Climate change and groundwater resources in Thailand

The average temperature of Thailand is projected to increase by 2-3 °C, and the annual rainfall is projected to increase by 25% and up to 50% in certain areas. The climate change in future is expected to provide changes in hydrological cycle and therefore impacts the groundwater resources too. In this study, we analyzed the general climate change trends and reviewed the groundwater conditions of Thailand. The climate changes, hydrologic variability and the impact of climate change on groundwater sustainability are also discussed based on a national groundwater monitoring program. Currently, there are 864 groundwater monitoring stations and 1 524 monitoring wells installed in Thailand. Moreover, the impact of climate change on groundwater-dependent systems and sectors is also discussed according to certain case studies, such as saline water intrusion in coastal and inland areas. Managing aquifer recharge and other projects are examples of groundwater adaptation project for the future.

Application of Geophysical Logging and Straddle Packers for the Investigation of a Fractured Aquifer in a Contaminated Area by Chlorinated Solvents in Sao Paulo State, Brazil

The investigation of contaminated areas in fractured aquifers represents a great technical challenge, due to the frequent conditions of heterogeneity and anisotropy of these environments, which often make it difficult to identify and predict pathways of subsurface contamination. This work aims to contribute to the development of this subject, through the presentation of the results of an investigation in which geophysical logging tools and straddle packers were used, which allowed the development of a more suitable hydrogeological conceptual model of the study area. Two boreholes were drilled and geophysical logging (gamma, caliper and high resolution acoustic televiewer) were used for the geological-structural characterization of the aquifer. Heatpulse flowmeter and straddle packers were then used to obtain data on hydraulic potentials and flows and for the collection of discrete water samples for chemical analysis. Two types of gneiss rocks were identified below the weathering zone (thickness >30 m), one with predominance of mafic bands, more weathered and with a higher fracture density, up to 65 m, and another deeper one, with the predominance of felsic bands. Seven groups of fractures were defined, being those of Group 1, with low dip angles, the most frequent and important for flow until 65 m, and Group 2 (N to NE-SW with high dips to W and NW) more frequent in deeper felsic gneisses. Downward hydraulic potentials were identified down to 65 m and upward potentials from the bottom up to 65 m. A hydraulic test allowed identifying the occurrence of hydraulic connection between the shallow weathering zone and the underlying fractured aquifer.

Ranking the Suitability of Sub-watersheds for Ponding-Based Methods of Managed Aquifer Recharge in Lower Yom River Basin, Thailand

The study area is located in the Lower Yom River Basin covering an area of about 970 km^2 in the lower part of Northern Thailand, which is underlain by sequences of unconsolidated alluvial deposits derived from the Yom and Nan River floodplains. Groundwater has been heavily exploited largely for agriculture from the shallow gravel, sand and silt aquifer in the basin. Drastically declining water levels, up to 10 m in some areas, has been observed within the past decade, creating difficulties with lift irrigation for the local farmers. Therefore, the Department of Groundwater Resources, Thailand, considers that groundwater artificial recharge may be useful for recovering the static water levels within the most hydrogeological suitable areas. The objective of the paper is to rank the suitability of sub-watershed in the Lower Yom River Basin for conducting a pilot-scale testing of MAR （managed aquifer recharge） by ponding system. Hydrogeological and non-hydrogeological parameters were used to formulate the site selection criteria. Boolean logic and Fuzzy logic were used for delineating the 19 sub-watersheds in the Lan Ba watershed. Detailed hydrogeological investigations were conducted in the 10 most prospective sub-watersheds. Of these, the Nong Na 3 sub-watershed covering an area of about 500 hectares was determined to be the most appropriate site for the MAR pilot construction and testing.

Managed Aquifer Recharge Using Infiltration Pond： Case Study of Ban Nong Na, Phitsanulok, Thailand

The Upper Chao Phraya River Basin, Thailand, has been facing continuous groundwater level decreases due to over-extraction for irrigation. MAR （managed aquifer recharge） using infiltration pond was investigated and constructed. A recharge experiment at the pilot site at Ban Nong Na, Phitsanulok Province, was conducted during 2009 to 2011 to mitigate the declining shallow groundwater level. The HELP3 and MODFLOW models were applied to explore the current groundwater recharge. The MODFLOW was used to simulate the recharge mechanism of the experiment in the 1,260 m2 infiltration pond during July to November, 2010. The simulated results showed the groundwater influx and outflux for the year 2010 were 1.34 Mm3 1.57 Mm3, respectively. The annual shallow groundwater extraction was 1.40 Mm3 resulting in the groundwater system deficit of 0.23 Mm3 and causing groundwater level decline at the rate of 0.25 m/yr. The critical zone with groundwater level deeper than 8 m from the ground surface covers 19% of the study area of 4.12 km2 and it would be increased up to 85% within the next 10 years （2020）. To achieve the groundwater system balance, the deficit amount of 0.23 Mm3 is needed and six infiltration ponds are required.

Environmental Forensic Investigation in the Residential Neighborhood Volta Grande IV,Volta Redonda,RJ,Brazil,Using TPH and PAHs Analyses in Soil Samples

This article presents the results of a forensic investigation concerning the origin of hydrocarbons detected in the subsurface soil of the residential neighborhood Volta Grande IV, Volta Redonda, RJ, Brazil. Previous investigations identified several areas with concentrations of volatile organic compounds (VOCs) and polycyclic aromatic hydrocarbons (PAHs) above the Brazilian regulatory standards of CONAMA 420/2009 within the study area. Concern was raised that these hydrocarbons might be derived from local steel mill wastes. This forensic investigation determined that the VOCs in the residential soil are associated with gasoline and possibly diesel fuel oil releases into the subsurface soils that are not associated with the steel mill waste. The PAHs in residential subsurface soil generally fell below background concentrations and are likely associated with regional soot. The PAHs in the three samples with concentrations above background (out of a total of thirty-six samples) exhibit compositional features similar to coal byproducts, such as tar and coke, possibly attributable to the steel mill operation. This work discusses the geoforensic data and chemical signatures that support these findings.

Basic analysis of rock mechanical and thermal properties in South Korea

This study analyzed the mechanical and thermal properties of various rock types found in South Korea.The results showed that both igneous and metamorphic rocks possess higher strength compared to sedimentary rocks.The Young's modulus of rocks is dependent on the extent of weathering they have undergone.The average cohesion of granites was found to be relatively higher compared to other rock types,and their friction angle also exhibited a relatively high value with a considerable variance.The results of uniaxial compression strength testing with respect to depth revealed that rock strength generally increased with depth,however,there was a large variance in strength distribution in each depth interval.Based on these findings,it can be concluded that South Korea can also secure HLW disposal sites and facilities in terms of rock mechanics by using crystalline rocks,similar to countries such as Sweden and Finland where disposal facilities are being built.Regarding the thermal properties of rocks,they are influenced by the distribution of the parent rock.The thermal conductivity is highly concentrated in the southwest and central regions of South Korea,while the geothermal gradient is high in the northeast,west,and some parts of the southeast regions.The southeast region of Korea has a high geothermal heat flow,and some central northern regions also exhibit relatively high geothermal heat flow.In light of these distributional characteristics,it is crucial to continue conducting precise studies on the mechanical and thermal properties of rocks in the future disposal depths of spent nuclear fuel.