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Loess is a type of Quaternary sediments of the wind origin in arid and semi-arid regions. This type of sediment is widely and thickly distributed in China, forming the Loess Plateau, which is the largest bulk accumulation of loess on the Earth. The Loess Plateau of China has received great attention from scientific communities, including geologists, geophysicists and engineers worldwide. Accordingly, a wealth of investigations has been undertaken on various problems arising in this area. However, some scientific questions remain relevant and unresolved. These questions mainly present in the areas of evolution and surface processes of loess landform, depositional environments of loess sediments, impacts due to Neotectonics and fault activities in loess areas, and natural and man-made geohazards. In recent years, extensive innovative studies have been carried out to further understand the above-mentioned topics. Substantial new data, theories and insights have become available. This special issue provides a timely overview on the recent case histories, theoretical advances, laboratory and field testing and state-of-art methods in the theme of loess geology and surface processes. The papers gathered in this special issue are introduced in this article.

An improved Vernier time-to-digital converter (TDC) with overflow bits is designed for low power applications. The overflow bits are added to the Vernier-TDC to reduce the stages of the TDC, thus saving power. A digital-to-time convertor is employed to realize the fractional division and reduce the stages of TDC. Fabricated in 55-nm CMOS, TDC together with DTC consumes only 360 μW when operating at 24 MHz. With the help of the TDC, the ADPLL achieves 1.69-ps rms jitter with a 24-MHz reference clock and a 1.8GHz output RF clock.

Due to coal mining taking place on a large scale in northern China, it is inevitable that wide-spread dewatering occurs in the aquifers overlying the resulting goaf. The purpose of this paper is to protect the groundwater of overlying unconsolidated aquifers. Based on physical model experiment, seepage experiments, and numerical simulation, this paper determines the patterns and distribution of the overburden rocks in the goaf, establishes the correlation between the fracture ratio and the hydraulic conductivity of the rock mass, and characterizes the groundwater flow pattern. The results show that (1) the residual fracture occurring ratio within the residual fracture zone is approximately 1.82 times that of the fracture compaction zone and 1.93 times that of the coal wall support zone; (2) the hydraulic conductivity of the rock mass in different parts of the goaf increases with increasing fracture ratio, the relationship of the two follows a power curve; (3) the predicted groundwater levels from numerical simulation is good fit with the measured and indicates that the hydraulic conductivities derived from seepage experiments are rational. We demonstrate how a laboratory-scale physical model can be used effectively to verify existing conceptual models in such a way that the impact of coal mining on groundwater resources can be predicted for similar regions.

This paper derives an equivalent of Darcian Theis solution for non-Darcian flow induced by constant rate pumping of a well in a confined aquifer. The derivation, which is valid at later times only, is original. It utilizes Izbash's equation. This introduces an additional parameter to Darcian condition, namely, empirical exponent. The solution is a non-Drcian equivalent of Jacob straight line method for analyzing pumping tests at late times. It can be used to determine aquifer parameters: storativity, analogous hydraulic conductivity, and empirical exponent. However, while the Jacob method requires a minimum of only one pumping test with one observation well, the additional parameter in the present solution means that a minimum of two observation wells in one test or two pumping tests at different rates with one observation well are required. The derived solution is applied to a case study at Plomeur in Brittany, France, and is shown to provide a practical and efficient method for analyzing pumping tests where non-Darcian groundwater flow occurs.

Reducing ineffective evaporation is a feasible means to improve water use efficiency in agriculture, especially in arid and semi-arid areas. A field experiment assessed the impact of sand mulches (1-cm thickness) with a particle size of 0.5–1.5 mm (XS) and 1.5–2.0 mm (CS) on soil evaporation during winter in Northern China. Results showed that CS and XS increased by at least 11.93% and 14.92% compared to bare soil (LD), respectively. However, the sand mulches showed significant distinctions in soil evaporation at different stages. Soil evaporation was the highest in LD, while CS evaporated the least in the unstable freezing stage (P1) and stable freezing stage (P2); in the thawing stage (P3), XS evaporated the most, while LD evaporated the least. Ten factors affecting evaporation were analyzed using the principal component analysis method to elaborate the mechanisms of soil evaporation. Mean soil moisture at depths from 0 to 15 cm was a factor that affected the evaporation of XS and CS in the test. Soil moisture was evaporated by vapor when the frost penetration was dense and the frost impeded the vapor movement. The evaporation rates were steady and weak in this period, and soil moisture had slight impact on soil evaporation, especially XS and CS treatment with higher water content at the surface. The research is significant for preventing evaporation and the improvement of water-use efficiency.

During freeze–thaw periods, the exchange between shallow groundwater and soil water is unusually strong and bidirectional, which causes soil salinization and affects the accuracy of water resources assessment. The objectives of this study were to explore the laws of transformation between phreatic water and soil water through nine different groundwater table depths (GTDs) and three kinds of lithologies during three successive freeze–thaw periods using field lysimeters. The results showed that phreatic evaporation increased with smaller average soil particle sizes. The differences between phreatic evaporation and recharge to groundwater (DPR) and GTDs were well fitted by the semi-logarithmic model, and the regression coefficients A and B of the model were well fitted by the linear relationship with the average soil particle size. With the increase of soil particle size, the change of DPR decreased with the change rate of soil particle size. The extent of transformation between phreatic water and soil water decreased with the increase of soil particle size. During the whole freeze–thaw period, the negative value of DPR increased with an decrease in GTD. The groundwater depths of zero DPR (D-zero) of sandy loam, fine sand and sandy soil during the freeze–thaw periods were 2.79 m, 2.21 m and 2.12 m, respectively. This research is significant for the prevention of soil salinization disasters and the accurate assessment of water resources.

Permanent or long-term large shareholders have different governance incentives and mechanisms from institutional investors. Liquidity could facilitate either cutting and running by large shareholders or, alternatively, increased monitoring. Using an exogenous shock to liquidity in China, we document evidence of no cutting and running. We find that board members representing large shareholders become less busy and more diligent, while busyness and diligence of independent directors are not affected by liquidity. Large shareholders also improve compensation contracts by increasing pay-performance sensitivity. These effects are more pronounced when gains from monitoring are higher or monitoring is less susceptible to the free-rider problem.

The brainstem locus coeruleus (LC), the primary norepinephrinergic (NE) nucleus in the brain, has been implicated in the abuse of drugs such as opioids. However, whether and how the LC-NE system is involved in cocaine addiction remains elusive. Here, we demonstrated cocaine-evoked synaptic plasticity of glutamatergic transmission onto LC neurons as one of the earliest traces occurring after a single injection of cocaine. Twenty-four hours after mice were injected intraperitoneally with cocaine, the evoked α-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid receptor (AMPAR) mediated synaptic transmission onto LC neurons were strongly potentiated without major effect on N-methyl-d-aspartate receptor (NMDAR) mediated synaptic transmission. Compared with saline-pretreated mice, AMPAR-mediated excitatory postsynaptic currents (EPSCs) of cocaine-pretreated mice showed a marked inward rectification, demonstrating the insertion of GluR2-lacking AMPARs to plasma membrane. In addition, the single injection of cocaine did not affect presynaptic glutamate release probability measured by paired pulse ratio. Furthermore, we found that the cocaine-induced potentiation of AMPAR EPSCs could be blocked by prazosin, an inhibitor of α1-adrenoreceptor (AR), indicating that cocaine increases AMPAR transmission via α1-ARs. These results reveal that LC-NE serves as an initial target of drug intake.

This study explores the hydrogeochemical evolution of karst groundwater in the Jinci Spring region, Shanxi Province, northern China. During 2015, karst groundwater samples collected from 24 sampling points along several profiles that follow the groundwater flow direction were subjected to hydrochemical analysis. Reaction paths and mineral phases for the hydrogeochemical modeling were determined based on the analysis results and in conjunction with the regional geology and hydrogeology. The PHREEQC hydrogeochemical modeling software was used to perform mass balance and reaction path modeling of the hydrogeochemical evolution of the spring region. The modeling results showed that from the recharge area through the runoff area to the drainage area, the hydrogeochemical processes occurring in the karst water vary widely between the northeastern, central, and southwestern parts of the spring region, and across the piedmont discharge area. Additionally, hydrodynamic fields and geological structures were found to have significant control over the hydrogeochemical reactions occurring within the spring region’s karst groundwater.

Accurate forecasting of annual runoff is necessary for water resources management. However, a runoff series consists of complex nonlinear and non-stationary characteristics, which makes forecasting difficult. To contribute towards improved prediction accuracy, a novel hybrid model based on the empirical mode decomposition (EMD) for annual runoff forecasting is proposed and applied in this paper. Firstly, the original annual runoff series is decomposed into a limited number of intrinsic mode functions (IMFs) and one trend term based on the EMD, which makes the series stationary. Secondly, it will be forecasted by a least squares support vector machine (LSSVM) when the IMF component possesses chaotic characteristics, and simulated by a polynomial method when it does not. In addition, the reserved trend term is predicted by a Gray Model. Finally, the ensemble forecast for the original runoff series is formulated by combining the prediction results of the modeled IMFs and the trend term. Qualified rate (QR), root mean square errors (RMSE), mean absolute relative errors (MARE), and mean absolute errors (MAE) are used as the comparison criteria. The results reveal that the EMD-based chaotic LSSVM (EMD-CLSSVM) hybrid model is a superior alternative to the CLSSVM hybrid model for forecasting annual runoff at Shangjingyou station, reducing the RMSE, MARE, and MAE by 39%, 28.6%, and 25.6%, respectively. To further illustrate the stability and representativeness of the EMD-CLSSVM hybrid model, runoff data at three additional sites, Zhaishang, Fenhe reservoir, and Lancun stations, were applied to verify the model. The results show that the EMD-CLSSVM hybrid model proved its applicability with high prediction precision. This approach may be used in similar hydrological conditions.

Parameter estimates of artesian aquifers where piezometric head is above ground level are largely made through free-flowing and recovery tests. The straight-line method proposed by Jacob-Lohman is often used for interpretation of flow rate measured at flowing artesian boreholes. However, the approach fails to interpret the free-flowing test data from two artesian boreholes in the fractured-rock aquifer in Table Mountain Group (TMG) of South Africa. The diagnostic plot method using the reciprocal rate derivative is adapted to evaluate the artesian aquifer properties. The variation of the derivative helps not only identify flow regimes and discern the boundary conditions, but also facilitates conceptualization of the aquifer system and selection of an appropriate model for data interpretation later on. Test data from two free-flowing tests conducted in different sites in TMG are analysed using the diagnostic plot method. Based on the results, conceptual models and appropriate approaches are developed to evaluate the aquifer properties. The advantages and limitations of using the diagnostic plot method on free-flowing test data are discussed.

Sustainable-yield estimation in semi-arid conditions is always challenging, especially for fractured rock aquifers. An approach to assess sustainability is discussed using a case study from rural semi-arid Namibia. The fractured-rock aquifers in the study area have complex configuration. Geology maps, hydrocensus data, geophysical surveys, and drilling and hydraulic testing data were used to produce a conceptual model. Aquifer parameters were estimated based on the hydraulic test data and numerical modelling. Due to lack of data, as is often the case in rural Namibia, the simulation results had to be verified against geological and hydrogeological constraints. It is concluded that the aquifer system is sustained by episodic recharge and the long-term gain in storage (about 3,285 m3/a) represents the maximum extractable volume. It is recommended that the continuous monitoring system for groundwater level, river flow and rainfall should be part of a long-term scheme. The magnitude and frequency of the recharge events and extraction should be monitored in order to sustainably manage the resource. Although the illustrated approach is based on limited data, it provides a basis for management of individual groundwater schemes in semi-arid conditions in sub-Saharan Africa.

Purpose: This study aimed to determine the changes in lower extremity biomechanics during running-induced fatigue intervention. Methods: Fourteen male recreational runners were required to run at 3.33 m/s until they could no longer continue running. Ground reaction forces (GRFs) and marker trajectories were recorded intermittently every 2 min to quantify the impact forces and the lower extremity kinematics and kinetics during the fatiguing run. Blood lactate concentration (BLa) was also collected before and after running. Results: In comparison with the beginning of the run duration, (1) BLa significantly increased immediately after running, 4 min after running, and 9 min after running, (2) no changes were observed in vertical/anterior&ndash, posterior GRF and loading rates, (3) the hip joint range of motion (&theta, ROM) significantly increased at 33%, 67%, and 100% of the run duration, whereas &theta, ROM of the knee joint significantly increased at 67%, (4) no changes were observed in ankle joint kinematics and peak joint moment at the ankle, knee, and hip, and (5) vertical and ankle stiffness decreased at 67% and 100% of the run duration. Conclusion: GRF characteristics did not vary significantly throughout the fatiguing run. However, nonlinear adaptations in lower extremity kinematics and kinetics were observed. In particular, a &ldquo, soft landing&rdquo, strategy, achieved by an increased &theta, ROM at the hip and knee joints and a decreased vertical and ankle stiffness, was initiated from the mid-stage of a fatiguing run to potentially maintain similar impact forces.

Due to severe droughts and rapid urbanization, Cape Town municipality including small towns along the West Coast of South Africa are facing water shortages. Managed aquifer recharge (MAR) seems to offer a solution to improve water security in this drought-prone area. This paper presents a conceptual framework within which numerical modelling of the aquifers system is operated to improve water security of West Coast. The ModelMuse software that included MODFLOW and MODPATH packages was used. Scenarios which considered recharge aspects were used to evaluate suitable sites and appropriate scheme of implementing MAR. The result showed that it is feasible to implement MAR in the upper unconfined aquifer unit (UAU) which had estimated available space for MAR of 915.7 million m3. For the semi-confined lower aquifer unit (LAU), the clay-missing window area located at west of Hopefield was a suitable site to implement MAR. However, the prevailing little space in LAU to store recharged water was a limiting factor to support the implementation of MAR scheme. Details on the possibility of implementing MAR scheme for West Coast aquifers system were discussed based of the simulations that were carried out. Although the modelling approach does not provide precise areas but a management tool, it provides key insights that are applicable in aquifer systems of similar characteristics.

Prediction of response to fissure water pumping from a shaft on the surrounding areas is conducted with a numerical model, which was refined using environmental stable isotope (ESI), Tritium and hydrochemical datasets. The numerical model domain covers the local carbonate rock units mainly because it is known to be the main source of groundwater. Based on the hydrochemical dataset of the fissure water pumped at the shaft, strong signature of Na–Cl type water originating from the seepage of a waste rock dump as well as polluted water from mine offices, loading/unloading and parking lot areas, is evident. The environmental isotope data demonstrated that fissure water intercepted at the shaft has strong footprint of surface water and polluted groundwater from nearby areas. The 30-year numerical model prediction indicates that pumping at a rate of 2500 m 3 /day or more would cause the radius of influence to expand to areas where the central tailings storage facility is located and could possibly draw highly acidic water. Interception of acid rock drainage could cause sever corrosion of pump infrastructure, enhance dolomite dissolution and local ground subsidence as well as possibly compromise the structural integrity of the central tailings dam . It is recommended that the current groundwater monitoring network be revised for taking proactive action. The study highlights the relevance of integrating various sets of data to improve understanding of the conceptual flow before any numerical modelling is attempted.

Towns along the West Coast of South Africa are facing water shortages due to climate change and increasing water demand. Managed aquifer recharge (MAR) is considered as a solution to improve water security. This paper presents a two-step method of combining geographic information system (GIS) based analysis with numerical modeling to select suitable sites for implementing MAR in the West Coast area. Many factors were taken into account to generate the initial map for suitable sites through GIS based analysis. Subsequently, groundwater flow modeling was adopted to verify and optimize the suitable sites selected by GIS based analysis. The result showed that the map for suitable sites produced by the GIS based analysis was reasonable from a spatial aspect, but due to the lack of groundwater seepage information, the most suitable sites developed are not necessarily the optimal choices in practice. With the aid of both the spatial analysis in GIS and seepage simulation, this two-step analysis approach provides a reliable solution to identify suitable sites for implementing MAR. This approach provides a much better reference to the study of suitable sites and possible impacts of implementing MAR in an aquifer in similar areas with water stress.

It is important to understand how groundwater recharge responds to precipitation variability in space and time, especially in those areas such as Yanqing Basin (China), where groundwater represents the sole water resource. A simple soil-water balance method is applied for spatio-temporal simulation of groundwater recharge in Yanqing Basin from 1981 to 2000. It was implemented on a monthly time step considering the effects of land use and soil texture. The area-average recharge associated with various land uses and soil textures was then compared with zonal analysis using a geographic information system (GIS). The main findings include: (1) the variation of groundwater recharge follows precipitation changes, either at yearly or seasonal intervals, (2) land use plays a more influential role in groundwater recharge than soil texture in this area, and (3) the water table quickly rises in response to recharge in the shallow parts of the aquifer, while there is a delay of 0.5–1.0 years where the groundwater level is at depth 4–10 m. The application demonstrates how spatio-temporal analysis can be utilized for groundwater-recharge estimation through distributed modeling and GIS.

The average cash holdings of Chinese-listed firms decreased significantly after the split share structure reform in China, which specified a process that allowed previously nontradable shares held by controlling shareholders to be freely tradable on the exchanges. The reduction in cash holdings is greater for firms with weaker governance and firms facing more financial constraints prior to the reform. The reform also significantly reduced the average corporate savings rate, as measured by cash-to-cash-flow sensitivity. These findings are consistent with the premise that the reform removed a significant market friction, which led to better incentive alignment between controlling shareholders and minority shareholders and relaxed financial constraints. Additional analyses show that the reform affects firms' cash management policies, investment decisions, dividend payout policies, and financing choices differently in private firms than in state-owned enterprises. The Author 2012. Published by Oxford University Press on behalf of The Society for Financial Studies. All rights reserved. For Permissions, please e-mail: journals.permissions@oup.com., Oxford University Press.

Groundwater/surface-water interaction is receiving increasing focus in Africa due to its importance to ecologic systems and sustainability. In South Africa’s 1998 National Water Act (NWA), water-use licenses, including groundwater, are granted only after defining the Reserve, the amount of water needed to supply basic human needs and preserve some ecological integrity. Accurate quantification of groundwater contributions to ecosystems for successful implementation of the NWA proves challenging; many of South Africa’s aquifers are in heterogeneous and anisotropic fractured-rock settings. This paper reviews the current conceptualizations and investigative approaches regarding groundwater/surface-water interactions in the context of South African policies. Some selected pitfall experiences are emphasized. The most common approach in South Africa is estimation of average annual fluxes at the scale of fourth-order catchments (∼500 km2) with baseflow separation techniques and then subtracting the groundwater discharge rate from the recharge rate. This approach might be a good start, but it ignores spatial and temporal variability, potentially missing local impacts associated with production-well placement. As South Africa’s NWA has already been emulated in many countries including Zambia, Zimbabwe and Kenya, the successes and failures of the South African experience dealing with the groundwater/surface-water interaction will be analyzed to guide future policy directions.

In Africa, groundwater plays an increasingly important role as a source of potable water, more so in rural communities where the cost implication of routing surface water supplies may far exceed the budgets of local water service authorities. Protection of groundwater resources requires good planning and a concerted effort from the legislative level right down to the enforcement and implementation level. The latter is essential in site-specific management and circumventing potential health threats that may result from the consumption or contact with contaminated groundwater. The reality in sub-Saharan Africa unfortunately is that these institutional structures do not exist and where they do exist implementation is problematic. This paper advocates that whilst zonal protection of groundwater resources is theoretically a good management option for protection of groundwater resource quality, practically its successful implementation can only be carried out once many of the sub-Saharan countries have their legal, institutional and socioeconomic frameworks in place. However, whilst working towards achieving those objectives even protection at a basic level like the implementing of minimum setback distances around groundwater resources and paying close attention to borehole development standards will offer sufficient basic protection to these vital resources.

Groundwater studies in several African countries show that the contamination of water-supply aquifers is mainly due to improper placement of land-based activities such as agriculture, industries, waste disposal. In South Africa, groundwater pollution is also of increasing concern due to fast population growth and accompanying development. Groundwater protection zoning is a supplemental methodology for groundwater management that incorporates land use planning. The land is managed to minimize the potential of groundwater contamination by human activities that occur on or below the land surface. The various benefits associated with implementation of protection zoning are discussed for stakeholders such as communities, water supply companies, ecosystems and policy makers. A South African case study is presented comparing the cost of protection with the cost incurred due to the treatment of sick and dying people due to contaminated drinking water. These benefits must be communicated to the stakeholders to start the implementation at all management levels. Implementation steps of groundwater protection zones are discussed and can be tested even with low budgets and little data available. Monitoring and reassessment of protection zones are important to test the effectiveness and prove to decision makers that the money was well spent. The legal framework for implementation of groundwater protection zoning in a South African context is described, where the water law makes provision for tools like differentiated protection, licensing and recovery of cost. Challenges regarding implementation of groundwater protection are discussed with some action steps on how to move forward.

Core samples from an 800-m deep borehole at the Rietfontein Farm, 10 km west of Graafwater, Western Cape, South Africa, were examined and interpreted for the hydrogeological significance of the Table Mountain Group (TMG) in the area. A suite of fracture data was collected and analysed to characterize the aquifer and conceptualize flow in the vicinity of the hole. Based on these data, the hydraulic conductivity, and density and coating intensity (due to precipitation) of the fractures against depth were computed. The dependence of fracture density on depth is very weak, while the intensity of fracture coatings is closely linked to the distribution of hydraulically active fractures that represents the maximum number of fractures currently open to groundwater flow. Four scenarios of depth ranges reflecting the development of hydraulically active fractures are proposed as a depth model of groundwater flow, implying that the majority of groundwater exists above 400 m depth. The top of the hydraulically inactive fracture zone clearly indicates that no groundwater flow could take place below a depth of about 570 m. The depth model gives a better understanding of the properties of the aquifers in the area and improves conceptual models, considering the lower limit of aquifer depth in particular.

Temporary wetlands are an ecologically and economically important habitat in South Africa. They harbor large branchiopods, known to be flagship species of nonpermanent aquatic habitats, and sensitive to land use changes. In this study we review the current status of large branchiopods in the Western Cape, a South African province subject to increasing agriculture and urbanization. We studied the species diversity and distribution of large branchiopods by sampling 58 temporary wetlands in an area covering about 30% of the Western Cape. Information obtained from field samples was supplemented by incubating resting egg banks from the sampled wetlands. Our data were compared with all known distribution records for large branchiopods in the target region. Based on this combined information, the International Union for the Conservation of Nature and Natural Resources (IUCN) Red List category was assessed for each species. Four of the eight large branchiopod species known to occur in the sampling area were collected. Of all wetlands sampled, 40% harbored large branchiopods. Most anostracan populations were small, and species co-occurred in only one wetland. From the entire Western Cape, 14 species have been recorded in the past. Two of these are already included in the IUCN Red List. Insufficient data are available to determine the IUCN Red Data Category of six other species. A large variation in the telsonic appendages of S. dendyi was found across the studied area. In view of possible ongoing speciation and subsequent radiation, individual populations need protection. Since little information is available, it is difficult to evaluate recent changes in the conservation status of large branchiopods. Their populations are currently very low and have probably diminished in the last few decades. More knowledge about the functioning of temporary systems is needed to manage these vulnerable habitats and conserve their threatened species.

The Sakumo wetland is an internationally recognized Ramsar site located in a largely urban area and provides essential ecological and social services to wetland community dwellers. Despite its importance, the wetland has over the years been subjected to human interference resulting in considerable risks of deteriorating water quality, biodiversity loss, and drying up of most parts of the wetland. The conversion of land for residential and agricultural uses has significantly altered the hydrological characteristics of the land surface and modified pathways and flow of water into the wetland. Other drivers identified included drainage (mainly as runoff from agricultural farms), anthropogenic pressure (waste discharge) due to infrastructure development associated with urbanization, chemical contamination as a result of industrial and household pollution, and unsustainable fishing practices (overfishing). The purpose of the study was to review some of the physical and chemical properties of the Sakumo wetland on the changing wetland resources with emphasis on water quality. Rapid urbanization, industrialization, and overexploitation of wetland resources were identified as key causative factors affecting the wetland functions. Their effects on the wetland among others include increased nutrient and toxic chemical load which has resulted in reduced wetland surface water quality and decrease in species diversity. pH of the wetland waters was generally alkaline which is characteristic of water bodies influenced by seawater under oxygenated conditions. The increasing trends of electrical conductivity, phosphates, ammonia, nitrate, and nitrite, though small, point to deteriorating water quality in the wetland. The lagoon water was observed to be heavily polluted with nutrients particularly phosphate. The sequence of nutrient in the wetland was found to be in the order of PO4-P>NH3-N>NO3-N>NO2-N. These, if not checked, will result in further deterioration of the wetland function. In order to protect the wetland structure and function, it is recommended that a determination for both surface water and groundwater (quality and quantity) components of the ecological reserve (aquatic ecosystem) as well as the basic human need should be undertaken. In addition, a complete hydrological study of the wetland must be done. This will enable a well-balanced water allocation scheme to all users while still ensuring long-term survival and sustainability of the wetland.

The purpose of this paper is to investigate whether a simple, spatially-based approach to groundwater sustainability using radius of influence should be used to replace the pervasive, yet deprecated, ‘natural recharge water balance’ volumetric method. Using South Africa as a case study, the radius of influence methodology was shown to be scientifically practical, to provide plausible results, and to be permissible under the country’s water laws. The approach also provides better indicators for institutions involved in groundwater management, and remains conceptually correct at all scales. However, further research is recommended on more robust alternatives to the Cooper-Jacob equation for determining radius of influence. Keywords : groundwater, sustainability, spatial, water balance, indicators, institutions

The exchange between shallow groundwater and soil water is unusually strong during freeze-thaw periods. The purpose of this study is to determine the effect of four different groundwater table depths (GTDs) and two soil textures on soil water moisture migration and phreatic evaporation during a freeze-thaw period using lysimeters. The results show that a high-moisture zone (HMZ) formed at a depth of 25–35 cm for sandy loam with a soil moisture content of 52%, while no obvious HMZ formed for fine sand when the GTD was 0.5 m. When the GTD was 2.0 m, a HMZ formed at a depth of 50–70 cm for sandy loam at the highest soil moisture content of 22%, while a HMZ formed at a depth of 60–80 cm for fine sand with a soil moisture content of 10%. The cumulative phreatic evaporation increased by a power function on freezing days during the freezing period. The total phreatic evaporation for sandy loam declined linearly with the increasing of GTD, and with the largest evaporation value of 73.6 mm for fine sand when the GTD was 1.0 m during the freeze-thaw period. The research would be significant for water resource assessment, the conversion of farmland water, and the prevention of saline land.

Due to climate change and human activities over the last fifty years, the spring flow volume of karst groundwater has sharply diminished in China. Climate change is one of the critical factors that initiates a series of karst hydrogeologic and water ecological environmental problems, because the precipitation shows a decreasing trend while the temperature shows an increasing trend. The Jinci Spring is one of the largest, most famous springs in northern China. This study employed data from the Taiyuan Meteorological Station and ten precipitation stations in and around the Jinci Spring region as well as the runoff data gathered from two hydrological monitoring stations during 1960–2012. The sliding average method and the Mann-Kendall test were used to analyze the variation tendency of precipitation, temperature, and land evaporation in this area. Finally, the following were calculated: the varying pattern of the karst groundwater recharge amount and the response of the recharge amount to precipitation, land evaporation, and river runoff by quantitative analysis. The results indicated that the precipitation and land evaporation amount decreased at first and then subsequently increased. Likewise, the variation trend of the karst groundwater recharge amount in the spring region was roughly consistent with the precipitation variation pattern. In contrast, the temperature displayed an increasing trend. The climate change resulted in a reduction of the karst groundwater recharge amount, and it had the greatest influence in the 1990s, which caused the karst groundwater recharge amount to decrease 26.75 mm as compared to that of the 1960s (about 39.68% lower than that of the 1960s). The Jinci Spring had zero flow during this period. The reduction in precipitation was one of main factors that caused the cutoff of the Jinci Spring.

Accurate parameter estimation for aquifers is very challenging, particularly for artesian aquifers in which the potentiometric surface is above ground level. A common approach to parameter estimation for artesian aquifers is to make use of free-flowing and recovery tests. However, such aquifer tests on artesian boreholes are seldom carried out due to lack of an appropriate device readily available for data collection. This paper describes a hydraulic test device for recording flow rate, pressure, EC and pH measurements using an ultrasonic flowmeter, pressure transmitter, EC and pH meters. A procedure to set up the device in the field is outlined. To test the device, an artesian borehole in the Table Mountain Group (TMG) aquifers of South Africa was chosen as a case study, where the device was applied to measure and record flow rate and pressure of the aquifer, as well as EC and pH. Compared with previous free-flowing test data measured manually, the flow data captured by the device was accurate and reliable, and can be utilised to estimate the hydraulic properties of an artesian aquifer. The advantages and disadvantages of the device are discussed, followed by suggestions for improvement. Given that a large number of flowing artesian boreholes are present in the TMG area in which the pressure head of the aquifer is often above ground level, the applicability of the device presented is likely to be widespread. With due improvement of the test device, its wider application in similar conditions, e.g. to artesian holes in the Karoo, would be expected in future. Keywords : flowing artesian borehole, hydraulic test device, free-flowing test, TMG aquifers, data capture

The simplest way to derive an estimate for the sustainable yield of a borehole is to study the behaviour of drawdowns observed during a hydraulic (also known as a pumping test) of the borehole, through an appropriate conceptual model. The choice of this model is probably the most difficult choice that the analyst of such a hydraulic test has to make, since a wrong model can only lead to the wrong conclusions and failure of the borehole. This paper discusses a semi-analytical and two numerical methods that can be used to simplify the analyses of hydraulic tests in fractured rock formations. The first method, called the Method of Derivative Fitting (MDF), uses a new approach to identify the conceptual model needed in such analyses. This is achieved by characterizing the various flow periods in fractured rock aquifers with numerical approximations of the first logarithmic derivative of the observed drawdown (the derivative of the drawdown with respect to the logarithm of the time). Semi-analytical expressions are used to estimate the influence that boundaries may have on the observed drawdown and the sustainable yield of a borehole — the rate at which a borehole can be pumped without lowering the water level below a prescribed limit. An effort has also been made to quantify errors in the estimates introduced by uncertainties in the parameters, such as the transmissivity and storativity, through a Gaussian error propagation analysis. These approximations and the MDF, called the Flow Characteristics Method (FCM) have been implemented in a user-friendly EXCEL notebook, and used to estimate the sustainable yield of a borehole on the Campus Test Site at the University of the Orange Free State. The first numerical method, a two-dimensional radial flow model, is included here because it allows the user more freedom than the FCM, although it requires more information. One particular advantage of the method is that it allows one to obtain realistic estimates of the storativity and transmissivity of Karoo aquifers in particular, which is required in the estimation of the sustainable yield of a borehole. There is no doubt that a three-dimensional numerical model, the second numerical method discussed here, is the best method with which to analyse a hydraulic test in a fractured aquifer. The method was consequently used to evaluate the accuracy of the implementation of the MDF in the Excel notebook and its application to the borehole on the Campus Test Site. The good agreement between the sustainable yield estimated with the three-dimensional numerical model and the FCM indicates that the FCM can be used with confidence to estimate the sustainable yields of boreholes in fractured media.

Diagnostic derivative interpretation of drawdown data from pumping tests is discussed in this paper. An emphasis is placed on the conceptualization of derivative term of dlgs/dlgt. Use of a combined plot of dlgs/dlgt and ds/dlgt is made to identify various flow patterns from variable discharge tests with infinite conditions, constant rate tests in bounded aquifers, and tests involving double porosity, which can be used to further characterize the aquifer. Compared with the standard derivative method (ds/dlgt), the combined derivative analysis of dlgs/dlgt and ds/dlgt of drawdown behaviours possesses certain advantages identified as follows: (1) the plot of dlgs/dlgt is strikingly sensitive for use in unveiling differences between pumping and recovery periods in a variable discharge test; (2) storativity (S) of pumped aquifers can be accurately evaluated by the combined plot; and (3) a quantitative assessment of double porosity behaviour can also be achieved. Based on applied case studies, Lagrange Interpolation Regression (LIR) is recommended for numerical derivative calculation. Advantages and disadvantages of LIR and traditional methods are demonstrated via a selected case study. The result of the case study confirms that LIR is a preferred method for numerical derivative calculation as it can be used to effectively minimise noisy effect during derivative processes. The proposed derivative approach provides the hydrologists with an additional tool for characterizing pumped aquifers.

This paper explores the nature, source and spatial variation of the salinity of water used for irrigation in a coastal urban farming area in Cape Town, South Africa, where water from the Cape Flats aquifer is drawn into storage ponds and used for crop irrigation. Water samples were collected in summer and winter from selected sites across the study area and were analysed for salinity as well as for concentrations of major and minor ions. Each site consists of one borehole and one pond. Isotope analysis was done for the summer samples so as to assess effects of evaporation on water quality and salinity. Descriptive statistics were used to compare the variation in range of concentration of specific ions with the recommended ranges set by the South African Department of Water Affairs and Forestry (DWAF) and the Food and Agriculture Organisation (FAO). Geographical information system (GIS) analysis was used to describe the spatial distribution of salinity across the study area, and hydro-geochemical analysis was used to assess the possibility of seawater intrusion into the aquifer system and to characterise groundwater in the study area. The results of the research showed that the concentrations of chloride, nitrate, potassium and sodium exceeded the target maximum limit according to DWAF and FAO guidelines. Groundwater and pond water were also observed to be brackish in most parts of the research area in terms of total dissolved salts content, and fresh water was only found in the middle section of the research area. It is concluded that the accumulation of salts in groundwater and soil in the study area is mainly due to the agricultural activities and partially due to the natural movement of water through the geological formation of the Cape Flats region. These findings permit the formulation of a conceptual model of the occurrence of the salinization process, which implies that the groundwater and pond water in the study area are generally suitable for irrigation purposes, but need to be used with caution as the vegetables grown are classified as sensitive and moderately sensitive to salt according to DWAF guidelines for irrigation water quality (1996). The research paves a way for possible quantitative simulation of salt mass balance in future.Keywords: South Africa, Philippi farming area, salinity, groundwater, irrigation water, hydrochemical analysis, isotopic analyses, evaporation, suitability

Recharge estimation in arid and semi-arid areas is very challenging. The chloride mass balance method applied in western South Africa fails to provide reliable recharge estimates near coastal areas. A relationship between rainfall events and water level fluctuations (WLF) on a monthly basis was proposed in the rainfall infiltration breakthrough (RIB) model for the purpose of groundwater recharge estimation. In this paper, the physical meaning of parameters in the CRD and previous RIB models is clarified, and the RIB model is reviewed with the algorithm improved to accommodate various time scales, namely, daily, monthly and annual scales. Recharge estimates on a daily and monthly basis using the revised RIB approach in 2 study areas, one in a sandy alluvial aquifer (Riverlands) and the other in the Table Mountain Group (TMG) shallow unconfined aquifer (Oudebosch), are presented, followed by sensitivity analysis. Correlation analysis between rainfall and observed WLF data at daily scale and monthly scale, together with recharge estimates obtained from other methods, demonstrates that the RIB results using monthly data are more realistic than those for daily data, when using long time series. Scenarios using the data from Oudebosch with different rainfall and groundwater abstraction inputs are simulated to explore individual effects on water levels as well as recharge rate estimated on a daily basis. The sensitivity analysis showed that the recharge rate by the RIB model is specifically sensitive to the parameter of specific yield; therefore, the accurate representative specific yield of the aquifer needs to be selected with caution. The RIB model demonstrated in these two cases can be used to estimate groundwater recharge with sufficiently long time series of groundwater level and rainfall available in similar regions. In summary, the RIB model is best suited for shallow unconfined aquifers with relatively lower transmissivity;the utility of the RIB model for application in different climatic areas under different hydrogeological conditions needs to be further explored.Keywords: RIB model, shallow unconfined aquifer, groundwater-level fluctuation, groundwater recharge,Table Mountain Group aquifer

One of the principal environmental concerns relating to coal combustion waste disposal is the potential for groundwater contamination from salt fluxes and trace elements that may be leached into the underlying groundwater system. Since changes in moisture and salt concentrations usually provide contrasts in electrical properties against the host media, electrical resistivity methods can be used to monitor ingression of solute plumes as well as to detect any preferential flow paths within the ash medium. In this study, 2D electrical resistivity tomography was used to monitor brine (10% NaCl) water ingression through the unsaturated zone of a dry coal ash dump at a power station, Mpumalanga, South Africa. This was after the initial laboratory determination of the relation between electrical resistivity and moisture/salt content for the ash dump. The results showed that infiltration plume progression was more pronounced in the vertical direction, suggesting that moisture movement is mainly due to gravitational pull. There was no evidence of preferential flow within the ash medium, although the different infiltration rates for different sites suggested different permeability within the unsaturated zone.Keywords: coal ash dumps, brine infiltration, cementation factor, electrical resistivity tomography, time lapse survey

In rural Africa, scientific evidence is often lacking to guide the scaling-up of groundwater as the safest source of potable water. An investigation was conducted in the Upper Limphasa Catchment in northern Malawi to determine the safety of groundwater sources and to explore factors influencing water quality. Water samples from 17 boreholes, 6 hand-dug wells and 90 households were analysed for selected parameters. Portable incubators, multi-parameter probe and colorimetric standard methods were used for field measurements, and standard methods were used for laboratory water analysis. Results were compared to specified guidelines of the World Health Organization and Malawi Bureau of Standards to establish the potability of water. Statistical results using non-parametric t-tests indicated that the wells were more contaminated with E. coli bacteria than boreholes (p=6.2x10-6), suggesting non-consideration of local hydrogeologic factors in groundwater development. Water from boreholes that tested negative for pathogens at source tested positive at some households (total coliform: p=0.0042 and E. coli p=7.8x10-7) suggesting the effect of handling practices. Water from wells that was not treated with chlorine showed higher levels of E. coli than treated water from the same sources, confirming the effectiveness of chlorine in reducing pathogenic bacteria in households’ stored drinking-water, reinforcing the scientific basis for scaling up chlorine as effective disinfectant. However, this study demonstrated that chlorine failed to effectively eliminate all pathogens in drinking water. As a case study in tropical rural environments in Africa, these findings on the suitability of using chlorine as disinfectant and on factors explaining groundwater contamination, though provisional, provide a scientific basis for assessing cost-effectiveness and sustainability of scaling-up the use of chlorine as a curative remedy and of systematically investigating local hydrogeologic factors in order to implement measures to protect groundwater quality in poverty-prone rural communities.

This paper deals with alternative hosts of an egg parasitoid. Trichogramma dendrolimi Matsumura in three habitats: mixed forest, pure stand and sparse wood. The experiment was conducted in Liuyan County which is located in the eastern part of Hunan Province. The results suggested that there are 103 species of alternative Lepidopteran hosts for T. dendrolimi. There were two critical periods throughout the year when there were no eggs of Dendrolimus punctatus Walker and few eggs of alternative hosts available for ovipsition by the parasitoids.

This paper provides an integrated approach to the analysis of the geological, hydrological and hydrogeological characteristics of the Cape Flats: a coastal plain sand formed within the mountains of the Cape Town metropolitan area. The study is mainly based on evaluation of available data, on surface water and groundwater, rainfall and selected springs, to describe the Cape Flats aquifer. Qualitative analysis has shown that both surface water and groundwater of the investigated area are of good quality; whereas sources of contamination indicated are restricted to certain parts of the area. Interpretation of hydrogeological data and aquifer parameters revealed that the Cape Flats aquifer has good storage characteristics to support its development for water supply, although the generally unconfined conditions render it highly susceptible to pollution from the surface. From the analysis of long-term climate data in Cape Town, it is evident that fluctuation exists in the pattern ofrainfall; this rainfall pattern has implications for recharge and water management issues in the city. Therefore, a conceptual hydrogeological model was developed to elucidate groundwater flow and recharge mechanisms in the Cape Flats.Keywords: water resource management, Cape Town, water quality, surface-water/groundwater relations, conceptualisation

I - Best practice guidelines 1 Water supply and sanitation issues in Africa *1.1 Contribution of water supply and sanitation to African development *1.2 Millennium development goals and water *1.3 Water supply and sanitation coverage *1.4 Challenges and strategies to achieve the MDGs for WSS *1.4.1 Rural water supply *1.4.2 Urban water supply *1.4.3 Sanitation *1.4.4 General *1.5 Various programmes to achieve goal *1.6 From water for domestic use to a livelihoods focus *1.7 Conclusions 2 Groundwater resources in Africa *2.1 Characteristics of groundwater resources *2.1.1 Major types of aquifers *2.1.2 Groundwater resources in Africa *2.1.3 Roles and functions *2.2 The sustainable groundwater utilization and management in Africa *2.2.1 Major groundwater-related issues and problems on the African continent *2.2.2 The data and information management relating to groundwater resources management *2.2.3 Implication of climate change *2.3 Outlook for the sustainable utilization of groundwater in Africa 3 Framework of best practices for groundwater supply and sanitation provision *3.1 Introduction *3.2 Integrated water resources management *3.3 Groundwater and IWRM *3.4 Integrated water, sanitation and hygiene delivery *3.5 Integrated service delivery in the urban environment *3.6 Integrated service delivery in the rural environment *3.7 A framework to facilitate groundwater management 4 Best practice for groundwater quality protection *4.1 General introduction *4.2 South African borehole guidelines *4.2.1 Introduction *4.2.2 Relevant literature *4.2.3 Contracts and agreements *4.2.4 Supervision of activities *4.2.5 Materials and equipment *4.2.6 Aanomalous circumstances *4.2.7 Straightness and verticality *4.2.8 Protecting the resources *4.2.9 Safety *4.2.10 Conclusions *4.3 Groundwater protection guidelines *4.3.1 Basic approaches *4.3.2 Concept of safe distance *4.3.3 Stepwise procedure from case studies *4.3.4 Zoning approach *4.3.5 Protection approach in fractured rock aquifers *4.3.6 Spring and shallow well protection *4.4 Drought proofing *4.4.1 Basic concepts *4.4.2 Types of drought *4.4.3 Livelihood approach *4.5 On-site sanitation and groundwater *4.6 Ecosan approach for effective groundwater resources management *4.6.1 Historical context of Ecosan *4.6.2 Main objective of Ecosan projects *4.6.3 The philosophy about Ecosan *4.6.4 Ecosan and groundwater quality *4.6.5 The challenge for Ecosan *4.7 Community participation best practice *4.8 Towards a comprehensive approach 5 Summary and recommendations *5.1 Summary *5.2 Recommendations II - Case studies 6 Groundwater dynamics in the East African Rift System *6.1 Introduction *6.2 Tectonic framework *6.3 Hydrology and climate *6.4 Hydrogeological framework *6.5 Hydrogeochemical feature *6.6 Implication on water supply and sanitation *6.7 Summary and recommendations 7 Aquifer vulnerability and its implication for community water supply of Porto-Novo region (South - East of Benin) *7.1 Introduction *7.2 Site description *7.3 Data requirements *7.3.1 DRASTIC and GOD methods *7.3.2 Evaluation of DRASTIC and GOD parameters *7.3.3 Validation of vunerability maps and determination of aquifer protection *7.4 Results and discussion *7.4.1 Vulnerability maps *7.4.2 Discussion *7.5 Conclusion 8 Vulnerability of dolomite aquifers in South Africa *8.1 Introduction *8.2 Geological description *8.3 Methodology *8.3.1 Overlying layers map (O-Map) *8.3.2 Concentration of flow map (C-Map) *8.3.3 Precipitation map (P-Map) *8.4 VUKA index map *8.5 Summary 9 A low tech approach to evaluating vulnerability to pollution of basement aquifers in sub-saharan aquifer *9.1 Introduction *9.2 The weathered basement aquifer *9.3 The groundwater vulnerability drivers *9.4 Simple field approach to vulnerability assessment *9.5 Scorecard validity *9.6 Conclusions 10 Preserving groundwater quality against microbiological contamination through differentiated aquifer management in Africa *10.1 Introduction *10.2 Microbiological transport within secondary aquifers *10.3 Extent of microbiological impacts on some africa aquifers *10.4 State of microbiological monitoring networks in Africa *10.5 Groundwater protection zoning *10.6 Way forward *10.7 Conclusion 11 Fluoride in African groundwater: Occurrence and mitigation *11.1 Introduction *11.2 Sources of fluoride in groundwater *11.3 Formation of fluoride-rich groundwater *11.4 Determination of fluoride *11.5 Fluoride occurrence in African groundwater *11.6 Removal of fluoride from drinking water supplies *11.7 Alternative mitigation *11.8 Implication for rural water supplies 12 Practical methods to reduce iron in groundwater with a case study *12.1 Introduction *12.2 Project area *12.3 Methodology *12.4 Iron removal *12.5 Results *12.6 Iron filter construction *12.7 Conclusion 13 Investigation of borehole failures - experience from Botswana *13.1 Introduction *13.2 Hydrogeology of the study area *13.3 Methodology and data uesd *13.3.1 Methodology *13.3.2 Data used *13.4 Results and discussion *13.4.1 Evidence of possible recent decline in groundwater yield *13.4.2 Correlation analysis *13.4.3 Reliability analysis of groundwater monitoring data *13.5 Summary, conclusion and recommendation 14 Cost-effective boreholes in sub-saharan Africa *14.1 Introduction *14.2 Assertions, information and evidence of high drilling prices *14.3 Conceptual framework *14.3.1 Borehole costs and quality *14.3.2 Borehole price *14.3.3 The core factors *14.3.4 Key elements *14.4 Analysis of the thirteen elements of cost-effective boreholes *14.4.1 Operation and maintenance procedures *14.4.2 Who drills water wells? *14.4.3 Borehole standards and designs *14.4.4 Drilling equipment - smaller and less costly rigs *14.4.5 Procurement process *14.4.6 Contract packaging *14.4.7 Contract packaging *14.4.8 Siting practices *14.4.9 Supervision *14.4.10 Pumping test *14.4.11 Groundwater resources monitoring and evaluation *14.4.12 Hydrogeological data *14.4.13 Regulation and professionalism of the private sector *14.5 Conclusions and recommendations 15 Water supply and sanitation in the democratic republic of the Congo *15.1 Introduction *15.2 Overview of the study area *15.2.1 Location and climate *15.2.2 Geology and tectonics *15.2.3 Soils and land use *15.2.4 Hydrography *15.3 Socio-demography *15.4 Water resources *15.4.1 Surface water resources *15.4.2 Groundwater resources *15.5 Water supply *15.5.1 Water supply sources and access to drinking water *15.6 Sanitation *15.6.1 Current situation in the DRC *15.6.2 Water and health issues *15.6.3 Financial requirements *15.7 Institutions and legislation *15.7.1 Laws and regulations *15.7.2 Institutions *15.8 Government policies and strategies to improve WatSan sector *15.9 Constraints to the WatSan developent In DRC *15.10 WatSan donors *15.11 Conclusion 16 Rural water supply and sanitation in Malawi: Groundwater context *16.1 Introduction *16.2 Study area charaterization *16.3 Methods *16.4 Results and discussions *16.4.1 Water sources and water point coverage *16.4.2 Functionality status of rural water points *16.4.3 Groundwater availability and its associated quality pattern *16.4.4 Water quality monitoring *16.4.5 Current sanitation service provision *16.4.6 Current initiatives within the rural water supply and sanitation sub-sector *16.5 Conclusions 17 Community-based groundwater quality monitoring: A field example *17.1 Introduction *17.2 Background *17.3 Methods *17.4 Results from the Initial Implementation *17.5 Analysis of the Initial Implementation *17.6 Brief comparison with another recent study on use of simple measures *17.7 Conclusions 18 Charitable endowments as an institute for sustainable groundwater development and management *18.1 Introduction *18.2 Practice in the Middle East *18.3 Socio economic issues *18.4 Technical issues *18.5 Conclusion Subject index Colour plate