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Fault detection algorithms (such as advanced RAIM) developed for aviation can be applied in situations where the probabilities of fault are arbitrarily high. However, with large probabilities, the user receiver needs to protect against a large number of fault modes (which results from the combination of simultaneous independent faults). In baseline ARAIM algorithms, the user receiver must compute a fault-tolerant position solution for each fault mode (computed using the subset of the available measurements that would not be affected by the fault mode), or at least its error covariance. After showing how to use a solution separation algorithm without computing the fault-tolerant position solutions, we present a technique to obtain upper bounds on the subset error covariance for a given subset size. This upper bound does not require the computation of every subset error covariance and can be computed without additional matrix inversions. We evaluate the potential of this technique by applying it to ARAIM scenarios. [ABSTRACT FROM AUTHOR]

Integral to any authentication system is the design of its public key infrastructure (PKI), allowing the system to distribute, maintain, and revoke cryptographic keys while dividing and allocating the responsibility of security between different entities. This paper develops a PKI for two SBAS candidate authentication schemes: one each for an L5 I‐channel and Q‐channel implementation. A simulator, introduced as MCOS, is developed to enable large scale Monte Carlo tests of these PKI designs. This work concludes that once a receiver has been deployed with a set of preinstalled encrypted public keys, a strictly over‐the‐air method of delivering PKI information is feasible for SBAS data authentication in nominal conditions. This work also provides a strong candidate PKI that is designed to be standardized internationally for current and future SBAS service providers. [ABSTRACT FROM AUTHOR]

Two critical parameters for advanced receiver autonomous integrity monitoring are the probability of satellite fault and the probability of constellation fault. This paper provides specific definitions for each of these fault types. We describe how these faults are evaluated and how to estimate their probability occurrence. Providing a precise definition of what constitutes a fault is essential so that all observers are able to agree on whether or not one has occurred. [ABSTRACT FROM AUTHOR]

We present a method to determine Gaussian overbounding distributions used in integrity analysis. This method overcomes the limitations of previous techniques by combining them, through the determination of an intermediate symmetric and unimodal overbounding distribution. This method is the basis of a MATLAB toolset that computes strict Gaussian overbounding distributions for any sample distribution. We apply the method to the determination of the overbounding distribution of the GPS clock and ephemeris errors for the advanced receiver autonomous integrity monitoring. [ABSTRACT FROM AUTHOR]

Cryptography in the form of digital signatures can be part of the solution to the threat of spoofing and is going to be implemented on Galileo and other Global Navigation Satellite Systems. Digital signatures incorporated into the data stream authenticate the integrity of the data as well as the origin of the message. Implementing a digital signature on a satellite‐based augmentation system for use in aviation will require the signature to be short and the signing procedure to be cryptographically relevant for the next 30 or more years. With the advent of quantum computing, many state‐of‐the‐art authentication schemes are no longer viable, so an authentication scheme implemented in satellite‐based augmentation system will need to be quantum secure. This paper introduces the cryptographic primitives (foundational problems) necessary to understand the vulnerabilities in modern‐day cryptography due to quantum computing and investigates the use of TESLA (Timed Efficient Stream Loss‐tolerant Algorithm) and EC‐Schnorr (Elliptic Curve‐Schnorr) algorithms in broadcast systems. [ABSTRACT FROM AUTHOR]

The Wide Area Augmentation System (WAAS) achieved Initial Operating Capability (IOC) in July 2003. At IOC, WAAS had 25 reference stations in the Conterminous United States, Hawaii, Alaska, and San Juan, Puerto Rico, two master stations, and four uplink stations supporting two narrowband L1 only Geostationary Earth Orbit (GEO) satellites. Today, WAAS has 38 reference stations including four in Canada and five in Mexico, three master stations, and six uplink stations supporting three wide band L1/L5 GEO satellites. In addition to the architectural expansion, the Federal Aviation Administration (FAA) continued to evolve and maintain the algorithms, hardware, and software. With WAAS now turning 15 years of age, this paper takes stock of these modifications and details the improved service and integrity that has occurred since 2003. [ABSTRACT FROM AUTHOR]

Abstract: This paper examines how to evaluate observed instantaneous signal‐in‐space errors and determine suitable upper bounds on their likely distribution. We compare this performance against the commitments and broadcast values from the satellites to determine whether the provided values are sufficient or not. An important aspect is to characterize the errors in light of known or predictable characteristics. Oftentimes, errors are grouped together to create a single averaged distribution. However, there may be times and conditions where performance is notably worse. We need to separate out such conditions and evaluate the distributions individually so as not to form overly optimistic estimates of the error bounds. Further, we must ensure that these parameters will continue to bound future fault‐free behavior. We will describe the conservative steps taken in the estimation process and the validation effort, both with the real data and versus the stated commitments from the constellation service providers. Copyright © 2018 Institute of Navigation [ABSTRACT FROM AUTHOR]

We present a fault exclusion algorithm and a formula for the position error bounds after an exclusion event for Advanced Receiver Autonomous Integrity Monitoring. This algorithm has both a low computational load and an analytical proof of integrity. To mitigate the loss of performance associated with false exclusion, the method both exploits the ambiguity as to which measurement must be excluded and a pre-allocation of the integrity budget to the exclusion outcomes. The algorithm is evaluated for a GPS-Galileo Advanced RAIM scenario. We show that with this algorithm, the addition of the exclusion option does not impact the protection levels compared to detection only and that when the faults are large enough, the effect on the user is equivalent to the effect of an outage. Copyright © 2017 Institute of Navigation [ABSTRACT FROM AUTHOR]

This paper describes an efficient new algorithm being developed for the Wide Area Augmentation System (WAAS) that significantly improves its ability to detect threats arising from multiple simultaneous one to two sigma errors. This new algorithm is based on the sum of the squares of the normalized errors at each reference station. It has significantly improved the ability to detect error conditions that are not obviously faulted individually, but that could be harmful to users when combined. Currently, other monitors are inflating the confidence bounds to protect against such conditions. This new User Position Monitor (UPM) is able to identify such threats, and as a consequence, excess conservatism may be removed from the system. We expect this innovation to lead to better availability while maintaining equal or better levels of integrity. Copyright © 2017 Institute of Navigation [ABSTRACT FROM AUTHOR]

One of the most commonly used detection statistics in autonomous integrity monitoring is the solution separation statistic. In this paper, we show that the solution separation statistic is closely linked to the optimal detection statistics. More precisely, we show that in the case of one threat, even multi-dimensional, the optimal detection statistic is the solution separation, and that in the case of many one-dimensional threats, the optimal statistics can be expressed as a function of the solution separations corresponding to each threat. This is achieved by casting the search of the optimal detection region as a mini-max problem and by using the Neyman-Pearson lemma to limit the search of the detection regions to a class of regions parameterized by a bias. These results allow us to establish a lower bound on the minimum achievable integrity risk. Copyright © 2017 Institute of Navigation [ABSTRACT FROM AUTHOR]

Growing activity in the Arctic calls for high integrity navigation in this region. This can be achieved using Global Navigation Satellite Systems (GNSS) in conjunction with Satellite Based Augmentation Systems (SBAS) or Advanced Receiver Autonomous Integrity Monitoring (ARAIM). Single frequency GPS-only SBAS is in service in some regions today and is reliant on ground and space infrastructure. ARAIM will be more autonomous and will rely on the multitude of signals and core constellations coming in the future. Here, we examine both SBAS and ARAIM in the context of aviation and maritime requirements in the Arctic. Results demonstrate that the introduction of multi-frequency and multi-constellation to these systems enables navigation safety in the Arctic. SBAS brings aircraft precision approach as well as precise maritime operations such as mapping. ARAIM also supports precision approach in addition to autonomous ice navigation at sea but falls short of precision maritime requirements. Copyright © 2016 Institute of Navigation [ABSTRACT FROM AUTHOR]

We describe a simple method to determine a Global Navigation Satellite System (GNSS) position estimator for advanced receiver autonomous integrity monitoring (RAIM) that improves availability upon the commonly used least squares estimator. The idea consists in searching the estimator among all affine combinations of the all-in-view least squares estimator and a fault-tolerant estimator?the one corresponding to the most difficult fault to mitigate. Availability simulations show a significant improvement in vertical guidance coverage levels for a dual constellation scenario. [ABSTRACT FROM PUBLISHER]

ABSTRACT We present a method to improve the integrity error bound in Advanced RAIM by optimizing the position solution and the integrity allocation simultaneously. Since the reduction in the error bound is achieved by degrading the position accuracy under nominal conditions, the method takes into account the accuracy constraint in the optimization. Advanced RAIM may have to consider a larger number of satellites and increased probabilities of fault, so this method is designed to accept a wide variety of threat models (in particular multiple faults). The search of the optimal coefficients is cast as a convex optimization problem with constraints. The solution is obtained iteratively, and the convexity of the problem guarantees a very fast convergence. The algorithm is evaluated by comparing its performance with algorithms where the position solution is not optimized, and showing how it could help achieve worldwide coverage of vertical guidance (LPV-200). Copyright © 2013 Institute of Navigation [ABSTRACT FROM AUTHOR]

ABSTRACT The GNSS environment is experiencing two major changes: the introduction of a new civil signal in the L5 band and the launch of new GNSS constellations. These improvements could enable worldwide vertical guidance using Advanced Receiver Autonomous Integrity Monitoring (ARAIM). Before ARAIM can be implemented, it will be necessary to develop a common understanding across service providers of the navigation requirements, the threat model, the airborne algorithm, and the role of ground monitoring. We outline a concept for the provision of integrity based on ARAIM. First, an interpretation of vertical guidance (LPV-200) requirements is proposed. Then, we describe a comprehensive threat model for GNSS which includes both nominal performance and faulted behavior. We will show how the threats could be mitigated through the use of ground monitoring and the Integrity Support Message in addition to the ARAIM airborne algorithm. Finally, examples of constellation configurations providing worldwide coverage of LPV-200 are presented. Copyright © 2013 Institute of Navigation. [ABSTRACT FROM AUTHOR]

ABSTRACT GPS has launched its first L5 capable satellites and plans to achieve L5 Full Operational Capability (FOC) in the 2019 time frame. L5 is of great interest to the Wide Area Augmentation System (WAAS) and the aviation community, as it will allow aircraft to measure and remove the ionospheric delay affecting each ranging observation. Currently, this error source is the most significant cause of unavailability for WAAS users. Its elimination will result in greater performance and a larger service area under WAAS. However, in order to take advantage of L5, both the aircraft and WAAS will need to be updated. We have previously recommended changes to the airborne protection level calculations to exploit these new signals. In this paper we describe changes that should then be made to WAAS to support the new protection level equations and provide dual-frequency service. Copyright © 2012 Institute of Navigation [ABSTRACT FROM AUTHOR]

Abstract: Deep and frequent Global Positioning System (GPS) signal fading due to strong ionospheric scintillation is a major concern for GPS-guided aviation in equatorial areas during high solar activity. A GPS aviation receiver may lose carrier tracking lock under deep fading, and a lost channel cannot be used for position calculation until lock is reestablished. Hence, frequent loss of lock due to frequent fading can significantly reduce the availability of GPS aviation. However, the geometric diversity of the satellites can mitigate scintillation impact on GPS aviation depending on the correlation level of deep fades between satellites. This paper proposes a metric to measure the correlation level of two fading channels from the perspective of GPS aviation. Using this metric, the satellite-to-satellite correlation is studied based on real scintillation data. The low satellite-to-satellite correlation shown in this paper envisions notable availability benefit from the geometric diversity of satellites under strong scintillation. In addition, this paper proposes a way to generate correlated fading processes with arbitrary correlation coefficients. Using this correlated fading process model, the availability of Localizer Performance with Vertical guidance (LPV)-200 under severe scintillation scenarios is analyzed. The result emphasizes the importance of a fast reacquisition capability of an aviation receiver after a brief outage, which is not currently mandated by the aviation receiver performance standards. [Copyright &y& Elsevier]

A unaugmented Global Positioning System (GPS)-based flight inspection system (FIS) that performs airborne inspection of the instrument landing system (ILS) is introduced. This novel system relies on a TV positioning system (TVPS) that measures the horizontal position over the runway threshold and a radar altimeter (RA) to determine a reference point that is able to remove the GPS biases. Because of the near-real-time nature of flight inspection, it is possible to reconstruct an accurate approach trajectory even though the reference point occurs after the completion of the trajectory. The precise relative positioning (PRP) algorithm is applied to achieve the desired results. It includes a first-order fit to the ionospheric error, based on code and carrier measurements, that enables a significant reduction in this error source. This system has an autonomous integrity feature, called FIS-RAIM (receiver autonomous integrity monitoring), that is equipped in this system to protect against GPS satellite failures that may cause significant positioning errors. The FIS-RAIM is specifically designed for a flight inspection problem, and much of its detail is also described. Experimental flight tests strongly suggest that the system architecture and algorithm could meet FIS accuracy requirements for CAT III ILS with better performance than current flight inspection systems in terms of cost and efficiency. The system is not dependent on any GPS augmentation system; therefore the unaugmented GPS-based FIS provides low cost and high efficiency with worldwide availability. [ABSTRACT FROM AUTHOR]

In safety-of-life applications of satellite navigation, the protection level (PL) equation translates what is known about the pseudo-range errors into a reliable limit on the positioning error. The current PL equations for satellite-based augmentation systems (SBAS) rely on Gaussian statistics. This approach is very practical: the calculations are simple and the receiver computation load is small. However, when the true distributions are far from Gaussian, such a characterization forces an inflation of the PLs that degrades performance. This happens in particular with errors with heavy tail distributions or for which there is not enough data to evaluate the distribution density up to small quantiles. We present a way of computing the optimal protection level when the pseudo-range errors are characterized by a mixture of Gaussian modes. First, we show that this error characterization adds a new flexibility and helps account for heavy tails without losing the benefit of tight core distributions. Then, we state the positioning problem using a Bayesian approach. Finally, we apply this method to PL calculations for the wide area augmentation system (WAAS) using real data from WAAS receivers. The results are very promising: vertical PLs are reduced by 50% without degrading integrity. [ABSTRACT FROM AUTHOR]

The Federal Aviation Administration's augmentation to the global positioning system for civil aviation is called the wide area augmentation system. This paper introduces the wide area augmentation system-based flight inspection system. This system is better optimized than the current flight inspection systems in terms of accuracy, cost, and efficiency. Although they meet the Federal Aviation Administration's flight inspection system accuracy requirements, the current flight inspection systems are either higher cost or less efficient. The innovative use of the wide area augmentation system with a radar altimeter and a television positioning system without a requirement for an inertial navigator makes it possible for the wide area augmentation system-based flight inspection system to have low cost and high efficiency in flight inspection for instrument landing system calibration. The wide area augmentation system-based flight inspection system meets the Federal Aviation Administration's accuracy requirements for CAT III ILS calibration and also provides firm integrity algorithms. The performance of the wide area augmentation system-based flight inspection system is confirmed with tests using flight data taken in collaboration with the Federal Aviation Administration. [ABSTRACT FROM AUTHOR]

Here we delineate a complete satellite-based augmentation system (SBAS) authentication scheme, including over-the-air rekeying (OTAR), that uses the elliptic curve digital signature algorithm (ECDSA) and timed efficient stream loss-tolerant authentication (TESLA) without the quadrature (Q) channel. This scheme appends two new message types to the SBAS scheduler without overburdening the message schedule. We have taken special care to ensure that our scheme (1) meets the appropriate security requirements needed to prevent and deter spoofing; (2) is compatible with existing cryptographic standards; (3) is flexible, expandable, and future-proof to different cryptographic and implementation schemes; and (4) is backward compatible with legacy receivers. The scheme accommodates a diverse set of features, including authenticating core-constellation ephemerides. We discuss the SBAS provider and receiver machine state and its startup, including its use by aircraft that traverse differing SBAS coverage areas. We tested our scheme with existing SBAS simulation and analysis tools and found that it had negligible effects on current SBAS availability and continuity requirements. [ABSTRACT FROM AUTHOR]

Abstract: There has been resurgent interest in building low Earth orbiting (LEO) constellations of satellites on a new scale. Their aim is Internet for the world with plans for potentially thousands of satellites. Here, we explore how these LEO constellations can be utilized for navigation. Closer to Earth, LEO offers stronger signals, strengthening us against jamming and aiding in indoor and urban environments. Proximity is also its weakness, where satellites have a small Earth footprint requiring many to provide global coverage. We show that the strength of the Broadband LEO constellations is their numbers, where they offer threefold improvement in satellite geometry compared to navigation core‐constellations today. This allows for relaxation of the signal‐in‐space user range error, while still matching the position accuracy of GPS. Coupled with the more benign radiation environment in LEO compared to GPS in medium Earth orbit, this enables a navigation payload designed using commercial‐off‐the‐shelf components. © 2018 Institute of Navigation [ABSTRACT FROM AUTHOR]

Strong ionospheric scintillation due to electron density irregularities inside the ionosphere is commonly observed in the equatorial region during solar maxima. Strong amplitude scintillation causes deep and frequent Global Positioning System (GPS) signal fading. Since GPS receivers lose carrier tracking lock at deep signal fading and the lost channel cannot be used for the position solution until reacquired, ionospheric scintillation is a major concern for GPS aviation in the equatorial area. Frequent signal fading also causes frequent reset of the carrier smoothing filter in aviation receivers. This leads to higher noise levels on the pseudo-range measurements. Aviation availability during a severe scintillation period observed using data from the previous solar maximum is analyzed. The effects from satellite loss due to deep fading and shortened carrier smoothing time are considered. Availability results for both vertical and horizontal navigation during the severe scintillation are illustrated. Finally, a modification to the upper bound of the allowed reacquisition time for the current Wide Area Augmentation System (WAAS) Minimum Operational Performance Standards (MOPS) is recommended based on the availability analysis results and observed performance of a certified WAAS receiver. [ABSTRACT FROM PUBLISHER]

Among the receiver autonomous integrity monitoring (RAIM) algorithms treating multiple failures, multiple hypothesis solution separation algorithms (MHSS)—a type of solution separation algorithm—offer several advantages: First, the link between threat model, upper bound on the position error—the protection level and probability of hazardously misleading information is an easy and straightforward one; second, the calculation of the protection level does not involve complex steps. One of the critical steps in this algorithm is the allocation of the integrity and continuity budgets among the failure modes, as it determines the overall performance of the algorithm. After describing the baseline MHSS approach, we present an algorithm that simultaneously allocates the integrity and continuity budget among the failure modes to obtain the minimum protection level per satellite geometry. Then, we show how slope-based RAIM and solution separation RAIM are related through a little-known formula, which both unifies and highlights the differences between the two approaches. Finally, we apply the algorithm to evaluate the performance of RAIM for vertical guidance for a dual constellation, and find that even with a very large prior probability of satellite failure, vertical guidance can be achieved worldwide with high availability. [ABSTRACT FROM AUTHOR]

Techniques available to sustain dual-frequency ionosphere performance when a dual-frequency airborne Global Positioning System (GPS)/wide area augmentation system (WAAS) user loses all but one GPS frequency while descending into radio frequency interference (RFI) are investigated. We are particularly interested in the case where the user transitions from L1–L5 to having L5-only since the uncertainty of the L5-only ionospheric delay estimation is larger than the case for L1-only. The goal is to provide the techniques necessary for single-frequency users to sustain a performance similar to those of dual-frequency users. The proposed techniques are 1) the code and carrier divergence technique, 2) the WAAS ionosphere threat model technique, and 3) the maximum ionospheric delay gradient model technique. The results show that all three proposed techniques provide good ionospheric delay estimation for the full duration of approach. [ABSTRACT FROM PUBLISHER]

Satellite-based augmentation systems ensure the accuracy and integrity of aircraft position estimates derived from radio signals broadcast by the Global Navigation Satellite System. The United States' Wide Area Augmentation System (WAAS) protects users of the Global Positioning System from threats generated by ionospheric disturbances. The means by which WAAS mitigates these threats depends upon their magnitude. This paper addresses: a) how WAAS monitors the level of ionospheric perturbation over North America; b) how various availability and integrity concerns have influenced the implementation of WAAS's extreme and moderate ionospheric storm detectors; c) how the algorithms governing these implementations have evolved since WAAS's commissioning in 2003; and d) how the largest ionospheric storms of the past two solar cycles can be ranked according to their impact on WAAS. A subsequent companion paper will address the evolution of the WAAS methodology for protecting users from the adverse influence of more moderate ionospheric disturbances. [ABSTRACT FROM AUTHOR]

We present a framework for GNSS spoofing detection combining an arbitrary number of metrics while guaranteeing a fixed maximum false alert probability. The detection test assumes a simple form that makes it suitable for real time applications. We define criteria for metrics to be used within this framework and demonstrate compatibility with a range of commonly used metrics. We achieve a more than 70% reduction in worst-case missed detection probability compared to conventional metric combination techniques. [ABSTRACT FROM AUTHOR]

Knowledge of the Global Positioning System (GPS) signal-in-space (SIS) anomalies in history has a great importance for not only assessing the general performance of GPS SIS integrity but also validating the fundamental assumption of receiver autonomous integrity monitoring (RAIM): at most one satellite fault at a time. The main purpose of this paper is to screen out all potential SIS anomalies in the last decade by comparing broadcast ephemerides and clocks with precise ones. Validated broadcast navigation messages are generated from 397,044,414 navigation messages logged by on average 410 International GNSS Service (IGS) stations during the period 6/1/2000?8/31/2010. Both IGS and National Geospatial-Intelligence Agency (NGA) precise ephemerides/clocks are used as truth references. Finally, 1256 potential SIS anomalies are screened out. These anomalies show an improving SIS integrity performance in the last decade, from tens or hundreds of anomalies per year before 2003 to on average two anomalies per year after 2008. Moreover, the fundamental assumption of RAIM is valid because never have two SIS anomalies or more occurred simultaneously since 2004. [ABSTRACT FROM AUTHOR]

This paper develops an empirical confidence bound for barometric altimeter altitude errors and shows how this bound may improve the performance of GPS-based approach and landing systems. This empirical bound is developed using historical meteorological data collected at a set of geographically diverse locations over a thirty year period. The confidence bound developed is shown to provide a Gaussian overbound on altimeter altitude errors in standard atmospheric conditions between a 10-5 and 10-6 confidence level. This confidence bound is integrated into the standard methodology for analyzing the performance of GPS-based landing systems and the results of a performance trade study using the confidence bound are presented. The results show that incorporating the empirical barometric altimeter confidence bound provides an increase in the coterminous United States (CONUS) service volume for lateral precision with vertical guidance (LPV) type approaches. While this increase is approximately 2% for an L1 single-frequency GPS user, it jumps to roughly 40% for an L5 single-frequency user. [ABSTRACT FROM AUTHOR]

In this paper, we present an algorithmic framework for signal‐geometry‐based approaches of GNSS spoofing detection. We formulate a simple vs. simple hypothesis test independent of nuisance parameters that results in significantly reduced missed detection probability compared to prior approaches. It is highly tractable such that it can be computed online by the receiver. We employ a hypothesis iteration framework that finds spoofed subsets of satellites efficiently and accounts for the presence of weak multipath, for a provable decision behavior in safety‐of‐life applications. We support the theoretical derivations by showing results on previously published simulated and on‐air data sets. We validate the measurement model and show robustness to multipath with flight data from a Dual Polarization Antenna (DPA) mounted on a C12 aircraft. Finally, we show the algorithm's benefit on data recorded during a government‐sponsored live spoofing event. [ABSTRACT FROM AUTHOR]

Abstract This study applies a novel landscape approach to empirically assess the linkage between terrestrial landscape alteration such as urbanization and aquatic ecosystem degradation from a hydrological sensitive area (HSA) perspective in 141 selected northern New Jersey watersheds. HSAs are hydrological "hotspots" in a watershed that actively contribute to runoff generation and were delineated using a soil topographic index. Land use metrics captured landscape alterations in terms of percentages of varying land uses in these watersheds and their HSAs. Aquatic ecosystem integrity was represented by a High Gradient Macroinvertebrate Index (HGMI) specifically developed for the stream types assessed in this study. Multiple linear regression (MLR) analysis was used to understand the relationships between land use metrics and HGMI score at the watershed- and HSA-scales and a data fitting procedure called Least Absolute Shrinkage and Selection Operator (LASSO) was used to identify the most statistically significant land use attributes to be retained in the MLR models. The modeling results at the HSA-scale showed more parsimonious and robust relationships between landscape alteration and aquatic integrity than at the watershed-scale in terms of both variable selection and statistical inference. While high intensity urbanization is a known stressor that can significantly degrade aquatic ecosystem integrity, the results indicate that landscapes developed more strategically by way of low intensity urbanization (e.g., rural residential) or on less hydrologically sensitive areas may lessen the detrimental effects of urbanization on aquatic ecosystem integrity. These findings support the premise that it is not just the extent of urbanization in a watershed that matters, but also the intensity and location of the disturbance on the landscape that affects aquatic ecosystem integrity. Such findings may encourage more flexible landscape planning and management practices that better protect HSAs from urban development in support of long-term aquatic ecosystem protection and restoration. Graphical abstract Unlabelled Image Highlights • Landscape change in hydrological hotspots has disproportionate impact on stream integrity. • Urban lands with high development intensity negatively affect stream integrity. • Deliberately managed urban landscape has potential of improving stream integrity. • Forest preservation is the most effective policy to improve stream integrity. • LASSO is a powerful tool for effective multiple linear regression modeling. [ABSTRACT FROM AUTHOR]