ORCID Profile
0000-0001-5463-8307
Current Organisations
Deakin University
,
The University of Newcastle
Does something not look right? The information on this page has been harvested from data sources that may not be up to date. We continue to work with information providers to improve coverage and quality. To report an issue, use the Feedback Form.
Publisher: Elsevier BV
Date: 06-2022
DOI: 10.1016/J.WATRES.2022.118487
Abstract: During the Millennium Drought in southeast Australia (2001-2009), dryland wetlands experienced widespread ecological deterioration, which highlighted their vulnerability to natural climate variability and the potential effects of drying climate change. Here we use 30-year observed streamflow data (1991-2020) and numerical models to assess the impacts of climate variability and climate change on the Macquarie Marshes (the Marshes), a large floodplain wetland complex in the semi-arid region of New South Wales, Australia. A fast ecohydrologic emulator based on network linear programming with side constraints was developed to simulate the spatial and temporal responses of different wetland vegetation types to water regime. The emulator represents the wetland by a series of inter-connected level-pool reservoirs with the volume-discharge relationship obtained from a calibrated quasi-2d hydrodynamic model. The emulator reproduces daily flows and volume with good accuracy (Nash-Sutcliffe statistic ranging from 0.61 to 0.96) with 1/26,000 of the computational effort. We use the emulator to simulate the potential effects of climatic variability on vegetation by running the model over 30 years of observed data and 1000 statistically representative 30-year streamflow time series, which were generated using a stochastic model calibrated to the gauged flows. The collection of results for all 1000 contemporary simulations indicates the Marshes experience severe conditions 43% (± 18%) of the time in a 30-year period. We then ran an additional 6000 simulations to assess the combined impacts of climate variability and future climate change at the end of the century. For the driest future climates (-60% and -30% reduction in runoff), the Marshes remain in severe condition 89% (± 6%) and 63% (± 16%) of the time, respectively, while no major differences with respect to the contemporary conditions were found for the wetter future. Our results highlight the importance of quantifying the extent and uncertainty in the degradation of these ecosystems due to climate variability and change for informing management decisions.
Publisher: Copernicus GmbH
Date: 14-09-2020
Publisher: Copernicus GmbH
Date: 23-03-2020
DOI: 10.5194/EGUSPHERE-EGU2020-11476
Abstract: & & Over the last two decades, there have been important advances in eco-geomorphological modelling of coastal wetlands to predict their evolution. Different features have been incorporated into models, bust most applications still assume a constant or static sediment concentration as input representing average conditions. Such imposition is related to many constraints in obtaining a time series of total suspended matter (TSM). However, with the increasing availability of multispectral satellite products and the development of artificial intelligence algorithms, TSM data can be estimated through remote sensing. This work aims to assess the effect of using a dynamic time varying condition for the TSM input when simulating eco-geomorphological processes. We implemented a modelling framework adapted to conditions found in SE Australian estuaries, which includes hydrodynamic and sediment transport processes. Many scenarios where simulated encompassing different levels of average TSM and water levels. Our findings suggest that under low water levels and low sediment concentration, a static TSM input results in more accretion than a dynamic input. However, at higher levels and concentration, the dynamic input led to higher accretion. Predictions of vegetation distribution were not particularly sensitive to changes in TSM over time.& &
Publisher: Copernicus GmbH
Date: 23-03-2020
DOI: 10.5194/EGUSPHERE-EGU2020-619
Abstract: & & Pacific Islands are one of the regions in the world most vulnerable to climate change, mainly due to sea level rise (SLR) and tropical cyclones (TC). Coastal wetlands play a crucial role as a buffer between the ocean and the inland areas. Recent research has shown that accretion and adaptation capacity to SLR of coastal wetlands is intrinsically related to the sediment supply from the upstream catchments and the tidal regime, which is also affected by the hydrodynamic and the vegetation of the system. Modelling the feedback among these systems and their evolution is still challenging.& & & & In this work, we present the case of a coastal wetland at the mouth of Dreketi River catchment, located in Vanua Levu, Fiji. This area belongs to the Great Sea Reef, and it was declared as Ramsar site in 2018. The framework proposed includes the modelling of hydro-sedimentological behaviour of the upstream catchment and its validation using remotely sensed images and the hydrodynamic-sediment transport model of the tides. These outputs are linked with an ecogeomorphological model (EGM) of the mangrove wetlands used to predict wetland evolution. We have evaluated the catchment response under current scenarios assessing the impact of TC in the last 45 years and under future scenarios of land use, TC and SLR. We have analysed the same scenarios on the tidal system to then run the EGM incorporating the changes in sediment supply from both the catchments and the tides due to SLR and TC projected by the end of the century.& Our approach combining modelling and remote sensing can be extended to other coastal areas in the region and has enormous potential to assess the evolution of wetlands under climate change throughout the Pacific islands.& &
Publisher: Copernicus GmbH
Date: 04-03-2021
DOI: 10.5194/EGUSPHERE-EGU21-13953
Abstract: & & Coastal wetland are known to be among the most efficient carbon burial environments around the worlds and given this high efficiency for carbon sequestration, wetland restoration and conservation efforts have been proposed as a way to potentially mitigate greenhouse emissions. The processes that lead to carbon sequestration can be quite complex and often depend on feedbacks between the type of vegetation in the wetlands, tidal flow regime, geomorphology and sediment availability. Coastal wetland vulnerability to submergence due to sea-level rise has been widely discussed in the current literature, and while wetlands could survive under some sea-level rise scenarios, accelerated rates of sea-level rise would most likely result in significant wetland losses. These can be less accentuated when accommodation space is available and the wetland is able to migrate inland, however, topography, physical barriers, and some anthropogenic factors can limit wetland migration thus decreasing the ability of wetlands to cope with sea-level rise. Potential losses of wetland vegetation under accelerated sea-level rise and limited capacity for wetlands to migrate inland are expected to affect the overall efficiency for carbon sequestration. We apply an eco-geomorphic model to simulate vegetation dynamics, carbon accumulation and overall change in carbon stocks for a restored mangrove-saltmarsh wetland experiencing accelerated sea-level rise under different management scenarios. Our results suggest that under accelerated sea-level rise and limited space for inland migration, vegetation might not be able to fully mature, reducing the capacity for sequestering carbon over time.& &
Publisher: Authorea, Inc.
Date: 13-09-2023
Publisher: Copernicus GmbH
Date: 04-03-2021
DOI: 10.5194/EGUSPHERE-EGU21-14057
Abstract: & & Changes in hydro-geomorphic connectivity have been previously linked to catastrophic shifts in landscape structures and function leading to irreversible degradation. Here we present evidence and new observations to better understand the link between connectivity of water and sediments and possible phase transitions for the case of semiarid ecosystems at the catchment and hillslope scales. & We first focus on rangelands, where coevolving vegetation and landform structures lead to a distinct connectivity pattern responsible for the healthy functioning of the system. Positive feedbacks, triggered by disturbances in vegetation, water or sediment structures can alter the hydro-geomorphic connectivity leading to degradation. Our results for rangelands in Australia, from both simulations and observations, suggest that an increase in connectivity beyond a threshold may lead to irreversible degradation, meaning that the system return to a functional state is unlikely without extensive management interventions. We also analyse the case of semi-arid floodplain wetlands of the Murray-Darling Basin, where we observe that dis-connectivity during droughts promote terrestrial vegetation encroachment and degradation. Simulations and observations also indicate the presence of thresholds beyond which the recovery of the system is unlikely without interventions.& &
Publisher: The Royal Society
Date: 04-08-2021
Abstract: The frequency and intensity of natural hazards and extreme events has increased throughout the last century, resulting in adverse socioeconomic and ecological impacts worldwide. Key factors driving this increase include climate change, the growing world population, anthropogenic activities and ecosystem degradation. One ecologically focused approach that has shown potential towards the mitigation of these hazard events is the concept of nature's contributions to people (or NCP), which focuses on enhancing the material and non-material benefits of an ecosystem to reduce hazard vulnerability and enhance overall human well-being. Soils, in particular, have been identified as a key ecosystem component that may offer critical hazard regulating functionality. Thus, this review investigates the modulating role of soils in the regulation of natural hazards and extreme events, with a focus on floods, droughts, landslides and sand/dust storms, within the context of NCP. This article is part of the theme issue ‘The role of soils in delivering Nature's Contributions to People’.
Publisher: American Geophysical Union (AGU)
Date: 27-08-2021
DOI: 10.1029/2020EF001901
Abstract: Estimates of global carbon stocks in coastal wetlands reveal that these are some of the most efficient carbon‐sequestering environments in the world, which has prompted a renewed interest in conservation and restoration programs as an opportunity for greenhouse gas abatement. Accumulation of carbon in coastal wetlands is linked to erse factors such as the type of vegetation, geomorphic setting, and sediment supply. Feedbacks between these factors and the tidal flow conditions drive the dynamics of carbon accumulation rates. Climate change‐induced sea‐level rise has been shown to increase the vulnerability to submergence of saltmarsh and mangroves in coastal wetlands, even if accommodation and landward colonization are possible. These potential losses of wetland vegetation combined with the reduced productivity of newly colonized areas will directly affect the capacity of the wetlands to sequester carbon from sediments and root growth. Here, we implement an eco‐geomorphic model to simulate vegetation dynamics, soil carbon accumulation, and changes in soil carbon stock for a restored mangrove‐saltmarsh wetland experiencing accelerated sea‐level rise. We evaluate model outcomes for existing conditions and two different management scenarios aimed at mitigating sea‐level rise effects and conserve wetland vegetation. Even though some management measures can result in partial conservation of wetland vegetation, they do not necessarily result in the best option for soil carbon capture. Our results suggest that accelerated sea‐level can trigger accelerated wetland colonization resulting in wetland areas with limited opportunities for soil carbon capture from sediment and root mineralization, an issue that has not been considered in previous studies.
Publisher: Wiley
Date: 29-07-2021
Publisher: CSIRO Publishing
Date: 09-11-2021
DOI: 10.1071/MF21233
Abstract: Climatically driven perturbations (e.g. intense drought, fire, sea surface temperature rise) can bring ecosystems that are already stressed by long-term climate change and other anthropogenic impacts to a point of collapse. Recent reviews of the responses of Australian ecosystems to climate change and associated stressors have suggested widespread ecosystem collapse is occurring across multiple biomes. Two commonly cited case studies concern forested wetland ecosystems: mangrove forest dieback in northern Australia (2015–16) and riverine forest dieback in the south-east of the continent (2002–09). We present an alternative interpretation that emphasises the dominant signal of climate change effects, rather than the interdecadal signal of climate variability that drives wetland forest dynamics. For both the south-east Australian riverine forests and mangroves of northern Australia, aerial extent remains greater after dieback than in the early 1990s. We interpret dieback and defoliation in both systems as a dry phase response and provide evidence of a current and near-future climate change trajectory of increased areal extent and cover (i.e. tree colonisation and range infilling). In both case studies, climate change-driven increases in tree cover and extent are occurring at the expense of wetland grasslands and the important ecosystem functions they support.
Publisher: Copernicus GmbH
Date: 28-03-2022
DOI: 10.5194/EGUSPHERE-EGU22-11009
Abstract: & & Environmental water is indispensable for promoting and maintaining environmental assets in managed catchments. Water in the Macquarie Catchment is managed by releases from Burrendong Dam, which has played an important role supplying water needs in the Macquarie Valley, and environmental flows to the Ramsar listed Macquarie Marshes. Management decisions tools are necessary to analyze impacts of environmental water at a catchment scale and are critical to preserve ecosystems services under future uncertainties of climate variability and change. Here we implemented WATHNET5, a Network Linear Programming (NLP) tool to analyze effects of environmental water in the Macquarie Catchment. Our semi-distributed model includes storage areas (Dam and wetlands), input flows of the main tributary rivers, irrigation and water consumption demands, routing and conveyance losses. For model setup, rules for operation of the dam were adjusted to current conditions, while tributary rivers, irrigation and water consumption demands were obtained from a hydrological model used by local authorities for the Macquarie River. The ecological outputs of environmental releases were assessed at five locations along the river and following the objectives provided in the Long-Term Water Plan determined by the Environmental Authority (EA). In each of the five locations, our model computed different flows Base Flows (BF), Small Fresh (SF), Large Fresh (LF) and Overbank flows (OS, OM and OL for small, medium and large respectively), which are associated to different environmental objectives. The EA determined minimum thresholds for each of the flows in terms of timing, duration, frequency and interval between events as indicators of environmental objectives compliance. Our model determines if the different flows met the thresholds and computes the amount for time that the conditions are met during the simulation period. Calibration of the flows over a 30-year period were carried out and the NLP model results were compared with the observations in five gauging station along the catchment. We found that the model adequately represents the flows with Nash& #8211 Sutcliffe efficiency coefficients between 0.42 and 0.6. Simulations were carried out for 120 years to analyze the effect of environmental water releases on ecological outcomes compared to natural condition (no dam and irrigation), showing tradeoffs between the different types of flows in different parts of the catchment. Our NLP model can be used as a multi-objective optimization tool to help identify long-term management decisions that can improve system resilience and protect environmental assets under an uncertain future climate.& &
Publisher: Springer Science and Business Media LLC
Date: 06-08-2020
DOI: 10.1038/S41598-020-70087-X
Abstract: Dryland wetlands are resilient ecosystems that can adapt to extreme periodic drought–flood episodes. Climate change projections show increased drought severity in drylands that could compromise wetland resilience and reduce important habitat services. These recognized risks have been difficult to evaluate due to our limited capacity to establish comprehensive relationships between flood–drought episodes and vegetation responses at the relevant spatiotemporal scales. We address this issue by integrating detailed spatiotemporal flood–drought simulations with remotely sensed vegetation responses to water regimes in a dryland wetland known for its highly variable inundation. We show that a combination of drought tolerance and dormancy strategies allow wetland vegetation to recover after droughts and recolonize areas invaded by terrestrial species. However, climate change scenarios show widespread degradation during drought and limited recovery after floods. Importantly, the combination of degradation extent and increase in drought duration is critical for the habitat services wetland systems provide for waterbirds and fish.
Publisher: Copernicus GmbH
Date: 15-05-2023
DOI: 10.5194/EGUSPHERE-EGU23-15132
Abstract: Assessment of coastal wetland resilience under rising sea levels using models is challenging due to uncertainties in processes and external drivers. In addition, a number of assumptions and simplifications are required in order to be able to carry out long-term complex simulations that include processes over a wide range of time and spatial scales. Some of those simplifications can have important implications for the assessment of wetland resilience. In this contribution we look at a number of simplifications typically used in coastal wetland evolution models, and we try to quantify their effects on the results. We include simplifications related to hydrodynamics, sediment transport and vegetation dynamics focusing on issues of process description, process interactions and spatial and temporal discretisation. We pay special attention to the identification of methods that include a level of simplification that allows for efficient computation with acceptable margins of error. We apply our model to a number of coastal wetlands worldwide with a variety of settings in terms of vegetation, tidal conditions, sediment load and find that accelerated sea-level rise towards the end of the century will greatly compromise wetland resilience.
Publisher: Springer Science and Business Media LLC
Date: 12-01-2021
Publisher: Elsevier BV
Date: 06-2019
Publisher: EDP Sciences
Date: 2018
DOI: 10.1051/E3SCONF/20184002019
Abstract: The Macquarie Marshes is a freshwater wetland system located in semiarid Australia. The ecological importance of this site has been recognized under the Ramsar convention. Plant associations in the marshes has shown a complex dynamic where some wetland vegetation patches have transitioned to terrestrial vegetation during severe drought, but also quickly responded to increased inflows due to record and near record rainfall accompanied by water releases from an upstream reservoir. Management decisions regarding the environmental flows require the use of predictive tools in order to assess the response of the vegetation. We have developed a vegetation response model that couples hydrodynamic modelling of the northern Macquarie Marshes with watering requirements of different plant associations and vegetation succession rules. The model simulates floods in the wetland during a series of years, after which patches of vegetation are analysed according to water depth, percent exceedance time and frequencies of inundation. During the simulated period, the patch can have adequate watering conditions, or it can have critical conditions that would lead to a succession to another type of vegetation. The predicted vegetation is reintroduced in the model, providing feedbacks for the next simulation period. In this contribution, we implemented the model to simulate changes of wetland understory during the period 1991 to 2014.
Publisher: Copernicus GmbH
Date: 04-03-2021
DOI: 10.5194/EGUSPHERE-EGU21-14219
Abstract: & & Predictions of the effects of sea-level rise over the next century on coastal wetlands vary widely due to uncertainties on environmental variables, but also due to simplifications on the simulation methodologies used. Here, we investigate how accretion and migration processes affect wetland response to sea level rise (SLR) using a computational framework that includes all relevant hydrodynamic, sediment transport and vegetation dynamics mechanisms that affect wetland evolution, and it is efficient enough computationally to allow the simulation of long time periods. We apply this framework to different settings typically found in coastal wetlands around the world, comprising different vegetation types, different sediment loads, obstructions to flow and drainage structures, both natural and man-made. We find that the vast majority of wetland settings analysed are unable to cope with high SLR rates and disappear before the end of the century. Our findings are consistent with paleo-records that indicate limits on the accretion capacity of coastal wetlands during periods of high SLR rates.& &
Publisher: Elsevier BV
Date: 03-2020
Publisher: Copernicus GmbH
Date: 18-02-2020
Abstract: Abstract. The vulnerability of coastal wetlands to future sea-level rise (SLR) has been extensively studied in recent years, and models of coastal wetland evolution have been developed to assess and quantify the expected impacts. Coastal wetlands respond to SLR by vertical accretion and landward migration. Wetlands accrete due to their capacity to trap sediments and to incorporate dead leaves, branches, stems and roots into the soil, and they migrate driven by the preferred inundation conditions in terms of salinity and oxygen availability. Accretion and migration strongly interact, and they both depend on water flow and sediment distribution within the wetland, so wetlands under the same external flow and sediment forcing but with different configurations will respond differently to SLR. Analyses of wetland response to SLR that do not incorporate realistic consideration of flow and sediment distribution, like the bathtub approach, are likely to result in poor estimates of wetland resilience. Here, we investigate how accretion and migration processes affect wetland response to SLR using a computational framework that includes all relevant hydrodynamic and sediment transport mechanisms that affect vegetation and landscape dynamics, and it is efficient enough computationally to allow the simulation of long time periods. Our framework incorporates two vegetation species, mangrove and saltmarsh, and accounts for the effects of natural and manmade features like inner channels, embankments and flow constrictions due to culverts. We apply our model to simplified domains that represent four different settings found in coastal wetlands, including a case of a tidal flat free from obstructions or drainage features and three other cases incorporating an inner channel, an embankment with a culvert, and a combination of inner channel, embankment and culvert. We use conditions typical of south-eastern Australia in terms of vegetation, tidal range and sediment load, but we also analyse situations with 3 times the sediment load to assess the potential of biophysical feedbacks to produce increased accretion rates. We find that all wetland settings are unable to cope with SLR and disappear by the end of the century, even for the case of increased sediment load. Wetlands with good drainage that improves tidal flushing are more resilient than wetlands with obstacles that result in tidal attenuation and can delay wetland submergence by 20 years. Results from a bathtub model reveal systematic overprediction of wetland resilience to SLR: by the end of the century, half of the wetland survives with a typical sediment load, while the entire wetland survives with increased sediment load.
Publisher: CRC Press
Date: 12-08-2014
DOI: 10.1201/B17133-313
Publisher: Copernicus GmbH
Date: 15-05-2023
DOI: 10.5194/EGUSPHERE-EGU23-10976
Abstract: Arid and semi-arid ecosystems are under the pressure of climate change and are facing overgrazing and logging, which has led to increased degradation and desertification processes. The Drylands of Mendoza, Argentina, are fragile ecosystems devoted to cattle breeding on native bushes and rangelands. Livestock farming relies on the productivity of natural resources, closely related to the monthly, annual, and seasonal rainfall, which is a critical driver of vegetation productivity and dynamics. This study aims to determine the relationship between NDVI and Accumulated Antecedent Precipitation (AAP) in natural dryland as a basis for decision support in cattle grazing. NDVI from MODIS-Terra (MOD13Q1 V6.1) and AAP estimated by satellite using GPM (Global Precipitation Measurement) were correlated using Pearson's Correlation Coefficient at monthly timesteps over a period of 20 years (June 2000 to May 2020) considering 0 APP (monthly) and 1, 3-, 6-, 9- and 12-months AAP. The analysis was carried out spatially (pixel-to-pixel) in 5 points of each of 4 primary vegetation types of the interest area (Bush steppe with low land cover Open Bush Forest of Prosopis Flexuosa and Psammophilious Grassland). NDVI responses to 3 months of AAP were significant for all vegetation types in the study area. Tracking vegetation responses to rainfall in this region is of outmost importance for management of the limited water resources.
Publisher: Copernicus GmbH
Date: 14-09-2020
Abstract: Abstract. The vulnerability of coastal wetlands to future sea-level rise (SLR) has been extensively studied in recent years, and models of coastal wetland evolution have been developed to assess and quantify the expected impacts. Coastal wetlands respond to SLR by vertical accretion and landward migration. Wetlands accrete due to their capacity to trap sediments and to incorporate dead leaves, branches stems and roots into the soil, and they migrate driven by the preferred inundation conditions in terms of salinity and oxygen availability. Accretion and migration strongly interact and they both depend on water flow and sediment distribution within the wetland, so wetlands under the same external flow and sediment forcing but with different configurations will respond differently to SLR. Analyses of wetland response to SLR that do not incorporate realistic consideration of flow and sediment distribution, like the bathtub approach, are likely to result in poor estimates of wetland resilience. Here, we investigate how accretion and migration processes affect wetland response to SLR using a computational framework that includes all relevant hydrodynamic and sediment transport mechanisms that affect vegetation and landscape dynamics, and it is efficient enough computationally to allow the simulation of long time periods. Our framework incorporates two vegetation species, mangrove and saltmarsh, and accounts for the effects of natural and manmade features like inner channels, embankments and flow constrictions due to culverts. We apply our model to simplified domains that represent four different settings found in coastal wetlands, including a case of a tidal flat free from obstructions or drainage features and three other cases incorporating an inner channel, an embankment with a culvert, and a combination of inner channel, embankment and culvert. We use conditions typical of SE Australia in terms of vegetation, tidal range and sediment load, but we also analyse situations with three times the sediment load to assess the potential of biophysical feedbacks to produce increased accretion rates. We find that all wetland settings are unable to cope with SLR and disappear by the end of the century, even for the case of increased sediment load. Wetlands with good drainage that improves tidal flushing are more resilient than wetlands with obstacles that result in tidal attenuation, and can delay wetland submergence by 20 years. Results from a bathtub model reveals systematic overprediction of wetland resilience to SLR: by the end of the century, half of the wetland survives with a typical sediment load, while the entire wetland survives with increased sediment load.
Publisher: Copernicus GmbH
Date: 15-05-2023
DOI: 10.5194/EGUSPHERE-EGU23-10518
Abstract: Predictions of the fate of coastal wetlands under the effects of sea-level rise (SLR) vary widely due to uncertainties on environmental variables, but also due to unavoidable simplifications in the models. Here, we present a simplified domain ecogeomorphic model that includes all relevant hydrodynamic, sedimentation and vegetation dynamics mechanisms that affect wetland evolution, it does not require detailed information and it is efficient enough computationally to allow the simulation of long time periods. We test this framework and apply it in different settings typically found in coastal wetlands around the world, comprising different geomorphic configurations, vegetation types, sediment characteristics and tidal regimes. Most of the wetland settings analysed are unable to cope with the high SLR rates expected by the end of the century, in agreement with results using paleo-records during periods of high SLR rates.
Publisher: Elsevier BV
Date: 07-2020
Publisher: Copernicus GmbH
Date: 23-03-2020
DOI: 10.5194/EGUSPHERE-EGU2020-11934
Abstract: & & Over the last few years, the concept of hydrological connectivity has emerged as a useful framework to quantify how changes in water redistribution and sediment production may lead to land degradation. Here, we illustrate the use of the connectivity framework for several ex les of dryland systems that are analysed at a variety of spatial and temporal scales using both modelling approaches and remote sensing data analysis. We show that hydrological connectivity is particularly useful in drylands where human and/or natural disturbances can alter the surface water availability and pathways, and therefore the system connectivity. In doing so, we also focus on the analysis of co-evolution of system structures and function, and how they may drive threshold behaviour leading to desertification. We apply the framework to different dryland systems, starting with the analysis of semi-arid rangelands, where feedbacks between the decline in vegetation density and landscape erosion reinforces degradation processes driven by changes in connectivity. We then focus on semi-arid floodplain wetlands, where decreases in water volumes promote terrestrial vegetation encroachment that changes drainage conditions and connectivity, potentially reinforcing redistribution of flow paths to other wetland areas. In both cases, crossing a system threshold might lead to degradation in which the return to a functional system is unlikely. The ex les presented highlight the need to incorporate a co-evolutionary framework for the analysis of changing connectivity patterns and the emergence of thresholds in arid and semi-arid systems. This framework can be used for the identification of early warning indicators of transitions from healthy to degraded states, which are useful for management applications.& &
Publisher: MDPI AG
Date: 20-07-2023
DOI: 10.3390/RS15143615
Abstract: Precipitation is a critical driver of vegetation productivity and dynamics in dryland environments, especially in areas with intense livestock farming. Availability and access to accurate, reliable, and timely rainfall data are essential for natural resources management, environmental monitoring, and informing hydrological rainfall-runoff models. Gauged precipitation data in drylands are often scarce, fragmented, and with low spatial resolution therefore, satellite-estimated precipitation becomes a valuable dataset for overcoming this constraint. Using statistical indices, we compared satellite-derived precipitation data from four products (CHIRPS, GPM, TRMM, and PERSIANN-CDR) against gauged data at different temporal scales (daily, monthly, and yearly). Spatial correlations were calculated for GPM and CHIRPS estimates against interpolated gauged precipitation. We then estimated NDVI response to Antecedent Accumulated Precipitation (AAP) for 1, 3, 6, 9, and 12 months of four major vegetation types typical of the region. Statistical metrics varied with temporal scales being highest and acceptable for periods of 1 month or 1 year. At monthly scale GPM presented the best Pearson’s Correlation Coefficient (r), Root Mean Square Error (RMSE) and RMSE-observations standard deviation ratio (RSR) and CHIRPS resulted in lower Mean Error (ME) and Bias. On an annual basis CHIRPS showed the best adjustment for all indicators except for r. NDVI responses to 3 months of AAP were significant for all vegetation types in the study area. The findings of this study show that estimated precipitation data from GPM and CHIRPS satellites are accurate and valuable as a tool for analysing the relationships between precipitation and vegetation in the drylands of Mendoza.
Publisher: Springer Science and Business Media LLC
Date: 13-07-2017
DOI: 10.1038/NCOMMS16094
Abstract: The future of coastal wetlands and their ecological value depend on their capacity to adapt to the interacting effects of human impacts and sea-level rise. Even though extensive wetland loss due to submergence is a possible scenario, its magnitude is highly uncertain due to limited understanding of hydrodynamic and bio-geomorphic interactions over time. In particular, the effect of man-made drainage modifications on hydrodynamic attenuation and consequent wetland evolution is poorly understood. Predictions are further complicated by the presence of a number of vegetation types that change over time and also contribute to flow attenuation. Here, we show that flow attenuation affects wetland vegetation by modifying its wetting-drying regime and inundation depth, increasing its vulnerability to sea-level rise. Our simulations for an Australian subtropical wetland predict much faster wetland loss than commonly used models that do not consider flow attenuation.
Publisher: Elsevier BV
Date: 04-2018
No related grants have been discovered for Steven Sandi.