Oxygen Regime of the Channel Flow in the Small Maima River,Upper Ob Basin

Water Resources - The oxygen regime of the channel flow of the small Maima River (Upper Ob basin) has been considered. A study of the spatial and seasonal variations of oxygen regime...     

Assessment of Influences of Anthropogenic and Climatic Changes in the Drainage Basin on Hydrological Processes in the Gulf of Ob

Water Resources - Changes in the runoff of rivers flowing into the Arctic Ocean caused by climate changes and increasing anthropogenic load lead to foreseeable transformations of hydrological...     

Simulating Groundwater-Streamflow Connections in the Upper Colorado River Basin

In mountain, snow driven catchments, snowmelt is supposed to be the primary contribution to river streamflows during spring. In these catchments the contribution of groundwater is not well documented because of the difficulty to monitor groundwater in such complex environment with deep aquifers. In this study we use an integrated hydrologic model to conduct numerical experiments that help quantify the effect of lateral groundwater flow on total annual and peak streamflow in predevelopment conditions. Our simulations focus on the Upper Colorado River Basin (UCRB; 2.8 × 10⁵ km²) a well-documented mountain catchment for which both streamflow and water table measurements are available for several important sub-basins. For the simulated water year, our results suggest an increase in peak flow of up to 57% when lateral groundwater flow processes are included—an unexpected result for flood conditions generally assumed independent of groundwater. Additionally, inclusion of lateral groundwater flow moderately improved the model match to observations. The correlation coefficient for mean annual flows improved from 0.84 for the no lateral groundwater flow simulation to 0.98 for the lateral groundwater flow one. Spatially we see more pronounced differences between lateral and no lateral groundwater flow cases in areas of the domain with steeper topography. We also found distinct differences in the magnitude and spatial distribution of streamflow changes with and without lateral groundwater flow between Upper Colorado River Sub-basins. A sensitivity test that scaled hydraulic conductivity over two orders of magnitude was conducted for the lateral groundwater flow simulations. These results show that the impact of lateral groundwater flow is as large or larger than an order of magnitude change in hydraulic conductivity. While our results focus on the UCRB, we feel that these simulations have relevance to other headwaters systems worldwide.     

Hydrological impacts of climate change on rice cultivated riparian wetlands in the Upper Meghna River Basin (Bangladesh and India)

ABSTRACT

Riparian depressional wetlands (haors) in the Upper Meghna River Basin of Bangladesh are invaluable agricultural resources. They are completely flooded between June and November and planted with Boro rice when floodwater recedes in December. However, early harvest period (April/May) floods frequently damage ripening rice. A calibrated/validated Soil and Water Assessment Tool for riparian wetland (SWATrw) model is perturbed with bias free (using an improved quantile mapping approach) climate projections from 17 general circulation models (GCMs) for the period 2031–2050. Projected mean annual rainfall increases (200–500 mm or 7–10%). However, during the harvest period lower rainfall (21–75%) and higher evapotranspiration (1–8%) reduces river discharge (5–18%) and wetland inundation (inundation fraction declines of 0.005–0.14). Flooding risk for Boro rice consequently declines (rationalized flood risk reductions of 0.02–0.12). However, the loss of cultivable land (15.3%) to increases in permanent haor inundation represents a major threat to regional food security.     

New magnetic and paleomagnetic data from the Volodarka section (the Ob River)

New magnetic and paleomagnetic data from the loess-soil Volodarka section (the Ob River) are presented. In particular, a secondary magnetization aligned with the contemporary magnetic field and persisting on heating to 500–600°C is shown to be present. It is shown that the transition zone of the Matuyama-Brunhes reversal is most likely located within the soil complex, consisting of three paleosol horizons separated by two horizons of loesslike loam that belong to the same interglaciation.     

Organic Trace Components Extractable by Chloroform from Swamp and River Waters in the Middle Ob Basin

For the first time in the Middle Ob Basin, new data of importance for evaluating the quality of swamp and river water were obtained, characterizing the microcomponent composition of extractive organic compounds. More than 150 compounds of natural genesis were identified. The water of oligotrophic and mesotrophic bogs shows widest diversity and maximal, almost equal masses of extractable organic substances, averaging 13357 ng/L. In the water of eutrophic bogs and taiga rivers, this characteristic is five times lower; and that in lakes is lower by more than an order of magnitude. The amount of extractive trace components is closely correlated with the concentration of water-soluble carbon of humic nature. It was established that the natural water of taiga zone identical in terms of the fulvate type differs in the composition of organic trace components and can be grouped into four clusters: (a) water of oligotrophic bogs, (b) water of mesotrophic bogs, (c) river water, and (d) water of eutrophic bogs and bog lakes.     

Anthropogenic changes in phytoplankton in lakes of the Kenti River system (Republic of Karelia)

The article presents the results of phytoplankton observations in lakes of the Kenti River system, which have been long subjected to the anthropogenic impact of processing wastewaters from the Kostomuksha Mining and Processing Works. Specific features of changes in the abundance and biomass of different systematic groups of phytoplankton as well as dimensional and species structure of phytoplankton communities are discussed. These changes are caused by the intensification of anthropogenic impact on lake ecosystems, in particular, by an increase in water mineralization and its content of biogenic substances, as well as by changes in the ion composition of water.     

非点源污染对太湖上游西苕溪流域水环境的影响

水资源短缺是全球性关注的问题,水质恶化更加剧了这一问题的严重性,定量研究水质变化及其影响凶素可为治理水环境提供基础依据．与实测数据及综合污染指数的对比表明,水质指数能够合理反映水质的变化程度和时空变化趋势．利用西苕溪流域1996-2000年水质监测数据的研究结果如下：西苕溪流域水质的空间变化趋势是自上游至下游逐渐恶化,时间变化的总体趋势是逐年转好;点污染源得到有效控制年份(1999年)的水质指数比以前年份(1996-1998年)有所提高但幅度不大,说明非点源污染是影响西苕溪流域水质的重要因素;流域水污染的主要形式是氮、磷污染,其主要非点源是农田、经济竹林和城镇径流及居民生活污水等．     

武汉市南湖大型底栖动物的群落结构

在分析企业环境行为类型及决策机制的基础上,认为内外环境因素的综合作用促成了企业环境行 为的发生．据此,通过相关性和主成分分析对太湖流域印染企业环境行为影响因素进行选择,并构建了环 境行为决策数量模型,结果表明：私营合资企业环保投入水平高于国有集体企业;中型企业环保投入高于小 型企业,此外,企业环境行为演变也受政府和经济环境制约．最后提出了优化企业环境行为的对策,即加快 企业改制,强化用地供应管理,改革排污费制度以及规划产业布局．     

Changes in Projected Spatial and Seasonal Groundwater Recharge in the Upper Colorado River Basin

The Colorado River is an important source of water in the western United States, supplying the needs of more than 38 million people in the United States and Mexico. Groundwater discharge to streams has been shown to be a critical component of streamflow in the Upper Colorado River Basin (UCRB), particularly during low‐flow periods. Understanding impacts on groundwater in the basin from projected climate change will assist water managers in the region in planning for potential changes in the river and groundwater system. A previous study on changes in basin‐wide groundwater recharge in the UCRB under projected climate change found substantial increases in temperature, moderate increases in precipitation, and mostly periods of stable or slight increases in simulated groundwater recharge through 2099. This study quantifies projected spatial and seasonal changes in groundwater recharge within the UCRB from recent historical (1950 to 2015) through future (2016 to 2099) time periods, using a distributed‐parameter groundwater recharge model with downscaled climate data from 97 Coupled Model Intercomparison Project Phase 5 (CMIP5) climate projections. Simulation results indicate that projected increases in basin‐wide recharge of up to 15% are not distributed uniformly within the basin or throughout the year. Northernmost subregions within the UCRB are projected an increase in groundwater recharge, while recharge in other mainly southern subregions will decline. Seasonal changes in recharge also are projected within the UCRB, with decreases of 50% or more in summer months and increases of 50% or more in winter months for all subregions, and increases of 10% or more in spring months for many subregions.     

Quantifying Climatic and Anthropogenic Influences on Water Discharge and Sediment Load in Xiangxi River Basin of the Three Gorges Reservoir Area

Water Resources - Quantifying the relative contributions of climate change and human activities to water and sediment variations is of great importance for regional resources and river basin...     

On the paleomagnetism of loesses and correlation of the Belovo and Volodarka sections (the Ob River Region)

A new correlation scheme is proposed for the Belovo and Volodarka loess-soil sections on the basis of the author’s paleomagnetic studies. It is shown that the paleomagnetic stratigraphy and correlation of sections of the Loess Plateau, China, are not self-consistent. The paper gives recommendations for correct use of the paleomagnetic method in the study of loess sections.     

Assessment of Anthropogenic Impact on River Basins in Southern Kuzbass Mining Areas

The total pollution caused by spreading and fallout of atmospheric aerosols in river catchment areas of a coal-mining region is estimated. The contribution of the emission produced by a coal mine to the total fallout in the territory is assessed. Different types of water pollution in the coal-mining region are analyzed, the principal pollutants are identified, and their contribution to river water quality is assessed.     

Pollution effects of the Tuy River on the central Venezuelan coast: Anthropogenic organic compounds and heavy metals in Tivela mactroidea

Bivalve samples were collected at seven sampling stations located between the town of Machurucuto and the Bay of Higuerote, Venezuela, covering approximately 70 km of coastline. Samples were collected both east and west of the Tuy River mouth, which has a plume known to move in a north-westerly direction. Petroleum hydrocarbons, both aliphatic (n-alkanes and UCM) and polyaromatic (PAHs), were detected and quantified in the samples. These hydrocarbons were found to be primarily derived from fossil fuels. Halogenated organics consisted mostly of polychlorinated biphenyls (PCBs) and some chlorinated pesticides, primarily of the DDT group. Heavy metals such as Pb, Cu, Ni, Zn, Cr and Cd were analysed in the samples. The results clearly show the influence of the Tuy River plume on the water quality of the coastal zone, particularly that located west of the river mouth. One sampling station, located just east of the river mouth, also showed significant influence from the river plume.     

草型湖泊和藻型湖泊中大型底栖动物群落结构的比较

系统地比较了草型湖泊扁担塘与藻型湖泊后湖大型底栖动物的群落结构.结果表明,草型湖泊扁担塘的物种种类、物种多样性、密度和生物量均较藻型湖泊后湖的为高.两湖在物种组成和功能摄食群上存在极大差异,相似性系数为0.3左右,草型湖泊的大型底栖动物主要以刮食者数量为多,而藻型湖泊主要以收集者的为多.这说明水生高等植物对于维持湖泊生态系统中大型底栖动物多样性方面起着非常重要的作用,也是维持湖泊生态系统结构复杂性、空间异质性和功能稳定性的重要因素.     

Sensitivity of the Penman-Monteith reference evapotranspiration to sunshine duration in the Upper Mekong River Basin

Sensitivity analysis is important in understanding the relationship between sunshine duration (SD) and reference evapotranspiration (ET_ref). This study was developed in the Lancang-Mekong River Basin using a non-dimensional relative sensitivity coefficient (S_N) relating ET_ref to SD. The S_N for January and July for each station were calculated. The results indicate that (a) the SD and S_N change in similar ways, where January and July are selected as two representative time slices; (b) the spatial distributions of the long-term averaged S_N for January and July are the reverse of each other; (c) the most abrupt changes in climate occur in the 1980s and the middle region is sensitive to climate change; and (d) periodicities of 2–4 and 14–16 years are detected in the basin generally. The significant increase of inter-decadal filter variance indicates changes in the long-term memory of the local climate system.

EDITOR Z.W. Kundzewicz

ASSOCIATE EDITOR not assigned     

The role of baseflow in dissolved solids delivery to streams in the Upper Colorado River Basin

Salinity has a major effect on water users in the Colorado River Basin, estimated to cause almost $300 million per year in economic damages. The Colorado River Basin Salinity Control Program implements and manages projects to reduce salinity loads, investing millions of dollars per year in irrigation upgrades, canal projects, and other mitigation strategies. To inform and improve mitigation efforts, there is a need to better understand sources of salinity to streams and how salinity has changed over time. This study explores salinity in the baseflow fraction of streamflow, assessing whether groundwater is a significant contributor of dissolved solids to streams in the Upper Colorado River Basin (UCRB). Chemical hydrograph separation was used to estimate baseflow discharge and baseflow dissolved solids loads at stream gages (n = 69) across the UCRB. On average, it is estimated that 89% of dissolved solids loads originate from the baseflow fraction of streamflow, indicating that subsurface transport processes play a dominant role in delivering dissolved solids to streams in the UCRB. A statistical trend analysis using weighted regressions on time, discharge, and season was used to evaluate changes in baseflow dissolved solids loads in streams (n = 27) from 1986 to 2011. Decreasing trends in baseflow dissolved solids loads were observed at 63% of streams. At the three most downstream sites, Green River at Green River, UT, Colorado River at Cisco, UT, and the San Juan River near Bluff, UT, baseflow dissolved solids loads decreased by a combined 823,000 metric tons (mT), which is approximately 69% of projected basin‐scale decreases in total dissolved solids loads as a result of salinity control efforts. Decreasing trends in baseflow dissolved solids loads suggest that salinity mitigation projects, landscape changes, and/or climate are reducing dissolved solids transported to streams through the subsurface. Notably, the pace and extent of decreases in baseflow dissolved solids loads declined during the most recent decade; average decreasing loads during the 2000s (28,200 mT) were only 54% of average decreasing loads in the 1990s (51,700 mT).     

东江流域典型子流域土地利用/覆被变化对地表径流影响

应用SWAT模型对东江上中下游典型流域的地表径流进行模拟,采用1977 - 1981年和1996-2000年胜前、顺天和九州三个出口控制站逐月实测径流资料进行模型校准和验证,确定模型的敏感性参数,采用相关系数R2和Nash-Suttclife模型效率系数ENS,对SWAT模型模拟结果进行评价,结果显示模拟精度较高,R2...