Since time immemorial,humans have made their homes alongside waterways,and mighty rivers have been the cradles of human civilization.However,as society has evolved at an ever-accelerating pace,our relationship with th...Since time immemorial,humans have made their homes alongside waterways,and mighty rivers have been the cradles of human civilization.However,as society has evolved at an ever-accelerating pace,our relationship with these life-giving streams has shifted dramatically,from one of reverence to exploitation.Now,the profound water crisis has compelled humanity to reexamine its connection with rivers.展开更多
This study investigated the distribution of microplastics and heavy metals,along with the interaction between the two in the sediments of urban rivers in China.Results showed that the abundance of microplastics ranged...This study investigated the distribution of microplastics and heavy metals,along with the interaction between the two in the sediments of urban rivers in China.Results showed that the abundance of microplastics ranged from 2412±187.5 to 7638±1312items kg^(-1)dry sediment across different survey stations,with an average abundance at(4388±713)items kg^(-1)dry sediment.Upon further categorization,it was found that transparent fragments were the primary color and type of microplastics present.The potential ecological risk index(RI)of heavy metals in sediments suggested a low level of ecological risk within a majority of the urban rivers studied.Cd was identified as the main potential ecological risk factor in the sediments of the studied areas.There was a relatively good significant linear relationship between the RI of heavy metals and the abundance of microplastics,bolstering the linkage between these two environmental pollutants.However,the concentrations of heavy metals in microplastics were not dependent on their corresponding contents in sediments.In fact,the concentration of Cu,Cd,and As in microplastics were higher than those in the sediments.This finding confirmed that microplastics could serve as carriers of heavy metals and introduce potential risks to aquatic wildlife and human through the food chain.展开更多
The Arun and Tista Rivers,which flow across the Himalayas,are commonly known as antecedent valleys that overcame the rapid uplift of the Higher Himalayan ranges.To clarify whether the idea of antecedent rivers is acce...The Arun and Tista Rivers,which flow across the Himalayas,are commonly known as antecedent valleys that overcame the rapid uplift of the Higher Himalayan ranges.To clarify whether the idea of antecedent rivers is acceptable,we investigated the geomorphology of the Himalayas between eastern Nepal and Bhutan Himalayas.The southern part of Tibetan Plateau,extending across the Himalayas as tectonically un-deformed glaciated terrain named as'Tibetan Corridor,'does not suggest the regional uplift of the Higher Himalayas.The 8,000-m class mountains of Everest,Makalu,and Kanchenjunga are isolated residual peaks on the glaciated terrain composed of mountain peaks of 4,000–6,000 m high.The Tibetan glaciers commonly beheaded by Himalayan glaciers along the great watershed of the Himalayas suggest the expansion of Himalayan river drainage by glaciation.For the narrow upstream regions of the Arun and Tista Rivers with less precipitation behind the range,it is hard to collect enough water for the power of down-cutting their channels against the uplifting Himalayas.The fission track ages of the Higher Himalayan Crystalline Nappe suggest that the Himalayas attained their present altitude by 11–10 Ma,and the Arun and Tista Rivers formed deep gorges across the Himalayas by headward erosion.展开更多
Small mountainous rivers are characterized by large instantaneous fluxes and susceptible to extreme weather events,which can rapidly transport materials into the sea and have a significant impact on the ecological env...Small mountainous rivers are characterized by large instantaneous fluxes and susceptible to extreme weather events,which can rapidly transport materials into the sea and have a significant impact on the ecological environment of estuaries and bays.In order to investigate the seasonal characteristics of nutrients in small mountainous rivers in the subtropical monsoon region and the output pattern to the sea during heavy precipitation,surveys on the mountainous rivers were carried out in Baixi watershed in August 2020(wet season),March 2021(dry season)and June 2021(Meiyu period).The results showed that the dissolved inorganic nitrogen(DIN)of the rivers has an average concentration of 752μg L^(−1)in the wet season and 1472μg L^(−1)in the dry season.The concentrations of dissolved inorganic phosphorus(DIP)in wet season and dry season were 63μg L^(−1)and 51μg L^(−1),respectively.Influenced by the changes of land use in sub-watersheds,DIN concentrations in the mainstream increased from 701μg L^(−1)in the upper reaches to 1284μg L^(−1)in the middle reaches.Two rainstorms during the Meiyu period in the watershed caused the pulse runoff in the river.The maximum daily runoff reached 70 times that before rains.The maximum daily fluxes of DIN and DIP were 109 and 247 times that before rains,respectively.In view that the watershed experienced several rainstorms in the wet season,the river,with pulse runoff,carries a large amount of nutrients into the sea in a short time,which will have a significant impact on the environment of Sanmen bay and its adjacent sea.展开更多
The continuous decrease of low-slope cropland resources caused by construction land crowding poses huge threat to regional sustainable development and food security.Slope spectrum analysis of topographic and geomorphi...The continuous decrease of low-slope cropland resources caused by construction land crowding poses huge threat to regional sustainable development and food security.Slope spectrum analysis of topographic and geomorphic features is considered as a digital terrain analysis method which reflects the macro-topographic features by using micro-topographic factors.However,pieces of studies have extended the concept of slope spectrum in the field of geoscience to construction land to explore its expansion law,while research on the slope trend of cropland from that perspective remains rare.To address the gap,in virtue of spatial analysis and geographically weighted regression(GWR)model,the cropland use change in the Yangtze River Basin(YRB)from 2000 to 2020 was analyzed and the driving factors were explored from the perspective of slope spectrum.Results showed that the slope spectrum curves of cropland area-frequency in the YRB showed a first upward then a downward trend.The change curve of the slope spectrum of cropland in each province(municipality)exhibited various distribution patterns.Quantitative analysis of morphological parameters of cropland slope spectrum revealed that the further down the YRB,the stronger the flattening characteristics,the more obvious the concentration.The province experienced the greatest downhill cropland climbing(CLC)was Shannxi,while province experienced the highest uphill CLC was Zhejiang.The most common cropland use change type in the YRB was horizontal expansion type.The factors affecting average cropland climbing index(ACCI)were quite stable in different periods,while population density(POP)changed from negative to positive during the study period.This research is of practical significance for the rational utilization of cropland at the watershed scale.展开更多
In the history, the main roles of inland rivers in Beilun Port City of Ningbo were desalination,blocking tides, shipping, and flood control. Nowadays, with the continuous spread and deepening ofurbanization, the ecolo...In the history, the main roles of inland rivers in Beilun Port City of Ningbo were desalination,blocking tides, shipping, and flood control. Nowadays, with the continuous spread and deepening ofurbanization, the ecological environment of river courses has been destroyed. In the past, remediationmeasures based on engineering and technology played a certain role, but can not “cure the root cause”. Itshould respect the historical evolution process of river courses, and highlight the ecological service functionand leisure tourism value of river courses from the coordination perspective of urban and rural ecologicalenvironment, economic industries, society and culture in the planning ideas of ecology, production, andlife integration. Four aspects of the measures are as below: protecting and repairing the ecological matrixof river courses;building green space system and maintaining flood control functions through the waternetwork;protecting cultural heritage along the rivers;developing waterfront leisure tourism scenic area.展开更多
A study of toad infestation was carried out from July to December 2022, in the vicinity of the Mfilou and Ngamboulou Rivers, with the aim of determining the prevalence rate of parasitic carriage in these toads. After ...A study of toad infestation was carried out from July to December 2022, in the vicinity of the Mfilou and Ngamboulou Rivers, with the aim of determining the prevalence rate of parasitic carriage in these toads. After collecting 289 specimens, all belonging to the Anuran order and Bufonidae family, three species were identified: Sclerophrys camerunensis (Parker, 1936), Sclerophrys regularis (Reuss, 1834) and Sclerophrys sp. The most abundant species were Sclerophrys camerunensis, followed by Sclerophrys regularis. With regard to parasitological aspects, of the 289 specimens collected, 195 were parasitized, i.e. a percentage of 67.47%. The only parasitic species identified was Ascaris sp., which is preferentially located in the intestine.展开更多
Rivers have been degraded globally due to various reasons over centuries and limiting their ecological health and value, including Ganga River in India. Riverscape approach can provide relevant information on riverine...Rivers have been degraded globally due to various reasons over centuries and limiting their ecological health and value, including Ganga River in India. Riverscape approach can provide relevant information on riverine resources needed in river restoration programmes. We propose a conceptual riverscape model to rejuvenate the holy river Ganga in India through forestry interventions after due consideration of ecological processes, mosaic of landforms, communities and environment within the large landscape of Ganga basin. The select riverscape area includes the area of 5 km and 2 km on either side of the river Ganga and important tributaries, respectively, all along the rivers in five stakeholder states of Uttarakhand, Uttar Pradesh, Bihar, Jharkhand, and West Bengal in the country. The width of the riverscape was taken from the maximum bank line in recent years on either side of river in the concerned state. However, all micro-watersheds in the hills of Uttarakhand state, being the origin place of river, have been included in riverscape area up to Haridwar. Here riverscape is a mosaic of different land uses viz., natural ecosystems, rural and agricultural ecosystems and built-up urban environment including flood plain and is an ecologically sustained system developed during the last 30 years due to river meandering all along the river. Geospatial modelling and GIS data on land use pattern, soil erosion rates, slope of the topography, etc. were used to classify riverscape area into high, medium and low priority areas to implement forestry interventions in delineated riverscape. Thereafter, forestry interventions were planned and carried out in three identified landscapes viz., Natural (forests), Agriculture (agroforestry), and Urban along with conservation activities. Forestry interventions in delineated riverscape are expected to increase water recharge<sup> </sup>and decrease the sedimentation load in the Ganga River and its tributaries.展开更多
Background: Glaucoma is the leading cause of irreversible blindness incapacitating over 80 million people worldwide. Several pathogenetic mechanisms have been postulated to explain the optic nerve damage that occur in...Background: Glaucoma is the leading cause of irreversible blindness incapacitating over 80 million people worldwide. Several pathogenetic mechanisms have been postulated to explain the optic nerve damage that occur in POAG among which genetic predisposition is prominent. Gene-Linkage-based studies have identified genes associated with POAG: Myocilin, Optineurin, WDR36, Tank-Binding Kinase (TBK1) and APbb-2. Objective: To investigate the prevalence of myocilin gene mutation in adult-onset POAG patients and non-glaucoma subjects who are indigenes of Rivers State. Methodology: In this comparative cross-sectional study, 393 POAG patients attending the Glaucoma Clinic of UPTH were compared with 393 age and sex-matched phenotypically normal participants. Clinical assessment combined with findings from clinical records was used. Venous blood was obtained for genomic analyses. Extracted DNA was sequenced with specific primers for myocilin and polymerase chain reaction. Zymo-Bead Genomic DNA kit protocol was used to detect allelic differences. Results: Total of 786 participants participated in the study. The mean age was 59.8 ± 11.8 years. The prevalence of myocilin gene mutation (MYOC) in the study population was 5.3%, in the POAG group was 8.4%, and 2.3% in the non-glaucoma group. This observed difference was statistically significant (p = 0.001). Location of the mutant myocilin gene was in GLC1A 171638779, 171638703, 171638610 and 171638608. Conclusion: Mutations in myocilin gene are associated with adult-onset POAG in Rivers State. Its relevance as a biomarker for diagnosis of adult-onset POAG needs further investigations.展开更多
The study evaluated the environmental effects of an oil spill in Joinkrama 4 and Akimima Ahoada West LGA,Rivers State,Nigeria,using various vegetation indices.Location data for the spill were obtained from the Nigeria...The study evaluated the environmental effects of an oil spill in Joinkrama 4 and Akimima Ahoada West LGA,Rivers State,Nigeria,using various vegetation indices.Location data for the spill were obtained from the Nigeria Oil Spill Detection and Response Agency,and Landsat imagery was acquired from the United States Geological Survey.Three soil samples were collected from the affected area,and their analysis included measuring total petroleum hydrocarbons(TPH),total hydrocarbons(THC),and polycyclic aromatic hydrocarbons(PAH).The obtained data were processed with ArcGIS software,utilizing different vegetation indices such as the Normalized Difference Vegetation Index(NDVI),Atmospheric Resistant Vegetation Index(ARVI),Soil Adjusted Vegetation Index(SAVI),Green Short Wave Infrared(GSWIR),and Green Near Infrared(GNIR).Statistical analysis was performed using SPSS and Microsoft Excel.The results consistently indicated a negative impact on the environment resulting from the oil spill.A comparison of spectral reflectance values between the oil spill site and the non-oil spill site showed lower values at the oil spill site across all vegetation indices(NDVI 0.0665-0.2622,ARVI-0.0495-0.1268,SAVI 0.0333-0.1311,GSWIR-0.183-0.0517,GNIR-0.0104--0.1980),indicating damage to vegetation.Additionally,the study examined the correlation between vegetation indices and environmental parameters associated with the oil spill,revealing significant relationships with TPH,THC,and PAH.A t-test with a significance level of p<0.05 indicated significantly higher vegetation index values at the non-oil spill site compared to the oil spill site,suggesting a potential disparity in vegetation health between the two areas.Hence,this study emphasizes the harmful effect of oil spills on vegetation and highlights the importance of utilizing vegetation indices and spectral reflectance analysis to detect and monitor the impact of oil spills on vegetation.展开更多
The pollution of sediments by inorganic pollutants requires particularly important attention because of their toxicity, their persistence in the environment and their bioaccumulation by animal and plant life. The poll...The pollution of sediments by inorganic pollutants requires particularly important attention because of their toxicity, their persistence in the environment and their bioaccumulation by animal and plant life. The pollution of sediments by inorganic pollutants requires particularly important attention because of their toxicity, their persistence in the environment and their bioaccumulation by animal and plant living beings. This study focuses on the pollution of sediments of the Chari and Logon rivers in the city of N’Djamena by heavy metals. The objective of this study is to evaluate the degree of contamination, the geo-accumulation index and the degree of the Pollutant Loading Index of some heavy metals (Pb, Cr, Cu, Mn and Cd) and iron in the sediments of the sampled sites. The average concentrations of heavy metals and iron in the sediments are: Pb (10.00 ± 00 μg/Kg to 126 ± 16.52 μg/Kg);Cr VI (0.13 ± 00 mg/Kg to 0.21 ± 00 mg/Kg);Cd (trace);Cu (0.08 ± 0.02 mg/kg to 3.23 ± 0.64 mg/kg);Fe (0.25 ± 0.00 mg/kg to 5.79 ± 0.00 mg/kg);and Mn (0.2 ± 0.00 mg/Kg to 1.1 ± 0.00 mg/Kg);in order of highest to lowest abundance: Fe > Mn > Cd > Cu > Cr VI > Pb for the Logon;Fe > Cu > Mn > Cd > Cr VI > Pb for the Chari and Fe > Mn > Cu > Cd > Cr VI > Pb for the Confluent. The contamination factors for all heavy metals range from no contamination to low contamination for the sediments analyzed. The geo-accumulation indices indicate that the sampled sites are not polluted. The same is true for Er and RI which confirm an absence of ecological risks in the analyzed sediments.展开更多
Flooding of small and medium rivers is caused by environmental factors like rainfall and soil loosening.With the development and application of technologies such as the Internet of Things and big data,the disaster sup...Flooding of small and medium rivers is caused by environmental factors like rainfall and soil loosening.With the development and application of technologies such as the Internet of Things and big data,the disaster supervision and management of large river basins in China has improved over the years.However,due to the frequent floods in small and medium-sized rivers in our country,the current prediction and early warning of small and medium-sized rivers is not accurate enough;it is difficult to realize real-time monitoring of small and medium-sized rivers,and it is also impossible to obtain corresponding data and information in time.Therefore,the construction and application of small and medium-sized river prediction and early warning systems should be further improved.This paper presents an analysis and discussion on flood forecasting and early warning systems for small and medium-sized rivers in detail,and corresponding strategies to improve the effect of forecasting and early warning systems are proposed.展开更多
Dissolved organic matter (DOM) is closely linked to human activities in drainage basins and plays a crucial role in maintaining ecosystem functioning and reflecting environmental quality. However, the impacts of clima...Dissolved organic matter (DOM) is closely linked to human activities in drainage basins and plays a crucial role in maintaining ecosystem functioning and reflecting environmental quality. However, the impacts of climate and anthropogenic-induced changes on DOM in riverine systems under increasingly warming conditions still need to be better understood, particularly at large regional scales. To address this knowledge gap, we analyzed a dataset containing 386 published measurements for nine major Chinese river systems, examining dissolved organic carbon (DOC) concentrations and optical properties of chromophoric DOM (CDOM) under diverse envi- ronmental conditions, including mean air temperature, precipitation, surface solar radiation, population density, and land use. Our findings indicate that riverine DOC concentrations are significantly higher in northern China (at ∼46.8%) than in the south. This disparity is primarily due to the high input of soil erosion-induced DOM from drying-affected lands (57.0%), farmland (49.1%), and forests in the north. The high temperate and strong hydrological conditions would lead to DOM degradation easily in the riverine system in the south of China. Our study highlights that various climatic and anthropogenic factors, such as agriculture, vegetation coverage, soil erosion, surface solar radiation, and precipitation, individually or in combination, can affect DOM dynamics in river systems. Therefore, considering alterations in DOM dynamics resulting from climate and environmental changes is crucial for carbon-neutral policies and sustainable river ecosystem assessments.展开更多
Water conservation initiatives satisfy the demand for water supply,electricity generation,irrigation,and flood control.While helping humanity,they have also altered the ecosystem of natural rivers,impacted river ecolo...Water conservation initiatives satisfy the demand for water supply,electricity generation,irrigation,and flood control.While helping humanity,they have also altered the ecosystem of natural rivers,impacted river ecology,disrupted river continuity,and jeopardized the existence of aquatic creatures in rivers.Studying the impacts of dam construction on rivers can enhance our knowledge of river ecological and environmental concerns and help sustain the health of river ecosystems,thereby realizing the harmony between humans and water in both theoretical and practical aspects.This study used bibliometrics and constructed an author-keyword 2-mode matrix network using Co-Occurrence software to identify the hotspots and research trend in eco-hydrology of dammed rivers.We identified‘FLOW’‘SEDIMENT’‘QUALITY’and‘MODEL’as the research hotspots in the ecological impact of dammed rivers,and combined the related literatures,we highlight the research progress in the four directions.Then the research shortcomings and prospect were discussed,including strengthening the monitoring and analysis of critical ecological variables,enhancing the hydrological monitoring density for small rivers,strengthening the research of relationship between eutrophication and zooplankton,establishing multiscale approaches,and combining multi-sources information technologies to improve parameter accuracy in the model research.展开更多
Urban water system has a certain orientation for the formation and morphological evolution and development of urban space,and old residential areas are often built along the vein of the water system,which is one of th...Urban water system has a certain orientation for the formation and morphological evolution and development of urban space,and old residential areas are often built along the vein of the water system,which is one of the main media to continue the historical context of the city and create the urban regional landscape in the context of urban renewal.The old residential area of the Tiaodeng River basin in the old city of Yongchuan is taken as the research object.Under the background of urban double cultivation,community transformation is combined with urban waterfront space transformation.Around the influencing factors such as water pollution,monotonous function,and lack of style,the existing problems of the site are analyzed and summarized.Additionally,six major strategies are put forward to achieve the quality and function improvement of the old residential area in the Tiaodeng River basin:creating a water town type of landscape style,river course governance,traffic optimization,shaping cultural interface,updating business formats,and improving supporting facilities.展开更多
The study was conducted to illustrate the physical profile of the three major rivers of Eastern Samar inside the SINP to serve as a reference for the river landscape. Highlights of the profile are river width, depth, ...The study was conducted to illustrate the physical profile of the three major rivers of Eastern Samar inside the SINP to serve as a reference for the river landscape. Highlights of the profile are river width, depth, water velocity and water flow rate, potential source, river stretch, flood height and flood plain as inputs to development and disaster planning. Data presented here were based on field surveys supported and guided by reference maps. Based on the survey, a potential source of Oras and Ulot-Can-avid Rivers is San Jose de Buan, Samar while Suribao River flows from the closed-canopy forest from Borongan-Maydolong-Llorente (Eastern Samar). Flooding and erosion were observed in the three rivers, but the highest silt deposits and the widest flood plain were in Oras River, with the highest water flow rate in the upstream. Erosion and quarrying were observed in all rivers. Bamboo reforestation is conducted in Suribao River as river bank erosion control measures. Results of the survey revealed the high risk to our rivers and river villagers due to flooding and erosion, in addition to the loss of properties and livelihood, and the ecological conservation of the landscape. Collective rehabilitation measures should be crafted for a unified action to address environmental issues parallel to development plans to promote but sustainably manage our resources and protect our villagers.展开更多
The vertical profile distribution characteristics of nitrogen in core sediments of Three Rivers Estuary in Poyang Lake were studied.The results showed that TN content in core sediments ranged from 480.0 to 1 900.0 μg...The vertical profile distribution characteristics of nitrogen in core sediments of Three Rivers Estuary in Poyang Lake were studied.The results showed that TN content in core sediments ranged from 480.0 to 1 900.0 μg/g with the change of depth,which was divided into three distribution types as follows:TN content decreases gradually with the increase of depth,TN content increases gradually with the increase of depth or higher content in the middle but lower content in two ends.NH4+-N content ranged from 8.7 ...展开更多
[Objective] This study was conducted to find a restoration method suitable for urban polluted rivers. [Method] A segment of a representative river in the old part of a certain city in south Jiangsu was selected as a r...[Objective] This study was conducted to find a restoration method suitable for urban polluted rivers. [Method] A segment of a representative river in the old part of a certain city in south Jiangsu was selected as a research area through previous investigation, and the polluted river was cleaned and restored by 3 methods, i.e. artificial wetland, floating island type wetland and purification floating island. [Resuit] Floating plants (Hydrocotyle verticillata and Myriophyllum spicatum) showed better restoration effects than emergent aquatic plants (Iris wilsonii, Arundo donax, reed, water-cultured Ilex chinensis and Lythrum salicaria). The two types of plants showed the removal rates of total nitrogen of 37.9% and 34.1%, respectively, the removal rates of total phosphorous of 80.1% and 73.5%, respectively, the removal rates of COD of 81.1% and 74.8%, respectively, the removal rates of ammonia nitrogen of 80.6% and 85.9%, respectively, and the removal rates of SS of 59.1% and 77.3%, respectively. Among the purification floating island, the artificial wetland and the floating island type wetland, the purification floating land restoration technique exhibited the best removal effect, with the removal rates of 87.6%, 71.3%, 87.6%, 97.5% and 81.8% for total nitrogen, total phosphorous, ammonia nitrogen COD and SS, respectively. The nitrification and denitdfication rates of bottom mud and water samples in the engineering segment were remarkably higher than those in the reference segment, by 15.4% and 21.1%, respectively. The nitrification and denitrification rates of bottom mud in the engineering segment and the non-engineering segment were higher than those of water samples by 26.9% and 31.8%, respectively. Restoration plants showed better removal effects of total phosphorous, total nitrogen, COD and SS under aeration condition than noeration condition. [Conclusion] The purification floating island has a significant restoration effect on urban polluted river.展开更多
Water pollution is one of the current global problems.So many countries are suffering from this problem specifically most South Asian and Southeast Asian countries,and Bangladesh is one of those countries that are suf...Water pollution is one of the current global problems.So many countries are suffering from this problem specifically most South Asian and Southeast Asian countries,and Bangladesh is one of those countries that are suffering from water pollution.Furthermore,the city of Bangladesh,Dhaka is one of the most densely populated cities in the world and overpopulation is showing a negative impact on the water quality now.Most of the rivers are very polluted around Dhaka city because of anthropogenic causes.This study focused on Buriganga river pollution and its impact on public health.This study intended to find out the major cause of Buriganga river pollution and the health status of the community living beside the Buriganga river.Also the study identified all the common diseases which people are suffering from around the Buriganga river area.Then the study compared the results with other southeast Asian countries so that it can make the relationship and can make it easier to understand the current situation of water pollution on public health in East Asia and Southeast Asia regions.During the research work,it was noticed that the Buriganga river is very polluted due to human activities.The transportation system,fishing,and waste canals from industries become the primary reasons behind Buriganga’s current condition.Also irresponsibility of both the environmental department and civil society is the major factor in Buriganga river pollution.The hygienic level was also not in a good condition because so many wastes like plastic materials and other daily use materials were thrown out into the river.That’s why public health conditions around the Buriganga river become vulnerable nowadays.So policies have to be implemented from the right perspective and the institutions have to be strong enough to handle all the issues regarding the Buriganga River.展开更多
This study explores the key role of rivers in the westward expansion of the United States during the 19th century. In the early 1800s, President Jefferson envisioned a United States that extended from the Atlantic to ...This study explores the key role of rivers in the westward expansion of the United States during the 19th century. In the early 1800s, President Jefferson envisioned a United States that extended from the Atlantic to the Pacific Ocean. At the time, the entire United States territory was located between the Atlantic Ocean and the Mississippi River. Much of the land west of the Mississippi River was claimed by Spain, France, or Canada. In 1803, President Jefferson was able to purchase the Missouri River watershed from France via the Louisiana Purchase. This allowed the United States to extend its land claim west from the confluence of the Missouri and Mississippi Rivers to the head waters of the Missouri River at the continental divide in the Rocky Mountains. President Jefferson commissioned William Clark and Meriwether Lewis, in 1803, to explore, discover and describe the Missouri River watershed and find a water route to the Pacific Ocean. The Lewis and Clark Corps of Discovery trip found no such waterway link but did continue to explore the Pacific Northwest lands north and west of the continental divide. The only way that the Pacific Northwest could be claimed as part of the United States was for Americans to settle there before the Canadians did. Starting in the 1820s, many Americans traveled via the Oregon Trail to the Willamette Valley (Land of Flowing Milk and Honey) in Oregon. The primary objectives of this study are to document how the United States: 1) extended its land claims west from the Mississippi River to the North American continental drainage divide;2) established an American claim to the Pacific North West territory;and 3) fulfilled President Jefferson’s vision of a United States extending from the Atlantic to the Pacific Ocean.展开更多
文摘Since time immemorial,humans have made their homes alongside waterways,and mighty rivers have been the cradles of human civilization.However,as society has evolved at an ever-accelerating pace,our relationship with these life-giving streams has shifted dramatically,from one of reverence to exploitation.Now,the profound water crisis has compelled humanity to reexamine its connection with rivers.
基金supported by the Key Research and Development Program (Scientific and Technological Project)of Henan Province (Nos.212102310080,222102320294,and 232102231062)the Fundamental Research Funds for the Central Universities (No.220602024)the Major Focus Project of Henan Academy of Sciences (No.220102002)。
文摘This study investigated the distribution of microplastics and heavy metals,along with the interaction between the two in the sediments of urban rivers in China.Results showed that the abundance of microplastics ranged from 2412±187.5 to 7638±1312items kg^(-1)dry sediment across different survey stations,with an average abundance at(4388±713)items kg^(-1)dry sediment.Upon further categorization,it was found that transparent fragments were the primary color and type of microplastics present.The potential ecological risk index(RI)of heavy metals in sediments suggested a low level of ecological risk within a majority of the urban rivers studied.Cd was identified as the main potential ecological risk factor in the sediments of the studied areas.There was a relatively good significant linear relationship between the RI of heavy metals and the abundance of microplastics,bolstering the linkage between these two environmental pollutants.However,the concentrations of heavy metals in microplastics were not dependent on their corresponding contents in sediments.In fact,the concentration of Cu,Cd,and As in microplastics were higher than those in the sediments.This finding confirmed that microplastics could serve as carriers of heavy metals and introduce potential risks to aquatic wildlife and human through the food chain.
基金This work was supported by Grants-in-Aid for Scientific Research of the Japanese Society for the Promotion of Science(JSPS KAKENHI)Grant Number 18H00766(principal investigator:Takashi Nakata)Grant Number 18KK0027(principal investigator:Yasuhiro Kumahara).
文摘The Arun and Tista Rivers,which flow across the Himalayas,are commonly known as antecedent valleys that overcame the rapid uplift of the Higher Himalayan ranges.To clarify whether the idea of antecedent rivers is acceptable,we investigated the geomorphology of the Himalayas between eastern Nepal and Bhutan Himalayas.The southern part of Tibetan Plateau,extending across the Himalayas as tectonically un-deformed glaciated terrain named as'Tibetan Corridor,'does not suggest the regional uplift of the Higher Himalayas.The 8,000-m class mountains of Everest,Makalu,and Kanchenjunga are isolated residual peaks on the glaciated terrain composed of mountain peaks of 4,000–6,000 m high.The Tibetan glaciers commonly beheaded by Himalayan glaciers along the great watershed of the Himalayas suggest the expansion of Himalayan river drainage by glaciation.For the narrow upstream regions of the Arun and Tista Rivers with less precipitation behind the range,it is hard to collect enough water for the power of down-cutting their channels against the uplifting Himalayas.The fission track ages of the Higher Himalayan Crystalline Nappe suggest that the Himalayas attained their present altitude by 11–10 Ma,and the Arun and Tista Rivers formed deep gorges across the Himalayas by headward erosion.
基金financially supported by the Postdoctoral Foundation of Qingdao(Pb Isotopes of Oujiang River to Quantitatively Identify Sediment Provenance in Oujiang Estuary and Adjacent Area)the China Geological Survey Project(No.DD20190276)the Fund of Ministry of Science and Technology(Nos.2013FY112200 and 2019YFE0127200).
文摘Small mountainous rivers are characterized by large instantaneous fluxes and susceptible to extreme weather events,which can rapidly transport materials into the sea and have a significant impact on the ecological environment of estuaries and bays.In order to investigate the seasonal characteristics of nutrients in small mountainous rivers in the subtropical monsoon region and the output pattern to the sea during heavy precipitation,surveys on the mountainous rivers were carried out in Baixi watershed in August 2020(wet season),March 2021(dry season)and June 2021(Meiyu period).The results showed that the dissolved inorganic nitrogen(DIN)of the rivers has an average concentration of 752μg L^(−1)in the wet season and 1472μg L^(−1)in the dry season.The concentrations of dissolved inorganic phosphorus(DIP)in wet season and dry season were 63μg L^(−1)and 51μg L^(−1),respectively.Influenced by the changes of land use in sub-watersheds,DIN concentrations in the mainstream increased from 701μg L^(−1)in the upper reaches to 1284μg L^(−1)in the middle reaches.Two rainstorms during the Meiyu period in the watershed caused the pulse runoff in the river.The maximum daily runoff reached 70 times that before rains.The maximum daily fluxes of DIN and DIP were 109 and 247 times that before rains,respectively.In view that the watershed experienced several rainstorms in the wet season,the river,with pulse runoff,carries a large amount of nutrients into the sea in a short time,which will have a significant impact on the environment of Sanmen bay and its adjacent sea.
基金supported in part by the Key Laboratory of Natural Resources Monitoring and Supervision in Southern Hilly Region,Ministry of Natural Resources(NRMSSHR2023Y02)Yunnan Key Laboratory of Plateau Geographic Processes and Environmental Changes(PGPEC2304)+1 种基金Yunnan Normal University,China.This study was also sponsored by the Scientific Research Project of Education Department of Hubei Province(Grant No.B2022262)the Philosophy and Social Sciences Research Project of Education Department of Hubei Province(Grant No.22G024).
文摘The continuous decrease of low-slope cropland resources caused by construction land crowding poses huge threat to regional sustainable development and food security.Slope spectrum analysis of topographic and geomorphic features is considered as a digital terrain analysis method which reflects the macro-topographic features by using micro-topographic factors.However,pieces of studies have extended the concept of slope spectrum in the field of geoscience to construction land to explore its expansion law,while research on the slope trend of cropland from that perspective remains rare.To address the gap,in virtue of spatial analysis and geographically weighted regression(GWR)model,the cropland use change in the Yangtze River Basin(YRB)from 2000 to 2020 was analyzed and the driving factors were explored from the perspective of slope spectrum.Results showed that the slope spectrum curves of cropland area-frequency in the YRB showed a first upward then a downward trend.The change curve of the slope spectrum of cropland in each province(municipality)exhibited various distribution patterns.Quantitative analysis of morphological parameters of cropland slope spectrum revealed that the further down the YRB,the stronger the flattening characteristics,the more obvious the concentration.The province experienced the greatest downhill cropland climbing(CLC)was Shannxi,while province experienced the highest uphill CLC was Zhejiang.The most common cropland use change type in the YRB was horizontal expansion type.The factors affecting average cropland climbing index(ACCI)were quite stable in different periods,while population density(POP)changed from negative to positive during the study period.This research is of practical significance for the rational utilization of cropland at the watershed scale.
文摘In the history, the main roles of inland rivers in Beilun Port City of Ningbo were desalination,blocking tides, shipping, and flood control. Nowadays, with the continuous spread and deepening ofurbanization, the ecological environment of river courses has been destroyed. In the past, remediationmeasures based on engineering and technology played a certain role, but can not “cure the root cause”. Itshould respect the historical evolution process of river courses, and highlight the ecological service functionand leisure tourism value of river courses from the coordination perspective of urban and rural ecologicalenvironment, economic industries, society and culture in the planning ideas of ecology, production, andlife integration. Four aspects of the measures are as below: protecting and repairing the ecological matrixof river courses;building green space system and maintaining flood control functions through the waternetwork;protecting cultural heritage along the rivers;developing waterfront leisure tourism scenic area.
文摘A study of toad infestation was carried out from July to December 2022, in the vicinity of the Mfilou and Ngamboulou Rivers, with the aim of determining the prevalence rate of parasitic carriage in these toads. After collecting 289 specimens, all belonging to the Anuran order and Bufonidae family, three species were identified: Sclerophrys camerunensis (Parker, 1936), Sclerophrys regularis (Reuss, 1834) and Sclerophrys sp. The most abundant species were Sclerophrys camerunensis, followed by Sclerophrys regularis. With regard to parasitological aspects, of the 289 specimens collected, 195 were parasitized, i.e. a percentage of 67.47%. The only parasitic species identified was Ascaris sp., which is preferentially located in the intestine.
文摘Rivers have been degraded globally due to various reasons over centuries and limiting their ecological health and value, including Ganga River in India. Riverscape approach can provide relevant information on riverine resources needed in river restoration programmes. We propose a conceptual riverscape model to rejuvenate the holy river Ganga in India through forestry interventions after due consideration of ecological processes, mosaic of landforms, communities and environment within the large landscape of Ganga basin. The select riverscape area includes the area of 5 km and 2 km on either side of the river Ganga and important tributaries, respectively, all along the rivers in five stakeholder states of Uttarakhand, Uttar Pradesh, Bihar, Jharkhand, and West Bengal in the country. The width of the riverscape was taken from the maximum bank line in recent years on either side of river in the concerned state. However, all micro-watersheds in the hills of Uttarakhand state, being the origin place of river, have been included in riverscape area up to Haridwar. Here riverscape is a mosaic of different land uses viz., natural ecosystems, rural and agricultural ecosystems and built-up urban environment including flood plain and is an ecologically sustained system developed during the last 30 years due to river meandering all along the river. Geospatial modelling and GIS data on land use pattern, soil erosion rates, slope of the topography, etc. were used to classify riverscape area into high, medium and low priority areas to implement forestry interventions in delineated riverscape. Thereafter, forestry interventions were planned and carried out in three identified landscapes viz., Natural (forests), Agriculture (agroforestry), and Urban along with conservation activities. Forestry interventions in delineated riverscape are expected to increase water recharge<sup> </sup>and decrease the sedimentation load in the Ganga River and its tributaries.
文摘Background: Glaucoma is the leading cause of irreversible blindness incapacitating over 80 million people worldwide. Several pathogenetic mechanisms have been postulated to explain the optic nerve damage that occur in POAG among which genetic predisposition is prominent. Gene-Linkage-based studies have identified genes associated with POAG: Myocilin, Optineurin, WDR36, Tank-Binding Kinase (TBK1) and APbb-2. Objective: To investigate the prevalence of myocilin gene mutation in adult-onset POAG patients and non-glaucoma subjects who are indigenes of Rivers State. Methodology: In this comparative cross-sectional study, 393 POAG patients attending the Glaucoma Clinic of UPTH were compared with 393 age and sex-matched phenotypically normal participants. Clinical assessment combined with findings from clinical records was used. Venous blood was obtained for genomic analyses. Extracted DNA was sequenced with specific primers for myocilin and polymerase chain reaction. Zymo-Bead Genomic DNA kit protocol was used to detect allelic differences. Results: Total of 786 participants participated in the study. The mean age was 59.8 ± 11.8 years. The prevalence of myocilin gene mutation (MYOC) in the study population was 5.3%, in the POAG group was 8.4%, and 2.3% in the non-glaucoma group. This observed difference was statistically significant (p = 0.001). Location of the mutant myocilin gene was in GLC1A 171638779, 171638703, 171638610 and 171638608. Conclusion: Mutations in myocilin gene are associated with adult-onset POAG in Rivers State. Its relevance as a biomarker for diagnosis of adult-onset POAG needs further investigations.
文摘The study evaluated the environmental effects of an oil spill in Joinkrama 4 and Akimima Ahoada West LGA,Rivers State,Nigeria,using various vegetation indices.Location data for the spill were obtained from the Nigeria Oil Spill Detection and Response Agency,and Landsat imagery was acquired from the United States Geological Survey.Three soil samples were collected from the affected area,and their analysis included measuring total petroleum hydrocarbons(TPH),total hydrocarbons(THC),and polycyclic aromatic hydrocarbons(PAH).The obtained data were processed with ArcGIS software,utilizing different vegetation indices such as the Normalized Difference Vegetation Index(NDVI),Atmospheric Resistant Vegetation Index(ARVI),Soil Adjusted Vegetation Index(SAVI),Green Short Wave Infrared(GSWIR),and Green Near Infrared(GNIR).Statistical analysis was performed using SPSS and Microsoft Excel.The results consistently indicated a negative impact on the environment resulting from the oil spill.A comparison of spectral reflectance values between the oil spill site and the non-oil spill site showed lower values at the oil spill site across all vegetation indices(NDVI 0.0665-0.2622,ARVI-0.0495-0.1268,SAVI 0.0333-0.1311,GSWIR-0.183-0.0517,GNIR-0.0104--0.1980),indicating damage to vegetation.Additionally,the study examined the correlation between vegetation indices and environmental parameters associated with the oil spill,revealing significant relationships with TPH,THC,and PAH.A t-test with a significance level of p<0.05 indicated significantly higher vegetation index values at the non-oil spill site compared to the oil spill site,suggesting a potential disparity in vegetation health between the two areas.Hence,this study emphasizes the harmful effect of oil spills on vegetation and highlights the importance of utilizing vegetation indices and spectral reflectance analysis to detect and monitor the impact of oil spills on vegetation.
文摘The pollution of sediments by inorganic pollutants requires particularly important attention because of their toxicity, their persistence in the environment and their bioaccumulation by animal and plant life. The pollution of sediments by inorganic pollutants requires particularly important attention because of their toxicity, their persistence in the environment and their bioaccumulation by animal and plant living beings. This study focuses on the pollution of sediments of the Chari and Logon rivers in the city of N’Djamena by heavy metals. The objective of this study is to evaluate the degree of contamination, the geo-accumulation index and the degree of the Pollutant Loading Index of some heavy metals (Pb, Cr, Cu, Mn and Cd) and iron in the sediments of the sampled sites. The average concentrations of heavy metals and iron in the sediments are: Pb (10.00 ± 00 μg/Kg to 126 ± 16.52 μg/Kg);Cr VI (0.13 ± 00 mg/Kg to 0.21 ± 00 mg/Kg);Cd (trace);Cu (0.08 ± 0.02 mg/kg to 3.23 ± 0.64 mg/kg);Fe (0.25 ± 0.00 mg/kg to 5.79 ± 0.00 mg/kg);and Mn (0.2 ± 0.00 mg/Kg to 1.1 ± 0.00 mg/Kg);in order of highest to lowest abundance: Fe > Mn > Cd > Cu > Cr VI > Pb for the Logon;Fe > Cu > Mn > Cd > Cr VI > Pb for the Chari and Fe > Mn > Cu > Cd > Cr VI > Pb for the Confluent. The contamination factors for all heavy metals range from no contamination to low contamination for the sediments analyzed. The geo-accumulation indices indicate that the sampled sites are not polluted. The same is true for Er and RI which confirm an absence of ecological risks in the analyzed sediments.
文摘Flooding of small and medium rivers is caused by environmental factors like rainfall and soil loosening.With the development and application of technologies such as the Internet of Things and big data,the disaster supervision and management of large river basins in China has improved over the years.However,due to the frequent floods in small and medium-sized rivers in our country,the current prediction and early warning of small and medium-sized rivers is not accurate enough;it is difficult to realize real-time monitoring of small and medium-sized rivers,and it is also impossible to obtain corresponding data and information in time.Therefore,the construction and application of small and medium-sized river prediction and early warning systems should be further improved.This paper presents an analysis and discussion on flood forecasting and early warning systems for small and medium-sized rivers in detail,and corresponding strategies to improve the effect of forecasting and early warning systems are proposed.
基金the National Natural Science Foun-dation of China(Grants No.41925002,42221001,42230509)received financial support from the Haihe Laboratory of Sustainable Chemical Transformations.
文摘Dissolved organic matter (DOM) is closely linked to human activities in drainage basins and plays a crucial role in maintaining ecosystem functioning and reflecting environmental quality. However, the impacts of climate and anthropogenic-induced changes on DOM in riverine systems under increasingly warming conditions still need to be better understood, particularly at large regional scales. To address this knowledge gap, we analyzed a dataset containing 386 published measurements for nine major Chinese river systems, examining dissolved organic carbon (DOC) concentrations and optical properties of chromophoric DOM (CDOM) under diverse envi- ronmental conditions, including mean air temperature, precipitation, surface solar radiation, population density, and land use. Our findings indicate that riverine DOC concentrations are significantly higher in northern China (at ∼46.8%) than in the south. This disparity is primarily due to the high input of soil erosion-induced DOM from drying-affected lands (57.0%), farmland (49.1%), and forests in the north. The high temperate and strong hydrological conditions would lead to DOM degradation easily in the riverine system in the south of China. Our study highlights that various climatic and anthropogenic factors, such as agriculture, vegetation coverage, soil erosion, surface solar radiation, and precipitation, individually or in combination, can affect DOM dynamics in river systems. Therefore, considering alterations in DOM dynamics resulting from climate and environmental changes is crucial for carbon-neutral policies and sustainable river ecosystem assessments.
基金Under the auspices of National Key R&D Program of China(No.2019YFC0409104)。
文摘Water conservation initiatives satisfy the demand for water supply,electricity generation,irrigation,and flood control.While helping humanity,they have also altered the ecosystem of natural rivers,impacted river ecology,disrupted river continuity,and jeopardized the existence of aquatic creatures in rivers.Studying the impacts of dam construction on rivers can enhance our knowledge of river ecological and environmental concerns and help sustain the health of river ecosystems,thereby realizing the harmony between humans and water in both theoretical and practical aspects.This study used bibliometrics and constructed an author-keyword 2-mode matrix network using Co-Occurrence software to identify the hotspots and research trend in eco-hydrology of dammed rivers.We identified‘FLOW’‘SEDIMENT’‘QUALITY’and‘MODEL’as the research hotspots in the ecological impact of dammed rivers,and combined the related literatures,we highlight the research progress in the four directions.Then the research shortcomings and prospect were discussed,including strengthening the monitoring and analysis of critical ecological variables,enhancing the hydrological monitoring density for small rivers,strengthening the research of relationship between eutrophication and zooplankton,establishing multiscale approaches,and combining multi-sources information technologies to improve parameter accuracy in the model research.
基金the Chongqing Social Science Planning Project(2022NDYB83)the National Natural Science Foundation of China(52008062).
文摘Urban water system has a certain orientation for the formation and morphological evolution and development of urban space,and old residential areas are often built along the vein of the water system,which is one of the main media to continue the historical context of the city and create the urban regional landscape in the context of urban renewal.The old residential area of the Tiaodeng River basin in the old city of Yongchuan is taken as the research object.Under the background of urban double cultivation,community transformation is combined with urban waterfront space transformation.Around the influencing factors such as water pollution,monotonous function,and lack of style,the existing problems of the site are analyzed and summarized.Additionally,six major strategies are put forward to achieve the quality and function improvement of the old residential area in the Tiaodeng River basin:creating a water town type of landscape style,river course governance,traffic optimization,shaping cultural interface,updating business formats,and improving supporting facilities.
文摘The study was conducted to illustrate the physical profile of the three major rivers of Eastern Samar inside the SINP to serve as a reference for the river landscape. Highlights of the profile are river width, depth, water velocity and water flow rate, potential source, river stretch, flood height and flood plain as inputs to development and disaster planning. Data presented here were based on field surveys supported and guided by reference maps. Based on the survey, a potential source of Oras and Ulot-Can-avid Rivers is San Jose de Buan, Samar while Suribao River flows from the closed-canopy forest from Borongan-Maydolong-Llorente (Eastern Samar). Flooding and erosion were observed in the three rivers, but the highest silt deposits and the widest flood plain were in Oras River, with the highest water flow rate in the upstream. Erosion and quarrying were observed in all rivers. Bamboo reforestation is conducted in Suribao River as river bank erosion control measures. Results of the survey revealed the high risk to our rivers and river villagers due to flooding and erosion, in addition to the loss of properties and livelihood, and the ecological conservation of the landscape. Collective rehabilitation measures should be crafted for a unified action to address environmental issues parallel to development plans to promote but sustainably manage our resources and protect our villagers.
基金Supported by Science and Technology Project from Jiangxi Provincial Department of Education(GJJ09430)International Scienceand Technology Cooperation Project(2006DFB91920)NationalKey Water Project(2008ZX07526-008)~~
文摘The vertical profile distribution characteristics of nitrogen in core sediments of Three Rivers Estuary in Poyang Lake were studied.The results showed that TN content in core sediments ranged from 480.0 to 1 900.0 μg/g with the change of depth,which was divided into three distribution types as follows:TN content decreases gradually with the increase of depth,TN content increases gradually with the increase of depth or higher content in the middle but lower content in two ends.NH4+-N content ranged from 8.7 ...
文摘[Objective] This study was conducted to find a restoration method suitable for urban polluted rivers. [Method] A segment of a representative river in the old part of a certain city in south Jiangsu was selected as a research area through previous investigation, and the polluted river was cleaned and restored by 3 methods, i.e. artificial wetland, floating island type wetland and purification floating island. [Resuit] Floating plants (Hydrocotyle verticillata and Myriophyllum spicatum) showed better restoration effects than emergent aquatic plants (Iris wilsonii, Arundo donax, reed, water-cultured Ilex chinensis and Lythrum salicaria). The two types of plants showed the removal rates of total nitrogen of 37.9% and 34.1%, respectively, the removal rates of total phosphorous of 80.1% and 73.5%, respectively, the removal rates of COD of 81.1% and 74.8%, respectively, the removal rates of ammonia nitrogen of 80.6% and 85.9%, respectively, and the removal rates of SS of 59.1% and 77.3%, respectively. Among the purification floating island, the artificial wetland and the floating island type wetland, the purification floating land restoration technique exhibited the best removal effect, with the removal rates of 87.6%, 71.3%, 87.6%, 97.5% and 81.8% for total nitrogen, total phosphorous, ammonia nitrogen COD and SS, respectively. The nitrification and denitdfication rates of bottom mud and water samples in the engineering segment were remarkably higher than those in the reference segment, by 15.4% and 21.1%, respectively. The nitrification and denitrification rates of bottom mud in the engineering segment and the non-engineering segment were higher than those of water samples by 26.9% and 31.8%, respectively. Restoration plants showed better removal effects of total phosphorous, total nitrogen, COD and SS under aeration condition than noeration condition. [Conclusion] The purification floating island has a significant restoration effect on urban polluted river.
文摘Water pollution is one of the current global problems.So many countries are suffering from this problem specifically most South Asian and Southeast Asian countries,and Bangladesh is one of those countries that are suffering from water pollution.Furthermore,the city of Bangladesh,Dhaka is one of the most densely populated cities in the world and overpopulation is showing a negative impact on the water quality now.Most of the rivers are very polluted around Dhaka city because of anthropogenic causes.This study focused on Buriganga river pollution and its impact on public health.This study intended to find out the major cause of Buriganga river pollution and the health status of the community living beside the Buriganga river.Also the study identified all the common diseases which people are suffering from around the Buriganga river area.Then the study compared the results with other southeast Asian countries so that it can make the relationship and can make it easier to understand the current situation of water pollution on public health in East Asia and Southeast Asia regions.During the research work,it was noticed that the Buriganga river is very polluted due to human activities.The transportation system,fishing,and waste canals from industries become the primary reasons behind Buriganga’s current condition.Also irresponsibility of both the environmental department and civil society is the major factor in Buriganga river pollution.The hygienic level was also not in a good condition because so many wastes like plastic materials and other daily use materials were thrown out into the river.That’s why public health conditions around the Buriganga river become vulnerable nowadays.So policies have to be implemented from the right perspective and the institutions have to be strong enough to handle all the issues regarding the Buriganga River.
文摘This study explores the key role of rivers in the westward expansion of the United States during the 19th century. In the early 1800s, President Jefferson envisioned a United States that extended from the Atlantic to the Pacific Ocean. At the time, the entire United States territory was located between the Atlantic Ocean and the Mississippi River. Much of the land west of the Mississippi River was claimed by Spain, France, or Canada. In 1803, President Jefferson was able to purchase the Missouri River watershed from France via the Louisiana Purchase. This allowed the United States to extend its land claim west from the confluence of the Missouri and Mississippi Rivers to the head waters of the Missouri River at the continental divide in the Rocky Mountains. President Jefferson commissioned William Clark and Meriwether Lewis, in 1803, to explore, discover and describe the Missouri River watershed and find a water route to the Pacific Ocean. The Lewis and Clark Corps of Discovery trip found no such waterway link but did continue to explore the Pacific Northwest lands north and west of the continental divide. The only way that the Pacific Northwest could be claimed as part of the United States was for Americans to settle there before the Canadians did. Starting in the 1820s, many Americans traveled via the Oregon Trail to the Willamette Valley (Land of Flowing Milk and Honey) in Oregon. The primary objectives of this study are to document how the United States: 1) extended its land claims west from the Mississippi River to the North American continental drainage divide;2) established an American claim to the Pacific North West territory;and 3) fulfilled President Jefferson’s vision of a United States extending from the Atlantic to the Pacific Ocean.