Urgent Measure of Geospatial Parameters for Flood Modeling in Indonesia

Indonesia is prone to flood. Many areas including cities have a suffering flood in history until these recent days.  Jakarta city, for example, had suffering flood since Dutch colonial time a few hundred years ago and even earlier until this recent year 2018. Besides Jakarta, Indonesia has other big cities like Bandung, Semarang, Surabaya and Medan which frequently suffered from the flood. Growing cities like Langsa, Pekanbaru, Palembang, Pamanukan, Garut, Cirebon, Pekalongan, Demak, Bojonegoro, Banjarmasin, Gorontalo, Bima are also suffering flood in almost regularly. The flood condition is different from time to time due to rain intensity and rivers capacity are leading to disaster.  Low land areas such as coastal areas and peatland areas in many regions of Indonesia are experiencing the same disaster. Adaptation and mitigation should be taken against this flood disaster. In order to find the best adaptation and mitigation, first, we must understand the characteristic of the flood by creating flood models. Essential parameters of flood modeling would include geospatial parameters (e.g., Digital Elevation Model, Land use, and rivers geometry).  Unfortunately for Indonesia's case, these geospatial parameters of the flood are still relatively weak.  We can see that several flood models of Indonesia are in low accuracy spatially and temporarily. So, the measure of geospatial parameters is urgent. This paper will highlight this urgency

Adaptation of ‘Early Climate Change Disaster’ to the Northern Coast of Java Island Indonesia

In the last few decades, the tidal inundation and abrasion along northern coast of Java Indonesia have been grown very rapidly. These situations are far beyond the geological scale. These are way too fast. Time series of high resolution satellite image data shows very clearly the tidal inundation and abrasion existence. In the recent years in fact the tidal inundation is obviously going further deeper inland. Many of urban and other areas like farming area, fishpond, etc. have been suffered tidal inundation and becoming worse in times. First it was only few centimetres of inundation and come only at a high tide, but now it can be more than a half of meter and coming at regular tide, and even has comes permanently in certain places. Many of the area along northern coast of Java are also suffering abrasion due to frequently of bad weather with storm surge strike the coastal area. What is happening to the northern coast of Java Island Indonesia is one most clear pictures of ‘early climate change disaster’. Adaptation has been created against this ‘early climate change disaster’ such as build dykes, elevate the land, houses, infrastructures, etc. This paper will tell in details and comprehensively regarding adaptation of ‘early climate change disaster’ to the northern coast of Java Island Indonesia. This is one way to remain on what would happen in the future world wide as the global climate change consequences are finally coming. We have seen the news of the projection model of sinking of coastal cities in the world, vanishing Islands around the Pacific, etc. in the future

The Use of GNSS GPS Technology for Offshore Oil and Gas Platform Subsidence Monitoring

Due to oil and gas exploitation, offshore oil and gas platform may experience subsidence. Continuing subsidence may deform the platform infrastructures, adding the risk for any failure on the platform objects. The failure means disaster. Therefore the subsidence information is mandatory for risk assessment and safety requirement. Repeatedly or continuous monitoring of accurate positions on the platform by using global navigation satellite system global positioning system (GNSS GPS) technology may reveal the changing of even small positions which are representing subsidence on the platform. This chapter will be deeply discussed on the use of GNSS GPS technology for offshore oil and gas platform subsidence monitoring, especially in Indonesia, the archipelago country where long baseline between reference station in the land and monitoring station at the sea slightly exists. The capability and especially the high performance of this technology on deriving subsidence information along with data sample of long baseline will be highlighted

Insight into the Correlation between Land Subsidence and the Floods in Regions of Indonesia

Land subsidence by definition is the lowering of ground level from certain elevation references. The rates of subsidence can commonly vary between 1 and 20 centimeters per year and even more in certain places. Subsidence produces impacts such as infrastructure damage, problems with drainage, wider expansion of flood water, as well as tidal inundation (flooding by sea water at coastal areas experiencing land subsidence). These impacts are quite costly. All this is disastrous. In a number of regions of Indonesia, land subsidence and negative impacts in the shape of flooding and tidal inundation clearly exist. In Jakarta and Bandung we can see that the subsiding areas close to rivers frequently suffer from flooding. Tidal inundation is a regular feature at subsiding coastal areas such as Jakarta, Blanakan, Semarang, and Demak. Since these negative impacts are clearly formed a disaster while mitigation and or adaptation is still a big homework, in this case for better adaptation and mitigation in the future, understanding deeply the correlation of land subsidence and flooding is necessary as discused in this chapter. We conclude that the correlation is quite tremendous and indeed producing a disaster

Study the capabilities of RTK Multi GNSS under forest canopy in regions of Indonesia

For more than two decade, the position on the earth can be precisely determined “real-time” in the order of few centimeters by Real Time Kinematic (RTK) GNSS (Global Navigation Satellite Systems) Method. Nevertheless, few limitations are still recognized such as degradation of accuracy against limited satellite visibilities (e.g. heavy satellite obstructions from forest canopy). It usually takes time to resolve the ambiguities or even in many occasion resulted in failure. Fortunately since recent years to the future seems more satellite systems beside GPS and GLONASS are being launched such as BEIDOU, GALILEO, QZSS, etc. It means that more satellite will be existed above the sky. The term GNSS has changed into Multi GNSS. This Multi GNSS is theoretically adding the value to previous GNSS System like GPS; problems of limited satellite visibilities (e.g. under forest canopy) to the position accuracy perhaps will reduce. Within this paper we try to do study the capabilities of RTK Multi GNSS under forest canopy in Indonesia. We observed by RTK in the forest areas which have canopy of 40 to 90 percent. As conclusion we found improvement in positioning result of even area of very limited satellite visibilities

The investigation on high-rise building tilting from the issue of land subsidence in Jakarta City

One of the issues from land subsidence consequences is tilting on building. At the places where differential subsidence is existed we might literally see the building tilted. Jakarta is a mega city in Indonesia where significant land subsidence (e.g. 1-26 centimeter per year) is happening today. Issue of tilting on buildings due to land subsidence in Jakarta has been raisin. There is one high-rise building namely Menara Saidah which is judging to be tilting. As consequences the building has been abandoned. The building in the office of House of Representative is also being rumored to be tilting. Judging and rumored are not scientific, we need real measurements. There are more than two hundreds of high-rise buildings established in Jakarta city. We use the Terrestrial Laser Scanner survey to investigate the issue of high-rise building. This technology has capability to create 3D object with milimeter accuracy. Tilting on the building can be seen simply by their verticality. We have chosen several high-rise buildings to accurately measure, especially where large subsidence is there. This paper is a highlight on the investigation. As the conclusion we found the verticality of investigated buildings are still within the tolerance

Zenith Wet Delay (ZWD) Seasonal Correlation with Rainfall in Cikapundung River Discharge, North Bandung Region, Indonesia

In a GPS survey study, the biases produced by the ionosphere and troposphere layers are known as ionospheric biases and troposphere bias. The distance deviation due to the slowing travel time of GPS signals in troposphere is commonly referred to as Zenith Tropospheric Delay (ZTD). The magnitude of this ZTD can also be used to characterize and analyze the troposphere conditions around the GPS observation area. This can be done by separating the wet delay component from ZTD, so as to obtain Zenith Wet Delay (ZWD) and dry component so as to obtain Zenith Hydrostatic Delay (ZHD). The total moisture content in the troposphere (precipitable water vapor, PWV) of an area can be estimated based on the bias characteristics of zenith wet delay (ZWD). The ZWD pattern is very important in the study of atmospheric water cycles which are associated with rainfall patterns and flood events. The methods used in the research include preliminary data processing and estimation of ZTD value using RTKLIB 2.4.2. This article analyzes the correlation between ZWD, rainfall and Cikapundung river discharge in the North Bandung Region (KBU), based on the daily average data in the 2011-2015 observation period. Based on the reconstruction of harmonic components, it was found that the seasonal pattern of river discharge is correlating with the seasonal pattern of rainfall and moisture content in the troposphere. The pattern of the three variables is strongly influenced by the Asian and Australian Monsoon exchanges phenomena. Linear correlation between ZWD and river discharge exhibits clear results, which is based on the Pearson correlation value is 88.84% with a 95% confidence level using t-student statistic. Based on cross-spectrum analysis, the three variables are dominated by the seasonal cycle of one-year monsoon (annual) and the six-month cycle phenomenon (semi-annual)

The Potency of the Modernized GNSS Signals for Real-Time Kinematic Positioning

GNSS positioning has become popular in the past decade as an efficient method of precise and real-time positioning. It is relatively low cost and ease-of-use. Up to now, several parameters were defined to characterize the performance of real-time positioning: availability, precision, accuracy. This article evaluates the performance of signal linear combinations for real-time positioning, both for static as well as the kinematic positioning. This article starts with the investigation of linear combinations (LC) rising from the carrier frequencies of the GNSS systems. Some Linear Combination shows potential benefits in carrier phase integer ambiguity resolution, particularly utilizing the Galileo and Beidou signal phase carrier. For each system, a set of combinations was studied, analyzed, and then selected during the development of GNSS positioning method utilizing the Least-squares Ambiguity Decorrelation Adjustment (LAMBDA). Special signal selection can affect the estimated position and its standard deviation. To further analyze, the results obtained from data processing are compared with respect to baselines and signals. The ambiguity fixing rate is correlated with the baseline length and the method as well as the signals that were used. The analysis of the measurement noise level was first conducted to set a baseline for the real-time GNSS positioning application. According to the results and to assess the data quality and positioning performance of GNSS in respect with GPS (Global Positioning System), an experimental test has established using MGEX data. This research investigates the satellite visibilities, multipath, Signal to Noise Ratio (SNR), and positioning performance. It is shown that in every epoch, at least 8 satellites are visible. The SNR’s are up to 60 dBHz, the code multipath residuals varies within ~1 m, while the phase residuals varies by about ~2 cm. hence the modernized GNSS signals have potencies to improves the RTK positioning

The Effect of TLS Radome on GNSS Precise Positioning

This article presents the results of a test carried out to check the usability of spherical TLS targets as GNSS antenna radomes (herein called TLS radomes). On different days, the survey was conducted using two GNSS antennas, one of them with a TLS radome. Measurements were made using 2 roof pillars on the rooftop as base-rover pillars with little obstruction. The measurements were carried out for approximately 1 hour in every scenario. The software used for data processing is MATLAB-based software and the raw data were processed using the double difference (DD) strategy to obtain optimal results. The results of the data processing indicated that the TLS radome has no significant influence on availability and accuracy of estimated position. The signals are slightly attenuated by the radome (1-2 dBHz) and the noise level is slightly increased but both effects are negligible for practical purposes. However, we found that the antenna should be calibrated with the TLS radome to clarify apparent minor phase center eccentricities (1-2 mm) and to reduce systematic effects with long periods (few minutes) and amplitudes up to about 5 mm which are likely due to phase center variations

Walanae Fault Kinematic Deduced from Geometric Geodetic GNSS GPS Monitoring

The western Sulawesi region has the main structural boundary, the Palu Koro Fault which divides from Palu Bay at the northest part to Central Sulawesi and continues into the Bone Gulf in southest part. In the southern part of this region, namely the South Sulawesi Arm zone, there is a Walanae fault which is defined as a sinistral wrench with a NW-SE direction that divides the South Arm of Sulawesi. This fault in the northern part is expected to continue to the northwest intersecting the Makassar Strait and unite with Paternoster-Lupar (Kalimantan) sutures and at the southest ending in Flores thrust fault. Walanae fault system did not only have one strand but was divided into 4 parts, namely the northern East Walanae Fault with a slip rate of 6.634 mm/year and the southern part with a 7.097 mm/year of slip rate, as well as the northern part of West Walanae Fault with a slip rate of 4.528 mm/year and the southern part with a slip rate of 3.270 mm/year. The northern part of Walanae fault system has opening or spreading pattern occurs that is in harmony with the formation of Walanae depression. By using simple geometric modeling, we found the fault system have 2 strain partitions with dominant sinistral strike slip pattern at southern part and combination between left lateral strike slip with thrust fault pattern at northern part