Floodplain Vegetation Research Articles

Influence of Vegetation in The Flood Drainage Ditch

Flood drainage ditches serve as critical infrastructure, directing and managing floodwaters to prevent indiscriminate flow, reduce flooding risks, and curb erosion. Vegetation plays a crucial role in enhancing the effectiveness of these ditches. It acts as a natural barrier, mitigating floodwater speed and impact while stabilizing soil and preventing erosion. Furthermore, vegetation aids in water quality improvement by filtering pollutants and nutrients, making it safer for humans, animals, and plants. It also reduces peak flows and attenuates floodwaters, thereby minimizing urban flooding risks. Additionally, the presence of vegetation in floodplains provides extra storage capacity for excess water, supporting floodplain management and biodiversity conservation. The study emphasizes the importance of carefully considering vegetation type, characteristics, and management practices to optimize flood drainage ditch performance. Selection of suitable plant species and morphological optimization significantly enhances drainage capacity and infiltration rates. Proper maintenance and management practices are vital to ensure unimpeded water flow and prevent obstruction.

Mapping Fractional Vegetation Cover Using Unoccupied Aerial Vehicle Imagery to Guide Conservation of a Rare Riparian Shrub Ecosystem in Southern California

The use of unoccupied aerial vehicles (UAVs) for vegetation monitoring is widespread in agriculture and forestry but far less so in ecological restoration where it has tremendous unrealized potential. We tested the ability of multispectral data and a derived vegetation index to classify shrub, herbaceous vegetation, and bare soil cover in a rare alluvial floodplain vegetation community in semiarid Southern California, where shrub cover is manipulated in restoration efforts aimed to provide open habitats required by several threatened and endangered species. Three classifiers and three levels of spatial aggregation were compared for their ability to provide accurate shrub cover estimates at a scale commensurate with the needs of conservation managers. We used object-based image analysis (OBIA) and compared maximum likelihood (ML), support vector machine (SVM), and random forest (RF) classifiers applied to high-spatial resolution (0.14 m) data from a four-band Parrot Sequoia+ multispectral sensor. The SVM and RF classifiers yielded similarly high classification accuracy evaluated using the training data (overall accuracy of 96.4% and 97.6%, respectively), much higher than ML (88%). Aggregating shrub cover data to 25 and 50 m resolutions yielded more accurate and well-calibrated cover estimates (mean absolute error 12% and 11%, respectively, for RF) than 10 m aggregation (MAE 19% for RF). Shrub cover estimated using RF and SVM was able to meet the restoration monitoring needs to distinguish the three phases of shrub habitat characterized by their cover (10–30%, 30–75%, >75%) that differ in habitat quality and restoration prescriptions.

Флористическое разнообразие поймы Нижней Оби в Ямало-Ненецком автономном округе

Information on the flora of the Lower Ob River floodplain being about 500 km long within the Yamalo-Nenets Autonomous Okrug (YNAO) has been summarized for the first time. The taxonomic diversity of the floodplain flora is considered in the latitudinal aspect. The total number of taxa is 322 including 301 species, 18 subspecies and three species variations. The taxa belong to 155 genera and 56 families. They are given in the alphabetical order. The floristic richness of floodplain vegetation changes and the Sørensen coefficient between floras of the study areas decreases from south to north are shown. 21 % of taxa are found throughout the whole floodplain territory. The proportions of the identified flora are considered in comparison with the floodplain flora of the Middle and Upper Ob. The authors have found new habitats of four taxa listed in the Red Data Book of the YNAO (2010), four from Appendix 1 of the Red Data Book and 29 taxa being rare for the territory of the Okrug, including two listed for the Okrug for the first time.

The impact of flood regime on river floodplain vegetation coverage: Insights from a 30-year Landsat record

The impact of flood regimes on river floodplain vegetation within banks remains poorly understood. In this study, we examined the monthly variation of river floodplain vegetation coverage (RFVC) at a typical reach of the Yangtze River with a 30-year Landsat record. We evaluated its relationships with 13 hydrodynamic characteristic indices. Our results showed that the flow regime alteration associated with dam construction led to an increase in the downstream RFVC every month throughout the year. The maximum specific energy, reflecting both physical and physiological damage effects to riparian plants, was most negatively related to the RFVC after floods (i.e., from September to October) in the whole 30-year period (Adj.R2 = 0.64, p < 0.05). The flood duration with water levels above floodplain vegetation had the most significant negative correlation with RFVC in the post-dam period (Adj.R2 = 0.84, p < 0.05). Also, the change of riparian vegetation area in different elevation zones before and after floods mainly depended on the combined effect of vegetation distribution and flood intensity. Our findings give insights into river floodplain vegetation dynamics and provide scientific support to riparian vegetation modelling.

Visual evaluation of soil structure in low‐intensity land use systems of steppe zone of Ukraine

AbstractThe network of natural forests and shelterbelts is a crucial element of agroforestry systems for the efficient and environmentally sustainable land use in Ukraine. From 2016 to 2021, we studied the quality of black soils structure under steppe wildland herbaceous vegetation, man‐made tree plantations of Robinia pseudoacacia L. and Quercus robur L., and native forest vegetation of ravines and floodplains in the steppe zone of Ukraine. According to the visual evaluation of soil structure (VESS) scores, the content of the agronomically valuable fraction (AVF), soil organic carbon (SOC) and earthworm casts, native forest soils (Chernozems and Phaeozems) had a significantly (p &lt; .05) higher soil structural quality in 0–25 cm layer as compared with the Chernozems under the steppe vegetation and shelterbelt plantations. In the conditions of steppe landscapes, VESS methods were shown to provide efficient diagnostics to differentiate the black soil structural quality of low‐intensity land use systems, that is steppe wildlands, shelterbelts, native forests: VESS indicators significantly (p &lt; .05) correlated with quantitative characteristics of soil structure. The most significant dependence was found between VESS parameters and earthworm casts content. The need to improve VESS method was demonstrated, that is to assign higher weight to the earthworm bioturbation process as one of the key indicators of soil structural quality.

The heterogeneous geomorphological impact of an exceptional flood event and the role of floodplain vegetation

AbstractApplication of an integrated spatial approach combining several sources of remote sensing data to include both channel and floodplain morphological and sedimentological impacts has identified the geomorphological effects of three extreme flood events during a single flood season (2019–2020) along a 16‐km reach of the River Teme, UK. This combined approach allowed the assessment of in‐channel pattern development, incision and aggradation; lateral bank migration; and overbank sedimentation and scour by out‐of‐channel flows. Rates of change during the event period were compared with those in the previous 10 years. The approach also allowed the role of vegetation and cultivation, both bankside and out on floodplains, to be assessed with variations in the extent of riparian wood and channel slope driving contrasts in the extent of the response. The spatial impacts from such extreme events are highly localised, varied in kind, and can be considered for both rivers and floodplains together. Erosional effects were distinctively distributed and not simply contributions to ongoing meander development; channel aggradation was localised, and overbank sedimentation explicably patchy. In reaches without woody vegetation, differences in channel and floodplain slope, local floodplain relief as created by prior events, and the impact of man‐made structures were factors that drove variations in flood response. This study strongly underlines the role of continuous riparian vegetation in maintaining bank stability and constraining lateral channel migration, but also to the potential influence of floodplain vegetation and planting for ‘natural engineering’ in the context of floodplains as well as channels in comparable environments. Maintenance of riparian vegetation in the context of landowner and Natural England conflict and management of future flood risk is important, but also highlighted is the need to consider the role of hedgerows and wider planting for constraining soil and riverbank erosion during flood events.

Changes in the Occurrence of Five Invasive Plant Species in Different Ecosystem Types between 2009–2018 in Hungary

Modelling and analysis of spatiotemporal characteristics of plant invasion can help in mapping and predicting the spread of invasive plants. The aim of our research was to investigate the spatiotemporal variability of five common invasive plant species (Ailanthus altissima, Asclepias syriaca, Elaeagnus angustifolia, Robinia pseudoacacia, and Solidago spp.) within different land cover (ecosystem)-type categories. The basis of the study was the National Geospatial Database of Invasive Plants (NGDIP) of Hungary, and the ecosystem types of the Ecosystem Map of Hungary (EMH). The GIS-based analysis of the detailed occurrence database of the invasive species (NGDIP) and the thematic land-cover (ecosystem)-type maps (EMH) examined allow us to answer the question of in which habitat types the occurrence and distribution of the given invasive plant has stagnated, decreased, or increased between 2006 and 2018. We developed a methodology with relevant data sources and demonstrated invasion variation, which can be used for future management planning and invasive biology research. Our results show that Asclepias syriaca and Robinia pseudoacacia are increasingly threatening grasslands and are also spreading more intensively in complex cultivated areas. The occurrences of Ailanthus altissima and Asclepias syriaca are declining in built-up areas due to the increasingly extreme environmental conditions of cities or modified urban planning. The spread of Solidago spp. is increasingly common in wetlands, threatening the biodiversity of floodplain (riparian) vegetation.

Experimental Observations of Floodplain Vegetation, Bedforms, and Sediment Transport Interactions in a Meandering Channel

AbstractFloodplains provide important ecological, hydrological, and geomorphic functions within river corridors. During overbank flows, complex hydrodynamic conditions occur as water exits and re‐enters the channel and interacts with hydraulically rough floodplain vegetation. However, the extent to which floodplain vegetation influences channel‐altering hydrodynamic forces and thus bedform topography and sediment transport is poorly understood. We address this knowledge gap and present the results of flume experiments where we measured bedform topography under varied floodplain vegetation conditions at two overbank flow relative depths. The experiments were conducted in a 1‐m wide meandering compound channel inset in a 15.4 long, 4.9‐m wide basin. The channel bed was a mobile sand‐and‐gravel mixture with a median sediment size of 3.3 mm, and sediment transport occurred only within the channel. We tested bare and vegetated floodplain conditions with 2.7‐cm diameter rigid emergent vegetation elements at spacings of 3.0 and 12.1 units m−2. We performed a moving‐window analysis of topographic surface metrics including skewness, coefficient of variation, and standard deviation, as well as topographic patch analysis of area and contagion to measure changes in bedform heterogeneity as flow depth and vegetation density were varied. Our results show that both greater density vegetation and larger flows can increase bedform topographic heterogeneity. These findings suggest that floodplain vegetation and natural hydrologic regimes that include overbank flows can enhance stream habitat complexity. Designing for the effects of established vegetation conditions and prioritizing floodplain vegetation planting may be useful for river managers striving to achieve successful biomic river restoration.

Development of a computationally efficient floodplain ecological response model for large-scale, data-sparse riparian environments

Quantitative assessment of floodplain ecological response to flow regimes is challenging but essential for setting targets and estimating impacts for environmental water management. This paper proposes a model that takes long-term (90 years) and large-scale (9 million grid cells) flood maps as input to estimate the response of floodplain vegetation using infinitely differentiable functions. The model, named Floodplain Ecological Response Model (FERM), is calibrated against 1-D temporal Leaf Area Index (LAI) data from the WAVES energy and water balance model at a daily timestep, and validated on the entire floodplain using condition data of the Icon Sites of the Murray River aggregated to a yearly timestep. Results show that FERM can adequately simulate the response of different types of vegetation on the floodplain, while reducing the data requirements and runtime drastically compared to other approaches. The FERM modeling approach is a first step towards a quantitative modeling of floodplain forest ecosystems at large scale with realistic data and computation requirements. It is intended to indicate the potential of such an approach in semi-arid systems where data availability is limited, and to encourage the further research needed to improve our understanding of floodplain forests and our capacity to model the impact of floods on their ecological response.

Research and Application of the Calculation Method of River Roughness Coefficient with Vegetation

The roughness coefficient is a comprehensive parameter reflecting river resistance, which is widely used in the planning and design of river regulation and flood control projects. In recent years, as the upstream water conservancy and hydro-power projects have been put into operation, the frequency of low flow in the middle and lower reaches has increased, and the frequency of flood flow has decreased. All kinds of vegetation in the river floodplain grow luxuriantly, which causes a change in the river resistance and roughness coefficient. The present study was carried out with theoretical analysis and laboratory tests. A formula for the roughness coefficient calculation was derived based on the momentum equilibrium equation and momentum exchange between the vegetation layer and upper layer. The relationship between the depth-averaged velocity within the vegetation layer and depth-averaged velocity of the whole flow was analyzed. The reliability of the formula was verified by a large amount of previous experimental data. Based on the derived formula, the variation law of the roughness coefficient with vegetation density, vegetation height, and water depth were obtained. For the emerged vegetation flow, the Manning coefficient tended to increase with the increase in the vegetation density and water depth. For the submerged vegetation flow, the Manning coefficient showed a trend of decreasing with the increase in the water depth and increased with the increase in the vegetation height. Finally, the derived formula was applied in the Yueyang reach of the Yangtze River and the Duliujian River. The study can be applied in the fields of water level-flow discharge relationship analysis and the water surface line calculation of vegetated rivers.

Downstream changes in floodplain sedimentation and their effects on channel avulsion in stream-dominated alluvial fans: The Cretaceous Duwon Formation in the southern Korean Peninsula

Stream-dominated alluvial fans are formed by the periodic channel avulsion running on their surfaces and are characterized by the downstream changes in hydrodynamics of stream flows and flood frequency. The spatial variations in hydrodynamics also control the sedimentation on the floodplain, which is important for sediment dispersal patterns on the stream-dominated alluvial fans as they feed back into channel avulsion processes. To understand the influence of downstream changes in hydrodynamics on the floodplain sedimentation and associated channel avulsion processes, we studied the Cretaceous Duwon Formation in the southern part of the Korean Peninsula. The Duwon Formation unconformably overlies the Paleoproterozoic basements and consists of gravelly braided stream deposits (FA-1), sandy braided stream deposits (FA-2), and calcretes-bearing floodplain deposits (FA-3). Close to the basements, FA-1 shows the radial paleoflow patterns, and the size of sediments and the ratio of channel to floodplain deposits decrease downstream over a relatively short distance (<7 km). This indicates that the Duwon Formation was deposited in the stream-dominated alluvial fans under arid to semi-arid climatic conditions, which can be classified into the proximal, medial, and distal zones.In the medial zone, the floodplain deposits are composed of the underlying, purple-colored sandstones and the overlying, compensational stacked crevasse channel and splay deposits (ca. 19 m thick) with the unsystematic paleoflow directions, finally overlain by the sandy braided stream deposits. In contrast, in the distal zone, the floodplain fines are composed of homogeneous clay and silt with calcretes and vegetation traces. These floodplain fines are interbedded with and overlain by the progradational stacked, coarsening- and thickening-upward trending, crevasse channel and splay deposits (ca. 18 m thick) with the constant paleoflow directions to those of the overlying sandy braided stream deposits. In the medial zone, a relatively large volume of discharge of the stream floods resulted in the frequent overbank flooding via the multiple breaching points and the concomitant growth of alluvial ridges by the combined effects of in-channel bed aggradation and compensational stacked crevasse channel and splay deposits resulted in a shift in the flow pathway of the sandy braided streams. In the distal zone, the floodplain fines containing calcretes and vegetation traces suggest the longer periods of non-deposition, providing sufficient time for the vegetation development. Once the channel levees collapsed, the vegetated channel levees stabilized the breaching point, and the breaching point progressively incised by the multiple flooding events, causing susceptibility to overbank flooding. Crevasse channel flows via the breaching point and associated overbank floodwaters led to a continuous supply of the coarse-grained sediments stacking on the cohesive, vegetated floodplain fines, with an increase in the cross-floodplain topographic gradient. As a result, crevasse channels were able to advance the distal floodplains, resulting in the development of progradational stacking pattern. With the cross-floodplain topographic gradient, the deposition of these erodible overbank flooding sediments on the cohesive, vegetated floodplain fines provided an alternative route for the parent channel, resulting in channel avulsion. Thus, this study suggests that downstream changes in hydrodynamics and associated floodplain sedimentation are important for channel avulsion and hence control the sediment dispersal patterns of coarse-grained sediments on the stream-dominated alluvial fans.

Investigation approaching flow to bridge and prediction of bridge pier scour with floodplain vegetation in compound channels under pressurized flow conditions

The local scouring around the pier, is one of major cause of the bridges failure worldwide. Compared to the flow hydraulics in single channels, the flow pattern in compound channels is completely different with flood plains covered with vegetation and this issue can affect the amount of scouring in the area of bridge piers. However, the combined effect of these factors has not been systematically investigated. Therefore, due to the complex nature of the local scouring phenomenon and the absence one of an accurate prediction model, in this research, an experimental study on the hydraulic characteristics of the flow approaching the bridge deck in compound channels with floodplain vegetation in pressurized flow conditions, has been done. It was found that increasing vegetation density on average will reduce scour depth by 15% for the same floodplain width and relative depth. In free-flow conditions, increasing the vegetation density on average will increase the scour depth. The aim is to develop an optimized model to estimate the bridge pier scour in consideration of the combined effect. The newly developed relationship shows a good correlation coefficient of more than 92% with the experimental data and yielded better results than the previous equations. The finding of this study will have potential applications for the prediction of the bridge pier scour in clear water conditions.

Nutrients in tropical and temperate rivers and floodplains – comparison of the Rivers Songkhram (Thailand) and Narew (Poland)

Ecological processes in floodplains may function differently across climate regions. We compared the river discharge, water chemistry, and nutrient budget and balance of floodplain vegetation in a temperate climate (River Narew, Poland) with those in a tropical climate (River Songkhram, Thailand). Both rivers show a discharge regime with a flood pulse, following snowmelt (Narew) or monsoon rainfall (Songkhram), with peak discharges roughly 25 times higher in the River Songkhram. Electrical Conductivity (EC) values of both rivers are generally comparable, while nutrient concentrations are somewhat higher in the temperate River Narew (with total phosphorus (TP) approximately 1.5 and total inorganic nitrogen (TIN) approximately 2.2 times higher than in Songkhram). A comparison of the nutrient budget of floodplain vegetation suggests that soil is the most important source of nutrients for most vegetation types, i.e., Narew sedge (N), Narew forest floor (N and P), Songkhram bamboo (N and P), and Songkhram grass (P). Additionally, floodwater is the main input source of P for the Narew sedge and a secondary input source for Songkhram grass. Vegetation close to the river tends to have higher productivity, emphasizing the nutrient-filtering function of floodplain vegetation. For both rivers, nutrient input into the floodplains by floodwater is higher than nutrient export from the floodplains, indicating that both floodplains have a nutrient sink function. These findings demonstrate that the floodwater pulse is a source of nutrient input for floodplain vegetation in both temperate and tropical climates, with the soil playing a vital role in the nutrient budgets and balance.

Soils and vegetation of the riverside floodplain in the hydrological continuum of the southern tundra within the Pur–Taz interfluve (Western Siberia)

Soils and vegetation of the riverside floodplain in the hydrological continuum of the southern tundra within the Pur–Taz interfluve (Western Siberia)

Environmental drivers of spatio-temporal dynamics in floodplain vegetation: grasslands as habitat for megafauna in Bardia National Park (Nepal)

Abstract. Disturbance-dependent grasslands, often associated with hydromorphological and fire dynamics, are threatened, especially in subtropical climates. In the Nepalese and Indian Terai Arc Landscape at the foot of the Himalayas, natural and cultural grasslands serve a viable role for greater one-horned rhinoceros (Rhinoceros unicornis) and for grazers that form prey of the Royal Bengal tiger (Panthera tigris). The grasslands are vulnerable to encroachment of forest. We aimed to establish the effects of environmental drivers, in particular river discharge, river channel dynamics, precipitation and forest fires, on the spatio-temporal dynamics of these grasslands. The study area is the floodplain of the eastern branch of the Karnali River and adjacent western part of Bardia National Park. We created annual time series (1993–2019) of land cover with the use of field data, remotely sensed LANDSAT imagery and a supervised classification model. Additionally, we analysed the pattern of grassland patches and aerial photographs of 1964. Between 1964 and 2019, grassland patches decreased in abundance and size due to encroachment of forest. Outside the floodplain, conversion of grassland to bare substrate coincides with extreme precipitation events. Within the floodplain, conversion of grassland to bare substrate correlates with the magnitude of the annual peak discharge of the bifurcated Karnali River. Since 2009, however, this correlation is absent due to a shift of the main discharge channel to the western branch of the Karnali River. Consequently, alluvial tall grasslands (Saccharum spontaneum dominant) have vastly expanded between 2009 and 2019. Because the hydromorphological processes in the floodplain have become more static, other sources of disturbances – local flooding of ephemeral streams, anthropogenic maintenance, grazing and fires – are more paramount to prevent encroachment of grasslands. Altogether, our findings underscore that a change in the environmental drivers impact the surface area and heterogeneity of grassland patches in the landscape, which can lead to cascading effects for the grassland-dependent megafauna.

Flow in multi-layered vegetated compound channels with different bank slopes

Bank angle and floodplain vegetation emergence determine the flow nature in a compound channel. Two sets of 45° and 90° bank angle compound channel is considered in the present work. Each set considers three cases of vegetation arrangements: no vegetation, multi-layered fully submerged, and multi-layered partially emergent. The flow characteristics like velocity, Reynolds shear stress (RSS), and turbulent kinetic energy (TKE) do not vary much in the cross section in the absence of vegetation. However, with vegetation, the slopes and nearby region are affected the most as it acts as an intermediary region between the main channel and floodplain. An analysis of the anisotropic invariant map shows the dominance of the transverse component in the slopes compared to the main channel and floodplain. The velocity in and around the slopes is higher for steep slopes (90°) compared to a gradual slope (45°) compound channel. The streamwise RSS and bursting events also show higher magnitude near the channel bed in and around the sloping region. This indicates the instability of the steep banks compared to gradual bank slopes. The increase in floodplain vegetation emergence also affects the slopes. The magnitude of RSS and TKE in the slopes is higher with greater vegetation emergence in the floodplain. This shows the higher vulnerability of the slopes in the presence of higher vegetation emergence. From the hydraulic engineering perspective, this study will be helpful in the field of understanding the failure of banks and ways to maintain their stability.

An analytical model for transverse velocity distributions of overbank flows with submerged and emergent vegetated floodplains

AbstractThe emergence of floodplain vegetation enhances the local drag and affects the velocity distribution of the overbank flow in a two‐stage channel. Numerous analytical models (e.g., the modified SKM models) have been established to simulate the transverse velocity distributions of overbank flows with vegetation. However, the dimensionless eddy viscosity (λ) was simplified to be a constant in these models when quantifying transverse momentum exchange. In this paper, we develop a novel analytical model to simulate the depth average velocity profiles of overbank flows with floodplain vegetation. Considering a micro‐hexahedral element on a vegetated‐bed area for a two‐stage rectangular channel, the governing equation of the vegetated overbank flow is derived. An improved eddy viscosity model that considers the transverse variation of the λ is employed to quantify the transverse momentum transfer, and a linear empirical function simplifies the secondary current. The simulated depth average velocities agreed well with the published measurements. In comparison with existing models, the proposed model shows better prediction accuracy, particularly in the shearing layer domain. More importantly, for the optimized model parameters, we found that the dimensionless eddy viscosity plays the most influential role when simulating depth‐averaged velocities in the shearing layer domain, whereas the drag force dominates for vegetated floodplains. This study provides a convenient method for predicting the flow velocity in overbank floods with vegetation.

Debris flow characteristics of the compound channels with vegetated floodplains

Compound cross-sections with vegetated floodplains are a common type of cross-section in debris-flow gullies. Floodplain vegetation participates in large-scale debris flow events and regulates debris-flow discharge. Extensive research has been conducted on the water flow characteristics of compound rivers. However, few studies have investigated the debris flow characteristics of compound channels in mountainous areas, particularly those of debris flow and flash flood inundation areas with vegetation. This study discusses the section characteristics of debris flow gullies with vegetated floodplains, gully evolution processes, and their influence on debris flow. The results show that the compound debris flow gully with a vegetated floodplain is formed in the gully from the mature stage to the old-mature stage. The compound sections are developed in flow areas with a gentle slope, which can be bilateral floodplain, unilateral floodplain, and multi-main gully floodplain types. Owing to the vegetation of the floodplain, the roughness of the channel increases, which makes the beach roughness coefficient much larger than that for the main channel. In the integrated Manning coefficient method, the error in resolving the flow velocity and discharge is large and cannot reflect the difference in velocities of the floodplain and main channel, therefore the sectional splitting method is most applicable. Influencing debris flow movement, limiting channel migration, and retaining debris flow to the main channel were the main contributions of the riparian forest zone.

Крупные хищные птицы в заповеднике «Нургуш», Кировская область, Россия

Крупные хищные птицы в заповеднике «Нургуш», Кировская область, Россия

Finding Ngabi (Hemiaspis damelii): factors affecting the use of modified floodplain wetlands by an endangered snake

Context River regulation, coupled with climate change, has caused significant declines in global freshwater biodiversity. In Australia, water extraction within the Murray–Darling Basin (MDB) has reduced the frequency, extent and duration with which floodplains are inundated, resulting in widespread declines in wetland-dependent biodiversity, including reptiles. The endangered Ngabi (Hemiaspis damelii) is associated with floodplain systems in the MDB, yet its distribution and ecological requirements are poorly understood, hampering conservation actions. Aims We sought to validate an assumption that Ngabi is associated with wetland vegetation communities before investigating factors affecting its probability of detection in the lower Murrumbidgee catchment in southern New South Wales. We predicted Ngabi occurrence patterns would relate to frog abundance, wetland hydrology, microhabitat attributes and meteorological variables. Methods We compared Ngabi observations from 16 paired wetland and dryland vegetation transects to evaluate associations with vegetation type. We then used generalised linear mixed models to relate snake presence and absence to prey (frog abundance), microhabitat (logs and ground cover), wetland hydrology (water depth and inundation frequency) and meteorological conditions, using 12 repeat surveys between September 2018 and March 2021. Key results Fifty-eight snakes were observed at five of eight wetlands during the study. Ngabi was exclusively recorded in river red gum/spike rush or lignum vegetation communities, and was absent from sandhill woodland or chenopod communities. The probability of detecting Ngabi increased with ambient temperature and weakly with wetland inundation frequency, but not frog abundance, microhabitat attributes or year. Conclusions Ngabi is strongly associated with floodplain vegetation communities and, to some extent, frequently inundated wetlands in southern NSW, suggesting water management agencies should incorporate threatened floodplain snake species into future wetland management plans. The use of environmental water to restore aspects of flow regimes, improve wetland health and aquatic diversity is likely to benefit other wetland-dependent snake populations across the MDB. Implications The positive relationship between Ngabi detections and ambient temperature will be important for designing an effective monitoring program for the species across the MDB. Furthermore, our findings provide insight into the benefits of using environmental water to create wetland refuges to maintain floodplain snake populations during droughts.