Perspectives of Tilapia Lake in Al-Ain - Case Study Example

1.0 Introduction The Tilapia Lake is in Al –Ain which lies is in the eastern region of Abu Dhabi Emirate in the southern part of Dubai and the eastern part of Abu Dhabi. The eastern region has an area of about 13,100km2 Oman is located in the east while Dubai and Sharjah are in the north, Abu Dhabi is in the west while the Empty Quarter desert and Saudi Arabia is in the southern part. Togograplically Al-Ain is very unique and has variation as one travels towards the east. Jebel Hafeet is regarded as a monument in Al-Ain that is located to the south east and raising an elevation of 1300 meters (Brook, 2003). Sand dunes which with a vast variation in texture and tinged red due to iron oxide content can be found in North and East of Al-Ain. Al-Ain receive annual rainfall with a mean value of 96mm with the relative hu8midity being in the tune of 60% (United Arab Emirates University, 1993). The low level of humidity in Al-Ain more so during the summer period, has contributed a lot towards making it to be a popular destination for many holiday makers in this period of the year. UAE climate has been classified by Brook (2005) as being hyper arid with four distinct climate regions: the coastal zone that lies along Persian Gulf; the gavel plains dominating the Al-Ain area, the mountainous areas on the north eastern side of UAE and the central and Southern sand desert. There is more rainfall and lower temperature is recorded in the Northeast in comparison to the regions in the west. The average rainfall that was experienced from the period 1970 to 1992 in areas around Al Ain was 100-120mm. 2.0 Literature review 2.1 Groundwater Systems Groundwater systems are usually determined by the type of recharge processes, the geology of the rocks together with groundwater residence time and the processes involved in the discharge. The ground water quality in a region is largely determined by type of recharge processes and in the recent times they have been found to be influenced anthropogenic activities and their presence depending on the type of aquifer and the type of development in the neighborhood. The three types of flow characteristic are the local, intermediate and regional. The movement of ground water in UAE has been found to been from the East to West considering all the three types of flows, but for North and Liwa crescent, a groundwater high enables flows towards the South crossing the border to Saudi Arabia. It is approximated that the flow times from recharge zones in the East to the Sabkha discharge zones that lie in the Gulf coastlines may require 15,000 years (REM, 2004). With this type of slow groundwater movement there is considerably a high level of dissolution of salts in the groundwater and thus the high residence time translating to a high salt content; hyper-saline water which salt content beyond 200,00mg/l have been found on the Abu Dhabi coastline (ERWDA/FEA, 2005). 2.2 Types of aquifers Around 80% of the land in UAE is made of Quaternary sand and sand with gravel aquifers. The aquifers in the Eastern Region are mostly Quatanary sand together with gravels underneath which is very productive Upper Fars Formation that runs towards the east to neighboring Oman (REM, 2004). In the south eastern region is Lower Fars Formation, in Umm Az Zamoul area and limestone bedrock units. The discontinuous carbonates can be found within the hydrogeology in the north of Al Ain that is tectonically affected. The Quatenary sand aquifer which are underlain directly by the Lower Fars Formation is found in the Western region but in constrast to the case in the Eastern region, the Fars is a representation of a regional aquiclude. There is also thin coastal sabkha aquifers and the Baynunah formation , that comprise of Upper Miocene Sandstones continental and also conglomerates which have gypsiferous cap rocks are associated with formation of numerous low level lying mesas in the region. In both formations the aquifers are not fully developed with both being underlain by the regional lower fars unit aquiclude. 2.3 Unconsolidated Aquifers This are believed to the most common and most productive aquifers and they comprise and they include resent sand dunes and alluvial deposits at various age. In collective terms, the deposit are compost of surficial aquifers found in Abu Dhabi Emirates or may be compost of the shallow aquifer whose upper side is defined by the water table. The following units of the shallow aquifer have been mapped by the Groundwater Assessement project – GWAP: SAL refers to Quatenary aquifer/ aquitard units that is underlained direltly by the Lower Fars Formation this being a basal unit SAU compost both Quartenary sand and gravel aquifer that is underlain by the Upper Fars Formation as a basal unit. SAS represent the Coastal and inland sabkhas SAM represents Quarernary sand and gravel aquifer that is underlain tectonically emplaced dark Marlstones and shales being the major basal unit. SAJ is quaternary sand and gravel aquifer found in the east side of Jebel Hafit and is underlain by Upper Fars and Lower Fars Formations being the basal unit. Sabkhas are seen as being aquifers of no economic value as they contain ground water with hyper-salinity and brine in some of the locations. The hydrogeology and the hydrochemistry that is exhibited are captured by Wood and Sanford (2002) while their potential of being a brine resource has been developed by Czarnecki et al. (2000). The conclusion made by the former was that rainfall is the major supplier of water while the ascending terrestrial brine is seen as the dominant supplier of contained solutes in the coastal sabkhas that has a stretch of 300km long and 15km average width strip. 2.4 Groundwater Quality Ground water is seen to be the main source used in developing the land in all Arabian Gulf countries which Unites Arab Emirate (UAE) is part. It has been discovered in the resent past that the ground water exhibit a great variation in the UAE including the area the area where Tilapia lake is located. Some of the areas surrounding the lake have been found to have water with salinity level of over 1000mg/l in terms of total dissolved solids (JICA 1996, Murad 2007). Many factors are attributed to high ground water salinity, including the type of aquifer rocks, aridity and ground water recharge. Other factors are the thickness of the aquifer and due to water being over pumped and due to over consumption in the Abu Dhabi Emirate region of UAE (JICA 1996, Rathore et al. 2008). The tectonic activity that occurred in late cretaceous is believed to have brought about deformation displacements and thrusting in hard rocks in regions such as Oman and Hafeet mountains (Glennie et al. 1979). There are numerous studies that have been undertaken so as to find out what are the geological structures influence on groundwater accumulation as well as quality by use of remote sensing as well as geographical information system (GIS). With the abundance of remote sensing data , it has been possible for various techniques to find application through integrating a number of hydrological geomorphometric and geological parameters so as not only to define new ground water potential zones but also as away of solving other problems that are linked to groundwater quality (Prasad et al. 2007). Use of GIS has been done by Jaiswal et al. (2003) with the end product being the generation of ground water potential zones that can be used in developing rural areas. GIS technique has also been used by others like Krishnamurthy et al. (1996) and Obi Reddy et al. (2000), in their effort of defining ground water zones. GIS has also been applied by Srinivasa Rao and Jugran (2003) in the processing and in the interpretation of groundwater quality data. GIS is also seen as to be appropriate for multicriteria analysis when it comes to resource evaluation. In the UAE it was reported by Al Nuaimi (2003) and Murad et al. (2012) that there was an increase in salinity of the groundwater from east towards west as well north to south in Al Ain areas and also at foot of Oman and Hafeet Mountains which could be used as a pointer that there was a change in groundwater system in the previous decade. So as to be able to make a prediction and to identify the link between topographical attributes; and flow accumulation geomorphometric and groundwater salinity as well as for hydrological thematic maps and geological experts have used calculation from DEM and special correlation. The validation of the method involved comparison of hydrological data gathered from groundwater samples from groundwater wells (Murad etal. 2012). High salinity is highly associated with long residence time (Total Dissolved Solids-TDS). TDS is always linked groundwater quality and also may be a measure of distance from sources of recharge or the discharge area. TDS is usually found through analysis of waters whose sampling involves a variety of methods that are usually from boreholes or wells. It is advisable that a lot of caution should be taken when it comes to the interpretation of resultant TDS, whose calculation is analytical in nature owing to its relationship with electrical conductivity that is measured directly through field instrumentation. Other factors also may come into play, other than those that have already been mentioned and these may bring about over-bearing effect on salinity, with a good example being where gypsum or anhydrite layers may occur within a succession, which might be very thin but may have a huge effect on the increase of TDS of water samples in the well. There have been several classifications of types of groundwater which have been used internationally and different classifications have also been found to have association with different government agencies and different projects in different regions of UAE. The classification of groundwater quality which has been adopted in UAE are much more detailed in comparison to that of World Health Organization which is seen as being much more simplistic way of classifying drinking water with water with TDS of equal to or less than 1600mg/l being regarded as being fresh and TDS beyond this makes the water to fall into the brackish class. In the ABU Dhabi Emirate region of UAE the term fresh is regarded as being a local standard of measuring potable water. On the other hand electrical conductivity is usually used in the Agriculture Extension Department of Abu Dhabi Municipality & Agriculture classification where classification emphasis is on how suitable the water is for use in irrigation for some selected crops under some groundwater salinity which is pre-selected. The existence anthropogenic pollution of groundwater cannot be denied in many Emirates regions, the existence does not have any substantial effect on the region’s groundwater salinity. The local pollution which has been reported to have affected some of the surficial aquifers is linked to minerals like Nitrate and is associated with the use of organic fertilizers. 2.5 Salt lakes The saline lakes that have been studied are in high plains of the western southern Great Plains in USA. The region is predominated by the saline lake and playa wetlands which are the predominant hydrological surface features. This is particularly seen in Southern High Plains (SHP) in eastern New Mexico and northwest Texas. A lot of effort has been directed in the conservation and management of playas, this being fueled by concerns of natural and anthropogenic threats to their functional ecology and structure (Smith 2003; Johnson et al. 2012). Over 20,000 playas are described as being shallow that originate from precipitation that recharges wetlands. They have are been described as islands with biological diversity in one of the area in North America that is highly agriculturalized (Johnson et al. 2012). Unlike the case of playas saline lakes of SHP have not drawn much attention with regards to conservation. Even though more attention is directed towards playas, saline lakes are most jeopardized wetland ecosystem in the regions of their existence and are identified as a high priority community (Texas Parks and Wildlife Department, 2005). In North America it is approximated that only 1 saline lake exists in every 500 historical playas (Smith 2003), but there being rare only makes them together with their biota results into their being more susceptible to both natural and anthropogenic destruction. Saline lakes are different from plays in ecological sense, in geological sense and hydrologically (Hall, 2001). Saline lakes cover larger areas as compared to playas; their water chemistry is saline with TDS of more that 200g/L (Dockery, 1989). The saline lakes will always be found to be underlain by deep Permian salt dissolution areas and dunes are found to border their leeward side from deflation. Saline lakes are found to be older than playas by 3000,000 ybp and most saline lakes in North America region have indication of human occupation. Human settlement could be attributed to existence of one or more freshwater spring that could have been connected to Ogallala aquifer within an environment that lacked surface water. Saline lakes are still being counted as being discharge wetlands, and presently they receive big portion of surface water by direct precipitation as well as overland flow, as natural artesian freshwater springs that may have been linked to the lakes ceased flowing over 50 years ago (Brune 1981). Some evidence also have shown that the groundwater elevation in saline lakes lower by at least 7 to 8m in comparison to what it was 25000-55000 ybp (Wood 2002). Conservation efforts of saline lakes take a multifaceted approach but stopping of spring flow results into reduced residence time of surface water and increased salt concentration. The hydrology of saline lakes is affected by the interaction among anthropogenic disturbances, variable hydroperiods, precipitation patterns that are unpredictable and high evapotranspiration (Saalfeld et al.,2012). A good example is where there is coincidence of the yearly irrigation practices with groundwater pumping, period of long draughts and surface water evaporation thus making water to be temporal. According to Mathews (2008) the ability to predict the increase in rates of evaporation in future climate change will result into a further reduction in hydroperiods in saline lakes, where the saline lakes are at high risk of alteration due to the present day climate change. Rooted vascular plants associated with saline lakes typically will be close to remaining artesian spring discharge zones thus the basins floor are with no vegetation. Saline lakes being in very hostile environment will only have a small fraction of flora that is in playas (Haukos & Smith 2004) and will only be inhabited by fauna that are highly adapted to the saline environment (Iverson et al. 1985, Saalfeld et al. 2012). 3.0 Methods applicable in groundwater investigation Accumulation of groundwater and salinity is linked to flow accumulation, geological fractures, irrigation areas, topographic slope, aspect and relief of the area. In order for groundwater salinity and groundwater accumulation identification and prediction to be possible there is need for preparation of various thematic maps. In a region neighboring the lake seven different thematic maps were included as important factors for integration in GIS environment which served as input layers in predicting groundwater salinity. The factors that need to be put into consideration include: (i) geological fractures which bring about increased carbonate rocks dissolution due to its service as a channel (ii)drainage network that has connection with geological structures and thus brings about increased chemical dissolution as well as development of karst features (iii)relief which is a reflection of high incidences of geological fractures intersecting, soil salinity as well as control flow accumulation, (iv) aspect which is associated with controlling of flow direction and accumulation (v) slope takes care of the speed at which the ground water moves and the erosion of carbonate rocks through mechanical means (vi) irrigation area that is responsible for the increase in rate of evapotransipiration. In the region of study there was extraction of geological fractures which were then mapped from enhanced thematic maps of terrain parameters through application of non linear Soble filter whose threshold is 10% (Scott 2005). The maps to be used are to include aspect, shaded relief and slope in all the direction (0°,45°,90°,135°…360°). The geological fractures can be readily be mapped in areas where there is a contrast with landscape in the neighborhood depending on the landscape and /or change of tone. Drainage basins and drainage network extraction is through DEM through D8 algorithm (Jenson and Dominque 1988) which can be implemented in Arc version 9.2 software. The flow directions can be identified automatically by use of drainage downhill vectors algorithm that is implemented in IIwise v.3.7 software. The calculation of topographic slope, relief and curvature calculation is done by DEM by use of ArcGIS v 9.2 software. Then there can be comparison of calculated maps with the geological map (Woodward and Al Sharhan 1994) and the hydrological data (electruical conductivity and salinity) which are sampled from wells (Murad et al., 2012), are used in identifying the spatial distribution electrical conductivity and groundwater salinity in study area (Khalifa 1997, Murad et al. 2010). 4.0 Research findings 4.1 Topographic attributes control flow accumulation in Al Ain Mapping of geographical structure in Al Ain in Hafeet Mountain and the neighboring areas is an alternative to groundwater prospecting in such an area that is highly fractured carbonate terrains. The use of remote sensing data is able to give a means regarded as being effective for use in the characterization of the fracture systems in the areas on large scale. The southwestern part of Al Ain the pattern of geological fracture are mostly northwestern-southeastern and north northeast and laying parallel to the fold axis of Hafeet Mountain (Woodward and Al Sharhan 1994). The faulted blocks in the area plummet from Zakher and Neima in the North in the direction of Ain Al Fayda (south) and the east side at Mubazzah towards Neima and Ain Al Fayda which lies in the southeast where the difference in elevation is 30m for the former case and 100m for the later. The direction of flow, direction of slope, flow accumulation, the gradient of slope, the thickness and relief of shallow alluvial aquifer and thus the level of groundwater is being controlled by the two set of geological fractures. The findings are also in agreement by other results from previous borehole records and geophysical survey (Mural et al. 2010,). The flow accumulation zones, existence of abnormally high discharge of springs and the rising of groundwater level are closely linked to highly fractured that controls upward transport deep groundwater (Lukin 1987, Murad et al. 2012). Geological fractures are associated with discolosed zones in the subsurface faulted folding blocks as can clearly be witnessed in boreholes as well as in topographical profiles (Murad el al. 2012). The features play important role in the dissolution of carbonate rock and in increasing concentration of anions and cations in the groundwater which is manifested by high presence sulphate and bicarbonate (Murad et al. 2012). In the Ain Al Fayda and Mubazzara the intersection of geological fracture that shows a low-land like depression shape which exhibit different values in terms topographic attributes and controls flow accumulation and is also the recipient of the biggest share of rainwater as well as groundwater through gravity (Murad el al., 2012). In Mubazzara area the occurrence of groundwater recharge is mainly in areas with rock outcrops through geological fracture interactions while for the case of Ain Al Fayda lateral flow and upward transport in deep groundwater is experienced. The topographic relief in Ain Al Fayda and Neima are have been found to have low values of les than 7m while a moderate value of 70m have been registered in Mubazzara area. This relief is responsible for landsurface water flow from the eastern area of Mubazzara towards southwest towards Ain Al Fayda and from near Neima in North to Ain Al Fayda in Ssoutheast. Due to wide areas on which irrigation is being practiced and presence of springs in Ain AL Fayda and in Mubazzara is a strong indication of presence of lateral and upward transport of deep groundwater to ground through geological fractures intersections (Murad elal. 2012). Topographic slope found in Hafeet Mountain have been classified as ranging from moderate to steep slope. About 85% of the area which was studied around Hafeet Mountain was classified as being gentle sloped indication that in this area groundwater would decelerate and this lead to increased infiltration and accumulation of salts (Subba 2006). The area on Hafeet Mountain is characterized with high volumes of surface runoff with water being dissipated mostly which in turn brings down water infiltration. A view of aspect map and aspect distribution from a slope diagram in Hafeet Mountain and surrounding reveal that common slope directions and consequently accumulation and flow direction are located in the E, SW and WSW which partly is dependant on fault intersections and displacements. 4.2 Correlation analysis between topographic attribute and groundwater salinity In Al Ain region the existence of a very strong spatial variation in topographic attributes and groundwater salinity and irrigation area associations has been observed during analysis at each point and site. There has been overwhelming evidence from spatial correlations and analysis groundwater salinity are a reflection of the chemical composition of the host rocks, topographic relief, the flow length, aspect and gradient of slope. The findings concurred with other findings from hydrogeolochemical analysis of water samples collected from water wells (Murad et al. 2012). Ground water which has a high levels of Ca2+ , Mg2+, , SO42- and HCO32- is an indication of anions and cations that originate from dissolution of dolomite, limestone and gypsum. On the other hand high level presence Na+ NO3 and Cl- is a reflection presence of rock salt and intensive irrigation practice and general agriculture area presence. High concentration of K+ in groundwater is an indicator of cations that results from dissolution of igneous rock (Mathess 1982). If a long distance separates the downstream and upstream, these might bring about high salinization in the aquifer and groundwater through the leaching in the downstream end, thus leading to a symmetrical relationship between groundwater salinization and stream length (Murad et al. 2012). The ground water of an area like Ain Al Fayda would be expected to exhibit high levels of cations and anions unlike Mubazarha groundwater. Low topography, low slope and low relief results into decreased water flow and the decreased flow is likely result into a silinized groundwater aquifer (Tkachuk, 1970). It is on this ground that water salinity in Ain Al Fayda is found to be much higher in comparison to the case of Neima area and Mubazzar. This is a result that manifests that flow accumulation zones and consequently groundwater salinization are always related to fault intersections (Florinsky 2000). Spatial correlations in these areas have also indicated that groundwater salinity is dependant evapotranspiration, flow direction and intensity of irrigation. Areas with level of irrigation practice and agricultural areas like in the case of Al Ain Fayda and Mubazzar are expected to exhibit high levels of sodium, chlorine and bromine in their groundwater (Murad et al. 2012). The groundwater test results for Ain Al Fayda and Mubazzara has shown the former of having high salinity level in comparison to the later. This scenario is attributed to Ain Al Fayda having relief of low slope percent and low topography, thus receiving lateral and upward transport of both mixed and deep-seated through fractured zones. It is seen generally that the level of anion and cations in groundwater wll increase north towards the south and from east to southwest (Khalifa 1997, Khalifa, 2003). This scenario makes he groundwater in Ain Al Fayda to have the highest level of cations such as Ca2+, Na+, Mg2+ and K+ and anions such as HCO32- SO42-and Cl-. A strong correlation is also observed between physical properties such as electrical conductivity and groundwater temperature and also between geological fracture intersections and topographic attributes (Murad et al. 2012). High temperature of groundwater samples collected indicated that there was an increase from Ain Al Fayda in the direction of Mubazzara. This is attributable to Mubazzara area being located in rocks that are deeply and highly fractured that act as passways for upward transport (Kerrich 1986). By use of spatial correlation between geological lineament displacement and geographical attributes and interactions is able to give a clearer understanding with regards spatial distribution in groundwater accumulation and groundwater salinity (Florinsky, 2000). This is brought about by topographical attributes taking into consideration the slope gradient as well as direction of the slope (Gessler et al. 1995). Verification results have shown that applying topographic aspects and remote sensing in the prediction and identification of spatial distribution of the groundwater accumulation and salinity cost effective in comparison to other traditional methods that involve field investigation and geophysical survey more for the cases involving arid and desert regions. The correlations finding are useful as basic hydrological information which is helpful in assisting in hydrological setting and managing land use. 4.3 Findings on Tilapia Lake The lake is also known as Quad lake, Al Qusais, Zakher pools and sand dunes from various quarters. The lake is reported to have been in existence come in existence in 2004. The origin of the lake has not been clear to many with some attributing it to a rise in groundwater, some think it is a natural spring still others associating it with runoff from the neighboring wastewater treatment plant. The year 2004 witnessed Al Ain Municipality overwhelmed in dealing with excess water. In some areas the ground water was reported to have risen to a level of 0.5m below the surface, thus leading to appearance of water in cellers which was a threat to foundations and all other concrete infrastructures in Al Ain. The rise in water also led to the disruption of as there was need of drying out excavations. The reasons given for the rise in water levels in the year 2004 included a new desalination line from Fujairah. The sewage plant in Al Ain was reported to have been 30 years earlier and in at least 10 years it had been over capacity up to three times. Due to lack of sufficient infrastructure of pumping where it was required, treated sewage water was being dumped by the authorities in Wadi Al Ain as during the winter there was excess capacity that could not be sustained by the pipes. The authorities chose to shift the excess water 29 kilometers downtown of Al Ain in the south and this is believed to have contributed to the coming up of the lake. Use of the water in the lake for irrigation purposed for irrigation purpose made the lake to al most disappear in 2008 but a heavy rain of 120mm in a signle day made the lake to receive a lot of water making it to swell in excess of 1.2million square metres with a depth of 20metres in deepest areas. The water levels in some areas of Al Ain went up such that it could reach the storm sewer thus making the new lake to receive water constantly. A part from the lake receiving stormwater which was its initial purpose it was also reported that the lake was being used as disposing products originating drying activities undertaken by Abu Dhabi Sewerage Service Company with water being pumped from worksites into rainwater drainage system and thus getting into the lake. On the other hand salinity test carried out on the lake water indicated that the origin of the water is likely to groundwater and not treated water was traceable in the tests. Some of the town authorities were reported to have contradicted the salination tests finding indicating that the salinity could be attributed to stoppage of pumping sewer water into the lakes and the dumping of foreign objects into the lake. Another report that indicated that the salination level was reducing indicated that even when water was no longer being pumped into the lake and with no precipitation gives strength to the argument that groundwater was contributing to the existence of the lake. Tilapia lake has been attraction to many wildlife. Up to 200 different species of birds including migrating ducks and herons which are rare to be found in a dessert environment have stopped at the lake for arrest or for breeding. The lake is also a home to tilapia (the origin of the name that has been given to the lake). The fish is believed to have been introduced to the lakes by the birds which may have hooked the eggs that lie in the shallow edges of lakes in their feet and transferred them to the lake. While the lake is seen to be the delight of nature to one ecological entomologist the lake is regarded as an ecological disaster as it has compromised the natural habitat. 5.0 Conclusion From the study it has been that spatial correlation and GIS can be used in successfully predicting groundwater salinity and groundwater potential. From the spatial correlation which has been done in areas surrounding the lake it has been seen that groundwater salinity and groundwater accumulation are determined by direction of flow, the slope, the distance between upstream and downstream, the catchment area, irrigation areas as well as composition of the host rock. Sites that qualify to be classified as being of low topography, low slope 5 and low relief will be found in carbonate rocks which are highly fractured and are found to correlate with sites of high groundwater potential and groundwater salinity. From the issues raised about Tilapia Lake it the possibility of the water in the lake being contributed by groundwater is high. References Al Nuaimi H. S. (2003), Hydrogeological and Geophysical Studies on Al Jaww plain, Al Ain Area, United Arab Emirates,” M.Sc Thesis, United Arab Emirates University, Al Ain, 2003, 159p. Brook, M.C, (2005) Development of a Groundwater Monitoring Network for Abu Dhabi Emirate Brook, M.C 2003, History & Current Status of Municipal Wellfields in the Eastern Region of Abu Dhabi Emirate, 1979-2002. Vol I & 11 Brune, G.M. 1981. Springs of Texas: Volume 1. Branch-Smith Inc., Fort Worth, Texas. Dockery, R.M. 1989. Origin of Shafter, Whalen and Lazy X Ranch lake basins, Andrews County, Texas. MS Thesis. Texas Tech University, Lubbock. ERWDA/FEA 2005 Assessment of residual Pesticide and Fertiliser Residues in groundwater in Abu Dhabi Emirate. Final Report Fitterman, D.V.,et al (1991). Electromagnetic mapping of buried paleochannels in eastern Abu Dhabi Emirate, U.A.E.: Geoexploration, v. 27, p.111-133, Elsevier Science Publishers B.V., Amsterdam. Glennie, K.W., et al (1974), Geology of the Oman Mountains, Verhandelingen van het oninklijk Nederlands geologisch mijnbouwkundig Genootschap. The Royal Dutch Geological and Mining Society (KNGMG), Parts 1 and 2, , p. 423. Hall, S.A. 2001. Geochronology and paleoenvironments of the glacial-age Tahoka formation, Texas and New Mexico High Plains. New Mexico Geology 2001:71–77. Haukos, D.A. and L.M. Smith. 2004. Plant communities of playa wetlands in the Southern Great Plains. Spec. Publ. Mus. Texas Tech Univ. No. 47. Iverson, G.C., P.A. Vohs, and T.C. Tacha. 1985. Habitat use by sandhill cranes wintering in western Texas. J. Wildlife Managem.49:1074–1083. Jaiswal, R.K., et al (2003), Role of remote sensing and GIS techniques for generation of groundwater prospect zones towards rural development-an approach. International Journal of Remote Sensing, 24:993–1008 Jenson, S.K., and Domingue, J.O. (1988), Extracting Topographic Structure from Digital Elevation Data for Geographic Information System Analysis. Photogrammetric Engineering and Remote Sensing,Vol. 54, No. 11, November 1988, pp. 1593–1600. JICA, (Japanese International Cooperation Agency) (1996), The master plan study on the groundwater resources development for agriculture in the vicinity of Al Dhaid in the UAE, JICA International Cooperation Agency,(1996), Final Report. Johnson, L.A., D.A. Haukos, L.M. Smith, and S.T. McMurry. 2012. Loss and modification of Southern Great Plains playas. J. Environm. Managem. 112:275–283. Krishnamurthy, J.N., et al (1996). An approach to demarcate ground water potential zones through remote sensing and geographical information system. Int J Remote Sens 17:1867–1884 Lukin, A.A. (1987), Experience in Development of Morphostructural and Hydrological Analysis Technique. Nauka, Novosibirsk 111 pp., in Russian. Matthews, J.J. 2008. Anthropogenic climate change in the Playa Lakes Joint Venture region: understanding impacts,discerning trends, and developing responses. Report to the Playa Lakes Joint Venture. Mathess, G. (1982). The Properties of Groundwater” John Wiley and Sons, New York, 1982, pp. 215-255. Murad A.A., et al (2007), Comprehensive Assessment of Water Resources in the United Arab Emirates (UAE) Water Resour Manage (2007) 21:1449–1463 DOI 10.1007/s11269-006-9093-4 Obi, R.P., et al(2000), Evaluation of groundwater potential zones using remote sensing data- a case study of Gaimukh watershed, Bhandara di Resources en Eaux Minerales (REM) 2004. Qualitative valuation of mineral water resources in the area of Al Ain, UAE. Rathorea, V.S., et al (2008), Influence of neotectonic activity on groundwater salinity and playa development in the Mendha river catchment, western India. International Journal of Remote Sensing Vol. 29, No. 13, 10 July 2008, 3975–3986 Saalfeld, S.T.et al. 2012. Snowy plover nest site selection, spatial patterning, and temperatures in the Southern High Plains of Texas. J. Wildlife Management. 76:1703–1711. Smith, L.M. 2003. Playas of the Great Plains. University of Texas Press, Austin. Texas Parks and Wildlife Department (TPWD). 2005. Texas Comprehensive Wildlife Conservation Strategy 2005–2010. Texas Parks and Wildlife Department, Austin. Srinivasa, R.Y., Jugran, K.D. (2003). Delineation of groundwater potential zones and zones of groundwater quality suitable for domestic purposes using remote sensing and GIS. Hydrogeol Science Journal 48:821–833 Subba R.N. (2006), Groundwater potential index in a crystalline terrain using remote sensing data. Environ Geol Tkachuk, V.G. (Ed.), 1970. Hydrogeology of the USSR, vol. 8. The Crimea. Nedra, Moscow 364 pp., in Russian. UAE University 1993. Atlas for United Arab Emirates. Wood, W.W. 2002. Role of ground water in geomorphology, geology, and paleoclimate of the Southern High Plains,USA. Ground Water 40:438–447. Woodward, G.L. and Al Sharhan, A.S. (1994) Domlomitization and Chertification of the early Eocene Rus Formation in Abu Dhabi, UAE Sedimentary Geology, (91), p. 273-285. Appendix 1 Tilapia lake Distichlis spicata meadow, Tahoka Lake Appendix 2 SHP showing largely un-vegetated basin floor (Tahoka Lake) Submerged bed of Ruppia maritima, White Lake Read More

With this type of slow groundwater movement there is considerably a high level of dissolution of salts in the groundwater and thus the high residence time translating to a high salt content; hyper-saline water which salt content beyond 200,00mg/l have been found on the Abu Dhabi coastline (ERWDA/FEA, 2005). 2.2 Types of aquifers Around 80% of the land in UAE is made of Quaternary sand and sand with gravel aquifers. The aquifers in the Eastern Region are mostly Quatanary sand together with gravels underneath which is very productive Upper Fars Formation that runs towards the east to neighboring Oman (REM, 2004).

In the south eastern region is Lower Fars Formation, in Umm Az Zamoul area and limestone bedrock units. The discontinuous carbonates can be found within the hydrogeology in the north of Al Ain that is tectonically affected. The Quatenary sand aquifer which are underlain directly by the Lower Fars Formation is found in the Western region but in constrast to the case in the Eastern region, the Fars is a representation of a regional aquiclude. There is also thin coastal sabkha aquifers and the Baynunah formation , that comprise of Upper Miocene Sandstones continental and also conglomerates which have gypsiferous cap rocks are associated with formation of numerous low level lying mesas in the region.

In both formations the aquifers are not fully developed with both being underlain by the regional lower fars unit aquiclude. 2.3 Unconsolidated Aquifers This are believed to the most common and most productive aquifers and they comprise and they include resent sand dunes and alluvial deposits at various age. In collective terms, the deposit are compost of surficial aquifers found in Abu Dhabi Emirates or may be compost of the shallow aquifer whose upper side is defined by the water table. The following units of the shallow aquifer have been mapped by the Groundwater Assessement project – GWAP: SAL refers to Quatenary aquifer/ aquitard units that is underlained direltly by the Lower Fars Formation this being a basal unit SAU compost both Quartenary sand and gravel aquifer that is underlain by the Upper Fars Formation as a basal unit.

SAS represent the Coastal and inland sabkhas SAM represents Quarernary sand and gravel aquifer that is underlain tectonically emplaced dark Marlstones and shales being the major basal unit. SAJ is quaternary sand and gravel aquifer found in the east side of Jebel Hafit and is underlain by Upper Fars and Lower Fars Formations being the basal unit. Sabkhas are seen as being aquifers of no economic value as they contain ground water with hyper-salinity and brine in some of the locations. The hydrogeology and the hydrochemistry that is exhibited are captured by Wood and Sanford (2002) while their potential of being a brine resource has been developed by Czarnecki et al. (2000). The conclusion made by the former was that rainfall is the major supplier of water while the ascending terrestrial brine is seen as the dominant supplier of contained solutes in the coastal sabkhas that has a stretch of 300km long and 15km average width strip. 2.4 Groundwater Quality Ground water is seen to be the main source used in developing the land in all Arabian Gulf countries which Unites Arab Emirate (UAE) is part.

It has been discovered in the resent past that the ground water exhibit a great variation in the UAE including the area the area where Tilapia lake is located. Some of the areas surrounding the lake have been found to have water with salinity level of over 1000mg/l in terms of total dissolved solids (JICA 1996, Murad 2007). Many factors are attributed to high ground water salinity, including the type of aquifer rocks, aridity and ground water recharge. Other factors are the thickness of the aquifer and due to water being over pumped and due to over consumption in the Abu Dhabi Emirate region of UAE (JICA 1996, Rathore et al. 2008). The tectonic activity that occurred in late cretaceous is believed to have brought about deformation displacements and thrusting in hard rocks in regions such as Oman and Hafeet mountains (Glennie et al. 1979).

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