Time filter

Source Type

Saputra M.A.,Center for Material and Technical Product | Meyilani R.,Research Center for Water Resources
Proceedings of the 2015 International Conference on Automation, Cognitive Science, Optics, Micro Electro-Mechanical System, and Information Technology, ICACOMIT 2015 | Year: 2015

Product certification is the process of certifying that a certain product has passed performance tests and quality assurance tests, and meets qualification criteria stipulated in contracts, regulations, or specifications (typically called «certification schemes»). Product certification is often required in sensitive industry and marketplace areas where a failure could have serious consequences, such as negatively affecting the health and welfare of the people or person using that product. Off-schedule and cost overrun became very important issues in the management of SNI product certification. As a public service, product certification needs to transform from traditional based service (manual process) to electronic based service (digital process) to ensure the effectiveness and efficiency. This research has been conducted by using Business Process Re-engineering (BPR) method to find critical improvement which is focused on process. This paper proposed an improvement design of product certification service in Indonesia. This improvement design has been measured by time analysis method to prove that the new design can achieve the best quality. © 2015 IEEE.

Sutanto S.J.,UNESCO IHE | Sutanto S.J.,Research Center for Water Resources | Sutanto S.J.,University Utrecht | Wenninger J.,UNESCO IHE | And 4 more authors.
Hydrology and Earth System Sciences | Year: 2012

Knowledge of the water fluxes within the soil-vegetation-atmosphere system is crucial to improve water use efficiency in irrigated land. Many studies have tried to quantify these fluxes, but they encountered difficulties in quantifying the relative contribution of evaporation and transpiration. In this study, we compared three different methods to estimate evaporation fluxes during simulated summer conditions in a grass-covered lysimeter in the laboratory. Only two of these methods can be used to partition total evaporation into transpiration, soil evaporation and interception. A water balance calculation (whereby rainfall, soil moisture and percolation were measured) was used for comparison as a benchmark. A HYDRUS-1D model and isotope measurements were used for the partitioning of total evaporation. The isotope mass balance method partitions total evaporation of 3.4 mm dĝ̂'1 into 0.4 mm dĝ̂'1 for soil evaporation, 0.3 mm dĝ̂'1 for interception and 2.6 mm dĝ̂'1 for transpiration, while the HYDRUS-1D partitions total evaporation of 3.7 mm dĝ̂'1 into 1 mm dĝ̂'1 for soil evaporation, 0.3 mm dĝ̂'1 for interception and 2.3 mm dĝ̂'1 for transpiration. From the comparison, we concluded that the isotope mass balance is better for low temporal resolution analysis than the HYDRUS-1D. On the other hand, HYDRUS-1D is better for high temporal resolution analysis than the isotope mass balance. © Author(s) 2012.

Apip,Kyoto University | Takara K.,Kyoto University | Yamashiki Y.,Kyoto University | Sassa K.,International Consortium on Landslides | And 2 more authors.
Landslides | Year: 2010

This paper describes the potential applicability of a hydrological-geotechnical modeling system using satellite-based rainfall estimates for a shallow landslide prediction system. The physically based distributed model has been developed by integrating a grid-based distributed kinematic wave rainfall-runoff model with an infinite slope stability approach. The model was forced by the satellite-based near real-time half-hourly CMORPH global rainfall product prepared by NOAA-CPC. The method combines the following two model outputs necessary for identifying where and when shallow landslides may potentially occur in the catchment: (1) the time-invariant spatial distribution of areas susceptible to slope instability map, for which the river catchment is divided into stability classes according to the critical relative soil saturation; this output is designed to portray the effect of quasi-static land surface variables and soil strength properties on slope instability and (2) a produced map linked with spatiotemporally varying hydrologic properties to provide a time-varying estimate of susceptibility to slope movement in response to rainfall. The proposed hydrological model predicts the dynamic of soil saturation in each grid element. The stored water in each grid element is then used for updating the relative soil saturation and analyzing the slope stability. A grid of slope is defined to be unstable when the relative soil saturation becomes higher than the critical level and is the basis for issuing a shallow landslide warning. The method was applied to past landslides in the upper Citarum River catchment (2,310 km2), Indonesia; the resulting time-invariant landslide susceptibility map shows good agreement with the spatial patterns of documented historical landslides (1985-2008). Application of the model to two recent shallow landslides shows that the model can successfully predict the effect of rainfall movement and intensity on the spatiotemporal dynamic of hydrological variables that trigger shallow landslides. Several hours before the landslides, the model predicted unstable conditions in some grids over and near the grids at which the actual shallow landslides occurred. Overall, the results demonstrate the potential applicability of the modeling system for shallow landslide disaster predictions and warnings. © 2010 Springer-Verlag.

Kobayashi R.,Japan Environmental Sanitation Center | Sumarriani Y.,Research Center for Water Resources | Yamashita N.,Japan Environmental Sanitation Center | Ohta T.,Japan Environmental Sanitation Center | And 4 more authors.
Limnology | Year: 2013

A long-term declining trend of pH values has been observed for several rivers in areas of central Japan that are geologically dominated by acidic rocks such as granite, rhyolite, or chert. We monitored the seasonal variation in water chemistry in one of these rivers: the Araya River in Niigata Prefecture. During the 4-year survey period, we observed temporary acidification during the rainy and snowmelt seasons when the river flow rate abruptly increased. In the rainy season, the decrease in pH may be attributable to the dilution of almost all ions and increased leaching of NO3 - from the catchment. In the snowmelt season, decreases in pH were found to be associated with peaks of SO4 2-, where the SO4 2- was possibly derived from that accumulated in the snowpack. The data pertaining to the river showed that it had a sensitive response to meteorological events and was likely to be acid sensitive. The estimated mass balance of the river showed that the SO4 2- output exceeded the corresponding input to the Araya River catchment. Mobilization of internal sulfur accumulated in forest ecosystems might have contributed to the observed long-term acidification of this acid-sensitive river. © 2012 The Japanese Society of Limnology.

Arif C.,Bogor Agricultural University | Arif C.,University of Tokyo | Setiawan B.I.,Bogor Agricultural University | Sofiyuddin H.A.,Research Center for Water Resources | And 3 more authors.
Rice Science | Year: 2012

The current study proposes a novel method using Excel Solver to estimate, from limited data, crop coefficient (Kc) in paddy fields under intermittent irrigation (II). The proposed method was examined in a field experiment conducted at Karang Sari Village, Bekasi, West Java, Indonesia during the first rice season of 2007/2008 (December 2007 to April 2008) in the rainy season. As the control, continuous flooding irrigation (CF) was applied to the conventional rice cultivation fields. Based on the observed water storage, Excel Solver was used to estimate crop evapotranspiration. Estimated crop evapotranspiration was used to compute Kc value, then the average Kc values at each growth stage were compared with that for the CF treatment. The estimation method was evaluated by comparing estimated crop evapotranspiration and the crop evapotranspiration derived by the well established FAO procedure. Excel Solver estimated crop evapotranspiration accurately with R2 values higher than 0.81. Accordingly, more than 81% of the FAO crop evapotranspiration was described by the proposed method. Thus, Kc value could be well determined from those estimated crop evapotranspiration. Under the II treatment, the average Kc values were 0.70, 1.06, 1.24 and 1.22 for the initial, crop development, reproductive and late stages, respectively. These values were lower than those under the CF treatment for initial and crop development stages because of a minimal soil evaporation and intense dryness during these stages. However, average Kc values under the II treatment were higher than those under the CF treatment at the reproductive and late stages, indicating that the II treatment promoted more plant activity particularly for dry biomass production as indicated by a greater number of tillers per hill. © 2012 China National Rice Research Institute.

Sutanto S.J.,University Utrecht | Sutanto S.J.,Research Center for Water Resources | Hoffmann G.,University Utrecht | Hoffmann G.,French Climate and Environment Sciences Laboratory | And 4 more authors.
Journal of Geophysical Research Atmospheres | Year: 2015

ENSO (El Niño-Southern Oscillation) has profound effects on the global water cycle, which can be examined at the process level by investigating the associated water isotopologues. Many isotope-based studies are aimed at understanding ENSO variability in the tropics, however, focusing principally on near-surface processes and isotopologue signals. The goal of the present study is to investigate the atmospheric processes governing the changes in the isotopic composition of water vapor both near the surface and at midtroposphere in the Pacific region during ENSO events, using a combination of remote sensing data and model simulations. For the lower atmosphere (i.e., 1000 hPa), our results show that rainout processes, less rain reevaporation of falling droplets, and increase of convective updrafts and diffusive exchange within the convective systems contribute to "the isotope amount effect" and isotopically deplete the water vapor during wet conditions, in agreement with previous studies. However, we find that the ENSO-associated isotopic signal in the midtroposphere (i.e., 500 hPa) diverges from the near-surface response. Analysis suggests that transport of enriched water vapor from lower atmospheric layers through convective updrafts controls the enrichment of midtropospheric water vapor over the Pacific Ocean. In the observations, a strong positive correlation between the increase of convective precipitation and the isotopic composition of water vapor clearly points to such a mechanism (R of 0.7-0.8 in the Central Pacific and 0.5-0.6 in the West Pacific). Model results confirm this mechanisms though producing slightly lower correlation values, with R values of 0.6 in the Central Pacific and 0.5 in the West Pacific. However, the distinction between convective and stratiform precipitation remains a result of model-dependent parameterization. Our analysis suggests that two issues should be investigated in more detail in further studies: (1) the equilibrium and disequilibrium between rain droplets and surrounding vapor for convective and stratiform precipitation and (2) different convection schemes in the different isotopic general circulation models (GCMs) describing the triggering of convection and uplift of lower layer air to higher layers. Ideally, such a comparison of different isotopic GCMs can provide us with an interesting benchmark test for the performance of the different convection schemes during ENSO and can help to disentangle the importance of the different processes contributing to the amount effect. © 2015. American Geophysical Union. All Rights Reserved.

Sutanto S.J.,University Utrecht | Sutanto S.J.,Research Center for Water Resources | Hoffmann G.,University Utrecht | Hoffmann G.,CEA Saclay Nuclear Research Center | And 7 more authors.
Atmospheric Measurement Techniques | Year: 2015

Over the last decade, global-scale data sets of atmospheric water vapor isotopologues (HDO) have become available from different remote sensing instruments. Due to the observational geometry and the spectral ranges that are used, few satellites sample water isotopologues in the lower troposphere, where the bulk of hydrological processes within the atmosphere take place. Here, we compare three satellite HDO data sets, two from the Tropospheric Emission Spectrometer (TES retrieval version 4 and 5) and one from SCIAMACHY (SCanning Imaging Absorption spectroMeter for Atmospheric CHartographY), with results from the atmospheric global circulation model ECHAM4 (European Centre HAMburg 4). We examine a list of known isotopologue effects to qualitatively benchmark the various observational data sets. TES version 5 (TESV5), TES version 4 (TESV4), SCIAMACHY, ECHAM, and ECHAM convolved with averaging kernels of TES version 5 (ECHAMAK5) successfully reproduced a number of established isotopologue effects such as the latitude effect, the amount effect, and the continental effect. The improvement of TESV5 over TESV4 is confirmed by the steeper latitudinal gradient at higher latitudes in agreement with SCIAMACHY. Also the representation of other features of the water isotopologue cycle, such as the seasonally varying signal in the tropics due to the movement of the Intertropical Convergence Zone (ITCZ), is improved in TESV5 and SCIAMACHY compared to TESV4. A known humidity bias due to the cross correlation of H2O and HDO measurements, which is of particular importance for instruments with low sensitivity close to the surface, was analyzed by applying either a humidity bias correction or a suitable a posteriori analysis. We suggest that the qualitative and quantitative tests carried out in this study could become benchmark tests for evaluation of future satellite isotopologue data sets. © Author(s) 2015.

Sutanto S.J.,University Utrecht | Sutanto S.J.,Research Center for Water Resources | Van Den Hurk B.,University Utrecht | Dirmeyer P.A.,George Mason University | And 8 more authors.
Hydrology and Earth System Sciences | Year: 2014

Current techniques to disentangle the evaporative fluxes from the continental surface into a contribution evaporated from soils and canopy, or transpired by plants, are under debate. Many isotope-based studies show that transpiration contributes generally more than 70% to the total evaporation, while other isotope-independent techniques lead to considerably smaller transpiration fractions. This paper provides a perspective on isotope-based versus non-isotope-based partitioning studies. Some partitioning results from isotope-based methods, hydrometric measurements, and modeling are presented for comparison. Moreover, the methodological aspects of the partitioning analysis are considered, including their limitations, and explanations of possible discrepancies between the methods are discussed. We suggest sources of systematic error that may lead to biases in the results, e.g., instruments inaccuracy, assumptions used in analyses, and calibration parameters. A number of comparison studies using isotope-based methods and hydrometric measurements in the same plants and climatic conditions are consistent within the errors; however, models tend to produce lower transpiration fractions. The relatively low transpiration fraction in current state-of-the-art land-surface models calls for a reassessment of the skill of the underlying model parameterizations. The scarcity of global evaporation data makes calibration and validation of global isotope-independent and isotope-based results difficult. However, isotope-enabled land-surface and global climate modeling studies allow for the evaluation of the parameterization of land-surface models by comparing the computed water isotopologue signals in the atmosphere with the available remote sensing and flux-based data sets. Future studies that allow for this evaluation could provide a better understanding of the hydrological cycle in vegetated regions. © Author(s) 2014. CC Attribution 3.0 License.

Putra S.S.,Research Center for Water Resources | Corzo Perez G.A.,UNESCO-IHE Institute for Water Education | Van Der Pijl S.,Deltares | Kernkamp H.,Deltares | And 2 more authors.
Proceedings - 2014 6th International Conference on Information Technology and Electrical Engineering: Leveraging Research and Technology Through University-Industry Collaboration, ICITEE 2014 | Year: 2015

The physical process modeling of an estuary is a complex mechanism that comes along with the existence of uncertainty. In contrast, due to significant variability of flows in space and time, an extensive modeling effort must be accommodated with the application of parallelization technology. Therefore, the implication of estuary model parallelization to the model result uncertainty must be examined. In this research, a three dimensional (3D) hydrodynamic model of Columbia Estuary, located in Oregon, United States, was configured in cloud computing environment. The case study was simulated using DFlow Flexible Mesh software from Deltares. The model behaviors were evaluated in terms of water level, velocity, and salinity with the reverence of field observation data. The estuary model was calibrated in respect to physical parameters before parallelization process. Through calibration procedure, it was revealed that the model were sensitive to bed roughness, eddy viscosity coefficient, and eddy diffusivity coefficient. It can be concluded that the model parallelization technique had induced minor uncertainty contribution to the specific estuary model results. The pattern of uncertainties are varies within the range of parallel processes scenarios, as a result of automatic domain decomposition practice that produces additional diffusivity term to model. Meanwhile, there is an optimum parallel process scenario with minimum computational time. Some bargaining alternatives between model uncertainty and computational time are presented for the application of estuary parallel modeling. © 2014 IEEE.

Loading Research Center for Water Resources collaborators
Loading Research Center for Water Resources collaborators