Water Level Variations Research Articles

Development and validation of an AI-Driven model for the La Rance tidal barrage: A generalisable case study

In this work, an AI-Driven (autonomous) model representation of the La Rance tidal barrage was developed using novel parametrisation and Deep Reinforcement Learning (DRL) techniques. Our model results were validated with experimental measurements, yielding the first Tidal Range Structure (TRS) model validated against a constructed tidal barrage and made available to academics. In order to proper model La Rance, parametrisation methodologies were developed for simulating (i) turbines (in pumping and power generation modes), (ii) transition ramp functions (for opening and closing hydraulic structures) and (iii) equivalent lagoon wetted area. Furthermore, an updated DRL method was implemented for optimising the operation of the hydraulic structures that compose La Rance. The achieved objective of this work was to verify the capabilities of an AI-Driven TRS model to appropriately predict (i) turbine power and (ii) lagoon water level variations. In addition, the observed operational strategy and yearly energy output of our AI-Driven model appeared to be comparable with those reported for the La Rance tidal barrage. The outcomes of this work (developed methodologies and DRL implementations) are generalisable and can be applied to other TRS projects. Furthermore, this work provided insights which allow for more realistic simulation of TRS operation, enabled through our AI-Driven model.

Variability of the coastal currents, waves and wind surge along the shore of the South-Eastern Baltic (Kaliningrad Oblast, Russian Federation)

The coastline of the Kaliningrad Oblast is an area of the South-East Baltic, which continues from the Vistula Spit to the Curonian Spit via Sambia Peninsula. The coastline has been subject to severe erosion over the past years. The goal of the paper is to analyse whether the alongshore variations of the storm surge water level, field of waves and currents are the reason for the erosion alongshore variability. The numerical simulations were carried out using the quasi-stationary approach for the model wind. The offshore wave breaking distance and the non-linear dependence between wind surge and wind speed were estimated for four typical coastline sites. The alongshore velocity on most of the coastline was enough powerful to transport the fine, medium and coarse sands. West, northern-west and north winds were defined as the most dangerous for coastal erosion. The convergence and divergence of alongshore currents as well as the vortex zones were identified for each wind direction. The results were used to analyse the alongshore current velocity, wind surge, and significant wave height variability against the shore erosion characteristics. The hypothesis that the places of convergence and divergence of alongshore currents correspond to the accumulative and erosion zones was not confirmed with one exception on the western shore of the Sambia Peninsula. Three options were supposed to explain the absence of correlation between the monitoring results on coastal erosion and modelled hydrodynamic conditions: the studied shore has not had enough free sand to demonstrate the typical behaviour of dissipative shores; the erosion characteristics depend on the very local conditions which were not resolved by numerical model; the main erosion has happened at the short term event basis when waves reach the shore at the background of a general Baltic Sea high-water level and is not a result of the general alongshore distribution of waves, wave surge and current characteristics.

The effect of variations in water level on wave overtopping discharge over a dike: An experimental model study

The water level during a storm event is never constant but variable in nature. A variable water level leads to varying crest freeboards at the coastal defense structure. A change in crest freeboards is directly linked to a changing average overtopping discharge q over the coastal defense structure. The existing prediction formulae for q are developed for constant water level ( C W L ) and do not take into account its variability ( V W L — variable water level) during a storm event. Hence, in this study the influence of the V W L on q was investigated experimentally. Model tests were conducted in the wave flume facility at Ghent University, where a range of V W L was modelled as representative for typical storm surges (total variation of the water level d h = 0.75–4.8 m) and a range of storm durations (time t = 2.7–22 h). During testing the q for these cases of V W L over a reference impermeable sloping (seaward slope of the structure cot( α ) = 2) dike structure was measured. Initial validation of model results for the C W L situation showed that the model setup was capable of reproducing the predicted q values from Eurotop (2018). For the V W L situation it was noted that the existing prediction formulae (Eurotop, 2018) are overestimating the measured q value, especially for smaller relative crest freeboards (relative freeboards R c / H m 0 < 1 . 5 ) when the smallest freeboard is considered. By using linear regression a new equivalent relative crest freeboard was derived to reduce the difference between q predicted by existing EurOtop (2018) and q measured during variable tests. The new equivalent freeboard is mainly dependant on the relative crest freeboard during the peak of the storm ( R c p e a k / H m 0 ), as well as the total storm surge variation ( d h). The existing formulation from EurOtop (2018) was kept by replacing R c by this new equivalent crest freeboard. The adapted formula for q is able to accurately predict the overtopping discharge for both, C W L and V W L situation. • 2D Physical model tests on wave overtopping performance of a smooth dike. • Influence of variable water level conditions on the average wave overtopping discharge. • New equivalent relative freeboard is determined to include this effect in the EurOtop formula for non-breaking waves. • Predictions are significantly improved with the new equivalent relative freeboard for the new data.

Challenges and opportunities for a South America Waterway System

South America has been developed from its coast to its hinterlands since the beginning of its Western colonization. However, to this point, no significant effort has been made to integrate its interior. Waterways transportation can be considered the most sustainable inland mode of transportation due to its low CO 2 emissions per ton of cargo transport. With this in mind, this paper investigates the history, challenges and opportunities of the past proposals for the construction of the South America Waterway System (SAWS) connecting the La Plata, Amazon, and Orinoco river basins. It focuses on particular challenges of the proposed waterway. (i) a comparison between the deforestation surrounding existing road and waterway infrastructure in the Amazon, (ii) the large water level variation in the Amazon basin, (iii) and the alternatives for storing water to reduce the impacts of floods and droughts in the proposed waterway. We conclude that deforestation surrounding existing waterways is practically zero and that groundwater storage has an important role in storing water for the basin and reservoirs, a limited one. The SAWS can significantly foster South American integration, encourage sustainable extraction of natural resources in the region and help the conservation of the Amazon forest.

Effects of water level variations on survival, morphological phenotype and responsiveness of tadpoles to phytohemagglutinin

To investigate the responses of morphological and physiological characteristics in tadpoles of Pelophylax nigromaculatus to various water levels, a total of 480 tadpoles with similar sizes were treated with rapid, moderate and slow desiccation. Both the metamorphosis duration and average metamorphosis survival rate of specific developmental stages were counted. Their body and internal organ sizes, as well as the responsiveness to phytohemagglutinin (PHA-P) of froglets were measured after complete metamorphosis. The results showed that the metamorphosis duration of tadpoles in the control group was the longest. The average metamorphosis survival rate of different treatment groups ranged from 72.5% to 90.8%, which was the highest in the control group and the lowest in the rapid desiccation group. Body weight (BW) and body length (BL) of froglets in control and slow desiccation groups were significantly higher than those of moderate or rapid desiccation groups. Body width, ratio of BW to BL, carcass wet weight and the wet weight index of lung and fat body were the lowest in rapid desiccation group. There was no significant difference in the wet weight index of heart, spleen, kidneys and digestive organs, as well as the length index of different segments of whole digestive tract between groups. The maximal response value of froglets to PHA-P appeared at 3 h after injection in different treatments, which was significantly higher in moderate and slow desiccation groups than the control group. There was no significant difference between rapid desiccation group and any other groups. The tadpoles of P. nigromaculatus might accelerate the metamorphosis developmental process to cope with desiccation stress, accompanying with decreased atrophic body size and weakened cell-mediated immunity, which would harm tadpoles to successfully land.

Impact of Drought on the Life Cycle of Barge Transport

This paper aims to analyze the impact of drought on the life cycle of barge transportation. The LCA method was used to quantify the environmental impact of barge transportation services on the Madeira River/Brazil: Transportation Operation, Barge Fleet, and Waterway Infrastructure. A model for barge convoy formation was developed as a function of river water level variation. From this, the transport operation was simulated, considering the loading of grains from the Madeira River in 2021, as well as the respective fuel consumption and CO2Eq emissions. The results indicate that barge transportation is more harmful to the environment during drought, since only a convoy of nine barges is allowed to navigate, and its energy efficiency is compromised due to the longer travel time and lower loading capacity in one trip. The intense use of this barge convoy implied an increase of 22.25% in CO2Eqemissions when compared to the full river. Doi: 10.28991/CEJ-2022-08-12-02 Full Text: PDF

Assessment of total evaporation rates and its surface distribution by tridimensional modelling and remote sensing

In arid and semiarid environments, evaporation is responsible for significant water losses from reservoirs. This condition is of special concern in the Brazilian Northeast region, as this is one of the most populous semiarid areas in the planet. The present study aims to assess the spatio-temporal variability of evaporation rates on the water surface of Pentecoste reservoir, located in the Brazilian semiarid region, by using both the hydrodynamic model Delft3D and a remote sensing technique (RS). While RS has already been used to evaluate the spatial distribution of evaporation rates in lakes, Delft3D was innovatively tested and applied for this purpose for the first time in this study. The calibration results showed an accurate reproduction of the water level variability (r2 of 0.997), along with a satisfactory calibration of the reservoir's thermal structure for the full water column (MAE of 0.539 °C, RMSE of 0.572 °C, and NMAE of 0.008). Curves relating monthly evaporation rates with air temperature and wind speed showed strong correlation between those variables (r2 of 0.817 for air temperature and 0.849 for wind speed). Also, the averaged evaporation rates modeled by Delft3D differed by less than 5% compared to RS. Regarding the spatial distribution results, for the wet period the evaporation patterns were similar to those of RS, while in the dry period RS provided a more stable evaporation pattern when compared to Delft3D. The innovative approach proposed in the present study can be used to better understand the evaporation dynamics in surface waters and optimize the location of damping evaporation structures, namely air diffusers, shading systems, and floating solar panels, which are important for improving water availability, not only in drylands.

Predicting mine water inrush accidents based on water level anomalies of borehole groups using long short-term memory and isolation forest

Water level variation of explorational boreholes in mining sites is one of the most direct representations of water inrush risk. Despite recent efforts on mine water inrush accident prediction based on various types of observation data including water level of boreholes using a wide range of machine learning models, the accuracy and timeliness of the prediction for major accidents are still unsatisfactory. In this study, a novel prediction method based on the analysis of water level variation anomalies in borehole groups is proposed using the coupled model of long short-time memory (LSTM) and Isolation forest (IForest). Multi-variate LSTM algorithm is firstly used to model the correlated time sequence water level data in the borehole group, followed by the full extraction of the data variation feature based on the combination of variables including the prediction error being used as inputs of the IForest algorithm. As a result, anomalous variations of the data are detected as possible precursors of water inrush accident. Finally, a set of water inrush risk level grading rule is established based on the number of simultaneous anomalous data instances being detected within a borehole group. The results obtained for the water inrush accident in Xingdong coal mine demonstrate extraordinary timeliness and high accuracy as high water-inrush risk warning is issued for more than 2 days earlier than the time of actual sighting of the accident with very few false alarms being caused throughout the period of the testing dataset. This study provides an innovative solution to the low prediction accuracy and slow responding speed during major water inrush accidents of existing methods. The major parameters of the proposed coupled model of LSTM + IForest can also be easily calibrated based on traditional empirical methods for the best performance, allowing the method to be widely applied in various mining conditions.

Quantifying the impacts of the Three Gorges Dam on the spatial–temporal water level dynamics in the upper Yangtze River estuary

Abstract. Understanding the alterations in spatial–temporal water level dynamics caused by natural and anthropogenic changes is essential for water resources management in estuaries, as this can directly impact the estuarine morphology, sediment transport, salinity intrusion, navigation conditions, and other factors. Here, we propose a simple triple linear regression model linking the water level variation on a daily timescale to the hydrodynamics at both ends of an estuary. The model was applied to the upper Yangtze River estuary (YRE) to examine the influence of the world's largest dam, the Three Gorges Dam (TGD), on the spatial–temporal water level dynamics within the estuary. It is shown that the regression model can accurately reproduce the water level dynamics in the upper YRE, with a root mean squared error (RMSE) of 0.061–0.150 m seen at five gauging stations for both the pre- and post-TGD periods. This confirms the hypothesis that the response of water level dynamics to hydrodynamics at both ends is mostly linear in the upper YRE. The regression model calibrated during the pre-TGD period was used to reconstruct the water level dynamics that would have occurred in the absence of the TGD's freshwater regulation. Results show that the spatial–temporal alterations in water levels during the post-TGD period are mainly driven by the variation in freshwater discharge due to the regulation of the TGD, which results in increased discharge during the dry season (from December to March) and a dramatic reduction in discharge during the wet-to-dry transitional period. The presented method to quantify the separate contributions made by changes in boundary conditions and geometry to spatial–temporal water level dynamics is particularly useful for determining scientific strategies for sustainable water resources management in dam-controlled or climate-driven estuaries worldwide.

The Influence of Ecological Engineering on Waterbird Diversity in Different Habitats within the Xianghai Nature Reserve

The Xianghai National Nature Reserve of Jilin is located on the East Asian-Australian migration route of birds and plays an important role for migratory waterbirds. To explore the influence of restoration measures on migratory waterbird communities in Xianghai Reserve, we conducted a waterbird survey in the spring and autumn during waterbird migration from 2010 to 2020. The composition and spatial and temporal changes in waterbird communities were identified in the reserve and the diversity changes in waterbird communities were analyzed. The results showed that (1) the number of waterbirds increased significantly since restoration measures in 2012. Restoration measures has clearly promoted an improvement in the species and number of waterbirds. The number of waterbirds was approximately seven-times higher than that before restoration measures. (2) The number of rare waterbirds increased in the reserve, and the number of Anseriform waterbirds on the IUCN Red List of Threatened Species rapidly increased. (3) The diversity of the waterbird community has shown some recovery in the reserve, but the variation in water level during some periods led to a regular fluctuation in waterbird diversity. Restoration measures directly changed the water surface area and the water depth in the reserve, which are important variables that influence waterbird selection of wetlands as habitats. To effectively protect and manage important stopover sites on the migratory routes of waterbirds, we suggest to rationally regulate the supplementary water level of wetlands, optimize the hydrological pattern of wetlands, and strengthen the regulation of wetland water levels.

Prediction of impact of large constructions in gulf on bathymetry of its remote parts as inverse problem of wave theory

The intentional bottom changes associated with construction of dams, breakwaters and other large structures in gulfs (or harbors) often lead to unintentional delayed bottom changes at remote locations. These unintentional changes can occur due to adjustment of frequencies of natural water oscillations in gulfs (or harbors) to the frequencies of natural water oscillations in the connected seas. Affecting conditions for wave propagation, a large structure changes the natural frequencies of the gulf because these frequencies are predetermined by the gulf size and bathymetry. The sea impact will restore the old natural frequencies of the gulf, but such a restoration requires change the bottom and shoreline at various locations along the gulf. Prediction of these remote changes can be formulated as an inverse problem for shallow water equations. The key to this formulation is the orthogonality of eigen modes of water level variation and water flux in the shallow water theory. The computed predictions of bathymetry changes are compared with observed trends of changes in the Gulf of Finland.

Field observations and numerical modeling of swash motions at an engineered embayed beach under moderate to energetic conditions

Wave run-up is a key factor for the assessment of coastal flood risk during large swell events. The behavior of swash motions along embayed beaches is strongly influenced by particular features such as rocky headlands, irregular morphology, or tides, that have not received much attention in the past. In the present paper, swash motions along an engineered embayed beach were investigated under moderate to energetic wave conditions through field observations and numerical computations. Using pressure sensors and video-derived run-up data a Boussinesq-type nearshore wave model was found to capture the relevant wave transformation and swash zone processes reasonably well. The tidal water level variations were found to have a significant impact on the overall swash amplitudes and to condition the respective role of short- and long-wave components to the swash motions. In the studied configuration, the tidal level rise was shown to cause a transition from a very dissipative to a reflective or intermediate beach configuration depending on incident wave energy. Moreover, swash amplitudes were observed to vary significantly alongshore with differences of up to a factor of 2.2. Numerical results suggest that both the foreshore slope and the sub-tidal morphology play a key-role in the alongshore swash distribution.

Dam Water Level Prediction Using Vector AutoRegression, Random Forest Regression and MLP-ANN Models Based on Land-Use and Climate Factors

To predict the variability of dam water levels, parametric Multivariate Linear Regression (MLR), stochastic Vector AutoRegressive (VAR), Random Forest Regression (RFR) and Multilayer Perceptron (MLP) Artificial Neural Network (ANN) models were compared based on the influences of climate factors (rainfall and temperature), climate indices (DSLP, Aridity Index (AI), SOI and Niño 3.4) and land-use land-cover (LULC) as the predictor variables. For the case study of the Gaborone dam and the Bokaa dam in the semi-arid Botswana, from 2001 to 2019, the prediction results showed that the linear MLR is not robust for predicting the complex non-linear variabilities of the dam water levels with the predictor variables. The stochastic VAR detected the relationship between LULC and the dam water levels with R2 &gt; 0.95; however, it was unable to sufficiently capture the influence of climate factors on the dam water levels. RFR and MLP-ANN showed significant correlations between the dam water levels and the climate factors and climate indices, with a higher R2 value between 0.890 and 0.926, for the Gaborone dam, compared to 0.704–0.865 for the Bokaa dam. Using LULC for dam water predictions, RFR performed better than MLP-ANN, with higher accuracy results for the Bokaa dam. Based on the climate factors and climate indices, MLP-ANN provided the best prediction results for the dam water levels for both dams. To improve the prediction results, a VAR-ANN hybrid model was found to be more suitable for integrating LULC and the climate conditions and in predicting the variability of the linear and non-linear time-series components of the dam water levels for both dams.

Contribution of Sentinel-3A Radar Altimetry Data to the Study of the Water Level Variations in Lake Buyo (West of Côte d’Ivoire)

The artificial Lake Buyo is an important water reservoir that ensures the availability of water for multiple purposes: drinking water supply, fishing, and energy. In the last five years, this lake has experienced extreme variations in its surface area and water levels, including very significant declines, which has impacted the supply of electricity. This study aimed to assess temporal variations in the water levels of Lake Buyo using radar altimetry. Altimetric data from the Sentinel-3A satellite on Lake Buyo (tracks 16 (orbit 8) and 743 (orbit 372)) were selected over the period from 31 May 2016 to 12 June 2021 and compared to the in situ measurements provided by the Direction de la Production de l’Electricité de Côte d’Ivoire (DPE-CI). The extraction of the time series of the Sentinel-3A altimetric water levels and their corrections (geophysical and environmental corrections) were carried out with the ALTiS software. The results showed an overall agreement between the altimetric water levels and the in situ measurements, with a correlation coefficient (R2) ranging from 0.98 to 0.99 obtained, as well as a Nash–Sutcliffe Efficiency (NSE) coefficient also between 0.98 and 0.99. Further, the bias (0.12 m and 0.13 m) and root mean square error (RMSE) (0.38 and 0.67 m) values showed that the results were acceptable. The analysis of the water levels time series allowed for the identification of two main periods: March to October and November to February. The first period corresponded to a high level period, recording a maximum level of 200.06 m. The second period, from November to March, was characterized by a drop in the water level, recording a minimum level of 187.42 m. The water levels time series provided by Sentinel-3 allowed us to appreciate the respective influences of seasonal and interannual variations on rainfall and the contributions of the Sassandra River tributaries to the water levels of Lake Buyo.

Impacts of soil properties on bluff recession under combined waves and surge actions: An experimental study with uncertainty quantification

Soil mixtures with five fines contents, two water contents, and two relative densities underwent soil mechanics tests to quantify their strength indices. Then small-scale steep beaches and bluff models were built with those soil mixtures in a small wave flume and subjected to varying water levels and waves. The equilibrium beach profile of the model containing a higher fines content, higher relative density, and the optimum water content, followed a concave down profile, while that of the models with the lower density and/or lower fines content, was concave up. The bluffs composed of the materials with the optimum water content exhibited a reduced crest recession compared to those with the constituent materials dry of optimum. The recession rate of the bluff crest decreased with the increase of the effective cohesion. For a given effective cohesion, the recession rate was significantly influenced by the relative density. The impact of the effective cohesion on the recession rate for the bluff composed of the looser soil was significantly greater than that of the bluffs with the denser constituent material. Furthermore, uncertainties associated with the impacts of the variations in the fines content, relative density, and water content on the recession rate were quantified.

Investigation on the hump region generation mechanism of pump mode in low-head pumped hydro-storage unit

The pump mode of the low-head pumped hydrostorage unit (pump-turbine) may operate in the hump region under extreme conditions due to the influence of water level variation, and the resulting energy conversion instability will seriously threaten the safety of the unit. However, the generation mechanism of the hump region is still not sufficiently understood, which is mainly due to two reasons: the dominant unstable flow structures that induce the formation of the hump region have not been uniformly recognized, and the influence of the dominant unstable flow structures on the impeller's working capacity has not been effectively revealed. In this study, experiments and numerical simulations were carried out on the low-head pumped hydrostorage unit in the pump mode, and the following results were obtained. It is found that the dominant unstable flow structures that induce the formation of the hump region are the leading edge backflow on the blade inlet shroud side and the horn-like vortex on the blade outlet hub side. The leading edge backflow reduces the blade loading and limits the impeller's working capacity, and the horn-like vortex increases the blade loading and increases the impeller's working capacity. The analysis revealed that the formation of the hump region is the result of the mutual restriction of the horn-like vortex and the leading edge backflow.

A Numerical Investigation of Hurricane Florence‐Induced Compound Flooding in the Cape Fear Estuary Using a Dynamically Coupled Hydrological‐Ocean Model

AbstractHurricane‐induced compound flooding is a combined result of multiple processes, including overland runoff, precipitation, and storm surge. This study presents a dynamical coupling method applied at the boundary of a processes‐based hydrological model (the hydrological modeling extension package of the Weather Research and Forecasting model) and the two‐dimensional Regional Ocean Modeling System on the platform of the Coupled‐Ocean‐Atmosphere‐Wave‐Sediment Transport Modeling System. The coupled model was adapted to the Cape Fear River Basin and adjacent coastal ocean in North Carolina, United States, which suffered severe losses due to the compound flood induced by Hurricane Florence in 2018. The model's robustness was evaluated via comparison against observed water levels in the watershed, estuary, and along the coast. With a series of sensitivity experiments, the contributions from different processes to the water level variations in the estuary were untangled and quantified. Based on the temporal evolution of wind, water flux, water level, and water‐level gradient, compound flooding in the estuary was categorized into four stages: (I) swelling, (II) local‐wind‐dominated, (III) transition, and (IV) overland‐runoff‐dominated. A nonlinear effect was identified between overland runoff and water level in the estuary, which indicated the estuary could serve as a buffer for surges from the ocean side by reducing the maximum surge height. Water budget analysis indicated that water in the estuary was flushed 10 times by overland runoff within 23 days after Florence's landfall.

Water Level and Quality Variations of CO2-rich Groundwater and Its Surrounding Geology in the Chungju Angseong Spa Area, South Korea: Considerations on Its Sustainability

Water Level and Quality Variations of CO₂-rich Groundwater and Its Surrounding Geology in the Chungju Angseong Spa Area, South Korea: Considerations on Its Sustainability

Evidence for increasing influence of atmospheric teleconnections on water levels in the Great Lakes

Understanding the variability and predominant drivers of water level fluctuations in large water bodies is critical for the development of proactive mitigation plans in the nearshore zone. Here, for the first time, we reconstructed the individual and collective influence of the Atlantic Multi-decadal Oscillation, Pacific Decadal Oscillation, region 3.4 of El Niño-Southern Oscillation, and North Atlantic Oscillation on Lake Huron-Michigan’s water budget components, including water levels, over-lake precipitation, evaporation, runoff, and river flow rates over a 115-year period. Conducting wavelet spectral analysis on the reconstructed impact of large-scale climate oscillations revealed the emergence of quasi-periodic and non-stationary fluctuations along with frequency shifts in hydrological variables, highlighting their increasingly stronger signature on water levels after 1980. After removing the atmospheric teleconnection effects, the residual hydrological time series provided evidence of gradual changes in runoff and river flow rates and their relationships with precipitation, reflecting the effects of intensifying anthropogenic activities on the regional water cycle over the past decades. Considering the uncertainty pertaining to the magnitude and frequency of atmospheric teleconnections in a changing climate, the findings of our study can offer a new perspective in our understanding of the drivers of water level variability along the shoreline and/or the navigability of shallow waters in the Great Lakes.

Interspecific differences in brood desertion by female diving ducks in relation to duckling age and environmental conditions

Studies on brood desertion in birds have been mainly conducted on species with biparental care, and less often on uniparental species. Females of many duck species remain with their ducklings, unassisted by males, during variable periods of time before the chicks can fledge. In this paper, we examined factors that influence brood desertion by female red-crested pochards ( Netta rufina), common pochards ( Aythya ferina) and white-headed ducks ( Oxyura leucocephala) during a 10-year period in lakes in southern Spain that experienced interannual variations in water levels. At an interspecific level, we found that brood desertion was less frequent in the species that nested earlier (red-crested pochard), while it was more frequent in the species that nested later (white-headed duck). Larger (older) ducklings were deserted more frequently than smaller ones in the three species. However, an interaction between flooding conditions in wetlands and species identity on brood desertion, after accounting for chick age, suggests that there were variations between the ducklings of the three species in their requirements for maternal care, conditioned by environmental conditions. Therefore, our study indicates that environmental conditions may affect parental care. A longer duration of brood attendance by female ducks may buffer against adverse effects of environmental conditions.