DYNAMIC MODELS OF AQUIFEROUS CONTENT OF LIVING FUELS

Forest fire occurrence is closely relative with fuel water content. There are a lot of research about dead fuels. but forest fuels consist of both dead fuels and living fuels. Each large fire occurrence has a good relationship with living fuels. Especially living fuels can influence the production and development of big forest fire, so, we selected Tahe, in Daxingan Mountains, as observation site. According to actual data,we can establish a set of models of different living fuel water content variation with linear -regression method.

Groundwater Monitoring in the Gneisso-Basaltic Fractured Rock Aquiferous Formations of Kumba, Southwest Region Cameroon: Seasonal Variations in the Aqueous Geochemistry and Water Quality

The objective was to determine and monitor seasonal changes during four hydrological seasons: Wet season (September), Wetdry season (December), Dry season (March) and Drywet season (June) in the groundwater aqueous geochemistry and its domestic-agro-industrial quality using physicochemical parameters and hydrogeochemical tools: Temperature, Electrical Conductivity EC, pH, Total dissolved solids TDS, Ionic ratios, Gibbs diagrams, Piper diagrams Durov diagrams, total hardness HT, Water quality index WQI, Sodium adsorption ratio SAR, Percent Sodium %Na, Kelly’s Ratio KR, permeability index PI, Magnesium adsorption ratio MAR, Residual sodium carbonate RSC and Wilcox diagram. Field physicochemical parameters ranged from: Wet season;pH 3.9 - 6.9;Temperature, 23.3°C - 29.1°C;EC, 10 - 1900 μS/cm;TDS, 6.7 - 1273 mg/L;Wetdry, pH, 5.7 - 11.7;Temperature, 23.6°C - 28.3°C;EC, 1 - 1099 μS/cm, TDS, 0.67 - 736.33 mg/L;Dry pH, 5.7 - 13.1;Temperature, 26.3°C - 30.2°C;EC, 12 - 770 μS/cm, TDS, 8.04 - 515.9 mg/L and Drywet, pH, 4 - 7.4;Temperature, 25.8°C - 30.7°C;EC, 10 - 1220 μS/cm, TDS, 6.7 - 817.4 mg/L. Seventy-two groundwater samples, 18 per season were analysed. All ionic concentrations fell below acceptable World Health Organization guidelines in all seasons. The sequence of abundance of major ions are;Wet, Ca+ > Mg2+ > Na+ = K+ > NH4+, HCO3? > Cl? > NO3? > SO42? > HPO42?;Wetdry Ca+ > K+ > Mg2+ > Na+ > NH4+, HCO3? > Cl? > SO42? > NO3? > HPO42?;Dry Ca+ > K+ > Mg2+ > Na+ > NH4+, HCO3? > Cl?> NO3? > SO42? > HPO42?;Drywet NH4+ > Ca+ > K+ > Mg2+ > Na+;Cl? > HCO3? > NO3? > SO42? > HPO42?. Groundwater ionic content was due to rock weathering and ion exchange reactions. CaSO4 is the dominant water type in Wet and Wetdry seasons;followed by CaHCO3, Na + K-Cl Wet, CaSO4 and CaHCO3 Wetdry;MgCl Dry and Drywet followed by CaCl, CaHCO3 Dry and CaSO4, CaHCO3 Dry-Wet. The dominant hydrogeochemical facies are Ca-Mg-Cl-SO4 followed by Na-K-SO4 Wet and Ca-Mg-HCO3? in all other seasons. Ion exchange, Simple dissolution and uncommon dissolution are the processes determining groundwater character. The water quality indices;WQI, HT, SAR, %Na, KR, PI, MAR,RSC and Wilcox diagrams, indicate that groundwater in Kumba is 80% - 100% excellent during the Drywet &Wet seasons, 5% - 10% unsuitable during the Wetdry & Dry seasons for domestic use while being excellent-good for Agro-Industrial uses in all other seasons. Physicochemical parameters in some areas exceeded permissible limits for drinking. All hydrogeochemical parameters vary with seasons and these variations show the impact of annual cycles of seasonal changes on the aqueous geochemistry of groundwater in Kumba.

A 2D GIS Approach for Mapping Aquiferous Zones Using Remotely Sensed Data within Obubra, Southeast-Nigeria

Groundwater is vital to the sustenance and well-being of man-kind, although it is constantly under immense pressure. For this reason, there is need to develop an effective, reliable, scientific and sustainable means of delineating zones of groundwater occurrence and distribution with high precision in other to effectively explore for this resource. In this study, remote sensing (RS) and geographical information system (GIS) have been combined to develop thematic maps of the zones of groundwater occurrence and distribution based on variable factors such as;elevation, drainage, lineament, slope, lithology and soil. The analytical hierarchy procedure (AHP) was employed to classify and subsequently assign weight to each variable factor through weighted overlay analysis. Integration of these factors with their relative classes defined was used to produce a 2D-model for predicting surface aquifers mapped within Obubra. The study delineated three (3) surface aquifer zones representing groundwater potential zones. Zones representing high groundwater potential cover an area of approximately 331.94 Km2, accounting for 29.58% of the study area. The region that represents moderate to good groundwater occurrence and distribution covers an estimated area of approximately 648.42 Km2, occupying 57.78% of the study area. Zones with groundwater of low potential account for a total surface area of approximately 141.81 Km2 which is about 12.64% of the entire study area. Regions that show good to moderate and high groundwater potentials, have a wider distribution all across the study area except at the southernmost part. The study therefore shows that it is effective in delineating surface potential zones and hitherto a 2D surface aquifer model for groundwater exploration campaigns within Obubra and its environs.

Delineation of Shallow Stratigraphy and Aquifer Formation at Kahe Basin, Tanzania: Implication for Potential Aquiferous Formation

Electrical resistivity method was conducted at Kahe-Mtakuja basin aimed at appraising the potential of the basin as a source of groundwater by establishing shallow stratigraphy and delineating aquifer formations. A total of fifty-eight vertical electrical sounding data (VES) were acquired using Schlumberger array and the data were analyzed to obtain apparent resistivity and layer depth. The interpretation of resistivity data revealed three main geoelectric layers. The first layer has resistivity values ranging from 40 to 230 Ωm with thickness ranging from 0.4 to 2 m. The second layer has resistivity values in the range of 2 to 10 Ωm and thickness of 2 to 25 m. The third layer has slightly high resistivity values ranging from 10 to 60 Ωm and thickness in the range of 30 to 70 m. This layer is mainly dominated with sand. The resistivity cross-sections constructed from the interpretation of VES data indicate that the Kahe-Mtakuja basin has shallow stratigraphy consisting of 3 layers. The layers are composed mainly of top red soil, clay (sometime alternating with sand) and sand formation holding the groundwater. These findings are consistent with lithological logs of the borehole drilled near Kahe-Mtakuja that indicate two to five layers composed of alluvial deposits alternating with different lithological thicknesses. The high correlation between the VES results and borehole lithological logs near Kahe-Mtakuja suggests that the area is potential for aquiferous formation. Based on constructed stratigraphy, the aquifer formation of the basin is found in alluvial deposits composed of mainly sand. The potentiality of this area for aquiferous formation is vital for providing additional baseline data on the aquifer characteristics and will assist in reducing water scarce in the area.

Aquifer Test求群孔抽水试验水文地质参数

在水文地质条件复杂的地区,往往采用大型的群孔抽水试验充分揭露含水层特征,获取水文地质参数。用Aquifer Test软件求解水文地质参数,则方便实用、简捷高效,可快速输出拟合图形和求参结果。Aquifer Test提供了丰富的求参方案,求参必须结合当地当时的水文地质条件实际情况考虑,选择适合的方案和时空数据求取水文地质参数。

Assessment of groundwater quantity, quality, and associated health risk of the Tano river basin, Ghana

In the Tano River Basin,groundwater serves as a crucial resource;however,its quantity and quality with regard to trace elements and microbiological loadings remain poorly understood due to the lack of groundwater logs and limited water research.This study presents a comprehensive analysis of the Tano River Basin,focusing on three key objectives.First,it investigated the aquifer hydraulic parameters and the results showed significant spatial variations in borehole depths,yields,transmissivity,hydraulic conductivity,and specific capacity.Deeper boreholes were concentrated in the northeastern and southeastern zones,while geological formations,particu-larly the Apollonian Formation,exhibit a strong influence on borehole yields.The study identified areas with high transmissivity and hydraulic conductivity in the southern and eastern regions,suggesting good groundwater avail-ability and suitability for sustainable water supply.Sec-ondly,the research investigated the groundwater quality and observed that the majority of borehole samples fall within WHO(Guidelines for Drinking-water Quality,Environmental Health Criteria,Geneva,2011,2017.http://www.who.int)limit.However,some samples have pH levels below the standards,although the groundwater generally qualifies as freshwater.The study further explores hydrochemical facies and health risk assessment,highlighting the dominance of Ca–HCO3 water type.Trace element analysis reveals minimal health risks from most elements,with chromium(Cr)as the primary contributor to chronic health risk.Overall,this study has provided a key insights into the Tano River Basin’s hydrogeology and associated health risks.The outcome of this research has contributed to the broader understanding of hydrogeologi-cal dynamics and the importance of managing groundwater resources sustainably in complex geological environments.

Identifying flow regime in the aquifer of fractured rock system in Germi Chai Basin,Iran

Considering the importance of fractured rock aquifers in the hydrogeologic process,this research aimed to analyze the flow regime,internal degree of karstification,and estimate storage volume in fractured rock aquifers of the Germi Chai Basin in northwest Iran,which is attributed to its active tectonics,erosion,and the lithological diversity.Given the geological setting,the hypothesis is that this basin is characterized by a high degree of karstification and diffuse or intermediate flow regime leading to variation in discharge flow rate.The hydrodynamic and hadrochemical analysis was conducted on 9 well distributed springs across the basin from 2019 to 2020.The maximum flow rate in most of the springs appeared in the early wet season despite their different levels of fluctuations on the monthly discharge time series.Analyzing the spring recession curve form revealed an aquifer containing multiple micro-regimes withαrecession coefficients and a degree of karstification ranging between 0.001 to 0.06 and 0.55 to 2.61,respectively.These findings indicated a dominant diffuse and intermediate flow system resulting from the development of a high density of fractures in this area.The electrical conductivity of the spring changes inversely proportional to the change in flow discharge,indicating the reasonable hydrological response of the aquifer to rainfall events.Hydrograph analysis revealed that the delay time of spring discharge after rainfall events mostly varies between 10 to 30 days.The total dynamic storage volume of the spring for a given period(2019-2020)was estimated to be approximately 1324 million cubic meters reflecting the long-term drainage potential and high perdurability of dynamic storage.Estimating the maximum and minimum ratio revealed that the springs recharging system in Germi Chai Basin comes under the slow aquifers category.This finding provides valuable insight into the hydrogeological properties of fractured rock aquifers contributing to effective water management strategy.

Analysis of pressure response at an observation well against pressure build-up by early stage of CO_(2)geological storage project

To ensure a safe and stable CO_(2)storage,pressure responses at an observation well are expected to be an important and useful field monitoring item to estimate the CO_(2)storage behaviors and the aquifer parameters during and after injecting CO_(2),because it can detect whether the injected CO_(2)leaks to the ground surface or the bottom of the sea.In this study,pressure responses were simulated to present design factors such as well location and pressure transmitter of the observation well.Numerical simulations on the pressure response and the time-delay from pressure build-up after CO_(2)injection were conducted by considering aquifer parameters and distance from the CO_(2)injection well to an observation well.The measurement resolution of a pressure transmitter installed in the observation well was presented based on numerical simulation results of the pressure response against pressure build-up at the injection well and CO_(2)plume front propagations.Furthermore,the pressure response at an observation well was estimated by comparing the numerical simulation results with the curve of CO_(2)saturation and relative permeability.It was also suggested that the analytical solution can be used for the analysis of the pressure response tendency using pressure build-up and dimensionless parameters of hydraulic diffusivity.Thus,a criterion was established for selecting a pressure transducer installed at an observation well to monitor the pressure responses with sufficient accuracy and resolution,considering the distance from the injection well and the pressure build-up at the injection well,for future carbon capture and storage(CCS)projects.

Thermo-hydro-mechanical (THM) coupled simulation of the land subsidence due to aquifer thermal energy storage (ATES) system in soft soils

Aquifer thermal energy storage(ATES)system has received attention for heating or cooling buildings.However,it is well known that land subsidence becomes a major environmental concern for ATES projects.Yet,the effect of temperature on land subsidence has received practically no attention in the past.This paper presents a thermo-hydro-mechanical(THM)coupled numerical study on an ATES system in Shanghai,China.Four water wells were installed for seasonal heating and cooling of an agriculture greenhouse.The target aquifer at a depth of 74e104.5 m consisted of alternating layers of sand and silty sand and was covered with clay.Groundwater level,temperature,and land subsidence data from 2015 to 2017 were collected using field monitoring instruments.Constrained by data,we constructed a field scale three-dimensional(3D)model using TOUGH(Transport of Unsaturated Groundwater and Heat)and FLAC3D(Fast Lagrangian Analysis of Continua)equipped with a thermo-elastoplastic constitutive model.The effectiveness of the numerical model was validated by field data.The model was used to reproduce groundwater flow,heat transfer,and mechanical responses in porous media over three years and capture the thermo-and pressure-induced land subsidence.The results show that the maximum thermoinduced land subsidence accounts for about 60%of the total subsidence.The thermo-induced subsidence is slightly greater in winter than that in summer,and more pronounced near the cold well area than the hot well area.This study provides some valuable guidelines for controlling land subsidence caused by ATES systems installed in soft soils.

Potential evaluation of saline aquifers for the geological storage of carbon dioxide: A case study of saline aquifers in the Qian-5 member in northeastern Ordos Basin

The well-developed coal electricity generation and coal chemical industries have led to huge carbon dioxide(CO_(2))emissions in the northeastern Ordos Basin.The geological storage of CO_(2) in saline aquifers is an effective backup way to achieve carbon neutrality.In this case,the potential of saline aquifers for CO_(2) storage serves as a critical basis for subsequent geological storage project.This study calculated the technical control capacities of CO_(2) of the saline aquifers in the fifth member of the Shiqianfeng Formation(the Qian-5 member)based on the statistical analysis of the logging and the drilling and core data from more than 200 wells in the northeastern Ordos Basin,as well as the sedimentary facies,formation lithology,and saline aquifer development patterns of the Qian-5 member.The results show that(1)the reservoirs of saline aquifers in the Qian-5 member,which comprise distributary channel sand bodies of deltaic plains,feature low porosities and permeabilities;(2)The study area hosts three NNE-directed saline aquifer zones,where saline aquifers generally have a single-layer thickness of 3‒8 m and a cumulative thickness of 8‒24 m;(3)The saline aquifers of the Qian-5 member have a total technical control capacity of CO_(2) of 119.25×10^(6) t.With the largest scale and the highest technical control capacity(accounting for 61%of the total technical control capacity),the Jinjie-Yulin saline aquifer zone is an important prospect area for the geological storage of CO_(2) in the saline aquifers of the Qian-5 member in the study area.

Developing three-dimensional groundwater flow modeling for the Erbil Basin using Groundwater Modeling System (GMS)

This study presents the development of a comprehensive three-dimensional groundwater flow model for the Erbil Basin utilizing the Groundwater Modeling System(GMS).The Erbil Basin,situated in the Kurdistan Region of Iraq,is a vital water resource area facing increasing water demands and environ-mental challenges.The three-dimensional nature of the groundwater flow system is crucial for accurately understanding and managing water resources in the basin.The modeling process involved data collection,geological and hydrogeological characterization,conceptual model development,and numerical simulation using GMS software MODFLOW 2000 package.Various parameters such as hydraulic conductivity,recharge rates,and boundary conditions were integrated into the model to represent the complex hydrogeo-logical conditions of the basin.Model calibration was performed by comparing simulated groundwater levels with observed data from monitoring wells across the basin,using the automatic calibration method of automated Parameter Estimation(PEST).Pilot points were applied to adjust the hydraulic conductivity in the model area spatially.Sensitivity analysis was conducted to assess the influence of key parameters on model predictions and to identify areas of uncertainty.The developed three-dimensional groundwater flow model provides valuable insights into the dynamics of groundwater flow,recharge-discharge mechanisms,and potential impacts of future scenarios such as climate change and water resource management strategies.It serves as a useful tool for decision-makers,water resource managers,and researchers to evaluate differ-ent management scenarios and formulate sustainable groundwater management policies for the Erbil Basin.In conclusion,this study demonstrates the effectiveness of using GMS for developing three-dimensional groundwater flow models in complex hydrogeological settings like the Erbil Basin,contributing to improved understanding and management of groundwater resources in the region.

Assessment of groundwater suitability for different activities in Toshka district,south Egypt

Globally,groundwater has globally emerged as a crucial freshwater source for domestic,irrigation,and industrial needs.The evaluation of groundwater quality in the Toshka region is imperative to ensure its suitability for the extensive agricultural and industrial activities underway in this promising,groundwater-dependent development area.This is particularly significant as Egypt increasingly relies on groundwater reserves to address freshwater deficits and to implement mega-development projects in barren lands.In this study,fifty-two samples were collected from the recently drilled wells tapping into the Nubian Sandstone Aquifer(NSA)in the Toshka region.Groundwater quality was assessed through hydrochemical analysis,Piper diagram,and various indicators such as Na%,SAR,RSC,KR,MH and PI.The hydrochemical analysis revealed improved groundwater quality characteristics,attributed to continuous recharge from Lake Nasser.The Piper diagram categorised most of the water samples as"secondary salinity"water type.Almost all wells proved suitable for irrigation with only two wells unsuitable based on MH values and six wells based on KR values.Considering Total Hardness(TH)values,all samples were classified as"Soft",indicating their suitability for domestic and industrial purposes.Water Quality Index(WQI)results concluded that all samples met WHO and FAO guidelines for drinking and irrigation,respectively.Spatial distribution maps,constructed using GIS,facilitate the interpretation of the results.Regular monitoring of quality parameters is essential to detect any deviation from permissible limits.

Development status and prospect of underground thermal energy storage technology

Underground Thermal Energy Storage(UTES)store unstable and non-continuous energy underground,releasing stable heat energy on demand.This effectively improve energy utilization and optimize energy allocation.As UTES technology advances,accommodating greater depth,higher temperature and multi-energy complementarity,new research challenges emerge.This paper comprehensively provides a systematic summary of the current research status of UTES.It categorized different types of UTES systems,analyzes the applicability of key technologies of UTES,and evaluate their economic and environmental benefits.Moreover,this paper identifies existing issues with UTES,such as injection blockage,wellbore scaling and corrosion,seepage and heat transfer in cracks,etc.It suggests deepening the research on blockage formation mechanism and plugging prevention technology,improving the study of anticorrosive materials and water treatment technology,and enhancing the investigation of reservoir fracture network characterization technology and seepage heat transfer.These recommendations serve as valuable references for promoting the high-quality development of UTES.

Hydrogeological and Physico-Chemical Study of the Groundwater of Mitendi South-East in the Commune of Mont-Ngafula around the Kimwenza Quarry (Province of Kinshasa, DR Congo)

The exploitation of groundwater by drilling in the Mitendi South-East district constitutes a solution to the water shortage in this peripheral part of the Mont-Ngafula township in Kinshasa, the capital of the DR Congo. Individuals exploit groundwater in boreholes to serve the population without taking into account certain necessary aspects such as the origin of the groundwater table and the quality which constitute the major problems of this work such as: What is the quantity of water from the recharge of our aquifer? What is the state of the Mitendi South-East aquifer water in relation to some physico-chemical parameters? The cardinal objective of this work is to provide chemical data and trace elements in each analyzed borehole and determine the type of recharge of the underground aquifer. The specific objectives are as follows: analyze the potability of groundwater on a physico-chemical level and their chemical facies, take the geographical coordinates of water samples from the aquifer in each targeted borehole in order to develop the sampling map of the area under study;also check each parameter analyzed in relation to WHO standards. We carried out a general investigation of the study area by carrying out observations, sampling and in-situ measurements of each borehole, as well as the good conservation of the samples taken in a cooler. The various measurements that we took in-situ: pH, electrical conductivity, turbidity, salinity, temperature, and TDS were carried out by using a multi-parameter probe in the laboratory of appropriate methods such as titled-sorting, spectrophotometry, atomic absorption spectrometry, ArcGise and Excel software. With regard to the results from laboratory analysis (physical and chemical analysis), the parameters showed that the standards recommended by the WHO were not respected. We affirm that the water consumed in the Mitendi South-East district in Mont-Ngafula town ship is not drinkable. Since, it can cause several water-borne diseases. It would be better to treat that water before being drunk. .

An Assessment of Saltwater Intrusion in Coastal Regions of Lagos, Nigeria

This paper explains various factors that contribute to saltwater intrusion, including overexploitation of freshwater resources and climate change as well as the different techniques essential for effective saltwater intrusion management. The impact of saltwater intrusion along coastal regions and its impact on the environment, hydrogeology and groundwater contamination. It suggests potential solutions to mitigate the impact of saltwater intrusion, including effective water management and techniques for managing SWI. The application of A.I (assessment index) serves as a guideline to correctly identify wells with SWI ranging from no intrusion, slight intrusion and strong intrusion. The challenges of saltwater intrusion in Lagos and the salinization of wells were investigated using the hydro-chemical parameters. The study identifies four wells (“AA”, “CMS”, “OBA” and “VIL”) as having high electric conductivities, indicating saline water intrusion, while other wells (“EBM”, “IKJ, and “IKO”) with lower electric conductivities, indicate little or no salt-water intrusion, and “AJ” well shows slight intrusion. The elevation of the wells also played a vital role in the SWI across coastal regions of Lagos. The study recommends continuous monitoring of coastal wells to help sustain and reduce saline intrusion. The findings of the study are important for policymakers, researchers, and practitioners who are interested in addressing the challenges of saltwater intrusion along coastal regions. We assessed the SWI across the eight (8) wells using the Assessment Index to identify wells with SWI. Wells in “CMS” and “VIL” has strong intrusions. A proposed classification system based on specific ion ratios categorizes water quality from good (+) to highly (-) contaminated (refer to Table 4). These findings underscore the need for attention and effective management strategies to address groundwater unsuitability for various purposes.

Determine the most appropriate strategy for groundwater management in arid and semi-arid regions, Abhar Plain, Iran

Due to growing demand and reduction of water resources and increasing pollution of water,driven by dramatic population and economic growth, arid and semi-arid land's imminent water problems are nowadays aggravating. This study aims to determine the most appropriate management strategies for balancing the Abhar plain aquifer using the SWOT coupled with AHP technique. The results indicate that weaknesses prevail over strengths as well as threats over opportunities. The placement in the quarter of weaknesses-threats with a defensive strategy indicates the critical condition of the Abhar plain aquifer. The most appropriate solutions to achieve the goal of balancing the groundwater were prioritized by AHP method. According to results, improper management of water consumption with a weight of 72.5% is the most destructive factor in reducing groundwater resources. Among the types of consumption, the effect of an agricultural factor carries a weight of 74.2%. The exploitation of illegal wells, overdraft of exploitation license provisions of wells, reduction of precipitation and traditional irrigation methods were selected as the destructive factors causing the deteriration of groundwater resources. Also, with filling the illegal wells,changing the type of cultivation and greenhouse crops cultivation, installing a smart water meter,observance the provisions of the water exploitation license, implementing integrated pressurized irrigation systems, benefiting from suitable climatic conditions and geographical location for cultivating and developing the low-water use species and industries and on the other hand, with implementing artificial recharge to control the surface water resources and reduce abstraction from groundwater aquifers, the adverse trend of Abhar Plain groundwater resources can be controlled.

A CO_(2) storage potential evaluation method for saline aquifers in a petroliferous basin

According to the requirements for large-scale project implementation, a four-scale and three-level CO_(2)storage potential evaluation method is proposed for saline aquifers in a petroliferous basin in China, considering geological,engineering and economic factors. The four scales include basin scale, depression scale, play scale and trap scale, and the three levels include theoretical storage capacity, engineering storage capacity, and economic storage capacity. The theoretical storage capacity can be divided into four trapping mechanisms, i.e. structural & stratigraphic trapping, residual trapping, solubility trapping and mineral trapping, depending upon the geological parameters, reservoir conditions and fluid properties in the basin. The engineering storage capacity is affected by the injectivity, storage security pressure, well number, and injection time.The economic storage capacity mainly considers the carbon pricing yield, drilling investment, and operation cost, based on the break-even principle. Application of the method for saline aquifer in the Gaoyou sag of the Subei Basin reveals that the structural & stratigraphic trapping occupies the largest proportion of the theoretical storage capacity, followed by the solubility trapping and the residual trapping, and the mineral trapping takes the lowest proportion. The engineering storage capacity and the economic storage capacity are significantly lower than the theoretical storage capacity when considering the constrains of injectivity, security and economy, respectively accounting for 21.0% and 17.6% of the latter.

Can rainfall seasonality trigger soil water repellency in a tropical riparian forest?

Though riparian areas generally have a shallow water table and higher soil moisture compared to up slope areas,climatic seasonality may trigger water repellency in tropical riparian forests,which,if persistent,could negatively affect essential ecosystem functions related to water resources protection such as reduced overland-flow,sediment transport,and nutrient filtration.The objective of this study was to answer the following:can tropical riparian forests develop water repellency?If so,does water repellency affect infiltration on a seasonal basis?For this,water repellency and infiltration were measured in a grid of 72points during a dry and a wet month of a tropical riparian forest with a shallow water table in a region with highly marked climatic seasonality.Water repellency and infiltration were significantly different between the wet and dry months.Water repellency affected negatively infiltration in the dry month,its effect in the wet month was insignificant.As a result,a higher infiltration capacity was observed over the wet period.Previous research has claimed that the development and persistence of repellency in soils could promote other hydrological processes such as overland flow.The findings shown here demonstrate that such phenomenon does not persist longer than the dry season.

Simulation of transport mechanism of radium isotopes in aquifer on the southern coast of Laizhou Bay

Naturally occurring radium(^(223)Ra,^(224)Ra,^(226)Ra,and^(228)Ra)isotopes have been widely applied as geochemical tracers in marine environments,especially when estimating the submarine groundwater discharge(SGD).In this sense,the influencing factors and transport mechanism of radium isotope activity in aquifers can be key information for SGD estimation.This work evaluates the adsorption/desorption behavior of^(224)Ra and^(226)Ra in the solid-liquid phase through a leaching experiment and analysis of field data.The results suggested that radium isotope activity was positively correlated with salinity and grain size,in the case of abundant sediments.Through ion analysis,we found that the ions(Na^(+),Ca^(2+),Mg^(2+),and Ba^(2+))exchanged with radium isotopes in the process of transport.A 1-D reactive transport model was established to simulate the transport process of radium isotope in aquifers.The model successfully simulated the variation of radium isotope desorption activity with salinity and was subsequently verified in the field.This study contributes to the understanding of the geochemical behavior of radium isotopes in aquifers and provides guidance for selecting a suitable groundwater endmember in SGD estimation.

COCKPIT-PLUS:A proposed method for rapid groundwater vulnerability-driven land use zoning in tropical cockpit karst areas

Karst groundwater is highly vulnerable to contamination,which urges better land use zoning.This paper proposes a new approach,called COCKPIT-PLUS,to minimize groundwater contamination within cockpit karst regions.The method employed four parameters:P(the existence of ponor/swallow hole),L(lineament density),U(sinking stream to an underground river),and S(distance to spring/pumping site).These parameters are essential for identifying contaminant pathways and transport from the surface to the karst groundwater/springs.COCKPIT-PLUS has been developed and validated in the Gunungsewu karst in Java,Indonesia.This research considers a cockpit as a single hydrological unit that uniquely recharges karst groundwater.We analyzed 2,811 cockpits and 81 other closed depressions to develop a land use planning map.The research used the time to first arrival(Ta),time to peak(Tp),and Q_(max/min)ratio parameters of two karst springs and two underground pumping sites for validation.Cockpits with ponors/swallow holes,sinking streams,high lineament density,and short distances to springs are vulnerable to groundwater and thus must be restricted areas for any land uses.The findings show that though the COCKPIT-PLUS uses a limited karst dataset,the proposed method seems reliable enough for a rapid land-use zoning approach in cockpit karst areas.