Fernando Jaramillo holds a Ph.D. in Physical Geography from Stockholm University with a focus on hydrology and freshwater resources. He studies the historical effects of both climate change and land and water use on freshwater availability and changes, from local to global scales. His main areas of research are hydroclimatic change via de Budyko framework, human water consumption, and application of space technologies to understand changes and impacts on water resources.
-Head(Co) of the Water, Permafrost and Environmental Systems Unit
-Leader of Water, Biogeochemistry and Climate/ Bolin Centre for Climate Research
Postdoc Francisco Peña
Teaching activities (selected)
Responsible for GE8032-Advanced Hydrology-SU
Responsible for GE8031-Land and Water Risk Assessment-SU
Lecturer GE7025-Global Water Vulnerability and Resilience-SU
Lecturer GE7069-Traffic and Environment-SU
Lecturer BL7018-Management of Aquatic Res. in the Tropics-SU
Lecturer MJ2659-Technology and Ecosystems-KTH
My research aims to 1) determine how human activities such as agriculture, forestry, and water regulation by dams affect water resources on the Earth's surface. It also aims to quantify changes in surface water resources. Before my position as Assistant professor in Hydrologic Transport, I studied the effects of agriculture on water fluxes such as runoff and evapotranspiration. Nowadays, I have realised the importance of water storage as a keystone of water transport, focusing on wetlands, lakes and impounded reservoirs. With recent works lead in the African continent, Colombia, China, the United States, Sweden, and the global scale, I have confirmed that humans are reshaping the world’s water resources. These effects are direct, such as land and water use, or indirect as anthropogenic climate change. However, identifying the corresponding responses of water resources is not straightforward, as hydrological processes are primarily understood at the local scale due to the influence of specific local conditions. I now explore new technologies and methods using space missions and observations to understand hydrological changes.
The research question has been consistently the following: Is the impact of humans on the availability of water cycle larger than climate, and is our use of water resources sustainable? During my tenure-track position, I have aimed to answer this question by studying the hydrologic and climatic impacts of impounded reservoirs, the sustainability of agriculture in developing countries, and how changes in water resources can be detected from space. The disciplines used as a canvas to answer this question include hydrology, hydroclimatology, geodesy, remote sensing and sustainability science.
I have now constructed an independent line of research based on hydroclimatology, hydrogeodesy, sustainability studies of water resources and remote sensing across three main lines of research: 1) Water consumption and impacts of impounded reservoirs, 2) Sustainable water use from local to global scales, and 3) Detection of hydrological changes from space.
For example, regarding the first line of research, we found that tree growth around an impounded reservoir in China could only be explained by a simultaneous effect of favourable regional climate conditions possible by the reservoir’s impoundment. Regarding the second research line on water sustainability, we have quantified the human water footprint and determined a water-related planetary limit defining the safe operating space for humanity. Along with my first PhD student, I have also shown how sustainable water management can substantially increase crop production in developing countries and how poverty, overpopulation, risk aversion, remoteness, and post-conflict patriarchal systems represent barriers to the adoption of these practices. Last but not least, with my specific passion for wetlands, shown by my extended scientific production on these types of water resources, I show that water management in wetlands is necessary to achieve sustainable development.
Finally, regarding the third line of research, I am a hydrologist who has slowly expanded his expertise to space technologies and radar satellite sensors. Interferometric Synthetic Aperture Radar (InSAR) is a radar technology used to track changes in space and time of water-surface levels. I have used this technology, commonly used to study the movements of the ground, to identify hydrological dynamics and processes in inland waters. I have also developed a method based on InSAR to track changes in small lakes and wetlands, tested in lakes in Sweden and Ecuador. I consider this last outcome a breakthrough as it represents a possibility to monitor water level changes in many small and ungauged wetlands and lakes worldwide.
A selection from Stockholm University publication database
A planetary boundary for green water
2022. Lan Wang-Erlandsson (et al.). Nature Reviews Earth & Environment 3 (6), 380-392Article
Green water — terrestrial precipitation, evaporation and soil moisture — is fundamental to Earth system dynamics and is now extensively perturbed by human pressures at continental to planetary scales. However, green water lacks explicit consideration in the existing planetary boundaries framework that demarcates a global safe operating space for humanity. In this Perspective, we propose a green water planetary boundary and estimate its current status. The green water planetary boundary can be represented by the percentage of ice-free land area on which root-zone soil moisture deviates from Holocene variability for any month of the year. Provisional estimates of departures from Holocene-like conditions, alongside evidence of widespread deterioration in Earth system functioning, indicate that the green water planetary boundary is already transgressed. Moving forward, research needs to address and account for the role of root-zone soil moisture for Earth system resilience in view of ecohydrological, hydroclimatic and sociohydrological interactions.
Causes and consequences of recent degradation of the Magdalena River basin, Colombia
2022. Jorge Salgado (et al.). Limnology and Oceanography LettersArticle
The Magdalena River in Colombia is one of the world's largest (discharge = 7100 m3 s−1) tropical rivers, hosting > 170 aquatic vertebrate species. However, concise synthesis of the current ecological and environmental status is lacking. By documenting the anthropogenic stressors impacting the river on time scales ranging from centuries to decades, we found that the river system is subject to the compounding impacts of climate change, river impoundment, invasive alien species (IAS), catchment deforestation, and water pollution. We show that the Magdalena is a woefully understudied ecosystem relative to its critical importance to Colombia's economy, culture, and biodiversity compared with other similarly sized tropical rivers. We emphasize the need for research on (1) IAS population and ecological dynamics, (2) river damming and its links with IAS and climate change, and (3) land-use changes as well as identifying sources of water pollution and strategies for mitigation.
Investing in sustainable intensification for smallholders: quantifying large-scale costs and benefits in Uganda
2022. Luigi Piemontese (et al.). Environmental Research Letters 17 (4)Article
In Uganda, upgrading smallholder agriculture is a necessary step to achieve the interlinked sustainable development goals of hunger eradication, poverty reduction and land degradation neutrality. However, targeting the right restoration practices and estimate their cost-benefit at the national scale is difficult given the highly contextual nature of restoration practices and the diversity of small-scale interventions to be adopted. By analysing the context-specific outcomes of 82 successful case studies on different sustainable land and water management (SLWM) in Uganda, we estimated that out-scaling of existing successful practices to 75% of agricultural land would require a one-time investment of US$ 4.4 billion from smallholders. Our results show that, besides the many social and environmental benefit commonly associated to SLWM, a wide outscale of SLWM could generate US$ 4.7 billion every year, once the practices are fully operational. Our context-specific estimates highlight the profitability of investing in smallholder farming to achieve the sustainable development goals in Uganda, with geographical differences coming from specific social-ecological conditions. This study can guide sustainable intensification development by targeting the most suitable SLWM practices and plan for adequate financial support from government, investors and international development aids to smallholder farming.
Nordic hydrological frontier in the 21st century
2022. H. Marttila (et al.). Hydrology Research 53 (5), 700-715Article
The 21st century has brought new challenges and opportunities and has also increased demands on the Nordic hydrological community. Our hydrological science focus and approaches need rethinking and adaptation to the changing requirements of society in response to climate change and human interventions, in search of more comprehensive and cross-disciplinary solutions. This commentary highlights new possibilities and suggests vital steps forward for the scientific discipline within Nordic hydrological research. By providing a common direction, we hope to increase awareness, accelerate progress in the hydrological community, and emphasize the importance of hydrological knowledge for serving other fields of science and society at large. We hope that our vision and the opportunities we identify will raise awareness of the scientific discipline and assist in the long-term development of the Nordic hydrological frontier in the 21st century.
Retrieval of Simultaneous Water-Level Changes in Small Lakes With InSAR
2022. S. Palomino-Ángel (et al.). Geophysical Research Letters 49 (2)Article
Monitoring water level changes is necessary to manage, conserve and restore natural, and anthropogenic lake systems. However, the in-situ monitoring of lake systems is unfeasible due to limitations of costs and access. Furthermore, current remote sensing methods are restricted to large lakes and low spatial resolutions. We develop a novel approach using subsequential pixel-wise observations of the Sentinel-1B sensor based on interferometric synthetic aperture radar to detect water level changes in small lakes. We used 24 small ungauged lakes of the Cajas Massif lake system in Ecuador for development and validation. We found Differential Interferometric Synthetic Aperture Radar (DInSAR)-derived water level changes across lakes to be consistent with precipitation, capturing the peak of the wet seasons. Furthermore, accumulated water level changes could be explained by differences in lake area among lakes. Although with limitations, this study shows the underutilized potential of DInSAR to understand water level changes in small lakes with current radar data availability.
Scaling relations reveal global and regional differences in morphometry of reservoirs and natural lakes
2022. Ylva Sjöberg (et al.). Science of the Total Environment 822Article
Water bodies provide essential ecosystem services linked to morphometric features that might differ between natural lakes and reservoirs. We use the HydroLAKES global dataset to quantitatively compare large (area > 1 km2) reservoirs and natural lakes in terms of scaling exponents between morphometric measures (volume, area, shore length). These exponents are further compared to those expected from geometrical assumptions and constraints. Lakes cover a larger range of volumes for the same range of surface areas than reservoirs, and have a larger volume-area scaling exponent. The volume-area scaling exponent for reservoirs (but not natural lakes) and the area-shore length exponent for all water bodies follow the predictions for self-affine surfaces. Land cover and terrain influence the scaling relations more for lakes than for reservoirs. These morphometric differences may be used to model the impact of reservoirs and lakes on hydrological processes and associated ecosystem services at regional to global scales.
An Earth system law perspective on governing social-hydrological systems in the Anthropocene
2021. Hanna Ahlström (et al.). Earth System Governance 10Article
The global hydrological cycle is characterized by complex interdependencies and self-regulating feedbacks that keep water in an ever-evolving state of flux at local, regional, and global levels. Increasingly, the scale of human impacts in the Anthropocene is altering the dynamics of this cycle, which presents additional challenges for water governance. Earth system law provides an important approach for addressing gaps in governance that arise from the mismatch between the global hydrological cycle and dispersed regulatory architecture across institutions and geographic regions. In this article, we articulate the potential for Earth system law to account for core hydrological problems that complicate water governance, including delay, redistribution, intertwinements, permanence, and scale. Through merging concepts from Earth system law with existing policy and legal principles, we frame an approach for addressing hydrological problems in the Anthropocene and strengthening institutional fit between established governance systems and the global hydrological cycle. We discuss how such an approach can be applied, and the challenges and implications for governing water as a cycle and complex social-hydrological system, both in research and practice.
Barriers to scaling sustainable land and water management in Uganda: a cross-scale archetype approach
2021. Luigi Piemontese (et al.). Ecology & Society 26 (3)Article
In African small-scale agriculture, sustainable land and water management (SLWM) is key to improving food production while coping with climate change. However, the rate of SLWM adoption remains low, suggesting a gap between generalized SLWM advantages for rural development across the literature, and the existence of context-dependent barriers to its effective implementation. Uganda is an example of this paradox: the SLWM adoption rate is low despite favorable ecological conditions for agriculture development and a large rural population. A systemic understanding of the barriers hindering the adoption of SLWM is therefore crucial to developing coherent policy interventions and enabling effective funding strategies. Here, we propose a cross-scale archetype approach to identify and link barriers to SLWM adoption in Uganda. We performed 80 interviews across the country to build cognitive archetypes, harvesting stakeholders’ perceptions of different types of barriers. We complemented this bottom-up perspective with a spatial archetype analysis to contextualize these results across different social-ecological regions. We found poverty trap, overpopulation, risk aversion, remoteness, and post-conflict patriarchal systems as cognitive archetypes that synthesize the different dynamics of barriers to SLWM adoption in Uganda. Our results reveal both specific and cross-cutting barriers. Ineffective extension services emerges as a ubiquitous barrier, whereas gender inequality is a priority barrier for large supported farms and farms in drier lowlands in northern Uganda. The combination of cognitive and spatial archetypes proposed here can help to overcome ineffective “one-size-fits-all” solutions and support context-specific policy plans to scale up SLWM, rationing resources to support sustainable intensification of agriculture.
Drivers and extent of surface water occurrence in the Selenga River Delta, Russia
2021. Saeid Aminjafari (et al.). Journal of Hydrology 38Article
Study region: Selenga River Delta (SRD), Russia.
Study focus: How is water occurrence changing in the SRD, and what are the hydroclimatic drivers behind these changes? The presence of water on the surface in river deltas is governed by land use, geomorphology, and the flux of water to and from the Delta. We trained an accurate image classification of the Landsat satellite imagery during the last 33 years to quantify surface water occurrence and its changes in the SRD. After comparing our estimations with global-scale data sets, we determined the hydrological drivers of these changes.
New hydrological insights for the region: We find mild decreases in water occurrence in 51% of the SRD's surface area from 1987-2002 to 2003-2020. Water occurrence in the most affected areas decreased by 20% and in the most water-gaining areas increased by 10%. We find a significant relationship between water occurrence and runoff (R-2 = 0.56) that does not exist between water occurrence and suspended sediment concentration (SSC), Lake Baikal's water level, and potential evapotranspiration. The time series of water occurrence follows the peaks in the runoff but not its long-term trend. However, the extremes in SSC do not influence surface water occurrence (R-2 < 0.1), although their long-term trends are similar. Contrary to expected, we find that the Delta has a relatively stable long-term water availability for the time being.
Exploring the influence of reservoir impoundment on surrounding tree growth
2021. Lian Sun (et al.). Advances in Water Resources 153Article
At the local scale, artificial impounded reservoirs in dry regions exert influence on the surrounding local climate. Impounded reservoirs have been found to alter precipitation patterns and increase temperature, specific humidity and surface evaporation. The consequences of impoundment or its related climatic changes on the surrounding vegetation are still not well understood. We here examined the potential effect on surrounding tree growth of the impoundment of the Ertan Reservoir, China, in 1998. We measured Yunnan pine tree rings at three sites on a slope close to the reservoir and two control sites far away from the reservoir. We compared the annual radial growth of tree rings at all sites with air temperature, precipitation and air humidity in the region. We also used cumulative distribution functions to quantify the probability of attributing radial growth changes to background climate variability. We find an enhancement of tree growth from 2000 to 2002, right after the reservoir's impounding in experimental and control sites. Hence, the tree growth can initially be explained by favourable conditions benefiting tree growth. However, we cannot entirely attribute such enhancement to the background climate variability when studying the relationship between tree growth and climatic variables over the 36 years and their probability of occurrence. Tree growth in the three years following impoundment can only be attributed to the simultaneous effect of favourable regional climate conditions and the reservoir's impoundment in itself. These conditions decrease vegetation stress by decreasing air temperature and increasing air relative humidity. Although the findings of this study shed more light on the environmental and climatic changes induced by the impoundment of reservoirs, they also call for the need of monitoring climatic variables in the vicinity of reservoirs.
Hydro-climatic changes of wetlandscapes across the world
2021. Imenne Åhlen (et al.). Scientific Reports 11 (1)Article
Assessments of ecosystem service and function losses of wetlandscapes (i.e., wetlands and their hydrological catchments) suffer from knowledge gaps regarding impacts of ongoing hydro-climatic change. This study investigates hydro-climatic changes during 1976–2015 in 25 wetlandscapes distributed across the world’s tropical, arid, temperate and cold climate zones. Results show that the wetlandscapes were subject to precipitation (P) and temperature (T) changes consistent with mean changes over the world’s land area. However, arid and cold wetlandscapes experienced higher T increases than their respective climate zone. Also, average P decreased in arid and cold wetlandscapes, contrarily to P of arid and cold climate zones, suggesting that these wetlandscapes are located in regions of elevated climate pressures. For most wetlandscapes with available runoff (R) data, the decreases were larger in R than in P, which was attributed to aggravation of climate change impacts by enhanced evapotranspiration losses, e.g. caused by land-use changes.
Multi-Sensor InSAR Assessment of Ground Deformations around Lake Mead and Its Relation to Water Level Changes
2021. Mehdi Darvishi (et al.). Remote Sensing 13 (3)Article
Changes in subsurface water resources might alter the surrounding ground by generating subsidence or uplift, depending on geological and hydrogeological site characteristics. Improved understanding of the relationships between surface water storage and ground deformation is important for design and maintenance of hydraulic facilities and ground stability. Here, we construct one of the longest series of Interferometric Synthetic Aperture Radar (InSAR) to date, over twenty-five years, to study the relationships between water level changes and ground surface deformation in the surroundings of Lake Mead, United States, and at the site of the Hoover Dam. We use the Small Baseline Subset (SBAS) and Permanent scatterer interferometry (PSI) techniques over 177 SAR data, encompassing different SAR sensors including ERS1/2, Envisat, ALOS (PALSAR), and Sentinel-1(S1). We perform a cross-sensor examination of the relationship between water level changes and ground displacement. We found a negative relationship between water level change and ground deformation around the reservoir that was consistent across all sensors. The negative relationship was evident from the long-term changes in water level and deformation occurring from 1995 to 2014, and also from the intra-annual oscillations of the later period, 2014 to 2019, both around the reservoir and at the dam. These results suggest an elastic response of the ground surface to changes in water storage in the reservoir, both at the dam site and around the reservoir. Our study illustrates how InSAR-derived ground deformations can be consistent in time across sensors, showing the potential of detecting longer time-series of ground deformation.
Water footprint and consumption of hydropower from basin-constrained water mass balance
2021. Lian Sun (et al.). Advances in Water Resources 153Article
Water management by the impoundment of reservoirs has been found to influence evapotranspiration not only locally but also at the basin scale. Highly regulated hydrological basins generally show the effect of a net increase in evapotranspiration accompanying the successive impoundment of reservoirs. However, understanding and isolating the effect from a particular single impounded reservoir remains a challenge due to the lack of long-term observation data required and the existence of many other drivers present at the basin scale. Focusing on the hydrological basin having the largest hydropower potential in China, we isolated in time and space and quantified the effects of a single impounded reservoir on evapotranspiration and the evaporative ratio (i.e., the ratio of actual evapotranspiration to precipitation) before and after the construction of the Ertan Dam in 1998. We find that the dam has increased evapotranspiration in the smallest subbasin by 46±15 mm/yr and the evaporative ratio by 0.05±0.015, from the period before impoundment (1983-1997) to that after impoundment (2000-2012). This increase is found only within the smallest differential subbasin holding the impounded reservoir and cannot be explained by other changes in land use or vegetation. We use this result from our hydrological basin-constrained approach to calculate the water footprint of the hydroelectric project as 16.5 m3/GJ, which accounts for additional hydroclimatic effects of the impoundment of the reservoir beyond the water surface. Hence, this study finds that when runoff data is available, the water consumption and the water footprint of hydropower projects can be calculated by water mass balance at the scale of their hydrological basins.
Data for wetlandscapes and their changes around the world
2020. Navid Ghajarnia (et al.). Earth System Science Data 12 (2), 1083-1100Article
Geography and associated hydrological, hydroclimate and land-use conditions and their changes determine the states and dynamics of wetlands and their ecosystem services. The influences of these controls are not limited to just the local scale of each individual wetland but extend over larger landscape areas that integrate multiple wetlands and their total hydrological catchment - the wetlandscape. However, the data and knowledge of conditions and changes over entire wetlandscapes are still scarce, limiting the capacity to accurately understand and manage critical wetland ecosystems and their services under global change. We present a new Wetlandscape Change Information Database (WetCID), consisting of geographic, hydrological, hydroclimate and land-use information and data for 27 wetlandscapes around the world. This combines survey-based local information with geographic shapefiles and gridded datasets of large-scale hydroclimate and land-use conditions and their changes over whole wetlandscapes. Temporally, WetCID contains 30-year time series of data for mean monthly precipitation and temperature and annual land-use conditions. The survey-based site information includes local knowledge on the wetlands, hydrology, hydroclimate and land uses within each wetlandscape and on the availability and accessibility of associated local data. This novel database (available through PANGAEA https://doi.org/10.1594/PANGAEA.907398; Ghajarnia et al., 2019) can support site assessments; cross-regional comparisons; and scenario analyses of the roles and impacts of land use, hydroclimatic and wetland conditions, and changes in whole-wetlandscape functions and ecosystem services.
Estimating the global potential of water harvesting from successful case studies
2020. Luigi Piemontese (et al.). Global Environmental Change 63Article
Water harvesting has been widely applied in different social-ecological contexts, proving to be a valuable approach to sustainable intensification of agriculture. Global estimates of the potential of water harvesting are generally based on purely biophysical assessments and mostly neglect the socioeconomic dimension of agriculture. This neglect becomes a critical factor for the feasibility and effectiveness of policy and funding efforts to mainstream this practice. This study uses archetype analysis to systematically identify social-ecological regions worldwide based on >160 successful cases of local water harvesting implementation. We delineate six archetypal regions which capture the specific social-ecological conditions of the case studies. The archetypes cover 19% of current global croplands with hotspots in large portions of East Africa and Southeast Asia. We estimate that the adoption of water harvesting in these cropland areas can increase crop production up to 60–100% in Uganda, Burundi, Tanzania and India. The results of this study can complement conventional biophysical analysis on the potential of these practices and guide policy development at global and regional scales. The methodological approach can be also replicated at finer scales to guide the improvement of rainfed agricultural.
Future Climate Change Renders Unsuitable Conditions for Paramo Ecosystems in Colombia
2020. Matilda Cresso (et al.). Sustainability 12 (20)Article
Paramo ecosystems are tropical alpine grasslands, located above 3000 m.a.s.l. in the Andean mountain range. Their unique vegetation and soil characteristics, in combination with low temperature and abundant precipitation, create the most advantageous conditions for regulating and storing surface and groundwater. However, increasing temperatures and changing patterns of precipitation due to greenhouse-gas-emission climate change are threatening these fragile environments. In this study, we used regional observations and downscaled data for precipitation and minimum and maximum temperature during the reference period 1960-1990 and simulations for the future period 2041-2060 to study the present and future extents of paramo ecosystems in the Chingaza National Park (CNP), nearby Colombia's capital city, Bogota. The historical data were used for establishing upper and lower precipitation and temperature boundaries to determine the locations where paramo ecosystems currently thrive. Our results found that increasing mean monthly temperatures and changing precipitation will render 39 to 52% of the current paramo extent in CNP unsuitable for these ecosystems during the dry season, and 13 to 34% during the wet season. The greatest loss of paramo area will occur during the dry season and for the representative concentration pathway (RCP) scenario 8.5, when both temperature and precipitation boundaries are more prone to be exceeded. Although our initial estimates show the future impact on paramos and the water security of Bogota due to climate change, complex internal and external interactions in paramo ecosystems make it essential to study other influencing climatic parameters (e.g., soil, topography, wind, etc.) apart from temperature and precipitation.
Hydro-climatic controls explain variations in catchment-scale nitrogen use efficiency
2020. Anna Scaini (et al.). Environmental Research Letters 15 (9)Article
The efficiency of fertilizer conversion to harvestable products is often low in annual crops such that large amounts of nutrients are lost from fields with negative consequences for the environment. Focusing on nitrogen (N) use efficiency (NUE: the ratio of N in harvested products over the sum of all N inputs), we propose that hydrological controls can explain variations in NUE, because water mediates both the uptake of N by plants and N leaching. We assess these controls at the catchment scale, at which the water balance can be constrained by precipitation and runoff data and NUE can be quantified with census data. With this approach we test the hypotheses that a higher evaporative ratio (ET/P: the ratio of evapotranspiration over precipitation) increases N retention, thereby increasing NUE both across catchments at a given time and through time. With data from 73 catchments in the United States, encompassing a wide range of pedoclimatic conditions for the period 1988-2007, we apply a linear mixed effect model to test the effect of ET/P on NUE. Supporting our hypotheses, ET/P was positively related to NUE, and NUE increased through time. Moreover, we found an interaction between ET/P and time, such that the ET/P effect on NUE decreased in the period 1998-2007. We conclude that climatic changes that increase ET/P without negatively affecting yields, will increase N retention in the examined catchments.
Hydroclimatic Effects of a Hydropower Reservoir in a Tropical Hydrological Basin
2020. David Zamora, Erasmo Rodríguez, Fernando Jaramillo. Sustainability 12 (17)Article
The consequent change in land cover from vegetation to water surface after inundation is the most obvious impact attributed to the impoundment of reservoirs and dam construction. However, river regulation also alters the magnitude and variability of water and energy fluxes and local climatic parameters. Studies in Mediterranean, temperate and boreal hydrological basins, and even a global-scale study, have found a simultaneous decrease in the variation of runoff and increase in the mean evaporative ratio after impoundment. The aim here is to study the existence of these effects on a regulated tropical basin in Colombia with long-term data, as such studies in tropical regions are scarce. As expected, we observed a decrease in the long-term coefficient of variation of runoff of 33% that can be attributed to the impoundment of the reservoir. However, we did not find important changes in precipitation or the expected increasing evaporative ratio-effect from the impoundment of the reservoir, founding for the latter rather a decrease. This may be due to the humid conditions of the region where actual evapotranspiration is already close to its potential or to other land cover changes that decrease evapotranspiration during the studied period. Our study shows that the effects from impounded reservoirs in tropical regulated basins may differ from those found in other climatic regions.
Illuminating water cycle modifications and Earth system resilience in the Anthropocene
2020. Tom Gleeson (et al.). Water resources research 56 (4)Article
Fresh water—the bloodstream of the biosphere—is at the center of the planetary drama of the Anthropocene. Water fluxes and stores regulate the Earth's climate and are essential for thriving aquatic and terrestrial ecosystems, as well as water, food, and energy security. But the water cycle is also being modified by humans at an unprecedented scale and rate. A holistic understanding of freshwater's role for Earth system resilience and the detection and monitoring of anthropogenic water cycle modifications across scales is urgent, yet existing methods and frameworks are not well suited for this. In this paper we highlight four core Earth system functions of water (hydroclimatic regulation, hydroecological regulation, storage, and transport) and key related processes. Building on systems and resilience theory, we review the evidence of regional‐scale regime shifts and disruptions of the Earth system functions of water. We then propose a framework for detecting, monitoring, and establishing safe limits to water cycle modifications and identify four possible spatially explicit methods for their quantification. In sum, this paper presents an ambitious scientific and policy grand challenge that could substantially improve our understanding of the role of water in the Earth system and cross‐scale management of water cycle modifications that would be a complementary approach to existing water management tools.
Integrating the Water Planetary Boundary With Water Management From Local to Global Scales
2020. Samuel C. Zipper (et al.). Earth's future 8 (2)Article
The planetary boundaries framework defines the safe operating space for humanity represented by nine global processes that can destabilize the Earth System if perturbed. The water planetary boundary attempts to provide a global limit to anthropogenic water cycle modifications, but it has been challenging to translate and apply it to the regional and local scales at which water problems and management typically occur. We develop a cross-scale approach by which the water planetary boundary could guide sustainable water management and governance at subglobal contexts defined by physical features (e.g., watershed or aquifer), political borders (e.g., city, nation, or group of nations), or commercial entities (e.g., corporation, trade group, or financial institution). The application of the water planetary boundary at these subglobal contexts occurs via two approaches: (i) calculating fair shares, in which local water cycle modifications are compared to that context's allocation of the global safe operating space, taking into account biophysical, socioeconomic, and ethical considerations; and (ii) defining a local safe operating space, in which interactions between water stores and Earth System components are used to define local boundaries required for sustaining the local water system in stable conditions, which we demonstrate with a case study of the Cienaga Grande de Santa Marta wetlands in Colombia. By harmonizing these two approaches, the water planetary boundary can ensure that water cycle modifications remain within both local and global boundaries and complement existing water management and governance approaches.
Radial Growth Responses to Climate of Pinus yunnanensis at Low Elevations of the Hengduan Mountains, China
2020. Lian Sun (et al.). Forests 11 (10)Article
The relationship between climate and forest is critical to understanding the influence of future climate change on terrestrial ecosystems. Research on trees at high elevations has uncovered the relationship in the Hengduan Mountains region, a critical biodiversity hotspot area in southwestern China. The relationship for the area at low elevations below 2800 m a.s.l. in the region remains unclear. In this study, we developed tree ring width chronologies of Pinus yunnanensis Franch. at five sites with elevations of 1170–1725 m in this area. Monthly precipitation, relative humidity, maximum/mean/minimum air temperature and the standardized precipitation evapotranspiration index (SPEI), a drought indicator with a multi-timescale, were used to investigate the radial growth-climate relationship. Results show that the growth of P. yunnanensis at different sites has a similar response pattern to climate variation. Relative humidity, precipitation, and air temperature in the dry season, especially in its last month (May), are critical to the radial growth of trees. Supplemental precipitation amounts and reduced mean or maximum air temperature can promote tree growth. The high correlations between chronologies and SPEI indicate that the radial growth of trees at the low elevations of the region is significantly limited by the moisture availability. Precipitation in the last month of the previous wet season determines the drought regime in the following dry seasons. In spite of some differences in the magnitudes of correlations in the low-elevation area of the Hengduan Mountains region, chronologies generally matched well with each other at different elevations, and the differences are not evident with the change in elevation.
Using InSAR to identify hydrological connectivity and barriers in a highly fragmented wetland
2020. Dan Liu (et al.). Hydrological Processes 34 (23), 4417-4430Article
Hydrological connectivity is a critical determinant of wetland functions and health, especially in wetlands that have been heavily fragmented and regulated by human activities. However, investigating hydrological connectivity in these wetlands is challenging due to the costs of high-resolution and large-scale monitoring required in order to identify hydrological barriers within the wetlands. To overcome this challenge, we here propose an interferometric synthetic aperture radar (InSAR)-based methodology to map hydrologic connectivity and identify hydrological barriers in fragmented wetlands. This methodology was applied along 70 transects across the Baiyangdian, the largest freshwater wetland in northern China, using Sentinel 1A and 1B data, covering the period 2016-2019. We generated 58 interferograms providing information on relative water level changes across the transects that showed the high coherence needed for the assessment of hydrological connectivity. We mapped the permanent and conditional (temporary) barriers affecting connectivity. In total, 11% of all transects are permanently disconnected by hydrological barriers across all interferograms and 58% of the transects are conditionally disconnected. Areas covered by reed grasslands show the most undisturbed hydrological connectivity while some of these barriers are the result of ditches and channels within the wetland and low water levels during different periods of the year. This study highlights the potential of the application of Wetland InSAR to determine hydrological connectivity and location of hydrological barriers in highly fragmented wetlands, and facilitates the study of hydrological processes from large spatial scales and long-time scales using remote sensing technique.