Linking hydrological signatures to hydrological processes and catchment attributes: a flexible approach applied to baseflow signatures

Author(s):  
Sebastian Gnann ◽  
Nicholas Howden ◽  
Ross Woods ◽  
Hilary McMillan

<p>Hydrological signatures aim at extracting information about certain aspects of hydrological behaviour. They can be used to quantify hydrological similarity, to explore catchment functioning and to evaluate hydrological models. Relating hydrological signatures to hydrological processes is, however, still a challenge and many signatures remain poorly understood.</p><p>We propose a flexible approach for linking hydrological signatures to hydrological processes, which might help to improve our understanding and hence the usefulness of certain hydrological signatures. As a first step, we should build a perceptual model describing the hydrological process of interest. We should then try to find or create relevant – and ideally widely available – catchment attributes that target the process of interest, and hence have the potential to explain the signature in a process-based way. We should control for climate by either incorporating it into our perceptual model or by analysing sub-climates individually, to disentangle the influences of forcing and catchment form. Lastly, simple conceptual models might be a useful tool to systematically explore the controlling factors (parameters, forcing) of a signature. Focusing on hydrological processes and explaining hydrological signatures in a process-based way will make hydrological signatures more meaningful, useful and robust.</p><p>The proposed approach is tested on signatures related to baseflow and groundwater processes, such as the baseflow index. Baseflow generation has been studied extensively, and while many regional studies could identify landscape controls on baseflow generation (e.g. soils and geology), continental or global studies have resulted in a less clear picture, partially because of the masking influence of climate at these scales. Furthermore, the relationship between controls, such as climate and catchment form, and baseflow response has often been only described statistically (e.g. by means of regression-type approaches).  A mechanistic theory based on widely available catchment attributes (e.g. soils, geology, topography) would thus be a major step towards improved understanding and transferability.</p>

2015 ◽  
Vol 19 (10) ◽  
pp. 4365-4376 ◽  
Author(s):  
M. Pfannerstill ◽  
B. Guse ◽  
D. Reusser ◽  
N. Fohrer

Abstract. To ensure reliable results of hydrological models, it is essential that the models reproduce the hydrological process dynamics adequately. Information about simulated process dynamics is provided by looking at the temporal sensitivities of the corresponding model parameters. For this, the temporal dynamics of parameter sensitivity are analysed to identify the simulated hydrological processes. Based on these analyses it can be verified if the simulated hydrological processes match the observed processes of the real world. We present a framework that makes use of processes observed in a study catchment to verify simulated hydrological processes. Temporal dynamics of parameter sensitivity of a hydrological model are interpreted to simulated hydrological processes and compared with observed hydrological processes of the study catchment. The results of the analysis show the appropriate simulation of all relevant hydrological processes in relation to processes observed in the catchment. Thus, we conclude that temporal dynamics of parameter sensitivity are helpful for verifying simulated processes of hydrological models.


1960 ◽  
Vol 20 (4) ◽  
pp. 588-596 ◽  
Author(s):  
Henry W. Broude

The purpose of this paper is to serve as a point of departure for discussion of the relationship of regional differentiation and growth to general economic development. In addition to touching on methodological problems, I hope to establish two specific points: (a) that the needs of economic history call for particular perspectives in delimiting regions, and (b) that study of regional interaction can provide insights in an understanding of national economic development.


2005 ◽  
Vol 37 (3) ◽  
pp. 753-775
Author(s):  
Pitman B. Potter ◽  
Li Jianyong

This paper examines the new Labour Law of the PRC, effective January 1, 1995, in the light of current and historical conditions of labour relations in China. Provisions regarding the labour contract system and dispute resolution are discussed in greater detail. Issues related to the introduction of collective bargaining and to the relationship between trade unions and the Communist Party are also examined. In their overall assessment, the authors recognize the potential significance of the Labour Law as a major step towards the legal protection of workers' rights, but point out that its effectiveness could be undermined by the preeminent policy of economic growth, by concerns about political control, and by obstacles to full implementation.


2020 ◽  
Author(s):  
Emixi Valdez ◽  
Francois Anctil ◽  
Maria-Helena Ramos

<p>Skillful hydrological forecasts are essential for decision-making in many areas such as preparedness against natural disasters, water resources management, and hydropower operations. Despite the great technological advances, obtaining skillful predictions from a forecasting system, under a range of conditions and geographic locations, remain a difficult task. It is still unclear why some systems perform better than others at different temporal and spatial scales. Much work has been devoted to investigate the quality of forecasts and the relative contributions of meteorological forcing, catchment’s initial conditions, and hydrological model structure in a streamflow forecasting system. These sources of uncertainty are rarely considered fully and simultaneously in operational systems, and there are still gaps in understanding their relationship with the dominant processes and mechanisms that operate in a given river basin. In this study, we use a multi-model hydrological ensemble prediction system (H-EPS) named HOOPLA (HydrOlOgical Prediction Laboratory), which allows to account separately for these three main sources of uncertainty in hydrological ensemble forecasting. Through the use of EnKF data assimilation, of 20 lumped hydrological models, and of the 50-member ECMWF medium-range weather forecasts, we explore the relationship between the skill of ensemble predictions and the many descriptors (e.g. catchment surface, climatology, morphology, flow threshold and hydrological regime) that influence hydrological predictability. We analyze streamflow forecasts at 50 stations spread across Quebec, France and Colombia, over the period from 2011 to 2015 and for lead times up to 9 days. The forecast performance is assessed using common metrics for forecast quality verification, such as CRPS, Brier skill score, and reliability diagrams. Skill scores are computed using a probabilistic climatology benchmark, which was generated with the hydrological models forced by resampled historical meteorological data. Our results contribute to relevant literature on the topic and bring additional insight into the role of each descriptor in the skill of a hydrometeorological ensemble forecasting chain, serving as a possible guide for potential users to identify the circumstances or conditions in which it is more efficient to implement a given system.</p><p> </p>


2020 ◽  
Author(s):  
Li Wang ◽  
Fan Zhang

<p>The glacier ratio influences both the contribution of meltwater runoff and the response of the basin's hydrological processes to climate change. In this study, the Karuxung, the Tuotuo and the Babao river basins with glaciers accounting for 20.7%, 2.1% and 0.38% respectively, were selected to study their hydrological processes under the climate change. Based on the daily runoff data of 30 years and MODIS snow cover products, the J2000 model was applied to quantify the contribution of meltwater and rainfall runoff, analyze the temporal and spatial variation characteristics of runoff and clarify the influence of climate change on these three basin. The main findings are as follows: (1) The contribution of glacier and snow melt runoff for the Karuxung, Tuotuo and Babao river basin was 60.7%, 25.3% and 19.9%, respectively. The contribution of rainfall runoff for the three basins was 39.3%, 74.7% and 81.1%, respectively. (2) The peak of glacier and snow melt runoff converted from summer to spring with the glacier ratio decreasing. (3) The runoff supplies in the Karuxung, Tuotuo and Babao river basin were from the 5500m-6500m, 4500m-5500m zone, and 3500m-4500m elevation zone, respectively. (4) The runoff and its components in the Karuxung and Tuotuo river basins showed significant increasing trends while the Babao river basin showed no significant change trends. (5) In the Karuxung river basin with large glacier ratio, the increase in temperature mainly caused the increase of meltwater and runoff, showing a positive impact on runoff. For the Tuotuo and Babao river basin with small glacier ratios, the increase in temperature mainly caused increased evaporation and reduced runoff, showing a negative impact on runoff.</p>


2021 ◽  
Vol 21 (3) ◽  
pp. 961-976
Author(s):  
Gijs van Kempen ◽  
Karin van der Wiel ◽  
Lieke Anna Melsen

Abstract. Hydrological extremes affect societies and ecosystems around the world in many ways, stressing the need to make reliable predictions using hydrological models. However, several different hydrological models can be selected to simulate extreme events. A difference in hydrological model structure results in a spread in the simulation of extreme runoff events. We investigated the impact of different model structures on the magnitude and timing of simulated extreme high- and low-flow events by combining two state-of-the-art approaches: a modular modelling framework (FUSE) and large ensemble meteorological simulations. This combination of methods created the opportunity to isolate the impact of specific hydrological process formulations at long return periods without relying on statistical models. We showed that the impact of hydrological model structure was larger for the simulation of low-flow compared to high-flow events and varied between the four evaluated climate zones. In cold and temperate climate zones, the magnitude and timing of extreme runoff events were significantly affected by different parameter sets and hydrological process formulations, such as evaporation. In the arid and tropical climate zones, the impact of hydrological model structures on extreme runoff events was smaller. This novel combination of approaches provided insights into the importance of specific hydrological process formulations in different climate zones, which can support adequate model selection for the simulation of extreme runoff events.


Author(s):  
Alberto Acosta ◽  
Ana M. González

There are few regional studies attempting to compare the asexual reproductive output of marine populations, particularly when they are exposed to different environmental conditions. In this study we compared Caribbean and Southwestern Atlantic Palythoa caribaeorum populations in terms of ramet production, the minimum colony size for fission, and the relationship between fission frequency and colony size. Fission process was quantified in Ponta Recife and Praia Portinho, Sao Paulo, Brazil, and in Punta de Betín, Colombia, during the summer (December-January) of 1997 and 1998, respectively. Fission started at small colony size in both populations studied (> 4 cm2). The number of ramets produced per colony increased with colony size in Brazil and Colombia. Colombian zoanthids produced more ramets by fission than Brazilian populations. The populations shared early reproduction characteristics, and production of large numbers of ramets, which increased with colony size, even though they differed in fission frequency. Fission seems to be a conservative trait in P. caribaeorum, although its expression could vary depending on habitat conditions related to biotic and / or abiotic factors.


Author(s):  
Son Ngo ◽  
Huong Hoang ◽  
Phuong Tran ◽  
Loc Nguyen

Land use/land cover (LULC) and climate changes are two main factors directly affecting hydrologic conditions. However, very few studies in Vietnam have investigated changes in hydrological process under the impact of climate and land use changes on a basin scale. The objective of this study is to assess the individual and combined impacts of land use and climate changes on hydrological processes for the Nam Rom river basin, Northwestern Viet Nam using Remote Sensing (RS) and Soil and Water Assessment Tools (SWAT) model. SWAT model was used for hydrological process simulation. Results indicated that SWAT proved to be a powerful tool in simulating the impacts of land use and climate change on catchment hydrology. The change in historical land use between 1992 and 2015 strongly contributed to increasing hydrological processes (ET, percolation, ground water, and water yield), whereas, climate change led to significant decrease of all hydrological components. The combination of land use and climate changes significantly reduced surface runoff (-16.9%), ground water (-5.7%), water yield (-9.2%), and sediment load (-4.9%). Overall climatic changes had more significant effect on hydrological components than land use changes in the Nam Rom river basin during the 1992–2015. Under impacts of projected land use and climate change scenarios in 2030 on hydrological process of the upper Nam Rom river basin indicate that ET and surface flow are more sensitive to the changes in land use and climate in the future. In conclusion, the findings of this study will basic knowledge of the effects of climate and land-use changes on the hydrology for future development of integrated land use and water management practices in Nam Rom river basin.


Water ◽  
2020 ◽  
Vol 12 (8) ◽  
pp. 2227
Author(s):  
Polona Vreča ◽  
Zoltán Kern

Stable (16O, 17O, 18O, 1H, 2H) and radioactive (3H) isotopes in water are powerful tools in the tracking of the path of water molecules in the whole water cycle. In the last decade, a considerable number of studies have been published on the use of water isotopes, and the number continues to grow due to the development of new measurement techniques (i.e., laser absorption spectroscopy) that allow measurements of stable isotope ratios at ever-higher resolutions. Therefore, this Special Issue (SI) has been compiled to address current state-of-the-art water isotope methods, applications, and hydrological process interpretations and to contribute to the rapidly growing repository of isotope data important for future water resource management. We are pleased to present here a compilation of 14 papers reporting the use of water isotopes in the study of hydrological processes worldwide, including studies on the local and regional scales related either to precipitation dynamics or to different applications of water isotopes in combination with other hydrochemical parameters in investigations of surface water, snowmelt, soil water, groundwater, and xylem water to identify the hydrological and geochemical processes.


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