Ecohydrology

2019 ◽  
Author(s):  
Valeriy Ivanov ◽  
Simone Fatichi ◽  
Edoardo Daly
Keyword(s):  
Water Resource Management ◽  
Water Cycle ◽  
Water Flux ◽  
Terrestrial Ecosystems ◽  
Limiting Factor ◽  
Atmospheric Sciences ◽  
Abiotic Environment ◽  
Vegetation Control ◽  
Climatic Regions ◽  
Interdisciplinary Field

Ecohydrology is a cross-disciplinary field that emerged in the early 2000s as a result of recognition of the need to better understand complex, multifaceted interactions occurring in terrestrial ecosystems and their connection to the water cycle. In this article, ecohydrology is viewed as the science that studies how water in all its forms links living organisms and their abiotic environment to define their function, interactions, structure, and distribution. As a highly interdisciplinary field, ecohydrology draws from hydrology, ecology, atmospheric sciences, plant ecophysiology, biophysics, hydrodynamics, soil science, geomorphology, biogeochemistry, agronomy, and even landscape architecture. Basic science questions and land and water resource management issues are addressed in the field. A range of temporal scales, from minutes (such as in stomatal response to a changing environment) to millennia (such as that characteristic of landscape evolution period), is relevant to studies in ecohydrology. Likewise, spatial extent of analysis covers a spectrum ranging from ~10–6 m (e.g., concerned with leaf stomatal cavities or soil pores), to regional scales at ~106 m. As other sciences, ecohydrologic research relies on theoretical analysis, observation-based inference and experimentation, and computational approaches. The latter are becoming powerful, permitting experimentation and tests of mathematical descriptions of relevant processes and mechanisms. As evidenced by the publication record, one the main scopes of ecohydrology has been to understand how water available to ecosystems is used by vegetation and impacts the water cycle through the process of evapotranspiration. This review draws from this literature thus having a prevailing emphasis on vegetation control of water fluxes (i.e., transpiration) and the bilateral interactions between vegetation and abiotic environment. This perspective is justified by the key role of transpiration in the water cycle: it is the largest water flux from vegetated land to the atmosphere. The field of ecohydrology has analyzed different climatic regions and areas. Arid and semiarid ecosystems, where water is the major limiting factor of ecosystem functioning, are viewed as one of the key foci in ecohydrologic studies, largely driving the establishment of the field. The role that transpiration has on rainfall via water recirculation and the potential effects of deforestation are the emphasis of tropical ecohydrology. The large changes in the hydrologic budget associated with urbanization are addressed in urban ecohydrologic studies. One may expect that future focus will be on understanding of the transformation of terrestrial ecosystems, as we know them, due to ongoing and anticipated changes in the hydrologic cycle.

scholarly journals Functional convergence of biosphere–atmosphere interactions in response to meteorology

2020 ◽  
Author(s):  
Christopher Krich ◽  
Mirco Migliavacca ◽  
Diego G. Miralles ◽  
Guido Kraemer ◽  
Tarek S. El-Madany ◽  
...  
Keyword(s):  
Land Surface ◽  
Water Cycle ◽  
Causal Structure ◽  
Terrestrial Ecosystems ◽  
Mediterranean Ecosystems ◽  
Meteorological Conditions ◽  
Surface Fluxes ◽  
Vegetation Types ◽  
Climatic Regions ◽  
Novel Algorithms

Abstract. Understanding the dependencies of the terrestrial carbon and water cycle is a prerequisite to anticipate their behaviour under climate change conditions. However, terrestrial ecosystems and the atmosphere interact via a multitude of variables, time- and space scales. Additionally the interactions might differ among vegetation types or climatic regions. Today, novel algorithms aim to disentangle the causal structure behind such interaction from empirical data. Visualising the estimated structure in networks, the nodes represent relevant meteorological determinants and land-surface fluxes, and the links dependencies among them possibly including their lag and strength. Here we show that biosphere–atmosphere interactions are strongly shaped by meteorological conditions. For example, we find that temperate and high latitude ecosystems during peak productivity exhibit very similar biosphere–atmosphere interaction networks as tropical forests. In times of anomalous conditions like drought though, both ecosystems behave more like Mediterranean ecosystems during their dry season. Our results demonstrate that ecosystems from different climate or vegetation types have similar biosphere–atmosphere interactions if their meteorological conditions are similar. We anticipate our analysis to foster the use of network approaches as they allow a more comprehensive understanding of the state of ecosystem functioning. Long term or even irreversible changes in network structure are rare and thus can be indicators of fundamental functional ecosystem shifts.

scholarly journals Seasonal partitioning of precipitation between streamflow and evapotranspiration, inferred from end-member splitting analysis

2020 ◽  
Author(s):  
James Kirchner ◽  
Scott Allen
Keyword(s):  
Rainy Season ◽  
Water Cycle ◽  
Water Flux ◽  
Water Storage ◽  
Terrestrial Ecosystems ◽  
Green Water ◽  
Blue Water ◽  
Stream Channels ◽  
Catchment Scale ◽  
Isotopic Tracers

<p>The terrestrial water cycle partitions precipitation between its two ultimate fates: "green water" that is evaporated or transpired back to the atmosphere, and "blue water" that is discharged to stream channels.  Measuring this partitioning is difficult, particularly on seasonal timescales.  End-member mixing analysis has been widely used to quantify streamflow as a mixture of isotopically distinct sources, but knowing where streamwater comes from is not the same as knowing where precipitation goes, and this latter question is the one we seek to answer.  Here we introduce "end-member splitting analysis", which uses isotopic tracers and water flux measurements to quantify how isotopically distinct inputs (such as summer vs. winter precipitation) are partitioned into different ultimate outputs (such as evapotranspiration and summer vs. winter streamflow).  End-member splitting analysis has modest data requirements and can potentially be applied in many different catchment settings.  We illustrate this data-driven, model-independent approach with publicly available biweekly isotope time series from Hubbard Brook Watershed 3.  A marked seasonal shift in isotopic composition allows us to distinguish rainy-season (April-November) and snowy-season (December-March) precipitation, and to trace their respective fates.  End-member splitting shows that about one-sixth (18±2%) of rainy-season precipitation is discharged during the snowy season, but this accounts for over half (60±9%) of snowy-season streamflow.  By contrast, most (55±13%) snowy-season precipitation becomes streamflow during the rainy season, where it accounts for 38±9% of rainy-season streamflow.  Our analysis thus shows that significant fractions of each season's streamflow originated as the other season's precipitation, implying significant inter-seasonal water storage within the catchment, as both groundwater and snowpack.  End-member splitting can also quantify how much of each season's precipitation is eventually evapotranspired.  At Watershed 3, we find that only about half (44±8%) of rainy-season precipitation evapotranspires, but almost all (85±15%) evapotranspiration originates as rainy-season precipitation, implying that there is relatively little inter-seasonal water storage supplying evapotranspiration.  This proof-of-concept study demonstrates that end-member mixing and splitting yield different, but complementary, insights into catchment-scale partitioning of precipitation into blue water and green water.  It could thus help in gauging the vulnerability of both water resources and terrestrial ecosystems to changes in seasonal precipitation.</p>

scholarly journals The effect of deforestation on the water cycle in the amazon basin: an attempt reformulate the problem

1985 ◽  
Vol 15 (3-4) ◽  
pp. 307-310 ◽  
Author(s):  
J. R. Gat ◽  
Ε. Matsui ◽  
Ε. Salati
Keyword(s):  
Large Scale ◽  
Amazon Basin ◽  
Water Cycle ◽  
Water Flux ◽  
Atmospheric Stability ◽  
Local Heat ◽  
Physical Geography ◽  
Cloud Formation ◽  
Evaporative Water ◽  
Stability Structure

If widespread deforestation in Amazon results in reduced evaporative water flux, then either a decrease in evaporation is compensated locally by reduced rainfall,or else changed moisture balance expresses itself downwind in the yet undisturbed forest. The question of where rain will occur is crucial. It is suggested that the appearance of clouds and the occurrence of rainout is governed primarily by the interplay of local meteorologic and physical geography parameters with the atmospheric stability structure except for a few well-defined periods when rain is dominated by large scale atmospheric instability. This means that the study of these phenomena (local heat balances,studies on cloud formation mechanism, vertical atmospheric stability, etc.) must be made on the scale of the cloud size, a few tens of kilometers at most.

scholarly journals Complementary Relationship and Dual Crop Coefficient Approach-Based Study on Green Water Separation

Water ◽  
2019 ◽  
Vol 11 (2) ◽  
pp. 378
Author(s):  
Na Fu ◽  
Xiaoyu Song ◽  
Lu Xia ◽  
Lanjun Li ◽  
Huaiyou Li ◽  
...  
Keyword(s):  
Water Resource Management ◽  
Statistical Tests ◽  
Water Flux ◽  
Crop Coefficient ◽  
Green Water ◽  
Pinus Tabulaeformis ◽  
Planted Forests ◽  
Ecological Processes ◽  
Water Separation ◽  
Complementary Relationship

Separating productive green water from non-productive green water could determine the potential for improving green water use through water-to-vapor conversion and the optimization of green water resource management. This study selected three typical planted forests of Robinia pseudoacacia, Platycladus orientalis, and Pinus tabulaeformis in the Nanxiaohegou sub-basin, a typical small sub-basin located in the gully region of the Loess Plateau. A combination of field monitoring, hydrological models, and statistical tests was used to obtain the crop coefficient and to differentiate productive green water from non-productive green water, based on the hydrological, climatic, and ecological processes in the basin. The results demonstrated that the complementary relationship areal evapotranspiration (CRAE) model was the most effective complementary relationship-based model for the simulation. Based on the calibrated parameters, it could be used for the simulation of green water flux of different vegetation types in the studied region. In the Nanxiaohegou sub-basin, the amounts of productive green water, non-productive green water, and total green water flux of R. pseudoacacia were the highest among all three types of vegetation, followed by those of P. orientalis and P. tabulaeformis forests during the growing seasons between 2015 and 2017.

scholarly journals Satellite Remote Sensing of Precipitation and the Terrestrial Water Cycle in a Changing Climate

2019 ◽  
Vol 11 (19) ◽  
pp. 2301 ◽  
Author(s):  
Vincenzo Levizzani ◽  
Elsa Cattani
Keyword(s):  
Water Resource Management ◽  
Water Cycle ◽  
Climatic Conditions ◽  
Global Perspective ◽  
Water Vapor Transport ◽  
Current Status ◽  
Active Sensors ◽  
Climate Conditions ◽  
Terrestrial Water ◽  
Life On Earth

The water cycle is the most essential supporting physical mechanism ensuring the existence of life on Earth. Its components encompass the atmosphere, land, and oceans. The cycle is composed of evaporation, evapotranspiration, sublimation, water vapor transport, condensation, precipitation, runoff, infiltration and percolation, groundwater flow, and plant uptake. For a correct closure of the global water cycle, observations are needed of all these processes with a global perspective. In particular, precipitation requires continuous monitoring, as it is the most important component of the cycle, especially under changing climatic conditions. Passive and active sensors on board meteorological and environmental satellites now make reasonably complete data available that allow better measurements of precipitation to be made from space, in order to improve our understanding of the cycle’s acceleration/deceleration under current and projected climate conditions. The article aims to draw an up-to-date picture of the current status of observations of precipitation from space, with an outlook to the near future of the satellite constellation, modeling applications, and water resource management.

scholarly journals Using modelled discharge to develop satellite-based river gauging: a case study for the Amazon Basin

2018 ◽  
Vol 22 (12) ◽  
pp. 6435-6448 ◽  
Author(s):  
Jiawei Hou ◽  
Albert I. J. M. van Dijk ◽  
Luigi J. Renzullo ◽  
Robert A. Vertessy
Keyword(s):  
River Discharge ◽  
Water Resource Management ◽  
Large Scale ◽  
Amazon Basin ◽  
Water Cycle ◽  
Detection System ◽  
Grid Cell ◽  
Cost Effective ◽  
Satellite Observation ◽  
Moderate Resolution Imaging Spectroradiometer

Abstract. River discharge measurements have proven invaluable to monitor the global water cycle, assess flood risk, and guide water resource management. However, there is a delay, and ongoing decline, in the availability of gauging data and stations are highly unevenly distributed globally. While not a substitute for river discharge measurement, remote sensing is a cost-effective technology to acquire information on river dynamics in situations where ground-based measurements are unavailable. The general approach has been to relate satellite observation to discharge measured in situ, which prevents its use for ungauged rivers. Alternatively, hydrological models are now available that can be used to estimate river discharge globally. While subject to greater errors and biases than measurements, model estimates of river discharge do expand the options for applying satellite-based discharge monitoring in ungauged rivers. Our aim was to test whether satellite gauging reaches (SGRs), similar to virtual stations in satellite altimetry, can be constructed based on Moderate Resolution Imaging Spectroradiometer (MODIS) optical or Global Flood Detection System (GFDS) passive microwave-derived surface water extent fraction and simulated discharge from the World-Wide Water (W3) model version 2. We designed and tested two methods to develop SGRs across the Amazon Basin and found that the optimal grid cell selection method performed best for relating MODIS and GFDS water extent to simulated discharge. The number of potential river reaches to develop SGRs increases from upstream to downstream reaches as rivers widen. MODIS SGRs are feasible for more river reaches than GFDS SGRs due to its higher spatial resolution. However, where they could be constructed, GFDS SGRs predicted discharge more accurately as observations were less affected by cloud and vegetation. We conclude that SGRs are suitable for automated large-scale application and offer a possibility to predict river discharge variations from satellite observations alone, for both gauged and ungauged rivers.

Grazing alters environmental control mechanisms of evapotranspiration in an alpine meadow of the Tibetan Plateau

2019 ◽  
Vol 12 (5) ◽  
pp. 834-845
Author(s):  
Tingting An ◽  
Mingjie Xu ◽  
Tao Zhang ◽  
Chengqun Yu ◽  
Yingge Li ◽  
...  
Keyword(s):  
Community Structure ◽  
Tibetan Plateau ◽  
Alpine Meadow ◽  
Environmental Control ◽  
Water Cycle ◽  
Limiting Factor ◽  
Peak Time ◽  
The Tibetan Plateau ◽  
Control Mechanisms ◽  
Water Conditions

Abstract Aims Evapotranspiration (ET) is an important component of the terrestrial water cycle and is easily affected by external disturbances, such as climate change and grazing. Identifying ET responses to grazing is instructive for determining grazing activity and informative for understanding the water cycle. Methods This study utilized 2 years (2014 and 2017) of eddy covariance data to test how grazing regulated ET for an alpine meadow ecosystem on the Tibetan Plateau (TP) by path analysis. Important Findings Radiation dominated ET with a decision coefficient of 64–74%. The soil water content (SWC) worked as the limiting factor in the fenced site. However, in the grazing site, the limiting factor was the vapor pressure deficit (VPD). Grazing had large effects on ET because it greatly affected the water conditions. The SWC and VPD were enhanced by 14.63% and 4.36% in the grazing site, respectively. Therefore, sufficient water was supplied to ET, especially during drought, and strengthened the transpiration pull. As a result, a favorable micrometeorological environment was created for ET. Grazing shifted the limiting factor of ET from the SWC to VPD, which weakened the limiting effect of the water conditions on ET and advanced the ET peak time. In addition, grazing altered the compositions of ET by changing the community structure, which directly resulted in an increased ET. In summary, grazing enhanced ET through altering the community structure and micrometeorological environments. The findings of this study further improve our understanding of the driving mechanisms of grazing on ET and will improve our predictions for the global water cycle.

scholarly journals Altered trends in carbon uptake in China's terrestrial ecosystems under the enhanced summer monsoon and warming hiatus

2019 ◽  
Vol 6 (3) ◽  
pp. 505-514 ◽  
Author(s):  
Honglin He ◽  
Shaoqiang Wang ◽  
Li Zhang ◽  
Junbang Wang ◽  
Xiaoli Ren ◽  
...  
Keyword(s):  
Summer Monsoon ◽  
Climate Changes ◽  
Terrestrial Ecosystems ◽  
Co2 Concentration ◽  
Carbon Uptake ◽  
Climate Effect ◽  
Climatic Regions ◽  
Ecosystem Carbon ◽  
Decadal Scale ◽  
Warming Hiatus

AbstractThe carbon budgets in terrestrial ecosystems in China are strongly coupled with climate changes. Over the past decade, China has experienced dramatic climate changes characterized by enhanced summer monsoon and decelerated warming. However, the changes in the trends of terrestrial net ecosystem production (NEP) in China under climate changes are not well documented. Here, we used three ecosystem models to simulate the spatiotemporal variations in China's NEP during 1982–2010 and quantify the contribution of the strengthened summer monsoon and warming hiatus to the NEP variations in four distinct climatic regions of the country. Our results revealed a decadal-scale shift in NEP from a downtrend of –5.95 Tg C/yr2 (reduced sink) during 1982–2000 to an uptrend of 14.22 Tg C/yr2 (enhanced sink) during 2000–10. This shift was essentially induced by the strengthened summer monsoon, which stimulated carbon uptake, and the warming hiatus, which lessened the decrease in the NEP trend. Compared to the contribution of 56.3% by the climate effect, atmospheric CO2 concentration and nitrogen deposition had relatively small contributions (8.6 and 11.3%, respectively) to the shift. In conclusion, within the context of the global-warming hiatus, the strengthening of the summer monsoon is a critical climate factor that enhances carbon uptake in China due to the asymmetric response of photosynthesis and respiration. Our study not only revealed the shift in ecosystem carbon sequestration in China in recent decades, but also provides some insight for understanding ecosystem carbon dynamics in other monsoonal areas.

GRACE/GRACE-FO to constrain regional to global Evapotranspiration

2020 ◽  
Author(s):  
John Reager ◽  
Madeleine Pascolini-Campbell
Keyword(s):  
Large Scale ◽  
Water Cycle ◽  
Water Flux ◽  
Mass Conservation ◽  
Mass Change ◽  
Global Water Cycle ◽  
Basin Scale ◽  
Global Land ◽  
Terrestrial Water ◽  
Global Water

<p>A frontier in hydrology lies in understanding the potential impacts of a warming planet on water cycle variability from regional to global scales.  The fluxes that constitute the terrestrial water cycle present various complexity in observability, with Evapotranspiration (ET) being generally the most challenging variable to quantify directly.  Because of the ability to apply mass conservation and to "close" a water flux budget across scales, mass change measurements present the best opportunity to quantify evapotranspiration and changes in evapotranspiration at larger scales, ranging from basins to global. Here we present work on: (1) using GRACE/GFO observations to estimate basin-scale ET in the continental United States as a target for validation and error analysis of up-scaled ET products from other sources, and (2) using GRACE/GFO observations to estimate ET globally over the full joint record (2003-2020) in order to quantify observed changes in the global water cycle.  We find that because of the way that errors in mass change measurements inherently change in scale (i.e. decreasing with larger study domains), GRACE/GFO measurements offer a very clear and robust uncertainty quantification approach for large scale ET monitoring.  We also find that there is a clear and statistically significant signal in global land ET over the record length that indicates changes in the global water cycle consistent with our understanding of climate change.  These methods and results will be presented and discussed.</p>

scholarly journals Putting WASH in the water cycle: climate change, water resources and the future of water, sanitation and hygiene challenges in Pacific Island Countries

2015 ◽  
Vol 5 (2) ◽  
pp. 183-191 ◽  
Author(s):  
Wade L. Hadwen ◽  
Bronwyn Powell ◽  
Morgan C. MacDonald ◽  
Mark Elliott ◽  
Terence Chan ◽  
...  
Keyword(s):  
Climate Change ◽  
Sea Level Rise ◽  
Sea Level ◽  
Water Resource Management ◽  
Water Cycle ◽  
Pacific Island ◽  
Water And Sanitation ◽  
Sanitation And Hygiene ◽  
The Pacific ◽  
Pacific Island Countries

The Pacific region presents some of the lowest water and sanitation coverage figures globally, with some countries showing stagnating or even declining access to improved water and sanitation. In addition, Pacific Island Countries (PICs) are among the most vulnerable countries on the globe to extreme and variable climatic events and sea-level rise caused by climate change. By exploring the state of water and sanitation coverage in PICs and projected climatic variations, we add to the growing case for conserving water, sanitation and hygiene (WASH) interventions within a holistic integrated water resource management (IWRM) framework. PICs face unique challenges of increasing variability in rainfall (leading to drought and flooding), increasing temperatures, and likely higher than average sea-level rise, all of which impact on freshwater security. Add to this geographic and economic isolation, and limited human and physical resources, and the challenge of WASH provision increases dramatically. In this setting, there is a stronger case than ever for adopting a holistic systems understanding, as promoted by IWRM frameworks, to WASH interventions so that they consider past and current challenges as well as future scenarios.

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