Post-change Period Research Articles

Evaluation of Isopropyl Alcohol Aromatherapy in Treating Nausea in Helicopter Emergency Medical Services Patients

ObjectiveIsopropyl alcohol (IPA) aromatherapy provides rapid relief of nausea at minimal cost, is universally available, and has no known significant adverse effects. These attributes make it ideal for the prehospital setting. However, there is no published research on the use of IPA in critical care transport (CCT). The objective of this study was to investigate if CCT patients experience improvement of nausea with IPA aromatherapy. MethodsA retrospective chart review was performed over a 2-year period on adult patients served by a Midwest CCT system that provides both air and ground transport. Data were obtained 1 year before and 1 year after a protocol change in which the first-line antiemetic was changed from intravenous ondansetron (prechange) to inhaled IPA (postchange). The IPA was administered by placing a pad under the patient's nares as they inhaled. The proportion of nausea improvement was compared between the prechange and postchange periods. ResultsTwo hundred seventeen records were included. In helicopter emergency medical services, 33 of 50 (66.0%) patients reported improvement with ondansetron, and 13 of 21 (61.9%) reported improvement with IPA (P = .742). Patients transported by ground emergency medical services showed improvement in 65 of 73 (89.0%) cases for ondansetron and 40 of 73 (54.8%) for IPA (P < .001). ConclusionThere was no difference in the proportion of nausea improvement between ondansetron and IPA in helicopter emergency medical services patients. In ground emergency medical services patients, more patients had nausea improvement with ondansetron compared with IPA. This study suggests IPA may be a faster, more efficacious alternative for nausea relief in CCT patients.

A Living Lab approach for sustainable intensification of dairy production: A case study of an organic and a conventional farm in northern Italy

Working on feed production and feeding strategies is one of the key ways of mitigating dairy impacts and of increasing dairy efficiency and the nutritional quality of milk, all of which are priorities for global dairy sector stakeholders. Feed production, both on farm and off-farm, is one of the main contributors to dairy farm greenhouse gas (GHG) emissions, and it is known that the adopted feeding strategies influence farm nutrient balance, nutrient losses to the environment, and milk fatty acid profile. This study has been aimed at improving farm efficiency, environmental sustainability, and milk nutritional quality by acting on the management of the cropping system, and by promoting the on-farm production of feeds of high nutritional quality and high fiber digestibility in order to improve the self-sufficiency of metabolizable energy (ME) and protein (CP) for animal feeding. A multi-year study was conducted to analyze the shift in cropping system management on an organic farm and on a conventional dairy farm, considered as a “lighthouses”, and which were part of a Living Lab. Two 3-year pre-change periods (PRE) and two 3-year post-change periods (POST) with 2 years of transition were considered. The main actions performed on the management of the forage system involved changes in the crop destination, in the harvest schedule and in the conservation methods. All the data necessary to determine the dry matter (DM) yield, the forage quality, in terms of crude protein (CP), the metabolizable energy (ME), the nitrogen balance, and the carbon footprint of the two farms were measured or collected on farm. One kg of fat and protein corrected milk (FPCM) was used as a functional unit. In the POST periods, the milk production intensity (t FPCM/ha) improved and the ME and CP self-sufficiency of the heard increased on both farms. Both farms showed a 9.8% reduction of the Carbon Footprint (CF), and a reduction in the nitrogen surplus at the farm level. The amounts of C18:3 n-3 and n-3 fatty acids increased on both farms in the POST period. The results of this work show that it is possible to intensify milk production and mitigate the impacts of dairy farms by acting on the management of the forage system and on the feed strategies, using a synergistic Living Lab approach to achieve sustainable intensification.

Interaction of Climate Change and Anthropogenic Activity on the Spatiotemporal Changes of Surface Water Area in Horqin Sandy Land, China

Surface water dynamics are sensitive to climate change and anthropogenic activity, and they exert important feedback to the above two processes. However, it is unclear how climate and human activity affect surface water variation, especially in semi-arid regions, such as Horqin Sandy Land (HQSL), a typical part of the fragile region for intensive interaction of climate and land use change in northern China. We investigated the changes of spatiotemporal distribution and the influence of climatic and anthropogenic factors on Surface Water Area (SWA) in HQSL. There are 5933 Landsat images used in this research, which were processed on the Google Earth Engine cloud platform to extract water bodies by vegetation index and water index method. The results revealed that the area and number of water bodies showed a significant decrease in HQSL from 1985 to 2020. Spatially, the SWA experienced different amplitudes of variation in the Animal Husbandry Dominated Region (AHDR) and in the Agriculture Dominated Region (ADR) during two periods; many water bodies even dried up and disappeared in HQSL. Hierarchical partitioning analysis showed that the SWA of both regions was primarily influenced by climatic factors during the pre-change period (1985–2000; the mutation occurred in 2000), and human activity has become more and more significantly important during the post-change period (2001–2020). Thus, it is predictable that SWA variation in the following decades will be influenced by the interaction of climate change and human activity, even more by the later in HQSL, and the social sectors have to improve their ability to adapt to climate change by modifying land use strategy and techniques toward the sustainable development of water resources.

Sequential Detection of an Arbitrary Transient Change Profile by the FMA Test

This article addresses the sequential detection of transient changes by using the finite moving average (FMA) test. It is assumed that a change occurs at an unknown (but nonrandom) change point and the duration of postchange period is finite and known. We relax the assumption that the profile of a transient change is chosen so that the log-likelihood ratios of the observations are associated random variables (r.v.s) in the prechange mode. Hence, the profile of the transient change is arbitrary and it is not necessarily of constant sign for a distribution with monotone likelihood ratio. A new upper bound for the worst-case probability of false alarm is proposed. It is shown that the optimization of the window-limited cumulative sum (CUSUM) test again leads to the FMA test. Three particular transient changes are considered: in the Gaussian mean, in the Gaussian variance, and in the parameter of exponential distribution. In the first case, a comparison between the bounds for the FMA test operating characteristics and the exact operating characteristics calculated by numerical integration is used to estimate the sharpness of the bounds. In the second and third cases, special attention is paid to the calculation of the FMA distribution in the case of arbitrary profile. The method of convolution is used to solve the problem.

The Association Between Catheter Type and Dialysis Treatment: A Retrospective Data Analysis at Two U.S.-Based ICUs.

To evaluate the association between the catheter type and multiple dialysis treatment outcomes among the critically ill. Retrospective, observational study. Two U.S.-based ICUs. Critically ill patients receiving CRRT between April 1, 2018, and July 1, 2020. A total of 1,037 CRRT sessions were analyzed. Circuit life, alarm interruption frequency (including a subset of vascular access [VA]-related alarms), termination type (elective vs nonelective), and blood flow rates. Pre- (n = 530) and post-catheter change (n = 507) periods were assessed, and the post-change period was further divided into intervals of pre-COVID (n = 167) and COVID contemporaneous (n = 340) to account for the pandemic's impact. Compared with pre-change sessions, post-change sessions had 31% longer circuit life (95% CI, 1.14-1.49; p < 0.001), 3% higher blood flow rate (1.01-1.05; p < 0.01), and lower proportion of nonelective terminations (adjusted odds ratio [OR], 0.42 [0.28-0.62]; p < 0.001). There were fewer interruptions for all alarms (adjusted count ratio, 0.95 [0.87-1.05]; p = 0.31) and VA-related alarms (0.80 [0.66-0.96]; p = 0.014). The sessions during COVID period were statistically similar to pre-COVID sessions for all outcomes except a lower proportion of nonelective terminations (adjusted OR, 0.39 [0.22-0.70]; p < 0.01). A change in catheter type was associated with longer CRRT sessions with fewer interruptions and unexpected terminations in a population of critical patients.

Financial and Safety Impact of Simulation-based Clinical Systems Testing on Pediatric Trauma Center Transitions.

Introduction:Simulation offers multiple tools that apply to medical settings, but little is known about the application of simulation to pediatric trauma workflow changes. Our institution recently underwent significant clinical changes in becoming an independent pediatric trauma center. We used a simulation-based clinical systems testing (SbCST) approach to manage change-associated risks. The purpose of this study was to describe our SbCST process, evaluate its impact on patient safety, and estimate financial costs and benefits.Methods:SbCST consisted of the following steps: (1) change-based needs assessment, in which stakeholders developed relevant simulation scenarios; (2) scenario implementation; and (3) postsimulation failure mode and effects analysis (FMEA) to identify latent safety threats (LSTs). LSTs were prioritized for mitigation based on the expected probability and severity of adverse event occurrences. We calculated the costs associated with the simulation process. We conservatively estimated SbCST cost savings using 3 approaches: (1) FMEA-based avoidance of adverse events; (2) avoidance of trauma readmissions; and (3) avoidance of medical liability lawsuits.Results:We implemented 2 simulation scenarios prechange. FMEA revealed 49 LSTs, of which 9 were highest priority (catastrophic severity and high likelihood of occurrence). These were prioritized and mitigated using the hospital’s quality/safety framework. Cost-benefit analysis based on FMEA event avoidance demonstrated net cost savings to the institution ranging from $52,000−227,000 over the 3-month postchange period. Readmission-based and liability-based estimates also produced favorable results.Conclusions:The SbCST approach identified multiple high-impact safety risks and financially benefited the institution in managing significant pediatric trauma clinical process changes.

Separating anthropogenic and climate contributions to streamflow variations in Rietspruit sub-basin, South Africa

Human activities and climate change continue to alter streamflow in many river basins. In this study, the influence of human activities and climate variability on streamflow changes in the Rietspruit sub-basin (RSB), South Africa, were investigated using precipitation, potential evapotranspiration, and discharge data for the period 1986 to 2018. Trends in the hydrometeorological variables were assessed using the Mann-Kendall test while the change point in the annual streamflow data was identified using the Pettitt test and the double mass curve technique. Results revealed no statistically significant change in annual precipitation, whereas annual streamflow showed a significant increasing trend while potential evapotranspiration showed a decreasing trend. It was identified that the change point occurred around 1999, thereby dividing the streamflow data into the pre-change (1986–1999) period with comparatively low urban cover (8.3%), and the post-change period (2000–2018) with urban land covering 16.6% of the study area. The results demonstrate that from 1986 to 2018, the elasticity of streamflow with respect to precipitation and potential evapotranspiration was 0.26 and −2.01, respectively. This implies that streamflow in the study area is more sensitive to potential evapotranspiration than precipitation. Nonetheless, changes in land use/land cover, particularly the urban settlement which increased by 101% between 1986 and 2018, were more influential than climate variability for the significant increase in streamflow in the RSB. The results provide necessary information for water resource management, land use planning and ecosystem development in the near future. This study emphasizes the necessity of addressing nonlinear and dynamic hydrological processes as a result of human impact and climate associated changes.

Improved clinical outcome after PK-Guided Personalised Prophylaxis with my-PKFIT® in patients with hemophilia A without inhibitors

Objective: Prophylaxis is the gold standard in patients with severe hemophilia. In recent years, personalisation of prophylaxis treatment according to pharmacokinetic properties has been used in treatment. In this study, personalisation treatment experience based on the pharmacokinetic dosing tool my-PKfit results in pediatric and adult patients from three centers is shared. Material and Methods: myPKfit (www1.mypkfit.com) was used to evaluate pharmacokinetic parameters in hemophilia A patients receiving recombinant Factor VIII (Takeda Advate ®) prophylaxis. 75 samples in 34 patients (3 samples in 7 patients, 2 samples in 27 patients) were analysed for pharmacokinetic evaluation. Age, weight and baseline FVIII level of the patients were recorded. Pharmacokinetic curves were obtained after entering sampling times, factor dose and sample results. The annual bleeding rate (ABR) of the patients were evaluated before and after the changes made after the pharmacokinetic evaluation. Results: The median age of 34 patients with severe hemophilia A without inhibitors was 12.3±8.7 (1.5-37) years, and the mean weight was 40.0±22.0 (10-83) kg. All patients had a baseline FVIII level of less than or equal to 2 IU/dl. All patients were receiving primary or secondary/tertiary prophylaxis. The mean half-life of the factors of the patients was 9.6±1.4 (7.0-13.4) hours, and the mean time reached below 1 IU/dl was 48.9±11.2 (16.0-77.0) hours. Prophylactic factor therapy was changed in 17 patients after myPKfit, dose increased in 9 patients, the frequency increased in 6 patients, and both dose and frequency increased in 2 patients. With a mean follow-up period of 23.7 +16 (2-49) months, in 17 patients whose prophylaxis regimen was changed after the PK evaluation by myPkyfit, ABR was found to be significantly lower in the post-change period, compared to the last one year before the change of regimen (2.94 + 2.19 and 0.58 + 1.00 respectively) P: 0.028. Discussion: A pharmacokinetic study by the Bayesian method is an increasingly used method for personalised prophylaxis regimen. We believe that myPKfit is beneficial in providing effective and appropriate prophylaxis.

Base Flow Variation and Attribution Analysis Based on the Budyko Theory in the Weihe River Basin

The composition and change of runoff are closely related to climate change and human activities. To design effective watershed water resources management measures, there is a need for a clear understanding of the impact of climate change and human activities on baseflow and surface runoff. The purpose of this essay is to quantify their impact on the annual total stream flow, surface runoff, and base flow in the Weihe River Basin (WRB) using a two-stage annual precipitation partitioning method, wherein the surface runoff and base flow are separated from the measured total flow by using a one-parameter digital filter method for which the common filter parameter value is 0.925. The stream flow records were split into two periods: 1960–1970 (pre-change period) and 1971–2005 (post-change period) based on the hydrological breakpoints detected. We found that climate change and human activities have different impacts on base flow and surface runoff. We attributed the decrease in surface runoff due to climate change accounting for 76–78%, while we determined that human activities were responsible to the decrease in base flow accounting for 59–73% of the total observed change. We concluded that both climate change and human beings contributed to the hydrologic change through different hydrological processes: climate change dominated the surface runoff change, while human influences controlled the base flow change. To achieve the expected goals of ecological restoration, appropriate measures must be taken by watershed management in the WRB to mitigate the likely impacts of climate change on water hydrology.

THE EFFECT OF ADOPTION OF IFRS BASED ACCOUNTING STANDARDS: INDIAN EVIDENCES OF ENHANCED VALUE RELEVANCE AND UNIFORMITY

This study examines how relevant the accounting information was for the value of the firm prior to 2016, when India had the indigenous Accounting Standards, and after 2016 when India adopted new accounting standards known as IND-AS, which were the convergence standards mostly in line with IFRS. As an extension to this, we have performed another round of analysis to observe whether the enhanced value relevance is symmetrically distributed among big and small firms. We have used the price regression model of (Barth et al, 2008) on 1770 firm-years data of Indian firms and applied panel data analysis. We have found 66% adjusted R2 under OLS method for the period prior to 2016 and 78% for the post-change period. Further to this, big and small firms, in the new regime, have shown 84% and 89% adjusted R2. From the results, we have found substantial improvement in value relevance of accounting information in the IND-AS period. We have also found that the enhanced value relevance is uniformly distributed across firms irrespective of firm-size.

Exploring the Factors Affecting Streamflow Conditions in the Han River Basin from a Regional Perspective

Considerable attention has recently been focused on the impacts of climate change and human activities on river streamflow conditions. This study explored these effects using three hydrological modeling techniques such as multi-regression, a two-parameter hydrological model, and hydrological sensitivity analysis, followed by trend analysis and change point detection. The non-parametric Mann-Kendall test was used to analyze the trends in hydro-meteorological parameters. The non-parametric Pettitt test and double cumulative curve techniques were used to identify change points in annual streamflow series during 1978–2014. After determining the change point year to be 1997, the series were split into two parts: a pre-change (natural) period (1978–1997) and a post-change (human-induced) period (1998–2014). The hydrological models were calibrated and estimated for the pre-change (natural) period, which provided the relative change in annual streamflow for the post-change (human-induced) period. The contribution of climate variability ranged from 36.3% to 55.9%, and human activities accounted for 44.5% to 63.7% of streamflow variability. These results suggest that human activities are more impactful than climate variability. The outcomes of this study show that streamflow in the basin was influenced by climate variability, but human actions were also major driving forces in altering the streamflow.

Allocation changes in heart transplantation: What has really changed?

ObjectiveIn 2018, the heart allocation system changed status classifications and broadened geographic distribution. We examined this change at a national level based on the immediate pre- and postchange periods. MethodsUsing the Scientific Registry of Transplant Recipients database, we identified all adult primary, isolated heart transplants from October 18, 2017, to October 17, 2019. Two time periods were compared: (1) October 18, 2017, to October 17, 2018 (pre); and (2) October 18, 2018, to October 17, 2019 (post). Comparisons were made between groups, and a multivariable logistic regression model was created to identify factors associated with pretransplant temporary mechanical circulatory support. Volume analysis at the regional, state, and center level was also conducted as the primary focus. ResultsA total of 5381 independent heart transplants were identified within the time frame. On unadjusted analysis, there was a significant increase in temporary mechanical circulatory support (pre, 11.1%; post, 36.2%, P < .01) and decrease in waitlist days (pre, 93 days; post, 41 days; P < .01). Distance traveled (nautical miles) (pre, 83; post, 225; P < .01) and ischemic time (hours) (pre, 3.0; post, 3.4; P < .01) were significantly increased. On multivariable analysis, the postallocation time period was independently associated with temporary MCS (odds ratio, 4.463; 95% confidence interval, 3.844-5.183; P < .001). Transplant volumes did not significantly change after the allocation change at a regional, state, and center level. ConclusionsSince the planned alteration to the allocation system, there have been changes in the use of temporary mechanical circulatory support as well as distance and ischemic time associated with transplant, but no significant volume changes were observed. Continued observation of outcomes and volume under the new allocation system will be necessary in the upcoming years.

An Attempt to Decompose the Impact of Land Use and Climate Change on Annual Runoff in a Small Agricultural Catchment

The aims of this study are: i) to better understand the coupled interactions between land use changes, climate change and the aquatic ecosystem in a small agricultural catchment (<100 km2) with a long observation history (1963–2018) and a known land use history, and ii) to test available approaches to separate land use and climate change impacts on water resources in such a small catchment. The pre- and post-change periods have been separated based on change points and the known land use history. Next, conceptual and analytical approaches were applied to quantify and to distinguish between the impacts of climate and land use changes on annual runoff for these two periods. Over the observation period, both land use changes (increase in forest areas) as well as climate change (a temperature rise and a decrease in annual precipitation) occurred. These changes contributed to a decrease in the average annual runoff by 51.9 mm (49% of the long-term average) during the observation period. The quantified contributions of climate and land use changes to the decrease in the mean annual runoff amount to between 60% and 80% and between 40% and 20%, respectively. (i) The results obtained from different methods were consistent - a change in runoff was primarily caused by shifts in climatic variables. (ii) However, the quantified contributions varied depending on the method applied and the form of the Budyko curve. (iii) Thus, special care should be taken in relation to the selection of the Budyko curve for quantifying these changes. (iv) Knowledge of the water deficit sources can result in better planning of water resources management in such small catchments.

HIV, HCV, and HBV incidence and residual risk in US blood donors before and after implementation of the 12-month deferral policy for men who have sex with men.

In December 2015, the men who have sex with men (MSM) deferral was reduced to 12 months in the United States. We compared human immunodeficiency virus (HIV), hepatitis C virus (HCV), and hepatitis B virus (HBV) incidence and residual risk before and after this policy change using data from >50% of the US blood supply. Three estimation intervals from the Transfusion-Transmissible Infections Monitoring System were compared: 15-months pre- and two consecutive, nonoverlapping 15-month post-MSM deferral implementation. Repeat, first-time, and weighted all-donor incidences were estimated. Residual risk was calculated for all incidence estimates using the incidence/window-period method. HIV repeat donor incidence was 1.57 per 100 000 person-years (phtpy) in the second 15-month post change and not significantly different from pre-MSM incidence of 2.19 phtpy. Similar values were seen for HCV (1.49 phtpy vs 1.46 phtpy) and HBV (1.14 phtpy vs 0.97 phtpy). In some cases, higher estimated incidence, but without significant change from pre-MSM to the second post change period occurred for males and first-time donors (eg, first-time donors, second post change period: 6.12 phtpy HIV, 6.41 phtpy HCV and 5.34 phtpy HBV). Estimated per donation residual risk was 1:1.6 million for HIV, 1:2.0 million for HCV and 1:1.0 million for HBV based on weighted incidence for all donors. Repeat, first-time, and overall donor incidence did not vary significantly comparing pre-MSM to either of the post-MSM estimation intervals. Residual risk estimates vary by study, but all yield residual risks in the United States of ≤1 per million, and thus far have not shown increasing risk with the 12-month MSM policy change.

Effect of general manager changes on financial performance: a study on BIST 30 companies

Purpose- The decisions of the top managers of a company significantly affect the financial performance of that company. For companies, the general manager is actually the most valuable intellectual resource for that company. General managers' influence on strategies and organizational outcomes is critical. In this respect, the study is important and focuses on whether changes in the general manager have an impact on financial performance. There are many criteria for the selection of a new general manager. In this election, almost like a "horse race", companies can finish this job by choosing from among the inside candidates or buy the experience from outside. Candidates selected from the inside can act faster and on the spot because they know the company. External candidates, on the other hand, can make more agile and correct decisions because they have a pool of resumes and different experiences. This study aims to analyze the financial performance of companies included in the BIST30 index. When the literature is searched, the decisions of the company’s top management and the status of the company, which are the main factors of this study, significantly affect the financial performance of the companies. The study is carried out to measure the financial performance impact based on the periods with a change of general manager. The focus and purpose of the study are to analyze the financial performance of the general manager change while analyzing whether the status of the company as a public/private company has an effect on financial performance. In this respect, the study is different from other studies. Methodology- The design of the research covers companies with a change of general manager. The main body of the research consists of public companies included in the Borsa Istanbul (BIST) 30 index. First of all, within the scope of the literature examined on the effect of general manager changes on financial performance, variables such as ROA, ROE, Tobin's Q are used as dependent variables and Leverage Ratio, Share Closing Price, General Manager Change, General Manager's Origin, General Manager's Experience and Number of Employees determined as. Data on firm performance indicators were obtained from the PDP (Public Disclosure Platform) electronic database, Thomson Reuters Eikon Data Terminal and independent audit reports of the companies. In order to measure the impacts better, data for the pre and post-change periods were also collected. In order to create a balanced panel set, 24 companies out of 30 companies included in the Borsa Istanbul (BIST) 30 index were included in the research. The reason why 6 companies are excluded from the scope of the analysis is that there are no general manager changes as of the quarter periods of 2011-2019, which were included in the scope of work in the relevant companies. The effects of the origins, experience, and status of the newly appointed general manager on the financial performance of the company as a public/private sector company were analyzed with panel data regression analysis. Descriptive statistics were created, panel unit root tests, Hausman test, and panel regression analysis were performed respectively in order to achieve the purpose of the study. Findings- This study conducted on Borsa Istanbul (BIST) 30 Companies was not consistent in terms of regression results. First of all, within the scope of the analysis, it has been concluded that there is no significant relationship between the general manager changes and the financial performance of the company. While examining this effect, the selection of the general manager, which is frequently mentioned in the literature, by the internal or the external appointment was included in the analysis, and as a result, it was determined that the newly appointed general manager was selected through internal appointment and external appointment did not have an effect on financial performance. As a result of the study, a similar result was reached with the study conducted by Fanegan (2010) in the literature. According to the findings obtained from the analysis, it was concluded that the effect of being a Public/Private Sector company within the scope of general manager changes on financial performance was not found to be statistically significant. This result stands out as a point that diverges from the literature. Conclusion- The effect of the changes in the general manager on the financial performance of the companies was found to be statistically insignificant for the 24 companies included in the BIST30 companies and the period 2011Q1-2019Q4.

Assessment of the impact of climate variability and human activities on the runoff in five catchments of the Adriatic Coast of south-central Italy

Study regionSouth-central Italy. Study focusA detailed analysis is carried out in five catchments in the Adriatic Coast where a complex system of artificial lakes, forced conducts and hydropower stations has modified the river regime. This together with the decrease of the annual rainfall in central Italy, make quantifying the relative contributions of human activities and climatic variability to streamflow change a challenging task. Statistically significant trends in annual rainfall and streamflow and change points in runoff have been investigated. Potential changes in precipitation-runoff relationship have been examined and a quantitative evaluation of the effect of climate variability and human activities on runoff has been assessed separately. New hydrological insights for the regionSignificant negative trends in runoff have been found in all the catchments, except the Feltrino river. Precipitation also exhibits negative trend, except the Pescara basin. Significant change points in runoff were detected in all the basins and the study period was divided in a pre-change and a post-change period. By climate elasticity method the climatic variability seems to be the main driving factor of the runoff decrease. Only for the Pescara river human activities were dominant factors of the runoff reduction, as expected from the absence of any significant trend in the annual precipitation. The hydrological model confirms this result, although the assessment of two contributions is affected by some uncertainties.

Distinguishing the multiple controls on the decreased sediment flux in the Jialing River basin of the Yangtze River, Southwestern China

Riverine sediment flux is a crucial proxy influencing channel morphology, biogeochemical processes, and riverine ecosystems. However, recent climate change and multiple anthropogenic activities have substantially altered the sediment regimes of the world’s rivers. On a basis of the “multiple double mass curves” method, this study selected the Jialing River (JR) basin as a case study to distinguish the relative impacts of climate change, land-use change, and damming on changes in the runoff and sediment flux over the past 60 years. The results showed that the sediment fluxes in the JR basin drastically decreased by 57–77% from the baseline period (1950s–1984) to the post-change period (1985–2017) mainly due to damming (60–75%), climate change (5–30%), and revegetation (10–20%). The runoff in the JR basin also exhibited a reduction (12–22%) likely because of the joint impacts of a reduction in precipitation and the restoration of vegetation. Although the 2008 Wenchuan Earthquake (M = 7.9) increased the short-term sediment fluxes, its impact on the long-term sediment fluxes in the downstream areas of the JR basin was limited as a result of the buffering effect of the thousands of constructed reservoirs. The decreased sediment fluxes in the JR basin benefit the life expectancy of the Three Gorges Reservoir (the world’s largest hydropower plant), but the reduced runoff can exacerbate water stress. The findings of our study have important implications for better management of water resources, sediment fluxes, and reservoir sedimentation not only for the JR basin, but also for the Three Gorges Reservoir.

Modeling hydro-climatic changes of evapotranspiration over a semi-arid river basin of India

Abstract Parametric models of actual evapotranspiration (AET) based on precipitation (P) and potential evapotranspiration (PET) are region-specific and purely climate-induced and limited to represent the hydrological water balances. Basin-averaged model parameters considering P, AET, and runoff (R) using a machine learning algorithm, ensemble regression model, is proposed. Hydrologically calibrated model parameters allowed the study of AET under alterations of water use for current and for future scenarios under climate change. The effect of climate, water, and land use changes on AET was studied for the post-change period of 2004–2014 compared to pre-change period of 1965–2003 over Krishna river basin (KRB), India. The AET has increased under climate and water use changes while there is both increase and decreases of AET under land use changes for post-change period compared to pre-change period over the basin. Severe water shortages were estimated under pronounced increase of temperature (1.29 °C) compared to precipitation increase (2.19%) based on Coordinated Regional Downscaling Experiment (CORDEX) projections for the period 2021–2060. Hydrologically induced AET changes were more pronounced than climate for current climate; whereas climate-induced AET changes were found to be more prominent for projected climate signals over the basin.

Evolution of streamflow patterns in Goulburn-Broken catchment during 1884–2018 and its implications for floodplain management

Abstract Development of water resources infrastructure largely decoupled floodplains and wetlands from rivers due to alteration of streamflow patterns. However, there is limited understanding of undesirable changes in streamflow patterns due to flow regulation. This study aimed to examine effects of flow regulation and rainfall variation on: 1) long-term flow, 2) upstream and downstream flow, and 3) seasonal flow patterns in the Goulburn-Broken catchment in Victoria, Australia, and discuss the implications for floodplains and wetlands. The non-parametric Mann-Kendall test and other statistical methods were used to analyse changes in long-term (1884–2018), upstream and downstream (1977–2018), and seasonal flow patterns of Goulburn River. Results showed that average annual discharge of Goulburn River decreased over 59% during the post-change period (1957–2018) as compared to pre-change (1884–1956) discharge mainly due to flow regulation and diversion (>86%). This reduced frequency of overbank flows from once every 1.6 years in the pre-change period to once every 5 years in the post-change period. This extended disconnection of floodplains from the Goulburn River has had detrimental effects on biota. Finally, generation of adequate overbank flows and maintaining natural variability of high and low flows with a riverine functional flow approach is recommended to rejuvenate floodplains and wetlands.

Assessing the effects of climate change and human activities on runoff variations from a seasonal perspective

Previous studies attempting to quantify the contributions of climate change and human activities to runoff variations in a changing environment have widely focused on an annual scale, while seasonal scales are rarely involved. China is the largest socialist country in the world, and its economic development is affected by its Five-year Plan policy. To this end, the upper Han River Basin, the largest tributary of the Yangtze River Basin, was selected as a case study. A seasonal-scale Budyko framework was extended based on the monthly abcd model in this study for quantifying the effects of climate and human activities changes on seasonal runoff variations, especially exploring the effect of China’s Five-year Plan policy. Results disclose that: (1) the change point in the annual runoff series is 1990, and the monthly abcd model achieves good performance in the prechange and postchange period; (2) the relative contribution of climate change to runoff variations is 62.99%, 70.20%, 87.54%, and 90.30% in spring, summer, autumn, and winter, respectively, indicating that climate change is the dominant factor controlling runoff variations in every season; (3) the contributions of climate change and human activities show obvious dynamic and seasonal characteristics, which are strongly impacted by the implementation of the Five-year Plan policy. Generally, the findings of this study provide valuable references for local reasonable water resource planning and management to make timely and appropriate use of the water supply.