Groundwater dependent ecosystems. Part I: Hydroecological status and trends

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Environmental tracers as a tool in groundwater vulnerability assessment

Environmental tracers are physical properties and chemical components of water whose spatial and temporal differentiation is used to infer information on the pathways and dynamics of water and solutes movement through the environment. The quantitative and qualitative insights into the functioning of groundwater systems derived from tracer observations is useful for the physically based and operational assessments of vulnerability of groundwater quality to human pressures. This tracer-based information concerns identification of the hydraulic connections between the source areas of pollution and groundwater receptors and evaluation of the ability of the unsaturated and saturated zones to delay and attenuate spreading of pollutants. Particularly important are distributions of water transit times which can be inferred from tracer observations by use of the lumped parameter models. The transit time distributions contain information on the lag-times, attenuation and persistence of pollutants in groundwater systems and are a basis for designing various indexes of vulnerability. Despite the advantages of environmental tracers in vulnerability assessment and despite the advances in analytical techniques application of tracers in this field is limited. This work presents the understanding of groundwater vulnerability in the context of risk assessments, explains the basic concepts of the application of the environmental tracers, discusses potential applications of tracers in assessing the intrinsic groundwater vulnerability and briefly presents examples of such applications

Phosphorus Transport in a Lowland Stream Derived from a Tracer Test with 32P

Small streams in urbanized rural areas receive loads of P from various, often episodic, sources. This paper addresses, through a tracer test with 32P, retention and transport of a pulse input of phosphorus in a 2.6 km long stretch of a channelized second-order lowland stream. Tritiated water was introduced alongside the 32P-labelled ortophosphate in order to isolate the influence of the hydrodynamic factors on P behavior. Tracer concentrations in unfiltered water samples were measured by liquid scintillation counting. Four in-stream and five hyporheic breakthrough curves were collected at four points along the stream, two of which encompass a beaver dam impoundment. The overall retention efficiency of 32P along the studied reach was 46%. The transient storage transport model OTIS-P provided reasonable fits for in-stream breakthrough curves (BTCs) but failed at reproducing the hyporheic BTCs. The overall small effect of transient storage on solute transport was higher in the stretch with a more pronounced surface storage. Transient storage and phosphorus retention were not enhanced in the beaver dam impoundment

Data used in article "Self-calibration of UAV Thermal Imagery Using Gradient Descent"

This repository contains data allowing for reproduction of research described in article "Self-calibration of UAV Thermal Imagery Using Gradient Descent". Each zip archive available in repository contains: Thermal images produced using Zenmuse H20T camera (rjpg directory) Geojson vector shape of river centerline (centerline.json file) Configuration file used by Python implementation available at https://github.com/radekszostak/aerial-thermal-tuner (config.py file

Aquifer Vulnerability and Contamination Risk

Water supply systems must be designed in such a way to ensure groundwater extraction sustainability. In addition, the quality of pumped water must also be guaranteed, and this entails protecting the groundwater source from contamination. To do so, it is necessary to identify the physical and hydraulic characteristics of the soil, the unsaturated medium and the aquifer itself that influence the migration of contaminants spilled at the surface towards the aquifer, and hence potentially towards sensitive targets (i.e., drinking water pumping wells). The susceptibility of an aquifer to become polluted following a contaminant spill is called vulnerability, and its assessment is the focus of this chapter. Of the four categories of vulnerability assessment methods, i.e., overlay, index and statistical methods, and process-based simulation models, this chapter presents examples of the former two, which are of easier implementation and are widely used. Overlay methods define aquifer vulnerability on the basis of groundwater circulation and rely on the superposition of maps of the hydrogeologic, structural and morphologic setting. Index methods, instead, are based on the assignment of scores (sometimes weighed) to sets of parameters that are likely to affect the degree of vulnerability. Specific methods of these two categories described in detail in this chapter are the one developed by the Bureau de Recherches Géologiques et Minières in France, the Italian CNR-GNDCI and SINTACS methods, the US-EPA DRASTIC method and the British GOD method. The suitability of different methods is discussed, and how vulnerability assessment can be used to determine the risk of contamination is presented. On this basis, an example of contamination risk reduction strategies is illustrated

Urban CO2 Budget: Spatial and Seasonal Variability of CO2 Emissions in Krakow, Poland

Krakow, with an area of 327 km2 and over 750,000 inhabitants, is one of the largest cities in Poland. Within the administrative city borders several anthropogenic CO2 source types are located, including car traffic, household coal and natural gas burning, and industrial emissions. Additionally, the biosphere produces its own, seasonally variable, input to the local atmospheric carbon budget. In order to quantify each of CO2 budget contributions to the local atmosphere, a number of analytical and numerical techniques have been implemented. The seasonal variability of CO2 emission from soils around the city has been directly measured using the chamber method; CO2 net flux from an area containing several source types has been measured with a relaxed eddy accumulation—a variation of the eddy covariance method. Global emissions inventory, as well as local statistical data have been utilized to assess anthropogenic component of the budget. As other cities where CO2 budget was quantified, Krakow proved to be a net source of this greenhouse gas, and the calculated annual mean net flux of CO2 to the atmosphere equal 6.1 kg C m−2 is consistent with previous estimations

Self-Calibration of UAV Thermal Imagery Using Gradient Descent Algorithm

Unmanned aerial vehicle (UAV) thermal imagery offers several advantages for environmental monitoring, as it can provide a low-cost, high-resolution, and flexible solution to measure the temperature of the surface of the land. Limitations related to the maximum load of the drone lead to the use of lightweight uncooled thermal cameras whose internal components are not stabilized to a constant temperature. Such cameras suffer from several unwanted effects that contribute to the increase in temperature measurement error from ±0.5 °C in laboratory conditions to ±5 °C in unstable flight conditions. This article describes a post-processing procedure that reduces the above unwanted effects. It consists of the following steps: (i) devignetting using the single image vignette correction algorithm, (ii) georeferencing using image metadata, scale-invariant feature transform (SIFT) stitching, and gradient descent optimisation, and (iii) inter-image temperature consistency optimisation by minimisation of bias between overlapping thermal images using gradient descent optimisation. The solution was tested in several case studies of river areas, where natural water bodies were used as a reference temperature benchmark. In all tests, the precision of the measurements was increased. The root mean square error (RMSE) on average was reduced by 39.0% and mean of the absolute value of errors (MAE) by 40.5%. The proposed algorithm can be called self-calibrating, as in contrast to other known solutions, it is fully automatic, uses only field data, and does not require any calibration equipment or additional operator effort. A Python implementation of the solution is available on GitHub