Hydrological Practice Research Articles

Geo-Hydrobiology and Geoinformatics Mapping of Ethnobotany in the Gandhamardan Hills, Odisha, India

Objective: The Gandhamardan Hills (GMH)range is a group of small mountains in Peninsular India in Balangir district in Odisha state in India. There is uniqueness in geology, geography, geomorphology, climatology, Hydrology, petrology, and lithology. The lithology, soil, water, geomorphology, and traditional use of plants in Ayurveda (India) have holistic medicinal/surgery. origin. Geo-hydro-biological amalgamation through Geological Information Systems (GIS) and chemical analysis is still being explored, and the present research emphasises such studies. Methods: Data about geo-hydro-biology through grapy, geology, geomorphology, hydrology, and traditional medicinal practices are implored from literature sources, using TOPO and Q-GIS maps and ERDAS software; their analytical interpretations were reported. The chemical analysis was conducted using X-ray fluorescence spectrometric studies of the water and soil of GMH, and the exuberance of ethnobotanical species in GMH was correlated. Results Laboratory analysis, literature studies, and interaction with Ayurvedic and Kaviraj practitioners, 154 popular species databases with their pharmacological applications reported for ordinary people. Many species have multidimensional applications that can transform Ayurveda into Materia medica. Conclusion: This ethnobotanical study documented the use of plants by the local community. The natural medicinal plants are cheap for the rural communities. The information gathered can be used for further scientific investigation to develop new commercial plant-based medicines as they will be safer than synthetic drugs. SDGs 1 to 3 and 12, 13, and 15 will be satisfied if we can conserve and adequately manage the hub of medicinal plants in GMH.

An integrated design discharge calculation system for small to mid-sized ungauged catchments in Serbia

Abstract. This study deals with the application of freely available datasets on the global and local level coupled with open source GIS software in hydrological modelling, greatly improving cost and time effectiveness of hydrological analyses of ungauged catchments. The automated calculation system was developed as an extremely useful tool for hydrologists for the quick estimation of design discharges. The morphometric module of the calculation system showed excellent results, saving a great deal of time that would otherwise been spent on manual processing of geospatial data. Using the automated calculation system, the methodologies currently in use in hydrological practice in Serbia were evaluated. The distributed velocity method was introduced as a way of calculating hydrograph lag time. The comparison between design discharges calculated by rainfall-runoff analysis and by frequency analysis yielded very good resemblance. Examples of real-world application for over 2500 catchments are shown.

Skills Development in Hydrologic Sciences for Cohorts of Graduate Students from Morocco, Egypt, Türkiye, and Indonesia

AbstractIn developing countries in Africa and Asia, meeting challenges of water scarcity and pollution has often been hampered by shortcomings in higher education, including insufficient research productivity and funding, lack of opportunity for university graduates, and a mismatch between university activities and societal needs. To address these issues, we developed novel programs integrating technical instruction and preparation for professional practice in hydrology for cohorts of graduate students from Morocco and Egypt (2012–2013) and from Türkiye and Indonesia (2013–2014). Students participated in an initial online course and a follow‐up workshop featuring geographic information systems (GIS), remote sensing, and hydrologic modeling with internet‐based data sets. Field activities in the USA (first cohort) and in the students’ home countries (second cohort) included stream gauging, measurement of water levels in wells, water sampling, and measurement of hydrochemical parameters. A subsequent online course focused on research ethics, preparing proposals and publications, and presenting findings to technical audiences and the public, culminating in presentations at conferences in the USA. Participants mentored other students at their home institutions and at K‐12 schools in Türkiye and Indonesia. Participant feedback during and after the programs tended to be strongly positive, and participants have continued to engage with project leaders and mentor students in their home countries and the USA. Our modular, hybrid approach offers a template for students in hydrology and related fields to develop relevant skills and engage internationally.

Abrupt shift in the organic matter input to sediments in Lake Liangzi, a typical macrophyte-dominated shallow lake in Eastern China, and its response to anthropogenic impacts

Understanding the historical variations in organic matter (OM) input to lake sediments and the possible mechanisms regulating this phenomenon is important for studying carbon cycling and burial in lake systems; however, this topic remains poorly addressed for macrophyte-dominated lakes. To bridge these gaps, we analyzed bulk OM and molecular geochemical proxies in a dated sediment core from Lake Liangzi, a typical submerged macrophyte-dominated lake in East China, to infer changes in OM input to sediments over the past 169 years due to the intensification of human activities in the catchment. A relatively primitive OM input pattern was observed in ca. 1841–1965, during which the lowest hydrogen index (HI), short-chain n-alkane abundance, and n-C17/n-C16 alkane indicated minimal input from phytoplankton, whereas the high Paq (proxy of aquatic macrophyte input) and long-chain n-alkane abundance suggested dominant and subordinate inputs from submerged and emergent macrophytes, respectively. OM input transitioned during ca. 1965–1993, with the highest Paq and lowest long-chain n-alkane abundance, indicating an increase of submerged macrophyte input and concurrent decline of emergent macrophyte input, probably caused by hydrological regulation practices and land reclamation in the 1960s, respectively. A further shift in OM input was observed since ca. 1993, characterized by the beginning of an increase in phytoplankton input, as indicated by the greater HI, short-chain n-alkane abundance, and n-C17/n-C16 alkane in sediments. Moreover, a lower Paq and higher abundance of long-chain n-alkanes indicated a decline in input from submerged macrophytes and an elevated input from terrestrial plants. The increase in αβ-hopane abundance and homohopane index value indicated that petroleum-sourced OM was first introduced into the sediments. The causes of these OM input changes included nutrient influx associated with domestic and industrial discharge, aquaculture within the lake, and widespread deforestation and land clearance in the catchment.

Spatiotemporal variability identification and analysis for non-stationary climatic trends for a tropical river basin of India

The non-stationary behavior of climatic variables has been increasingly recognized as a challenge that disrupts the equilibrium of human-defined climate-based stationary processes, including hydrological and agricultural practices, and irrigation systems. This study aims to investigate long-term trends and non-stationarity in climatic variables across 23 stations of the Krishna River basin, India. Prominent trends in rainfall, temperature, and their extreme indices were identified using the Modified Mann-Kendall (MMK), Bootstrapped Mann-Kendall (BMK), and Sen's Slope Estimator tests, while the Innovative Trend Analysis (ITA) test uncovered hidden trends and potential shifts in climatic patterns. This study addresses a critical research gap by exploring both significant and hidden trends in climatic variables, providing a better understanding of future dynamics. Traditional methods like MMK and Sen's Slope were insufficient to reveal these hidden trends, but ITA offered a more comprehensive analysis. The findings revealed an increase in total annual rainfall for almost 50% of the basin, which aligns with rising maximum temperatures, suggesting enhanced evaporation rates and subsequent fluctuations in rainfall patterns. Seasonal analysis indicated a shift towards decreased rainfall during winter and pre-monsoon seasons, contrasted by increased precipitation during the monsoon and post-monsoon periods, highlighting a clear alteration in rainfall distribution. The Simple Daily Intensity Index (SDII) and other indices suggest intensified rainfall events despite a decrease in the number of rainy days, indicating fewer but more intense events. Temperature analysis showed an overall increase in maximum temperatures, with the Diurnal Temperature Range (DTR) significantly increasing across all stations, implying greater daily temperature variations and potential for intensified water cycles and extreme climatic events. Furthermore, the study simplifies these trends by classifying them into two attributes: intensity and frequency, aiding policymakers in site-specific management of water resources and planning for future climatic scenarios. The presence of non-stationarity in extreme rainfall was confirmed by the Augmented Dickey-Fuller (ADF), Phillips-Perron (PP), and Kwiatkowski-Phillips-Schmidt-Shin (KPSS) tests. These findings are significant as they conclude how climate change is altering hydrological patterns at each station. The study emphasizes the necessity for adaptive management strategies to mitigate the adverse impacts on agriculture, infrastructure, and human safety.

Quantifying ‘realistic’ uncertainty bounds as a part of sound hydrological modelling practice in data scarce regions of southern Africa

This study was based on two premises; the ultimate objective of hydrological modelling is a contribution to sustainable water resources management, and the inherent uncertainties in model results should be realistically quantified. The study uses methods of uncertainty analysis that have been previously applied in the southern Africa region which are based on constraining model outputs using the likely ranges of a set of hydrological indices. One objective was to offer suggestions for sound modelling practice and highlight potential problems. The approach is applied to two case studies where there are very limited streamflow observations. The uncertainty ensemble outputs from the hydrological model are input into a water supply allocation model to assess system performance under different abstraction scenarios. The results are compared with the limited available evidence of system performance and the conclusion is that the uncertainty bands are generally acceptable for future decision making.

GNSS-IR water level monitoring toward particular narrow scenarios: Application to South-to-North Water Diversion Project in China

River water level monitoring plays a crucial role in hydrological practice. Global Navigation Satellite Systems Interferometry Reflectometry (GNSS-IR) has been demonstrated to help retrieve absolute water levels in expansive and unobstructed scenarios. However, how to measure in rivers remains a significant challenge for practical use due to the restricted reflection area. To address these issues, we propose the Dynamic Masking Elevation Threshold Selection Method (DMETSM), which effectively broadens the selection of available reflective signals. Through analyzing actual field data collected along the South-to-North Water Diversion Project, we have found that DMETSM almost doubles the effective monitoring area compared to the classical method. Furthermore, the multi-GNSS water level retrievals at two sites can achieve high accuracy, with root-mean-square errors of 1.36 cm and 2.57 cm, respectively. Results show that it improves accuracy by 30.6 % and 42.6 %. This highlights the considerable potential and value of applications in narrow and irregular areas.

Rainfall Deviation of India from the Last 40 Years Data Using Remote Sensing

This research investigates precipitation deviations using the Climate Hazards Group InfraRed Precipitation with Station (CHIRPS) dataset within the Google Earth Engine (GEE) platform. CHIRPS, developed by the Climate Hazards Group at the University of California, Santa Barbara, in collaboration with the U.S. Geological Survey, provides high-resolution daily precipitation data from 1981 to the present. Leveraging its spatial resolution of 0.05 degrees, we analyzed precipitation patterns over a specified region from 1982 to 2022. The methodology involves comprehensive data preprocessing, including loading, subsetting, and handling missing values using JavaScript in GEE. Climatology was calculated by aggregating the data monthly to establish a baseline of expected precipitation patterns. Deviations from this baseline were computed to identify anomalies. The CHIRPS dataset’s integration into GEE enabled robust spatial and temporal visualization and statistical analysis of precipitation anomalies. This study underscores CHIRPS’s crucial role in enhancing our understanding of precipitation variability, informing climate adaptation strategies, and improving hydrological, agricultural, and disaster risk management practices. The findings contribute valuable insights into precipitation trends and their implications in the context of global climate change.

Revisiting the greenhouse effect – a hydrological perspective

ABSTRACT Quantification of the greenhouse effect is a routine procedure in the framework of hydrological calculations of evaporation. According to the standard practice, this is made considering the water vapour in the atmosphere, without any reference to the concentration of carbon dioxide (CO2), which, however, in the last century has increased from 300 to about 420 ppm. As the formulae used for the greenhouse effect quantification were introduced 50–90 years ago, we examine whether these are still representative or not, based on eight sets of observations, distributed across a century. We conclude that the observed increase of the atmospheric CO2 concentration has not altered, in a discernible manner, the greenhouse effect, which remains dominated by the quantity of water vapour in the atmosphere, and that the original formulae used in hydrological practice remain valid. Hence, there is no need for adaptation of the original formulae due to increased CO2 concentration.

Využití srážkoodtokového modelování v hydrologické praxi ČHMÚ

Rainfall-runoff modelling is widely used in the hydrological practice of the CHMI. The presented text offers an insight into work of the Surface Water Department. The use of hydrological modelling procedures is described on specific selected examples such as the derivation of theoretical flood waves, the evaluation and verification of past flood events or its use in several applications operated at the CHMI. Hydrological modelling is also an integral part of scientific and research activities with a focus on updating methodological procedures and harmonizing input data.

Derivation of long duration geographically-centred areal reduction factors for catchment design rainfall estimation in South Africa

Study regionSouth Africa. Study focusThe use of Areal Reduction Factors (ARFs) to convert average design point rainfall into areal catchment design rainfall is regarded as fundamental input to event-based deterministic design flood estimation methods. The ARF methods currently used in South Africa are outdated and were neither developed nor verified using local data. This paper presents the development and assessment of a regionalised approach to estimate long duration (≥ 1-day) geographically-centred ARFs using daily rainfall data representative of the 78 homogeneous long duration rainfall clusters associated with the Regional Linear Moment Algorithm and Scale Invariance (RLMA&SI) regionalisation scheme in South Africa. In order to meet the recommended World Meteorological Organisation rainfall station density criteria, the latter clusters were merged into 46 clusters. Subsequently, long duration geographically-centred sample ARFs were estimated using 2 053 circular catchments and 1 779 daily rainfall stations. New hydrological insights for the regionFive ARF regions were deduced from the 46 clusters and a single regional empirical ARF equation, with unique regional calibration coefficients, was derived. The ARF methodology developed and the subsequent findings are not only new to the South African flood hydrology community and practice, but are also probabilistically correct given that the ARF estimates decrease with an increasing catchment area and decrease with a decreasing storm duration and return period, unlike many other methods used internationally.

National-scale nitrogen loading from the Finnish agricultural fields has decreased since the 1990s

The national scale nutrient load modelling system VEMALA-ICECREAM was used to simulate agricultural total nitrogen(TN) loading and its trends for all Finnish watersheds for the period from 1990–2019. Across Finland, agricultural TN loading (ATNL) has decreased from 17.4 kg ha-1 a-1 to 14.4 kg ha-1 a-1 (moving 10-year averages) since the 1990s. The main driver of the decrease in simulated ATNL is a reduction in mineral fertilizer use, which has decreased the N surplus in the soils. The TN leached fraction, however, did not show a trend but did have high annual variability due to variations in runoff; this corresponds to an average of 14.4% of the TN applied. The ATNL was considerably higher in the Archipelago Sea catchment compared to other Finnish Baltic Sea sub-catchments, with the lowest ATNL found in the Vuoksi catchment in Eastern Finland. The highest decrease of ATNL was simulated for Vuoksi and Gulf of Finland catchments. In the Bothnian Sea, Bothnian Bay and Archipelago Sea catchments, the decreasing trend of ATNL was smaller but still significant, with the exception of the Quark catchment, where there was no significant change. The differences in decreasing trends between regions can be explained by the heterogeneity of catchment characteristics, hydrology and agricultural practices in different regions.

Species Composition and Population Dynamics of Culicidae during their Peak Abundance Period in Three Peri-Urban Aquatic Ecosystems in Northern Spain

For a better understanding of the transmission cycles of mosquito-borne diseases, it is essential to explore the species composition and population dynamics, mainly during their peak abundance period. These investigations do not normally include peri-urban areas, despite their significant epidemiological interest. To address these gaps, an entomological survey was carried out in 2016 and 2017 in three aquatic ecosystems located on the outskirts of the city of Logroño, in northern Spain: the Iregua River and La Grajera (La Rioja) and Las Cañas Reservoirs (Navarra). Mosquitoes were captured using BG-Sentinel traps baited with CO2 and BG-lure, as well as through the human landing collection method. In total, 6793 mosquito specimens were captured, representing 24 taxa within six genera. A specific PCR based on the ITS2 gene was used to differentiate members of the Anopheles claviger complex, and all individuals were identified as An. claviger sensu stricto. La Grajera had the most diverse culicid fauna, with 19 taxa, followed by Las Cañas (n = 15) and the Iregua River (n = 13). The composition and abundance of Culicidae varied across the aquatic ecosystem. We observed that the different hydrological management practices of each environment could play a key role in determining the abundance of mosquito genera. The overall risk of mosquito bites in the study area is expected to be relatively low and will depend on the freshwater ecosystem and the time of year.

Relevance of charge interactions for contaminant transport in heterogeneous formations: a stochastic analysis

The electrostatic properties of clay (or other charged) mineral surfaces play a significant role in the fate, transport, persistence, and remediation of subsurface contaminant plumes. This study presents a stochastic assessment of the impact and relevance of microscale electrostatic effects on macroscopic, field-scale contaminant transport in heterogeneous groundwater systems involving spatially distributed clay zones. We present Monte Carlo simulations in two-dimensional heterogeneous fields, comprising heterogeneous distributions of physical (i.e., hydraulic conductivity, porosity, tortuosity) and electrostatic (i.e., surface charge) properties, and compare scenarios with different combination and extent of physical and electrostatic processes. The simulations were performed with the multi-continua based reactive transport code, MMIT-Clay, and considering an explicit treatment of the diffuse layer processes. The results reveal that the microscopic electrostatic mechanisms within clay’s diffuse layer can significantly accelerate or retard a particular contaminant depending on its charge, leading to considerably different solute breakthroughs and mass loading/release behaviors in low permeability inclusions. Furthermore, we show that such variations in the macroscale transport behavior, solely driven by charge interactions, are statistically significant over the ensembles of Monte Carlo realizations. The simulations also demonstrate that the omission of electrostatic processes, which is still a common practice in subsurface hydrology, can lead to substantial over- or underestimation of contaminant migration.

In Defense of Metrics: Metrics Sufficiently Encode Typical Human Preferences Regarding Hydrological Model Performance.

Building accurate rainfall-runoff models is an integral part of hydrological science and practice. The variety of modeling goals and applications have led to a large suite of evaluation metrics for these models. Yet, hydrologists still put considerable trust into visual judgment, although it is unclear whether such judgment agrees or disagrees with existing quantitative metrics. In this study, we tasked 622 experts to compare and judge more than 14,000 pairs of hydrographs from 13 different models. Our results show that expert opinion broadly agrees with quantitative metrics and results in a clear preference for a Machine Learning model over traditional hydrological models. The expert opinions are, however, subject to significant amounts of inconsistency. Nevertheless, where experts agree, we can predict their opinion purely from quantitative metrics, which indicates that the metrics sufficiently encode human preferences in a small set of numbers. While there remains room for improvement of quantitative metrics, we suggest that the hydrologic community should reinforce their benchmarking efforts and put more trust in these metrics.

A Critical Review and Bibliometric Analysis on Applications of Ground Penetrating Radar in Science Based on Web of Science Database

Ground-penetrating radar (GPR) is an established technology with a wide range of applications for civil engineering, geological research, archaeological studies, and hydrological practices. In this regard, this study applies bibliometric and scientometric assessment to provide a systematic review of the literature on GPR-related research. This study reports the publication trends, sources of publications and subject categories, cooperation of countries, productivity of authors, citations of publications, and clusters of keywords in GPR-related research. The Science Citation Index Expanded (SCI-EXPANDED) and the Social Sciences Citation Index (SSCI), which can be accessed through the Web of Science Core Collection, are used as references. The findings report that the number of publications is 6880 between 2001 and 2021. The number of annual publications has increased significantly, from 139 in 2001 to 576 in 2021. The studies are published in 894 journals, and the annual number of active journals increased from 68 in 2001 to 215 in 2021. Throughout the study, the number of subject categories involved in GPR-related research fluctuated, ranging from 38 in 2001 to 68 in 2021. The research studies originated from 118 countries on 6 continents, where the United States and the People’s Republic of China led the research articles. The top five most common keywords are ground-penetrating radar, non-destructive testing, geophysics, electrical resistivity tomography, and radar. After investigating the clusters of keywords, it is determined that civil engineering, geological research, archaeological studies, and hydrological practices are the four main research fields incorporating GPR utilization. This study offers academics and practitioners an in-depth review of the latest research in GPR research as well as a multidisciplinary reference for future studies.

Assessing Plastic Waste Discharges into the Sea in Indonesia: An Integrated High-Resolution Modeling Approach That Accounts for Hydrology and Local Waste Handling Practices

Plastic litter is increasingly accumulating in the marine environment, with rivers considered key pathways for entry. Current estimations of plastic input into the sea from land-based sources are limited in accounting for the mobilization and transport of plastic generated in the whole catchment area or in considering local variations in waste handling practices. Here, we show that, with an integrated discharge modeling approach (based on actual rainfall and local estimates for exposed mismanaged plastic waste), more realistic temporal estimates of plastic discharges into the sea can be constructed. Applying this approach to Indonesia enabled us to estimate the total national inputs of plastic waste into the sea from rivers and coasts and how these vary with rainfall, while providing insight into those catchments, local communities, and waste handling practices that most contribute to plastic waste leakages. We found that the plastic fluxes vary significantly in both the short and long term and that the total amount of plastic waste discharged during wet years may be twice as much as during dry years. Furthermore, river size, catchment population density, local waste management, and proximity of point sources influence river plastic waste loads. Such an integrated assessment can be very effective in helping to prioritize where interventions are most needed and, in combination with frequent monitoring, can provide evidence of the impact that upstream measures have on preventing plastic inputs into the sea.

The Copula Application for Analysis of the Flood Threat at the River Confluences in the Danube River Basin in Slovakia

In hydrological practice, individual elements of the hydrological cycle are most often estimated and evaluated separately. Uncertainty in the size estimation of extrema discharges and their return period can affect the statistical assessment of the significance of floods. One example is the simultaneous occurrence and joining of extremes at the confluence of rivers. The paper dealt with the statistical evaluation of the occurrence of two independent variables and their joint probabilities of occurrence. Bivariate joint analysis is a statistical approach for the assessment of flood threats at the confluence of rivers. In our study, the annual maximum discharges monitored on four selected Slovak rivers and their tributaries represent the analyzed variables. The Archimedean class of copula functions was used as a set of mathematical tools for the determination and evaluation of the joint probability of annual maximal discharges at river confluences. The results of such analysis can contribute to a more reliable assessment of flood threats, especially in cases where extreme discharges occur simultaneously, increasing the risk of devastating effects. Finally, the designed discharges of the different return periods calculated by using the univariate approach and the bivariate approach for the gauging station below the confluence of the rivers was evaluated and compared.

法律元素融入《地下水水文学》课程教学的探索与实践

法律元素融入《地下水水文学》课程教学的探索与实践

Agricultural nitrate export patterns shaped by crop rotation and tile drainage

Excessive agricultural nitrate export to aquatic systems degrades water quality and causes downstream ecological crises. Limited understanding of their underlying mechanisms and controls hinders mitigation measures. Here we analyzed observations of nitrate concentration (C) and discharge (Q) in 83 intensively managed agricultural watersheds across the central U.S. Midwest (37.0–44.5 N, 97.5–80.0 W), which reveals a regionally consistent pattern in C∼Q relationships: C∼Q relationship is chemodynamic at low flows and chemostatic at high flows, i.e., C increases with Q until a threshold beyond which C levels off. Motivated by this universal pattern, we developed a coupled model at the event scale that involves mixing of quick flow with high nitrate levels coming from shallow soils and the slow flow with low nitrate levels coming from deeper soils. Its implementation in combination with seasonal patterns of hydrology and agricultural practices explains observed patterns in the C∼Q relationship across broad spatial and temporal scales and quantifies their main driving factors. Agricultural practices (i.e., corn fraction, nitrogen fertilizer use) explain 49% of spatial variability of C in quick flow during peak season, whereas tile drainage explains another 25%. Scenario analysis of changing area fraction of tile and corn using model projections sheds light on plausible pathways to assess and implement nutrient loss reduction goals.