Reduction In Groundwater Level Research Articles

Ecological-Based Mining: A Coal–Water–Thermal Collaborative Paradigm in Ecologically Fragile Areas in Western China

A substantial reduction in groundwater level, exacerbated by coal mining activities, is intensifying water scarcity in western China’s ecologically fragile coal mining areas. China’s national strategic goal of achieving a carbon peak and carbon neutrality has made eco-friendly mining that prioritizes the protection and efficient use of water resources essential. Based on the resource characteristics of mine water and heat hazards, an intensive coal–water–thermal collaborative co-mining paradigm for the duration of the mining process is proposed. An integrated system for the production, supply, and storage of mining companion resources is achieved through technologies such as roof water inrush prevention and control, hydrothermal quality improvement, and deep-injection geological storage. An active preventive and control system achieved by adjusting the mining technology and a passive system centered on multi-objective drainage and grouting treatment are suggested, in accordance with the original geological characteristics and dynamic process of water inrush. By implementing advanced multi-objective drainage, specifically designed to address the “skylight-type” water inrush mode in the Yulin mining area of Shaanxi Province, a substantial reduction of 50% in water drillings and inflow was achieved, leading to stabilized water conditions that effectively ensure subsequent safe coal mining. An integrated-energy complementary model that incorporates the clean production concept of heat utilization is also proposed. The findings indicate a potential saving of 8419 t of standard coal by using water and air heat as an alternative heating source for the Xiaojihan coalmine, resulting in an impressive energy conservation of 50.2% and a notable 24.2% reduction in carbon emissions. The ultra-deep sustained water injection of 100 m3·h−1 in a single well would not rupture the formation or cause water leakage, and 7.87 × 105 t of mine water could be effectively stored in the Liujiagou Formation, presenting a viable method for mine–water management in the Ordos Basin and providing insights for green and low-carbon mining.

Groundwater in India is Decreasing Because of Growing Urban Estates, Multiple Cropping Patterns and Excessive Water Use for Irrigation/agriculture

India is seeing a significant reduction in groundwater levels, attributed to changes in agricultural techniques, urbanization, and unsustainable water exploitation. This puts agriculture, the security of the water supply, and the daily lives of nearly 1.5 billion people in danger. The study explores the varied terrain of India, the different types of soil, and how heat waves and rainfall patterns are affected by climate change. The water crises in Chennai and Bengaluru highlight the need for strict water management techniques in the socioeconomic environment. In addition, the health consequences of tainted groundwater, which may contain dangerous substances like arsenic and chromium, demand prompt attention for appropriate disposal and surveillance to protect the public's health and welfare.

Overview Implementation of Precast U-Ditch Drainage Construction on Jalan Otto Iskandardinata

The increasing use of transportation infrastructure in Indonesia demands the development of facilities and infrastructure to enhance the quality of public services. Kalimantan Timur is a rapidly growing province. The rising population of Kalimantan Timur necessitates the construction of supportive facilities and infrastructure. Drainage refers to the action or process of draining/disposing of water, resulting from human activities like household wastewater, industrial wastewater, as well as natural processes such as rain, water accumulation, floods, and groundwater level reduction. The Drainage Project aims to improve the drainage system to reduce flood and waterlogging risks while preserving water quality, accommodating the growth of the population and the need for supporting infrastructure like housing, schools, and healthcare facilities. In the Drainage Development Project on Jalan Otto Iskandardinata, the precast concrete method with dimensions of 100x70x20 is used. The implementation of the U-Ditch Precast Drainage Project on Jalan Otto Iskandardinata is expected to alleviate flood issues. Before commencing the work, various tests such as the Slump Test, Compressive Strength Test, Hammer Test, and Tensile Strength Test are conducted to ensure compliance with the required specifications. Occupational Health and Safety (OHS) measures have been applied to the Drainage Project. Each stage of the project's implementation must be supervised by field inspectors to ensure the project runs smoothly and meets the required quality standards.

Machine learning-based techniques for land subsidence simulation in an urban area

Understanding and mitigating land subsidence (LS) is critical for sustainable urban planning and infrastructure management. We introduce a comprehensive analysis of LS forecasting utilizing two advanced machine learning models: the eXtreme Gradient Boosting Regressor (XGBR) and Long Short-Term Memory (LSTM). Our findings highlight groundwater level (GWL) and building concentration (BC) as pivotal factors influencing LS. Through the use of Taylor diagram, we demonstrate a strong correlation between both XGBR and LSTM models and the subsidence data, affirming their predictive accuracy. Notably, we applied delta-rate (Δr) calculus to simulate a scenario with an 80% reduction in GWL and BC impact, revealing a potential substantial decrease in LS by 2040. This projection emphasizes the effectiveness of strategic urban and environmental policy interventions. The model performances, indicated by coefficients of determination R2 (0.90 for XGBR, 0.84 for LSTM), root-mean-squared error RMSE (0.37 for XGBR, 0.50 for LSTM), and mean-absolute-error MAE (0.34 for XGBR, 0.67 for LSTM), confirm their reliability. This research sets a precedent for incorporating dynamic environmental factors and adapting to real-time data in future studies. Our approach facilitates proactive LS management through data-driven strategies, offering valuable insights for policymakers and laying the foundation for sustainable urban development and resource management practices.

The Effect of Groundwater Level Reduction by Installing Drainage Layers for Beach Deformation

The Effect of Groundwater Level Reduction by Installing Drainage Layers for Beach Deformation

Evaluating climate change impacts in a heavily irrigated karst watershed using a coupled surface and groundwater model

Study regionLower Apalachicola-Chattahoochee-Flint (ACF) River Basin of southeastern United States Study focusThe threats of climate change on the surface- and groundwater resources of the lower ACF River Basin of southeastern U.S. is an important concern for the long-term ecological as well as agricultural sustainability. This study developed a coupled SWAT-MODFLOW for the study region and evaluated the impacts of climate change projected under RCP4.5 and RCP8.5 emissions scenarios. New hydrological insights into the regionEvaluation of simulated streamflow and groundwater levels showed that SWAT-MODFLOW can adequately replicate the hydrology of a karstic watershed such as that present in the study domain even without the incorporation of conduit flows/karst features. Comparison to baseline conditions indicates a shift in the monthly streamflow pattern in the region with a reduction from April to June and increases in the rest of the year under future climate. The region will also likely see an increase in low-flow as well as high-flow events, thus increasing streamflow variability in the region. More frequent low flow conditions in the future can lead to increased drying of ephemeral streams threatening the ecological sustainability of the region due to habitat loss. This, along with the projected reduction in groundwater levels can lead to increased stress on water resources of the region for irrigation, thus threatening the agriculture sustainability and increasing water conflict between the neighboring states.

Effect of downward seepage on turbulence and morphology in mobile boundary sinuous channel

The porous boundary of alluvial channels allows water to interact with the surrounding groundwater. With reduction in groundwater level, transfer of water from the main channel to the groundwater is significant and referred to as downward seepage. The action of downward seepage causes morphological alteration along the sinuous alluvial channel. Laboratory experiments were conducted for no-seepage and seepage conditions to study the effect of downward seepage on turbulence and bed morphology in rectangular and trapezoidal sinuous channels. The deformation along the streambed and bank of the sinuous channels showed remarkable alterations with seepage. Downward seepage caused excess sediment transport in the sinuous channels showing high erosion along banks and streambed. With increased flow rate and downward seepage, prominent depositionalzones near inner region and erosion zones near outer region of the bend were observed in sinuous channel with rectangular cross section. Sinuous channel with trapezoidal cross section showed less morphological change as the side slope was almost equal to the angle of repose of the sand. However, with the application of downward seepage, the streambed of the channel has lowered in elevation, indicating sediment transport. Mean streamwise velocity at the center of the bend showed an average percentage increase in 26% in the rectangular channel and about 20% in the trapezoidal channel with downward seepage. The Reynolds shear stress estimated with downward seepage has increased near the channel bed, indicating high momentum flux. Higher bed shear stress was indicated near the channel bed with downward seepage, which results in downstream sediment transport.

Predicting Groundwater Level Using Climate Change Scenarios in the Southern Part of Mali

Groundwater is mainly demanded in all the activities for the population of the southern part especially in the Koda catchment, the studied area. These resources are affected by various factors especially climate change. Therefore, knowing the impact of projected climate change on groundwater recharge is an important issue for water resources management, especially for those responsible for the Koda catchment. In this work, the impact of climate change on groundwater resources in the study area in Mali, West Africa is investigated. The Hydrogeological modeling was performed using the Gardenia model, and the monthly precipitation and temperature data were used as the Baseline. These data considered the past 30-year period (1987-2016) and the projections for the next 30 years (2021-2050). Projected precipitation and air temperatures, extracted from the Rossby Centre regional Atmospheric climate model (RCA 4) statistically downscaled from the GCM-IHEC-EC-EARTH and the GCM-MPI-M-MPI-ESM-LR under the Representative Concentration Pathways RCP 4.5 and RCP 8.5 and corrected with the Multiscale Quantile Mapping bias correction method, were used as input data to the gardenia model. Potential evapotranspiration (PET) values estimated from Blaney Criddle method and groundwater levels measured in three piezometers were used to calibrate the Gardenia model. The outputs display the reduction of groundwater level in the three piezometers in the Koda catchment for all the two Regional Climate Models (RCMs) during the periods of rainy season from July to October. From the results of GCM IHEC-EC-EARTH, the projected decline in GWL reaches 1.09 m for the RCP 4.5 and it up to 1.26 m for the RCP 8.5 in the study area while the GCM MPI-M-MPI-ESM-LR presentes the decline in groundwater level (GWL) during winter season from about 0.62 m for the RCP 4.5 up to 1.93 m for the RCP 8:5. Both RCMs project a reduction trend of groundwater recharge over time. It is noticeable that this decline is greater in RCP8.5 for all the three piezometers. The results also show that the average groundwater recharge (90 mm) in the future (2021-2050) is lower (180 mm) than that of the current drought (1987-2016), which could lead to severe drought events. The projected impacts of climate change would have a significant impact on groundwater in the period of 2029-2039; this situation could have a negative impact the socioeconomic activities especially on agriculture, which depends on water resources. The results will help also to take some adaptation measures to climate change, the famers could have a possibility to know the period of groundwater recharge where they have more water infiltration therefore, where to seek crops that need less or more water. The study area presents numerous potential of groundwater, the results could be a tool for groundwater management and to determine the favorable sites to implant new boreholes.

Assessment of groundwater quality and its controlling processes in Bemetara District of Chhattisgarh State, India

Groundwater withdrawal at very fast rate poses threat on existing groundwater resources in different parts of the world. This reduction in groundwater levels significantly disturbed the natural aquifer flow rate and thereby different hydrogeochemical processes, which may further impair the groundwater quality. The groundwater quality in rural area of Chhattisgarh State is degraded, and the problem of saline water poses health risk to people. In this research investigation, suitability of groundwater of Bemetara District, Chhattisgarh, India, has been evaluated for drinking purpose through water quality index (WQI) method and principal component analysis (PCA). Total 116 groundwater samples were collected during the pre-monsoon (June 2019) and post-monsoon season (December 2019) and analyzed for physicochemical parameters. Total dissolved solids ranged from 250 to 10,440 mg/L and 289 to 3583 mg/L during pre-monsoon and post-monsoon, respectively, and 55% of the total samples exceeded acceptable BIS limit in pre-monsoon, while about 66% samples exceeded in post-monsoon season. SO42− concentrations varied from 3 to 5734 mg/L during pre-monsoon and 4.5 to 2002 mg/L during post-monsoon, respectively. Total 28% samples in pre-monsoon and 18% samples in post-monsoon season exceeded the maximum permissible BIS limit (400 mg/L) of SO42− ion in the study area. On the basis of WQI, the quality of groundwater varies from “Excellent water” to “Good water” category. The groundwater of northeastern part of the district is not suitable for drinking, and therefore, it is recommended to treat this groundwater before human consumption with special reference to SO42− contamination. PCA inferred that four components are sufficient to explain the variance in chemistry of groundwater that is mainly governed by dissolution of gypsum mineral, other rock–water interaction and anthropogenic activities. Further, water quality was improved in the direction of groundwater flow in the study area, establishing a direct relationship between groundwater flow and water quality of the Bemetara District. This study provides very useful database to design sustainable groundwater management plan for the district.

Investigation of hydrological processes and the impacts of Acacia mearnsii plantations on groundwater in secondary aquifers: Case study at the two-stream research catchment, South Africa

Study regionTwo-Streams catchment, KwaZulu-Natal Midlands, South Africa. Study focusThe impacts of Acacia mearnsii plantations on hydrological processes including groundwater is investigated using the Two-Streams experimental catchment as a case study site. Integrated hydrological, hydrogeological, hydrochemical and environmental isotope methods were adopted. Groundwater recharge is estimated using the chloride mass balance (CMB) method, and baseflow is separated using digital filters and δ18O isotope approaches. The direct and indirect impacts of the tree stands on groundwater including on recharge, groundwater level and baseflow are assessed. New hydrological insights for the regionSystematic analyses of all the hydrological data show that direct groundwater uptake by tree roots at the Two-Streams catchment would not be possible due to limiting root depths. However, there is clear evidence on the impacts of the tree stands on groundwater levels and baseflow at the study site. Thus, in instances where the regional groundwater is not available for direct abstraction by tree roots, trees can have considerable impacts on groundwater by extracting water from the unsaturated zone, reducing recharge to aquifers, without having direct access to the groundwater proper. The impact of Acacia mearnsii plantations on groundwater which are observed in terms of reductions in groundwater recharge and consequent reduction in groundwater levels and baseflow starts to be observed on average six years after planting.

Utilization of crushed M−Sandy soil as an advanced sustainable construction material in reinforced concrete structures

With the increasing demand of high quality infrastructure, the lack of conventional material in cities becomes the main problem. Due to this limitation in conventional material such as ordinary sand that is excavated from the river and harmful for the environment due to the reduction in ground water level, can be partially/fully replaced by M−Sand/Crushed stone rub down as an economic and ecological alternative for sustainable concrete structures. The use of M−Sand is a great effort towards sustainable enlargement in India. The life of a structure is affected by various parameters i.e. moisture content, free surface moisture (real time sample received in the lab), saturated surface dry (SSD), specific gravity, grain size analysis (to find out the sand zone), workability, water-cement ratio, impact value of aggregates etc. In this situation, while code provisions are also not available for M−Sand, a design parametric study has been conceded in the laboratory with respect to all necessary parameters for M−30 grade of concrete with different percentages of Manufactured-Sand which highly affects the design mix of concrete. In this article river or natural sand has been replaced fully and partially by M−Sand/Crushed sand likewise 0.0%, 10%, 40%, 45%, 50%, 55%, 65%, 75%, 85% & 100%. An advanced design mix procedure has been initialized here by using British codes, ACI & IS. It has been observed in the current research that most of the properties of River/Natural Sand and M−Sand/Crushed Sand are similar and it is also concluded that natural sand is able to be partially or full replaced by Manufactured sand as an economical substitute including sustainable construction material in Civil Engineering Construction era 4.0:Janpad Abhiyantriki (Civil Engineering).

The Effects of Urbanization on Reduction of Groundwater Level and Changes in Vegetation and Surface Temperature in Iran’s Desert Areas (Case Study: Yazd Province)

The Effects of Urbanization on Reduction of Groundwater Level and Changes in Vegetation and Surface Temperature in Iran’s Desert Areas (Case Study: Yazd Province)

Study of the drought status and its impact on groundwater resources: Case study, Hamadan, Iran

In recent year's climate changes account for extreme droughts, and one of the consequences of the drought is the reduction in groundwater levels. The present study was conducted to evaluate the drought status and its impact on the groundwater resources of Hamadan, Iran. This descriptive study data were collected from Water Affairs departments from 1987 to 2011. The study of the rainfall patterns over the past 25 years shows the large fluctuations in rainfall. The consequence of indiscriminate depletion of underground water resources is creating about 19 sinkholes in the plains. Over the past 50 years, about 320 villages have been uninhabited and the drinking water for 100 villages was supplied by tankers. Digging the illegal wells, uncontrolled exploitation of groundwater that cannot be replenished by recharge, uncontrolled exploitation of groundwater by the Shahid Mofateh power plants, unfavorable spatial and temporal distribution of rainfall, and lack of modern irrigation methods are responsible for the recent drought in Hamadan.

Wildfire Impacts on Groundwater Aquifers: A Case Study of the 1996 Honey Boy Fire in Beaver County, Utah, USA

It is well known that wildfires destroy vegetation and form soil crusts, both of which increase stormwater runoff that accelerates erosion, but less attention has been given to wildfire impacts on groundwater aquifers. Here, we present a systematic study across the contiguous United States to test the hypothesis that wildfires reduce infiltration, indicated by temporary reductions in groundwater levels. Geographic information systems (GIS) analysis performed using structured queried language (SQL) categorized wildfires by their proximity to wells with publicly available monitoring data. Although numerous wildfires were identified with nearby monitoring wells, most of these data were confounded by unknown processes, preventing a clear acceptance or rejection of the hypothesis. However, this analysis did identify a particular case study, the 1996 Honey Boy Fire in Beaver County, Utah, USA that supports the hypothesis. At this site, daily groundwater data from a well located 790 m from the centroid of the wildfire were used to assess the groundwater level before and after the wildfire. A sinusoidal time series adjusted for annual precipitation matches groundwater level fluctuations before the wildfire but cannot explain the approximately two-year groundwater level reduction after the wildfire. Thus, for this case study, there is a correlation, which may be causal, between the wildfire and temporary reduction in groundwater levels. Generalizing this result will require further research.

Assessment of impact in groundwater levels and stream-aquifer interaction due to increased groundwater withdrawal in the lower Apalachicola-Chattahoochee-Flint (ACF) River Basin using MODFLOW

Study regionLower Apalachicola-Chattahoochee-Flint (ACF) River Basin, southeastern United States (U.S.). Study focusExcessive groundwater withdrawal for irrigation from the Upper Floridan Aquifer is an important issue in the lower ACF River Basin as it has led to decline in groundwater levels as well as reduction in baseflows. Since the withdrawal is projected to further increase in the future, this study evaluated the impacts of the projected increase in irrigation on the groundwater levels as well as the stream-aquifer flux in the region. The study also identified regions that are most important for groundwater recharge. New hydrological insights into the regionEvaluation of the geohydrologic zones identified Upland Instream Karst as the most sensitive zone for recharge into the aquifer while zones in the region where the aquifer thickness was comparatively lower and close to the land surface was generally identified as sensitive. Simulation of the projected irrigation scenario predicted a reduction in groundwater levels by as much as 2.38 m, while a general reduction was predicted in much of the model domain. Large groundwater level reductions were mostly predicted in regions where the aquifer is comparatively thinner. Evaluation of the changes in stream-aquifer flux showed that flux reduced by as much as 33 % with large reductions predicted in the Lower Flint and Kinchafoonee watersheds. This study also helped identify localized zones and stream sections most susceptible to the impacts of increase in irrigation.

Failure criterion for concrete shafts in deep alluvium zones based on plastic ultimate strain and its application

The failure of vertical concrete shafts in the deep alluvium zones is always a troublesome technical problem in coal mines. There is lack of practical failure criteria for such shafts. Therefore, the method of establishing failure criteria of shafts based on the method of ultimate strain was proposed. By regarding concrete as a frictional geomaterial, the formula for the plastic ultimate strain of concrete was constructed according to the theory of generalised plastic mechanics. Furthermore, the ultimate strain when concrete failure was determined using numerical limit analysis method. The numerical limit strain analysis method can be used as a quantitative failure criterion for a concrete shaft. It can directly determine the limit state and failure position. By exploring the shaft deformation during the reduced groundwater level of quaternary aquifers by applying numerical limit analysis method, the failure procedure of concrete shaft was reproduced. It was revealed that the damage to the soil around the shaft preceded that to the shaft; the reduction in groundwater level of aquifers can damage the shaft, while the stress-relief groove delays the failure of the shaft and shifts the failure zone to a greater depth. On condition that water level decreased by 25 m, the sand layer at a burial depth of 158–174 m was damaged; in the case that water level was reduced by 27 m, the shaft at a burial depth of 181–182 m was damaged. After setting a stress-relief groove on the shaft, failure occurred when the groundwater level was decreased by 38 m, implying that the stress-relief groove can release the vertical stress on the shaft.

A Spatial Non-Stationary Based Site Selection of Artificial Groundwater Recharge: a Case Study for Semi-Arid Regions

In this study, a methodology was developed for AGR assessment, including site selection, non-stationary kriging, numerical modeling, and the long-term supply and demand sustainability. To achieve this, spatial variations maps of effective parameters were prepared using kriging techniques along with the Fuzzy logic method and GIS analytical functions for AGR site selection. To estimate how AGR is changing the water balance in the region, the Soil Water Assessment Tools (SWAT) hydrological model was coupled with an in house 2-D finite difference groundwater model. Based on the SWAT model results, by applying AGR, infiltration increased dramatically from 101 to 146 mm. In order to improve the model’s accuracy, transmissivity was regionalized through non-stationary kriging by splitting the region into sub-regions where the characteristics of each variogram are different. By using non-stationary kriging, the statistic R2 from single variogram to multiple variograms increased from 0.27 to 0.95, and the groundwater level was improved by 15%. Furthermore, for evaluating the sustainability of water resources, an index called Planning for Sustainable Index (PSUI) was utilized to measure AGR effects. PSUI, after applying AGR without changing in water withdrawal, was increased from 0.11 to 0.17 during 27-years time horizon. The case study is the aquifer in Qorveh Dehgolan sub-basin in Kordestan province, Iran. The results indicate that by applying AGR to the region, the rate of groundwater level reduction would decrease significantly for about 30%. However, for preventing the groundwater depletion, AGR should be accompanied by 50% reduction in withdrawals/pumping. The results show the significant value of utilizing a platform to assess the attributes and benefits of AGR. The proposed algorithm can be used for other geographical settings.

LAND SUBSIDENCE ANALYSIS OBSERVED BY PS-INSAR METHOD IN SOUTHERN PART OF BALI, INDONESIA (A CASE STUDY OF DENPASAR AND BADUNG AREA)

The utilization of groundwater unwise leads to problems for the life of sentient beings. The majority of environmental damage, mainly by groundwater utilization, is done or caused by human activities. The land subsidence, drought, seawater intrusion are some examples of damage caused by groundwater utilization unwise. This research aims to estimate land subsidence in southern Bali and analyze groundwater level reduction with land subsidence. The PS-InSAR technique to monitor land subsidence has been carried out in several regions in Indonesia and other countries. In this study, 38 images of Sentinel-1 taken from February 2015 to December 2018 are used to analyze the PS-InSAR technique. Land subsidence is found in Denpasar Utara district and Kerobokan district with deformation in -8 mm to -19 mm and velocity up to -5 mm/year. The utilization of groundwater causing land subsidence in Southern Bali is no significant relationship with coefficient correlation 0,16 and influenced only 2,7%. Limited groundwater data also influences the correlation between groundwater utilization and the occurrence of land subsidence.
 Keywords: Land Subsidence; Sentinel-1A; PS-InSAR; Southern Bali.

Proglacial groundwater storage dynamics under climate change and glacier retreat

AbstractProglacial aquifers are an important water store in glacierised mountain catchments that supplement meltwater‐fed river flows and support freshwater ecosystems. Climate change and glacier retreat will perturb water storage in these aquifers, yet the climate‐glacier‐groundwater response cascade has rarely been studied and remains poorly understood. This study implements an integrated modelling approach that combines distributed glacio‐hydrological and groundwater models with climate change projections to evaluate the evolution of groundwater storage dynamics and surface‐groundwater exchanges in a temperate, glacierised catchment in Iceland. Focused infiltration along the meltwater‐fed Virkisá River channel is found to be an important source of groundwater recharge and is projected to provide 14%–20% of total groundwater recharge by the 2080s. The simulations highlight a mechanism by which glacier retreat could inhibit river recharge in the future due to the loss of diurnal melt cycling in the runoff hydrograph. However, the evolution of proglacial groundwater level dynamics show considerable resilience to changes in river recharge and, instead, are driven by changes in the magnitude and seasonal timing of diffuse recharge from year‐round rainfall. The majority of scenarios simulate an overall reduction in groundwater levels with a maximum 30‐day average groundwater level reduction of 1 m. The simulations replicate observational studies of baseflow to the river, where up to 15% of the 30‐day average river flow comes from groundwater outside of the melt season. This is forecast to reduce to 3%–8% by the 2080s due to increased contributions from rainfall and meltwater runoff. During the melt season, groundwater will continue to contribute 1%–3% of river flow despite significant reductions in meltwater runoff inputs. Therefore it is concluded that, in the proglacial region, groundwater will continue to provide only limited buffering of river flows as the glacier retreats.

Modeling Green Roof Potential to Mitigate Urban Flooding in a Chinese City

The Middle and Lower Reaches of the Yangtze River (MLRYR) region, which has humid subtropical climate conditions and unique plum rain season, is characterized by a simultaneous high-frequency urban flooding and reduction in groundwater levels. Retrofitting the existing buildings into green roofs is a promising approach to combat urban flooding, especially for a densely developed city. Here, the application potential of the Green Roof System (GRS) and the Improved Green Roof System (IGRS) designed to divert overflowing water from green roofs to recharge groundwater were analyzed in a densely developed city, Nanchang, China. For the first time, the influence of GRS on the hydraulic condition of Combined Sewage System/Storm Water System (CSS/SWS) is analyzed, which is a direct reflection of the effect of GRS on alleviating urban flooding. The simulation results show that GRS can retain about 41–75% of precipitation in a 2-hour timescale and the flooding volumes in the GRS/IGRS region are 82% and 28% less than those of the Traditional Roof System (TRS) in 10- and 100-yr precipitation events, respectively. In the continuous simulations, GRS also enhances Evapotranspiration (ET), which accounts for 39% of annual precipitation, so that reduces the cumulative surface runoff. Considering the IGRS can provide more hydrological benefits than the GRS under the same climate conditions, we may conclude that the widespread implementation of both the GRS and the IGRS in Nanchang and other densely developed cities in the MLRYR region could significantly reduce surface and peak runoff rates.