Dasapta Erwin Irawan

Groundwater and river water interaction on Cikapundung River: Revisited

The interaction between groundwater and Cikapundung river water has not changed significantly in 16 years of period. This paper revisit the similar research based on 43 measurement points: 13 dug wells, 2 springs, and 24 river, distributed along the riverbank at Curug Dago to Batununggal segment. The field measurements were taken in rainy season of April to May 2014 using portable instruments. Six parameters were measured: water level, temperature, total dissolved solids (TDS), dissolved-oxygen (DO), and pH. The new model is unable to detect significant change in water flow, however it finds two local anomalies in Dago Pojok and Cikapayang area. Both locations show local drawdown circle which can induce influent stream in overal effluent environment. Moreover, water quality parameters indicate mixing processes between groundwater and river water, with erratic pattern both in effluent and influent stream. Also some DO and TDS readings exceed the permissible limit. These values suggest a lifted groundwater ...

Groundwater and river water interaction at Ciromban and Cibeureum riverbank, Tasikmalaya: Can we solve water shortage?

Water shortage is a common problem in the high density settlement along the riverbank of Ciromban and Cibeureum River, Tasikmalaya, as the quality of the water also decreases. One of the solution is to maximize the use of river water. This study aims to investigate the interaction between river and groundwater along the riverbank as a function of land use impact. A river water and unconfined groundwater level mapping has been conducted to make water flow map, assuming both waters are in the same flow system. Physical parameters, temperature, TDS, and pH were measured at each stations to understand water characteristics. Based on observations at 50 dug wells and 12 river stations on July-August 2014, a close interaction between both water bodies has been identified with two flow systems: effluent flow (or gaining stream) at Cibereum river segment and influent flow (losing stream) at Ciromban river segment. Physical parameters show a high correlation in temperature, pH, and TDS. Hence, further evaluation should be taken before using river water as raw water supply in Tasikmalaya area.

Multivariate Analysis of Limestone Petrography Data on Kalipucang Formation Using R

Limestone may look physically and visually have the same characteristics but basically can be distinguished one of them with thin section rock analysis, this research to support petrography analysis of thin section rock data with a more quantitative approach using the method Principal component analysis and cluster analysis statistics to parse physical and visual characteristics. The study used 57 samples of thin section rock from three locations in a single rock formation, i.e. the location of Pancatengah-Tasikmalaya (PCT); Cijulang-Ciamis (CJL) and Sindangsari-Ciamis (SDS), analysed using open source software with replication R programming languages using packages: ggplot2; Dplyr; FactomineR; FactoExtra; Cluster and Ggcorrplot. The results of the study showed consistently the existence of three significant rock sampling classifications, i.e. one group showing the samples were in the area near the deposition with the main composition of foraminifera, algae, mud carbonate, coral fragments, Group 2 showed mixing with igneous rock with plagioclase composition, opaque, Glass, pyroxene and, Group 3 shows the rocks have been transported so that they are mixed with other sedimentary rocks having quartz compositions, iron oxides, rock fragments.

Static Electrode DC Resistivity Measurement at Surface Water for Pond Subsurface Layer Imaging

Resistivity methods in marine applications show slightly different processing techniques from land based resistivity surveys. Special DC resistivity instruments need to overcome difficulties in arranging the electrode with straight array lines and position. Some geoelectrical instrument manufacturers developed equipment which is able to measure resistivity values and positions in real time. In this paper we demonstrate an application of ordinary geoelectrical instruments for resistivity acquisition in water environment. This study is motivated by the inability to apply conventional DC resistivity instruments in water environment. Land resistivity survey array is arranged on the surface of water using static electrode mode. The method has been tested in various environments, such as ponds/lakes with quiet until rough waves and also measurements at coastal environments. Measurement at the ponds/lakes water environment resulted in data that are almost identic to the measurements obtained using standard land DC resistivity method. On the other hand the measurement in coastal environment does not work properly, possibly due to the lack of power source.

Spatial analysis of groundwater quality data using geoR and mgcv R-package

Quantitative-spatial analysis has been applied to 295 samples of shallow groundwater quality data from Bandung-Soreang Groundwater Basin (BSGwB) taken in 1997, 1998, 2007, 2010, and 2011. This paper discuss the use of variogram using geoR and generalised additive model (GAM) using mgcv R-package to identify the spatial distribution and mixing process betwee groundwater and Cikapundung river water. The variograms show significant water quality trend in north-south direction, and in the direction to the Cikapundung River. From the GAM tests using gaussian and gamma family, some significant elements can be identified: (1) geological control from Fe, Mn, Na concentration; (2) agricultural control from NO2, NO3 concentration; and (3) other surficial control from EC, CO3, CO2, SO4 concentration. Both analysis suggest the close interaction between groundwater and river water and the occurrence of mixing between both.

Revisiting hydrostratigraphy in Bandung-Soreang groundwater basin: A well-logs re-analysis

An attempt to revisit the hydro-stratigraphy of Bandung-Soreang Groundwater Basin (BSGB) has been done based on 111 well-logging training dataset. Transformation of resistivity values from well-log data to relative porosity and permeability used Chillingarian approach and Baker-Hughes Atlas of log responses. Then boundary marker was drawn to separated different aquifer layers. Simple linear regression equations were derived from the transformation: (a) tuf layers: θ = −0.0023ρ + 2.5619, μ = −63.514θ + 167.38, σ = 22.912 μ + 238.78; (b) clay layers: θ = −0.0181 ρ + 2.6281, μ = −61.842 θ + 163.91, σ = 5.1202 μ − 11.503; (c) sand layers: θ = −0.0078 ρ + 2.5992, μ = −60.75 θ + 161.02, σ = 394.35 μ − 2156.8. Based on the new aquifer taxonomy, three hydro-stratigraphic units (HSU) and six sub HSU have been defined. UHs 1 is the top layer of the BSGB, located at elevation above 650 masl. It has three sub HSU that consists of tuf and sand. The permeability (K) values of this unit range from 0,0014 to 0.1 m per da...