Climate Elasticity Research Articles

Regionalization of Climate Elasticity Preserves Dooge's Complementary Relationship

AbstractClimate elasticity of streamflow represents a nondimensional measure of the sensitivity of streamflow to climatic factors. Estimation of such elasticities from observational records has become an important alternative to scenario‐based methods of evaluating streamflow sensitivity to climate. Nearly all previous elasticity studies have used a definition of elasticity known as arc elasticity, which measures changes in streamflow about mean values of streamflow and climate. Using observational records in the western U.S., our findings reveal that elasticity definitions based on power law models lead to both regional and basin specific estimates of elasticity which are physically more realistic than estimates based on arc elasticity. Evaluating the ability of arc and power law elasticity estimators in reproducing Dooge's complementary relationship (DCR) between potential evapotranspiration and precipitation elasticities reveal that power law elasticities estimated from at‐site, panel, and hierarchical statistical models reproduce DCR, whereas corresponding estimators based on arc elasticity cannot reproduce DCR. Importantly, our regional elasticity formulations using panel and hierarchical formulations led to estimates of both regional and basin specific estimates of elasticities, enabling and contrasting streamflow sensitivity to climate across both basins and regions.

Long-term variations in ecosystem water use efficiency in the Tibetan Plateau: Vegetation types, attribution methods and main drivers

Ecosystem water use efficiency (WUE) is a key indicator for understanding the response of carbon–water processes to environmental changes. However, as affected by uncertainty of WUE estimation and attribution, the individual contributions of environmental drivers to WUE changes and the underlying mechanisms remain unclear on the Tibetan Plateau (TP). Here, a theory-based analytical WUE model was modified by introducing an optimal stomatal behavior model, and used to estimate monthly WUE and their drivers during 1982–2018 for main vegetation types on the Tibetan Plateau (TP). Rationality of three mainstream analytical attribution methods—analytical-based partial derivative method (APDM), regression-based partial derivative method (NPDM), and climate elasticity method (CEM)—was examined. Furtherly, the contributions of various environmental drivers to WUE variation trend were estimated for various vegetation types. Results indicate that: (1) The modified model performed well in estimating WUE against with observed WUE at five eddy-covariance (EC) flux stations, which decreased the uncertainty of WUE estimation. WUE increased significantly in the TP with a slope of 0.49 × 10-2 g C kg−1 H2O yr−1 during 1982–2018 with forests increased most rapidly; (2) Only APDM captured both the variation and magnitude of WUE trends, and both NPDM and CEM failed to reproduce the magnitude of WUE trends, though CEM was better than NPDM benefited from its nonlinear structure. Through comparing these methods, we found that the nonlinear direct effects of these forcing variables on WUE change could be higher than their indirect effects caused by their interactions. (3) There are some differences in the main drivers of WUE trends for various vegetation types. Increase in WUE was mainly driven by the increase in leaf area index (LAI) for both steppes and meadows, while decreased air water vapor pressure deficit (VPD) and elevated CO2 showed higher positive effects for broad-leaf forests. The distinct response and extremely scarce EC observations of forests suggest that more attention should be paid to forests in the TP. This study could help in selection of attribution methods and understanding the mechanisms of carbon–water coupling of alpine ecosystems under a changing climate.

Sensitivity of Runoff to Climatic Factors and the Attribution of Runoff Variation in the Upper Shule River, North-West China

Climate change and human activities exert significant impact on the mechanism of runoff generation and confluence. Comprehending the reasons of runoff change is crucial for the sustainable development of water resources. Taking the Upper Shule River as the research area, the M-K test and the moving t test were used to diagnose the runoff mutation time. Furthermore, the slope changing ratio of cumulative quantity method (SCRCQ), climate elasticity method, and Budyko equation were utilized to quantitatively evaluate the impacts and contribution rates of climate change and human activities. The following results were obtained: (1) The Upper Shule River experienced a significant increase in runoff from 1972 to 2021, with 1998 marking the year of abrupt change. (2) The runoff sensitivity showed a downward trend from 1972 to 2021. The main factor affecting the decrease in runoff sensitivity was the characteristic parameters of underlying surface (n), followed by precipitation (P), while the influence of potential evapotranspiration (ET0) was the weakest. (3) The response of runoff changes to runoff sensitivity and influencing factors were 90.32% and 9.68%, respectively. (4) The results of three attribution methods indicated that climate change was the primary factor causing the alteration of runoff in the Upper Shule River. The research results supplement the hydrological change mechanisms of the Upper Shule River and provide a scientific basis for future water resources management and flood control measures.

Contribution of climate and catchment characteristics to runoff variations in Indian river basins: a climate elasticity approach

ABSTRACT The relative influence of climate and catchment characteristics to the variations in runoff in five Indian river basins is assessed using the climate elasticity approach based on the Budyko hypothesis. From 1980 to 1999, catchment characteristics are found to be the main contributor to runoff variation for all of the basins except Upper Mahanadi sub-basin, where climatic factors are the major contributor. Among the climatic factors, runoff is more responsive to changes in precipitation than to changes in potential evapotranspiration. The mean contribution of climate (catchment) to runoff variation is largest at the Cauvery (Krishna) basin. The findings may be useful in planning sustainable water resources infrastructure. Investigation of the relationship between runoff changes in the basins and their land use and land cover changes, as well as the vegetation index, adds to the novelty and usefulness of the study.

Climate elasticity assessment on groundwater recharge to the Edwards Balcones Fault Zone Aquifer, United States

AbstractThis study presents a comprehensive analysis of the characteristics of precipitation, temperature, and groundwater recharge in the recharge zone of the nine basins of the San Antonio segment of the Edwards Balcones Fault Zone Aquifer, which is one of the major groundwater systems in the United States and serves as primary water sources for approximately 1.7 million people in south‐central Texas. Datasets of monthly precipitation and average temperature (1895–2019) and groundwater recharge (1934–2019) are used to examine the decadal variability in precipitation, temperature, and groundwater recharge on the annual scale with a normalized 20‐year moving average of variance. Climate elasticity (precipitation and potential evapotranspiration) of groundwater recharge is estimated to evaluate impacts of climate change on groundwater recharge. The results of this study show that precipitation and temperature variability exhibit decadal cyclic patterns. Elasticity analysis of groundwater recharge indicates that a 1% change in annual precipitation may result in 2%, with a likely range of 0.15%–2.8%, change in groundwater recharge, and a 1% change in annual potential evapotranspiration may lead to −3.3% change in groundwater recharge with a likely range of −8.9% to 4% in the study area. This study suggests that climate elasticity of groundwater recharge may provide an alternative means for evaluating climate impacts on groundwater recharge to an aquifer.

Enhancing Streamflow Modeling by Integrating GRACE Data and Shared Socio-Economic Pathways (SSPs) with SWAT in Hongshui River Basin, China

Climatic variability and the quantification of climate change impacts on hydrological parameters are persistently uncertain. Remote sensing aids valuable information to streamflow estimations and hydrological parameter projections. However, few studies have been implemented using remote sensing and CMIP6 data embedded with hydrological modeling. This research studied how changing climate influences the hydro-climatic parameters based on the earth system models that participated in the sixth phase of the Coupled Model Intercomparison Project (CMIP6). GRACE evapotranspiration data were forced into the Soil and Water Assessment Tool (SWAT) to project hydrologic responses to future climatic conditions in the Hongshui River basin (HRB) model. A novel approach based on climate elasticity was utilized to determine the extent to which climate variability affects stream flow. CMIP6 SSPs (shared socio-economic pathways) for the second half of the 20th century (1960–2020) and 21st century (2021–2100) projected precipitation (5–16%) for the whole Hongshui River basin (HRB). The ensemble of GCMs projected an increase of 2 °C in mean temperature. The stream flow is projected to increase by 4.2% under SSP-1.26, 6.2% under SSP-2.45, 8.45% under SSP-3.70, and 9.5% under SSP-5.85, based on the average changes throughout the various long-term future scenarios. We used the climate elasticity method and found that climate change contributes 11% to streamflow variability in the Hongshui River basin (HRB). Despite the uncertainty in projected hydrological variables, most members of the modeling ensemble present encouraging findings for future methods of water resource management.

Climate Elasticity of Annual Runoff: Observation in Fifteen Forested Catchments on a Latitudinal Gradient in East Asia

In order to overview the impact of climate change on runoff from forested catchments over Asian countries, we collected water balance data from fifteen long-term catchment monitoring stations (total monitoring period 1975–2018, not continuous), spanning from Sabah, Malaysia (our southernmost site), to Hokkaido, Japan (our northernmost site). We then employed an elasticity analysis to the dataset to examine how the annual runoff from each catchment responded to inter-annual fluctuations in annual rainfall and annual mean air temperature. As a result, we found that (1) the annual runoff was sensitive to annual rainfall for all the catchments examined. In addition, (2) the annual runoff from seven of the fifteen catchments was sensitive to inter-annual changes in the mean air temperature, which was likely due to changes in forest evapotranspiration. Three catchments, however, exhibited an increased runoff in a hot year. Finally, (3) the annual rainfall from the previous year (carry-over soil moisture) was important in explaining the variation in annual runoff in two tropical montane forest catchments. This study may serve as one of the pilot studies toward a comprehensive understanding of the climate elasticity of runoff in countries over Asia, because the examined catchments are unevenly and sparsely distributed over the area.

Streamflow Composition and the Contradicting Impacts of Anthropogenic Activities and Climatic Change on Streamflow in the Amu Darya Basin, Central Asia

Abstract Transboundary rivers are often the cause of water-related international disputes. One example is the Amu Darya River, with a catchment area of 470 000 km2, which passes through five countries and provides water resources for 89 million people. Intensified human activities and climate change in this region have altered hydrological processes and led to water-related conflicts and ecosystem degradation. Understanding streamflow composition and quantifying the change impacts on streamflow in the Amu Darya basin (ADB) are imperative to water resources management. Here, a degree-day glacier-melt scheme coupled offline with the Variable Infiltration Capacity hydrological model (VIC-glacier), forced by daily precipitation, maximum and minimum air temperature, and wind speed, is used to examine streamflow composition and changes during 1953–2019. Results show large differences in streamflow composition among the tributaries. There is a decrease in the snowmelt component (−260.8 m3 s−1) and rainfall component (−30.1 m3 s−1) at Kerki but an increase in the glacier melt component (160.0 m3 s−1) during drought years. In contrast, there is an increase in the snowmelt component (378.6 m3 s−1) and rainfall component (12.0 m3 s−1) but a decrease in the glacier melt component (−201.8 m3 s−1) during wet years. Using the VIC-glacier and climate elasticity approach, impacts of human activities and climate change on streamflow at Kerki and Kiziljar during 1956–2015 are quantified. Both methods agree and show a dominant role played by human activities in streamflow reduction, with contributions ranging 103.2%–122.1%; however, the contribution of climate change ranges from −22.1% to −3.2%.

Determining the spatial contributions of land use changes on the streamflow and sediment transport regimes: a case study of the Gorganroud watershed in Iran.

Human activities and climate change are recognized as two of the most important drivers of hydrologic variability and have attracted the interest of researchers over the past decade. Changes in land use, dam construction, agricultural development, and global warming are forces that directly or indirectly impact the global and local hydrologic regime. This study examines the effects of these drivers on streamflow and sediment transport in the Gorganroud watershed, located in the north of Iran. In addition, the most sensitive land use patterns are detected using statistical approaches and a hydrologic model. The current study's principal argument is based on the variability of land use patterns during the modeling procedure (2007-2019). The Soil and Water Assessment Tool (SWAT) model is used to consider the land use dynamics during the simulation period based on the hydrological regime of the reference period. The Simple Differential Method (SDM) and Climate Elasticity Method (CEM) are utilized to estimate the contribution rates of land use and climate change in streamflow and sediment transport changes. The results indicate that changes in land use have contributed more than 60% to streamflow and sediment regime changes in all subbasins. A sensitivity analysis of land uses and the spatial distribution of the Human Contribution Rate (HCR) over the study area reveal that an increase in orchard land use (8.7% during the computational period) is primarily responsible for these significant changes.

Effect of land use change on climate elasticity of water quality at multiple spatial scales

Abstract Investigating the influence of land use change on climate elasticity of water quality (CEWQ) at multiple spatial scales is very critical for sustainable water management policies. The current research work investigated land use change–water–climate nexus through the lens of 32 water quality monitoring sites located at major rivers of Pakistan. The novelty of the current research work is the assessment of the instability consequences of precipitation and temperature CEWQ indicators owing to land use dynamics (2001–2019) at both sub-watershed and buffer scales. Precipitation elasticity values are lower and spatially homogeneous in comparison with temperature elasticity. Majority CEWQ-land use correlation coefficients have not shown any temporal trend with land use change except a few CEWQ indicators, namely pH, CO3, F, Ca, SiO2, silt, and clay. Temperature CEWQ developed many linear models with land use in comparison with precipitation CEWQ. A small number of land use classes cause instability consequences at the buffer scale in comparison with the sub-watershed scale. Savanna, shrublands, and ice and snow decline instability consequences of CEWQ indicators at both spatial scales. The identified land use classes that bring stability in CEWQ indicators are recommended to be incorporated in watershed management policies to bring sustainability in the aquatic environment.

Anthropic Changes in Land Use and Land Cover and Their Impacts on the Hydrological Variables of the São Francisco River Basin, Brazil

The growing impact of human activities on the environment has increased their influence on the planet’s natural cycles, especially in relation to the hydrological cycle of watersheds. The fundamental processes for its water and energy balance have been affected, which influences water availability and surface streamflow. This study sought to evaluate the anthropogenic impacts on the hydrological cycle of the São Francisco River Basin (SFRB), Brazil, between 1985 and 2015. The study area comprised SFRB and 10 sub-basins for general and specific analyses, respectively. Analyzed data consisted of Land Use and Land Cover (LULC), precipitation, streamflow, and temperature. The methodology incorporated: (i) assessment of LULC dynamics; (ii) trend analysis with the Mann–Kendall method and Sen’s Slope; and (iii) decomposition of total streamflow variation via Budyko’s hypothesis and climate elasticity of streamflow. As a result, it was possible to detect an anthropic modification of SFRB, which is the main component of its streamflow variation, in addition to increased streamflow sensitivity to climate variations. In addition, the divergent behavior in the trends of hydrological variables suggests a change in the streamflow response to precipitation. Therefore, the results allowed us to identify and quantify the impacts of anthropic modifications on the hydrological cycle of the SFRB.

Estimation of climatic and anthropogenic contributions to streamflow change in southern Romania

ABSTRACT This research investigated the contributions of climate- and human-induced change to streamflow alteration between 1966 and 2010 in four catchments in southern Romania (Vedea, Argeș, Ialomița and Buzău). We examined trends and break points in streamflow, precipitation and potential evapotranspiration and we estimated climate elasticity with Fu’s equation within the Budyko framework to further separate the contributions of climate and human changes to streamflow alterations. Results showed break points in streamflow in all catchments between 1981 and 1985, followed by decreases in average annual streamflow that varied between −28.1% and −53.4%. Most of the streamflow decline was found to be due to climate contribution: 63.1% in Argeș (the most anthropized catchment), 71.2% in Buzău, 79.2% in Ialomița and 80.2% in Vedea basin. Due to the environmental changes impacting water resources in Romania, estimating the contribution of the main drivers of streamflow change is highly important for their sustainable management.

Trends and Climate Elasticity of Streamflow in South-Eastern Brazil Basins

Trends in streamflow, rainfall and potential evapotranspiration (PET) time series, from 1970 to 2017, were assessed for five important hydrological basins in Southeastern Brazil. The concept of elasticity was also used to assess the streamflow sensitivity to changes in climate variables, for annual data and 5-, 10- and 20-year moving averages. Significant negative trends in streamflow and rainfall and significant increasing trend in PET were detected. For annual analysis, elasticity revealed that 1% decrease in rainfall resulted in 1.21–2.19% decrease in streamflow, while 1% increase in PET induced different reductions percentages in streamflow, ranging from 2.45% to 9.67%. When both PET and rainfall were computed to calculate the elasticity, results were positive for some basins. Elasticity analysis considering 20-year moving averages revealed that impacts on the streamflow were cumulative: 1% decrease in rainfall resulted in 1.83–4.75% decrease in streamflow, while 1% increase in PET induced 3.47–28.3% decrease in streamflow. This different temporal response may be associated with the hydrological memory of the basins. Streamflow appears to be more sensitive in less rainy basins. This study provides useful information to support strategic government decisions, especially when the security of water resources and drought mitigation are considered in face of climate change.

Investigation of the Effects of Climate Variability, Anthropogenic Activities, and Climate Change on Streamflow Using Multi-Model Ensembles

Streamflow is a very important component of the hydrological cycle, and variation in the streamflow can be an indication of hydrological disaster. Thus, the accurate quantification of streamflow variation is a core concern in water resources engineering. In this study, we evaluated the factors influencing streamflow and decomposed their effects in three large rivers: the Buk Han River (BHR), the Nam Han River (NHR), and the Lower Han River (LHB). The Pettit test was used to investigate breakpoints in conjunction with the climate elasticity approach and decomposition framework to quantify and decompose the effects of climate variability and anthropogenic activity. The abrupt breakpoints in the streamflow and precipitation data were detected in 1997 and 1995. Considering these breakpoints, we divided the time series into two periods: the baseline period and the post-baseline period. Climate elasticity approaches were used to quantify the effects of climate variability and anthropogenic activity during the baseline period, post-baseline period, and future periods (2031–2060 and 2071–2100) under the Representative Concentration Pathways’ 4.5 and 8.5 scenarios. The results revealed that climate variability was the leading cause of alteration in the streamflow in the BHR and NHR, accounting for 76.52% to 80.51% of the total change, respectively. Meanwhile, the LHR remained more sensitive to anthropogenic activity, which accounted for 56.42% of the total variation in streamflow. Future climate change also showed an increase in precipitation and temperature in both scenarios, especially during the far-future period (2071–2100). This variation in the climatic factor was shown to affect the future streamflow by 22.14% to 27.32%. These findings can play a very important role in future planning for large river basins, considering the impacts of increasing anthropogenic activity and climate change to reduce the risks of hydrological hazards.

Spatiotemporal variations in the elasticity of runoff to climate change and catchment characteristics with multi-timescales across the contiguous United States

Abstract There is a lack of understanding of the impact of timescales on runoff elasticity. In this study, gauged river flow and meteorological data time-series from 1916 to 2015 and 1941 to 2015 across the contiguous United States (CONUS) for 188 catchments were collected. We studied spatiotemporal variations of climate and catchment elasticity at multi-timescales (11, 20, 40, and 60 a) across the CONUS, and the relationships between the elasticity of runoff and climatic factors were also analyzed. Median descriptive statistics and Budyko-coupled climate elasticity methods were used to calculate runoff elasticity in each timescale. The original Mann–Kendall trend test was used to test the temporal trend significance in four timescales, respectively. The results show that (1) the trend and values of runoff elasticity may not be affected by timescales. (2) Catchment characteristics in some western regions may be the second-most sensitive factor for runoff following the maximum temperature. The roles of potential evaporation, maximum temperature, and catchment characteristics on runoff gradually become important from east to west. (3) Runoff elasticity is independent of precipitation, and wet regions tend to have lower elasticity of runoff. There are strong relationships between elasticity and most factors, except for precipitation, which can illustrate well its spatial pattern.

On the attribution of changing water surface evaporation across China

Study regionChina Study focusWater evaporation represents a pivotal indicator of the terrestrial ecosystem and hydrological cycle, influencing regional water and energy balance to some extent. In this study, the long-term data series of water surface evaporation (Ep) were assimilated across China, with the observations from 552 national benchmark weather stations. The trends of Ep and the influential climate variables were well detected. The analytical derivation method was built up to quantitatively attribute the effects from 5 key climate fields to Ep variations, including wind speed (u2), sunshine duration (n), relative humidity (RH), daily maximum (Tmax), and minimum (Tmin) air temperature. New hydrological insights for the regionThe attribution results were more accurate and reasonable than those from two commonly used statistically based climate elasticity methods, which tended to overestimated the Ep variations. Most weather stations had experienced the decreasing trends of Ep during the entire research period of 1961–2018, which were mainly attributed to the decreasing in u2, n and RH, while the effects of regional warming (rising air temperature) were less influential on Ep variations at the long-term scale. The variations of Ep attributed to the three main influential climate variables (u2, n and RH) across China had also shown different temporal and spatial tendency patterns during different historical research periods. For example, the changing n and RH had shown increasing power on Ep variations in the western China climate zones. Comparatively, the u2 has been losing its power in decreasing Ep in most regions of China due to the slowdown in the declining rates of wind speed. This dynamic Ep attribution process is worthy of continuous focus and systematic research.

The role of climate change and human interventions in affecting watershed runoff responses

AbstractIdentifying the role of the two main driving factors—climate change and human interventions—in influencing runoff processes is essential for sustainable water resources management. For this purpose, runoff regime change detection methods were used to divide the available hydroclimatic variables into a baseline and a disturbed period. We applied hydrological modelling and the climate elasticity of runoff method to determine the contribution of climate change and human interventions to changes in runoff. The hydrological model, SWAT, was calibrated during the baseline period and used to simulate the naturalized runoff pattern for the disturbed period. Significant changes in runoff in the study watershed were detected from 1982, suggesting that human interventions play a dominant role in influencing runoff. The combined effects of climate change and human interventions resulted in a 41.3 mm (23.9%) decrease in runoff during the disturbed period, contributing about 40% and 60% to the total runoff change, respectively. Furthermore, analysis of changes in land cover dynamics in the watershed over the past four decades supported these changes in runoff. Contrary to other decades, the discrepancy between naturalized and observed runoff was small in the 2010s, likely due to increased baseflow as a result of storage and/or release of excess water during the dry season. This study contributes to our understanding of how climate change and human interventions affect hydrological responses of watersheds, which is important for future sustainable water management and drought adaptation.

Evaluation of Climate Elasticity of Runoff based on Observed Rainfall, Streamflow and Simulated Future Streamflow using SWAT Model in Kelani Ganga Basin

"ENGINEER", established in 1973 by The Institution of Engineers, is a Journal for dissemination of Engineering knowledge, published quarterly.If you are interested in contributing an Original Technical Paper based on research by the author(s) (intended for Section I) or an Original Article of Professional or Technical interest related to Engineering. (Section II) to this journal please go through the publication checklist which can be downloaded from here.Cover DescriptionCover images show a few views of Stage II of the Central Expressway from Mirigama to Kurunegala. The Institution of Engineers Sri Lanka acknowledges the Road Development Authority (RDA) for the images.

Temporal and Spatial Changes of Runoff Regime in the Yellow River Basin from 1956 to 2017

The Yellow River is one of the major rivers with severe runoff declines in China, but there are significant differences in runoff changes in the upper and lower reaches of the basin and among different tributaries. However, the characteristic of runoff change and its spatial heterogeneity are not well understood in the whole basin. In this paper, 48 hydrological stations located in the mainstream and major tributaries were selected, and the meteorological and runoff data from 1956 to 2017 were collected. The multi-year and intra-year changes in runoff were analyzed, and then the attribution of climate change and human activity to runoff change was quantified by the climate elasticity coefficients. The results showed that: (1) in the past 60 years, the runoff of the Yellow River showed a serious decrease trend of −8.25 mm/10a. Moreover, most tributaries decreased significantly in runoff with a rate of −1.42 mm/10a to −28.99 mm/10a; (2) for the whole basin, the contribution of climate change and human activity to runoff changes was 13% and 87%, respectively. Moreover, the contribution of the two factors varied considerably in different tributaries. Finally, focusing on different runoff regime and socioeconomic characteristics, this study provided corresponding water resources adaptive management suggestions.

Runoff responses to human activities and climate change in an arid watershed of central Iran

ABSTRACT In this study, contributions of climate change and human activity to streamflow changes were estimated to enable decision makers to develop adaptation strategies for management of regional water resources. Flow trends and climate variables were analysed with the Mann-Kendall method. The year 1986 was selected to perform the Pettitt test to identify the change point of the runoff time series. Then, three methods were used for impact differentiation: climatic elasticity, least-squares support-vector machine (LS-SVM), and the soil and water assessment tool (SWAT). The results showed that climate change (38–67%) and human activities (33–62%) influence runoff reduction. Thus three management scenarios are introduced to reduce the effects of climate change and human activity: (1) adjusting wheat and barley cultivation levels; (2) maintaining wheat and barley cultivation levels and replacing other crops with potatoes; (3) increasing irrigation efficiency. All scenarios showed an increase in runoff, but the first scenario had the most impact.