Your browser doesn't support javascript.
loading
Mostrar: 20 | 50 | 100
Resultados 1 - 20 de 1.730
Filtrar
1.
J Environ Manage ; 279: 111506, 2021 Feb 01.
Artigo em Inglês | MEDLINE | ID: mdl-33168300

RESUMO

Watershed-scale hydrologic models are frequently used to inform conservation and restoration efforts by identifying critical source areas (CSAs; alternatively 'hotspots'), defined as areas that export relatively greater quantities of nutrients and sediment. The CSAs can then be prioritized or 'targeted' for conservation and restoration to ensure efficient use of limited resources. However, CSA simulations from watershed-scale hydrologic models may be uncertain and it is critical that the extent and implications of this uncertainty be conveyed to stakeholders and decision makers. We used an ensemble of four independently developed Soil and Water Assessment Tool (SWAT) models and a SPAtially Referenced Regression On Watershed attributes (SPARROW) model to simulate CSA locations for flow, phosphorus, nitrogen, and sediment within the ~17,000-km2 Maumee River watershed at the HUC-12 scale. We then assessed uncertainty in CSA simulations determined as the variation in CSA locations across the models. Our application of an ensemble of models - differing with respect to inputs, structure, and parameterization - facilitated an improved accounting of CSA prediction uncertainty. We found that the models agreed on the location of a subset of CSAs, and that these locations may be targeted with relative confidence. However, models more often disagreed on CSA locations. On average, only 16%-46% of HUC-12 subwatersheds simulated as a CSA by one model were also simulated as a CSA by a different model. Our work shows that simulated CSA locations are highly uncertain and may vary substantially across models. Hence, while models may be useful in informing conservation and restoration planning, their application to identify CSA locations would benefit from comprehensive uncertainty analyses to avoid inefficient use of limited resources.


Assuntos
Fósforo , Solo , Hidrologia , Modelos Teóricos , Nitrogênio/análise , Fósforo/análise , Incerteza
2.
Chemosphere ; 266: 129008, 2021 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-33261839

RESUMO

Due to human activity and global climate change, the Yellow River Delta, the youngest delta wetland in China, is suffering serious degradation. The study of hydrological connection provides new perspectives and technical support for the protection and restoration of delta wetlands. To quantify the interaction between the hydrological connection and the root-soil complex, the current study took dye-tracing experiments to examine the small-scale hydrological connectivity in soil where Phramites australis grew. The dye coverage was selected as the indicator of hydrological connectivity after preliminary analysis in this study. The main results were that (1) the strength of hydrological connectivity was negatively related to the microaggregates content, but had little to do with other soil physical properties; (2) there was a notable positive correlation between the indexes of thick root (D > 5 mm) and the dye coverage hydrological connectivity, while root biomass had little effect on hydrological connectivity; and (3) the influence of the microaggregate content dominated in the combined effect of the total surface area of the root (D > 5 mm) and the microaggregate content on hydrological connectivity in each soil layer.


Assuntos
Hidrologia , Áreas Alagadas , China , Humanos , Rios , Solo
3.
Sci Total Environ ; 750: 142081, 2021 Jan 01.
Artigo em Inglês | MEDLINE | ID: mdl-33182185

RESUMO

The high biotic diversity supported by floodplains is ruled by the interplay of geomorphic and hydrological processes at various time scales, from daily fluctuations to decennial successions. Because understanding such processes is a key question in river restoration, we attempted to model changes in taxonomic richness in an assemblage of 58 macroinvertebrate taxa (21 gastropoda and 37 ephemeroptera, plecoptera and trichoptera, EPT) along two successional sequences typical for former braided channels. Individual models relating the occurrence of taxa to overflow and backflow durations were developed from field measurements in 19 floodplain channels of the Rhône floodplain (France) monitored over 10 years. The models were combined to simulate diversity changes along a progressive alluviation and disconnection sequence after the reconnection with the main river of a previously isolated channel. Two scenarios were considered: (i) an upstream + downstream reconnection creating a lotic channel, (ii) a downstream reconnection creating a semi-lotic channel. Reconnection led to a direct increase in invertebrate richness (on average x2.5). However, taxonomical richness showed a constant decrease as isolation progressed and reached an average of 2 for EPT and 7 for gastropods at the end of the scenarios. With more than 80% of the taxonomic models with an AUC equal or higher than 0.7 and slopes of linear relations between observed and predicted richness of 0.75 (gastropods) and 1 (EPT), the Boosted Regression Trees (BRT) provided a good basis for prediction of species assemblages. These models can be used to quantify a priori the sustainability and ecological efficiency of restoration actions and help floodplain restoration planning and management.


Assuntos
Ecossistema , Invertebrados , Animais , França , Hidrologia , Rios
4.
J Environ Manage ; 278(Pt 1): 111524, 2021 Jan 15.
Artigo em Inglês | MEDLINE | ID: mdl-33126187

RESUMO

Human-induced changes in land and water resources adversely affect global hydrological regimes. Hydrological alteration of the natural flow regime is considered to have a significant damaging and widespread impact on river ecosystems and livelihoods. Therefore, understanding the hydrological alteration of rivers and the potential driving factors affecting such alterations are crucial to effective water resources management. This study analyses the impact of changes in land use, climate, and hydropower development on the hydrological regime of the Srepok River Basin in the Lower Mekong Region. The Lower Mekong Basin (LMB) in Southeast Asia is known for its agriculture, forests, fisheries, wildlife, and diverse natural ecosystems. Historical land use and climate change are quantified (utilising European Space Agency land cover and observed meteorological data) and correlated with the hydrological indicators using the Indicators of Hydrologic Alteration (IHA) software. Moreover, pre and post impacts on the hydrological regime by hydropower development are quantified using the Range of Variability Approach (RAV) in IHA software. The results reveal that land use, rainfall, and temperature affect different aspects of the hydrological regime, with corroborating evidence to support variation among the most correlated IHA and environmental flow component (EFC) parameters with the three drivers. The highest and lowest correlations among the IHA and EFC parameters under each driver are against land use (0.85, -0.83), rainfall (0.78, -0.54), and minimum and max temperatures (0.42, -0.47). Among the parameters, the fall rate has the most significant effect on hydrological alteration of all drivers. Hydropower development in the basin mostly affects the fall rate and reversal. Identifying the connection between these multiple drivers and hydrological alteration could help decision-makers to design more efficient and sustainable water management policies.


Assuntos
Ecossistema , Rios , Ásia Sudeste , Hidrologia , Movimentos da Água
5.
Water Res ; 188: 116477, 2021 Jan 01.
Artigo em Inglês | MEDLINE | ID: mdl-33137527

RESUMO

Historically, little consideration has been given to water performance of urban developments such as "hydrological naturalness" or "local water self-sufficiency". This has led to problems with increased stormwater runoff, flooding, and lack of local contributions to urban water security. Architectural design, water servicing technologies and environmental conditions are each known to influence water performance. However, most existing models have overlooked the integration of these factors. In this work, we asked 'how the water performance of urban developments at site-scale can be quantified, with joint consideration of architectural design, water servicing technologies, and environmental context (i.e. climate and soil)'. Answering this question led to the development of a new method and tool called Site-scale Urban Water Mass Balance Assessment (SUWMBA). It uses a daily urban water mass balance to simulate design-technology-environment configurations. Key features include: (i) a three-dimensional boundary focussed on the "entity" of development (ii) a comprehensive water balance accounting for all urban water flows, (iii) methods that include key variables capturing the interactions of natural, built-environment and socio-technological systems on water performance. SUWMBA's capabilities were demonstrated through an evaluation of a residential infill development case study with alternative design-technology-environment configurations, combining three dwelling designs, seven water technologies and three environmental contexts. The evaluation showed how a configuration can be identified that strikes a balance between the conflicting objectives of achieving the desired dwelling densities whilst simultaneously improving water performance. For two climate zones, the optimal configuration increases the total number of residents by 300% while reducing the imported water per capita and stormwater discharge by 45% and 15%, respectively. We infer that SUWMBA could have strong potential to contribute to performance-based urban design and planning by enabling the water performance of dwelling designs to be quantified, and by facilitating the setting of locally-specific water performance objectives and targets.


Assuntos
Conservação dos Recursos Naturais , Abastecimento de Água , Cidades , Hidrologia , Chuva , Tecnologia , Água
6.
J Environ Manage ; 277: 111393, 2021 Jan 01.
Artigo em Inglês | MEDLINE | ID: mdl-33075655

RESUMO

Among the input data of the watershed model for simulating changes of flowrate in the watershed, weather input data, especially input data related to rainfall, are the most important. Therefore, it is important to ensure the accuracy of rainfall input data to increase the accuracy of the watershed model results. Securing rainfall measurements with finer spatial and temporal resolutions is important in predicting flowrate variations at a sub-catchment, especially as they relate to global and local climate changes in weather conditions such as rainfall depth, rainfall intensity, etc. In this study, adjusted radar-rainfall estimates were suggested as alternative input data for watershed modeling. Through a statistical analysis of the representativeness of a ground rainfall measurement (10 km × 10 km grid), the necessity of radar-rainfall estimates (2 km × 2 km grid) was identified. By applying calibration factors to initial radar-rainfall estimates and comparing adjusted radar-rainfall estimates with ground rainfall measurements, it was proven that adjusted radar-rainfall estimates could be used as input data for watershed simulations (NSE > 0.92; n = 12). Adjusted radar-rainfall estimates and ground rainfall measurements were used as input data of the Soil and Water Assessment Tool model to predict flowrate variations at the outlets of a tributary and the entire watershed. As a result, the accuracies of the simulation results were improved for the outlets of a tributary and the entire watershed (NSE: 0.33 to 0.48 and 0.19 to 0.55, respectively). To obtain more reliable rainfall data, radar images easily accessible to users were applied, and the accuracy of the data was increased by applying simple equations to numerical data extracted from radar image processing. Additionally, the applicability of the adjusted radar-rainfall estimates was demonstrated by comparing the modeling results using the suggested rainfall data and existing ground-based rainfall data. The suggested methodologies are expected to contribute to more accurately predict the possibility of flood disasters in other regions and countries lacking infrastructure related to rainfall measurements and to establish appropriate countermeasures.


Assuntos
Radar , Chuva , Monitoramento Ambiental , Hidrologia , Meteorologia , Modelos Teóricos
7.
J Environ Manage ; 277: 111418, 2021 Jan 01.
Artigo em Inglês | MEDLINE | ID: mdl-33080432

RESUMO

Green roofs are among the most popular type of green infrastructure implemented in highly urbanized watersheds due to their low cost and efficient utilization of unused or under-used space. In this study, we examined the effectiveness of green roofs to attenuate stormwater runoff across a large metropolitan area in the Pacific Northwest, United States. We utilized a spatially explicit ecohydrological watershed model called Visualizing Ecosystem Land Management Assessments (VELMA) to simulate the resulting stormwater hydrology of implementing green roofs over 25%, 50%, 75%, and 100% of existing buildings within four urban watersheds in Seattle, Washington, United States. We simulated the effects of two types of green roofs: extensive green roofs, which are characterized by shallow soil profiles and short vegetative cover, and intensive green roofs, which are characterized by deeper soil profiles and can support larger vegetation. While buildings only comprise approximately 10% of the total area within each of the four watersheds, our simulations showed that 100% implementation of green roofs on these buildings can achieve approximately 10-15% and 20-25% mean annual runoff reductions for extensive and intensive green roofs, respectively, over a 28-year simulation. These results provide an upper limit for volume reductions achievable by green roofs in these urban watersheds. We also showed that stormwater runoff reductions are proportionately smaller during higher flow regimes caused by increased precipitation, likely due to the limited storage capacity of saturated green roofs. In general, green roofs can be effective at reducing stormwater runoff, and their effectiveness is limited by both their areal extent and storage capacity. Our results showed that green roof implementation can be an effective stormwater management tool in highly urban areas, and we demonstrated that our modeling approach can be used to assess the watershed-scale hydrologic impacts of the widespread adoption of green roofs across large metropolitan areas.


Assuntos
Hidrologia , Movimentos da Água , Conservação dos Recursos Naturais , Ecossistema , Chuva , Washington
8.
J Environ Radioact ; 226: 106354, 2021 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-33046265

RESUMO

Tritium, the radioactive isotope of hydrogen, has been used to understand groundwater recharge processes for decades. The current variation of tritium in the atmosphere is largely attributed to stratospheric production and fall out rates as well as global circulation phenomena controlling the hydrological cycle. Global controls on the variability in atmospheric tritium activity are poorly suited to explain local variation and tritium activities in precipitation are often assumed to be uniform over both local and regional catchments and watersheds. This assumption can result in both over and under estimation of modern recharge within an aquifer when using tritium as the recharge proxy. In order to minimize the inherent prediction residuals associated with tritium based recharge investigations, the variability of tritium in precipitation was modelled from 127 spatial precipitation samples taken over a two year period, combined with a 76 precipitation sample group-set taken over a one year period in a single location. Precipitation events were traced backward in time, from the point of collection, using HYSPLIT modelling to ascertain the origins of moisture content as well as the altitudes of moisture origin reached along the particle track. Tritium activities, collected over a one year period in Paarl, range from 0.45 to 4.16 TU and have a mean of 1.59 TU. Spatial storm events in the Western Cape in 2017 and 2018 had a range from 0 to 2.2 and 0.37 to 3.27 TU, respectively, with mean activities of 1.18 (n = 34) and 1.25 TU (n = 32). Both storm events had similar tritium variability (σ = 0.5 n = 35 and 0.48 n = 32). Regional precipitation events had the largest range of tritium activities (0.55-12.2 TU). Although not all tritium activities can be explained by interrogating the water mass origin, this study suggests that approximately 90% of events can be completely or partially attributed to the origin of the water mass. The variability of tritium, both spatially and temporally, was higher than expected, confirming that when uniform tritium inputs are used, the groundwater system would provide inaccurate modern recharge estimates. Higher spatial resolution of tritium variation in precipitation for a particular region will improve our ability to relate tritium activities in groundwater to local precipitation.


Assuntos
Monitoramento de Radiação , Trítio/análise , Água Subterrânea , Hidrologia , África do Sul
9.
Sci Total Environ ; 755(Pt 2): 142503, 2021 Feb 10.
Artigo em Inglês | MEDLINE | ID: mdl-33045606

RESUMO

Changes in climate are known to alter air temperature and precipitation and their associated thermal and hydrological regimes of freshwater systems, and such alterations in habitat are anticipated to modify fish composition in fluvial systems. Despite these expected changes, assessing climate change effects on habitat and fish over large regions has proven challenging. The goal of this study is to describe an approach to assess and identify stream reaches within a large region that are susceptible to climate changes based on responses of multiple fish species to changes in thermal and hydrological habitats occurring with changes in climate. We present a six-step approach to connect climate, habitat, and fish responses, demonstrated through an example to assess effects of climate change on fishes for all stream reaches in a large U.S. ecoregion (955,029 km2). Step 1 identified measures of air temperature and precipitation expected to change substantially in the future. Step 2 identified the climatic measures strongly associated with stream thermal and hydrologic metrics calculated from measured data from a subset of streams. Step 3 linked thermal and hydrologic metrics identified in Step 2 with abundances of fish species from the same stream reaches, and these fishes were combined into groups based on similar associations with specific thermal or hydrologic metrics. Step 4 used the linkages between fish groups and climatic measures and their associated thermal and hydrologic metrics to classify stream reaches. Step 5 assigned all stream reaches into classes based on the established classification under current climate measures and then re-assigned all stream reaches using projected climatic measures for three future time windows. Step 6 assessed changes in classes of stream reaches between current and future climate conditions. Stream reaches projected to change in stream classes were considered "vulnerable" to future climate change, as they would no longer support the same fish composition. The projected vulnerable streams for the years 2040, 2060, and 2090 were mapped and summarized to identify temporal patterns and identify their spatial distribution, along with underlying mechanisms leading to changes. Our results showed that 45.7% of the 320,000 reaches and 49.3% of the overall 650,000 km stream length in the study region were expected to change stream class by the year 2090, with spatially-explicit changes including streams' responding to changing air temperature or precipitation. This study provides critical guidance for integrating climate projections, landscape factors, stream habitat data, and fish data into a meaningful approach for understanding linkage. Outcomes greatly improve our ability to describe habitat changes at a stream reach scale throughout large regions, and they can aid in prioritizing management strategies to adapt to climate change at local and regional scales.


Assuntos
Ecossistema , Rios , Animais , Mudança Climática , Peixes , Hidrologia
10.
J Environ Manage ; 278(Pt 2): 111559, 2021 Jan 15.
Artigo em Inglês | MEDLINE | ID: mdl-33137686

RESUMO

Given rapid environmental change, the development of new, data-driven, interdisciplinary approaches is essential for improving assessment and management of river systems, especially with respect to flooding. In the world's extensive drylands, difficulties in obtaining field observations of major hydrological events mean that remote sensing techniques are commonly used to map river floods and assess flood impacts. Such techniques, however, are dependent on available cloud-free imagery during or immediately after peak discharge, and single images may omit important flood-related hydrogeomorphological events. Here, we combine multiple Landsat images from Google Earth Engine (GEE) with precipitation datasets and high-resolution (<0.65 m) satellite imagery to visualise flooding and assess the associated channel-floodplain dynamics along a 25 km reach of the unvegetated, ephemeral Río Colorado, Bolivia. After cloud and shadow removal, Landsat surface reflectance data were used to calculate the Modified Normalized Difference Water Index (MNDWI) and map flood extents and patterns. From 2004 through 2016, annual flooding area along the narrow (<30 m), shallow (<1.7 m), fine-grained (dominantly silt/clay) channels was positively correlated (R2 = 0.83) with 2-day maximum precipitation totals. Rapid meander bend migration, bank erosion, and frequent overbank flooding was associated with formation of crevasse channels, splays, and headward-eroding channels, and with avulsion (shifting of flow from one channel to another). These processes demonstrate ongoing, widespread channel-floodplain dynamics despite low stream powers and cohesive sediments. Application of our study approaches to other dryland rivers will help generate comparative data on the controls, rates, patterns and timescales of channel-floodplain dynamics under scenarios of climate change and direct human impacts, with potential implications for improved river management.


Assuntos
Inundações , Rios , Agricultura , Colorado , Humanos , Hidrologia
11.
J Environ Manage ; 278(Pt 2): 111486, 2021 Jan 15.
Artigo em Inglês | MEDLINE | ID: mdl-33157463

RESUMO

Increased flooding, droughts, and sediment transport are watershed-scale problems negatively impacting agriculture and ecosystems in drylands worldwide. Vegetation loss in upland watersheds is leading to scouring floods, which in turn decreases infiltration, soil moisture levels, and downstream groundwater recharge. Management to confront these intractable problems has been hindered by a lack of accessible decision support tools for both land and water managers that synthesize the watershed processes that buffer against dryland disturbances. Flood flow connectivities across the landscape create buffer zones through replenishing soil moisture and reducing flood energy, which in turn support multiple functions. This study developed a decision support tool, the Flood Flow Connectivity to the Landscape (FlowCon) framework that quantifies the most efficient management efforts to increase the key watershed buffering functions of increasing infiltration and reducing flow energy. FlowCon links three spatially explicit, process-based, and predictive models to answer two critical management questions: what key processes acting in what optimal areas are drivers of infiltration dynamics and what roles do peak flows of differing scales of energy play. The spatial models delineated the buffer zone to characterize the heterogeneous and optimal infiltration dynamics across the landscape. The hydrologic process model, using a curve number technique, identified the key ecohydrologic processes that affect infiltration and characterized peak flows and flow regime variability. The predictive flood routing model quantified the potential management benefits. We calibrated the models with measured runoff and the corresponding rainfall events for a six-year period, which included thirty-six flow events. The synthesized ecohydrologic indicators provided critical calibrations, improving the relationship between the hydrologic modeling results and observed data by 12% for the linear regression R2 and 69% for the root mean square error (RMSE). Implementation of prioritized management is estimated to reduce peak flow by half, with interventions focused on 24% of floodplains that infiltrate three times the flow volume per area than the floodplain average. FlowCon provides an efficient assessment framework that integrates watershed process understanding in an accessible decision support tool to achieve tangible improvements in dryland watershed management.


Assuntos
Inundações , Água Subterrânea , Ecossistema , Hidrologia , Solo
12.
BMC Ecol ; 20(1): 70, 2020 12 17.
Artigo em Inglês | MEDLINE | ID: mdl-33334346

RESUMO

BACKGROUND: Earlier breeding is one of the strongest responses to global change in birds and is a key factor determining reproductive success. In most studies of climate effects, the focus has been on large-scale environmental indices or temperature averaged over large geographical areas, neglecting that animals are affected by the local conditions in their home ranges. In riverine ecosystems, climate change is altering the flow regime, in addition to changes resulting from the increasing demand for renewable and clean hydropower. Together with increasing temperatures, this can lead to shifts in the time window available for successful breeding of birds associated with the riverine habitat. Here, we investigated specifically how the environmental conditions at the territory level influence timing of breeding in a passerine bird with an aquatic lifestyle, the white-throated dipper Cinclus cinclus. We relate daily river discharge and other important hydrological parameters, to a long-term dataset of breeding phenology (1978-2015) in a natural river system. RESULTS: Dippers bred earlier when winter river discharge and groundwater levels in the weeks prior to breeding were high, and when there was little snow in the catchment area. Breeding was also earlier at lower altitudes, although the effect dramatically declined over the period. This suggests that territories at higher altitudes had more open water in winter later in the study period, which permitted early breeding also here. Unexpectedly, the largest effect inducing earlier breeding time was territory river discharge during the winter months and not immediately prior to breeding. The territory river discharge also increased during the study period. CONCLUSIONS: The observed earlier breeding can thus be interpreted as a response to climate change. Measuring environmental variation at the scale of the territory thus provides detailed information about the interactions between organisms and the abiotic environment.


Assuntos
Hidrologia , Passeriformes , Animais , Cruzamento , Mudança Climática , Ecossistema
13.
Water Sci Technol ; 82(12): 2635-2670, 2020 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-33341760

RESUMO

The global volume of digital data is expected to reach 175 zettabytes by 2025. The volume, variety and velocity of water-related data are increasing due to large-scale sensor networks and increased attention to topics such as disaster response, water resources management, and climate change. Combined with the growing availability of computational resources and popularity of deep learning, these data are transformed into actionable and practical knowledge, revolutionizing the water industry. In this article, a systematic review of literature is conducted to identify existing research that incorporates deep learning methods in the water sector, with regard to monitoring, management, governance and communication of water resources. The study provides a comprehensive review of state-of-the-art deep learning approaches used in the water industry for generation, prediction, enhancement, and classification tasks, and serves as a guide for how to utilize available deep learning methods for future water resources challenges. Key issues and challenges in the application of these techniques in the water domain are discussed, including the ethics of these technologies for decision-making in water resources management and governance. Finally, we provide recommendations and future directions for the application of deep learning models in hydrology and water resources.


Assuntos
Aprendizado Profundo , Recursos Hídricos , Mudança Climática , Hidrologia
14.
Ying Yong Sheng Tai Xue Bao ; 31(11): 3833-3841, 2020 Nov.
Artigo em Chinês | MEDLINE | ID: mdl-33300734

RESUMO

Quantitative assessment of hydrological connectivity is a hot but difficult issue in current research. Using the 30-m resolution global monthly surface water remote sensing dataset released by the EU Joint Research Center and three indicators of geostatistical connectivity, maximum distance of connection (MDC), and surface water extent of connectome (i.e., seasonally connected water bodies), we quantified the hydrological connectivity of surface water in Momoge National Nature Reserve in different months of a normal year (May to October 2016), and in September of different hydrological years (a wet year, namely 1998; a normal year, namely 2016; a drought year, namely 2002), and different directions (west-east and north-south). Our results showed that: 1) the geostatistical connectivity function (GCF) along the west-east direction was better than that along the north-south direction. The GCF in August and July was better than that in other months. The GCF along the west-east direction of each hydrological year was better than that in the drought year, whereas the GCF in the drought year was better than the corresponding value in the normal year. The GCF along the north-south direction in each hydrological year was better than that in the normal year, whereas the GCF in the normal year was better than that in the drought year. The MDC along the west-east direction in June, July, September, and October of the normal year was all concentrated at 25.26 km. MDC was more concentrated along the north-south direction, with 10 km for all months. The MDC in the normal and drought years was relatively close, but both were much smaller than that in the wet year. 2) frequent seasonal connections between the Yuelianghu Reservoir and the Nenjiang River, and between Etoupao and its neighboring lakes occurred in the study area during the normal year, while most of the other lakes remained isolated. The patterns of hydrological connection in the study area differed across different hydrological years: two giant connectomes were formed in the wet year, some lakes are periodically connected in the normal year, and all lakes remain isolated in the drought year. 3) As a drainage area for farmland receding water, the surface water extent of the Etoupao connectome increased visibly during the three water supplement seasons (spring, summer, and autumn). By quantifying the surface hydrological connectivity in Momoge National Nature Reserve with multiple water sources from different perspectives, our results provide a scientific basis for wetland protection and restoration and integrated management of watershed water resources.


Assuntos
Hidrologia , Rios , China , Secas , Áreas Alagadas
15.
Sci Rep ; 10(1): 16276, 2020 10 01.
Artigo em Inglês | MEDLINE | ID: mdl-33004918

RESUMO

On Conch Reef, Florida Keys, USA we examined the effects of reef hydrography and topography on the patterns of stable isotope values (δ18O and δ13C) in the benthic green alga, Halimeda tuna. During the summer, benthic temperatures show high-frequency fluctuations (2 to 8 °C) associated with internal waves that advected cool, nutrient-rich water across the reef. The interaction between local water flow and reef morphology resulted in a highly heterogenous physical environment even within isobaths that likely influenced the growth regime of H. tuna. Variability in H. tuna isotopic values even among closely located individuals suggest biological responses to the observed environmental heterogeneity. Although isotopic composition of reef carbonate material can be used to reconstruct past temperatures (T(°C) = 14.2-3.6 (δ18OHalimeda - δ18Oseawater); r2 = 0.92), comparing the temperatures measured across the reef with that predicted by an isotopic thermometer suggests complex interactions between the environment and Halimeda carbonate formation at temporal and spatial scales not normally considered in mixed sediment samples. The divergence in estimated range between measured and predicted temperatures demonstrates the existence of species- and location-specific isotopic relationships with physical and environmental factors that should be considered in contemporary as well as ancient reef settings.


Assuntos
Clorófitas/metabolismo , Recifes de Corais , Florida , Hidrologia , Biologia Marinha , Isótopos de Oxigênio/metabolismo , Radioisótopos de Oxigênio/metabolismo , Paleontologia , Água do Mar , Temperatura
16.
Sci Total Environ ; 748: 141375, 2020 Dec 15.
Artigo em Inglês | MEDLINE | ID: mdl-33113681

RESUMO

Storm runoff is important for maintaining surface water resources, while this function is significantly affected by land use and land cover changes, e.g., afforestation and reforestation. The Chinese Loess Plateau (CLP) has undergone large-scale vegetation rehabilitation, especially afforestation over the past 20 years. We hypothesize that afforestation has profoundly changed the amounts and mechanisms of storm runoff generation in headwater catchments on the CLP. To test this hypothesis, rainfall, soil moisture, and streamflow were monitored in a grass catchment and an adjacent forest catchment for two consecutive years. The objective of this study was to elucidate the varied mechanisms of storm runoff generation in these two contrasting revegetated catchments. Results showed that (1) average runoff coefficient in the grassland catchment (0.042) was approximately ten times higher than that in the forestland catchment (0.004), confirming the impact of catchment afforestation on the suppression of storm runoff generation. (2) Peak rainfall intensity was the first-order control of the runoff coefficient in the grassland catchment, but not in the forestland catchment. (3) Threshold values for antecedent soil moisture (~18%) and the sum of antecedent soil moisture index and event precipitation (~210 mm) were identified in the grassland catchment, above which storm runoff significantly increased. (4) Two extraordinary high runoff coefficient events were observed in the grassland catchment, one due to high peak rainfall intensity and strong surface runoff and the other due to high rainfall amount and high antecedent soil moisture. We conclude that long-term afforestation has changed the mechanisms and patterns of storm runoff generation, and different conditions of rainfall intensity, rainfall amount and antecedent soil moisture determined the hydrological connectivity between the upper hillslope and downhill gully in the catchment. This study deepens our understanding of the mechanisms and thresholds of storm runoff generation in headwater catchments on the CLP.


Assuntos
Chuva , Movimentos da Água , Hidrologia , Poaceae , Solo
17.
Environ Monit Assess ; 192(11): 707, 2020 Oct 17.
Artigo em Inglês | MEDLINE | ID: mdl-33068183

RESUMO

Among the problems related to water security, the effects of climate change on water availability stand out. Researchers have used hydrological models integrated with climate models in order to predict the streamflow behaviour in different hydrographic basins. This work aimed to analyse future climate scenarios for the Ribeirão do Lobo River Basin, located in the state of São Paulo, Brazil. The stochastic generator PGECLIMA_R was used in the simulation of climate data, which were used as input data in the hydrological model SMAP, after it was calibrated and validated for the study site. In all, five future scenarios were generated, with scenarios A, B, C and D projected based on the 5th report of the IPCC and scenario E based on the trend of climate data in the region. Among the scenarios generated, scenario D, which considers an increase of 4.8 °C in air temperature and a reduction of 10% in rainfall, is responsible for the worst water condition in the basin and can reduce up to 72.41% of the average flow and up to 55.50%, 54.18% and 38.17% of the low flow parameters Q90%, Q95% and Q7,10, respectively, until the end of the twenty-first century. However, the E scenario also becomes a matter of concern, since it was responsible for greater increases in temperature and greater reductions in rainfall and, consequently, more drastic monthly reductions in streamflow, which may negatively impact water resources and affect the various uses of water in the Ribeirão do Lobo River Basin.


Assuntos
Mudança Climática , Modelos Teóricos , Brasil , Monitoramento Ambiental , Hidrologia
18.
Environ Monit Assess ; 192(11): 689, 2020 Oct 08.
Artigo em Inglês | MEDLINE | ID: mdl-33030599

RESUMO

Flooding in urban basins is a major natural catastrophe that leads to many causalities of life and property. The semi-urbanized Koraiyar River basin in Tamil Nadu has important cities like Tiruchirappalli and many towns located in it. The basin unfailingly experiences a flood event in almost every decade. It is anticipated that the basin will undergo rapid unplanned urbanization in the years to come. Such fast and erratic urban developments will only increase the risk of urban floods ultimately resulting in loss of human lives and extensive damages to property and infrastructure. The effects of urbanization can be quantified in the form of land use land cover (LULC) changes. The LULC change and its impacts on urban runoff are studied for the continuous 30-year present time period of (1986-2016) to reliably predict the anticipated impact in the future time period of (2026-2036). The analysis of land cover patterns over the years shows that urbanization is more prevalent in the northern part of the basin of the chosen study area when compared with the other regions. The extreme rainfall events that occurred in the past, and the probable future LULC changes, as well as their influence on urban runoff, are studied together in the current study. In order to minimize flood damages due to these changing land use conditions, certain preventive and protective measures have to be adopted at the earliest. There are some inevitable limitations while applying traditional measures in flood modeling studies. This investigative work considers a case study on the ungauged Koraiyar floodplains. The spatial scale risk assessment is assessed by coupling geographic information systems, remote sensing, hydrologic, and hydraulic modeling, to estimate the flood hazard probabilities in the Koraiyar basin. The maximum flood flow is generated from the Hydrologic Engineering Centre-Hydrologic Modeling System (HEC-HMS), the hydrologic model adopted in the present study. The maximum flood flow is given as input to the Hydrologic Engineering Centre-River Analysis System (HEC-RAS), an effective hydraulic model that generates water depth and flood spread area in the basin. The flood depth and hazard maps are derived for 2, 5, 10, 50, and 100-year return periods. From the analysis, it is observed that the minimum flood depth is less than 1.2 m to a maximum of 4.7 m for the 100-year return period of past to predicted future years. The simulated results show that the maximum flood depth of 4.7 m with flood hazard area of 4.32% is identified as high hazard zones from the years 1986-2036, located in the center of the basin in Tiruchirappalli city. The very high hazard flood-affected zone in the Koraiyar basin during this period is about 198.85 km2. It is noticed that the very low hazard zone occupies more area in the basin for the present and future simulations of flood hazard maps. The results show that the increase in peak runoff and runoff volume is marginally varied.


Assuntos
Monitoramento Ambiental , Inundações , Cidades , Hidrologia , Índia
19.
J Environ Qual ; 49(3): 723-734, 2020 May.
Artigo em Inglês | MEDLINE | ID: mdl-33016394

RESUMO

Groundwater withdrawal has increased over the past several decades throughout the U.S. Upper Midwest, yet impacts of pumping on groundwater-dependent wetlands remain understudied. Here, we compared measures of floristic quality, hydrologic conditions, and nutrient availability in pairs of more-impacted fens and less-impacted fens throughout Wisconsin. Floristic quality was significantly lower in more-impacted fens than in less-impacted fens, the result of the disappearance of rare and specialist species and the increase in richness and cover of non-native and weedy species. Plots within more-impacted fens generally had lower root-zone volumetric water content, greater depth to water table, and higher available nitrogen and phosphorus than within less-impacted fens, although nonuniformly among or within sites. Lower volumetric water content predicted plot-level declines in floristic quality, richness of rare or specialist species, an increase in the number of non-native or problematic species, and an increase in cover of non-native and problematic species. Our results strongly suggest that groundwater withdrawals have substantial negative impacts on nearby fen quality and furthering imperilment of several species they contain.


Assuntos
Água Subterrânea , Hidrologia , Nitrogênio , Áreas Alagadas , Wisconsin
20.
J Environ Qual ; 49(5): 1370-1383, 2020 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-33016447

RESUMO

Recent research on tile-drainage has placed emphasis on dissolved reactive phosphorus (DRP) delivery and transport pathways but less emphasis on particulate P (PP), resulting in its exclusion from agricultural water management models. In this study, we quantified the fluxes, mechanisms, and factors driving PP delivery into tiles through statistical analysis of a long-term hydrologic and water quality dataset. The dataset includes 5 yr of surface and tile discharge, total P (TP), DRP, total nitrogen (TN), and dissolved inorganic N concentrations from two edge-of-field study sites with contrasting soil and management practices. Hydrograph recession techniques were coupled with multiple linear regression for understanding hydrologic flow pathways, and empirical mode decomposition (EMD) time-series analysis was used to determine the significance of PP seasonality processes and the effect of management practices. The analysis of hydrologic flow pathways demonstrated that quickflow contributed 66 and 36% of subsurface discharge in the clay and loam sites, respectively. Phosphorus loading analysis showed that macropore flow plays a significant role in PP delivery to subsurface P loading and that PP significantly contributed to TP and DRP delivery; however, greater PP loadings were observed at the clay site despite greater subsurface discharge and soil test P levels at the loam site. Furthermore, PP delivery was significantly affected by environmental conditions and management practices. We highlight the efficacy of hydrograph recession analysis for identifying macropore and diffuse drainage, of P/N ratios to characterize sediment delivery mechanisms in tiles, and of EMD to detect management impacts on TP and DRP at the field scale.


Assuntos
Fósforo/análise , Movimentos da Água , Agricultura , Hidrologia , Solo
SELEÇÃO DE REFERÊNCIAS
DETALHE DA PESQUISA