Quantitative Estimation on Contributions of Climate Changes and Human Activities to Decreasing Runoff in Weihe River Basin, China

Human activities and climate changes are deemed to be two primary driving factors influencing the changes of hydrological processes, and quantitatively separating their influences on runoff changes will be of great significance to regional water resources planning and management. In this study, the impact of climate changes and human activities was initially qualitatively distinguished through a coupled water and energy budgets analysis, and then this effect was further separated by means of a quantitative estimation based on hydrological sensitivity analysis. The results show that: 1) precipitation, wind speed, potential evapotranspiration and runoff have a significantly decreasing trend, while temperature has a remarkably increasing tendency in the Weihe River Basin, China; 2) the major driving factor on runoff decrease in the 1970 s and 1990 s in the basin is climate changes compared with that in the baseline 1960 s, while that in the 1980 s and 2000 s is human activities. Compared with the results based on Variable Infiltration Capacity(VIC) model, the contributions calculated in this study have certain reliability. The results are of great significance to local water resources planning and management.

Application of the InVEST model for assessing water yield and its response to precipitation and land use in the Weihe River Basin, China

With realizing the importance of ecosystem services to society, the efforts to evaluate the ecosystem services have increased. As the largest tributary of the Yellow River, the Weihe River has been endowed with many ecological service functions. Among which, water yield can be a measure of local availability of water and an index for evaluating the conservation function of the region. This study aimed to explore the temporal and spatial variation of water yield and its influencing factors in the Weihe River Basin(WRB), and provide basis for formulating reasonable water resources utilization schemes. Based on the InVEST(integrated valuation of ecosystem services and tradeoffs) model, this study simulated the water yield in the WRB from 1985 to 2019, and discussed the impacts of climatic factors and land use change on water yield by spatial autocorrelation analysis and scenario analysis methods. The results showed that there was a slight increasing trend in water yield in the WRB over the study period with the increasing rate of 4.84 mm/10a and an average depth of 83.14 mm. The main water-producing areas were concentrated along the mainstream of the Weihe River and in the southern basin. Changes in water yield were comprehensively affected by climate and underlying surface factors. Precipitation was the main factor affecting water yield, which was consistent with water yield in time. And there existed significant spatial agglomeration between water yield and precipitation. Land use had little impact on the amount of water yield, but had an impact on its spatial distribution. Water yield was higher in areas with wide distribution of construction land and grassland. Water yield of different land use types were different. Unused land showed the largest water yield capacity, whereas grassland and farmland contributed most to the total water yield. The increasing water yield in the basin indicates an enhanced water supply service function of the ecosystem. These results are of great significance to the water resources management of the WRB.

Origin of Mountain Passes across Continental Divide Segments Surrounding the Southwest Montana Big Hole and Beaverhead River Drainage Basins, USA

The evolution of southwest Montana’s Big Hole and Beaverhead River drainage basins is determined from topographic map evidence related to mountain passes crossing what are today high altitude drainage divides including North America’s east-west Continental Divide. Map evidence, such as orientations of valleys leading away from mountain passes (and saddles) and barbed tributaries found along the downstream drainage routes, is used to reconstruct flow directions of streams and rivers that once crossed the present-day high mountain divides. Large south-oriented anastomosing complexes of diverging and converging channels are interpreted to have eroded what are today closely spaced passes and saddles now notched into high mountain ridges. Water in those south-oriented channels is interpreted to have flowed across emerging mountains and subsiding basins. Headward erosion of deeper southeast-oriented valleys, assisted by crustal warping, concentrated south-oriented water in fewer and deeper valleys as the water flowed from southwest Montana into what are today Idaho and the Snake River drainage basin. Headward erosion of the Big Hole River valley between the emerging Anaconda and Pioneer Mountains, also assisted by crustal warping, reversed all Big Hole Basin drainage so as to create the north-, east-, and south-oriented Big Hole River drainage route. A final and even more major reversal of flow in the present-day north-oriented Montana Missouri River valley, with the assistance of additional crustal warping, next ended all remaining flow to Idaho and the Snake River drainage basin and reversed and captured all drainage in the present-day north-oriented Big Hole, Beaverhead, and Red Rock River drainage basins. The observed map evidence indicates that prior to the final flow reversal events, large volumes of south-oriented water flowed across southwest Montana’s Big Hole and Beaverhead River drainage basins.

Spatial-temporal Analysis and Prediction of Precipitation Extremes: A Case Study in the Weihe River Basin, China

Extreme precipitation events bring considerable risks to the natural ecosystem and human life.Investigating the spatial-temporal characteristics of extreme precipitation and predicting it quantitatively are critical for the flood prevention and water resources planning and management.In this study,daily precipitation data(1957–2019)were collected from 24 meteorological stations in the Weihe River Basin(WRB),Northwest China and its surrounding areas.We first analyzed the spatial-temporal change of precipitation extremes in the WRB based on space-time cube(STC),and then predicted precipitation extremes using long short-term memory(LSTM)network,auto-regressive integrated moving average(ARIMA),and hybrid ensemble empirical mode decomposition(EEMD)-LSTM-ARIMA models.The precipitation extremes increased as the spatial variation from northwest to southeast of the WRB.There were two clusters for each extreme precipitation index,which were distributed in the northwestern and southeastern or northern and southern of the WRB.The precipitation extremes in the WRB present a strong clustering pattern.Spatially,the pattern of only high-high cluster and only low-low cluster were primarily located in lower reaches and upper reaches of the WRB,respectively.Hot spots(25.00%–50.00%)were more than cold spots(4.17%–25.00%)in the WRB.Cold spots were mainly concentrated in the northwestern part,while hot spots were mostly located in the eastern and southern parts.For different extreme precipitation indices,the performances of the different models were different.The accuracy ranking was EEMD-LSTM-ARIMA>LSTM>ARIMA in predicting simple daily intensity index(SDII)and consecutive wet days(CWD),while the accuracy ranking was LSTM>EEMD-LSTM-ARIMA>ARIMA in predicting very wet days(R95 P).The hybrid EEMD-LSTM-ARIMA model proposed was generally superior to single models in the prediction of precipitation extremes.

Runoff characteristics and its sensitivity to climate factors in the Weihe River Basin from 2006 to 2018

Exploring the current runoff characteristics after the large-scale implementation of the Grain for Green(GFG)project and investigating its sensitivities to potential drivers are crucial for water resource prediction and management.Based on the measured runoff data of 62 hydrological stations in the Weihe River Basin(WRB)from 2006 to 2018,we analyzed the temporal and spatial runoff characteristics in this study.Correlation analysis was used to investigate the relationships between different runoff indicators and climate-related factors.Additionally,an improved Budyko framework was applied to assess the sensitivities of annual runoff to precipitation,potential evaporation,and other factors.The results showed that the daily runoff flow duration curves(FDCs)of all selected hydrological stations fall in three narrow ranges,with the corresponding mean annual runoff spanning approximately 1.50 orders of magnitude,indicating that the runoff of different hydrological stations in the WRB varied greatly.The trend analysis of runoff under different exceedance frequencies showed that the runoff from the south bank of the Weihe River was more affluent and stable than that from the north bank.The runoff was unevenly distributed throughout the year,mainly in the flood season,accounting for more than 50.00%of the annual runoff.However,the trend of annual runoff change was not obvious in most areas.Correlation analysis showed that rare-frequency runoff events were more susceptible to climate factors.In this study,daily runoff under 10%-20%exceeding frequencies,consecutive maximum daily runoff,and low-runoff variability rate had strong correlations with precipitation,aridity index,and average runoff depth on rainy days.In comparison,daily runoff under 50%-99%exceeding frequencies,consecutive minimum daily runoff,and high-runoff variability rate had weak correlations with all selected impact factors.The sensitivity analysis results suggested that the sensitivity of annual runoff to precipitation was always higher than that to potential evaporation.The runoff about 87.10%of the selected hydrological stations were most sensitive to precipitation changes,and 12.90%were most sensitive to other factors.The spatial pattern of the sensitivity analysis indicated that in relatively humid southern areas,runoff was more sensitive to potential evaporation and other factors,and less sensitive to precipitation.

Driving forces behind the spatiotemporal heterogeneity of land-use and land-cover change:A case study of the Weihe River Basin,China

The impact of socioeconomic development on land-use and land-cover change(LUCC)in river basins varies spatially and temporally.Exploring the spatiotemporal evolutionary trends and drivers of LUCC under regional disparities is the basis for the sustainable development and management of basins.In this study,the Weihe River Basin(WRB)in China was selected as a typical basin,and the WRB was divided into the upstream of the Weihe River Basin(UWRB),the midstream of the Weihe River Basin(MWRB),the downstream of the Weihe River Basin(DWRB),the Jinghe River Basin(JRB),and the Luohe River Basin(LRB).Based on land-use data(cultivated land,forestland,grassland,built-up land,bare land,and water body)from 1985 to 2020,we analyzed the spatiotemporal heterogeneity of LUCC in the WRB using a land-use transfer matrix and a dynamic change model.The driving forces of LUCC in the WRB in different periods were detected using the GeoDetector,and the selected influencing factors included meteorological factors(precipitation and temperature),natural factors(elevation,slope,soil,and distance to rivers),social factors(distance to national highway,distance to railway,distance to provincial highway,and distance to expressway),and human activity factors(population density and gross domestic product(GDP)).The results indicated that the types and intensities of LUCC conversions showed considerable disparities across different sub-basins,where complex conversions among cultivated land,forestland,and grassland occurred in the LRB,JRB,and UWRB,with higher dynamic change before 2000.The conversion of other land-use types to built-up land was concentrated in the UWRB,MWRB,and DWRB,with substantial increases after 2000.Additionally,the driving effects of the influencing factors on LUCC in each sub-basin also exhibited distinct diversity,with the LRB and JRB being influenced by the meteorological and social factors,and the UWRB,MWRB,and DWRB being driven by human activity factors.Moreover,the interaction of these influencing factors indicated an enhanced effect on LUCC.This study confirmed the spatiotemporal heterogeneity effects of socioeconomic status on LUCC in the WRB under regional differences,contributing to the sustainable development of the whole basin by managing sub-basins according to local conditions.

Evapotranspiration Estimation and Influence on Water Change in the Weihe River Basin,China

As the largest sub-basin of the middle reaches of the Yellow River with an obvious decreasing trend in annual runoff in recent years,the Weihe River basin is a significant region with regard to the protection and improvement of the environment in West China.Evapotranspiration(ET)is the loss of water from the Earth’s surface to the atmosphere and plays an important role in the regional water cycle,especially when considering water resource shortages.In this study,through analyzing the grid precipitation data after interpolation from 39 meteorological stations in and around the Weihe River basin from 1981 to 2011,certain periods during 1987,1993,1999,2001,2002 and 2009 with similar precipitation characteristics had been chosen for estimating the ET in the Weihe River basin.To illustrate ET’s influence on the water budget,these estimations are calculated based on an improved Penman-Monteith equation as well as remote sensing data and meteorological data.The results show that:(1)the annual ET in the Weihe River basin ranged from 350mm to 400mm in 1987,1993,1999,2001,2002 and 2009,accounting for more than 70%of the corresponding annual precipitation.There is a definite increasing trend in different decades that is primarily distributed during the summer.(2)The spatial distribution patterns of the ET in the six years mentioned area unique set,and the years are roughly identical with more than 500mm in the middle and lower reaches of the Weihe River in the southeastern region and less than 400mm in upper reaches of the Jinghe River in the northwestern area.(3)At the single-point scale,the coefficient of determination(R2)is 0.618 compared to the eddy correlation measurements in 2009 at the Changwu site,showing good agreement between the estimated ET and the observed ET.At the basin scale,the model-estimated ET is slightly lower than the actual ET with regard to the surface water budget.Additionally,the estimated ET in 2001,2002 and 2009 is close to the MODIS ET product.(4)For similar precipitation conditions,the regional amount of water shows a decreasing tendency with increasing ET,which may result from the rise in NDVI and improvements in vegetation coverage caused by human activities.This research suggests the influence of ET on water change at the basin level,which can also explain the decreasing runoff and can provide necessary information for improved water resource management.

Drought monitoring and reliability evaluation of the latest TMPA precipitation data in the Weihe River Basin, Northwest China

The high resolution satellite precipitation products bear great potential for large-scale drought monitoring, especially for those regions with sparsely or even without gauge coverage. This study focuses on utilizing the latest Version-7 TRMM Multi-satellite Precipitation Analysis （TMPA 3B42V7） data for drought condition monitoring in the Weihe River Basin （0.135×10^6 km2）. The accuracy of the monthly TMPA 3B42V7 satellite precipitation data was firstly evaluated against the ground rain gauge observations. The statistical characteristics between a short period data series （1998-2013） and a long period data series （1961-2013） were then compared. The TMPA 3B42V7-based SPI （Standardized Precipitation Index） sequences were finally validated and analyzed at various temporal scales for assessing the drought conditions. The results indicate that the monthly TMPA 3B42V7 precipitation is in a high agreement with the rain gauge observations and can accurately capture the temporal and spatial characteristics of rainfall within the Weihe River Basin. The short period data can present the characteristics of long period record, and it is thus acceptable to use the short period data series to estimate the cumulative probability function in the SPI calculation. The TMPA 3B42V7-based SPI matches well with that based on the rain gauge observations at multiple time scales （i.e., 1-, 3-, 6-, 9-, and 12-month） and can give an acceptable temporal distribution of drought conditions. It suggests that the TMPA 3B42V7 precipitation data can be used for monitoring the occurrence of drought in the Weihe River Basin.

A SYSTEMATIC STUDY ON LAND AND REGIONAL DEVELOPMENT OF THE TARIM RIVER DRAINAGE BASIN,XINJIANG PROVINCE,CHINA

A Systematic Study on Land (SSL), aiming at the investigation of the land complex, isone of the important parts of integrated physical geography. With systematic theory as guid-ance, the dissertaton carries out the comprehensive and systematic study of a series ofsubsystems like land classification, land structure analysis, comprehensive physicalregionalization, land evaluation, reasonable planning of land utilization as well as popula-

Drainage Basin Characteristics of Dhund River Basin, Eastern Rajasthan India, Using Remote Sensing and GIS Techniques

Morphometric analysis is mathematical evaluation and measurement of the earth’s shape, surface and its landform’s dimension. Morphometric analysis of Dhund river basin in Jaipur district of Rajasthan India has been carried out to evaluate various morphometric parameters following the linear, areal and relief aspects. The drainage basin, which covers a total area of about 1828 km2 lies in eastern part of the district with maximum and minimum elevation of 603 m and 214 m respectively. Morphotectonic parameters like Hypsometric Integral, Sinuosity index and Asymmetry Factor have also been computed to identify the tectonic characteristics of the drainage basin. Primary and secondary data such as SOI topographic map, Cartosat-1 DEM and other relevant data were utilized. ArcGIS software (Arc Map 10.2) was used for geo-referencing of topographic maps, delineation of watershed and preparation of DEM, slope and drainage network. The basin is 6th order drainage basin having dendritic pattern of drainage network. A relatively lower mean value of Bifurcation ratio suggests that the drainage basin is formed by uniformed materials. Drainage basin area has little elongated shape and is less prone to floods. Basin has different erosional stages and levels of tectonic activity, Moderate Meandering and unstable setting.

How a New Cenozoic Geology and Glacial History Paradigm Explains Arkansas-Red River Drainage Divide Area Topographic Map Evidence in and near Pontotoc County, Oklahoma, USA

A new Cenozoic geology and glacial history paradigm (new paradigm), fundamentally different from the accepted Cenozoic geology and glacial history paradigm (accepted paradigm), describes a thick North American continental icesheet (located where continental icesheets are usually reported to have been) which by deep erosion and uplift of surrounding regions created and occupied a deep “hole” (the accepted paradigm does not see this thick ice sheet or the deep “hole”). Unusual erosional landform features in the southeast Oklahoma Pontotoc County region including the asymmetric Canadian-Red River drainage divide, a large escarpment-surrounded basin in which most south-oriented Clear Boggy Creek headwaters begin, and a large escarpment-surrounded upland on which the south-oriented Blue River begins, are used to test the new paradigm’s ability to use large and prolonged south-oriented melt water floods to explain previously unexplained or poorly explained detailed topographic map drainage system and erosional landform evidence. Numerous low points (referred to as divide crossings) indicate large and prolonged south-oriented melt water floods did flow across what is now the Canadian-Red River drainage divide (an interpretation also consistent with Clear Boggy Creek escarpment-surrounded basin and Blue River escarpment-surrounded upland shapes). The new paradigm described massive and prolonged melt water floods also account for previously unrecognized deep regional erosion (which is determinable from detailed topographic map evidence). East-oriented Canadian River valley headward erosion (from the Arkansas River valley) diverted the long-lived south-oriented meltwater floods to the Arkansas River valley and to what ultimately became the deep “hole’s” only southern exit. Previous southeast Oklahoma drainage history interpretations (made from the accepted paradigm perspective in which Rocky Mountain glacier melt water flowed to east-oriented rivers) do not provide adequate water volumes or flow directions to explain the detailed topographic map drainage system and erosional landform evidence, which the new paradigm’s massive and prolonged south-oriented melt water floods do explain.

Land Use Land Cover Dynamics of Upper Benue River Basin, Nigeria

This study examined land use land cover (LULC) dynamics in Upper Benue River Basin, Nigeria. The study makes use of primary and secondary data. Landsat Imageries for the years 1981, 2001 and 2021 were used in the study. Supervised approach with maximum likelihood classifier was adopted for the classification and generation of LULC maps. Markov Cellular Automata model was used to predict the status of LULC of the catchment for year 2070. The findings of the study reveal remarkable changes in the land use land cover of the Upper Benue River Basin. The land cover has witnessed downward trend in the percentage area covered by vegetation and bare surface resulting in 15.4% and 2.6% losses respectively. The result of the findings reveals that the built-up area and rock outcrop has shown significant gains of 15.2% and 2.9% of the study area respectively. Water body has been stable with 0% change, though, it witnessed a marginal decline in 2001. The land use land cover change observed in the Upper Benue River Basin was as a result of anthropogenic factors characterized by deforestation, expansion of agricultural lands, overgrazing among others. Based on the findings, the study recommended controlled grazing activity, deforestation and indiscriminate fuelwood exploitation and improved agronomic practices in the basin.

Research on Drainage Network Extraction in Liaohe Basin Based on SRTM DEM and ASTER GDEM

In this study,SRTM DEM data and ASTER GDEM data were used as the basic topographic data,and Arc Hydro Tools was utilized for extension module so as to study on extracting digital drainage network of watershed based on surface runoff model,as well as to compare the two extracted results.The result showed that through the introduction of drainage density parameter to determine the river drainage area threshold,the both extracted drainages showed the goodness-of-fit with the factual drainage network on 1∶250 000 scale topographic map,and the extracted digital river could be used in practical operation of the risk assessment model of mountain torrents disaster in Liaohe basin.

FACILITATING REGIONAL SUSTAINABLE DEVELOPMENT THROUGH INTEGRATED MULTI-OBJECTIVE UTILIZATION, MANAGEMENT OF WATER RESOURCES IN THE LANCANG-MEKONG RIVER BASIN

The Lancnag Mekong River is the most important international river across China and Southeast Asia, If it is developed according to 'Great Mekong Subregional Cooperation Plan' [9] prepared by ADB, the area directly affected will be up to over 2.32 million km 2, the population over 220 million, and the natural environment, and socio-economic conditions within a large area will be greatly changed. 'Agreement on Cooperation for Sustainable Development of Mekong Basin' signed by the four riparian countries along the lower Mekong River on April 5, 1995 provides a new opportunity for sustainable development of the Basin. According to preliminary analysis, if the multipurpose utilization of the water resources is the target for carrying out integrated planning and management, and the efforts are made 1) to focus on energy exploitation on the Lancang River Mainstream and the tributaries of the lower Mekong River; 2) to build gated weirs at Tonle Sam; 3) to construct spillways at the Mekong Delta; 4) to facilitate flood dykes in big cities and on both banks of the mainstream which are concentrated with population and farmland and liable to be flooded, and 5) to strengthen networks for forecasting hydrological and meteorological conditions, then all problems such as power demand, irrigation, flood, salt water intrusion as well as acid water erosion to soil could be solved without constructing large cascaded stations and dams on the lower Mekong Mainstream. This will not only avoid input of great number of fund, large scale resettlement and land inundation, but also prevent aquatic organisms living in Mekong River from being injured due to dam construction, and promote the sustainable development of the Basin.

A decade of variation of COD in the Changjiang River (Yangtze River) and its variation trend analysis

The average annual value of COD (chemical oxygen demand) fluxes of the Changjiang River (Yangtze River) and its main tributaries in the past decade (i.e., 1991–2000), has been evaluated. Based on the data from the Datong Hydrological Station (DHS), it was found that the Dongting Lake drainage basin contributed the greatest water discharge (35.8%) and COD flux (48.3%) among the main tributary drainage basins, followed by the Poyang Lake drainage basin with the contributions of 15.4% and 19.3%,respectively. By the end of the year of 2000, COD flux in the Changjiang River rose by almost 45% relative to that in the year of 1991, reaching about 1941000 ton/a at DHS. Statistical analysis revealed that industrial wastewater discharge, as well as COD in it, was found decreasing in the same period, due to the gradual reinforcement of environmental management. Moreover, correlation analysis indicated that non-point pollution from agriculture and increasing discharge of domestic sewages caused by rapid growth of population along the Changjiang River drainage valley should be responsible for the high COD. Furthermore, with the current trend of population growth and agricultural development in this basin, water quality of the Changjiang River, in terms of COD level, is going to deteriorate in the near future. Thus, the rational applications of fertilizers and pesticides in agriculture and the proper treatment of domestic sewages before they are discharged would be the most concerned controlling parameters.

Multi-Fractal Characteristics of Daily Runoff Series of Weihe River Watershed

Application of fractal theory on the evolution of nonlinear study of the hydrological system, which found its internal rules from the complex hydrologic system, could make us more fully understand the hydrodynamic characteristics of the complex motion of this system. Taking Weihe River as study area, this paper analyzes daily runoff series’ multi-fractal character and relative fluctuation feature by using the De-trended Fluctuation Analysis (DFA) method. Result shows that the daily runoff series of main channel and branches of Weihe river all shows multi-fractal characteristics clearly, and the turns of multi-fractal intensity of daily runoff series in Weihe river are: Xianyang station (1.388) > Yingge station (0.697) > Linjiacun station (0.665) > Zhangjiashan station (0.662) > Zhuangtou station (0.635). Rainfall, evaporation, water income and human activity and other factors affect the fluctuation character and multi-fractal intensity of daily runoff series through these factors’ superimposition and pining down mutually. This study could provide a theoretical supply for obtaining the quantitative indicators on multi-fractal characteristics about eco-environment situation of watershed, and for runoff forecasting.

The Spatio-temporal Evolution of Ecological Risk and Its Drivers in the Weihe River Basin Landscape from 1990 to 2020

The Weihe River Basin has a significant number of tributaries and a delicate ecological environment.Understanding the spatial and temporal evolution and determinants of landscape ecological risk in the Weihe River Basin(WRB)can improve the scientific protection and development of its watershed ecosystems.This study is based on land use statistics from the WRB for a 30-year period represented by 1990,2000,2010,and 2020.An initial model for the assessment of landscaping ecological hazards was created using the software that was also used to generate the landscape ecological risk index,such as ArcGIS 10.4 and Fragstats 4.2-64.Next,the spatial and temporal evolution of landscape ecological risk in the vicinity of the study area was characterized by the trajectory of the center of gravity migration and the spatial autocorrelation of GeoDa.Finally,Geodetector was used to analyze ecological risk drivers in the landscapes.According to the findings,the high-risk and relatively high-risk regions are steadily expanding,while the low-risk and relatively low-risk areas dominate the ecological risk landscape in the WRB.Within the Weihe River Basin,Xianyang and Xi'an are the areas to which the high-risk centers of gravity are migrating.Positive spatial correlations were found between the landscape ecological hazards in the study area,most prominently in the form of high-high and low-low aggregations.The primary drivers are the interplay between the GDP component,temperature,and elevation as a single factor.

Analyzing Anomalous Topographic Map Drainage System and Landform Evidence as a Glacial History Paradigm Problem: A Literature Review

While not usually stated, detailed topographic maps show well-mapped anomalous drainage system and other erosional landform evidence the accepted North American Cenozoic geologic and glacial history paradigm (accepted paradigm) does not permit geomorphologists to satisfactorily explain. A new and fundamentally different paradigm able to explain the drainage system and other erosional landform evidence has recently emerged, but requires what the accepted paradigm considers to be the preglacial (and probably mid-Cenozoic) Bell River drainage system to have formed on a melting continental ice sheet’s floor. The new paradigm’s melting ice sheet had previously eroded bedrock underneath it and caused crustal warping that raised continental regions and mountain ranges so as to create and occupy a deep “hole” while massive and prolonged meltwater floods flowed across rising continental regions and mountain ranges to the south. The new paradigm leads to a completely different middle Cenozoic geologic and glacial history than the accepted paradigm describes and the two paradigms are analyzed according to good science expectations such as using evidence anyone can see, applying common sense logic during each research step, producing consistent results, and simplicity of paradigm generated explanations. The new paradigm uses topographic map evidence anyone can see, appears to use common sense logic during each research step, and produces remarkably consistent results leading to a simpler Cenozoic northern Missouri River drainage basin region geologic and glacial history than what the accepted paradigm describes. Further work is needed to test the new paradigm’s ability to explain drainage system and erosional landform evidence in other geographic regions such as in the Ohio River drainage basin.

Occurrence and distribution of hexabromocyclododecane in sediments from seven major river drainage basins in China

The concentrations and geographical distribution of hexabromocyclododecane （HBCD） were investigated in 37 composite surface sediments from seven major river drainage basins in China, including Yangtze River, Yellow River, Pearl River, Liaohe River, Haihe River, Tarim River and Ertix River. The detection frequency of HBCD was 54%, with the concentrations ranged from below limit of detection （LOD） to 206 ng/g dry weight. In general, the geographical distribution showed increasing trends from the upper reaches to the lower reaches of the rivers and from North China to Southeast China. Compared to other regions in the world, the average concentration of HBCD in sediments from Yangtze River drainage basin was at relatively high level, whereas those from other six river drainage basins were at lower or similar level. The highest HBCD concentration in sediment from Yangtze River Delta and the highest detection frequency of t-IBCD in Pearl River drainage basins suggested that the industrial and urban activities could evidently affect the HBCD distribution. HBCD diastereoisomer profiles showed that y-HBCD dominated in most of the sediment samples, followed by ct- and [3-HBCD, which was consistent with those in the commercial HBCD mixtures. Further risk assessment reflected that the average inventories of HBCD were 18.3, 5.87, 3.92, 2.50, 1.77 ng/cm2 in sediments from Pearl River, Haihe River, Tarim River, Yellow River and Yangtze River, respectively.