scholarly journals Hydrological System Complexity Induces a Drought Frequency Paradox

2021 ◽  
Vol 3 ◽  
Author(s):  
Joost Buitink ◽  
Theresa C. van Hateren ◽  
Adriaan J. Teuling

Droughts occur as a result of a lack of water compared with normal conditions. Whilst this appears trivial, the exact drought definition of drought is not. Especially as different drought types are present, resulting from the different variables in a hydrological system, each with unique characteristics. We use a common drought definition, the percentile score, and apply the same definition across all drought types, to study whether the actual occurrence of droughts matches the definition. We focus on the data-rich Dutch province of Gelderland, to study droughts from observations across five major components of the terrestrial hydrological cycle. When a percentile threshold of 20% is used as drought definition, corresponding to a mild drought, droughts anywhere in the system occur at least three times more frequently (73% of the time). On the other hand, the situation where drought occurs across all components of the terrestrial hydrological cycle is more than four times less likely than the drought threshold of 20% (namely 5% of the time). This can be attributed by both (1) the different responses across the hydrological system, and (2) the spatial variability present within each component of the hydrological system. With this study, we show the existence of the drought frequently paradox: although droughts are seen and defined as rare from a scientific perspective, when viewed from a societal or operational water management perspective in typical hydrological systems subject to spatial variability and other system complexity, droughts become common, rather than rare. This paradox is a consequence of an inconsistent use of the percentile score drought definition between research and operational water management, and better communication between the two domains is needed in search for a universally accepted drought definition.

2020 ◽  
Author(s):  
Yangzi Qiu ◽  
Igor da Silva Rocha Paz ◽  
Feihu Chen ◽  
Pierre-Antoine Versini ◽  
Daniel Schertzer ◽  
...  

Abstract. During the last decades, the urban hydrological cycle has been strongly modified by the built environment, resulting in fast runoff and increasing the risk of waterlogging. Nature-Based Solutions (NBS), which apply green infrastructures, have been more and more widely considered as a sustainable approach for urban stormwater management. However, the assessment of NBS performance still requires further modelling development because of their hydrological responses sensitively depends on the representation of multiscale space variability of both the rainfall and the NBS distribution. Indeed, we initially argue this issue with the help of the multifractal intersection theorem. To illustrate the importance of this question, the spatial heterogeneous distributions of two series of NBS scenarios (porous pavement, rain garden, green roof, and combined) are quantified with the help of their fractal dimension. We point out consequences of their estimates. Then, a fully-distributed and physically-based hydrological model (Multi-Hydro) was applied to consider the studied catchment and these NBS scenarios with a spatial resolution of 10 m under two different types of rainfall: distributed and uniform, and for three rainfall events. These simulations show that the impact of spatial variability of rainfall on the uncertainty of peak flow of NBS scenarios ranges from about 8 % to 17 %, which is more pronounced than those of the total runoff volume. In addition, the spatial variability of the rainfall intensity at the largest rainfall peak responds almost linearly to the uncertainty of the peak flow of NBS scenarios. However, the hydrological responses of NBS scenarios are less affected by the spatial distribution of NBS. Finally, the intersection effects of the spatial variability of rainfall and the spatial arrangement of NBS seem more pronounced for the peak flow of green roof scenarios and the total runoff volume of combined scenarios.


Author(s):  
F.-O. Tapia-Silva ◽  
A.-I. Contreras-Silva ◽  
E.-R. Rosales-Arriaga

The Usumacinta basin is characterized by aboundance of natural and scenic resources. It also houses a vast biodiversity (wich also means invaluable genetic resources). Its river is the longest in Mexico (main channel length of 927 km). Therefore it is one of the most productive regions of the country in terms of ecosystem services (such as habitat for biodiversity, maintenance of wetlands, water flows generation, carbon sequestration, soil retention, etc.) that are directly related to the hydrological functioning. During the last centuries, human activities on the Usumacinta basin have drastically changed its geomorphology and vegetation cover. As a result the hydrological cycle has been greatly modified. Therefore, it is necessary to conduct studies in order to support planning activities and implementation of public policies, as well as, to generate a permanent scientific ecosystem monitoring system. <br><br> This paper presents the results of a study focused on estimating the water balance of this frontier basin. Satellite and field data is used. Variables as vegetation cover (generated by classification of Landsat and MODIS), digital terrain model (SRTM), surface temperature (MODIS), potential evaporation, precipitation and runoff measurements were processed. Various techniques of Remote Sensing, geospatial models (as SSEB and the model for definition of surface hydrological connectivity) and spatial analysis (geostatistics and map algebra) were implemented. The results were integrated into the environment of a Geographic Information System. These are estimates of actual evapotranspiration, soil moisture and runoff, among other biophysical parameters. For the lower part of the basin a balance was performed to estimate inputs of water from runoff and precipitation to the large amount of wetlands in the area. Additionally, areas generating runoff and areas in which most of the precipitaion infiltrates were also mapped. The geo-information obtained is requiered for purposes of planning and land management.


2021 ◽  
Author(s):  
Yannick Back ◽  
Fabian Funke ◽  
Peter Marcus Bach ◽  
Joao Paulo Leitao ◽  
Wolfgang Rauch ◽  
...  

&lt;p&gt;In the face of rapid urban and population growth and with climate change altering precipitation patterns, urban water management is becoming increasingly demanding. Numerous software, tools and approaches to study urban water flow behaviour and model hydrological processes exist. However, the understanding of water movement in urban areas, especially during extreme events, and the physical principles behind them, as well as the interaction between the natural and the urban hydrological cycle is still incomplete. For decades, models suited for urban hydrological analysis greatly impacted the improvement of flood protection, public health and environmental protection, changing the way we look at urban water and stormwater management. In order to calculate accurate quantities of runoff in any rainfall/runoff model, information about urban sub-catchment characteristics plays an important role. Size, shape, topography, as well as land use influencing infiltration rates and evapotranspiration, are of great importance to calculate accurate runoff quantities on the urban scale. New implementations to reduce runoff towards the sewer system, such as decentralised stormwater techniques, increase the urgent need for accurate and high-resolution local/neighbourhood-scale information. Spatial and temporal developments require water management models to be connected with GIS (Geographical Information Systems). Initially not being developed to interact with each other, multiple approaches exist to combine GIS with water management models. Nevertheless, defining urban sub-catchments for rainfall-runoff modelling is often still performed manually using specific maps or using simple surface partitioning algorithms such as the Thiessen polygons. A significant disadvantage in generating urban sub-catchments manually is the fact that natural surface inclination is usually not considered, influencing the size and shape of the delineated sub-catchments. So far, only a few studies have devoted attention to improving the way urban sub-catchments are delineated and the information about their surface characteristics is generated. This study evaluates a GIS-based approach to automatically delineate urban sub-catchments accounting for the location of nodes (actual manholes or drain inlets) as sub-catchment outlets. In order to compare the influence of the sub-catchment delineation methods (1 to 3), we use (1) a digital surface model (DSM) and (2) a digital elevation model (DEM) to automatically delineate the urban sub-catchments and compare these two methods with each other as well as with (3) already manually derived sub-catchments of a specific case study. Furthermore, we compare hydraulic simulation results from the software SWMM with measured flow data to infer the most accurate sub-catchment delineation method.&lt;/p&gt;


2018 ◽  
Author(s):  
Rainer Feistel

Abstract. In the terrestrial climate system, water is a key player in the form of its different ambient phases of ice, liquid and vapour, admixed with sea salt in the ocean and with dry air in the atmosphere. For proper balances of climatic energy and entropy fluxes in models and observation, a highly accurate, consistent and comprehensive thermodynamic standard framework is requisite in geophysics and climate research. The new “Thermodynamic Equation of Seawater – 2010” (TEOS-10) constitutes such a standard for properties of water in its various manifestations in the hydrological cycle. TEOS-10 has been recommended internationally in 2009 by the Intergovernmental Oceanographic Commission (IOC) to replace the previous 1980 seawater standard, EOS-80, and in 2011 by the International Union of Geodesy and Geophysics (IUGG) “as the official description for the properties of seawater, of ice and of humid air”. This paper briefly reviews the development of TEOS-10, its novel axiomatic properties, new oceanographic tools it offers, and important tasks that still await solutions by ongoing research. Among the latter are new definitions and measurement standards for seawater salinity and pH, in order to establish their metrological traceability to the International System of Units (SI), for the first time after a century of widespread use. Of similar climatological relevance is the development and recommendation of a uniform standard definition of atmospheric relative humidity that is unambiguous and rigorously based on physical principles.


2018 ◽  
Vol 40 (1) ◽  
pp. 25-35 ◽  
Author(s):  
Danielle Helena Müller ◽  
Elisangela Clarete Camili ◽  
Walcylene Lacerda Matos Pereira Scaramuzza ◽  
Maria Cristina de Figueiredo e Albuquerque

Abstract: The objective of this study was to evaluate the spatial variability in soybean seeds quality and in soil chemical attributes of a production field. Data were collected at 138 georeferenced points of a soybean production property located in Santo Antônio de Leverger - MT. Soil related variables, such as phosphorus, potassium, calcium, magnesium, and organic matter (OM) contents, pH, cation exchange capacity (CEC) and base saturation (V%) were evaluated. On the other hand, yield, one thousand seed mass, size, germination, emergence in seedbed, electrical conductivity, accelerated aging and tetrazolium reaction were evaluated as seed variables. The data were submitted to descriptive and geostatistical analysis, and the fit semivariogram parameters were used to elaborate spatial distribution maps of the analyzed variables. After the analysis, it was possible to conclude that there was spatial variability in the evaluated attributes for both seeds and soil related variables, indicating that the soybean seed production area can be divided into management zones, which allows the definition of areas to be harvested or discarded within a field of seed production.


2019 ◽  
Vol 98 ◽  
pp. 12017
Author(s):  
Jelena Parlov ◽  
Zoran Kovač ◽  
Jadranka Barešić

Water stable isotopes were used to investigate hydrological pathways and interactions between surface water and groundwater in the Zagreb aquifer system (Croatia). δ2H and δ18O values indicate a spatial variability of the influence of individual groundwater sources inside the aquifer – local precipitation and the Sava River water. Fractions of surface water in groundwater strongly depend on fluctuations of the river water level and less on the distance from the Sava River. These data extend our understanding of groundwater flow in the Zagreb aquifer system, interactions between Sava River water, local precipitation and groundwater. The results of the research allow more precise monitoring plans and definition of the sanitary protection zones of the well fields in the future.


2011 ◽  
Vol 2 (2) ◽  
pp. 179-190 ◽  
Author(s):  
P. Porada ◽  
A. Kleidon ◽  
S. J. Schymanski

Abstract. Hydrological processes are irreversible and produce entropy. Hence, the framework of non-equilibrium thermodynamics is used here to describe them mathematically. This means flows of water are written as functions of gradients in the gravitational and chemical potential of water between two parts of the hydrological system. Such a framework facilitates a consistent thermodynamic representation of the hydrological processes in the model. Furthermore, it allows for the calculation of the entropy production associated with a flow of water, which is proportional to the product of gradient and flow. Thus, an entropy budget of the hydrological cycle at the land surface is quantified, illustrating the contribution of different processes to the overall entropy production. Moreover, the proposed Principle of Maximum Entropy Production (MEP) can be applied to the model. This means, unknown parameters can be determined by setting them to values which lead to a maximisation of the entropy production in the model. The model used in this study is parametrised according to MEP and evaluated by means of several observational datasets describing terrestrial fluxes of water and carbon. The model reproduces the data with good accuracy which is a promising result with regard to the application of MEP to hydrological processes at the land surface.


2021 ◽  
pp. 131-140
Author(s):  
G.KH. ISMAIYLOV ◽  
◽  
A. V. PERMINOV ◽  
I. G. ISMAIYLOVA

The article considers methodical approaches to the analysis of the current state of the management problem of water economic systems under non-stationarity of multi-year fluctuations of surface water resources. Application of the simulation modeling method for solving water management problems is substantiated. The main provisions of the analysis of initial hydrological information to control the operation regime of the Volga-Kama cascade of hydraulic units are given. Methodical provisions for the analysis of the operation regime of complex water management systems with a cascade of hydraulic units with reservoirs in its structure are formed. The operation modes of the Volga-Kama cascade of hydraulic units under the conditions of different water content of the Volga River are analyzed. The considered methodic provisions are illustrated by the examples of simulated modeling of the Volga-Kama cascade operational regime under average water content conditions. The structure of modern water management systems and their functioning is presented as an open multicomponent dynamic system. The ultimate goal of the analysis technique of the water management system with the knowledge of the regularities of hydrological system formation is development of formalized mathematical models of this system functioning and investigation of many alternative variants under different natural-economic conditions.


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