Analysis of recharge by paddy field irrigation using 222Rn concentration in groundwater as an indicator

Hamada, Hiromasa; Komae, Takami

doi:10.1016/s0022-1694(97)00145-5

Cited by 18 publications

(4 citation statements)

References 5 publications

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“…Radon ( 222 Rn) concentration in water samples collected in 2007 and 2009 was measured using a liquid scintillation counter (Tri-Carb 2250CA, Packard BioScience, USA) after in situ extraction with toluene following the methods of Hamada and Komae (1998). The total error was less than 0.05 Bq l -1 .…”

Section: Analysesmentioning

confidence: 99%

“…The concentration of 222 Rn in groundwater leaches 98% of its value at secular equilibrium after three weeks underground. In general, 222 Rn concentration in groundwater is higher than that in surface water (Hamada and Komae 1998). 222 Rn is useful as an indicator to distinguish the impact of caves and caverns, because its concentration in the groundwater of caves and caverns is relatively low (e.g., Pane 1995).…”

Section: Introductionmentioning

confidence: 99%

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Groundwater flow and transport and potential sources of groundwater nitrates in the Ryukyu Limestone as a mixed flow aquifer in Okinawa Island, Japan

Yoshimoto

Tsuchihara

Ishida

et al. 2011

Paddy Water Environ

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We investigated the groundwater flow and the transport and potential source of groundwater nitrates in the typical karst setting of the Ryukyu Limestone aquifer in the southern part of Okinawa Island, Japan. Analysis of groundwater hydrographs indicated that this is a ''mixed flow'' aquifer with the coexistence of slow diffuse flow in the matrices and rapid conduit flow in the caves and caverns. This relationship is indicated by the travel time of groundwater flow: 70 days in the matrices of the aquifer and 6 days through the caves and caverns. The conduit flow system was also confirmed by the distribution of relatively low concentrations of 222 Rn near caverns. The sampling sites were categorized into upland field (UF) type and residential area (RA) type according to the land-use ratio on the upstream side with a 600-m influential radius, and cave and cavern (CC) type according to the hydrogeologic setting near two large caverns, even though the CC type should be categorized as the UF type from the viewpoint of land use. Cross plots of NO 3 -N versus SO 4 2-showed that the predominant source of UF groundwater nitrates was chemical fertilizer. A difference was observed in average d 15 N values between UF (8.9%) and RA (10.0%). On the other hand, the average d 15 N value for CC (10.5%) was similar to that for RA, indicating that CC nitrates were not related to the surrounding land use. This phenomenon is considered as evidence that CC groundwater nitrates were carried by rapid groundwater flow through caves and caverns from residential areas located higher upstream compared to the influential areas. According to previous studies, animal and human waste was considered the predominant sources of RA and CC groundwater nitrogen. The contribution ratio of chemical fertilizer (R CF ) was calculated using mass balance equations under assumed predictability. There was a relatively high correlation between the rate of upland areas and of residential areas and R CF . Average R CF for UF, RA and CC was 41, 27, and 25%, respectively.

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Section: Analysesmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Groundwater flow and transport and potential sources of groundwater nitrates in the Ryukyu Limestone as a mixed flow aquifer in Okinawa Island, Japan

Yoshimoto

Tsuchihara

Ishida

et al. 2011

Paddy Water Environ

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“…In karst aquifers, researchers have analyzed radon concentrations to understand the recharge dynamics of water passing through the soil layer to the saturated zone [8]. Additionally, groundwater and soil radon concentrations are measured during irrigated and non-irrigated periods in paddy fields, and the difference in the concentration values between groundwater and surface water is used to evaluate surface water infiltration into the aquifer [9]. Radon can also be used for estimating the probability of geophysical risk events such as volcanic activity and earthquakes [10][11][12].…”

Section: Introductionmentioning

confidence: 99%

Temporal and Spatial Variation of Radon Concentrations in Environmental Water from Okinawa Island, Southwestern Part of Japan

Nakasone

Ishimine

Shiroma

et al. 2021

IJERPH

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In this study, to get a better understanding in characterizing groundwater and ensure its effective management, the radon concentrations in water samples were measured through Ryukyu limestone in southern Okinawa Island, Japan. Water samples were collected from a limestone cave (Gyokusendo cave, dropping water) and two springs (Ukinju and Komesu, spring water), and the radon concentrations were measured by liquid scintillation counters. The radon concentrations in the samples from the Gyokusendo cave, and Ukinju and Komesu springs were 10 ± 1.3 Bq L−1, 3.2 ± 1.0 Bq L−1, and 3.1 ± 1.1 Bq L−1, respectively. The radon concentrations showed a gradually increasing trend from summer to autumn and decreased during winter. The variation of radon concentrations in the dripping water sample from the Gyokusendo cave showed a lagged response to precipitation changes by approximately 2–3 months. The estimated radon concentrations in the dripping water sample were calculated with the measured radon concentrations from the dripping water obtained during the study period. Based on our results, groundwater in the Gyokusendo cave system was estimated to percolate through the Ryukyu limestone in 7–10 days, and the residence time of groundwater in the soil above Gyokusendo cave was estimated to be approximately 50–80 days. This work makes a valuable contribution to the understanding of groundwater processes in limestone aquifers, which is essential for ensuring groundwater sustainability.

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“…In addition to the economic production functions for daily human staples, the ecological conservation of biodiversity and habitat is also another important consideration factor when considering paddy fields design (Adhikari et al, 2009). Furthermore, during the growing process, paddy field irrigation could be beneficial for groundwater recharge (Hamada and Komae, 1998; Ting et al, 2005), prevention of land subsidence (Don et al, 2006), flood mitigation (Yoshikawa et al, 2010; Steele et al, 2015), cooling the localized temperature (Lobell et al, 2008), and greenhouse gas reduction (Huang et al, 2006; Maraseni and Cockfield, 2012). Moreover, the paddy field could provide aesthetically pleasing landscape, fine leisure space and fresh air and could promote the associated living quality for humans.…”

Section: Introductionmentioning

confidence: 99%

Optimization of bund wall height and trigger depth for re‐irrigation in paddy field by deepwater ponding irrigation treatment

Huang

Chen

2020

Irrigation and Drainage

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This study develops two models and an algorithm to determine the optimal bund wall height of the paddy field and the trigger depth for re-irrigation, considering the benefits and costs of the transformation from shallow intermittent irrigation treatment to deepwater ponding irrigation. The models and algorithms are composed of: (i) a hydrologic model for ponding depth simulation in a paddy field; (ii) an optimization model for height design and depth determination in deepwater ponding irrigation; (iii) a real-coded genetic algorithm for solving the optimization model. The results show that the optimal bund wall height of the paddy field is 27.7 cm and the optimal discount ratio of reirrigation depth (i.e. trigger depth divided by the upper limit of ponding depth) is 0.008 in Taiwan, with a unit net benefit of US$18 500 ha‾¹. During the first crop-growing season (January to May) and the second (June to October), the benefit of groundwater recharge, flood mitigation, saved irrigation quantity and income of paddy rice of deepwater ponding irrigation is increased by 73, 13, 53 and 25% than those of shallow intermittent irrigation treatment, respectively. Furthermore, the total benefit of the second season is 16% better than that of the first. K E Y W O R D S deepwater ponding irrigation, paddy rice field, optimal bund wall height, trigger depth for reirrigation, genetic algorithm, tabu search Résumé Cette étude développe deux modèles et un algorithme pour déterminer la hau

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Analysis of recharge by paddy field irrigation using 222Rn concentration in groundwater as an indicator

Cited by 18 publications

References 5 publications

Groundwater flow and transport and potential sources of groundwater nitrates in the Ryukyu Limestone as a mixed flow aquifer in Okinawa Island, Japan

Groundwater flow and transport and potential sources of groundwater nitrates in the Ryukyu Limestone as a mixed flow aquifer in Okinawa Island, Japan

Temporal and Spatial Variation of Radon Concentrations in Environmental Water from Okinawa Island, Southwestern Part of Japan

Optimization of bund wall height and trigger depth for re‐irrigation in paddy field by deepwater ponding irrigation treatment

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