Recharge Discharge Research Articles

Convective Coupling in Tropical-Depression-Type Waves. Part II: Moisture and Moist Static Energy Budgets

AbstractThe companion of this paper, Part I, discovered the characteristics of the rainfall progression in tropical-depression (TD)-type waves over the western North Pacific. In Part II, the large-scale controls on the convective rainfall progression have been investigated using the ERA-Interim data and the TRMM 3B42 precipitation-rate data during June–October from 1998 to 2013 through budgets of moist static energy (MSE) and moisture. A buildup of column-integrated MSE occurs in advance of deep convection, and an export of MSE occurs following deep convection, which is consistent with the MSE recharge–discharge paradigm. The MSE recharge–discharge is controlled by horizontal processes, whereby horizontal moisture advection causes net MSE import prior to deep convection. Such moistening by horizontal advection creates a moist midtroposphere, which helps destabilize the atmospheric column, leading to the development of deep convective rainfall. Following the heaviest rainfall, negative horizontal moisture advection dries the troposphere, inhibiting convection. Such moistening and drying processes explain why deep convection can develop without preceding shallow convection. The advection of moisture anomalies by the mean horizontal flow controls the tropospheric moistening and drying processes. As the TD-type waves propagate northwestward in coincidence with the northwestward environmental flow, the moisture, or convective rainfall, is phase locked to the waves. The critical role of the MSE import by horizontal advection in modulating the rainfall progression is supported by the anomalous gross moist stability (AGMS), where the lowest AGMS corresponds to the quickest increase in the precipitation rate prior to the rainfall maximum.

Wetlands in the Athabasca Oil Sands Region: the nexus between wetland hydrological function and resource extraction

Oil sands development within the Athabasca Oil Sands Region (AOSR) has accelerated in recent decades, causing alteration to natural ecosystems including wetlands that perform many vital ecosystem functions such as water and carbon storage. These wetlands comprise more than half of the landscape, and their distribution and local hydrology are the result of interactions among a subhumid climate, topography, and spatially heterogeneous surficial and bedrock geology. Since hydrology plays a fundamental role in wetland ecological functioning and determines wetland sensitivity to human disturbances, the characterization of anthropogenic impacts on wetland hydrology in the AOSR is necessary to assess wetland resilience and to improve current best management practices. As such, this paper reviews the impacts of oil sands development and related disturbances including infrastructure construction, gravel extraction, and land clearing on wetland function in the AOSR. Hydrologic disturbances in wetlands in the AOSR include changes to soil hydrophysical properties that control water table position, the interruption of recharge–discharge patterns, and alteration of micrometeorological conditions; these in turn govern wetland ecological structure and wetland ecosystem processes (e.g., evapotranspiration, nutrient cycling). Given that anthropogenic disturbance can affect natural wetland succession, long-term hydrological monitoring is crucial for predicting the response of these ecosystems to varying levels of human impact.

Evaluation of mechanical properties of fluoride-releasing dental materials after multiple fluoride recharge/discharge application

This study aimed to determine the mechanical properties of fluoride-releasing dental materials after an accelerated fluoride recharge/discharge procedure. Two fluoride-releasing glass ionomer types of cement (Ketac Molar Easymix and IonoStar Molar), a resin-modified glass ionomer (Photac Fil Quick Aplicap), and two compomers (Compoglass F and Glasiosite) were used in this study. A total of 30 rectangular specimens and 30 disk specimens of each material were prepared and placed in distilled/deionized water (n = 5). The amount of fluoride released was analyzed from the materials for 7-day discharge, 1st recharge, 7-day discharge, 2nd recharge, and 7-day discharge, and 3rd recharge. The de/pre- and post-recharge fluoride release were measured using an ion chromatography for 24 days. The flexural strength and microhardness of each group were evaluated. The microhardness of all restorative materials showed no significant change (p > 0.05) over the experimental period. The flexural strength properties of the restorative materials did not change within the time of the study. The study showed that the fluoride release/uptake causes no effect on the mechanical and physical properties of dental materials.

Introducing the recharge–discharge relationship to evaluate the recharge coefficient of karstic aquifers: thematic and indexing approaches

ABSTRACT Karst aquifers and springs are important with respect to their potential for supplying drinking water in regions suffering from water scarcity in Iran. Accordingly, it is essential to determine the recharge potential of the catchment and the regions with higher obtainability potential. This study provides a road map for the Sheshpeer catchment in southern Iran. A recharge potential (RP) map was produced from which a recharge index (RI) was computed for several selected springs in the catchment. Furthermore, the unit discharge (q) – defined as the average annual discharge for a given catchment area and unit rainfall depth for each spring – was calculated. The plot of q versus RI for the springs showed a linear positive relationship between the two variables (R 2 = 0.9). Applying the trend equation of this plot to the whole Sheshpeer karstic catchment reveals that its long-term recharge coefficient is 0.74.

Recharge–Discharge Relations of Groundwater in Volcanic Terrain of Semi-Humid Tropical Highlands of Ethiopia: The Case of Infranz Springs, in the Upper Blue Nile

The major springs in the Infranz catchment are a significant source of water for Bahir Dar City and nearby villages, while sustaining the Infranz River and the downstream wetlands. The aim of the research was to understand the hydrogeological conditions of these high-discharge springs and the recharge–discharge relations in the Infranz catchment. The Infranz catchment is covered by highly pervious and young quaternary volcanic rocks, consisting of blocky, fractured, and strongly vesicular scoriaceous basalt. At the surface, these rocks crop out as lineaments forming ridges, delimiting closed depressions in which water accumulates during the rainy season without causing surface runoff. Geology and geomorphology thus combine to produce very favorable conditions for groundwater recharge. Three groundwater recharge methods were applied to estimate groundwater recharge and the results were compared. Groundwater recharge was calculated to be 30% to 51% of rainfall. Rapid replenishment raises the groundwater level during the rainfall period, followed by a rapid decline during the dry season. Shallow local flow paths discharge at seasonal springs and streams, while more regional and deeper flow systems downstream sustain the high-discharge springs and perennial Infranz River. The uptake of 75% of spring water for the water supply of Bahir Dar City, local extraction for domestic and small-scale irrigation use from springs, rivers and hand-dug wells, encroaching farming, and overgrazing are exacerbating wetland degradation.

Hydrochemical changes and groundwater grouping data by multivariate statistical methods within one karst system: recharge–discharge zone (Eastern Serbia case study)

To define changes in hydrochemical composition from the recharge to the discharge zone of the complex Kucaj–Beljanica karst massif, located in eastern Serbia, on a quarterly basis within one hydrologic year, a physico-chemical analysis was performed, along with the determination of ions (cations and anions) and isotope 13C content in rainwater, surface and groundwater (cold, sub-thermal and thermal). The multiparameter analysis of parameters was also used to determine the best combination and grouping of similar hydrochemical characteristics, as well as to determine the dependence of chemical parameters of the water, which may indicate the predominant complex geochemical underground processes. The results showed that the Ca2+ and dissolved oxygen O2 content in water decreases with circulation depth; while, the content of all other observed elements increases as a result of complex geochemical processes that occur within the complex karst environment.

Effects of Tropical Cyclones on ENSO

AbstractNumerous studies have investigated the role of El Niño–Southern Oscillation (ENSO) in modulating the activity of tropical cyclones (TCs) in the western Pacific on interannual time scales, but the effects of TCs on ENSO are less discussed. Some studies have found that TCs sharply increase surface westerly anomalies over the equatorial western–central Pacific and maintain them there for a few days. Given the strong influence of equatorial surface westerly wind bursts on ENSO, as confirmed by much recent literature, the effects of TCs on ENSO may be much greater than previously expected. Using recently released observations and reanalysis datasets, it is found that the majority of near-equatorial TCs (simply TCs hereafter) are associated with strong westerly anomalies at the equator, and the number and longitude of TCs are significantly correlated with ENSO strength. When TC-related wind stresses are added into an intermediate coupled model, the simulated ENSO becomes more irregular, and both ENSO magnitude and skewness approach those of observations, as compared with simulations without TCs. Adding TCs into the model system does not break the linkage between the heat content anomaly and subsequent ENSO event in the model, which manifest the classic recharge–discharge ENSO dynamics. However, the influence of TCs on ENSO is so strong that ENSO magnitude and sometimes its final state—that is, either El Niño or La Niña—largely depend on the number and timing of TCs during the event year. Our findings suggest that TCs play a prominent role in ENSO dynamics, and their effects must be considered in ENSO forecast models.

Comparative study of mineral and surface waters of Araxá spa, Minas Gerais State, Brazil

The natural mineral waters of the springs Dona Beja (DBS) and Andrade Junior (AJS) from Araxa city, in the Brazilian State of Minas Gerais (MG), are well known since the nineteenth century when started the studies of their healing properties for the tuberculosis treatment. In Brazil, the period 1930–1950 corresponded to the construction peak of thermal and non-thermal spas for therapeutic and leisure purposes. In 1944, the President Getulio Vargas inaugurated a large spa at Barreiro area in Araxa city. The DBS waters have low salinity, high radioactivity, discharge sustained by the recharging rainwater, and expected low residence time in the aquifer due to the maximum recharge–discharge distance of 2–3 km. The AJS waters are hypothermal/thermal, alkaline, sulfured, highly saline, exhibiting deep circulation and discharging in a site dominated by slightly weathered rocks. Barreiro area is also characterized by the exploration of phosphate fertilizer (begun in 1947–1948) and niobium (identified in pyrochlore in 1953). Since the 60s and 70s, the demand for these resources increased, favoring the release of contaminants into the environment. As a consequence, several professionals and institutions belonging to different sectors of the society have pointed out potential environmental problems due to possible contamination of the DBS and AJS waters, with implications for reducing the tourism activities in the region that take an important role on the municipality economy. This study compared the major hydrochemical characteristics of the DBS and AJS waters with those of other surface waters and rainwater occurring in that area for identifying possible degradation of their quality due to the anthropogenic inputs taking place there.

The effects of confinement on TiO2@SnO2@TiO2 hollow spheres for high reversible lithium storage capacity

In this study, we synthesize TiO2@SnO2@TiO2 hollow spheres, in which a tin dioxide (SnO2) layer was encapsulated in double-shell titanium dioxide (TiO2) hollow spheres (the spheres are denoted TST) through biomimetic layer-by-layer mineralization combined with etching of the template SiO2. When used as the anode material for lithium ion batteries, TST displayed average rechargeable discharge capacities of 426, 328, 272, 231, 174 and 118 mAh/g at 100, 200, 400, 800, 1600 and 3200 mA/g, respectively. The uniform TST retained a discharge capacity of 286 mAh/g after 500 cycles at a high rate of 800 mA/g, which is superior to that of control SnO2@TiO2 hollow spheres. The good performance of TST is attributed to the following reasons. First, the unique structure of TST consisted of a SnO2 layer sandwiched between two TiO2 layers; the confinement effect of the TiO2 shells are proposed to mitigate the volume change of SnO2 during lithium insertion/extraction. Second, the composites combine the advantages of the high capacity of SnO2 and structural stability of TiO2. Spatial confinement between the double TiO2 shells may play an important role in enhancing the lithium storage reaction of TST.

A review of ENSO theories

Abstract The El Niño and the Southern Oscillation (ENSO) occurrence can be usually explained by two views of (i) a self-sustained oscillatory mode and (ii) a stable mode interacting with high-frequency forcing such as westerly wind bursts and Madden-Julian Oscillation events. The positive ocean–atmosphere feedback in the tropical Pacific hypothesized by Bjerknes leads the ENSO event to a mature phase. After ENSO event matures, negative feedbacks are needed to cease the ENSO anomaly growth. Four negative feedbacks have been proposed: (i) reflected Kelvin waves at the ocean western boundary, (ii) a discharge process due to Sverdrup transport, (iii) western-Pacific wind-forced Kelvin waves and (iv) anomalous zonal advections and wave reflection at the ocean eastern boundary. These four ENSO mechanisms are respectively called the delayed oscillator, the recharge–discharge oscillator, the western-Pacific oscillator and the advective–reflective oscillator. The unified oscillator is developed by including all ENSO mechanisms, i.e. all four ENSO oscillators are special cases of the unified oscillator. The tropical Pacific Ocean and atmosphere interaction can also induce coupled slow westward- and eastward-propagating modes. An advantage of the coupled slow modes is that they can be used to explain the propagating property of interannual anomalies, whereas the oscillatory modes produce a standing oscillation. The research community has recently paid attention to different types of ENSO events by focusing on the central-Pacific El Niño. All of the ENSO mechanisms may work for the central-Pacific El Niño events, with an addition that the central-Pacific El Niño may be related to forcing or processes in the extra-tropical Pacific.

Combined Role of High- and Low-Frequency Processes of Equatorial Zonal Transport in Terminating an ENSO Event

This study investigates the sudden reversal of anomalous zonal equatorial transport above thermocline at the peak phase of ENSO. The oceanic processes associated with zonal transport are separated into low-frequency ENSO cycle and high-frequency oceanic wave processes. Both processes can generate a reversal of equatorial zonal current at the ENSO peak phase, which is a trigger for the rapid termination of ENSO events. For the low-frequency process, zonal transport exhibits slower and basinwide evolution. During the developing phase of El Niño (La Niña), eastward (westward) transport prevails in the central-eastern Pacific, which enhances ENSO. At the peak of ENSO, a basinwide reversal of the zonal transport resulting from the recharge–discharge process occurs and weakens the existing SST anomalies. High-frequency zonal transport presents clear eastward propagation related to Kelvin wave propagation at the equator, reflection at the eastern boundary, and the westward propagating Rossby waves. The major westerly wind bursts (easterly wind surges) occur in late boreal summer and fall with coincident downwelling (upwelling) Kelvin waves for El Niño (La Niña) events. After the peak of El Niño (La Niña), Kelvin waves reach the eastern boundary in boreal winter and reflect as off-equatorial Rossby waves; then, the zonal transport switches from eastward (westward) to westward (eastward). The high-frequency zonal transport can be represented by equatorial wave dynamics captured by the first three EOFs based on the high-pass-filtered equatorial thermocline. The transport anomaly during the decaying phase is dominated by the low-frequency process in El Niño. However, the transport anomaly is caused by both low- and high-frequency processes during La Niña.

Multivariate Analysis of Water Quality of the Chenqi Basin, Inner Mongolia, China

Numerous water samples are necessary to predict and assess water quality. However, if the geographical conditions surrounding mines are harsh mountainous areas, continuous or uniform sampling can be challenging, resulting in difficult sampling or data loss. In this study, statistical analysis of normalized data collected in the Chenqi Basin, including factor analysis and principal component analysis, revealed the water quality’s macro-distribution. Analytic solutions of partial differential equations of regional phreatic water quality were used to evaluate the mining and recharge–discharge of the regional phreatic aquifer. This method compensates for the disadvantage of evaluating discrete samples. Hydrogeological monitoring, pumping tests, and water quality analysis of phreatic water were carried out in the west of the Dongming open pit mine. Eight hydrogeochemical water quality variables (WQV) were selected as analysis targets. With hydrogeological generalization, regression equations of the diffusion of WQV and the seepage field were developed by a cumulative index that samples data from different orientations. One-dimensional diffusion partial differential equations of WQV, which are related to the distance and time of the seepage flow, were derived. Current and future predictions and evaluations of the phreatic water quality in the basin were made by ArcGIS based on regression and cumulative evaluation index methods. Findings revealed that the influence area of the mine would significantly expand in 10 years if current conditions continue. In addition, the diffusion speed was found to be higher in the southwestern part of the mine than in the west and northwestern parts, which is consistent with the recharge and discharge conditions of the Chenqi Basin.

A theoretical model of strong and moderate El Niño regimes

The existence of two regimes for El Nino (EN) events, moderate and strong, has been previously shown in the GFDL CM2.1 climate model and also suggested in observations. The two regimes have been proposed to originate from the nonlinearity in the Bjerknes feedback, associated with a threshold in sea surface temperature ( $$T_c$$ ) that needs to be exceeded for deep atmospheric convection to occur in the eastern Pacific. However, although the recent 2015–16 EN event provides a new data point consistent with the sparse strong EN regime, it is not enough to statistically reject the null hypothesis of a unimodal distribution based on observations alone. Nevertheless, we consider the possibility suggestive enough to explore it with a simple theoretical model based on the nonlinear Bjerknes feedback. In this study, we implemented this nonlinear mechanism in the recharge-discharge (RD) ENSO model and show that it is sufficient to produce the two EN regimes, i.e. a bimodal distribution in peak surface temperature (T) during EN events. The only modification introduced to the original RD model is that the net damping is suppressed when T exceeds $$T_c$$ , resulting in a weak nonlinearity in the system. Due to the damping, the model is globally stable and it requires stochastic forcing to maintain the variability. The sustained low-frequency component of the stochastic forcing plays a key role for the onset of strong EN events (i.e. for $$T>T_c$$ ), at least as important as the precursor positive heat content anomaly (h). High-frequency forcing helps some EN events to exceed $$T_c$$ , increasing the number of strong events, but the rectification effect is small and the overall number of EN events is little affected by this forcing. Using the Fokker–Planck equation, we show how the bimodal probability distribution of EN events arises from the nonlinear Bjerknes feedback and also propose that the increase in the net feedback with increasing T is a necessary condition for bimodality in the RD model. We also show that the damping strength determines both the adjustment time-scale and equilibrium value of the ensemble spread associated with the stochastic forcing.

Oceanic processes of upper ocean heat content associated with two types of ENSO

The spatiotemporal variability of equatorial Pacific upper ocean heat content (HC) and subsurface heat during two types of El Nino-Southern Oscillation (ENSO), namely eastern and central Pacific (EP and CP) types, is investigated using subsurface ocean heat budget analysis. Results show that HC tendencies during both types of ENSO are mainly controlled by oceanic heat advection beneath the mixed layer to the thermocline, and the role of net surface heat flux can be neglected. The most important three terms are the zonal and vertical advections of anomalous heat by climatological currents (QU 0 T′, QW 0 T′) and zonal advection of climatological heat by anomalous current (QU′T 0). The large contribution of QU 0 T′ extends from west to east along the equatorial Pacific. The considerable contribution of QU′T 0 is confined to the east of 160°W, and that of the QW 0 T′ is observed in the central Pacific between 180°E and 120°W. In particular, a major contribution of QW 0 T′ is also observed in the far eastern Pacific east of 100°W during EP ENSO. There is also a small contribution from meridional advection of climatological heat by anomalous current (QV′T 0). In contrast, the meridional advection of anomalous heat by climatological currents (QV 0 T′) and vertical advection of climatological heat by anomalous current (QW′T 0) are two damping factors in the HC tendency, with the former dominating. Differences in spatial distribution of the heat advection associated with the two types of ENSO are also presented. We define a warm water heat index (WWH) as integrated heat content above 26 kg m−3 potential density (26σ ɵ ) isopycnal depth within 130°E–80°W and 5°S–5°N. Further examination suggests that the recharge–discharge of WWH is involved in both types of El Nino, though with some differences. First, it takes about 42 (55) months for the evolution of a recharge–discharge cycle during an EP (CP) ENSO. Second, the EP El Nino event peaks during the discharge phase, 7–8 months after the recharge time. The CP El Nino peaks during the recharge phase, 4–5 months before the recharge time. The locations of HC anomalies in the El Nino mature phase relative to those at recharged time explain why the EP and CP El Nino peak in different stages of the recharge–discharge process.

Geostatistical and geochemical model-assisted hydrogeochemical pattern recognition along the groundwater flow paths in Coimbatore district, South India

The deterioration of groundwater quality in Coimbatore district is principally attributed to the geological formations, application of agrochemicals and discharge of untreated industrial effluents. Groundwater samples were collected and analysed to obtain the hydrochemical characteristics for delineating the groundwater recharge and discharge zones. Alkaline water is present in the district during all seasons. Groundwater facies were evaluated and the majority of them were CaHCO3 and Ca–Na–HCO3 types. Generally, HCO3 was used to identify the recharge area and Cl the discharge area. Dominance of HCO3 in both water types helps in identifying the recharge zones. The TDS and major ions in conjunction with HCO3/Cl, SO4/HCO3, HCO3 + CO3/Ca + Mg, HCO3 + CO3/T.anions and Cl/T.anions were used in the delineation of recharge–discharge areas. Results of geochemical modelling using PHREEQC were in agreement with the analysis of ionic ratios. Carbonate minerals are saturated in the recharge zone and become undersaturated as the flow progresses. HCO3 to Cl types for the recharge to discharge zones were confirmed by the aqueous speciation modelling. Gradual increase of NO3 along the flow path also supported the increasing anthropogenic influences towards the discharge zone. The spatial distribution diagrams drawn for each of these ratios suggested that a major part of the study area is covered by recharge zones. Mettupalayam and Pollachi taluks were found to be discharge zones. The results of the study showed that the water quality in the discharge zones is largely controlled by anthropogenic activities. The study gains importance since part of the water supply to the Coimbatore corporation area is from a source in the neighbouring state and the major surface water source of this area comes under an interstate water dispute.

Development of energy-saving technology to support functioning of the lead-acid batteries

Based on mathematical and logical modeling, a technological support system for changing the battery capacity based on the prediction of voltage variation in measuring the temperature of electrolyte in the volume of the batteries was developed in the com-position of a technological system for battery operation. The developed technology makes it possible: to control operational capacity of the accumulator battery in order to obtain a functional assessment of change in the total charge and discharge voltage; to obtain an integrated reference estimation of change in the charge and discharge volt-age; to develop an integrated system for assessing a change in the voltage of the battery, which enables maintaining capacity of the accumulator battery when measuring the temperature of electrolyte at the input to the battery. The limiting temperature change of electrolyte, – 35 °C, was determined at charging with direct current supply and a limit-ing voltage change for a further charge and discharge was established with a change in the consumption of electric energy. The use of an integrated system for the estimation of voltage change obtained based on the alignment between electrochemical and diffusion processes of discharge and charge makes it possible to take timely decisions on recharg-ing to prevent recharge and unacceptable discharge. Coordination of the electrochemi-cal and diffusion processes that accompany charging and discharging of the battery makes it possible, for example under conditions of functioning of a wind power plant with a capacity of 10 kW, to reduce the cost of production of energy and the payback period of the wind power plant by up to 25 % due to a reduction of the charge period and prevention of gas formation.

Identifying three-dimensional nested groundwater flow systems in a Tóthian basin

Abstract Nested groundwater flow systems have been revealed in Toth's theory as the structural property of basin-scale groundwater circulation but were only well known with two-dimensional (2D) profile models. The method of searching special streamlines across stagnation points for partitioning flow systems, which has been successfully applied in the 2D models, has never been implemented for three-dimensional (3D) Tothian basins because of the difficulty in solving the dual stream functions. Alternatively, a new method is developed to investigate 3D nested groundwater flow systems without determination of stagnation points. Connective indices are defined to quantify the connection between individual recharge and discharge zones along streamlines. Groundwater circulation cells (GWCCs) are identified according to the distribution of the connective indices and then grouped into local, intermediate and regional flow systems. This method requires existing solution of the flow velocity vector and is implemented via particle tracking technique. It is applied in a hypothetical 3D Tothian basin with an analytical solution of the flow field and in a real-world basin with a numerical modeling approach. Different spatial patterns of flow systems compared to 2D profile models are found. The outcrops boundaries of GWCCs on water table may significantly deviate from and are not parallel to the nearby water table divides. Topological network is proposed to represent the linked recharge–discharge zones through closed and open GWCCs. Sensitivity analysis indicates that the development of GWCCs depends on the basin geometry, hydraulic parameters and water table shape.

Comparative Prediction of Groundwater Fluctuation by CWTFT-ANFIS and WT-ANFIS

Objective: To evaluate the ability of prediction performance of ANFIS (Adaptive Neuro Fuzzy Inference System) model on groundwater level fluctuation in Lower Bhavani River Basin (LBRB). Method: To improve the accuracy of prediction of ANFIS model, WT (Wavelet Transform) and CWTFT (Continuous Wavelet Fast Fourier Transform) are performed as preprocessing techniques. Model development is carried out through three different input parameters (duration, groundwater recharge and groundwater discharge) and one output parameter (groundwater fluctuation) for the period of 2009-2015 on monthly stress basis. Findings: Based on the comparative prediction by the models CWTFT-ANFIS and WTANFIS over conventional ANFIS model through calibration and validation process on different reaches of the study area, optimum model is identified. Statistical indices are performed to measure the best fitting and trend identification for the each prediction.

Influence of Oceanic Intraseasonal Kelvin Waves on Eastern Pacific Hurricane Activity

Abstract Recent studies have highlighted the role of subsurface ocean dynamics in modulating eastern Pacific (EPac) hurricane activity on interannual time scales. In particular, the well-known El Niño–Southern Oscillation (ENSO) recharge–discharge mechanism has been suggested to provide a good understanding of the year-to-year variability of hurricane activity in this region. This paper investigates the influence of equatorial subsurface subannual and intraseasonal oceanic variability on tropical cyclone (TC) activity in the EPac. That is to say, it examines previously unexplored time scales, shorter than interannual, in an attempt to explain the variability not related to ENSO. Using ocean reanalysis products and TC best-track archive, the role of subannual and intraseasonal equatorial Kelvin waves (EKW) in modulating hurricane intensity in the EPac is examined. It is shown first that these planetary waves have a clear control on the subannual and intraseasonal variability of thermocline depth in the EPac cyclone-active region. This is found to affect ocean subsurface temperature, which in turn fuels hurricane intensification with a marked seasonal-phase locking. This mechanism of TC fueling, which explains up to 30% of the variability of TC activity unrelated to ENSO (around 15%–20% of the total variability), is embedded in the large-scale equatorial dynamics and therefore offers some predictability with lead time up to 3–4 months at seasonal and subseasonal time scales.

A New Method for Evaluating Riverside Well Locations Based on Allowable Withdrawal

This study aims to derive the optimal solution for well locations based on the allowable withdrawal. To demonstrate the proposed technique, a numerical model of a typical well field at the Qinbei Power Plant was constructed and 20 possible drawdown scenarios were simulated for each of three different arrangements of pumping wells. The concept of the Unit Increased Drawdown Value (UIDV) was used as a basis to select the location of pumping wells, where the UIDV is defined as the increase in drawdown associated with the addition of a unit of extraction. Results showed that for modeled well fields with the same number of wells and rates of exploitation, drawdown will reach the maximum and minimum when the well field is located in the recharge zone and discharge zone, respectively, because of the specific relationships between groundwater and surface water. This paper considered a pumping program with maximum exploitation and minimum costs corresponding to allowable withdrawals of 2.44 m3/s and 1.07 m3/s, respectively, and the relationship between groundwater and surface water was elucidated. The study results provide a theoretical basis for the layout of wells. The solution takes economic factors into consideration and describes the best solution for well locations to meet drawdown limitations during pumping applications.