Land Subsidence in the Texas Coastal Bend: Locations, Rates, Triggers, and Consequences

Land subsidence and sea level rise are well-known, ongoing problems that are negatively impacting the entire Texas coast. Although ground-based monitoring techniques using long-term global navigation satellite systems (GNSS) records provide accurate subsidence rates, they are labor intensive, expensive, time-consuming, and spatially limited. In this study, interferometric synthetic aperture radar (InSAR) data and techniques were used to map the locations and quantify rates of land subsidence in the Texas Coastal Bend region during the period from October 2016 to July 2019. InSAR-derived land subsidence rates were then validated and calibrated against GNSS-derived rates. The factors controlling the observed land subsidence rates and locations were investigated. The consequences of spatial variability in land subsidence rates in Coastal Bend were also examined. The results indicated that: (1) land subsidence rates in the Texas Coastal Bend exhibited spatial variability, (2) InSAR-derived land subsidence rates were consistent with GNSS-derived deformation rates, (3) land subsidence in the Texas Coastal Bend could be attributed mainly to hydrocarbon and groundwater extraction as well as vertical movements along growth faults, and (4) land subsidence increased both flood frequency and severity in the Texas Coastal Bend. Our results provide valuable information regarding not only land deformation rates in the Texas Coastal Bend region, but also the effectiveness of interferometric techniques for other coastal rural areas around the globe.

Small batteryless wireless solar powered GPS receivers for subcentimeter land deformation monitoring

<p>We design, implement, and validate a unique permanently deployed land deformation monitoring system using small (brick sized), cheap (approximately $100 USD), batteryless, solar powered singleband GPS wireless sensor nodes. Both hardware and software were designed, implemented, and validated by us. Constraints by our hardware and application prompted us to design a unique distributed relative static positioning algorithm designed for intermittent poor quality phase observable measurements, for sites with high multipath and high node densities requiring good solution accuracies; the static solutions were calculated on a daily basis. Our algorithm used a quarter of the bandwidth that would typically be required for an RF link used for a comparable application. GPS on time was observed to vary greatly from as little as 0.5 hours a day in winter to over 8 hours a day and summer in one of our tests. Typical solution precision was 4 mm 2DRMS. Simulations predicted an undesirable slowly changing solution bias that would repeat every year.</p>

Small batteryless wireless solar powered GPS receivers for subcentimeter land deformation monitoring

<p>We design, implement, and validate a unique permanently deployed land deformation monitoring system using small (brick sized), cheap (approximately $100 USD), batteryless, solar powered singleband GPS wireless sensor nodes. Both hardware and software were designed, implemented, and validated by us. Constraints by our hardware and application prompted us to design a unique distributed relative static positioning algorithm designed for intermittent poor quality phase observable measurements, for sites with high multipath and high node densities requiring good solution accuracies; the static solutions were calculated on a daily basis. Our algorithm used a quarter of the bandwidth that would typically be required for an RF link used for a comparable application. GPS on time was observed to vary greatly from as little as 0.5 hours a day in winter to over 8 hours a day and summer in one of our tests. Typical solution precision was 4 mm 2DRMS. Simulations predicted an undesirable slowly changing solution bias that would repeat every year.</p>

LANDSLIDES MONITORING WITH TIME SERIES OF SENTINEL-1 IMAGERY IN YEN BAI PROVINCE-VIETNAM

This paper presents an application of PS-InSAR method for determining landslide displacement velocity in Van Yen district, Yen Bai province, Vietnam. The used tools for processing data is a combination of two free software, SNAP 7.0 and STaMPS 4.1. With 27 Sentinel-1A images in descending direction acquired from 11th January 2019 to 1st March 2021, the landslide displacement values were calculated and exported. There were locations in which landslides correctly appeared, such as Lang Thip, Xuan Tam, Chau Que Ha, Phong Du Thuong communes and along provincial road 151. Landslide rate is determined from SAR image series with average value less than 16.5 mm/y in places with high terrain and steep slope. The distribution of permanent scatter (PS) points for landslides often appeared along the road slopes, especially the inter-communal and inter-provincial roads that have not been reinforced with structural mitigation measures. In 2013 a field survey was conducted by the Vietnam Institute of Geosciences and Mineral Resources for this area which was used to validate the results from SAR processing. Landslide velocity charts at certain landslide sites were derived. The current study demonstrated the feasibility of the method as well as the usage of Sentinel-1 data for land deformation monitoring in the mountainous area.

Flood Inundation Analysis in Penang Island (Malaysia) Based on InSAR Maps of Land Subsidence and Local Sea Level Scenarios

Penang Island is an important economic center in Malaysia and most of its population live in the coastal areas. Although previous studies have shown that it is vulnerable to rising sea levels, the combination of sea-level rise and local land subsidence would be devastating. Therefore, the objective of this study is to apply the local land subsidence model to estimate the inundated areas which relate to sea level rise by 2100. Land subsidence is quantified by the SBAS-InSAR technique on the basis of Sentinel-1 radar images for both ascending and descending tracks. For the first time, the geostatistical analyst method is used to merge the different track results and create the land subsidence models, the results show this method can maximize land deformation fields and minimize deformation errors. According to the land deformation results, all of the coastlines in the east of the island have differing medium levels of subsidence, especially in reclaimed lands and building areas. Lastly, the bathtub model is used to quantify the inundated areas by combing regional sea-level rise projection and local land subsidence models under CoastalDEM in 2100 projections. The results of this study indicate land subsidence that would increase 2.0% and 5.9% of the inundated area based on the different scenarios by 2100 projections.