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1.
Rev Bras Epidemiol ; 23: e200018, 2020.
Artigo em Português, Inglês | MEDLINE | ID: mdl-32159628

RESUMO

INTRODUCTION: Malaria is an infectious disease of high transmission in the Amazon region, but its dynamics and spatial distribution may vary depending on the interaction of environmental, socio-cultural, economic, political and health services factors. OBJECTIVE: To verify the existence of malaria case patterns in consonance with the fluviometric regimes in Amazon basin. METHOD: Methods of descriptive and inferential statistics were used in malaria and water level data for 35 municipalities in the Amazonas State, in the period from 2003 to 2014. RESULTS: The existence of a tendency to modulate the seasonality of malaria cases due to distinct periods of rivers flooding has been demonstrated. Differences were observed in the annual hydrological variability accompanied by different patterns of malaria cases, showing a trend of remodeling of the epidemiological profile as a function of the flood pulse. CONCLUSION: The study suggests the implementation of regional and local strategies considering the hydrological regimes of the Amazon basin, enabling municipal actions to attenuate the malaria in the Amazonas State.


Assuntos
Hidrologia , Malária/epidemiologia , Estações do Ano , Brasil/epidemiologia , Humanos , Incidência , Malária/diagnóstico , Características de Residência , Rios , Movimentos da Água
2.
J Environ Manage ; 261: 110212, 2020 May 01.
Artigo em Inglês | MEDLINE | ID: mdl-32148282

RESUMO

Hydropower plants are commonly reported as a major cause of the worldwide decline of freshwater eels (Anguillidae), so that management solutions are urgently needed to mitigate their impacts. Where downstream passage solutions are complex to develop, turbine shutdown appears as an effective management solution to protect silver eels during their river migration toward spawning areas. However, the definition of operational decision rules for turbine shutdown is challenging due to the duality between the benefit for eel conservation and the concomitant cost in term of hydropower production. Here, we proposed a decision framework for turbine shutdown based on simple hydrological criteria to guide negotiations between stakeholders toward a trade-off between silver eel escapement and hydropower generation. Eel migration was assumed to be triggered by a minimum river flow associated with a minimum discharge pulse, so that threshold values can be directly implemented as decision rules for turbine shutdown. To estimate relevant thresholds, a generic methodological framework was developed to generate alternative decision rules from data collected at hydropower plants, which can include telemetry surveys and estimates of eel abundance. A multiple-criteria decision analysis was then conducted to rank alternatives and to determine the best compromise between promoting silver eel escapement and limiting turbine shutdown duration. Graphic outputs can help stakeholders to understand the competitive interests between eel conservation and hydropower production, while visually identifying a range of consensual alternatives to support negotiations in the choice of operational thresholds. The method was illustrated for three river systems in Europe featured by distinct hydrological conditions and can be applied in other areas, providing that eel monitoring surveys and flow data are available.


Assuntos
Anguilla , Rios , Animais , Europa (Continente) , Hidrologia
3.
Sci Total Environ ; 714: 136838, 2020 Apr 20.
Artigo em Inglês | MEDLINE | ID: mdl-32018979

RESUMO

Microbiota inhabiting the intermittent streambeds mediates several in-stream processes that are essential for ecosystem function. Reduced stream discharge caused by the strengthened intermittency and increased duration of the dry phase is a spreading global response to changes in climate. Here, the impacts of a 5-month desiccation, one-week rewetting and punctual storms, which interrupted the dry period, were examined. The genomic composition of total (DNA) and active (RNA) diversity, and the community level physiological profiles (CLPP) were considered as proxies for functional diversity to describe both prokaryotes and eukaryotes inhabiting the surface and hyporheic streambeds. Comparisons between the genomic and potential functional responses helped to understand how and whether the microbial diversity was sensitive to the environmental conditions and resource acquisition, such as water stress and extracellular enzyme activities, respectively. RNA expression showed the strongest relationship with the environmental conditions and resource acquisition, being more responsive to changing conditions compared to DNA diversity, especially in the case of prokaryotes. The DNA results presumably reflected the legacy of the treatments because inactive, dormant, or dead cells were included, suggesting a slow microbial biomass turnover or responses of the microbial communities to changes mainly through physiological acclimation. On the other hand, microbial functional diversity was largely explained by resources acquisition, such as metrics of extracellular enzymes, and appeared vulnerable to the hydrological changes and duration of desiccation. The data highlight the need to improve the functional assessment of stream ecosystems with the application of complementary metrics to better describe the streambed microbial dynamics under dry-rewet stress.


Assuntos
Microbiota , Biomassa , Hidrologia , Rios
4.
J Environ Manage ; 260: 110107, 2020 Apr 15.
Artigo em Inglês | MEDLINE | ID: mdl-32090820

RESUMO

Sustainable reservoir-river management requires balancing complex trade-offs and decision-making to support both human water demands and ecological function. Current numerical simulation and optimization algorithms can guide reservoir-river operations for optimal hydropower production, irrigation, nutrient management, and municipal consumption, yet much less is known about optimization of associated ecosystems. This ten-year study demonstrates an ecosystem assessment approach that links the environmental processes to an ecosystem response in order to evaluate the impact of climatic forcing and reservoir operations on the aquatic ecosystems of a coupled headwater reservoir-river system. The approach uses a series of numerical, statistical, and empirical models to explore reservoir operational flexibility aimed at improving the environmental processes that support aquatic ecosystem function. The results illustrate that understanding the seasonal biogeochemical changes in reservoirs is critical for determining environmental flow releases and the ecological trajectory of both the reservoir and river systems. The coupled models show that reservoir management can improve the ecological function of complex aquatic ecosystems under certain climatic conditions. During dry hydrologic years, the high post-irrigation release can increase the downstream primary and macroinvertebrate production by 99% and 45% respectively. However, this flow release would reduce total fish biomass in the reservoir by 16%, providing management tradeoffs to the different ecosystems. Additionally, low post-irrigation flows during the winter season supports water temperature that can maintain ice cover in the downstream river for improved ecosystem function. The ecosystem assessment approach provides operational flexibility for large infrastructure, supports transparent decision-making by management agencies, and facilitates framing of environmental legislation.


Assuntos
Ecossistema , Rios , Animais , Ecologia , Monitoramento Ambiental , Humanos , Hidrologia , Estações do Ano
5.
Water Res ; 172: 115461, 2020 Apr 01.
Artigo em Inglês | MEDLINE | ID: mdl-31951946

RESUMO

Coastal lagoons deliver a wide range of valuable ecosystem goods and services. These ecosystems, that are often maintained by direct or indirect groundwater supplies, are collectively known as groundwater dependent ecosystems (GDEs). The importance of groundwater supplies is greatly exacerbated in coastal Mediterranean regions where the lack of surface water and the over-development of anthropogenic activities critically threaten the sustainability of coastal GDEs and associated ecosystem services. Yet, coastal GDEs do not benefit from a legal or managerial recognition to take into account their specificity. Particular attention should be paid to the characterization of environmental and ecological water requirements. The hydrogeological knowledge about the management and behavior of coastal aquifers and GDEs must be strengthened. These investigations must be supplemented by a stronger assessment of potential contaminations to develop local land-uses and human activities according to the groundwater vulnerability. The quantitative management of water resources must also be better supervised and/or more constrained in order to ensure the water needs necessary to maintain coastal GDEs. The transdisciplinary approach between hydrogeology, hydrology, social sciences and law is essential to fully understand the socio-economic and environmental complexity of coastal GDEs. Priority must now be given to the development of an appropriate definition of coastal GDEs, based on a consensus between scientists and lawyers. It is a necessary first step to develop and implement specific protective legislation and to define an appropriate management scale. The investment and collaboration of local water users, stakeholders and decision-makers need to be strengthened through actions to favor exchanges and discussions. All water resources in the coastal areas should be managed collectively and strategically, in order to maximize use efficiency, reduce water use conflicts and avoid over-exploitation. It is important to continue to raise public awareness of coastal aquifers at the regional level and to integrate their specificities into coastal zone management strategies and plans. In the global context of unprecedented anthropogenic pressures, hydro-food crises and climate change, environmental protection and preservation of coastal GDEs represents a major challenge for the sustainable socio-economic and environmental development of Mediterranean coastal zones.


Assuntos
Ecossistema , Água Subterrânea , Conservação dos Recursos Naturais , Humanos , Hidrologia , Recursos Hídricos
6.
Environ Monit Assess ; 192(2): 85, 2020 Jan 03.
Artigo em Inglês | MEDLINE | ID: mdl-31900661

RESUMO

While the influence of stream restoration on vertical and lateral hyporheic exchange has been documented, impacts on broader riparian zone hydrology have not been thoroughly investigated. We quantified riparian water table dynamics, hydraulic gradient, and groundwater flow paths and fluxes across a range of hydrologic conditions following natural channel design restoration (riparian regrading, in-channel cross-vane structure installation). Water table measurements were collected at least once per season for 2.5 years to capture water levels during baseflow conditions from networks of wells and piezometers at sites with different stream morphology (created riffle-cross-vane-scour pool complexes versus natural pools and riffles), restoration status (agricultural restored, unrestored, forested reference), and riparian characteristics (slope, soils, topography) in North Carolina, USA. The regraded riparian zone had higher near-stream water tables (< 0.5 m below ground surface) than the unrestored site. Riffle-cross-vane complexes induced a zone of low hydraulic gradient that spanned 30-40% of the riparian area, similar to groundwater dynamics near beaver dams. This effect persisted regardless of hydrologic condition (wet or dry) or scour pool status (functioning or filled-in). Riffles also promoted a lower near-stream hydraulic gradient at the forested site. Conversely, the influence of stream features on riparian groundwater was minimal at the unrestored site, where groundwater fluxes were controlled by hillslope inputs and riparian geomorphology. Overall, restoration enhanced stream-riparian zone hydrologic interaction beyond the immediate hyporheic zone. Our work stresses that cross-vanes, even when partially buried by sediments post-restoration, impact whole floodplain hydrology in a more significant way than shown by prior stream restoration studies.


Assuntos
Agricultura , Monitoramento Ambiental , Rios , Inundações , Água Subterrânea , Hidrologia , North Carolina , Estações do Ano , Solo , Água
7.
J Environ Manage ; 261: 109920, 2020 May 01.
Artigo em Inglês | MEDLINE | ID: mdl-31999613

RESUMO

Green roof can mitigate urban stormwater and improve environmental, economic, and social conditions. Various modeling approaches have been effectively employed to implement a green roof, but previous models employed simplifications to simulate water movement in green roof systems. To address this issue, we developed a new modeling tool (SWMM-H) by coupling the stormwater management and HYDRUS-1D models to improve simulations of hydrological processes. We selected green roof systems to evaluate the coupled model. Rainfall-runoff experiments were conducted for a pilot-scale green roof and urban subbasin. Soil moisture in the green roof and runoff volume in the subbasin were simulated more accurately by using SWMM-H instead of SWMM. The scenario analysis showed that SWMM-H selected sandy loam for controlling runoff whereas SWMM recommended sand. In conclusion, SWMM-H could be a useful tool for accurately understanding hydrological processes in green roofs.


Assuntos
Chuva , Movimentos da Água , Cor , Hidrologia , Solo
8.
Nature ; 577(7791): 473-474, 2020 01.
Artigo em Inglês | MEDLINE | ID: mdl-31969723
9.
J Environ Manage ; 255: 109853, 2020 Feb 01.
Artigo em Inglês | MEDLINE | ID: mdl-31760296

RESUMO

Dry detention basins (DDBs) are a type of stormwater control measure (SCM) designed to provide flood storage, peak discharge reduction, and some water quality improvement through sedimentation. DDBs are ubiquitous in the urban environment, but are expensive to maintain. In this study, two overgrown DDBs near Raleigh, NC, receiving highway runoff were monitored for up to one year to quantify their water quality and hydrologic performance. Both basins, B1 and B2, have not received vegetation maintenance since construction in 2007. Flow-weighted composite samples were collected during storm events and analyzed for nutrients (Total Phosphorus (TP), Ortho-phosphorus (OP), Ammonia-N (NH3), NO2-3-N (NOX), and Total Kjeldahl Nitrogen (TKN)), total suspended solids (TSS), and total Cd, Cu, Pb, and Zn. An annual water balance was also conducted to quantify runoff volume reduction. Despite low influent concentrations from the highway, significant removal efficiencies were found for all constituents except NH3 in B1. TP, OP, NOX, TSS, and Zn were reduced in B2. Both basins achieved greater than 41% volume reduction through soil infiltration and evapotranspiration, resulting in significant pollutant load reductions for all detected constituents, between 59% and 79% in B1 and 35% and 81% in B2. This study provides evidence that overgrown and unmaintained DDBs can reduce pollutant concentrations comparable to those reported for maintained DDBs, while reducing more volume than standard DDBs. Moreover, carbon sequestration likely increases while maintenance costs decrease.


Assuntos
Poluentes Químicos da Água , Qualidade da Água , Monitoramento Ambiental , Hidrologia , Nitrogênio , Fósforo , Chuva , Movimentos da Água
10.
Sci Total Environ ; 703: 135588, 2020 Feb 10.
Artigo em Inglês | MEDLINE | ID: mdl-31771846

RESUMO

Understanding catchment hydrological response to intensive land use/cover change (LUCC) and climate change provides a basis for taking effective measures for the future. Runoff is a critical indicator of catchment hydrological processes that reflects the combined effects of climate changes and local human activities. In this study, three main tributary sub-catchments underlain by soft sandstone in the Yellow River basin, China, were chosen to attribute runoff variations to climatic change and human activities through improving the Budyko elasticity model. The results suggested that: (1) annual runoff exhibited a significant decreasing trend during the past 30 years (1981-2016, p < 0.01),with an average decline rate of 1.07 mm a-1; (2) the precipitation elasticity of runoff (εP) and that of potential evapotranspiration (εEo) varied from 2.42 to 2.96 and from -1.96 to -1.42, respectively, indicating that runoff is more sensitive to changes in P than those in Eo in the context of climate change; (3) the attribution analysis demonstrated that, on average, vegetation change (mainly anthropogenic vegetation coverage increase) accounted for 92% of the decline in runoff whereas climate change (including precipitation and potential evapotranspiration variations and consequent vegetation change) accounted for the rest 8%.


Assuntos
Mudança Climática , Monitoramento Ambiental/métodos , China , Atividades Humanas , Humanos , Hidrologia , Rios , Movimentos da Água
11.
J Environ Manage ; 255: 109863, 2020 Feb 01.
Artigo em Inglês | MEDLINE | ID: mdl-31790867

RESUMO

Water and land resource management planning benefits greatly from accurate prediction and understanding of the spatial distribution of wetness. The topographic wetness index (TWI) was conceived to predict relative surface wetness, and thus hydrologic responsiveness, across a watershed based on the assumption that shallow slope-parallel flow is a major driver of the movement and distribution of soil water. The index has been extensively used in modeling of landscape characteristics responsive to wetness, and some studies have shown the TWI performs well in landscapes where interflow is a dominant process. However, groundwater flow dominates the hydrology of low-slope landscapes with high subsurface conductivities, and the TWI assumptions are not likely to perform well in such environments. For groundwater dominated systems, we propose a hybrid wetness index (Wetness Index based on Landscape position and Topography, WILT) that inversely weights the upslope contributing area by the distance to the nearest surface water feature and the depth to groundwater. When explicit depth to groundwater data are not available, height above and separation from surface water features can act as surrogates for proximity to groundwater. The resulting WILT map provides a more realistic spatial distribution of relative wetness across a low-slope Coastal Plain landscape as demonstrated by improved prediction of hydric soils, depth to groundwater, nitrogen and carbon concentrations in the A horizon of the soil profile, and sensitivity to DEM scale.


Assuntos
Água Subterrânea , Solo , Carbono , Monitoramento Ambiental , Hidrologia , Água
12.
Water Environ Res ; 92(2): 278-290, 2020 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-31544306

RESUMO

There are noteworthy problems in current strategies to calculate river water environmental capacity (WEC), including the generalization of tributaries and water intakes, which results in inaccurate calculation results of the WEC, and the difficulty in adapting to dynamic changes in demands and hydrological conditions in terms of practical application. To address these flaws, the subsection summation model (SSM) was built for river WEC calculation. The SSM increases the number of control sections according to drain outlets, water intakes, and tributaries and acquires the WEC of the functional area section by section. The Wei River was taken as the study area for verification and application of the SSM. Supported by a comprehensive integration platform, the WEC simulation system of the Wei River was constructed. The results show that the SSM enhances the accuracy of the WEC calculation, and the results are closer to the actual situation. The simulation system could obtain the WEC according to the demands and changes in the hydrological conditions, thus providing technical means for policymakers. PRACTITIONER POINTS: The subsection summation model provides a more accurate water environmental capacity (WEC) calculation method considering tributaries and water intakes avoiding generalization. The simulation system should be established to make the WEC calculation adapt to the demands or changes in the hydrological conditions. The model and system could supply the basis and technical means for decision-making.


Assuntos
Rios , Poluentes Químicos da Água , Monitoramento Ambiental , Água Doce , Hidrologia , Qualidade da Água
13.
Water Res ; 170: 115351, 2020 Mar 01.
Artigo em Inglês | MEDLINE | ID: mdl-31810033

RESUMO

Determination of the effects of cascade dams on benthic microbial ecosystem is essential for dam regulation and ecological function protection. However, no comprehensive investigation has yet shown the ecosystem-level responses of microbiota to dam impoundments. This study conducted DNA metabarcoding and microbial food web analysis for multiple species and their interrelationships along a cascade dam-affected river. The composition, distribution and diversity of bacteria, protozoans and metazoans were obviously different between river and reservoirs, mainly controlled by hydrological (P < 0.01) and nutrient parameters (P < 0.05). Those three groups make up a co-occurrence network, with most edges direct from higher to lower trophic levels or vice versa and more than 50% keystones participate in the food web, indicating the significant role of predator-prey relationships. Based on the microbial food web analysis, the predator biomass, especially at higher trophic levels, decreased by about 10% from the riverine to the lacustrine system. The structural equation model illustrates that both bottom-up forces (environmental factors particularly velocity and nutrient concentrations) and top-down forces (higher trophic levels) critically control microbial food web patterns (P < 0.05). As a result of dam impoundments, the lower velocity in the reservoirs has direct negative effects on trophic transfer efficiencies that may be further magnified by nutrient accumulation, probably leading to an increase of eutrophication and posing a risk to water quality. The results suggest the potential ecological risk in the reservoirs and highlight the need to consider from the perspective of ecosystem during the operation of cascade dams.


Assuntos
Ecossistema , Cadeia Alimentar , Biomassa , Hidrologia , Rios
14.
Sci Total Environ ; 704: 135268, 2020 Feb 20.
Artigo em Inglês | MEDLINE | ID: mdl-31810677

RESUMO

Streams are influenced by watershed-scale factors, such as climate, geology, topography, hydrology, and soils, which mostly vary naturally among sites, as well as human factors, agriculture and urban development. Thus, natural factors could complicate assessment of human disturbance. In the present study, we use structural equation modeling and data from the 2008-2009 United States National Rivers and Streams Assessment to quantify the relative importance of watershed-scale natural and human factors for in-stream conditions. We hypothesized that biological condition, represented using a diatom multimetric index (MMI), is directly affected by in-stream physicochemical environment, which in turn is regulated by natural and human factors. We evaluated this hypothesis at both national and ecoregion scales to understand how influences vary among regions. We found that direct influences of in-stream environment on diatom MMIs were greater than natural and human factors at the national scale and in all but one ecoregion. Meanwhile, in-stream environments were jointly explained by natural variations in precipitation, base flow index, hydrological stability, % volcanic rock, soil water table depth, and soil depth and by human factors measured as % crops, % other agriculture, and % urban land use. The explained variance of in-stream environment by natural and human factors ranged from 0.30 to 0.75, for which natural factors independently accounted for the largest proportion of explained variance at the national scale and in seven ecoregions. Covariation between natural and human factors accounted for a higher proportion of explained variance of in-stream environment than unique effects of human factors in most ecoregions. Ecoregions with relatively weak effects by human factors had relatively high levels of covariance, high levels of human disturbance, or small ranges in human disturbance. We conclude that accounting for effects of natural factors and their covariation with human factors will be important for accurate ecological assessments.


Assuntos
Monitoramento Ambiental , Rios/química , Poluição da Água/análise , Biodiversidade , Ecologia , Ecossistema , Humanos , Hidrologia , Estados Unidos
15.
Ground Water ; 58(1): 143-151, 2020 01.
Artigo em Inglês | MEDLINE | ID: mdl-31359409

RESUMO

Gravity Recovery and Climate Experiment (GRACE) satellite mission is ground-breaking information hotspot for the evaluation of groundwater storage. The present study aims at validating the sensitivity of GRACE data to groundwater storage variation within a basaltic aquifer system after its statistical downscaling on a regional scale. The basaltic aquifer system which covers 82.06% area of Maharashtra state in India, is selected as the study area. Five types of basaltic aquifer systems with varying groundwater storage capacities, based on hydrologic characteristics, have been identified within the study area. The spatial and seasonal trend analysis of observed in situ groundwater storage anomalies (ΔGWSano) computed from groundwater level data of 983 wells from the year 2002 to 2016, has been performed to analyze the variation in groundwater storages in the different basaltic aquifer system. The groundwater storage anomalies (ΔGWSDano) have been derived from GRACE Release 05 (RL05) after removing the soil moisture anomaly (ΔSMano) and canopy water storage anomaly (ΔCNOano) obtained from Global Land Data Assimilation System (GLDAS) land surface models (NOAH, MOSAIC, CLM and VIC). The artificial neural network technique has been used to downscale the GRACE and GLDAS data at a finer spatial resolution of 0.125°. The study shows that downscaled GRACE and GLDAS data at a finer spatial resolution is sensitive to seasonal groundwater storage variability in different basaltic aquifer systems and the regression coefficient R has been found satisfactory in the range of 0.696 to 0.818.


Assuntos
Água Subterrânea , Clima , Monitoramento Ambiental , Hidrologia , Índia
16.
Water Environ Res ; 92(1): 106-114, 2020 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-31344757

RESUMO

This study determines the exfiltration rates in six tree boxes with embedded sensors and analyzes their hydrologic performance for 2 years to quantify the effect of different parameters (i.e., water depth, temperature, and age) on the exfiltration rate. Each tree box is 1.5 m wide, 1.5 m long, and 1.8 m deep. A 46-cm-diameter shaft was drilled at the bottom of each tree box to reach the underlying permeable soil layer. The water level inside the shaft rose up to 500 cm. Exfiltration rate increased with water level and exfiltration rate in second year decreased significantly by 27%-37% compared with first year. Overall, in the second year, the decrease in geometric mean exfiltration rate was largest for moderate depths of the standing water inside the shaft, ranging between 100 and 130 cm from the bottom of the shaft. The exfiltration rate of the tree boxes was significantly larger for warmer season and significantly smaller for cooler season. The infiltration rate of the underlying soil is a controlling factor of the performance of tree box. PRACTITIONER POINTS: The study determines the exfiltration rates in six tree boxes and analyzes their performance over time. Exfiltration rate in second year decreased significantly by 27%-37% compared to first year. The exfiltration rate of the tree boxes was larger for warmer rain events and smaller for cooler rain events. Tree boxes with lower permeable underlying soil developed higher water level in the shaft.


Assuntos
Árvores , Movimentos da Água , Hidrologia , Chuva , Solo
17.
J Environ Manage ; 255: 109823, 2020 Feb 01.
Artigo em Inglês | MEDLINE | ID: mdl-31785458

RESUMO

Mismanagement of rangelands worldwide has accelerated processes of overland flow and soil erosion, resulting in extensive land degradation. Wherever self-restoration processes of degraded rangelands are hindered or negated, active recovery efforts, coupled with livestock pressure management, might be needed. The objective of this review paper is to provide land managers and environmental planners with applied and practical knowledge on advantages and disadvantages of the main methodologies and practices for runoff harvesting in rangelands. Preferably, restoration efforts should focus on forming low-footprint runoff harvesting systems on hillslopes which encompass the runoff's source area. These systems should imitate natural patchiness, strengthening source-sink relations, accelerating re-establishment of herbaceous and woody vegetation, maximizing the retaining of water on hillslopes, regulating hydrological connectivity, lessening soil erosion, and minimizing transmission of water to stream channels. The resulting lower-energy floods are expected to negate the need for massive check dams in channels. If flood dissipation in streams is still necessary, then high-to medium-porosity check dams, made of local materials, might be effective for lessening scour processes and sediment transport. Furthermore, in terms of environmental sustainability, a large number of pointed (e.g., branch bundles; brush or woody piles; micro-catchments) or low-to medium-footprint lineal means for regulating surface processes in hillslopes (e.g., stone terraces; contour furrows/trenches/ditches) and channels (e.g., log check dams; loose rock check dams; porous or semi-permeable rock check dams; gabions) are expected to be more cost-effective than a small number of massive means (e.g., contour bench terraces; earth bunds/dykes; concrete check dams). If runoff harvesting systems are properly designed, restoration processes over time are expected to generate geo-ecological feedbacks and recover eco-hydrological functioning, increasing pasture productivity and sustaining rangeland carrying capacity.


Assuntos
Solo , Água , Conservação dos Recursos Naturais , Hidrologia , Rios
18.
J Environ Manage ; 256: 109918, 2020 Feb 15.
Artigo em Inglês | MEDLINE | ID: mdl-31818739

RESUMO

Understanding the differences in the responses of river hydrology and water quality to climate and land use changes is particularly crucial for the development and management of water resources in the future. This study was carried out to assess the isolated and coupled effects of future climate change and land use change on the flow and nutrient load of the Xitiaoxi watershed in southeast China by applying the calibrated Hydrological Simulation Program Fortran model. Four representative concentration pathways released by the Intergovernmental Panel on Climate Change and two projected land use change scenarios were used to simulate future conditions. The results indicate that climate change would result in flow increased with an average variation of 25.2% in the future, and the increased flow would be mainly concentrated on the high flow part of the total flow duration curve. Climate change would also induce seasonal shifts to nutrient load. The effects of land use change showed that nutrient load was more sensitive than flow, made Orthophosphate load increase by 2.8%-154.7%, and flow increase by 7.2%-15.1%. The results for coupled climate and land use changes indicate that flow and nutrient load would be more affected by climate change than by land use change. Climate and land use changes may amplify or weaken each other's effects on flow and nutrient load, which suggests that both should be incorporated into hydrologic models when studying the future conditions. The results of this study can help decision-makers guide management practices that aim to minimize flow and nutrient load.


Assuntos
Modelos Teóricos , Movimentos da Água , China , Mudança Climática , Hidrologia , Nutrientes , Rios
19.
Sci Total Environ ; 706: 134489, 2020 Mar 01.
Artigo em Inglês | MEDLINE | ID: mdl-31862598

RESUMO

It is important to explore the influence of climate and planting structure change on runoff and nitrogen and phosphorus loss in watersheds, as well as to clarify the quantitative relationship between each influencing factor with runoff, nitrogen and phosphorus to formulate reasonable soil and water conservation measures and reduce non-point source pollution in the watershed. In this study, the Lizixi watershed of the Jialing River was analyzed using a Global Climate Model to generate precipitation and temperature change sequences and the distributed hydrological model SWAT was used to simulate changes in runoff and nitrogen and phosphorus loss processes in the watershed under different climate change scenarios and planting structure changes. The results indicate that the increase in runoff caused by climate change in the next decade will be accompanied by an increase in the loss of total nitrogen and total phosphorus. Planting sweet potato under historical meteorological conditions had the best effect on controlling nitrogen and phosphorus loss in the Lizixi watershed, while large losses of nitrogen and phosphorus were produced when planting wheat and corn. At the same time, there is a positive correlation between the loss of nitrogen and phosphorus and the amount of fertilizer applied. For every 10% increase in fertilizer application, the loss of nitrogen and phosphorus increased by 1% and 4%, respectively. The results presented herein will serve as a reference for regional land use management planning.


Assuntos
Clima , China , Hidrologia , Nitrogênio , Fósforo , Rios , Solo
20.
Sci Total Environ ; 699: 134302, 2020 Jan 10.
Artigo em Inglês | MEDLINE | ID: mdl-31522046

RESUMO

Quantifying the catchment water balance and the characterization of its water quality changes are effective tools for establishing the response of catchments to shifting land management practices. Here we assess long-term hydrological partitioning and stream water chemistry over a 30-year period in a rural mixed land use catchment in northern Germany undergoing riparian wetlands and widespread re-colonization by beavers (Castor fiber) along the river network. We used long-term spatially distributed stream discharge, groundwater levels and surface water quality data with a simple monthly water balance model, changes in the variability in discharge measurements, and statistical analysis of spatio-temporal changes in stream water quality to assess long-term changes. Water balance estimates indicated high proportions of evapotranspiration loss (~90% of total precipitation) and relatively low groundwater recharge (<5% of total precipitation) prior to riparian rehabilitation in 2000. Increasing groundwater levels from 2000 to 2017 and the relatively linear nature of the catchment storage - discharge relationship, indicate a gradual increase in groundwater recharge (buts still <10% of total precipitation). Wetland rehabilitation, greatly enhanced by increasing beaver populations, resulted in longer water transit times in the stream network, less linear storage-discharge relationship and a loss of daily stream variability, increased DOC concentrations, isotopic evaporative enrichment downstream, and moderated stream temperatures. There was limited long-term water quality improvements from wetland rehabilitation on either nitrate or total phosphorus concentrations, with unchanged seasonal summer and winter peak concentrations for phosphorus and nitrate, respectively. This likely reflects the long-term legacy of fertilizer use on nutrient reservoirs in the catchment's soils, aquifers, and stream network. These long-term changes in hydrology and stream chemistry resulting from riparian rehabilitation and changes in agricultural management practices provide invaluable insights into catchment functioning and an evidence base for future planning in relation to long-term climatic changes.


Assuntos
Monitoramento Ambiental , Roedores , Áreas Alagadas , Agricultura , Animais , Recuperação e Remediação Ambiental , Alemanha , Água Subterrânea , Hidrologia , Nitratos , Nitrogênio , Fósforo , Rios , Solo , Água , Movimentos da Água , Qualidade da Água
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