Estimation of groundwater recharge in a shallow sandy aquifer using unsaturated zone modeling and water table fluctuation method

The Jakarta Groundwater Basin is one of the groundwater basins with the highest development, economic, and business activities in Indonesia. Groundwater damage has become a major growing issue in the Jakarta groundwater basin. Intensive development has led to the overuse of groundwater in this basin. Efforts are needed to manage, protect, and conserve groundwater in this basin to support the development and economic activities sustainably. Jakarta, as the capital city of Indonesia, is located in the groundwater basin. Groundwater sustainability is determined by the amount of groundwater recharge in those basins, so knowledge of groundwater recharge is important. Groundwater is an important part of a hydrological cycle, and groundwater recharge ensures groundwater sustainability in some areas. This study aims to estimate groundwater recharge in the Jakarta groundwater basin using the water budget and water table fluctuation method. The water budget method used is Thornthwaite, Dingman, and Edijatno-Michel. The Water Table Fluctuation methods used are Dellin and Delottier. Analysis of the amount of groundwater recharge estimation is carried out using the ESPERE Version 2 software. Output data is then further analyzed using descriptive and inferential statistical approaches to determine whether there is a difference in groundwater recharge amount based on the water budget and water table fluctuation. The results show that groundwater recharge based on water budget methods is 209–885 mm/year. The estimation of the largest amount of recharge was obtained using the Edijatno-Michel approach. The smallest amount of recharge was estimated using the Dingman-Hamon method. The average recharge of groundwater in Tanjung Priok is 305 mm/year, Kemayoran is 209 mm/year, and Bogor is 885 mm/year. Only 8–15 % of the annual rainfall that converted into groundwater recharge at the study area. Based on the analysis using the water table fluctuation method, groundwater recharge in this basin has a value of 240 mm/year. The variation of the amount of groundwater recharge is caused by the pros and cons of each method. Apart from that, geological factors, land use/land cover factors, and climatic variations in this basin can affect the research results. By considering the amount of groundwater recharge, groundwater management in the Jakarta groundwater basin needs to be carried out for harmonious development and groundwater conservation.

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Estimating the Temporal Distribution of Groundwater Recharge by Using the Transient Water Table Fluctuation Method and Watershed Hydrologic Model

Applied Engineering in Agriculture ◽

10.13031/aea.13376 ◽

2021 ◽

Vol 37 (1) ◽

pp. 95-104

Author(s):

Il-Moon Chung ◽

Youn Jung Kim ◽

Nam Won Kim

Keyword(s):

Groundwater Recharge ◽

Water Table ◽

Temporal Distribution ◽

Jeju Island ◽

Specific Yield ◽

Recharge Rate ◽

Water Table Fluctuation ◽

Water Table Fluctuation Method ◽

Reaction Factor ◽

Fluctuation Method

HighlightsThe transient water table fluctuation method (TWTFM) is revisited.A novel application of linking SWAT model and TWTFM is suggested.A method is proposed to estimate daily groundwater recharge distribution.The method is demonstrated for the Jeju Island in Korea.Abstract. Estimating groundwater recharge remains a difficult but necessary task as part of managing available groundwater supplies. For example, the average groundwater recharge rate of Jeju Island is 54%, which is considerably higher than the inland recharge rate (~15%) in Korea. Although groundwater is the main water source of this and many other islands, quantifying temporal groundwater recharge for water resources planning remains difficult. To estimate groundwater recharge based on rainfall, a simple and straightforward method is proposed that uses an application of the Transient Water Table Fluctuation Method (TWTFM) linked with the Soil and Water Assessment Tool (SWAT). By using the computed annual percolation from the SWAT as input, two parameters (reaction factor and specific yield) could be estimated by assuming that the sum of daily recharge via the TWTFM was approximately equal to the annual percolation near the water table. This methodology was applied to the Hancheon watershed of Jeju Island, South Korea. Runoff time series data for two years (2009 and 2010) were used to calibrate SWAT and another two years of data were used to validate computed discharges from SWAT. For the calibration of the combined SWAT and TWTFM model, groundwater level data from 2009 and 2010 were used, and then data from 2011 and 2012 were used to predict groundwater recharge using the calibrated TWTFM parameters. The proposed methodology can be used as an efficient tool for estimating the temporal distribution of groundwater recharge using only groundwater data and the annual percolation rate. This methodology can be beneficial for regions where the vadose zone depth is deeply formed and temporal recharge predictions are essential for water management. Keywords: Reaction factor, Specific yield, SWAT, Transient water table fluctuation method (TWTFM).

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