scholarly journals A Stable Isotope Approach for Estimating the Contribution of Recycled Moisture to Precipitation in Lanzhou City, China

Water ◽  
2021 ◽  
Vol 13 (13) ◽  
pp. 1783
Author(s):  
Fenli Chen ◽  
Mingjun Zhang ◽  
Xixi Wu ◽  
Shengjie Wang ◽  
Athanassios A. Argiriou ◽  
...  
Keyword(s):  
Environmental Changes ◽  
Water Cycle ◽  
Summer Precipitation ◽  
Northwest China ◽  
Plant Transpiration ◽  
Surface Evaporation ◽  
Lanzhou City ◽  
Water Vapors ◽  
Spatial Differences ◽  
Dependent Parameter

The proportional contribution of recycled moisture to local precipitation is a geographically dependent parameter that cannot be ignored in water budgets. Stable hydrogen and oxygen isotopes are sensitive to environmental changes and can be applied to investigate the modern water cycle. In this study, a three-component mixing model is used to calculate the contribution of different water vapors (advection, evaporation and transpiration) to summer precipitation in Lanzhou city, Northwest China. The results show that for all sampling sites in Lanzhou, the contribution of advection vapor to precipitation is the largest, followed by the plant transpiration vapor, and the contribution of surface evaporation water vapor is usually the least, with the average values of 87.96%, 9.1% and 2.9%, respectively. The spatial differences of plant transpiration vapor are generally larger than those of advection vapor and surface evaporation vapor, and the high values appear in Yongdeng, Daheng and Gaolan.

scholarly journals New techniques for gap-filling and partitioning of H<sub>2</sub>O and CO<sub>2</sub> eddy fluxes measured over forests in complex mountainous terrain

2017 ◽  
Author(s):  
Minseok Kang ◽  
Joon Kim ◽  
Bindu Malla Thakuri ◽  
Junghwa Chun ◽  
Chunho Cho
Keyword(s):  
Environmental Changes ◽  
Water Cycle ◽  
Co2 Flux ◽  
Test Method ◽  
Co2 Fluxes ◽  
Gap Filling ◽  
New Techniques ◽  
Diameter Increment ◽  
Filling Method ◽  
Rain Events

Abstract. The continuous measurement of H2O and CO2 fluxes using the eddy covariance (EC) technique is still challenging for forests in complex terrain because of large amounts of wet canopy evaporation (EWC), which occur during and following rain events when the EC systems rarely work correctly, and the horizontal advection of CO2 generated at night. We propose new techniques for gap-filling and partitioning of the H2O and CO2 fluxes: (1) a model-stats hybrid method (MSH) and (2) a modified moving point test method (MPTm). The former enables the recovery of the missing EWC in the traditional gap-filling method and the partitioning of the evapotranspiration (ET) into transpiration and (wet canopy) evaporation. The latter determines the friction velocity (u*) threshold based on an iterative approach using moving windows for both time and u*, thereby allowing not only the nighttime CO2 flux correction and partitioning but also the assessment of the significance of the CO2 drainage. We tested and validated these new methods using the datasets from two flux towers, which are located at forests in hilly and complex terrains. The MSH reasonably recovered the missing EWC of 16 ~ 41 mm year−1 and separated it from the ET (14 ~ 23 % of the annual ET). The MPTm produced consistent carbon budgets using those from the previous research and diameter increment, while it has improved applicability. Additionally, we illustrated certain advantages of the proposed techniques, which enables us to understand better how ET responses to environmental changes and how the water cycle is connected to the carbon cycle in a forest ecosystem.

scholarly journals Abundant Precipitation in Qilian Mountains Generated from the Recycled Moisture over the Adjacent Arid Hexi Corridor, Northwest China

Water ◽  
2021 ◽  
Vol 13 (23) ◽  
pp. 3354
Author(s):  
Zhihua Zhang ◽  
Qiudong Zhao ◽  
Shiqiang Zhang
Keyword(s):  
Water Vapor ◽  
Water Cycle ◽  
Precipitable Water ◽  
Northwest China ◽  
Hexi Corridor ◽  
Qilian Mountains ◽  
Mountain Areas ◽  
Reanalysis Dataset ◽  
Weather Forecasts ◽  
Endorheic Basin

The observed precipitation was suggestive of abundant precipitation in upstream Qilian mountains and low precipitation in the downstream oasis and desert in an endorheic basin. However, precipitation in mountains generated from the recycled moisture over oasis and desert areas has rarely been studied. The climatological patterns of water vapor from 1980 to 2017 in the Qilian Mountain Region (QMR) and Hexi Corridor Region (HCR) were investigated by the European Centre for Medium-Range Weather Forecasts Interim reanalysis dataset and the Modern-Era Retrospective Analysis for Research and Application, Version 2 reanalysis dataset. The results suggest that the precipitable water content decreases from the adjacent to the mountain areas. There are two channels that transport water vapor from the HCR to the QMR in the low troposphere (surface—600 hPa), suggesting that parts of recycled moisture generated from evapotranspiration over the oasis and desert of the HCR is transported to the QMR, contributing to the abundant precipitation in the QMR. This indicates that the transport mechanism is probably because of the “cold and wet island effect” of the cryosphere in QMR. This is likely one of the essential mechanisms of the water cycle in endorheic river basins, which has rarely been reported.

scholarly journals Beaver dam capacity of Canada’s boreal plain in response to environmental change

2020 ◽  
Vol 10 (1) ◽  
Author(s):  
Nichole-Lynn Stoll ◽  
Cherie J. Westbrook
Keyword(s):  
Environmental Conditions ◽  
Environmental Changes ◽  
Water Cycle ◽  
Stream Networks ◽  
Stream Network ◽  
Beaver Dam ◽  
Riding Mountain National Park ◽  
Induced Changes ◽  
Response To Environmental Change ◽  
Beaver Dams

Abstract Environmental changes are altering the water cycle of Canada’s boreal plain. Beaver dams are well known for increasing water storage and slowing flow through stream networks. For these reasons beavers are increasingly being included in climate change adaptation strategies. But, little work focuses on how environmental changes will affect dam building capacity along stream networks. Here we estimate the capacity of the stream network in Riding Mountain National Park, Manitoba, Canada to support beaver dams under changing environmental conditions using a modelling approach. We show that at capacity, the park’s stream network can support 24,690 beaver dams and hold between 8.2 and 12.8 million m3 of water in beaver ponds. Between 1991 and 2016 the park’s vegetation composition shifted to less preferred beaver forage, which led to a 13% decrease in maximum dam capacity. We also found that dam capacity is sensitive to the size of regularly-occurring floods—doubling the 2-year flood reduces the park’s dam capacity by 21%. The results show that the potential for beaver to offset some expected climatic-induced changes to the boreal water cycle is more complex than previously thought, as there is a feedback wherein dam capacity can be reduced by changing environmental conditions.

Analysis of the Dominant Spatial Patterns of Summer Precipitation and Circulation Characteristics in Northwest China

2020 ◽  
Author(s):  
liwei liu ◽  
guoyang lu ◽  
dong wei ◽  
danhua li ◽  
xing wang ◽  
...  
Keyword(s):  
North Atlantic ◽  
Summer Precipitation ◽  
Summer Rainfall ◽  
Northwest China ◽  
Diagnostic Methods ◽  
Height Field ◽  
Main Mode ◽  
The North ◽  
Circulation Characteristic ◽  
The North Atlantic

&lt;p&gt;In recent years, the summer rainfall&amp;#160;shows&amp;#160;an&amp;#160;increasing&amp;#160;trend&amp;#160;in&amp;#160;Northwest China. Based on the NCEP/NCAR reanalysis data, the RESST data from NOAA and the precipitation data from 351 meteorological observation stations in Northwest China from 1981-2018, the dominant modes of summer precipitation anomalies, the corresponded circulation characteristic&amp;#160;and the&amp;#160;main&amp;#160;influence&amp;#160;systems&amp;#160;were analyzed by diagnostic methods. There were&amp;#160;three&amp;#160;dominant EOF modes about summer rainfall, the first one&amp;#160;showed the same anomaly in whole region, the second showed a inverse pattern between the east and west, and the third showed the opposite anomaly between the south and north. The variance contribution of the first mode accounted for 20%&amp;#160;and the first mode was represented as the primary mode in the subsequent analysis. The high impact region of circulation&amp;#160;which affected the precipitation in Northwest China was the middle and high latitudes&amp;#160;area of Eurasia&amp;#160;and the subtropical&amp;#160;area: for&amp;#160;the first mode&amp;#8217;s&amp;#160;positive phase, the 500hPa height field showed&amp;#160;a &quot;+ - +&quot; distribution in the middle latitude of Eurasia, while on the 200hPa wind field, there was an anticyclone near the Ural and a cyclone near Lake Baikal, it also has an anticyclone on the Chinese mainland, this configuration will facilitates the strengthening of westerly jets. The tropical Pacific and the North Atlantic are the main external forcing signals of the circulation pattern: SST characteristics showed&amp;#160;that the negative phase of the North Atlantic&amp;#160;SST&amp;#160;Tripole&amp;#160;in spring, from winter of the previous year to summer of the current year, SST of the equatorial Middle East Pacific developed&amp;#160;from warm to cold.&amp;#160;The distribution of 500 hPa height field corresponding to the main mode of summer precipitation in Northwest China is similar to that of EU remote correlation type. An index(I&lt;sub&gt;Hgt&lt;/sub&gt;)&amp;#160;was&amp;#160;defined to reflect circulation patterns in mid-latitude and subtropical regions, when the index is positive/negative, most of the precipitation in northwest China is more/less. After 2000, the correlation between the two increased significantly. Given the performance of the I&lt;sub&gt;Hgt&lt;/sub&gt;&amp;#160;index in describing the summer&amp;#160;precipitation, it could be used as a good indicator in the monitoring and prediction of the summer&amp;#160;precipitation in Northwest&amp;#160;China.&lt;/p&gt;

scholarly journals Assessing the Sensitivity of Riparian Algarrobo Dulce (Prosopis flexuosa DC) Radial Growth to Hydrological Changes

2016 ◽  
Vol 43 (1) ◽  
pp. 1-8 ◽  
Author(s):  
Sergio Piraino ◽  
Fidel Alejandro Roig
Keyword(s):  
Radial Growth ◽  
Environmental Changes ◽  
Precipitation Amount ◽  
Summer Precipitation ◽  
Late Summer ◽  
Monte Desert ◽  
Hydrological Changes ◽  
Tightly Coupled ◽  
Prosopis Flexuosa ◽  
Ecological Importance

Abstract Ecotones, as for example riparian zones, have long interested ecologists, due to their potential role in generating species biodiversity and evolutionary novelty, as well as their sensitivity to environmental changes. Along riparian areas, vegetation is recognized for its ecological importance in several ecosystemic processes. In the Central Monte Desert (central-west Argentina), Prosopis flexuosa grows in territories characterized by a permanent access to water reservoirs, e.g. along riverbanks, where the species forms the classic gallery forests. Despite the ecosystemic role of the different Prosopis species distributed in arid lands, thus far no analysis has been conducted regarding the relation between their radial growth and hydrological changes, namely streamflow variability, in riparian settings. To fill this gap of knowledge, we performed a dendrochronological analysis considering several riparian P. flexuosa trees differing in their spatial position in relation to the riverbank. Pointer years, correlation function, and regression analyses show differences in the dendrohydrological signal of the studied species, probably function of tree distance from the river. In this sense, radial growth of trees distributed near the riverbank is tightly coupled to spring-summer (September to March) stream-flow variability, whereas for farthest trees the ring development is driven by a combination of winter and spring river discharge and late-summer precipitation amount. The presented results demonstrate the potentiality of P. flexuosa, and in a broader sense of the Prosopis genus, in dendrohydrological studies.

scholarly journals Impact of elevated precipitation, nitrogen deposition and warming on soil respiration in a temperate desert

2017 ◽  
Author(s):  
Ping Yue ◽  
Xiaoqing Cui ◽  
Yanming Gong ◽  
Kaihui Li ◽  
Keith Goulding ◽  
...  
Keyword(s):  
Soil Respiration ◽  
Soil Temperature ◽  
Carbon Dioxide Emissions ◽  
Structural Equation ◽  
Environmental Changes ◽  
Northwest China ◽  
N Deposition ◽  
Single Factor ◽  
Desert Ecosystems ◽  
Temperate Desert

Abstract. Soil respiration (Rs) is the most important source of carbon dioxide emissions from soil to atmosphere. However, it is unclear what the interactive response of Rs would be to environmental changes such as elevated precipitation, nitrogen (N) deposition and warming, especially in unique temperate desert ecosystems. To investigate this an in situ field experiment was conducted in the Gurbantunggut Desert, northwest China, from September 2014 to October 2016. The results showed that precipitation and N deposition significantly increased Rs, but warming decreased Rs, which was mainly through its impact on the variation of soil moisture at 5 cm depth. In addition, the interactive response of Rs to combinations of the factors was much less than that of any single-factor, and the main interaction being a positive effect, except interaction from increased precipitation and high N deposition (60 kg N ha−1 yr−1). Although Rs was found to be a unimodal change pattern with the variation of soil mositure, soil temperature and soil NH4+-N content, and it was signicantly postively correlated to soil dissloved organic carbon (DOC) and pH, but from a structural equation model found that soil temperature was the most important controlling factor. Those results indicated that Rs was mainly interactively controlled by the soil multi-environmental factors and soil nutrients, and was very sensitive to elevated precipitation, N deposition and warming. But the interactions of multiple factors largely reduced between-year variation of Rs more than any single-factor, suggesting that the carbon cycle in temperate deserts could be profoundly influenced by positive carbon-climate feedbacks.

scholarly journals Impact of regional climatic conditions on tree growth on mainland Greece

2019 ◽  
Vol 46 (2) ◽  
pp. 127-136 ◽  
Author(s):  
Panagiotis P. Koulelis ◽  
Evangelia N. Daskalakou ◽  
Kostas E. Ioannidis
Keyword(s):  
Tree Growth ◽  
Environmental Changes ◽  
Basal Area ◽  
Summer Precipitation ◽  
Climatic Conditions ◽  
Forest Growth ◽  
Management Scenarios ◽  
Climatic Fluctuations ◽  
Tree Vitality ◽  
Intensive Monitoring

AbstractForest growth is commonly used to explore tree vitality and ability to resist to environmental changes or climatic fluctuations. This paper illustrates and examines how regional climatic conditions can be related to the decline of tree growth, which were found to be more distinct in Quercus frainetto Ten. (Hungarian oak) and Fagus sylvatica L. (European beech) and less pronounced in Abies borissi-regis Matt f. (Bulgarian fir) on three long-term intensive monitoring plots (ICP Forests-Level II) in Greece during the period 1996–2009. Relative basal area increment and volume increment were calculated, expressing tree growth in terms of mean relative annual periodic increment. A decline in the growth of basal area and volume was observed after hot and dry periods, where annual temperatures and precipitation were far from the mean of the analyzed period. This observation was statistically confirmed in oak and beech plots regarding summer precipitation only and are in agreement with the findings of previous studies in Europe. The representativeness of the results at a national scale needs further investigation, although our results provide a good basis for further and more intensive monitoring programs to address various forest management scenarios against the background of potential climatic changes in the Mediterranean area.

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