kufra. The collected samples were subjected to different analyses, in order to conduct hydro-chemical and bacteriological studies of the study area. The available groundwater water resources quality is assessed, their suitability for different uses are defined, especially the drinking water.
The work was carried out by locating each well by GPS, coding and measuring water levels, and measurements for all wells. Samples were taken in different periods in three stages, the first in March, the second in June and the third in November of 2016.
The physico-chemical parameters of the studied groundwater samples revealed that the groundwater of Kufra city are suitable, where the pH ranges from 6.1 to 7.04. The recorded temperatures of the studied groundwater of Kufra city samples are fluctuated from 25 to 30°C.
The total dissolved salts (TDS) range from 160 to 1936 mg/L. Most of the studied groundwater samples have electrical conductivity (EC) values ranging from 250 to 3025 μS/cm.
from the previous discussion, the physical and chemical parameters of the studied groundwater samples showed that, the groundwater of the city of Kufra is basically acidic to neutral, and the brackish nature to the water is basically fresh and conforms to the specifications except in well No. (14), in which the dissolved salts percentage exceeded the standard specifications of the World Health Organization and the Libyan.
The analysis of positive ions (sodium, potassium, calcium and magnesium) shows that, some wells have high percentages of these parameters above the permissible ratios, according to the WHO standards and the Libyan standard specifications. While analyzing the negative ions (chlorine, sulphates, bicarbonate and nitrates) showed exceeding the permissible percentages in some wells.
The bacterial tests in the study area indicate that, the fecal coliform bacteria per 100 ml/L is confined between 1 and 4 colony, forming units per 100 ml.
Hydrochemistry results in the study area showed that, 23.5% of water is strong chloride, while 64.70% is average chloride and 11.76% is low chloride. It was classified as 100% carbonate water and 47% high sulfate water and 41% sulfate water.
The groundwater in the Kufra basin was evaluated for various uses, including irrigation, and classified in terms of important properties, such as electrical conductivity (EC), total dissolved salts (TDS), residual sodium percentage (RSC) and magnesium adsorption rate (MAR).
For electrical conductivity, according to the Fipps classification (2003), samples are good at 70.588%, 23.529% is permitted, and 5.882% disallowed.
As for the total dissolved salts (TDS), according to Fipps classification (2003), they are excellent at 5.88%, good at 70.58%, medium at 17.64%, and bad at 5.88%.
As for the soluble sodium SSP, with Eaton classification (1950), 82.352% is safe water and 17.647% is unsafe water, and for SAR adsorption, according to Todd classification (1980), the water is 100% excellent, and the residual sodium carbonate (RSC), according to Todd classification (1980), 100% is excellent water.
For magnesium adsorption (MAR), according to Todd’s (1980) classification, most samples fall below 50 mg / L at 82.35% and greater than 50 mg/L at 17.65%.
As for the chlorine content, despite its importance in the permissible rate, increasing the percentage leads to toxicity for plants and burning leaves. In general, water in which chlorine is less than 140 mg / liter is considered of good quality irrigation water, and most of the groundwater samples in the Kufra basin are below this percentage.
The evaluation of groundwater in the Kufra basin is good for irrigation. As for the evaluation of groundwater for domestic use, the results of dissolved salts, corrosion and total hardness, the total dissolved salts, according to the classification of Provold and Daniel are 5.88% excellent water, 70.58% good water, 17.64% medium water and 5.886% acceptable water .
The average total hardness (TH) and hardness of this water, according to the classification of Sawyer and McCarthy, (1967), water is safe by 11.764%, medium hard water by 29.44%, 23.52% by hard water, and by 29.411. Very hard water.
As for the percentage of erosion (CR), according to the classification of Ryznre, (1944), the ratio is 5.88% and 117.94% is unsafe water. The nitrate pollution index (NPI) indicates that, the water is free from pollution. Likewise, the water quality index shows that, 47.06% is excellent water, 41.18% is good water and 11.76% is poor water.
The samples of the bacterial analysis were classified, according to the specifications of the World Health Organization. 76.470% is safe water and 23.53% is unsafe water.
Recommendations
1- Putting a permanent monitoring program, to observe the groundwater quality and to determine the annual and seasonal changes, in order to put a proper strategy to protect and remediate the aquifer, especially that the groundwater is the lonely water resource in Kufra area.
2- Control actions of private water well drilling companies, by the related authority, to limitation the random and unscientific wells drilling.
3- Establishing a modern database, that includes wells depths, productivity, date of drilling and geological information for seepages, that benefit studies and aid in the operation and maintenance process.
4- Accelerating the establishment and setting up of sewage networks and sewage treatment plants and not continuing to dispose the wastewater in the space without treatment.
5- Maintaining the cleanliness and protection of the areas surrounding drinking water wells.
6- Conducting more research and studies, to ascertain the validity of drinking well water and defining the extent of the influence of sewage water swamps, near the wells locations.