Induced Bank Filtration: Hydraulic Testing of Pilot Filters

Hydraulic tests were performed on two pilot scale filters as part of a water treatment project in the village of Nersa, Karnataka, India. The filters use locally sourced alluvial material to filter E.coli contamination using natural processes that mimic those in Riverbank Filtration (RBF). Two pilot scale filters were tested, one containing locally sourced granular activated carbon (GAC) and one without. A falling head test and tracer test were preformed, and breakthrough curves were used to analyze the hydraulic performance. E.coli data were also collected, and percent removal was calculated to determine the effectiveness of the filters. Relative to the influent water, the E.coli removal percentage of Filter 1 (no GAC) was consistently high and ranged between 97.1% and 100% E.coli. The addition of GAC did not improve performance in this study. Overall, the effectiveness in bacteria removal observed in the non GAC filter warranted construction of a full-scale system.

Tectonic, hydrogeologic, and climatic controls on Late Holocene dune formation, China Lake basin, Indian Wells Valley, California, USA

Analysis of patterns of faulting and hydrogeology, stratigraphic and sedimentologic studies, and luminescence dating of aeolian deposits in China Lake basin provide new perspectives on the origins and development of Late Holocene dunes and sand ramps in the seismically active Indian Wells Valley of eastern California. Aeolian dune and sand sheet deposits were sourced from alluvial material derived from granitic rocks of the south-eastern Sierra Nevada and are concentrated in areas with sand-stabilizing phreatophyte vegetation influenced by high groundwater levels along the active oblique-normal Little Lake and Paxton Ranch faults, which locally form barriers to groundwater flow. Three episodes of sand accumulation are recognized (2.1 ± 0.1 to 2.0 ± 0.1 ka, 1.8 ± 0.2 to 1.6 ± 0.2 ka, and 1.2 ± 0.1 to 0.9 ± 0.1 ka) during conditions in which sediment supplied to the basin during periods of enhanced rainfall and runoff was subsequently reworked by wind into dunes and sand ramps at the transition to more arid periods. Understanding the role tectonics plays in influencing the hydrogeology of seismically active lake basins provides insights to accurately interpret landscape evolution and any inferences made on past hydroclimate variability in a region.

Aeolian sediments in paleowetland deposits of the Las Vegas Formation

The Las Vegas Formation (LVF) is a well-characterized sequence of groundwater discharge (GWD) deposits exposed in and around the Las Vegas Valley in southern Nevada. Nearly monolithologic bedrock surrounds the valley, which provides an excellent opportunity to test the hypothesis that GWD deposits include an aeolian component. Mineralogical data indicate that the LVF sediments are dominated by carbonate minerals, similar to the local bedrock, but silicate minerals are also present. The median particle size is ~35 μm, consistent with modern dust in the region, and magnetic properties contrast strongly with local bedrock, implying an extralocal origin. By combining geochemical data from the LVF sediments and modern dust, we found that an average of ~25% of the LVF deposits were introduced by aeolian processes. The remainder consists primarily of authigenic groundwater carbonate as well as minor amounts of alluvial material and soil carbonate. Our data also show that the aeolian sediments accumulated in spring ecosystems in the Las Vegas Valley in a manner that was independent of both time and the specific hydrologic environment. These results have broad implications for investigations of GWD deposits located elsewhere in the southwestern U.S. and worldwide.

Mineralization Study of Volcanic Rocks in Colo Volcano Tojo Una-Una Central Celebes

Colo Volcano is an active volcano located on Una-Una Island, Tojo Una-Una Regency, Central Sulawesi Province. Volcanism and magmatism of Mount Colo are still in progress, and this has certainly triggered mineralization in volcanic rocks which is interesting for study. This research aims to reveal the mineralization characteristics of volcanic rocks in the study area. This research was conducted through investigative methods in the form of field observations and laboratory through petrographic and rock chemistry (X-Ray Defraction analysis) to reveal the presence of alteration minerals as a characteristic of mineralization. The results of this study indicate that the volcanic rocks present are tuff and volcanic breccia in the form of pyroclastic deposits associated with alluvial material and andesite rocks. Identification of alteration minerals through XRD test shows the presence of hydrothermal alteration minerals with a formed temperature of 300 ° C such as Quartz, Calcite, Clinochlore, Albite, Dickite, Andesine, and K-Feldspar which are classified into Argillic and Propylitic alteration types.

Geomorphology of the small island of Tidore and Hiri (North Maluku, Indonesia)

Tidore and Hiri Islands in North Maluku Province is the result of a complex tectonic setting. In contrast with Ternate Island and its well-known volcano, Gamalama volcano, there is still a lack of research about volcanic information or volcanic landform in Tidore and Hiri Islands. Even though the two islands also have volcanoes, i.e., Hiri and Tidore/Kiematubu volcano. This study aims to provide geomorphological information, especially in Tidore and Hiri Islands, since this information is hard to find whereas it is very important to disaster mitigation and landuse planning. We used remote sensing images, digital elevation models (DEM), and geological maps to classify geomorphological information of the small island of Tidore and Hiri in the North Maluku based on geomorphological aspects, i.e., morphology, morphogenesis, morpho-chronology, and morpho-arrangement. As a volcanic island, the slope in Tidore and Hiri Island is dominated by a slightly steep (8°-16°) and a steep slope (16°-35°), while the relief is dominated by hills and mountainous. Volcanic landforms on Tidore and Hiri Islands are characterized by relatively symmetrical cone-shaped volcanic cones, which are accumulations of falling pyroclastic material and lava ejected from magma vents. Volcanic islands include the case of Tidore and Hiri Island have radial centrifugal river flow patterns. The material on Tidore and Hiri Islands is dominated by Holocene volcanic rocks. In Tidore, there is alluvial material on the west and east coasts of the island. This study result also can be developed into more detailed geomorphological maps, or landscape evolution in a volcanic island, or spatial planning.

Analysis and Zonation of Land Vulnerability Areas in Pekon Karangrejo Ulubelu Tanggamus Using Microzonation Method

Ulubelu Tanggamus is an area that have geothermal energy potential. This region consists of a geological structure in the form of graben and reverse fault formed between Mount Rendingan and Mount Kukusan. Identifications that can be done include surveys to map soil characteristics in shaking responses using microzonation methods. This study aims to analyze the values ​​of dominant frequency, dominant period, Vs30 and amplification. The stages of the research carried out are processing data to obtain dominant frequency, calculating the value of the dominant period, calculating the value of Vs30 and the amplification value, and making a map of the soil vulnerability of the UlubeluTanggamus area. Based on the distribution of the dominant frequency values, the UlubeluTanggamus geothermal area is dominated by a dominant Frequency (F0) >0.5Hz which is expected to be a very thick surface thickness of sediments more than 30m. The distribution of the dominant period value obtained is (T0)>1 where the character of the sedimentary rock type is very soft consisting of alluvial material formed from sedimentation of deltas, top soil, and mud. The distribution of the Vs30 value is dominated by the value of 100 <Vs30<200 and obtains an amplification value of 2<A0<6 times where the area is an area with a moderate risk category to the danger of soil vulnerability.

Researches Concerning the Configuration of Geotextiles in the Execution of Regulatory Works in the Riverbeds

The paper deals with the behaviour at hydrodynamic action of the geotextiles used in carrying out the regularization and shore defence works located in riverbed. The geotextiles have lately presented applications for the execution of bottom thresholds, of the management dams in riverbed. Also, geotextiles have become an important component in the structure of river defence works on riverbeds. The research was carried out on the lower course of the Moldova River in the area of Pildesti, Neamţ County. The dynamic action of the floods, through the liquid and solid flows, influences the stability and the resistance over time of the constructions made from geotextiles. The researchers analysed the behaviour of the geo-bags made of polyester bags filled with local materials (sand and gravel stabilized with cement), used in the structure of the bottom thresholds, steering dams and in the shore defence works. The research results indicate a differentiated behaviour of the geo-bags depending on the location (in the water, or on the shore) and the mode of action of the water (dynamic or static). The action of the water, through the liquid and solid flow, degraded the structure of the geo-bags by breaking and emptying the filling material. The geo-bags showed a reduced resistance to the action of the alluvial material, especially when the dosage of cement indicated by the design was not achieved. The research highlighted the good behaviour of the geo-bags in the erosion phenomenon of the riverbed, when they were mulched on the erosion zones and ensured the continuity of the constructions in the riverbed (bottom thresholds and shore defences).

RESEARCHES ON BEHAVIOUR OF REGULATION WORKS LOCATED IN MORPHOLOGICALLY UNSTABLE RIVER BEDS

The paper deals with the behaviour of geotextile regulation works on the dynamic action of floods in erodable river beds. Geotextiles have become an important component in the structure of river bed regulation and shore protection works. The dynamic action of floods, through liquid and solid flows, influences the stability and the resistance in time of geotextile constructions. The studies and researches were carried out on a sector of Moldova River between Soci and Pildeşti localities, on the territory of Iaşi and Neamţ counties. The researchers analysed the behaviour of geo-bagss made of polyester bags filled with local materials (generally sand and gravel) used for bottom sills, routing dikes and shore protection elements. The research results indicate a differentiated behaviour of geo-bagss according to their location (in water or on shore) and water action (dynamic or static). Water dynamic action has caused significant degradation of geo-bagss from bottom sills and routing dikes structures located in the river bed. Geo-bagss have low resistance to the alluvial material action (stone, trees) transported in the river bed during floods. The research highlighted the proper behaviour of geo-bagss during the river bed erosion phenomenon, when they moved and ensured the continuity of the bottom sills and their performance.

Evidence for Holocene sea level and climate change from Almenara marsh (western Mediterranean)

In the Almenara marsh (western Mediterranean), four cores were analyzed to establish the relationship between the marsh record of the Almenara marshlands and the environmental factors responsible for its evolution during the Holocene. One hundred and eighty-six samples were collected for sedimentologic and paleontological study: 63 for biomarker analysis; 5 for amino acid racemization (AAR) dating; and 5 for 14C dating. Litho and biofacies analyses identified distinct paleoenvironments, with the presence of a marsh environment alternating with inputs of alluvial material and marine sediments. Biomarkers indicated the constant presence of terrestrial (herbaceous) plants, together with a variable development of aquatic macrophytes. During the Holocene transgression, the Almenara marsh was occupied by oligohaline marsh facies with an oscillating water level and peat formation, which was established at the bottom of the record at 7570 cal yr BP and persisted until 3100±780 yr (AAR). Maximum surface flooding occurred at 5480 cal yr BP, registered 450m from the current coastline. At least three peat beds (dated with 14C dating and AAR) correlated with Bond (episode 5900 cal yr BP) and Wanner (episodes 4800–4500 and 3300–3500 cal yr BP) cycles and thus correspond to a regional model that affected the Northern Hemisphere.

Subsidence characterization and modeling for engineered facilities in Arizona, USA

Several engineered facilities located on deep alluvial basins in southern Arizona, including flood retention structures (FRS) and a coal ash disposal facility, have been impacted by up to as much as 1.8 m of differential land subsidence and associated earth fissuring. Compressible basin alluvium depths are as deep as about 300 m, and historic groundwater level declines due to pumping range from 60 to more than 100 m at these facilities. Addressing earth fissure-inducing ground strain has required alluvium modulus characterization to support finite element modeling. The authors have developed Percolation Theory-based methodologies to use effective stress and generalized geo-material types to estimate alluvium modulus as a function of alluvium lithology, depth and groundwater level. Alluvial material modulus behavior may be characterized as high modulus gravel-dominated, low modulus sand-dominated, or very low modulus fines-dominated (silts and clays) alluvium. Applied at specific aquifer stress points, such as significant pumping wells, this parameter characterization and quantification facilitates subsidence magnitude modeling at its' sources. Modeled subsidence is then propagated over time across the basin from the source(s) using a time delay exponential decay function similar to the soil mechanics consolidation coefficient, only applied laterally. This approach has expanded subsidence modeling capabilities on scales of engineered facilities of less than 2 to more than 15 km.