Hydraulic Conductivity Values Research Articles

Transport of dimethyl phthalate on loess with modified bentonite: A batch and column test investigation

Phthalic acid ester (PAE) is a toxic pollutant commonly found in high concentrations in municipal solid waste landfills. Soil–bentonite is widely used as a barrier material to control groundwater contaminants from landfill leachates. Traditional soil–bentonite materials always have a limited capacity for organic pollutant adsorption. To address this issue, the adsorption and transport behavior of dimethyl phthalate (DMP) on loess amended with two kinds of modified bentonite (HTMAC-B, modified with hexadecyltrimethylammonium chloride; CMC-B, modified with hydrophobic cationic surfactant, and carboxymethyl cellulose) were investigated. The kinetics of DMP adsorption indicates that film diffusion contributes significantly to the kinetic adsorption of DMP on HTMAC-B. The adsorption isotherm results showed that partitioning dominated DMP adsorption on loess with both modified bentonites. Owing to the in-ionic sites in HTMAC-B, which attracted hydrophobic compounds such as DMP, the adsorption capacity of 5 % HTMAC-B-amended loess (LH) was increased by a factor of 3.2. However, because CMC-B provided mostly ionic sites, 5 % CMC-B-amended loess (LC) had a little effect on DMP adsorption. The hydraulic conductivity values of LH and LC were 5.95 × 10−10 and 1.65 × 10−11 m/s, respectively. The X-CT result showed that there is a significant porosity change for both LH and LC. Dual-porosity model reveals that the leaching process primarily affects micro-pores, rather than larger pores in the soil matrix. The predicted retardation factors for LH and LC were 38.89 and 9.67, respectively. When using loess-bentonite as barrier material, the amendment of HTMAC-B and CMC-B can help to increase the retardation ability and reduce the permeability, respectively.

Hydraulic Conductivity Tests in the Triaxial Stress State: Is Peat an Aquitard or an Aquifer?

The characteristics of peat’s are crucial for understanding natural processes and their suitable shaping through the management of water relations. This study focused on the results of one of the first hydraulic conductivity (k) laboratory tests of exemplary peat samples from the Biebrza Valley (a peatland of very high environmental importance) in relation to the stress state and hydraulic gradient. Further, the research was devoted to a specific test procedure of peat permeability as a key feature for landform development in wetlands. Detailed tests of dark brown/black samples were selected as the reference for the research investigations. Four long-term test series of water permeability were performed in a modified triaxial compression apparatus. In all selected hydraulic gradient variants (i = 5,10,25,40,55,85), the k values decreased from 6 × 10−8 m/s to 1.6 × 10−10 m/s with a stepwise increase in the effective confining pressures tested (10, 15, 30, 45, and 90 kPa). These results were related to the inherent soil features—a relatively high peat decomposition and external driver—confining pressure (radial stress) magnitude. Compared to the other Polish peat tests, the determined k values were at the lower end of their hydraulic conductivity range. The analysed organic soil is not a typical aquifer. Despite very high porosities (~88%) and a high organic matter content (81.1–89.4%) which is favourable for water accumulation, the characterized peat showed relatively low hydraulic conductivity values. Thus, this specific soil may differentiate the groundwater flow as it complicates strong contact with surface water.

Modeling the river-aquifer via a new exact model under a more general function of river water level variation

The interaction between surface water and groundwater is a significant topic in groundwater-related problems. This study suggests an exact model based on Laplace transformation to calculate the groundwater flow in river-aquifer systems. Exact models play an important role in simulating the future behavior of river-aquifer systems. Therefore, investigation of the exact models for river-aquifer systems is a hot topic in the hydraulics of groundwater flow modeling. The objective of this research is to present new exact models for simulating the hydraulics of groundwater flow in river-aquifer systems with a more general function of river level variation under recharge by means of Laplace transform method. A general function is adopted to describe the river level variation, in which some situations such as linear, exponential and power of time variations in the river level can be treated as special cases. The effects of variations in aquifer parameters on groundwater hydraulic head are evaluated. It is shown that the groundwater hydraulic head grows slower in aquifers with a greater thickness or hydraulic conductivity. In addition, the effect of changes in specific storage is too little on the groundwater hydraulic head. The variations in hydraulic heads due to changes in recharge rate with different values of thickness, hydraulic conductivity, specific storage, and length are analyzed. It is observed that the groundwater hydraulic head in an aquifer with a lesser length, higher hydraulic conductivity or higher thickness is less sensitive to a change in the recharge rate than in an aquifer with a higher length, lesser hydraulic conductivity or lesser thickness. Furthermore, it is shown that the differences in hydraulic heads due to the increase in recharge rate are not significant for different values of specific storage. The results of the present new exact models are successfully verified by the results obtained from the analytical solution of Bansal and Das. Also, for more reliability, the results are compared with those results of MODFLOW. The results show that the presented new exact models are accurate, robust and efficient. One of the advantages of the solutions is to investigate the sensitivity analysis of aquifer parameters, which has been carried out in this paper. Furthermore, in the present research a more general function describing river level variation is considered, in which the linear, exponential and power of time variations are special cases.

Hydrogeological characteristics of waterlogged areas in Natore District, Bangladesh

Waterlogging (WL) refers to the process by which water flow is resisted in vertical and horizontal directions and thus water stagnates for a short or long span of time; it is induced by a combination of human and natural factors. In the southwestern region of Bangladesh, including Natore District, WL is a significant issue that needs to be addressed if agricultural activity is to be successful. This study aimed to identify surface WL in Natore District and to characterise the WL scenario in the study area in terms of hydrogeology. Waterlogged areas were identified with a geographic information system using satellite images corresponding to the premonsoon and postmonsoon periods. Using groundwater level data (1990–2017), the pre- and postmonsoon scenarios of the waterlogged areas were indicated by seasonal and perennial types of WL. Groundwater recharge scenarios were classified as long and short lag times. Most of the study area was characterised by thick clay or silty clay surficial layers with low water penetration rates, resulting from low porosity and low hydraulic conductivity. The cross-correlation between rainfall and groundwater level revealed the response of groundwater to rainfall, with a lag time of 1–5 months. Long lag time areas exhibited slow groundwater recharge and significant groundwater level fluctuation, with lower hydraulic conductivity values of 49.37–76.24 m/day. In contrast, short lag time areas displayed rapid groundwater recharge and small groundwater fluctuation due to a good proportional relationship with rainfall and higher hydraulic conductivity values of 74.74–117.79 m/day.

Repulsion driven by groundwater level difference around cutoff walls on seawater intrusion in unconfined aquifers

Cutoff walls have been widely used to prevent seawater intrusion (SWI) in coastal regions. Previous studies generally concluded that the ability of cutoff walls to prevent seawater intrusion depends on the higher flow velocity at the wall opening, which we have shown is not the most critical mechanism. In this work, we implemented numerical simulations to explore the driving force of cutoff walls on the repulsion of SWI in both homogeneous and stratified unconfined aquifers. The results delineated that the inland groundwater level was raised by cutoff walls, which generated a significant groundwater level difference beside two sides of the wall and thus provided a large hydraulic gradient to repel SWI. We further concluded that by increasing inland freshwater influx, the construction of cutoff wall could result in a high inland freshwater hydraulic head and fast freshwater velocity. The high inland freshwater hydraulic head posed a large hydraulic pressure to push the saltwater wedge seawards. Meanwhile, the fast freshwater flow could rapidly carry the salt from the mixing zone to the ocean and induce a narrow mixing zone. This conclusion explained the reason that the cutoff wall can improve the efficiency of SWI prevention through recharging freshwater upstream. With a defined freshwater influx, the mixing zone width and saltwater pollution area mitigated with the increase of the ratio between high and low hydraulic conductivity values (KH/KL) of the two layers. This was because the increase of KH/KL caused a higher freshwater hydraulic head, a faster freshwater velocity in the high-permeability layer, and the prominent change of flow direction at the interface between the two layers. According to the above findings, we deduced that any way to increase the inland hydraulic head upstream of the wall would improve the efficiency of cutoff walls, such as the freshwater recharge, the air injection, and the subsurface dam.

Agent-based modeling to assess decentralized water systems: Micro-trading rainwater for aquifer recharge

Decentralized aquifer recharge programs are an alternative to centralized stormwater aquifer recharge systems and can improve groundwater tables in urban areas. In a decentralized aquifer recharge program, households and property-owners collect and store rainwater from rooftops and replenish aquifers through small gravity-fed recharge wells. This research presents a micro-trading rainwater for aquifer recharge (MRAR) system as a decentralized peer-to-peer water market that can recharge groundwater resources. Through a decentralized water market, households act as prosumers who collect and sell rainwater to consumer households and convey traded water via a shared aquifer. This research develops an agent-based modeling framework as an approach to evaluate the performance of a MRAR system to replenish groundwater resources and reduce energy required to pump water. Agents represent (1) prosumers that collect rainwater, sell rainwater to consumers, and replenish the groundwater system through dry wells, and (2) consumers that exert irrigation demands, buy rainwater from prosumers, and pump water from the groundwater system. The agent-based model is coupled with a groundwater flow model to evaluate the effects of micro-trading on groundwater resources. The agent-based modeling framework is applied for a virtual city to assess the performance of a MRAR system for scenarios that vary in the ratio of consumers to prosumers, location of prosumers and consumers, and aquifer properties. Model outcomes demonstrate the optimal ratio of consumers to prosumers based on the volume of traded water, improvements in groundwater head, and improvements in unit energy of water. Findings demonstrate that the optimal ratio of consumers to prosumers is consistent across different values for hydraulic conductivity. The location of prosumer and consumer households affects the unit energy of water and has a negligible effect on the groundwater table and total energy consumed to pump water. This manuscript proposes and demonstrates MRAR as a new decentralized water system and provides a modeling approach to assess the performance of a MRAR system to improve urban groundwater resources.

The impact of vegetated landscape elements on runoff in a small agricultural watershed: A modelling study

Flooding of settlements is a growing concern in Europe, also in agricultural areas. Restoration and installation of vegetated landscape elements (vLE) such as hedges, lines of trees and grass buffers, along the parcel boundaries is increasingly recognized as a way to mitigate downstream flood risk. However, there is a lack of scientific evidence to support their implementation. We used the Landlab modelling framework to gain knowledge about the importance of the presence and characteristics of vLEs for the hydrological response in a 26 ha undulating watershed representative for the Belgian loess belt for which a multitude of vLE scenarios were developed. Our model results demonstrated that the total runoff volume, the peak discharge rate and its lag time in such small watersheds are mainly controlled by the density of the vLE objects and their upstream area. First and foremost we demonstrated a negative correlation between the discharge volume and peak discharge rate and the density of the vLE objects and their upstream area. A positive correlation was observed between the lag time and density of the vLE objects for both dry and wet soils and between the lag tag time and upstream area for dry soils. Further, we found that the impact of the value of the saturated hydraulic conductivity of the soil covered by the vLE became increasingly important with increasing soil wetness, with the hydraulic conductivity being negatively correlated with the discharge volume and peak discharge rate. The impact of hydraulic conductivity on the lag time was limited. A negative correlation between hydraulic conductivity and lag time for intermediate wet soils was demonstrated. Our model results also showed that the roughness, expressed as the Manning n-coefficient, of the soil underneath a vLE and the spatial connectivity of the vLE objects have little impact on the hydrological response.

Hydrogeophysical and Hydrochemical Assessment of the Northeastern Coastal Aquifer of Egypt for Desalination Suitability

Recently the limited freshwater resources have become one of the most significant challenges facing Egypt. Thus, new resources of drinkable water are required to meet the growing population demands and the national projects, to support the country’s economy. Saline groundwater desalination is an option that can support limited freshwater resources. This research represents a detailed analysis of hydrogeological and hydrochemical characteristics of a coastal aquifer in the West Port Said area, northeastern Egypt, to assess the desalination suitability of the aquifer, especially when the nearby seawater is contaminated. The hydrogeological characterization included various integrated approaches: geophysical survey, field investigations, wells drilling, well logging, pumping tests, and water sampling. The results show that: (1) The subsurface lithology consists of sandstone and clay, and three water bearing layers: A, B and C. (2) The average porosity values are 22%, 27.5%, and 25% for layers A, B, and C, respectively. The hydraulic conductivity values fall in the ranges of 5.8–12.7 m/day for layer A, 7.6–11.7 m/day for layer B, and 11.1–19.5 m/day for layer C, while the highest transmissivity values are in ranges of 5.8 × 102–12.7 × 102 m2/day for layer A, 7.6 × 102–11.7 × 102 m2/day for layer B and 11.1 × 102–19.5 × 102 m2/day for layer C. (3) The average storage values are 2.1 × 10−3, 1.8 × 10−3 and 5.3 × 10−3 in layers A, B and C, respectively. (4) Layers A and B showed Na-Cl-type, similar to seawater, but free from oil pollution. These results show layer B’s higher productivity and better quality. Despite the salinity, desalination technology can improve.

Assessment of geotechnical and geo-environmental behaviour of recycled concrete aggregates, recycled brick aggregates and their blends

The infrastructure development involves the demolition of non-functional establishments and the construction of the desired infrastructure needs, which generates construction and demolition (C&D) waste in enormous volumes. The demolished concrete and brick wastes are found mixed together, if not separated before crushing. Therefore, the geotechnical behavior of blends of recycled concrete aggregate (RCA) and recycled brick aggregates (RBA) with different proportions should be identified in order to find their suitability in geotechnical applications. This paper presents the geotechnical and geo-environmental characterization of RCA, RBA, and their blends (75RCA-25RBA, 50RCA-50RBA, 25RCA-75RBA). The recycled waste aggregates and their blends under this study have excellent shear strength, hydraulic conductivity, and compaction characteristics. The values of cohesion intercept (c) and angle of internal friction (ф) are found in the range of 50 to 63 kPa and 55˚ to 71˚, respectively. It is observed that the optimum values of shear strength parameters (c = 63 kPa, ф = 64˚), hydraulic conductivity (3.12 × 10-5 m/s), and compaction characteristics (OMC = 11.50 %, MDD = 1.96 gm/cm3) are found for 50 % RBA content in RCA-RBA blends. The water absorption is found on the verge of upper bounds considering pavement applications. The impact and crushing resistance of blends are found comparably low and decrease with increased RBA content in RCA. Therefore, their applicability to the surface course, even to the base course in pavements, may be restricted. Based on experimental results current study suggested that up to 50 % RBA content in RCA-RBA blends may provide satisfactory performance in various geotechnical applications like: pavement base and sub-base, fill material in embankments and reinforced earth structure, etc.

Physico-chemical Properties in Rhizosphere of Some Field Crops at Different Growth Stages in a Sandy Clay Loam Soil in Sourthern Nigeria

The effects of different cultivated crops and their growth periods on some hydraulic and chemical properties of a sandy clay loam soil at the University of Port Harcourt, Teaching and Research Farm, in Choba, Rivers State, Nigeria was studied. The objective was to understand the changes in soil physical and chemical properties near the plant environment during the growing period for optimum management. Four (4) crops: Maize (Zea mays L.), Okra (Abelmoschus esculentus), Pepper (Capsicum annuum), and Garden egg (Solanum melongena F.) were planted to native fallowed soil and the soil properties measured at three (3) growth stages of the crops viz: Establishment, Flowering, and Maturity. Results revealed that the plants did not modify the soil textural class. Significant changes in bulk densities and saturated hydraulic conductivity were found during the flowering stage of the crops. Bulk density of 1.36 and 1.34 g cm-3 were significantly (p<0.05) low at during flowering and maturity stages, respectively, in Garden egg soils. The highest saturated hydraulic conductivity (Ksat) values of 22.9 and 27 cm h-1, respectively, were significant (p<0.05) during the same periods for garden egg, followed by Maize and Okra. Results also revealed that Okra, Pepper and Garden egg significantly (p<0.05) reduced the soil acidity at flowering growth period. Maize contributed significant additions of soil organic matter to the soil at flowering and maturity periods. Maximum removal of available plant nutrients was at flowering stage for maize when more than 80% of the plant had shown tasselling and cob formation. Therefore, monitoring the growth stages of specific plant could help in nutrient and soil management and changes in soil physical and chemical properties.

ANALISIS KONDUKTIVITAS HIDROLIK JENUH TANAH PADA BERBAGAI JENIS NAUNGAN DI LAHAN KOPI RAKYAT KECAMATAN SUMBERMANJING WETAN

Coffee plants are one of the plantation crops that are widely cultivated by smallholders in Sumbermanjing Wetan District. The problem that is often experienced by coffee farmers is the decline in coffee production due to climate. The adverse effect of climate change can be overcome through mitigation by implementing shade plants. The saturated hydraulic conductivity of the soil is defined as the movement of water in a porous medium in a saturated state. By measuring hydraulic conductivity, it can determine the ability of the soil to conduct water and see the movement of water in the soil. The highest value of saturated hydraulic conductivity at a depth of 0-20 cm was found in coffee plants with sengon shade at 31.02 cm hour-1. The highest value of saturated hydraulic conductivity at a depth of 20-40 cm was found in coffee plants with the shade of Dadap plants, which was 56.67 cm hour-1, included in the fast category. Differences in shade and soil depth in coffee fields affect the value of the saturated hydraulic conductivity. There is a relationship between several physical properties of the soil and the saturated hydraulic conductivity of the soil. The physical properties of the soil affect the saturated hydraulic conductivity of the soil.

Avaliação da vulnerabilidade natural de aquíferos subterrâneos visando à hierarquização de locais para implantação de sistemas de abastecimento de água e esgotamento sanitário no município de Ananindeua/PA

ABSTRACT The methodologies for determining aquifer vulnerabilities are currently used as tools to support proposals for the groundwater protection, associated to water management resources and planning and territorial ordination activities. In this context, the objective of this present work is the vulnerability assessment of an aquifer system of interest located in the municipality of Ananindeua, the state of Pará. To this end, the following activities were executed: survey and systematization of pertinent information to existing wells in the municipality of Ananindeua-PA; determination of the constituent parameters of the GOD method and the hydrogeological values of hydraulic conductivity and hydraulic transmissivity; extrapolating the pertinent information for all the interest area aiming the spatialization of homogeneous zones by degree of vulnerability e, finally, the hierarchization of locations for the implementation of water supply systems. With the completion of this present work, it was verified that most part of the area of interest has an aquifer system classified as unconfined, mixed lithological extracts and distance from the top to the water table less than 20 meters. These information, associated with the pattern of land use and occupation, based on the study of hydrogeologic values, enables the subsidy for decision-making regarding the most appropriate allocation of preventive investments with basic sanitation infrastructure, in order to minimize or nullify the associated risks of contamination in the referred area. However, to a better support for an efficient decision-making from the public managers and the actions of other social actors involved in the use and management of groundwater in the locality, it must be provided other information and complementary studies.

Assessment of Unconfined Aquifer Hydraulic Characteristics Using Self-Potential Method: Case Study in Laylan Sub-Basin, Kirkuk, Iraq

This study aims to evaluate the hydraulic characteristics of the unconfined aquifer in the Laylan area, Kirkuk, Iraq. The pumping test was carried out on four wells in the Laylan area. all wells penetrate the quaternary sediment, which consists of sand, gravel and clay, the monitoring of the change in the groundwater table was carried out by the groundwater depth detector and the self-potential device, as the purpose of this study was to find an alternative to the traditional methods that monitor the draw down during pumping test, whose use is often accompanied by many obstacles and especially most of the wells belong privately to the farmers, where the goal was to find a relationship between the self-potential readings and the change of the water depth that measured by groundwater depth detector. a mathematical relationship was obtained that links the values of the two variables. In addition, the conductivity value was calculated by substituting the self-potential value in the equation to find the draw down values and then entering into the aquifer-win program. The geophysical self-potential value is very sensitive to the groundwater level changes the correlation coefficient between each of them as in the wells (pw1, pw2, pw3 ) is 0.95,-0.83 and -0.86 respectively, It is a strong and inverse relationship. Transmissivity values for the wells PW1,PW2,PW3 ,PW4 were 12.32 m2 /day, 17.22 m2/day, 78.29 m2/d (10 m2/d) respectively and the hydraulic conductivity for the wells PW1, PW2, PW3, PW4 were 0.113 m/day, 0.21 m/day, 1.74 m/day, 0.25 m/day respectively the obtained hydraulic conductivity value was an approach to the hydraulic conductivity values obtained in the traditional methods. Therefore, the equation can be used in aquifers if it was in the same conditions as this basin. Therefore, the SP device can be considered a successful alternative to traditional measurement methods.

Effect of clay fouling on track drainage capacity of railway Ballast: Experimental and numerical study

Ballast fouling is a key contributor to the instability of ballasted railway tracks due to its detrimental influence on the permeability of the ballast layer. Predicting the track drainage condition in a ballasted track segment frequently affected by fouling is vital for planning track maintenance activities. However, only limited studies have been conducted to assess the hydraulic conductivity and track drainage capacity of fouled railway ballast. Hence, full-scale permeability tests were performed in this study using an in-house custom-built large-scale permeability apparatus at the laboratory to attain hydraulic conductivities for 5 different fouling levels of ballast fouled with sandy lean clay material. Based on the experimental results, a relationship between the Void Contamination Index (VCI) and hydraulic conductivity was obtained. The results elucidated that the fouling material reduced the hydraulic conductivity of ballast by more than 90% when VCI was 25% or higher. In addition, using the hydraulic conductivity values obtained from experimental results, a detailed 2D numerical seepage analysis of a rail track was carried out to represent the track drainage capacity at various fouling levels. Based on the results, the significance of maintaining a clean top ballast layer and shoulder ballast was highlighted and a criterion for estimating the drainage capacity of a clay-fouled railway track was proposed to initiate track maintenance operations.

Aquifer characteristics and groundwater flow system in a typical basement complex and Gundumi formation northwest, Nigeria

Aquifer performance was tested in 280 locations of the study area to assess the hydraulic characteristics of the various aquifers, potential yield from the flowing boreholes of both hard rocks and sedimentary formation underlain Zamfara State Northwestern, Nigeria. Pumping test result were subjected to standard methods of Jacob’s and modified Theis equation for evaluation of aquifer parameters such as hydraulic conductivity (K), Transmissivity (T), Specific capacity and others. The results show that characteristic of areas underlain by crystalline rock units, especially migmatite, variably migmatized gneiss, schists and granites are characterized by thin/shallow overburden unit of usually less than 10m. In such settings the borehole depth varies from 38 to 78m while saturated thickness varies from 8 to 20m below ground level, with average yield of 44.1m3/day. Hydrogeological parameters obtained from pumping test analysis within the basement rock units revealed aquifer transmissivity (T) values which range from 0.14 to 141.23m2/day, with an average of 12.85m2/day. This implies aquifers of negligible to high potentials. The hydraulic conductivity (K) values vary from 5.0 x 10-2m/day and 8.8 x 10-1m/day with an average of 2.2 x 10-1m/day. The implication of these results is that the aquifers of the basement rock units cannot provide sufficient water for both domestic and agricultural needs of the area. However, Sixty-eight (68) analyzed borehole data set within Gundumi Formation, revealed the average discharge rate of 116.8m3/day. This formation shows the highest water discharge within the study area. The average penetration depth of 65m was achieved. The hydraulic conductivity of this aquifer revealed average value of 5.7 × 10-1m/day. This implies high permeability of aquifer system, which is typical of sedimentary formation of this nature. Transmissivity (T) revealed an average value of 38.89m2/day, which indicate high rate of water flow through the entire aquifer medium of this formation. The geospatial analysis of yield from the wells indicate excellent groundwater potential around the western part of the study area.

Modeling of groundwater potential in Kericho County, Kenya, using GMS_MODFLOW

Groundwater is a major source of water supply in Kericho County, Kenya. However, this water source is threatened by the rise in the human population and climate change. Under these conditions, it is crucial to assess the sustainability of the groundwater resource in Kericho County. Thus, this study aimed to investigate the potential of groundwater in Kericho County, Kenya. Groundwater Modelling System (GMS) software was used to develop a conceptual model to aid in the assessment of groundwater. Results from calibration showed hydraulic conductivity values varying from 0.279 to 1.12 m/d, while the recharge rates ranged from 0.5 to 0.00022 m/d. Also, a predictive run was conducted in the calibrated model to examine the aquifer's response to abstractions under three different scenarios. Scenario 1 assessed the impacts of population growth on groundwater resources; scenario 2 evaluated the effects of climate change on groundwater; scenario 3 assessed the effect of population growth and climate change on groundwater in the study area. The results showed that excessive pumping rates interfere with the surface water and groundwater interactions. There was slight decline in constant head for location near the river. However, the recharge rate was higher than the abstraction, indicating that groundwater will remain sustainable as the primary source of water supply for the residents. In conclusion, the volumetric budget for the three scenarios shows that the aquifer has sufficient water supply to be used by the population despite the effects of climate change and population growth. Despite the availability of adequate water supply from the aquifer, there is a need for an effective and sustainable use of water from the aquifer, especially in the face of climate change and population increase.

Parameter allocation approach for runoff simulation in an arid catchment using the KINEROS2 hydrological model

AbstractThe KINEROS2 model was utilized for runoff simulation in the Dehgin catchment situated in the Hormozgan province of Iran. A parameter allocation procedure was used in lieu of parameter optimization. After parameter allocation, the model was able to adequately simulate hydrographs associated with high‐magnitude peak discharge events with the efficiency values between 0.011–0.83 for Nash–Sutcliffe and 0.36–0.98 for Kling–Gupta, but the model did not accurately simulate hydrographs corresponding to low‐magnitude peak discharge events. Although calibration after parameter allocation improved model performance with respect to the simulation of low‐magnitude discharge events, numerical values of the hydraulic conductivity and net capillary pressure as the most sensitive model parameters did not agree with parameters known to be reasonable in the region. So that the value of hydraulic conductivity was decreased from 61 to 55 mm/h in channels and from 3.7 to 1.7 mm/h in planes. The new values are physically reasonable but are not approximately the same as physical values associated with the regional and environmental context of the Dehgin catchment. In this case, the values of the evaluation criteria were obtained between −2.5 and 0.78 for Nash–Sutcliffe and 0.17 and 0.98 for Kling–Gupta. The results of using the HydroPSO package in R to automated calibration of the model, with the value of Nash–Sutcliffe between −0.63 and 0.43, indicated that autocalibration without intelligent and deliberate selection of parameters cannot accurately represent hydrological processes, and therefore should be avoided. Also, the results show that an understanding of the catchment environmental conditions and appropriate allocation of parameters is initially more effective as a first step of the modeling process and thereby contributes to a first‐order characterization of environmental conditions in the catchment.

EFFECT OF PHOSPHOGYPSUM IN SOME PHYSICAL PROPERTIES OF SOIL

Alaboratory experiment was carried out during 2020 in the laboratories of the College of Agriculture / University of Anbar in order to study the role of phosphogypsum in the values ​​of saturated hydraulic conductivity, capillary height and water holding capacity of soil in clay soil. The phosphogypsum was added mixed with the soil at four levels (without adding, 0.3%, 0.6% and 0.9%) by weight of the soil. The treatments were incubated for 90 days by adding water at the limits of the field capacity and compensation the lost water after deplete 50% of the available water. The amount of available water, the saturated hydraulic conductivity, and the capillary height has been estimated. The soil water holding capacity increased significantly, which was 16.91% at the addition of 0.9% compared to the treatment without addition. While the highest value of the saturated hydraulic conductivity was 0.35 cm per hour -1at the level of 0.9% addition. The capillary height decreased significantly with the increase in the level of phosphogypsum addition, and the lowest value was 52 cm when adding 0.9%.

Groundwater Heat Pump assessment operation in three cities of south-central Chile: An approach based on aquifer characterization and analytical calculations of Thermal Affectation Zone

The aim of this work is the Groundwater Heat Pump (GWHP) assessment in three cities in south central Chile (Talca, Temuco, and Osorno), considering the hydraulic parameters of the aquifer, its temperature, and the Thermal Affectation Zone (TAZ) generated around the reinjection well due to the reinjected water flow, and temperature difference, due to thermal recovery.According to the hydraulic characterization, the conditions are more favorable in the city of Talca, where the hydraulic conductivity is medium to high. On the other hand, in the cities of Temuco and Osorno, the hydraulic conductivity is low or very low, except in some domains of river belts, where the hydraulic conductivity is medium to high. In all cities, the temperature of the aquifer is very good for heating and cooling. In particular, in Talca downtown there is a positive thermal anomaly that improves the GWHP performance for heating purposes.In each city, the extension of the TAZ was calculated for a reinjection rate of 5 [L/s], and a thermal recovery of 3 [°C] (heating). In each city, the TAZ was calculated for the hydraulic conductivity values corresponding to the percentiles 25, 50, and 75. The hydraulic gradient is fixed for each city. The heating time increases from north to south (Talca, Temuco and Osorno) due to the climate. In all cities and in all cases, temperature dispersion due to groundwater flow is moderate to slight and concentrated around the reinjection well. The largest extension of TAZ in the direction of groundwater flow is calculated in Talca, reaching approximately 30 m. On the other hand, the greatest reach of TAZ in the opposite direction to the groundwater flow is calculated in Osorno, reaching approximately 20 m. The effect of varying injection rates (3, 5 and 10 L/s) does not significantly affect the distance range of TAZ, yet affects the concentration of TAZ around the reinjection well.

Understanding of groundwater evolution through chemical and age dating information in the Yongding River alluvial fan in Beijing

Groundwater plays important roles in human community development and the urbanization process as the results of global environmental change and rapid population growth. A clear understanding of the vertical and horizontal spatial distribution characteristics of groundwater and sediment is the premise of efficient groundwater resource management and utilization in alluvial plains. To explore the evolution process of groundwater and the distribution of sediment in the Yongding River (YDR) alluvial fan, a typical profile from Mentougou to Fengheying was chosen to conduct an extensive hydrogeological investigation with multiple hydrochemical, isotopic, and age dating analyses, which represents one of the most typical hydrogeological units in the YDR alluvial fan. The analysis results show that (i) along the profile, the water’s chemistry type gradually changes from HCO3-Ca·Mg to HCO3-Na. The contents of coarse grain gradually decrease while fine particles regularly increase. Also, a similar evolution trend is found in the vertical direction. (ii) The annual renewable rate of groundwater is > 10% in the upper fan, 2%–8% nearby Daxing, and < 2% in Fengheying. (iii) In the proximal fan area, the average flow velocity of the single and double layer is about 65 m yr−1 and of approximately 18.9 m yr−1. From the mid fan to distal fan, the value of velocity and hydraulic conductivity decreases from 12.4 m yr−1 to 3.75 m yr−1 and from 8.54 m yr−1 to 0.64 m yr−1, respectively. (iv) The 14C analysis results indicate that the age of shallow and deep groundwater ranges from 5a to 60a and from 4000a to 12000a, respectively. The groundwater age increases with depth in the vertical direction and increases from northwest to southeast along in the alluvial fan in the horizontal direction. Understanding the evolution process of sediment and hydrochemistry in the YDR alluvial fan provides a valuable reference for groundwater resource development, utilization, and pollution prevention in the alluvial fan.