Increase In Groundwater Level Research Articles

Spatial assessment of land use and land cover change impacts on groundwater recharge and groundwater level: A case study of the Hat Yai basin

Study regionHat Yai Basin, Thailand. Study focusThis study aimed to assess the impacts of land use and land cover changes on groundwater recharge and groundwater levels—specifically, the effects of increasing built-up areas and urban expansion. The MOLUSCE (plug-in QGIS) software was used to analyze land use and land cover changes. The groundwater recharge estimation in this study was conducted using the WetSpass model, and the groundwater level was simulated using MODFLOW. New hydrological insights for the regionThe findings indicate that the Hat Yai basin has experienced its highest increase in built-up areas and found a decrease in the average recharge rate for 2017 compared to 2007. Correspondingly, a simulation of groundwater levels indicates that the overall groundwater level has decreased. Spatially, the Hat Yai district, which exhibited the highest increase in built-up areas, experienced a decrease in groundwater levels. In contrast, the Khuan Niang district, which had the largest increase in perennial areas, demonstrated increased groundwater levels. The findings show that increasing built-up areas decreases the recharge rate, consequently lowering groundwater levels. The spatial assessment is proved to be more effective in illustrating positive and negative impacts than the basin's overall average. Such spatial assessment is valuable for water resource management planning and addressing localized water resource issues that may differ across various areas.

Cut-off walls alter nitrogen loads and fluxes in small islands

The measure of constructing cut-off walls in coastal islands has been tested effective to upgrade the freshwater lenses (FWL). Meanwhile, cut-off walls can also affect the FWL quality by changing the loads and fluxes of nitrogen (N). Previous research has been focused on the effects of cut-off walls on the N fluxes in groundwater (like, e.g., nearshore denitrification), assuming a constant N source while changes of the N loads and fluxes associated to the N source in shallow soils have only rarely been considered. In this study, we numerically simulated seawater intrusion and transport of land-sourced nitrate on a 2D, vertically oriented island equipped with a cut-off wall. A simplified framework was used to simulate the N fate in the shallow soil. We selected different aquifer permeability and the depth of cut-off wall. The cut-off wall effect on the N loads and fluxes in soil and groundwater, and on the nitrate concentration within the FWL, was quantitatively assessed. The results show that cut-off walls can considerably reduce the soil N load in high permeability islands (> 10−11.5 m2), because of the increased potential crop uptake due to the increased groundwater level and higher soil moisture. The opposite effect was observed in low permeability islands (< 10−11.5 m2) due to the smaller N leaching fluxes from soil to groundwater under the reduced groundwater flow rate. For the high and low permeability islands the leaching flux can generally be reduced by up to 63 %; for the intermediate permeability islands (10-11.5 m2 ≤ k ≤ 10-11 m2), however, the leaching is increased by up to 38 %. Highly depending on how the leaching changes, cut-off walls can reduce the groundwater N load and the nitrate concentration of FWLs, and thus improve the FWL quality in many cases except for the intermediate permeability islands. Therefore, special caution and investigation are required for constructing cut-off walls on islands with intermediate permeability. As a first attempt to assess the influence of cut-off walls on N loads and fluxes considering the N source dynamics, our study is important for the management of FWL quality and coastal environments.

Forecasting the groundwater levels in the Baltic through standardized index analysis

In regions where groundwater forms the primary source of drinking water, comprehending the prospective availability of subsurface water resources due to climate change is of paramount importance.This study evaluates the impact of climate change on groundwater levels in the Baltic States until the end of this century. It employs link between surface and subsurface standardized indices. For forecast it uses various Representative Concentration Pathways (RCP) alongside different Regional Climate Models (RCM).By linking historical groundwater drought episodes with calculated surface drought indices and accumulation periods observed during defined climate Normals, we project groundwater levels for the short, medium, and long-term future. The study incorporates 13 EURO-CORDEX RCMs under three RCP scenarios.Our analysis reveals that, compared to the recent climate Normals, an overall increase in groundwater levels is expected at most study sites. However, lower groundwater levels are estimated in the near future. The projected impacts show no significant seasonal bias or spatial conformity. Although these findings are specific to the Baltic region, the methodologies described can be readily adapted for global application.

Assessment of the impact of greenhouse rainwater harvesting managed aquifer recharge on the groundwater system in the southern Jeju Island, South Korea: Implication from a numerical modeling approach

Managed aquifer recharge (MAR) is increasingly being adopted worldwide to mitigate groundwater depletion and ensure the sustainability of water resources. Rainwater harvesting (RWH)-MAR can augment aquifer storage and reduce flood damage in rural areas with dense greenhouse facilities. This study has assessed the feasibility of greenhouse RWH-MAR in Namwon agricultural areas in the southern part of Jeju Island, South Korea, by considering the injection rate and location of MAR using a numerical model. The model results showed that groundwater level increases were directly related to the infiltration rate, although spatial differences in head rise were observed owing to the spatial variability of hydraulic conductivity. In addition, installing the RWH-MAR in highland areas (>100 masl) enhanced the water level rise when compared to the expected values, indicating that a higher hydraulic gradient and thick unsaturated zone facilitated more effective MAR outcomes than in lowland areas. To optimize the contribution of source water to the agricultural water demand, placing the RWH-MAR near the pumping well improved the availability of injected rainwater to agricultural wells. This study highlights the importance of designing RWH-MAR schemes considering MAR objectives and the topographic and hydrogeological characteristics of the site.

Hourly estimation of water reaching the ground surface in snow-covered regions of Japan using mesoscale meteorological data with the heat balance method

In snow-covered regions, landslides, including debris flows, frequently result from snowmelt and cause significant hazards. Because these snowmelt-induced landslides are triggered by increasing groundwater level and pore-water pressure acting on the slip surface due to infiltration of snowmelt, sometimes mixed with rainwater, accurate estimation of water reaching the ground surface (abbreviated MR in this study) on an hourly basis is essential for developing countermeasures such as an early warning system. This study introduces a model for estimating hourly MR, as well as snow water equivalent and snow depth, using mesoscale meteorological data provided by the Japan Meteorological Agency. The model considers four processes: precipitation, snow accumulation and densification, snowmelt, and infiltration. In the snowmelt process, snowmelt is estimated using the heat balance method. We applied the model to a snow observation station in Niigata Prefecture, central Japan, where MR, snow water equivalent, and snow depth were observed during the winter seasons of 2017–18 through 2020–21. Comparisons of observed and calculated values demonstrated that the model successfully reproduced the observations, regardless of the amount of snowfall in individual winter seasons. We propose that this model can estimate hourly MR, snow water equivalent, and snow depth at any location in snow-covered regions where on-site meteorological and snow observations are unavailable.

Application of Sponge City for Controlling Surface Runoff Pollution

Nowadays, due to the complexity of urban growth and the frequency of extreme stormwater events, flooding has emerged as a major global problem. Scientists and engineers are competing to find the best and most economical ways to prevent flooding. In 2014, China introduced the concept of a sponge city, similar to the low-impact development (LID) approach, comprising several facilities to prevent flooding. In addition to preventing flooding, this approach offers various benefits such as increasing groundwater levels and expanding green spaces. Sponge city is based on four basic principles: urban water resourcing, ecological water management, green infrastructures, and urban permeable pavement. It involves transforming urban infrastructures into green infrastructures. This review analyzes insights from more than 50 articles focusing on various sponge city facilities and classifying them based on their roles in infiltration, retention, storage, purification, use, and drainage. It also compares Sponge city with traditional runoff management approaches. Overall, this review aims to deepen our understanding of modern urban water management strategies and their implications for sustainable development.

Development of a coupled surface water–groundwater model for the spatiotemporal simulation of river–aquifer interactions

AbstractIntegrating surface and groundwater use is a crucial part of water management. When one type of water is depleted, the other follows suit because of the constant movement and interaction between them. Therefore, the primary objective of this research is to establish a method by which the water evaluation and planning system (WEAP) surface water model and the MODFLOW groundwater model can communicate with one another. This article aims to demonstrate the interdependence of groundwater and surface water. Here, we use MODFLOW to model the saturated soil region and the soil moisture method to model the unsaturated soil region. The interaction between surface water and groundwater will affect the region's water resources and how they will operate under the continuance of existing practices. The simulation of saturated and unsaturated soil zones using a connected model of surface and groundwater employing all the hydroclimatology balance components is one of the most significant accomplishments of this research. The findings show that the (Iran) Sonqor Plain's maximum aquifer recharge throughout the months of November to May during a period of 30 years (October 1991 to September 2020) ranges between 1.5 and 2.6 million m³. A lack of recharge from irrigation water infiltration occurs in some of these months in addition to rain. The highest rate of groundwater level increase in this area is 4.5 m yr⁻¹ as a result of the distribution of irrigation water provided from the dam in the north‐western region.

THE INFLUENCE OF WASTE ACCUMULATION SITES FROM MINING AND PROCESSING PLANTS ON THE HYDROSPHERE OF ADJACENT TERRITORIES

The nature and directions of changes in the state of water bodies of the territory, for a long time (50 60 years) adjacent to the storage areas of mining waste (dumps) and enrichment (tailings) of iron ore raw materials, have been studied. It has been established that dumps and tailings are sources of the adjacent territories’ intense hydrosphere chemical pollution with highly mineralized filtrates. The most intense pollution and increase in groundwater levels at all horizons occurs in the first 10-15 years.In the future, in proportion to the service life of man-made structures, the area and level of chemical pollution of surface and underground water bodies increases, hydrogeological processes are increasing: flooding of lands, landslides, sinkholes.

Centrifuge modeling of loess slope failure induced by rising water level utilizing intact sample

Understanding the failure process of bottom-saturated loess slopes is of great significance in loess areas where flood irrigation is commonly utilized to alleviate the scarcity of precipitation. In this study, the failure process of a loess slope with an increased groundwater level was recreated and the multiple failure modes of loess landslides were revealed. A centrifugal model test was conducted using a groundwater-recharge device. An intact loess sample retrieved from the Heifangtai Loess Terrace was employed in the test. The model test was monitored using a video recorder, high-speed camera, and soil/pore water pressure sensors, and the results were validated by utilizing an intermittently investigated field landslide. Based on the monitored data and acceleration, the test was divided into three periods: the initial acceleration period with no water inlet (0–40 g), bottom saturation period (40–60 g), and failure occurrence period (60–80 g). The soil/pore water pressure and degree of deformation were relatively low, with a steadily increasing trend during the first two periods. With the enrichment of the soil water content, retrogressive sliding, deep subsidence, and surface sinkhole failures occurred successively up to areas with relatively high pore water pressure during the last period. The results of the field landslide investigation showed multiple failure modes, as observed in the model test. The results suggest that the coexistence of multiple failure modes could gradually evolve into croplands and promote water infiltration into the deep loess, increasing the groundwater level and accelerating the failure process of the slope. Despite the overall effects of multiple failure patterns on the evolution of the slope, each failure pattern had a relatively independent evolutionary process within a certain area, which could be further analyzed for the early recognition of loess landslides. This study also indicates that the challenges of centrifuge modeling for water-related materials with intact soil samples are the boundary conditions and data monitoring within the model.

Groundwater Storage Variations across Climate Zones from Southern Poland to Arctic Sweden: Comparing GRACE-GLDAS Models with Well Data

The aim of this paper is to assess the correlation of groundwater level changes (or groundwater level anomalies (GWLA)) obtained from direct measurements in wells with groundwater storage anomalies (GWSA) calculated using Gravity Recovery and Climate Experiment (GRACE) products and Global Land Data Assimilation Systems (GLDAS) models across different climate zones, from temperate Poland to Arctic Sweden. We recognize that such validation studies are needed to increase the understanding of the spatio-temporal limits of remote sensing model applicability, not least in data-scarce sub-Arctic and Arctic environments where processes are complex due to the impacts of snow and (perma) frost. Results for temperate climates in Poland and southern Sweden show that, whereas one of the models (JPL_NOAH_GWSA) failed due to water balance term overestimation, the other model (CSR_CLM_GWSA) produced excellent results of monthly groundwater dynamics when compared with the observations in 387 groundwater wells in the region during 2003–2022 (cross-correlation coefficient of 0.8). However, for the sub-Arctic and Arctic northern Sweden, the model suitable for other regions failed to reproduce typical northern groundwater regimes (of the region’s 85 wells), where winter levels decrease due to the blocking effect of ground frost on groundwater recharge. This suggests, more generally, that conventional methods for deriving GWSA and its seasonality ceases to be reliable in the presence of considerably infiltration-blocking ground frost and permafrost (whereas snow storage modules perform well), which hence need further attention in future research. Regarding long-term groundwater level trends, remote sensing results for southern Sweden show increasing levels, in contrast with observed unchanged to decreasing (~10 mm/a) levels, which may not necessarily be due to errors in the remote sensing model but may rather emphasize impacts of anthropogenic pressures, which are higher near the observation wells that are often located in eskers used for water supply. For sub-Arctic and Arctic Sweden, the (relatively uncertain) trend of the remote sensing results nevertheless agrees reasonably well with the groundwater well observations that show increasing groundwater levels of up to ~14 mm/a, which, e.g., is consistent with reported trends of large Siberian river basins.

A causal physics-informed deep learning formulation for groundwater flow modeling and climate change effect analysis

In this study, we propose and test a formulation for building causal physics-informed hybrid models over traditional physics-informed hybrid models (H-HBVo) and a convolutional neural network (1D-CNN) in groundwater level (GWL) modeling. Two types of models are built based on our formulation and named H-HBV and H-Lin, because they integrate two different hydrological models. The comparison is made in terms of performance and ability to learn cause-and-effect relationships between inputs and outputs. The novelty of this study lies in the CRC (Causal Relationship Constraints) conditions, derived from a mathematical development, that are imposed on the layers of the physics-informed hybrid model to force it to learn causal relationships. The results showed that the 1D-CNN algorithm performed slightly better than the hybrid algorithms, and that the H-Lin and H-HBV algorithms together achieved slightly better results than the traditional hybrid algorithm, H-HBVo. It is also obtained that the algorithms subjected to our formulations (H-Lin and H-HBV) are the ones with satisfactory causality properties and that the integration of domain knowledge is not sufficient to obtain causal and interpretable models within the framework of hybrid algorithms. Subsequently, an analysis of the effect of climate change is carried out for Quebec (Canada) using H-HBV models. The results show that the RCP and SSP scenarios give fairly similar results, i.e. an increase in GWL between 2011 and 2090 with median amplitudes varying between + 5.6 and + 7 cm. In some cases, the amplitude of increase can exceed between + 14 and + 23 cm, and even reach between + 35 and + 70 cm. The results of the climate change analysis are consistent with changes in vertical inflow and potential evapotranspiration, the input variables, for the different climate scenarios, confirming the robustness of our formulation.

Estimating Groundwater Level in Peatlands by Using Submersible Sensor

Peatland fires pose a significant challenge in peatland management, with declining groundwater levels being a contributing factor. Real-time monitoring of groundwater levels (GWL) is essential to address this issue effectively. This study examines GWL data collected from submersible sensors and manual readings in peatlands of Tangkit Baru and Pematang Rahim villages, Jambi Province. Results reveal an increase in GWL in Tangkit Baru coinciding with rising precipitation, while Pematang Rahim experiences a contrasting decrease despite heavy rainfall. Statistical analysis, specifically t-tests, indicates no significant difference (p &gt; 0.05) between the two measurement methods. However, slight discrepancies (0.1-1 cm) between submersible sensor and manual measurements underscore the importance of sensor maintenance for accurate GWL assessment. Keywords: Peatlands, sensors, groundwater level

Hydrogeochemical processes as a conditioner of freshwater lenses associated with coastal deposits

AbstractThe aim of this work was to study the processes and factors conditioning the hydrochemistry of freshwater lenses associated with Holocene coastal deposits in an area of the Argentinean Atlantic coast. For this purpose, geomorphological units were mapped and a shallow groundwater monitoring network was established, including pre‐existing boreholes and shallow exploration wells. During the construction of the shallow exploration wells, sediment samples were extracted to determine the texture and mineralogical characteristics. Four samplings were carried out to measure in situ physicochemical parameters and to determine majority ions in the water. The chemical data were analysed considering the associated geomorphology, lithology, water balance and hydrodynamics. The geomorphological and lithological characteristics are the combined factors that favour the preferential rainwater recharge processes. Geoforms with greater topography and extension (continental and coastal dunes) tend to store freshwater lenses, while those with lower topography and little areal extension (sand sheets and beach ridges) have very thin lenses and tend to become salinized. Climate and local water balance are factor that determines that groundwater recharge occurs preferentially in winter. This causes increases in groundwater levels and a decrease in the groundwater EC. On the other hand, mineralogy is a factor that conditions the geochemical processes associated with the water–sediment interaction. Within the main geochemical processes, the dissolution and/or mineral weathering, the dissolution of CO2(g) and ion exchange determine the presence of different hydrochemical facies, where Ca‐HCO3 facies dominates in elevated geoforms, while Na‐Cl in lower ones. The results obtained in this work have provided an understanding of the factors and processes that condition groundwater chemistry in coastal deposits, being of vital importance for the management of water resources.

Suitability of treated wastewater for irrigation and its impact on groundwater resources in arid coastal regions: Insights for water resources sustainability

Water scarcity threatens agriculture and food security in arid regions like Saudi Arabia. The nation produces significant quantities of municipal wastewater, which, with adequate treatment, could serve as an alternative water source for irrigation, thereby reducing reliance on fossil and non-renewable groundwater. This study assessed the appropriateness of using treated wastewater (TWW) for irrigation in a dry coastal agricultural region in Eastern Saudi Arabia and its impact on groundwater resources. Field investigations were conducted in Qatif to collect water samples and field measurements. A multi-criteria approach was applied to evaluate the TWW's suitability for irrigation, including complying with Saudi Standards, the Irrigation Water Quality Index (IWQI), the National Sanitation Foundation water quality index (NSFWQI), and the individual irrigation indices. In addition, the impact of TWW on groundwater was assessed through hydrogeological and isotope approaches. The results indicate that the use of TWW in the study area complied with the Saudi reuse guidelines except for nitrate, aluminum, and molybdenum. However, irrigation water quality indices classify TWW as having limitations that necessitate the use for salt-tolerant crops on permeable and well-drained soils. Stable isotopic analysis (δ2H, δ18O) revealed that long-term irrigation with TWW affected the shallow aquifer, while deep aquifers were minimally impacted due to the presence of aquitard layer. The application of TWW irrigation has successfully maintained groundwater sustainability in the study area, as evidenced by increased groundwater levels up to 2.3 m. Although TWW contributes to crop productivity, long term agricultural sustainability could be enhanced by improving effluent quality, regulating irrigation practices, implementing buffer zones, and monitoring shallow groundwater. An integrated approach that combines advanced wastewater treatment methods, community involvement, regulatory oversight, and targeted monitoring is recommended to be implemented.

Enterococci pathways to coastal waters and implications of sea level rise

Highly urban coastal communities in low lying areas and with high water tables are vulnerable to sea-level rise and to corresponding increases in coastal groundwater levels. Stormwater conveyance systems are under increased risk. Rising groundwater levels affect the hydraulics of the stormwater system thereby increasing contaminant transport, for example the fecal indicator bacteria enterococci, to coastal waters. This study offers a unique opportunity to evaluate the impacts of increased contaminant transport on marine coastal environments. Here we assessed historic and recent coastal water quality, stormwater sampling data, groundwater monitoring and tidal elevations near the coastline, in the context of altered hydraulics within the system. Two pathways of enterococci to marine waters were identified. Direct discharge of contaminated stormwater runoff via the stormwater outfalls and tidally driven contaminated groundwater discharge. As sea level continues to rise, we hypothesize that a diminished unsaturated zone coupled with altered hydraulic conditions at the coastal groundwater zone will facilitate the transport of enterococci from urban sediments to the study site (Park View Waterway in Miami Beach, FL USA). We recommend improvements to the stormwater conveyance system, and maintenance of the sanitary sewer system to mitigate these impacts and minimize transport of enterococci, and other stormwater pollutants to coastal waters. The results of this study can be useful to interpret high enterococci levels in low lying coastal areas where groundwater is influenced by rising sea water levels.

Методология влияния свободной порозности и водоотдачи на процессы, происходящие в почвогрунтах оросительных каналов с земляным руслом

Purpose of the research: to consider the influence of free porosity and water loss on the filtration of water from channels with an earthen bed. Explore existing calculation methods taking into account the parameters of free porosity and fluid loss. Collect calculation material that can form the basis of a program for calculating the filtration of channels with an earthen bed, taking into account the factors influencing the first and second stages of filtration in the channels. Materials and research methods: The work used theoretical methods for calculating filtration in channels with an earthen bed, presented the calculation of the loss of flow rate Qf for filtration per 1 km of length with a steady free surface for different types of channel cross-sections, considered the basic formulas proving that water supply changes with changes in transverse cross-section of the canal, the change in the stability of the canal slopes is shown, a test calculation of the canal for filtration strength according to the maximum pressure gradients is presented, the need to compare the excess of the critical filtration pressure gradient with the permissible pressure gradient is considered. Results and its discussion. The relationship between the total, capillary and minimum moisture capacity and water yield in the thickness of soils is presented, the dependence of free porosity on the groundwater level, and the change in water permeability of soils over time are considered. As a result of the research, material was collected on the influence of free porosity and water loss on the movement of water in soils and the influence on the increase in groundwater levels in the zone of influence of canals, a methodology was presented for the influence of free porosity and water loss on the processes occurring in the soils of irrigation canals in an earthen channel, which will allow its use for modeling these processes on a computer.

Innovative groundwater management in industrial park: Optimization and modelling of extraction system

The research presented in this paper focuses on the optimization and modelling of an innovative groundwater extraction system and addresses the challenge of managing the increased groundwater level in Nitra Industrial Park, where the Land Rover Jaguar car manufacturer is located. The primary objective of this research was to determine the optimal pumping rate of the system, ensuring the maintenance of the groundwater level at the required elevation without depleting the surrounding water resources. To achieve this goal, a numerical groundwater modelling approach was utilized, employing the TRIWACO simulation package and the finite element method (FEM). The study involved various simulations under steady and unsteady flow conditions, using hydrological, geological and hydrogeological data, including the results of three proposed pumping tests conducted by INGEO, Ltd. Company, as well as measured groundwater level data from boreholes monitored by the Slovak Hydrometeorological Institute (SHMI). Implementing transient groundwater flow simulations considered the impact of a 1000-year flash flood wave (Q1000). This paper presents results of numerical modelling results, offering insights into maintaining the required groundwater elevation while considering key parameters and uncertainties for design purposes. Additionally, on-site optimization was performed to ensure efficient system operation and minimize associated costs. In conclusion, this research contributes to sustainable groundwater management in the Nitra Industrial Park, addressing the challenge of the increased groundwater level and providing valuable findings to optimize the extraction system’s performance.

A natural hydrogen seep in Western Australia: Observed characteristics and controls

Natural hydrogen (H2) is a promising resource for the energy industry’s transition to zero-carbon fuels. However, its extent and feasibility for exploitation remain unclear. A key step towards discovering subsurface dihydrogen accumulations is detecting H2 seeps. This study presents the first autonomous, multi-gas monitoring of a natural hydrogen seep in Australia, where dihydrogen, carbon dioxide, and hydrogen sulphide were measured together. The research revealed significant H2 seepage on the Yilgarn Craton in Western Australia, with seasonal fluctuations: high emissions after dry summers and reduced emissions following rainfall due to increased groundwater levels. Groundwater appears to act as a seasonal inhibitor to H2 seepage through the near subsurface potentially leading to false negatives in soil gas surveys post-rainfall and in low-lying areas. This work provides fundamental data for natural hydrogen exploration and therefore aids in the implementation of a large-scale hydrogen economy.

Spatiotemporal Variation and Long-Range Correlation of Groundwater Levels in Odessa, Ukraine

Increasing groundwater levels (GWLs) may become one of the most serious issues for the city of Odessa, Ukraine. This study investigated the spatial distribution characteristics and multifractal scaling behaviour of the groundwater-level/-depth fluctuations for a Quaternary aquifer in the city of Odessa using a geostatistical approach and multifractal detrended fluctuation analysis (MF-DFA). These two methods were applied to monthly GWL fluctuation time series from 1970 to 2020 to monitor 72 hydrogeological wells situated in different parts of the city of Odessa. The spatial distribution of the GWLs revealed an overall trend of decline and recovery from 1970 to 2020 in the study area, except for most of the southern region, where a persistent recovery of the groundwater depth was observed. The MF-DFA results suggest that the dynamics of the GWL fluctuations have multifractal characteristics in the Odessa area. In addition, both long-range correlations and fat-tail probability distribution contribute to the multifractality. However, long-range correlations among the fluctuations made a major contribution to the observed multifractality of the GWL fluctuation time series. The generalised Hurst exponents show a wide range of change (0.20 &lt; h(q) &lt; 2.85), indicating the sensitivity of the GWL fluctuations to changes in small-scale factors and large-scale factors. Regarding the long-range correlations of the GWL depths, the Hurst exponents (q = 2) demonstrated the positive persistence of groundwater-depth recovery in the southern region and the persistence of groundwater-depth variation in the other regions of the study area. The dynamic changes in the GWL depths in the Odessa area may be influenced by both natural and anthropogenic factors.

The potential of industrial green stormwater infrastructure to provide long-term supplementary flood mitigation for low-lying coastal cities under climate change

Coastal city flooding is projected to worsen in low-lying cities with climate change. Planners are concerned about the inadequacy of their current flood mitigation strategies, and the expense and risk of investing in expensive grey infrastructures, such as levees, under climate uncertainty. Implementing green stormwater infrastructure (GSI) on large privately-owned industrial land may be an attractive alternative; however, little is known about its potential for providing supplementary flood mitigation with climate change. Using Christchurch, New Zealand, as a case study, we applied hydrological modelling and spatial analysis to assess its potential to keep the impact of the increased rainfall intensities within the current flood protection capacity. Increasing groundwater levels due to rising sea levels were also considered to determine land capability for in-ground retention of stormwater. Findings demonstrate significant capability in four out of six catchments to reduce the impact of climate change–induced increased runoff volume to within the current flood protection level in the medium term (2030–2050). Two of the catchments also reduced runoff to this level in the long term (2080–2100), and under much larger storm events than the design storm, though not under all climate scenarios. Long-term flood mitigation capability can be provided where industrial land occupies a large proportion of a catchment’s area, is able to capture runoff from upstream, and where the high water table is deeper than 2 m. Industrial GSI has the potential to provide supplementary surface runoff containment through an adaptive flood mitigation planning strategy in response to unfolding climate change conditions.