Managed Aquifer Recharge (MAR) in areas used for agricultural purposes: the Rye Island pilot study

For a long-term retention of water in aquifers and its subsequent use in drier or heavier demand periods, the Managed Aquifer Recharge (MAR) techniques are studied and implemented in 4 pilot areas of the DEEPWATER-CE project. In Slovakia, the pilot study is situated in the Rye Island. A calibrated MODFLOW model is used for a prediction of groundwater level changes caused by the Recharge Dam MAR. Results of the simulations showed that the increased groundwater level caused by the realization and operation of three proposed weirs affects the volume of water infiltrated to the aquifer but does not cause the flooding of the adjacent area.

Earthquake-induced hydrologic changes in the geoengineered schist landslides of Cromwell Gorge, Central Otago

<p>Geoengineered groundwater systems located within seven large (> 100 ha surface area), deep-seated, slow-creep schist landslides in Cromwell Gorge (Otago, New Zealand) are observed to respond systematically to 10 large (>Mw6.2), regional earthquakes at epicentral distances of 130-630 km. The permeabilities of the schist landslides have previously been reported to be c. 1 x 10⁻¹⁷ - 4 x 10⁻⁶ m2 and the permeability structure is dominated by large fracture zones. Of the 315 hydrological instruments in the gorge for which data have been analysed, 21 monitoring well piezometers record repeated metre- or centimetre-scale groundwater level changes, and 12 underground V-notch weirs record elevated flow rates induced by the same earthquakes. Groundwater level changes exhibit consistent temporal characteristics at all monitoring sites, namely a time to peak pressure change on the order of one month and a subsequent recovery period on the order of one year. Changes in weir flow rate are near-instantaneous with maximum flow rates reached within 0-6 hours, followed by recession periods on the order of one month. Hydrological responses to different earthquakes at each monitoring site are systematic in terms of polarity and amplitude. This comprehensive dataset enables consistent patterns in the amplitude, time to peak pressure change and recovery time of groundwater level changes, and elevated weir discharge volumes in response to earthquake shaking to be documented. Earthquakes inducing hydrological responses have been categorised into five categories based on shaking characteristics (duration, bandwidth and amplitude). Larger hydrological responses and proportionally shorter time to peak pressure change and recovery time are associated with long duration (25-50 s or longer), high-amplitude, broad bandwidth shaking. The larger amplitudes of hydrological response and proportionally shorter times to peak pressure change and recovery times, are interpreted to represent greater temporary enhancement of the landslides hydraulic properties, particularly permeability. Understanding how earthquakes can enhance or otherwise affect hydraulic properties such as permeability in fractured reservoirs is intrinsically important and may prove of economic utility for both the geothermal and hydrocarbon energy sectors.</p>

Earthquake-induced hydrologic changes in the geoengineered schist landslides of Cromwell Gorge, Central Otago

<p>Geoengineered groundwater systems located within seven large (> 100 ha surface area), deep-seated, slow-creep schist landslides in Cromwell Gorge (Otago, New Zealand) are observed to respond systematically to 10 large (>Mw6.2), regional earthquakes at epicentral distances of 130-630 km. The permeabilities of the schist landslides have previously been reported to be c. 1 x 10⁻¹⁷ - 4 x 10⁻⁶ m2 and the permeability structure is dominated by large fracture zones. Of the 315 hydrological instruments in the gorge for which data have been analysed, 21 monitoring well piezometers record repeated metre- or centimetre-scale groundwater level changes, and 12 underground V-notch weirs record elevated flow rates induced by the same earthquakes. Groundwater level changes exhibit consistent temporal characteristics at all monitoring sites, namely a time to peak pressure change on the order of one month and a subsequent recovery period on the order of one year. Changes in weir flow rate are near-instantaneous with maximum flow rates reached within 0-6 hours, followed by recession periods on the order of one month. Hydrological responses to different earthquakes at each monitoring site are systematic in terms of polarity and amplitude. This comprehensive dataset enables consistent patterns in the amplitude, time to peak pressure change and recovery time of groundwater level changes, and elevated weir discharge volumes in response to earthquake shaking to be documented. Earthquakes inducing hydrological responses have been categorised into five categories based on shaking characteristics (duration, bandwidth and amplitude). Larger hydrological responses and proportionally shorter time to peak pressure change and recovery time are associated with long duration (25-50 s or longer), high-amplitude, broad bandwidth shaking. The larger amplitudes of hydrological response and proportionally shorter times to peak pressure change and recovery times, are interpreted to represent greater temporary enhancement of the landslides hydraulic properties, particularly permeability. Understanding how earthquakes can enhance or otherwise affect hydraulic properties such as permeability in fractured reservoirs is intrinsically important and may prove of economic utility for both the geothermal and hydrocarbon energy sectors.</p>

Groundwater Hydrograph Decomposition With the HydroSight Model

Groundwater, the most important water resource and the largest distributed store of fresh water in the world, supports sustainability of groundwater-dependent ecosystems and resilient and sustainable economy of the future. However, groundwater level decline in many parts of world has occurred as a result of a combination of climate change, land cover change and groundwater abstraction from aquifers. This study investigates the determination of the contributions of these factors to the groundwater level changes with the HydroSight model. The unconfined superficial aquifer in the Gnangara region in Western Australia was used as a case study. It was found that rainfall dominates long-term (1992–2014) groundwater level changes and the contribution rate of rainfall reduced because the rainfall decreased over time. The mean rainfall contribution rate is 77% for climate and land cover analysis and 90% for climate and pumping analysis. Secondly, the increasing groundwater pumping activities had a significant influence on groundwater level and its mean contribution rate on groundwater level decline is -23%. The land cover changes had limited influence on long-term groundwater level changes and the contribution rate is stable over time with a mean of 2%. Results also showed spatial heterogeneity: the groundwater level changes were mainly influenced by rainfall and groundwater pumping in the southern study region, and the groundwater level changes were influenced by the combination of rainfall, land cover and groundwater pumping in the northern study region. This research will assist in developing a quantitative understanding of the influences of different factors on groundwater level changes in any aquifer in the world.

Estimating surface displacement in the Hanshin area, Japan, by PS-InSAR analysis using satellite Sentinel-1 data

&lt;p&gt;The 2018 northern Osaka earthquake with a magnitude 6.1 earthquake struck on June 18, 2018 in northern Osaka, causing enormous damage. SAR interferometry using satellite synthetic aperture radar (SAR) data can detect surface displacement distribution over a wide area and is effective for observing surface displacement during an earthquake. On the other hand, it is also important to observe the tendency of long-term surface displacement around active faults on a yearly basis in order to monitor the deformation at and around active faults. In this study, we used persistent scatter SAR interferometry (PS-InSAR) to clarify the recent surface displacement including before and after the 2018 northern Osaka earthquake near the Arima-Takatsuki Fault Zone and the Mt. Rokko active segment, near the epicenter of the earthquake. PS-InSAR analysis is a method that analyzes coherent pixels only, and can extract surface displacements with less noise than the conventional two-pass SAR interferometry. By using Sentinel-1 data, we expect to understand a long-term surface displacement and temporal changes in displacement pattern by comparing with the results using other satellites in previous studies. As a result of our analysis, we found that (i) ground subsidence occurred near the Mt. Rokko active segment, (ii) subsidence or eastward displacement occurred in the eastern part of the Takarazuka GNSS station, (iii) surface displacement in the wedge-shaped area located between the Arima-Takatsuki Fault Zone and the Mt. Rokko active segment is suggested to be caused by groundwater level changes, (iv) groundwater level changes may have caused surface displacement considered to be uplift in the wide area between the Ikoma Fault Zone and Uemachi Fault Zone, and (v) slip of the source fault may have caused surface displacement around the epicenter of the 2018 northern Osaka earthquake. Furthermore, we validated the estimated surface displacements by comparison with GNSS measurements and previous studies. These results suggest that surface displacement near the Arima-Takatsuki fault zone was caused by the 2018 northern Osaka earthquake. In order to reveal the mechanism of surface displacement in the vicinity of the fault, it is necessary to continue to monitor the surface displacement in this area using time-series SAR interferometry.&lt;/p&gt;&lt;p&gt;&amp;#160;&lt;/p&gt;&lt;p&gt;&amp;#160;&lt;/p&gt;&lt;p&gt;We acknowledge Sentinel-1 data provided from the European Space Agency (ESA) based on the open data policy.&lt;/p&gt;

Sentinel-2 water indexes application for the underground water level analyses in Ovidiopol area of Odessa region (Ukraine).

&lt;p&gt;&lt;strong&gt;Problems statement and purpose&lt;/strong&gt;. Studied area has a high level of agricultural development. There are different irrigation and drainage systems located there. Significant part of the supplied water losses from the irrigation network because of filtration and reaches the groundwater level, which begins to rise. Raising of groundwater level can lead to waterlogging of the soil, secondary salinization and, as a consequence, to a decrease in crop yields. As result, the groundwater level is under intense technogenic impact. Control and analyses of groundwater level changes with remote sensing methods for Ovidiopol area is the main goal of that work. The object of study is the groundwater level regime in the territory of Lower Dniester irrigation system in Ovidiopol district, Odessa region. The subject of research is water indexes application for analyses of groundwater level changes.&lt;/p&gt;&lt;p&gt;&lt;strong&gt;Data and methods.&lt;/strong&gt;&lt;strong&gt; &lt;/strong&gt;The local system of groundwater observation includes 7 drillholes in Nadlimanskoe village and around. These drillholes located in different geomorphological, hydrogeological and technogenic conditions. The groundwater level was surveyed monthly in 2017. &amp;#160;Sentinel-2 2A images for each month from March 2017 to December 2017 were used for studied area. All satellite images has atmospheric correction. Three water indexes NDWI, MNDWI, NDPI were calculated for drillhole points for each month in 2017 year.&lt;/p&gt;&lt;p&gt;&lt;strong&gt;Results.&lt;/strong&gt; Significant coefficients of correlation were obtained in comparison between groundwater level changes and water indexes in some drillholes points. The highest numbers of correlation connected with free of construction areas and for drillholes, which are located outside of villages. Water indexes have the same intra-annual dynamics of changing as groundwater level. NDWI is the most informative and representative index for studied area. Other types of indexes should be used for build-up areas analyses. However, existed water indexes can be used for groundwater level analyses in the open fields and in river slopes and valleys with developed irrigation system.&lt;/p&gt;

Seismological and Hydrogeological Controls on New Zealand-Wide Groundwater Level Changes Induced by the 2016 Mw 7.8 Kaikōura Earthquake

© 2019 K. C. Weaver et al. The 2016 Mw 7.8 Kaikōura earthquake induced groundwater level changes throughout New Zealand. Water level changes were recorded at 433 sites in compositionally diverse, young, shallow aquifers, at distances of between 4 and 850 km from the earthquake epicentre. Water level changes are inconsistent with static stress changes but do correlate with peak ground acceleration (PGA). At PGAs exceeding 2 m/s2, water level changes were predominantly persistent increases. At lower PGAs, there were approximately equal numbers of persistent water level increases and decreases. Shear-induced consolidation is interpreted to be the predominant mechanism causing groundwater changes at accelerations exceeding 2 m/s2, whereas permeability enhancement is interpreted to predominate at lower levels of ground acceleration. Water level changes occur more frequently north of the epicentre, as a result of the fault's northward rupture and resulting directivity effects. Local hydrogeological conditions also contributed to the observed responses, with larger water level changes occurring in deeper wells and in well-consolidated rocks at equivalent PGA levels.