scholarly journals Catchment landscape components alter relationships between discharge and stream water nutrient ratios in the Xitiao River Basin China

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Changjun Gao ◽  
Wei Li ◽  
Lijuan Cui ◽  
Qiongfang Ma ◽  
Jian Cai
Keyword(s):  
River Basin ◽  
Urban Areas ◽  
Stream Water ◽  
Hydrological Regime ◽  
Low Flow ◽  
Nutrient Ratios ◽  
Terrestrial Environment ◽  
Discharge Data ◽  
Stream Discharge ◽  
C:P Ratios

AbstractThe terrestrial environment of a watershed is a source of potential carbon (C), nitrogen (N), and phosphorus (P) exports, and the hydrological regime provides the mechanism to turn the potential exports into reality when water is available. However, the extent to which the terrestrial environment alters the strength and nature of streamflow in transporting stream water nutrient ratios remains largely unknown. This study combined monthly stream discharge data with synchronously sampled stream water C:N:P ratios in 14 catchment streams in the Xitiao River Basin (XRB) in Zhejiang Province, China. The transport effect of streamflow on C:N:P ratios varied depending on the nutrient element, flow condition, and terrestrial environment. In the lower reaches of the XRB, there were negative relationships between C:N ratios, C:P ratios and watershed discharge, and positive relationships between N:P ratios and watershed discharge in both high and low flow conditions. In the middle and upper reaches of the XRB, the C:N-discharge relationship changed from negative to positive when the streamflow conditions altered from low to high flow. The C:P- and N:P-discharge relationships were negative regardless of high or low flows, but the regression coefficient significantly decreased with increasing streamflow. The C:N-discharge correlation over the course of the year shifted from negative to positive, as urban areas expanded within the catchment. The C:P-discharge relationship altered from negative to positive with more cropland and wetland but from positive to negative with a greater forest percentage and mean percentage slope. Our results indicate that changes in the terrestrial environment (e.g., the proportion of a particular land cover within a watershed) generally produced a threshold flow above which the coupling relationships between element fluxes from the terrestrial to riverine ecosystem changed sharply.

Changes in Latvian river discharge regime at the turn of the century

2012 ◽  
Vol 44 (3) ◽  
pp. 554-569 ◽  
Author(s):  
Elga Apsīte ◽  
Ilze Rudlapa ◽  
Inese Latkovska ◽  
Didzis Elferts
Keyword(s):  
River Runoff ◽  
River Discharge ◽  
Large Scale ◽  
Hydrological Regime ◽  
Turn Of The Century ◽  
Significant Trend ◽  
Low Flow ◽  
Data Series ◽  
Discharge Data ◽  
Baltic Countries

The study deals with turn-of-the-century changes in the total annual river runoff distribution and high and low flows in Latvia, covering river basins within four hydrological districts which vary according to size and physiographical conditions. Mathematical statistical methods were applied in the analysis of river discharge data series for two study periods of 1951–2009 and 1881–2009. The present results confirm the basic statement concerning the Baltic countries that major significant changes in river runoff during the last two decades have occurred between spring (decrease) and winter (increase) seasons. Mostly insignificant changes in summer runoff and significant/insignificant changes in autumn runoff were found. Analysis shows that a statistically significant trend of increase in low flow for the cold period and a significant trend of decrease in the high discharge and coefficient d of uneven runoff distribution were detected. Changes in river hydrological regime are mainly caused by changes in large-scale atmospheric circulation processes following climate warming, which has taken place. Latvian river hydrography has therefore changed and become more similar to Western European rivers.

Physiographic controls on pre-event hydrological states and hydrological response to extreme precipitation in the Alzette River Basin, Luxembourg

2020 ◽  
Author(s):  
Carol Tamez-Melendez ◽  
Judith Meyer ◽  
Audrey Douinot ◽  
Günter Blöschl ◽  
Laurent Pfister
Keyword(s):  
Land Use ◽  
River Basin ◽  
Urban Areas ◽  
Large Scale ◽  
Western Europe ◽  
Flash Flood ◽  
Potential Evapotranspiration ◽  
Hydrological Regime ◽  
Area Of Interest ◽  
Wide Range

<p>The hydrological regime of rivers in Luxembourg (Central Western Europe) is characterised by summer low flows and winter high flows. In winter, large-scale floods are typically triggered by long-lasting sequences of precipitation events, related to westerly atmospheric fluxes that carry wet and temperate air masses from the Atlantic Ocean. In recent years, several flash flood events have been observed in Luxembourg. While being a common feature of Mediterranean river basins, this type of flooding events is uncommon at higher latitudes. The design of the hydro-meteorological monitoring and forecasting systems operated in Luxembourg is not adapted to this type of extreme events and there is a pressing need for a better mechanistic understanding of flash flood triggering mechanisms.</p><p>Here, we explore two lines of research – focusing on (i) the spatio-temporal variability of flash flood generation across a set of 41 nested catchments covering a wide range of physiographic settings (with mixed land use, soil types and bedrock geology) and (ii) the responsivity (resistance) and elasticity (resilience) of these catchments to global change.</p><p>Our area of interest is the Sûre River basin (4,240 km<sup>2</sup>), characterised by a homogenous climate (temperate oceanic), as well as various bedrock (e.g. sandstone, marls, shale) and land use (e.g. forests, grassland, crops, urban areas) types. Based on 8 years’ worth of daily hydrological data (precipitation, discharge and potential evapotranspiration) we computed the increments of the water balance to determine the maximum storage capacity and pre-event wetness state (expressed as storage deficit). Based on the relationship between storage deficit and discharge we first estimated total storage at nearly zero flow conditions. Second, we compared event runoff ratios (Q/P) to pre-hydrological states (as expressed to storage deficit prior to a rainfall-runoff event) in order to assess each catchment’s sensitivity to antecedent wetness conditions. Third, we assessed the responsivity (resistance) and elasticity (resilience) to climate variations – as expressed through the PET/P and AET/P deviations from the Budyko curve – for each individual catchment. Finally, we investigated potential physiographic controls on catchment responsivity and elasticity across our set of 41 nested catchments.</p>

scholarly journals Mean Transit Times in Headwater Catchments: Insights from the Otway Ranges, Australia

2017 ◽  
Author(s):  
William Howcroft ◽  
Ian Cartwright ◽  
Uwe Morgenstern
Keyword(s):  
Stream Water ◽  
Anthropogenic Activities ◽  
Discharge Data ◽  
Headwater Catchments ◽  
Stream Discharge ◽  
Lumped Parameter ◽  
Transit Times ◽  
Lumped Parameter Models ◽  
Bush Fire ◽  
Major Ion Geochemistry

Abstract. Understanding the timescales of water flow through catchments and the origins of stream water at different flow conditions is critical for understanding catchment behaviour and managing water resources. Here, tritium (3H) activities, major ion geochemistry and discharge data were used in conjunction with Lumped Parameter Models (LPMs) to investigate mean transit times (MTTs) and the stores of water in six headwater catchments of the Otway Ranges in southeast Australia. 3H activities of stream water ranged from 0.20 to 2.14 TU, which are far lower than those of modern local rainfall (2.4 to 3.2 TU). The 3H activities of the stream water are lowest during the low summer flows and increase with stream discharge. Calculated MTTs vary from approximately 7 to 234 years which, in many cases, exceed those reported for river systems globally. The MTT estimates, however, are subject to a number of uncertainties, including, uncertainties in the most appropriate LPM to use, aggregation errors, and uncertainty in the modern and bomb-pulse 3H activity of rainfall. These uncertainties locally result in uncertainties in MTTs of several years; however, they do not change the overall conclusions that the water in these streams has MTTs of several years to decades. There is discharge threshold of approximately 104 m3 day−1 in all catchments above which 3H activities do not increase appreciably above ~ 2.0 TU. The MTT of this 3H activity is approximately ten years, which implies that changes within the catchments, including drought, deforestation, land use and/or bush fire, would not be realised within the streams for at least a decade. A positive correlation exists between 3H activities and nitrate and sulphate concentrations within several of the catchments, which suggests that anthropogenic activities have increasingly impacted water quality at these locations over time.

scholarly journals Impact of Climate Change on the Hydrological Regime of the Yarkant River Basin, China: An Assessment Using Three SSP Scenarios of CMIP6 GCMs

2021 ◽  
Vol 14 (1) ◽  
pp. 115
Author(s):  
Yanyun Xiang ◽  
Yi Wang ◽  
Yaning Chen ◽  
Qifei Zhang
Keyword(s):  
Climate Change ◽  
River Basin ◽  
Bias Correction ◽  
Hydrological Regime ◽  
Low Flow ◽  
Future Climate Change ◽  
Climate Projections ◽  
Climate Change Scenarios ◽  
Near Future ◽  
Far Future

Quantification of the impacts of climate change on streamflow and other hydrological parameters is of high importance and remains a challenge in arid areas. This study applied a modified distributed hydrological model (HEC-HMS) to the Yarkant River basin, China to assess hydrological changes under future climate change scenarios. Climate change was assessed based on six CMIP6 general circulation models (GCMs), three shared socio-economic pathways (SSP126, SSP245, SSP370), and several bias correction methods, whereas hydrological regime changes were assessed over two timeframes, referred to as the near future (2021–2049) and the far future (2071–2099). Results demonstrate that the DM (distribution mapping) and LOCI (local intensity scaling) bias correction methods most closely fit the projections of temperature and precipitation, respectively. The climate projections predicted a rise in temperature of 1.72–1.79 °C under the three SSP scenarios for the near future, and 3.76–6.22 °C under the three SSPs for the far future. Precipitation increased by 10.79–12% in the near future, and by 14.82–29.07% during the far future. It is very likely that streamflow will increase during both the near future (10.62–19.2%) and far future (36.69–70.4%) under all three scenarios. The increase in direct flow will be greater than baseflow. Summer and winter streamflow will increase the most, while the increase in streamflow was projected to reach a maximum during June and July over the near future. Over the far future, runoff reached a peak in May and June. The timing of peak streamflow will change from August to July in comparison to historical records. Both high- and low-flow magnitudes during March, April, and May (MAM) as well as June, July, and August (JJA) will increase by varying degrees, whereas the frequency of low flows will decrease during both MAM and JJA. High flow frequency in JJA was projected to decrease. Overall, our results reveal that the hydrological regime of the Yarkant River is likely to change and will be characterized by larger seasonal uncertainty and more frequent extreme events due to significant warming over the two periods. These changes should be seriously considered during policy development.

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