Characteristics and causal factors of hysteresis in the hydrodynamics of a large floodplain system: Poyang Lake (China)

© 2017 Elsevier. This manuscript version is made available under the CC-BY-NC-ND 4.0 license http://creativecommons.org/licenses/by-nc-nd/4.0/ This author accepted manuscript is made available following 24 month embargo from date of publication (Aug 2017) in accordance with the publisher’s archiving policyA previous modeling study of the lake-floodplain system of Poyang Lake (China) revealed complex hysteretic relationships between stage, storage volume and surface area. However, only hypothetical causal factors were presented, and the reasons for the occurrence of both clockwise and counterclockwise hysteretic functions were unclear. The current study aims to address this by exploring further Poyang Lake’s hysteretic behavior, including consideration of stage-flow relationships. Remotely sensed imagery is used to validate the water surface areas produced by hydrodynamic modeling. Stage-area relationships obtained using the two methods are in strong agreement. The new results reveal a three-phase hydrological regime in stage-flow relationships, which assists in developing improved physical interpretation of hysteretic stage-area relationships for the lake-floodplain system. For stage-area relationships, clockwise hysteresis is the result of classic floodplain hysteretic processes (e.g., restricted drainage of the floodplain during recession), whereas counterclockwise hysteresis derives from the river hysteresis effect (i.e., caused by backwater effects). The river hysteresis effect is enhanced by the time lag between the peaks of catchment inflow and Yangtze discharge (i.e., the so-called Yangtze River blocking effect). The time lag also leads to clockwise hysteresis in the relationship between Yangtze River discharge and lake stage. Thus, factors leading to hysteresis in other rivers, lakes and floodplains act in combination within Poyang Lake to create spatial variability in hydrological hysteresis. These effects dominate at different times, in different parts of the lake, and during different phases of the lake’s water level fluctuations, creating the unique hysteretic hydrological behavior of Poyang Lake

Organic matter cycling in a restored wetland receiving complex effluent

Wetlands are used to treat anthropogenic effluents due to their capacity for intense biogeochemical processing of nutrients and other pollutants, yet their role in processing effluent dissolved organic matter (DOM) is unclear. Here, I quantified the cycling of DOM in Frank Lake, an economically-important wetland restored using multiple effluent sources. Optical analyses and microbial incubations showed DOM changed from protein-like and bioavailable at the effluent inflow site to more aromatic and less bioavailable at the outflow, due to the processing and replacement of effluent DOM with that from marsh plants and wetland soils. My mass balance showed Frank Lake was a net long-term source of DOM, but shifted from a source to sink among wet and drought periods that respectively shortened or lengthened the water residence and DOM processing times. Overall, Frank Lake appears to effectively process effluent DOM, despite being a longer-term source of DOM to downstream environments

Scientific Evidence from Space - A Review of Spaceborne Remote Sensing Applications at the Science-Policy Interface

On a daily basis, political decisions are made, often with their full extent of impact being unclear. Not seldom, the decisions and policy measures implemented result in direct or indirect unintended negative impacts, such as on the natural environment, which can vary in time, space, nature, and severity. To achieve a more sustainable world with equitable societies requires fundamental rethinking of our policymaking. It calls for informed decision making and a monitoring of political impact for which evidence-based knowledge is necessary. The most powerful tool to derive objective and systematic spatial information and, thus, add to transparent decisions is remote sensing (RS). This review analyses how spaceborne RS is used by the scientific community to provide evidence for the policymaking process. We reviewed 194 scientific publications from 2015 to 2020 and analysed them based on general insights (e.g., study area) and RS application-related information (e.g., RS data and products). Further, we classified the studies according to their degree of science–policy integration by determining their engagement with the political field and their potential contribution towards four stages of the policy cycle: problem identification/knowledge building, policy formulation, policy implementation, and policy monitoring and evaluation. Except for four studies, we found that studies had not directly involved or informed the policy field or policymaking process. Most studies contributed to the stage problem identification/knowledge building, followed by ex post policy impact assessment. To strengthen the use of RS for policy-relevant studies, the concept of the policy cycle is used to showcase opportunities of RS application for the policymaking process. Topics gaining importance and future requirements of RS at the science–policy interface are identified. If tackled, RS can be a powerful complement to provide policy-relevant evidence to shed light on the impact of political decisions and thus help promote sustainable development from the core

Investigating summer thermal stratification in Lake Ontario

Summer thermal stratification in Lake Ontario is simulated using the 3D hydrodynamic model Environmental Fluid Dynamics Code (EFDC). Summer temperature differences establish strong vertical density gradients (thermocline) between the epilimnion and hypolimnion. Capturing the stratification and thermocline formation has been a challenge in modeling Great Lakes. Deviating from EFDC's original Mellor-Yamada (1982) vertical mixing scheme, we have implemented an unidimensional vertical model that uses different eddy diffusivity formulations above and below the thermocline (Vincon-Leite, 1991; Vincon-Leite et al., 2014). The model is forced with the hourly meteorological data from weather stations around the lake, flow data for Niagara and St. Lawrence rivers; and lake bathymetry is interpolated on a 2-km grid. The model has 20 vertical layers following sigma vertical coordinates. Sensitivity of the model to vertical layers' spacing is thoroughly investigated. The model has been calibrated for appropriate solar radiation coefficients and horizontal mixing coefficients. Overall the new implemented diffusivity algorithm shows some successes in capturing the thermal stratification with RMSE values between 2-3°C. Calibration of vertical mixing coefficients is under investigation to capture the improved thermal stratification

Schistosomiasis control in China : strategy of control and rapid assessment of schistosomiasis risk by remote sensing (RS)and geographic information system (GIS)

Human schistosomiasis remains one of the most prevalent parasitic infections in the tropics and subtropics. The disease currently is endemic in 76 countries and territories and continues to be a major public health concern, especially in the developing world. It is estimated that 650 million people are at risk of infection. Among the 200 million people actually infected, 120 million are symptomatic and 20 million suffer severe disease. Although morbidity control – in line with recommendations put forth by the World Health Organization – has been carried out in China for more than 20 years, it is estimated that 90 million people still live in areas where they are at risk of infection, and 820,000 people are infected with the parasite, i.e. Schistosoma japonicum. The estimated area of intermediate host snail habitats comprise 3,436 km2, concentrated in the 5 lake regions along the Yangtze River that include the provinces of Anhui, Jiangsu, Jiangxi, Hubei and Hunan. The marshlands of the Poyang Lake region represent some of the strongholds for the transmission of S. japonicum. In these settings, for example, the percentages of acute cases and intermediate host snail habitats represent 79.5% and 96.4%, respectively. With the World Bank Loan Project (WBLP) to control schistosomiasis in China, the overall prevalence of S. japonicum was significantly reduced, but in highly endemic areas the re-infection rates are high. In the first part of the present thesis, I summarize the 50-year history of China’s experience and expertise in schistosomiasis control. Particular emphasis is placed on morbidity control and achievements made by the WBLP carried out between 1992 and 2001. Reviewing this body of literature reveals that morbidity control of schistosomiasis in China has been successful, and hence this strategy will continue to form the backbone of protecting people’s health. However, total expenditures have been considerable, and with the termination of the WBLP there is concern that schistosomiasis might re-emerge. In the second part of this thesis, I describe the successful development of a novel compound model to identify the habitats of Oncomelania hupensis, the intermediate host snail of S. japonicum, and hence the identification of high-risk areas of disease transmission. There are three findings that warrant particular notion. First, visual land use classification on multi-temporal Landsat images was performed for preliminary prediction of O. hupensis habitats. Second, extraction of the normalized difference vegetation index and the tasseled cap transformation greenness index were used for improved snail habitat prediction. Third, buffer zones with distances of 600 and 1,200 m were made around the predicted snail habitats to differentiate between high (>15%), moderate (3-15%) and low risk of S. japonicum infection prevalence (< 3%). Preliminary validation of the compound model against ground-based snail surveys in the Poyang Lake region revealed that the model had an excellent predictive ability. The model therefore holds promise for rapid and inexpensive identification of high-risk areas, and can guide subsequent control interventions, such as whether mass or selective chemotherapy should be employed. The model can also be used for diseases surveillance in general and the monitoring of ecological transformations on the transmission dynamics of S. japonicum, for example in the Three Gorges Dam area

Potential impact of climate change and water resources development on the epidemiology of schistosomiasis in China

Schistosomiasis japonica, caused by the blood fluke Schistosoma japonicum, has been endemic in China since ancient times. An estimated 11 million people were infected in the mid-1950s. Recognizing the huge public health significance and the economic impact of the disease, the central government of China implemented a large-scale control programme, which has been sustained and constantly adapted over the past half century. Today, the endemic areas are mainly confined to the lake and marshland regions along the Yangtze River in five provinces, namely Jiangsu, Anhui, Jiangxi, Hunan and Hubei. It is estimated that currently about 800,000 people are infected and that 40 million people are at risk of infection. Historically, the northern geographical limit where schistosomiasis transmission occurred was around the 33°15’ N latitude (e.g. in Baoying county, Jiangsu province), governed by low temperature thresholds. Based on various climate models, the Intergovernmental Panel of Climate Change (IPCC) recently concluded that the Earth has warmed by approximately 0.6°C over the past 100 years. This unusual warming has been particularly pronounced during the last three decades. There is growing consensus that the global trend of climate warming will continue in the 21st century. It has been suggested that climate change could impact on the distribution of the intermediate host snail of S. japonicum, i.e. Oncomelania hupensis. The frequency and transmission dynamics of schistosomiasis can also be affected by waterresource development and management. Among others, the South-to-North Water Transfer (SNWT) project” is currently under construction in China, which intends to divert water from South (the snail-infested Yangtze River) to North (Beijing and Tianjing) via the lakes of Gaoyou, Hongze and others. The implementation and operation of this project could further amplify the negative effects of climate change and facilitate the northward spread of O. hupensis. The main objective of this PhD thesis was to explore the potential impact of climate change and the SNWT project on the future distribution of schistosomiasis japonica, particularly in eastern China. The techniques used were geographic information system (GIS) and remote sensing (RS), coupled with Bayesian spatial statistics, which have become key tools for disease mapping and prediction. First, we reviewed the application of GIS/RS techniques for the epidemiology and control of schistosomiasis in China. The applications included mapping prevalence and intensity data of S. japonicum at a large scale, and identifying and predicting suitable habitats for O. hupensis at a small scale. Other prominent applications were the prediction of infection risk due to ecological transformations, particularly those induced by floods and water-resource development projects, and the potential impact of climate change. We discussed the limitations of the previous work, and outlined potential new applications of GIS/RS techniques, namely quantitative GIS, WebGIS and the utilization of emerging satellite-derived data, as they hold promise to further enhance infection risk mapping and disease prediction. We also stressed current research needs to overcome some of the remaining challenges of GIS/RS applications for schistosomiasis, so that further and sustained progress can be made towards the ultimate goal to eliminate the disease from China. Second, recognizing the advantages of combining GIS/RS techniques with advanced spatial statistical approaches, we developed Bayesian spatio-temporal models to analyze the relationship between key climatic factors and the risk of schistosomiasis infection. We used parasitological data collected annually from 1990 to 1998 by means of cross-sectional surveys carried out in 47 counties of Jiangsu province. Climatic factors, namely land surface temperature (LST) and normalized difference vegetation index (NDVI), were obtained from satellite sensors. Our analysis suggested a negative association between NDVI and the risk of S. japonicum infection, whereas an increase in LST contributed to a significant increase in S. japonicum infection prevalence. Third, in order to better understand the changes in the frequency and transmission dynamics of schistosomiasis in a warmer future China, a series of laboratory experiments were conducted to assess the effect of temperature on the parasite-intermediate host snail interaction. We found a positive linear relationship between the development of. S. japonicum larvae harboured in O. hupensis and temperature. In snails kept at 15.3°C, S. japonicum larvae tend to halt their development, while peak development occurs at 30°C. The temperature at which half of the snails were in hibernation is 6.4°C. A statistically significant positive association was observed between temperature and oxygen intake of O. hupensis at temperatures below 13.0°C. We also detected a logistic relationship between snails’ oxygen intake and their hibernation rate. Our results underscored the important role temperature plays both for the activity of O. hupensis and the development of S. japonicum larvae harboured in the intermediate host snail. Fourth, to substantiate the claim that global warming might alter the frequency and transmission dynamics of S. japonicum in China, we conducted a time-series analysis from 1972-2002, using temperature data from 39 counties of Jiangsu province. Using annual growing degree days (AGDDs) with a temperature threshold of 15.3°C, we forecasted changes in S. japonicum transmission. The final model included a temporal and a spatial component. The temporal trend consisted of second order polynomials in time plus a seasonality component, while the spatial trend was formed by second order polynomials of the coordinates plus the thin plate smoothing splines. The AGDDs of S. japonicum in 2003 and 2006 and their difference were calculated. The temperatures at the 39 locations showed an increasing temporal trend and seasonality with periodicities of 12, 6 and 3 months. The predicted AGDDs increased gradually from north to south in both 2003 and 2006. The increase in AGDD was particularly pronounced in the southern part of the study area. Our results suggest that alterations in the transmission intensity of S. japonicum in south Jiangsu will be more pronounced than in the northern part of the province. Fifth, we further assessed the potential impact of climate change on the distribution of O.hupensis via a spatially-explicit analytical approach. We employed two 30-year composite datasets comprising average monthly temperatures collected at 623 meteorological stations throughout China, spanning the periods 1961-1990 and 1971-2000. Temperature changes were assessed spatially between the 1960s and the 1990s for January, as this is the critical month for survival of O. hupensis. Our results show that the mean January temperatures increased at 590 stations (94.7%), and that China’s average January temperature in the 1990s was 0.96°C higher than 30 years earlier. The historical 0-1°C January isotherm, which has been considered the approximate northern limit of S. japonicum transmission, has shifted from 33°15’ N to 33°41’ N, expanding the potential transmission area by 41,335 km2. This translates to an estimated additional 21 million people at risk of schistosomiasis. Two lakes that form part of the SNWT project are located in this new potential transmission area, namely Hongze and Baima. Finally, we applied GIS/RS techniques to predict potentially new snail habitats around the lakes of Hongze and Baima, as well as Gaoyou lake, which is considered as a habitat where O. hupensis could re-emerge. A model based on flooding areas, NDVI and a wetness index extracted from Landsat images was developed to predict the snail habitats at a small scale. A total of 163.6 km2 of potential O. hupensis habitats were predicted around the three study lakes. In conclusion, our work suggests that global warming and a major water-resource development project could impact on the distribution of S. japonicum and its intermediate host snail in China and demonstrates that the combination of GIS, RS and Bayesian spatial statistical methods is a powerful approach in estimating their extent. The predictions can serve as a basis for health policy makers and disease control managers, and can be of use in the establishment and running of schistosomiasis surveillance systems. It is further suggested that an efficient early warning system should be set up in potential new endemic areas to monitor subtle changes in snail habitats due to climate change and major ecological transformations, and to assure the early detection of emerging and re-emerging schistosomiasis

Contingent valuation of Yangtze finless porpoises in Poyang Lake, China

Yangtze finless porpoises (YFPs) are the only fresh-water adapted porpoises in the world and they are endemic to Yangtze River system, including Poyang Lake. They are threatened by many factors, such as illegal fishing and overfishing, sand dredging, intensive shipping traffic, and pollution from agriculture and industry. Consequently, their population is decreasing at a great rate and they are listed as an endangered rare species on the red list of the International Union for Conservation of Nature (IUCN) since 1996. Moreover, a hydroelectricity project in Poyang Lake is in planning by the state of Jiangxi province, which will generate further serious threats to YFPs by cutting off their migration route and fragmenting their habitat. Therefore, it is very urgent to take some protection measures for YFPs. A special nature reserve is one possibility to protect YFPs, such as a nature reserve area, which is located in Poyang Lake. In order to find out whether a nature reserve is worthwhile, an economic analysis valuing the benefit of YFPs has been conducted. An appropriate method, the contingent valuation approach, has been chosen. The overall aim of such a contingent valuation study is to estimate the total benefits of YFPs by asking individuals’ willingness to pay for the porpoise conservation project. Because many people are unfamiliar with YFPs and the species’ total values consist of mainly non-use values, preference construction and estimating a demand function is a complex task. Therefore, the valuation workshop method, a group-based approach, which can make respondents motivated and well-informed so that they thoroughly consider the questions, provides a realistic decision-making environment. This method was selected to help respondents construct their preference. Within this study, a series of such valuation workshops were successfully organized and data and information were collected. The findings of the study have both methodological and policy-related implications. From the perspective of methodology, the important findings include: 1) Valid response rates are high enough to support further analysis and large mean WTP for porpoise conservation are obtained. Therefore, it can be concluded that the valuation workshop method as has been chosen in this study, is suitable for valuing porpoise conservation. The valuation workshop method can make people well informed about environmental goods and services, such as rare species, so that they can build their preference about them, which is quite a complex task for many individuals. IV 2) Distance effects are verified to fail to work on willingness to pay (WTP) for porpoise conservation, which is mostly driven by non-use values. Therefore, distance need not be included in the aggregation analysis of total benefits of YFPs. Similarly, the market for conservation of YFPs can be defined as the nation of China. And the sampling frame of such an evaluation of a rare species can be all the Chinese population. 3) Income effects are confirmed to be significantly influential for both Chinese respondents and German respondents. Hence, the aggregation of total values of YFPs should consider about individuals’ income levels and their ability to pay (ATP). It is inferred from the fact of smaller mean WTP in China as compared with Germany that some low-income respondents’ WTP bids are possibly distorted by their ATP, which needs further confirmation in follow-up research. In addition, there are also some policy-related implications, which are closely related with the mentioned methodological aspect: The total economic values of porpoise conservation are predicted to be appreciably huge. Definitely, their total benefits should be taken into account by politicians and decision-makers. This study makes explicit people’s attitudes and preference on the trade-off between economic growth and ecological use. The establishment of a special nature reserve for YFPs is still an open question

Ninth annual V.M. Goldschmidt Conference : August 22-27, 1999, Harvard University, Cambridge, Massachusetts

The meeting is a forum for presenting and discussing new chemical and isotopic measurements, experimental and theoretical results, and discoveries in geochemistry and cosmochemistry.sponsored by Geochemical Society ... [and others]hosted by Department of Earth and Planetary Sciences, Harvard University ; compiled by Lunar and Planetary Institute.PARTIAL CONTENTS: Bacteria-promoted Dissolution of a Common Soil Silicate / S.L. Brantley, L.I. Liermann, and B.E. Kalinowski--Evolution of Temperature Control on Alkenone Biosynthesis / S.C. Brassell--Chemical Composition of Silurian Seawater: Preliminary Results from Environmental Scanning Electron Microscopy-Energy Dispersive Spectroscopy Analyses of Fluid Inclusions in Marine Halites / S.T. Brennan, T. Lowenstein, M.N. Timofeeff, and L.A. Hardi