scholarly journals Groundwater Flow Modeling in the Malioboro, Yogyakarta, Indonesia

2018 ◽  
Vol 3 (1) ◽  
pp. 11
Author(s):  
Alwan Satapona ◽  
Doni Prakasa Eka Putra ◽  
Heru Hendrayana

Malioboro is a famous tourism area in Yogyakarta City, in which there aremany hotels and increases every years and this follows by the increasing needs of fresh water taken from underlying groundwater. The decreasing of groundwater table become a great issue on this area, therefore the objective of the research is to predict groundwater table change in the next 10 years due to increase abstraction of groundwater. To answer the mentioned objectives, field observation of dug wells and collection of secondary data of log bores also calculation of recharge and water abstraction are used to understand and build the conceptual model of local groundwater system. The prediction is done by conducting simulation on a numerical groundwater model by using MODFLOW. The local groundwater system consists of two aquifer layers; upper aquifer and lower aquifer which separated incompletely by clay layer. Simulation is conducting by distributing the groundwater pumping for domestic and non-domestic utilization by dug wells in the upper aquifer, whereas deep wells non-domestic utilization are applied only in the lower aquifer. Simulations are conducted twice for the recent day and the next ten years predictionof groundwater abstraction. In the case of groundwater abstraction in the next tenyears, dug wells abstraction and deep wells pumping are setting to 4727 m3/day and 1648 m3/day, respectively. The groundwater pumping rates is representing increase of groundwater withdrawal of users in the range only between 0.2–1.2 % per year compare to the recent condition. The simulation reveals change occur on groundwater table depth and pattern. In average, the groundwater table will decrease of about 0.25 meter.

Author(s):  
Filiz Dadaser-Celik ◽  
Mete Celik

Palas Basin is a semi-arid closed basin located in the Central Anatolia region of Turkey. The major economic activity in the basin is agriculture; therefore, both surface water and groundwater are used for irrigation. However, intensive use of water resources threatens the hydrologic sustainability of a lake ecosystem (Tuzla Lake) located in the basin. In this study, we analyzed the relationships between agricultural water uses in the Palas Basin and water flows to the Tuzla Lake using groundwater flow model developed with the FREEWAT platform. The model grid with 250 m x 250 m resolution was created based on the entire watershed. Two hydrostratigraphic units were identified. The source terms defined in the model were rainfall recharge and the sink terms were evapotranspiration and wells. The model was run for one year at steady state conditions. Three scenarios were simulated to understand the effect of groundwater use on the lake hydrology. The first scenario assumed that there was no groundwater abstraction. As the second and third water management scenario, the model was run with 50% less and %50 more groundwater abstraction than that of the reference conditions. The model successfully simulated the direction of groundwater flow and groundwater levels in the basin. Annual groundwater recharge was simulated as 5.27 million m3. Groundwater losses were due to pumping (1.49 million m3/yr), leakance to Değirmen River (2.25 million m3/yr) and seepage to Tuzla Lake (1.53 million m3/yr). Water flows to Tuzla Lake were significantly related to pumping rates. Increasing groundwater pumping rates reduces groundwater flows to Tuzla Lake and lowers lake water levels. No groundwater abstraction and reduction in groundwater pumping rates increase water flows to Tuzla Lake and cause higher water levels. This analysis showed that protection of hydrologic characteristics of Tuzla Lake is only possible with more control on groundwater abstraction.


Pollutants ◽  
2021 ◽  
Vol 1 (2) ◽  
pp. 66-86
Author(s):  
Simone Varisco ◽  
Giovanni Pietro Beretta ◽  
Luca Raffaelli ◽  
Paola Raimondi ◽  
Daniele Pedretti

Groundwater table rising (GTR) represents a well-known issue that affects several urban and agricultural areas of the world. This work addresses the link between GTR and the formation of solute plumes from contaminant sources that are located in the vadose zone, and that water table rising may help mobilize with time. A case study is analyzed in the stratified pyroclastic-alluvial aquifer near Naples (Italy), which is notoriously affected by GTR. A dismissed chemical factory generated a solute plume, which was hydraulically confined by a pump-and-treat (P&T) system. Since 2011, aqueous concentrations of 1,1-dichloroethene (1,1-DCE) have been found to exceed regulatory maximum concentration levels in monitoring wells. It has been hypothesized that a 1,1-DCE source may occur as buried waste that has been flushed with time under GTR. To elucidate this hypothesis and reoptimize the P&T system, flow and transport numerical modeling analysis was developed using site-specific data. The results indicated that the formulated hypothesis is indeed plausible. The model shows that water table peaks were reached in 2011 and 2017, which agree with the 1,1-DCE concentration peaks observed in the site. The model was also able to capture the simultaneous decrease in the water table levels and concentrations between 2011 and 2014. Scenario-based analysis suggests that lowering the water table below the elevation of the hypothesized source is potentially a cost-effective strategy to reschedule the pumping rates of the P&T system.


2012 ◽  
Vol 15 (2) ◽  
pp. 607-619 ◽  
Author(s):  
A. L. Yang ◽  
G. H. Huang ◽  
X. S. Qin ◽  
L. Li ◽  
W. Li

A simulation-based fuzzy optimization method (SFOM) was proposed for regional groundwater pumping management in considering uncertainties. SFOM enhanced the traditional groundwater management models by incorporating a response matrix model (RMM) into a fuzzy chance-constrained programming (FCCP) framework. RMM was used to approximate the input–output relationship between pumping actions and subsurface hydrologic responses. Due to its explicit expression, RMM could be easily embedded into an optimization model to help seek cost-effective pumping solutions. A groundwater management case in Pinggu District of Beijing, China, was used to demonstrate the method's applicability. The study results showed that the obtained system cost and pumping rates would vary significantly under different confidence levels of constraints satisfaction. The decision-makers could identify the best groundwater pumping strategy through analyzing the tradeoff between the risk of violating the related water resources conservation target and the economic benefit. Compared with traditional approaches, SFOM was particularly advantageous in linking simulation and optimization models together, and tackling uncertainties using fuzzy chance constraints.


2021 ◽  
Author(s):  
John P. Bloomfield ◽  
Mengyi Gong ◽  
Benjamin P. Marchant ◽  
Gemma Coxon ◽  
Nans Addor

Abstract. Water resource management (WRM) practices, such as abstractions and discharges, may impact baseflow. Here the CAMELS-GB large-sample hydrology dataset is used to assess the impacts of such practices on baseflow index (BFI) using statistical models of 429 catchments from Great Britain. Two complementary modelling schemes, multiple linear regression (LR) and machine learning (random forests, RF), are used to investigate the relationship between BFI and two sets of covariates (natural covariates only and a combined set of natural and WRM covariates). The LR and RF models show good agreement between explanatory covariates. In all models, the extent of fractured aquifers, clay soils, non-aquifers, and crop cover in catchments, catchment topography and aridity are significant or important natural covariates in explaining BFI. When WRM terms are included, groundwater abstraction is significant or the most important WRM covariate in both modelling schemes and discharge to rivers is also identified as significant or influential, although natural covariates still provide the main explanatory power of the models. Surface water abstraction is a significant covariate in the LR model but of only minor importance in the RF model. Reservoir storage covariates are not significant or are unimportant in both the LR and RF models for this large-sample analysis. Inclusion of WRM terms improves the performance of some models in specific catchments. The LR models of high BFI catchments with relatively high levels of groundwater abstraction show the greatest improvements, and there is some evidence of improvement in LR models of catchments with moderate to high discharges. However, there is no evidence that the inclusion of the WRM covariates improves the performance of LR models for catchments with high surface water abstraction or that they improve the performance of the RF models. These observations are used to formulate a conceptual framework for baseflow generation that incorporates WRM practices. It is recommended that information on WRM, particularly groundwater abstraction, should be included where possible in future large-sample hydrological data sets and in the analysis and prediction of BFI and other measures of baseflow.


2021 ◽  
Vol 13 (1) ◽  
pp. 43-66
Author(s):  
Ermias Hagos ◽  
Amare Girmay ◽  
Tesfamichael Gebreyohannes

This paper deals with the results of a pilot study conducted to estimate the shallow groundwater resource potential and irrigation capacity at the household level in Tahtay Koraro Woreda, northwestern zone of Tigray, Ethiopia. The potential evapotranspiration and actual evapotranspiration of the study area are estimated to be 1484 mm/year and 814 mm/year respectively. The runoff is approximately calculated to be 280 mm/year and the annual groundwater recharge is estimated to be 29 mm/year. The total annual groundwater abstraction for human, livestock, and irrigation is estimated to be 25 mm/year. It should be noted that the groundwater recharge rate is expected to remain constant while the total annual groundwater discharge is expected to increase from year to year. This relation when projected over a long period may result in a negative groundwater budget which can result in depletion of groundwater (lowering of groundwater levels), reduced baseflow to streams, and deterioration of water quality.  The computed values for hydraulic conductivity of the aquifers range from 1.63 m/day to 7.27 m/day with an average value of 4.9 m/day and transmissivity from 48.9 m2/day to 218.1 m2/day with an average value of 147.14 m2/day. The aquifers in the highly weathered basalt and highly weathered siltstone – sandstone intercalation have transmissivity values ranging from 99 m2/day to 218.1 m2/day with an average value of 157 m2/day and are grouped into the moderate potentiality aquifers category. The aquifers in the slightly weathered and fractured metavolcanics grouped under low potentiality based on the lower transmissivity values (<50 m2/day). The study area has low to moderate groundwater potentiality, hence, large-scale groundwater pumping is not possible. Therefore, the current activity of using hand dug wells for household-level irrigation is the best way of using groundwater for irrigation and other uses as well. Increasing the depth of the existing hand dug wells that are constructed in highly weathered basalt and highly weathered siltstone – sandstone intercalation can also enhance the yield of the hand dug wells. It is recommended to use water-saving irrigation technologies rather than increasing the number of wells. This will also help in increasing the irrigation area. Groundwater recharge enhancement structures such as trenches, percolation ponds, and check dams be constructed in scientifically selected localities to further enhance the groundwater potential.


2021 ◽  
Vol 920 (1) ◽  
pp. 012022
Author(s):  
F Baharudin ◽  
N Hamzah ◽  
I N Mohamad ◽  
Z Z M Zaki

Abstract Groundwater abstraction is a process of obtaining subsurface water sources for variety purpose of consumption. However, due to long and continuous pumping, the efficiency might decrease because of soil clogging. This decreased can be quantified and reflected as the change of hydraulic conductivity (K) values at the pumping site. This study aims to assess the variability of soil hydraulic conductivity at groundwater pumping site and also to study the effectiveness of vibration method to improve the hydraulic conductivity by comparing the result of before and after vibration is applied. The study was carried out by measuring the K values using slug test at wells MW01 and MW02 with two durations of vibration which were 45 minutes and 60 minutes. The result shows that values of hydraulic conductivity of the soil were found to have increased for both MW0l and MW02 wells. On first trial, the hydraulic conductivity increases for MW0l and MW02 are 16.7% and 39.3% while on second trial, the percentage increases for MW01 and MW02 are 54.3% and 11.1% respectively. Although the change for MW02 decreased for 60 minutes vibration, it can still be noted as there is a positive impact of vibration to the K value and further extensive data collection will be able to provide better assessment. Thus, it has been proven that the vibration method can be effective in reducing the soil clogging effect and also able to improve the hydraulic conductivity of the soil.


2020 ◽  
Vol 7 (2) ◽  
pp. 101
Author(s):  
Sugiarto Badaruddin ◽  
Akhmad Azis ◽  
Muhammad Fadhil Ashari ◽  
Miftahul Jannah ◽  
Ilham Ali ◽  
...  

In big cities, communities generally consume clean water from local water supply company which uses surface water sources. However, due to the limitations of the company in supplying water, particularly in the dry season, an alternative is required, such as using groundwater without causing over-exploitation. This study aims to determine the optimal rate of groundwater pumping in the coastal aquifer to avoid seawater up coning using SEAWAT V.4 numerical model. The research method was carried out using a GEO-7X GPS device to obtain coordinate's location, land elevation and observation well distance from the coastline. Secondary data in the form of aquifer thickness data and geological map of the site were obtained from previous studies. The salinity test results show that the average salinity value of the ten water samples from observation wells is 36.8 mg/l, which means that the water is categorized as non-saline water (freshwater). These data are in line with the groundwater utilization monitoring activity report of Makassar City Environment Office in 2018, which reported that Ujung Tanah and Wajo Districts were found to be free from seawater intrusion. Even so, the potential for seawater intrusion is still considered high because of the location of community groundwater wells are near from the coast. One of the efforts to prevent seawater up coning is by limiting groundwater pumping. From the numerical modeling results, it is found that the maximum groundwater discharge in the research site, namely P3 is 20% of total flow rate(0.3 m3/day), P5 is 20% (1.32 m3/day), P6 is 40% (0.52 m3/day) and P10 is 20%(0.63 m3/day).


Hydrology ◽  
2010 ◽  
pp. 227-228

2020 ◽  
Author(s):  
Jing Yang ◽  
Channa Rajanayaka ◽  
Lawrence Kees

&lt;p&gt;The Edendale terrace aquifer in Southland New Zealand has experienced a declining trend of groundwater table over the past two decades. Water abstraction has increased over this time and is associated with farming development, intensification and increased production of local industry. Coincident with an increase of groundwater abstraction is a decrease in annual precipitation. Current granted water allocation is ~55% of the allowable limit of 15% of land surface recharge. Determining the main driver of the declining groundwater table is a first step to improving the sustainability of water use in this area.&lt;/p&gt;&lt;p&gt;In this study, we combined a statistical method and physically based modelling method to analyse the main driving force. In the statistical method, the relationship between precipitation, groundwater abstract, and groundwater table over the past two decades have been analysed and the contributions from decreasing precipitation and increasing groundwater abstract were quantified. In the physically based method, a groundwater model (MODFLOW) was coupled with a hydrologic model (TopNet) to simulate the groundwater flow, and scenarios of groundwater abstract and precipitation were assessed using this coupled hydrologic model and groundwater model.&lt;/p&gt;&lt;p&gt;The modelling result above is used for sustainable water allocation management by the regional government, and this methodology can be used for groundwater management in other regions with declining groundwater table.&lt;/p&gt;


Water SA ◽  
2018 ◽  
Vol 44 (2 April) ◽  
Author(s):  
Muhammad Usman ◽  
Rudolf Liedl ◽  
Muhammad Arshad ◽  
Christopher Conrad

In recent years, extensive competition for groundwater use among different consumers has exploited major freshwater aquifers in Pakistan. There is an urgent need for appraisal of this precious resource followed by some mitigation strategies. This modelling study was conducted in the mixed cropping zone of the Punjab, Pakistan. Both remote sensing and secondary data were utilized to achieve objectives of this study. The data related to piezometric water levels, canal gauges, well logs, meteorological and lithological information were collected from Punjab Irrigation Department (PID), Water and Power Development Authority (WAPDA). Groundwater flow models for both steady and transient conditions were set-up using FEFLOW-3D. Water balance components and recharge were estimated using empirical relations and inverse modelling approaches. Both manual and automated approaches were utilized to calibrate the models. Moreover, sensitivity analysis was performed to see the response of model output against different model input parameters. Followed by calibration and validation, the model was run for different management scenarios, including lining of canal sections, minimization of field percolation, and change of groundwater abstraction. The study results show a drop in groundwater levels for almost all scenarios. The highest negative change was observed for the 4th scenario (i.e. 25% increase in groundwater pumping over a 10-year period), with a value of 3.73 m, by ignoring very wet summer and winter seasons. For normal weather conditions, the highest negative change was observed for the 4th scenario with a value of 2.91 m followed by 2.68 m for the 3rd scenario (i.e. 50% reduction in canal seepage and field percolation over a 10-year period). For very wet summer and winter seasons, only one positive change was observed, for the 5th scenario (i.e. 25% decrease in groundwater pumping during 10 years period), with a value of 1.17 m. The changes for all other scenarios were negative. The mitigation strategy may include less groundwater pumping, by supporting cultivation of low delta crops and adjusting cropping patterns considering canal water supplies. It is further suggested to support current modelling results by incorporating more detailed information on cropping and by exploring the effect of climate change.


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