Multiple-indicator study of groundwater flow and chemistry and the impacts of river and paddy water on groundwater in the alluvial fan of the Tedori River, Japan

Abstract

To investigate the source, flow paths, and chemistry of rich resources of high‐quality, shallow groundwater in the alluvial fan between the Tedori and Sai rivers in central Japan, we analysed stable isotope ratios of H, O, and Sr and concentrations of major dissolved ions and trace elements in groundwater, river water, and paddy water. The 87Sr/86Sr ratios of the groundwater are related to near‐surface geology: groundwater in sediment from the Tedori River has high 87Sr/86Sr ratios (>0.711), whereas that from the Sai River in the north of the fan has low 87Sr/86Sr ratios (<0.711). δ2H and δ18O values and 87Sr/86Sr ratios indicate that groundwater in the central and southern fans is recharged by the Tedori River, whereas recharge in the north is from the Sai River. Mg2+, Ca2+, Sr2+, HCO3−, and SO42− concentrations and δ2H and δ18O values in the groundwater are high in the central fan and, except for the northern area, tend to increase with distance from the Tedori River. There are linear relationships between 87Sr/86Sr ratio and the reciprocal concentrations of Sr2+, Mg2+, and Ca2+. These geochemical characteristics suggest that as groundwater recharged from the Tedori River flows towards the central fan, it mixes with waters derived from precipitation and paddy water that have become enriched in these components during downward infiltration. These results are consistent with our hydrological analysis and numerical simulation of groundwater flow, thus verifying the validity of the model we used in our simulation of groundwater flow. Copyright © 2016 John Wiley & Sons, Ltd.

Global Isotope Hydrogeology―Review

“…River water infiltration provides considerable groundwater recharge to some aquifer systems. Some works have identified groundwater δ 18 O and δ 2 H values that are similar to those characterizing nearby river(s), implying river waters may replenish these aquifers (e.g., Ali et al, ; Baskaran et al, ; Darling et al, ; Iwasaki Yoshioka et al, ; Kebede et al, ; Leontiadis et al, ; Ma, Jin, et al, ; Navada et al, ; Shamsuddin et al, ). Other studies have compared precipitation, groundwater, and river water isotope compositions and concluded stream waters do not recharge the aquifer (e.g., Baganza River, Italy—Deiana et al, ).…”

Statistical evaluation of a long‐memory process using the generalized entropic value‐at‐risk

“…The study area is Tedori River in Ishikawa Prefecture, Japan (Figure 3). The main channel of Tedori River starts in the Hakusan Mountains at an elevation of 2702 m. The river channel has a length of 72 km and a basin area of 807 km 2 , and it pours into the Sea of Japan (Iwasaki Yoshioka et al, 2016). The alluvial fan of the river has an area of 170 km 2 , which is covered by paddy fields.…”

Impacts of High-Concentration Turbid Water on the Groundwater Environment of the Tedori River Alluvial Fan in Japan

“…Maruyama et al [7] and Fujihara et al [8] conducted comprehensive studies on the mechanisms of snow accumulation and snowmelt in this basin. Furthermore, concerning the Tedori River alluvial fan, Iwasaki et al [9] and Yoshioka et al [10,11] analyzed the characteristics of the groundwater within the alluvial fan, utilizing data on groundwater levels, water quality, stable isotopic ratios and so on. Maruyama et al [12] provided insights into the water balance within alluvial fans, whereas Yoshioka et al [13] employed a 3D groundwater flow model (MODFLOW) to simulate groundwater systems under climate change conditions.…”