The aquifer in the study area is mostly covered with Indogangetic alluvium and is somehow deep. They are tapped mostly by private devices such as tube wells, pump sets rahats and the rest which are found mostly in the rural areas for their domestics used as well as for irrigation purposes. Some places have shallow aquifer ranges from 20 to 30 meters, which easy to dig for private purposes. But, for the state were dogs up to 100 to 130 meters. The groundwater fluctuation varies from place to place, usually 0.2 to 0.8 meters between the pre-monsoon to post-monsoon season.
In view of the possibility of Malaysia having operational nuclear power plant (NPP) by the year 2030 (Saleh et al., 2014a), measurement and monitoring of terrestrial gamma radiation dose as well as the determination of the primordial radionuclides levels in soil and water are great important in NPP site assessment. This will enable areas of needs be identified and steps be taken to fulfill the International Atomic Energy Agency (IAEA) and Atomic Energy Licensing Board (AELB) of Malaysia requirements for environmental radiological data for nuclear power plant. Despite the great interest shown in measuring environmental radioactivity in Malaysia, literature have shown that the states of Kelantan and Terengganu were not fully covered (Alias et al., 2008; Hamzah et al., 2008; Hamzah et al., 2012; Hamzah et al., 2011a; Hamzah et al., 2011b; Hamzah et al., 2011c).
The amount of water that will ultimately arrive at the water table is defined as natural ground water recharge. The amount of this recharge depends upon the rate and duration of rainfall, the subsequent conditions at the upper boundary, the antecedent soil moisture conditions, the water table depth and the soil type. Recharge is taking place in little and significant quantity for spatially and temporally is subjective by parameters such as meteorology, soil characteristics, earth surface cover, slope and deepness of groundwater level [3,4,5]. The assessment of groundwater
ABSTRACT: Water is indispensable to all life on earth. However, fresh water is constantly formed newly through a phenomenon known as hydrological cycle. Ground water recharge is the process by which water percolates down the soil and reaches the water table. Estimation of groundwaterrecharge from precipitation is vital for water resources assessment and planning. It is particularly important in regions like Puducherry where there is large demand for ground water supplies. Where such resources are the key to economic development. Recharge is a fundamental component of groundwater systems, and in groundwater-modeling exercises recharge is either measured and specified or estimated during model calibration. The most appropriate way to represent recharge in a groundwater model depends upon physical factors, availability of data and study objectives. In this paper soil water balance technique was used, which we define here as the quantity of water that flows into the aquifer after the natural losses like evapotranspiration, runoff and soil moisture content. For calculating the average monthly evapotranspiration and runoff, we adopted Food and Agricultural Organization Penman-Monteith (FAO56 – PM) equation and SCS runoff curve number.
Variations in radon concentration have generally been observed in connection with seasons. Radon concentrations in groundwater of the same well vary between wet and dry seasons (Figure 3). Generally, radon concentrations were slightly high in the dry season and low in the wet season. The low radon concentrations would be expected in the wet season due to the effects of dilution in a large volume of water as a result of recharge from nearby river or infiltration from rain water. However, wells B9, B17, D4, and D8 showed the opposite results (i.e. high radon concentrations in the wet season and low in the dry season). This was probably due to infiltration of rain water containing high dissolved radon as a result of the dissolution of soil gas during movement through the unsaturated zone.
Namibia, located in an arid climate is becoming more dependent on groundwater, especially during droughts. The quality of the groundwater obtained from different ground- water basins are highly variable. In general, groundwater conditions are unfavourable due to limited availability, little and unreliable recharge, low borehole yields, poor ground- water quality and high risks of contamination (Christelis and Struckmeier, 2011). It is therefore important to as- sess groundwater in order to understand the factors that cause variability in the quality. In this study, we use en- vironmental tracers to assess the nature of recharge and control of the quality of groundwater in the Kuiseb Basin and Cuvelai-Etosha Basin. Potential evapotranspiration in the Kuiseb Basin (785–1241 mm yr −1 ) and Cuvelai-Etosha Basin (1880–2173 mm yr −1 ) are variable (Kaseke et al., 2016). On an annual basis, the rainfall frequencies and inten- sity vary significantly in the Kuiseb Basin (8–255 mm yr −1 ) and Cuvelai-Etosha Basin (410–690 mm yr −1 ) (e.g., Kaseke et al., 2016), which determines how rain is affected prior to recharge of groundwater. In the Kuiseb Basin, there is lim- ited surface ponding and runoff and the basin is predom- inantly dry. In contrast, the Cuvelai-Etosha Basin is prone to alternating floods and droughts and water ponds periodi- cally on the surface and there is intermittent river flow during flood periods. In the Kuiseb Basin, the quality of groundwa- ter although portable is highly variable across the basin while in the Cuvelai-Etosha Basin, groundwater quality is mostly poor due to high salinity (Falke, 2008).
The UAE with Saudi Arabia and Kuwait is considered one of the largest users of desalinated water in the region, and these three countries are accounting for 77% of the total of the region . The desalination technology started in UAE in 1976, when the first plant was estab- lished in Abu Dhabi with a capacity of 66000 gal- lons/day. The establishment of desalination plant since that time indicates that the water scarcity is an old prob- lem and the severity of this problem is increasing annu- ally. Over the time, the water demand for domestic, ag- ricultural and industrial is increasing, so new desalina- tion plants are being constructed in the country . A total of 36 desalination plants were built in UAE by the end of 2006. Beside this, there were 10 main desalination stations belonging to FEWA and operating in the north- ern and eastern parts of the country . Also, there were 8, 5 and 12 main desalination stations in Abu Dhabi, Dubai and Sharjah, respectively [13–16]. In addition, there were 2 plants to desalinate groundwater in Umm Al Quwain .
Artificial recharge is another alternative as a valuable water management tools that effectively help to offset increased demands for water . Availability, quality and quantity of source water available, resulting water quality (reactions with native water and aquifer materi- als), clogging potential, underground storage space available, depth to underground storage space, transmis- sion characteristics, and costs are some factors control- ling the feasibility of artificial recharge method . The lithological studies in the study area reveals that the northern parts especially in Chitgar and the region be- tween Saeid Abad, Ghale Hasan Khan and Shariar can be considered as suitable recharging zones due to thick and
Protection of groundwater resources is essential from a strategic point of view. During the long drought that hit the country during the 1980s, groundwater use was the only recourse that allowed farmers to maintain the viability of their farms and thus avoid abandoned fields and the acceleration of the rural exodus. However, these withdrawals reached unsustainable levels, exceeding the volumes of annual recharge and drawing on the stock of non-renewable water.
Over the last few years, a steady rise in groundwater levels has been observed in several parts of Aswan City. This reflect environmental problems existing in many areas of the city, where it creates swamps and ponds and affects the basement of many buildings as it is shown in El-Seil, KhorAwada, Phatemic graves, El-Aqad build- ings, Blood Bank, Military building, El Shallal and KIMA factory area (Figure 1 and Figure 2). Rising groundwa- ter levels are expected to be a chronic problem and will likely be a major issue for residential areas of Aswan city.
The methodology presented can be useful to quantify the origin of recharge in urban areas. However, the transfer from mixing ratios to recharge ratios is not straight forwards. In general, a flow model will be required to properly account for spatial and temporal variations. A preliminary analysis (assuming the measured wells are representative of the be- havior of the full aquifer) suggests that 22% of total recharge comes from the water supply network, 30% from wastewa- ter, 17% from Rainfall recharge in northern non urban area, 11% from Bes`os River, 20% from runoff infiltration, while seawater intrusion contribution is almost negligible. This has consequences in both the evaluation of groundwater bal- ances and in identifying the potential quality of groundwa- ter based upon the quality of water in the end-members (or recharge sources). This has important potential implications in groundwater management in urban areas.
Effect of water head on recharge rate is analyzed in the case of clear water, water containing different concentration of clay and algae and water containing mixture of both clay and algae. laboratory experiments are conducted to find out the relationship between recharge rate and water head over the filter. Experiment results are discussed below.
The NCP is located in the eastern part of China, has a total area of about 140 000 km 2 . This region comprises the plain area of Beijing, Tianjin and Hebei Province and the plain area of Henan and Shandong provinces to the north of the Yellow River, which is a typical plain landscape with elevation less than 100 m a.s.l. The NCP comprises three distinct hydroge- ological settings within the Quaternary sediments (Fig. 1): the piedmont plain and associated major alluvial fans, the alluvial plains with many abandoned river channels, and the coastal plain strip around the margin of the Bohai Sea (Foster et al., 2004). The main stratigraphy of this region consists of unconsolidated Quaternary sediments with thickness ranging from 200 m to more than 600 m, comprising unconsolidated pebble, gravel, sand, silt, and clay. Groundwater occurs prin- cipally in the pores of the unconsolidated Quaternary sedi- ments. From the piedmont plain to alluvial and coastal plains in the middle-east portion of the NCP, the aquifer systems typically transistion from a single aquifer of sandy gravel to multiple aquifers of sand separated by silt or clay layers (Fig. 2).
inventory, investigation should be specifically oriented towards accurately delineating water table depth for depths less than 2 meters (Kumar, 2012). As in the study area depth of water level is found to be in between 7-14 meters below ground level therefore evapotranspiration from groundwater in the study area was found to be negligible as evapotranspiration effectively occurs at water level depth till 2 meters below ground level only.
Periodic maintenance of groundwaterrecharge structures is essential because infiltration capacity is rapidly reduced because of silting, chemical precipitation, and accumulation of organic matter. In the case of injection wells and connector wells, periodic maintenance of the system consists of pumping and / or flushing with a mildly acidic solution to remove encrusting chemical precipitates and bacterial growths on the well tube slots. By converting the injection or connector wells into dual-purpose wells, the time interval between one cleansing and another can be extended, but, in the case of spreading structures, except for sub-surface dykes constructed with an overflow or outlet, annual desilting is necessary. Unfortunately, because the structures are installed as a drought-relief measure, periodic maintenance is often neglected until a drought occurs, at which time the structures must be restored (the 5 to 7 year frequency of droughts, however, means that some maintenance does take place). Several agencies and individuals normally carry out structural maintenance.
The magnitude and frequency of recharge from ephemeral streams is dependent on the amount of water lost through infiltration into the wadi bed as the flood water progresses. These losses, known as the transmission losses, were computed using the rainfall- runoff model and measured floods during 1993 for Wadi Dhar. Several studies have reported transmission loss relations, for example Jordan (1977) found that transmission losses correlated well with flow volume at the upstream station. Other empirical relationships for transmission losses are given by e.g Burkham (1970), Lane et al (1971) . A review of a large number of American studies of transmission losses in remote ephemeral streams was reported in WRRC (1980). More recently, Sorman and Abdulrazzak (1993), using an existing data base for a "representative" basin in Saudia Arabia, suggested several regression equations relating transmission losses and flow height, width and duration on one hand, with recharge. Good relationships between recharge and transmission losses were obtained.
In general, there are three categories of models for the assessment of groundwater vulnerability: (1) index meth- ods or subjective rating methods, (2) statistical methods and (3) process-based modelling methods. Index-and-overlay methods are one set of subjective rating methods that uti- lize the intersection of regional attributes with the qualitative interpretation of data by indexing parameters and assigning a weighting scheme. The most widely used index method is DRASTIC (Aller et al., 1985). Unfortunately, index methods are based on subjective rating methods (Focazio et al., 2002) and should preferably be calibrated using measured prox- ies of vulnerability (Kihumba et al., 2015; Ouedraogo et al., 2016). When a groundwater monitoring data set is available, formal statistical methods can be used to integrate ground- water contamination data directly into the vulnerability as- sessment. Finally, process-based methods refer to approaches that explicitly simulate the physical, chemical and biologi- cal processes that affect contaminant behaviour in the envi- ronment. They comprise the use of deterministic or stochas- tic process-simulation models eventually linked to physically based field observations (e.g. Coplen et al., 2000). Physi- cally process-based methods are typically applied at small scales, mostly to define well protection zones, rather than to assess groundwater vulnerability at broader scales (Frind et al., 2006). A well-known example is the use of a physi- cally based groundwater model (e.g. MODFLOW; Harbaugh et al., 2000) that solves the governing equations of ground- water flow and solute transport. Such models have explicit time steps and are often used to determine the timescales of contaminant transport to wells and streams, in addition to the effects of pumping. However, they also have many parame- ters that require estimation. In this paper, we use statistical models to assess the vulnerability of groundwater systems to nitrate pollution.
Heuvelmans et al. (2006) compared the performance of a linear regression analysis and an artificial neural network (ANN) for regionalising the parameters of the hydrological model “SWAT”. They employed climatic, soil and land use data for the analysis, and consequently, a correlation analysis was performed to identify the correlations that the regionalisation scheme should reflect. An uncertainty assessment was also performed employing bootstrap sampling. Generally, the ANN delivered more accurate parameter estimates than the linear regression, with the exception of sites with catchment descriptors outside the range of descriptor values employed for the training process of the ANN. The performance of the regression was also affected under these conditions, however, the resulting error remained smaller for the regression approach. Regarding the uncertainty analysis, the ANN-based scheme presented larger uncertainties, a consequence of the greater amount of free parameters for the ANN structure compared to the regression model. Similar results were reported by Bastola et al. (2008). In their study, they aimed to regionalised parameters of hydrological models at a daily time scale, employing a new multi-objective regional calibration method (MORC), an ANN, a linear regression and a multiple polynomial regression. The higher uncertainty (assessed employing bootstrap sampling) was observed in the MORC, and compared to multiple regression-based schemes, the ANN resulted in considerable uncertainty. They noticed that ANNs and MLR have only limited capability to extrapolate outside the range over which they are trained or calibrated, however, the error employing a MLR is comparatively small.
Due to its large size, the freshwater lens on Andros Is- land represents the principal source of natural freshwater for the Bahamas. Most local residents rely on the munic- ipal potable water supply (< 0.4 g L −1 salt concentration), which extracts groundwater from the lens via 11 wellfields distributed across the island (Fig. 1). The local drinking wa- ter guidelines define potable water as having salt concentra- tions of less than 0.4 g L −1 . The largest of these wellfields is the North Andros Wellfield. As is common with many freshwater lenses, there is potential for upconing of the un- derlying saltwater and degradation of the lens if wells are deep and the lens thin (Werner et al., 2009; White and Falk- land, 2010). Therefore, the wellfields on Andros employ hor- izontal trench-based groundwater extraction or a series of in- terconnected shallow boreholes pumped at low rates. Typi- cal depth of the wellfields is between 1 and 5 m b.g.s. Wa- ter flows within the trench-based wellfields under a very low gradient, towards a central low sump where water is pumped to storage reservoirs.
CSIRO has formed a research alliance with the BoM in 2008 to compile and deliver comprehensive water information in the form of national water accounts and assessments, water forecasting products and water data services for the water sector. It is called WIRADA. Since 2008 CSIRO researchers have been developing the AWRA modelling system as part of WIRADA and supporting the BoM in the production of national water accounts and assessment reports. These reports provide an overview of water fluxes and storages at a national scale (Vaze et al. 2013). Alliance researchers have developed an integrated system for detailed water balance assessment from sub-catchment to continental scale, capturing water in the landscape, river systems and in groundwater. The state-of-the-art AWRA modelling system is able to tell us how much water has been produced, how much water is used by the environment or through irrigation, how much water we have left, how this compares with the past, and whether extractions, land use, farm dams or bushfires are having an impact on water security and the environment. It draws on a wide range of on-ground and remote sensing data, to provide unprecedented coverage and insights into Australia’s water resources system. The scale of this endeavour requires ongoing innovation in model development, calibration, data assimilation and remote sensing.