Wetlands, one of the most productive systems in the biosphere are a unique ecosystem. They occur in landscapes that favor the ponding or slow runoff of surface water, discharge of ground water, or both. Wetlands are n...Wetlands, one of the most productive systems in the biosphere are a unique ecosystem. They occur in landscapes that favor the ponding or slow runoff of surface water, discharge of ground water, or both. Wetlands are not only important for maintaining plant and animal diversity, but also for balancing global carbon budget via sequestrating or releasing CO2 from/into atmosphere depending on their management. Therefore, it is imperative to understand how wetlands form and function, then we can better manage, utilize, and protect these unique ecosystems. Hydrie soils,hydrophytic vegetation, and wetland hydrology are the three main parameters of wetlands. These parameters are interrelated with each other which jointly influence the development and functions of wetland ecosystems. The objective of this paper was to report the current understanding of wetlands and provide future research directions. The paper will first focus on aspects of hydrology research in wetlands, and then shift to soil hydrosequence and wetland vegetation to better understand processes, structure, and function of wetlands, and conclude with some possible future research directions.展开更多
Although forests play important roles in the hydrological cycle,there is little information that relates the water retention capacity of litter in areas under passive restoration,especially in Cerrado savannas.This st...Although forests play important roles in the hydrological cycle,there is little information that relates the water retention capacity of litter in areas under passive restoration,especially in Cerrado savannas.This study relates litter levels to water holding capacity and effective water retention among forest fragments under different passive restoration stages:46,11,and 8 years to better understand litter hydrological functions in the Cerrado.Water retention capacity and effective water retention capacity of litters(unstructured materials,branches and leaves)in the field were monitored on a monthly basis.Total litter accumulation at 46 years was significantly higher than that of the other succession stages.Unstructured litter mass was significantly higher than that of leaves and branches.The 46-year stage had the highest water holding capacity in the leaf fraction,followed by unstructured material and branches.Although the water holding capacity was lower in the oldest resto-ration,this site showed the highest efficiency under field conditions.The process was quickly reestablished,as the 11-year restoration showed results closer to that for the 46-year stage in comparison to the area at 8 years.Thus,passive restoration plays a key role in soil water mainte-nance due to the influence of litter in Cerrado savannas.Deforestation and the imminent need of restoring degraded sites,highlight the need for further studies focused on bet-ter understanding of the process of forest restoration and its temporal effect on soil water recovery dynamics.展开更多
The hydrology of the Little Ruaha River which is a major catchment of the Ihemi Cluster in the Southern Agricultural Growth Corridor of Tanzania (SA-GCOT) has been studied. The study focused on the hydrological assess...The hydrology of the Little Ruaha River which is a major catchment of the Ihemi Cluster in the Southern Agricultural Growth Corridor of Tanzania (SA-GCOT) has been studied. The study focused on the hydrological assessment through analysis of the available data and developing a model that could be used for assessing impacts of environmental change. Pressures on land and water resources in the watershed are increasing mainly as a result of human activities, and understanding the hydrological regime is deemed necessary. In this study, modeling was conducted using the Soil and Water Assessment Tool (SWAT) in which meteorological and streamflow data were used in the simulation, calibration and evaluation. Calibration and evaluation was done at three gauging stations and the results were deemed plausible with NSE ranging between 0.64 and 0.80 for the two stages. The simulated flows were used for gap filling the missing data and generation of complete daily time series of streamflow at three gauging stations of Makalala, Ihimbu and Mawande. Results of statistical trends and flow duration curves, revealed decline in magnitudes of seasonal and annual flows indicating that streamflows are changing with time and may have implications on envisioned development and the water dependent ecosystems.展开更多
From the viewpoint of system approach, karst drainage basin is the ideel unit in studying structure and evolutional regularity of karst hydrogeomorpholegical system, It is because the drainage basin is a natural unit ...From the viewpoint of system approach, karst drainage basin is the ideel unit in studying structure and evolutional regularity of karst hydrogeomorpholegical system, It is because the drainage basin is a natural unit with clear border which can reflect the internal structure and outside environment of the system and their interrelation. Through the research on karst hydrology and geomorphology, four basic characteristics of the karst drainage basin have been identified.展开更多
Urban development generally leads to an increase in impervious cover resulting in a greater volume of surface runoff following storm activity. However, the type of urban development in place strongly controls the degr...Urban development generally leads to an increase in impervious cover resulting in a greater volume of surface runoff following storm activity. However, the type of urban development in place strongly controls the degree of impervious cover generated. Traditional neighborhood designs focus on a medium-to-low urban density spread over larger areas, while new urbanist neighborhood designs incorporate more diversity by increasing urban density across smaller areas. The purpose of this study is to model and compare the potential surface runoff for two urban neighborhoods in Austin, Texas-Circle C Ranch, a traditional neighborhood design, and Mueller, a new urbanist development for a 10-year 24-hour storm scenario. Potential surface runoff was calculated by layering various geospatial datasets representing the physical characteristics of both study sites within the Watershed Modeling System (WMS) to configure the HEC-HMS runoff model. Results initially imply that the higher density new urbanist neighborhood significantly increases total and peak storm runoff compared to the traditional neighborhood. However, a greater number of residential units are available at Mueller over the same area as Circle C Ranch. When taking this into account the increased potential surface runoff is negated at the new urbanist site. Although new urbanist neighborhoods will usually contain more residential units than traditional developments when compared at the same scale, the higher urban density associated with these neighborhoods demand the development of more effective stormwater retention systems to cope with a potential increase in surface runoff.展开更多
In the second term of 2019-2020,colleges and universities have launched a network teaching mode due to"novel coronavirus pneumonia"epidemic.The courses in colleges and universities are diversified due to the...In the second term of 2019-2020,colleges and universities have launched a network teaching mode due to"novel coronavirus pneumonia"epidemic.The courses in colleges and universities are diversified due to the difference of majors.For the Environmental Hydrology,students often show different degrees of interest in learning this course.Of course,each student s own situation is different.Teachers should consider a variety of factors in online classroom,pay more attention to students performance,and give appropriate guidance in time.展开更多
Crack orientations are an important soil physical property that affects water flow, particularly in vertic soils. However, the spatial and temporal variability of crack orientations across different land uses and gilg...Crack orientations are an important soil physical property that affects water flow, particularly in vertic soils. However, the spatial and temporal variability of crack orientations across different land uses and gilgai features is not well-documented and addressed in hydrology models. Thus;there is a need to quantify crack orientations for different land uses and to incorporate their spatial and temporal dynamics into hydrological models. Our objectives were to document the spatial variability of cracks orientations across two land uses and to demonstrate the potential importance of crack orientation related to the hydrology of Vertisols. The exploratory field measurements of the spatial distribution of crack orientations across two Vertisol catenae of two land uses and gilgai features are presented. The field survey showed the complexity of crack geometry in a field, the potential impact of crack orientation on Vertisol hydrology and the challenges associated with measurement of crack orientations.展开更多
The performance on prediction by mathematical models which represent the conceived image of a system such as hydrology is oftentimes represented through calibration and verification processes. Oftentimes a best fit be...The performance on prediction by mathematical models which represent the conceived image of a system such as hydrology is oftentimes represented through calibration and verification processes. Oftentimes a best fit between observed and predicted flows is obtained through correlation coefficient (R2) and the Nash Sutcliffe model efficiency (NSE) by minimizing the average Root Mean Square Error (RMSE) of the observed versus simulated flows. However, these days, a new paradigm is emerging wherein accounting for the flow variability for the protection of freshwater biodiversity and maintenance of goods and services that rivers provide is paramount. Therefore, from an ecohydrology perspective, it is not clear if the existing method of model calibration meets the needs of the riverine ecosystem at its best. Thus, this study investigates and proposes a methodology using entropy theory to gage the calibration of Soil and Water Assessment Tool (SWAT) from an ecohydrology perspective characterized by the natural flow-regime paradigm: Indicators of Hydrologic Alteration.展开更多
This paper examines the geomorphology and hydrology of the Benin Region, Edo State, Nigeria. The major landform features and processes of the region are highlighted. This region is a strategic and significant landscap...This paper examines the geomorphology and hydrology of the Benin Region, Edo State, Nigeria. The major landform features and processes of the region are highlighted. This region is a strategic and significant landscape in Nigeria. Information was gathered on the various aspects of the landscape, including the Geology, Physiography (Relief) and Geomorphology, Geomorphic processes, Weathering, Drainage processes, Landforms, Surface Water Hydrology and Water Resources. The Benin Region is underlained by sedimentary formation of the South Sedimentary Basin. The geology is generally marked by top reddish earth, composed of ferruginized or literalized clay sand. Geologically, the Benin Region comprises of 1) the Benin formation;2) alluvium;3) drift/top soil and 4) Azagba-Ogwashi (Asuba-Ogwashi) formation. Several parts of the region are surrounded by the Benin historical moats. The region has been described as a tilled plain in the south western direction. The local relief of the region is 91 m. Boreholes records in the Benin Region show evidence of deep chemical weathering overtime. Soil profile reveals that the region is composed mainly of reddish brown sandy laterite. Intermittent layers of porous sands of sandy clays may reach a large depth as found in the borehole drilled in the region. These are products of deep chemical decay of the original parent rock materials. Three river systems drain the Benin Region. They are the Ikpoba River, the Ogba River and Owigie-Ogbovben River systems. The mean annual discharge of Ikpoba River for 1982-1983 and 1993-2002 was 1411 mm/yr, which was 1.019 × 10<sup>9</sup> m<sup>3</sup> with a mean annual baseflow of 1256.23 mm (0. 907 × 109 m<sup>3</sup>). This constitutes 87.65% of the total flow. It has a mean annual surface runoff of 225.18 mm (0.112 × 10<sup>9</sup> m<sup>3</sup>) or 24.4 % of the total discharge. The water resources of the region include surface water and underground water.展开更多
The use of isotope techniques and methods in catchment hydrology in the last 50 years has generated two major types of progress: (1) Assessment of the temporal variations of the major stocks and flows of water in catc...The use of isotope techniques and methods in catchment hydrology in the last 50 years has generated two major types of progress: (1) Assessment of the temporal variations of the major stocks and flows of water in catchments, from which the estimation of wa-ter residence times is introduced in this paper. (2) Assessment of catchment hydrologic processes, in which the interactions be-tween different waters, hydrographical separation, and bio-geochemical process are described by using isotopes tracers. Future progress on isotope techniques and methods in hydrology is toward the understanding of the hydrological process in large river basins. Much potential also waits realization in terms of how isotope information may be used to calibrate and test distributed rainfall-runoff models and regarding aid in the quantification of sustainable water resources management.展开更多
Seagull Lake is an unusual saline lake,having a marine spring connected to a large continental ecosystem.With climate change the balance between marine,meteoric and groundwater inputs to,and evaporitic and
Climate change is one of the greatest issues for human society. The objective of this study is to assess the impacts of future climate change on seasonal average discharge and monthly water budget in a small headwater...Climate change is one of the greatest issues for human society. The objective of this study is to assess the impacts of future climate change on seasonal average discharge and monthly water budget in a small headwater catchment, located on the Grande River basin, in Minas Gerais, Brazil. The assessment is carried out using the hydrology model, DHSVM. The atmospheric forcing to drive the Distributed Hydrology-Soil-Vegetation Model (DHSVM) is derived from the downscaling of the HadGEM2-ES projections by the Eta Regional Climate Model, at 5-km high resolution. The projections assume the RCP4.5 and RCP8.5 IPCC AR5 emission scenarios. Baseline period was taken between 1961 and 1990. The projections are assessed in three time slices (2011-2040, 2041-2070 and 2071-2099). The climate change is assessed in time slices of 30 years and in comparison against the baseline period to evaluate the hydrological changes in the catchment. The results showed differences in the hydrological behavior between the emission scenarios and though time slices. Reductions in the magnitude of the seasonal average discharge and monthly water budget may alter the water availability. Under the RCP4.5 scenario, results show greater reductions in the water availability in the first time slice, whereas under RCP8.5 scenario greater reductions are indicated in the third time slice.展开更多
The use of probability theory and mathematical statistics in hydrology has begun very late. Nevertheless, lately, thestatistical methods in hydrology engineering and in economy aspects as well, have been found to be o...The use of probability theory and mathematical statistics in hydrology has begun very late. Nevertheless, lately, thestatistical methods in hydrology engineering and in economy aspects as well, have been found to be of vital importance, bysuccessfully solving many problems considering the hydrological laws and the quantity evaluation of the many characteristics ofdifferent hydrological regimes. The use of the statistical methods should not be used formally, because it can lead to wrongconclusions, which would lead to bad dimensioning of the hydro-technical objects. The solving of many hydrological problems withstatistical methods, is made possible with the aid of computational calculations. Considering the facts mentioned above, we havemade on simple program, in excel, for achieving probabilistic results for different time frequencies, using the logarithmic functionstaken by four different authors. This program has been used for analyzing the river bed and bed load transport of the Sitnica rivershed, in the territory of Kosova.展开更多
There is an increasing demand from the hydrological community to improve the monitoring and modeling of hydrological processes using remote sensing technologies.However,this task has been severely limited by the coars...There is an increasing demand from the hydrological community to improve the monitoring and modeling of hydrological processes using remote sensing technologies.However,this task has been severely limited by the coarse resolution of previous remote sensing observations.In recent years,along with the increased availability of high-resolution modeling in hydrology,the advent of high-resolution temporal dynamic satellite observations has been providing unprecedented new opportunities to address new applications and challenges in hydrology.展开更多
1.Introduction Global Change Hydrology(GCH)is an emerging interdisciplinary field that links global change research and hydrology.GCH integrates hydrology,climatology,and geography to study the interactions between th...1.Introduction Global Change Hydrology(GCH)is an emerging interdisciplinary field that links global change research and hydrology.GCH integrates hydrology,climatology,and geography to study the interactions between the terrestrial water cycle and global change across various time and space scales.The main objective of GCH is to understand the natural and anthropogenic causes of the changing terrestrial water cycle and the associated influences and feedbacks in the Earth system.展开更多
Our understanding of both the role and impact of Arctic environmental changes under the current global warming climate is rather limited despite efforts of improved monitoring and wider assessment through remote sensi...Our understanding of both the role and impact of Arctic environmental changes under the current global warming climate is rather limited despite efforts of improved monitoring and wider assessment through remote sensing technology. Changes of Arctic ecosystems under early Paleogene warming climate provide an analogue to evaluate long-term responses of Arctic environmental alteration to global warming. This study reviews Arctic terrestrial ecosystems and their transformation under marked change of hydrological conditions during the warmest period in early Cenozoic, the Paleocene and Eocene. We describe a new approach to quantitatively reconstruct high latitudinal paleohydrology using compound-specific hydrogen isotope analysis which applies empirically derived genus-specific hydrogen isotope fractionations to in situ biomolecules from fossil plants. We propose a moisture recycling model at the Arctic to explain the reconstructed hydrogen isotope signals of ancient high latitude precipitation during early Paleogene, which bears implications to the likely change of modern Arctic ecosystems under the projected accelerated global warming.展开更多
The development of isotope hydrology in China is briefly reviewed. It includes oxygen and hydrogen isotopes of precipitation, application of isotope hydrological methodologies in solving water resources problems, isot...The development of isotope hydrology in China is briefly reviewed. It includes oxygen and hydrogen isotopes of precipitation, application of isotope hydrological methodologies in solving water resources problems, isotope hydrological studies on brines and salt lake waters, as well as isotope hydrological investigations of thermal waters. The review focuses on isotope hydrology in China during the last two decades.展开更多
Over 600 chloride-bearing deposits(chlorides) have been identified on the southern highlands of Mars. These chlorides have critical implications for hydrology and astrobiology: they are indicators of an evaporating su...Over 600 chloride-bearing deposits(chlorides) have been identified on the southern highlands of Mars. These chlorides have critical implications for hydrology and astrobiology: they are indicators of an evaporating super saturated solution, and they could have provided habitat environments for halophilic microorganisms and preserved organic matter. One of the prominent geomorphology characteristics of these chloridebearing regions is the polygonal features within them. The origin of these polygonal features is still in debate. In this study, we have surveyed 153 locations of chlorides using 441 high resolution imaging science experiment(Hi RISE) images to characterize the geomorphology of polygonal features. We identified 3 types of polygonal features of distinct geomorphologic characteristics: fractures, raised ridges, and transitional polygons between fractures and raised ridges. We evaluate previously proposed hypotheses of the formation of the polygonal features, and suggest that the 3 types of polygonal features are indicators of different stages of salt crust formation. Salt crust is usually formed through multiple groundwater activities, and it often occurs in playa environment on Earth. The unique hydrological and astrobiological implications of the chlorides with polygonal features make these deposits of high priority for future landed on and/or sample return exploration missions of Mars.展开更多
文摘Wetlands, one of the most productive systems in the biosphere are a unique ecosystem. They occur in landscapes that favor the ponding or slow runoff of surface water, discharge of ground water, or both. Wetlands are not only important for maintaining plant and animal diversity, but also for balancing global carbon budget via sequestrating or releasing CO2 from/into atmosphere depending on their management. Therefore, it is imperative to understand how wetlands form and function, then we can better manage, utilize, and protect these unique ecosystems. Hydrie soils,hydrophytic vegetation, and wetland hydrology are the three main parameters of wetlands. These parameters are interrelated with each other which jointly influence the development and functions of wetland ecosystems. The objective of this paper was to report the current understanding of wetlands and provide future research directions. The paper will first focus on aspects of hydrology research in wetlands, and then shift to soil hydrosequence and wetland vegetation to better understand processes, structure, and function of wetlands, and conclude with some possible future research directions.
基金This work is supported by the International Paper Co.from Brazil(Process 23112.000670/2015-59)by Brazilian National Council for Scientific and Technological Development(CNPq)in part by the Coordenação de Aperfeiçoamento de Pessoal de Nível Superior-Brasil(CAPES)-Finance Code 001.
文摘Although forests play important roles in the hydrological cycle,there is little information that relates the water retention capacity of litter in areas under passive restoration,especially in Cerrado savannas.This study relates litter levels to water holding capacity and effective water retention among forest fragments under different passive restoration stages:46,11,and 8 years to better understand litter hydrological functions in the Cerrado.Water retention capacity and effective water retention capacity of litters(unstructured materials,branches and leaves)in the field were monitored on a monthly basis.Total litter accumulation at 46 years was significantly higher than that of the other succession stages.Unstructured litter mass was significantly higher than that of leaves and branches.The 46-year stage had the highest water holding capacity in the leaf fraction,followed by unstructured material and branches.Although the water holding capacity was lower in the oldest resto-ration,this site showed the highest efficiency under field conditions.The process was quickly reestablished,as the 11-year restoration showed results closer to that for the 46-year stage in comparison to the area at 8 years.Thus,passive restoration plays a key role in soil water mainte-nance due to the influence of litter in Cerrado savannas.Deforestation and the imminent need of restoring degraded sites,highlight the need for further studies focused on bet-ter understanding of the process of forest restoration and its temporal effect on soil water recovery dynamics.
文摘The hydrology of the Little Ruaha River which is a major catchment of the Ihemi Cluster in the Southern Agricultural Growth Corridor of Tanzania (SA-GCOT) has been studied. The study focused on the hydrological assessment through analysis of the available data and developing a model that could be used for assessing impacts of environmental change. Pressures on land and water resources in the watershed are increasing mainly as a result of human activities, and understanding the hydrological regime is deemed necessary. In this study, modeling was conducted using the Soil and Water Assessment Tool (SWAT) in which meteorological and streamflow data were used in the simulation, calibration and evaluation. Calibration and evaluation was done at three gauging stations and the results were deemed plausible with NSE ranging between 0.64 and 0.80 for the two stages. The simulated flows were used for gap filling the missing data and generation of complete daily time series of streamflow at three gauging stations of Makalala, Ihimbu and Mawande. Results of statistical trends and flow duration curves, revealed decline in magnitudes of seasonal and annual flows indicating that streamflows are changing with time and may have implications on envisioned development and the water dependent ecosystems.
文摘From the viewpoint of system approach, karst drainage basin is the ideel unit in studying structure and evolutional regularity of karst hydrogeomorpholegical system, It is because the drainage basin is a natural unit with clear border which can reflect the internal structure and outside environment of the system and their interrelation. Through the research on karst hydrology and geomorphology, four basic characteristics of the karst drainage basin have been identified.
文摘Urban development generally leads to an increase in impervious cover resulting in a greater volume of surface runoff following storm activity. However, the type of urban development in place strongly controls the degree of impervious cover generated. Traditional neighborhood designs focus on a medium-to-low urban density spread over larger areas, while new urbanist neighborhood designs incorporate more diversity by increasing urban density across smaller areas. The purpose of this study is to model and compare the potential surface runoff for two urban neighborhoods in Austin, Texas-Circle C Ranch, a traditional neighborhood design, and Mueller, a new urbanist development for a 10-year 24-hour storm scenario. Potential surface runoff was calculated by layering various geospatial datasets representing the physical characteristics of both study sites within the Watershed Modeling System (WMS) to configure the HEC-HMS runoff model. Results initially imply that the higher density new urbanist neighborhood significantly increases total and peak storm runoff compared to the traditional neighborhood. However, a greater number of residential units are available at Mueller over the same area as Circle C Ranch. When taking this into account the increased potential surface runoff is negated at the new urbanist site. Although new urbanist neighborhoods will usually contain more residential units than traditional developments when compared at the same scale, the higher urban density associated with these neighborhoods demand the development of more effective stormwater retention systems to cope with a potential increase in surface runoff.
基金Supported by the Project of Education Department of Guangdong Province:"Foshan University-Chinese Academy of Sciences Innovation and Entrepreneurship Base for College Students in Dinghushan Nature Reserve""Scientific Research Project and Achievements Cultivation-Education Reform Cultivation Project of Guangdong High-level Universities of Science and Technology"of Foshan University.
文摘In the second term of 2019-2020,colleges and universities have launched a network teaching mode due to"novel coronavirus pneumonia"epidemic.The courses in colleges and universities are diversified due to the difference of majors.For the Environmental Hydrology,students often show different degrees of interest in learning this course.Of course,each student s own situation is different.Teachers should consider a variety of factors in online classroom,pay more attention to students performance,and give appropriate guidance in time.
文摘Crack orientations are an important soil physical property that affects water flow, particularly in vertic soils. However, the spatial and temporal variability of crack orientations across different land uses and gilgai features is not well-documented and addressed in hydrology models. Thus;there is a need to quantify crack orientations for different land uses and to incorporate their spatial and temporal dynamics into hydrological models. Our objectives were to document the spatial variability of cracks orientations across two land uses and to demonstrate the potential importance of crack orientation related to the hydrology of Vertisols. The exploratory field measurements of the spatial distribution of crack orientations across two Vertisol catenae of two land uses and gilgai features are presented. The field survey showed the complexity of crack geometry in a field, the potential impact of crack orientation on Vertisol hydrology and the challenges associated with measurement of crack orientations.
文摘The performance on prediction by mathematical models which represent the conceived image of a system such as hydrology is oftentimes represented through calibration and verification processes. Oftentimes a best fit between observed and predicted flows is obtained through correlation coefficient (R2) and the Nash Sutcliffe model efficiency (NSE) by minimizing the average Root Mean Square Error (RMSE) of the observed versus simulated flows. However, these days, a new paradigm is emerging wherein accounting for the flow variability for the protection of freshwater biodiversity and maintenance of goods and services that rivers provide is paramount. Therefore, from an ecohydrology perspective, it is not clear if the existing method of model calibration meets the needs of the riverine ecosystem at its best. Thus, this study investigates and proposes a methodology using entropy theory to gage the calibration of Soil and Water Assessment Tool (SWAT) from an ecohydrology perspective characterized by the natural flow-regime paradigm: Indicators of Hydrologic Alteration.
文摘This paper examines the geomorphology and hydrology of the Benin Region, Edo State, Nigeria. The major landform features and processes of the region are highlighted. This region is a strategic and significant landscape in Nigeria. Information was gathered on the various aspects of the landscape, including the Geology, Physiography (Relief) and Geomorphology, Geomorphic processes, Weathering, Drainage processes, Landforms, Surface Water Hydrology and Water Resources. The Benin Region is underlained by sedimentary formation of the South Sedimentary Basin. The geology is generally marked by top reddish earth, composed of ferruginized or literalized clay sand. Geologically, the Benin Region comprises of 1) the Benin formation;2) alluvium;3) drift/top soil and 4) Azagba-Ogwashi (Asuba-Ogwashi) formation. Several parts of the region are surrounded by the Benin historical moats. The region has been described as a tilled plain in the south western direction. The local relief of the region is 91 m. Boreholes records in the Benin Region show evidence of deep chemical weathering overtime. Soil profile reveals that the region is composed mainly of reddish brown sandy laterite. Intermittent layers of porous sands of sandy clays may reach a large depth as found in the borehole drilled in the region. These are products of deep chemical decay of the original parent rock materials. Three river systems drain the Benin Region. They are the Ikpoba River, the Ogba River and Owigie-Ogbovben River systems. The mean annual discharge of Ikpoba River for 1982-1983 and 1993-2002 was 1411 mm/yr, which was 1.019 × 10<sup>9</sup> m<sup>3</sup> with a mean annual baseflow of 1256.23 mm (0. 907 × 109 m<sup>3</sup>). This constitutes 87.65% of the total flow. It has a mean annual surface runoff of 225.18 mm (0.112 × 10<sup>9</sup> m<sup>3</sup>) or 24.4 % of the total discharge. The water resources of the region include surface water and underground water.
基金conducted with in the Nation Basic Research Program of China (973 Program, Research No. 2007CB411502)project "Matter fluxes in Inner Mongo-lia as influenced by stocking rate (MAGIM)" funded by the German Science Foundation (DFG) (Research Unit 536)
文摘The use of isotope techniques and methods in catchment hydrology in the last 50 years has generated two major types of progress: (1) Assessment of the temporal variations of the major stocks and flows of water in catchments, from which the estimation of wa-ter residence times is introduced in this paper. (2) Assessment of catchment hydrologic processes, in which the interactions be-tween different waters, hydrographical separation, and bio-geochemical process are described by using isotopes tracers. Future progress on isotope techniques and methods in hydrology is toward the understanding of the hydrological process in large river basins. Much potential also waits realization in terms of how isotope information may be used to calibrate and test distributed rainfall-runoff models and regarding aid in the quantification of sustainable water resources management.
基金Financial assistance for the researchers to undertake the initial fieldwork in 2012 was provided by the Friends of Streaky Bay Parks as a Caring for our Country grantThe Royal Society of South Australia provided a research grant to assist with the continuation of the work in 2013
文摘Seagull Lake is an unusual saline lake,having a marine spring connected to a large continental ecosystem.With climate change the balance between marine,meteoric and groundwater inputs to,and evaporitic and
文摘Climate change is one of the greatest issues for human society. The objective of this study is to assess the impacts of future climate change on seasonal average discharge and monthly water budget in a small headwater catchment, located on the Grande River basin, in Minas Gerais, Brazil. The assessment is carried out using the hydrology model, DHSVM. The atmospheric forcing to drive the Distributed Hydrology-Soil-Vegetation Model (DHSVM) is derived from the downscaling of the HadGEM2-ES projections by the Eta Regional Climate Model, at 5-km high resolution. The projections assume the RCP4.5 and RCP8.5 IPCC AR5 emission scenarios. Baseline period was taken between 1961 and 1990. The projections are assessed in three time slices (2011-2040, 2041-2070 and 2071-2099). The climate change is assessed in time slices of 30 years and in comparison against the baseline period to evaluate the hydrological changes in the catchment. The results showed differences in the hydrological behavior between the emission scenarios and though time slices. Reductions in the magnitude of the seasonal average discharge and monthly water budget may alter the water availability. Under the RCP4.5 scenario, results show greater reductions in the water availability in the first time slice, whereas under RCP8.5 scenario greater reductions are indicated in the third time slice.
文摘The use of probability theory and mathematical statistics in hydrology has begun very late. Nevertheless, lately, thestatistical methods in hydrology engineering and in economy aspects as well, have been found to be of vital importance, bysuccessfully solving many problems considering the hydrological laws and the quantity evaluation of the many characteristics ofdifferent hydrological regimes. The use of the statistical methods should not be used formally, because it can lead to wrongconclusions, which would lead to bad dimensioning of the hydro-technical objects. The solving of many hydrological problems withstatistical methods, is made possible with the aid of computational calculations. Considering the facts mentioned above, we havemade on simple program, in excel, for achieving probabilistic results for different time frequencies, using the logarithmic functionstaken by four different authors. This program has been used for analyzing the river bed and bed load transport of the Sitnica rivershed, in the territory of Kosova.
基金support of the ESA projects DTE Hydrology(Contract no.ESA 4000129870/20/I-NB-CCN N.1)National Natural Science Foundation of China(No.42222109)+1 种基金DTE Hydrology Evolution(Contract no.ESA 4000136272/21/I-EF-CCN N.1)4D MED Hydrology(Contract no.ESA 4000136272/21/I-EF),and Irrigation+(Contract no.ESA 4000129870/20/I-NB).
文摘There is an increasing demand from the hydrological community to improve the monitoring and modeling of hydrological processes using remote sensing technologies.However,this task has been severely limited by the coarse resolution of previous remote sensing observations.In recent years,along with the increased availability of high-resolution modeling in hydrology,the advent of high-resolution temporal dynamic satellite observations has been providing unprecedented new opportunities to address new applications and challenges in hydrology.
基金supported by the National Natural Science Foundation of China (Grant Nos. 41425002, 41730645 & 41790424)
文摘1.Introduction Global Change Hydrology(GCH)is an emerging interdisciplinary field that links global change research and hydrology.GCH integrates hydrology,climatology,and geography to study the interactions between the terrestrial water cycle and global change across various time and space scales.The main objective of GCH is to understand the natural and anthropogenic causes of the changing terrestrial water cycle and the associated influences and feedbacks in the Earth system.
基金supported by CAS/SAFEA International Partnership Program for Creative Research Teams, the Pilot Project of Knowledge Innovation of CAS (Grant No. KZCX2-YW-105)the National Basic Research Program of China (Grant No. 2006CB806400)+2 种基金the National Natural Science Foun-dation of China (Grant Nos. 40402002, 40872011)the American Chemi-cal Society Petroleum Research Funds, NASA RI Space GrantBryant University Summer Research Funds.
文摘Our understanding of both the role and impact of Arctic environmental changes under the current global warming climate is rather limited despite efforts of improved monitoring and wider assessment through remote sensing technology. Changes of Arctic ecosystems under early Paleogene warming climate provide an analogue to evaluate long-term responses of Arctic environmental alteration to global warming. This study reviews Arctic terrestrial ecosystems and their transformation under marked change of hydrological conditions during the warmest period in early Cenozoic, the Paleocene and Eocene. We describe a new approach to quantitatively reconstruct high latitudinal paleohydrology using compound-specific hydrogen isotope analysis which applies empirically derived genus-specific hydrogen isotope fractionations to in situ biomolecules from fossil plants. We propose a moisture recycling model at the Arctic to explain the reconstructed hydrogen isotope signals of ancient high latitude precipitation during early Paleogene, which bears implications to the likely change of modern Arctic ecosystems under the projected accelerated global warming.
基金This paper is supported by State Key Project on Basic Research (Project number: 1999075500) Intelligence Innovation Research Project of Chinese Academy of Sciences (No. KZCX1-07).
文摘The development of isotope hydrology in China is briefly reviewed. It includes oxygen and hydrogen isotopes of precipitation, application of isotope hydrological methodologies in solving water resources problems, isotope hydrological studies on brines and salt lake waters, as well as isotope hydrological investigations of thermal waters. The review focuses on isotope hydrology in China during the last two decades.
基金supported by the National Scientific Foundation of China(Nos.41403052,41773061,41830214)the Fundamental Research Funds for the Central Universities,China University of Geosciences(Wuhan)(Nos.CUGL160402,CUG2017G02)+1 种基金the Lunar and Planetary Science Laboratory,Macao University of Science and Technology Partner Laboratory of Key Laboratory of Lunar and Deep Space Exploration,Chinese Academy of Sciences(Nos.039/2013/A2,121/2017/A3)supported by the National Training Program of Innovation and Entrepreneurship for Undergraduates(No.201610491122)
文摘Over 600 chloride-bearing deposits(chlorides) have been identified on the southern highlands of Mars. These chlorides have critical implications for hydrology and astrobiology: they are indicators of an evaporating super saturated solution, and they could have provided habitat environments for halophilic microorganisms and preserved organic matter. One of the prominent geomorphology characteristics of these chloridebearing regions is the polygonal features within them. The origin of these polygonal features is still in debate. In this study, we have surveyed 153 locations of chlorides using 441 high resolution imaging science experiment(Hi RISE) images to characterize the geomorphology of polygonal features. We identified 3 types of polygonal features of distinct geomorphologic characteristics: fractures, raised ridges, and transitional polygons between fractures and raised ridges. We evaluate previously proposed hypotheses of the formation of the polygonal features, and suggest that the 3 types of polygonal features are indicators of different stages of salt crust formation. Salt crust is usually formed through multiple groundwater activities, and it often occurs in playa environment on Earth. The unique hydrological and astrobiological implications of the chlorides with polygonal features make these deposits of high priority for future landed on and/or sample return exploration missions of Mars.
