Hydrological Properties Research Articles

A Signature‐Based Hydrologic Efficiency Metric for Model Calibration and Evaluation in Gauged and Ungauged Catchments

AbstractRainfall‐runoff models are commonly evaluated against statistical evaluation metrics. However, these metrics do not provide much insight into what is hydrologically wrong if a model fails to simulate observed streamflow well and they are also not applicable for ungauged catchments. Here, we propose a signature‐based hydrologic efficiency (SHE) metric by replacing the statistical components of current efficiency metrics with hydrologic signatures that can be regionalized for model evaluation in ungauged catchments. We test our new efficiency metric across 633 catchments from Great Britain. Strong correlations with Spearman rank and Pearson correlation values around 0.8 are found between our proposed metric and commonly used statistical evaluation metrics (NSE, KGE, and NP) demonstrating that the proposed SHE metric is related to existing metrics as much as these metrics are related to each other. For ungauged catchments, we regionalize the three signatures included in SHE and find that 78% of catchments have an absolute difference of SHE values between gauged and ungauged cases of less than 0.2. This difference varies depending on the quality of the regionalized bias and variance signature values. It means that the SHE metric is applicable for model evaluation in ungauged catchments if its signatures can be regionalized well. When applying the SHE metric in other domains with different hydrologic properties, modellers should carefully consider the components of the proposed metric with signatures best suited to their research domains and their regionalization potential.

Research and application of coral reef limestone similar material development and model testing

Abstract: To develop suitable similar materials for underground engineering model tests on islands, a series of experiments were conducted on various types of coral reef limestones in the South China Sea region. Using calcareous sand, white cement, silicone oil, and purified water as raw materials, 25 groups of orthogonal proportion tests and sensitivity analyses of different factors were performed on coral reef limestone similar materials. The reliability of the similar materials was also verified through laboratory-scale model tests. The study indicates that four groups of similar materials were formulated, which are closely related to the physico-mechanical properties and hydrological properties of different coral reef limestones. Among them, when the ratio of white cement to calcareous sand exceeds 1/12, it predominantly affects the physical and mechanical properties of the similar materials; when the ratio of silicone oil to white cement exceeds 1/3, it has better regulatory effects on the coefficient of permeability of similar materials. The content of purified water is negatively correlated with the compressive strength and elastic modulus of the similar materials, exerting a greater influence when it exceeds 20% of the total mass. Based on the multiple linear regression method for analyzing the test results, an empirical formula for the proportion of coral reef limestone similar materials was established. This allows for the precise calculation and formulation of different types of coral reef limestone similar materials, which can be widely applied to model testing and research in marine, geological, and geotechnical engineering.

Effect of straw incorporation on controlling runoff and soil erosion in cropland with different land degradation degrees

AbstractStraw incorporation plays a vital role in regulating runoff and soil erosion of cropland. However, the benefits of straw incorporation to control runoff and soil erosion on croplands under different degradation degrees have not been fully clarified. This study was performed to investigate the benefits of straw incorporation to reduce runoff and soil erosion under different degradation degrees and determine its dominant influencing factors. The event runoff and soil erosion were measured from late May to late September 2022 using 16 runoff plots (9 m in length and 3.3 m in width) in the black soil region of Northeast China. The results showed that straw incorporation significantly reduced runoff and soil erosion on croplands with different degradation intensities. Compared to croplands without straw incorporation, runoff and soil erosion of straw incorporation decreased by 48. 8%, 40.0%, 30.9%, 25.5%, and 55.2%, 48.8%, 40.8%, and 36.5% for croplands of no, light, moderate, and strong degradation intensities, respectively. The roles of straw incorporation in controlling runoff and erosion decreased with rainfall intensity. Compared to light rainfall, runoff reduction ratio and erosion reduction ratio of moderate and heavy rainfalls reduced by 19.5%–61.3% and 27.5%–64.4%. The benefit of straw incorporation to control runoff and erosion was limited on strong degraded cropland or under heavy storm. Moreover, soil hydrological properties and crop growth characteristics decreased by land degradation and improved by straw incorporation, which inevitably affected runoff and soil erosion. Soil bulk density, maximum rainfall intensity of 30‐min, saturated water content, precipitation, rainfall intensity, saturated hydraulic conductivity, and total porosity were the dominant factors affecting the roles of straw incorporation in controlling runoff and erosion on degraded croplands. The results of this study are helpful to prevent land degradation or recover the functions of degraded lands in semi‐humid region.

Biochar improves soil properties and corn productivity under drought conditions in South Korea

Biochar has been shown to improve soil properties and plant productivity in soils with inherently low fertility. However, little has been reported for upland corns under dry and wet precipitation regimes. This study investigates the effect of biochar addition on a range of soil physicochemical, biological, and hydrological properties, and corn growth and productivity under agrometeorological drought and wet conditions. Here, experiments were laid out in a randomized complete block design with three replications at two sites during 2017 and 2018 in South Korea. Treatments included (i) CN: control (ii) IF: inorganic fertilizer (N–P–K) at 145–30–60 kg ha−1; (iii) BS: barley straw at 5 t ha−1; (iv) CWBC: corn waste biochar at 5 t ha−1; (v) CWBC + IF: corn waste biochar + inorganic fertilizer; (vi) CWBC + BS: corn waste biochar + barley straw. The year 2017 was relatively dry, whereas the year 2018 was wet. Despite drought conditions in the year 2017, biochar facilitated soil water conservation. However, higher precipitation in 2018 increased the quantity and distribution of soil water and nutrients in the top 15 cm. Biochar reduced soil bulk density, and increased porosity, cation exchange capacity and total organic carbon in both years but increased total bacterial counts during the dry year only. Bacterial population was generally higher under wet conditions. Similarly, more soil CO2 was emitted in the wet year than in the dry year. Results further indicated that biochar can enhance corn biomass and grain yield regardless of precipitation conditions. The grain index was, however, affected by rainfall and was significantly different across treatments in the year 2018 only. All biomass, grain yield, and grain index were highest in CWBC + IF treatment and lowest under CN treatment. Indeed, biochar addition appeared to improve soil quality and soil conditioning effects in the drought and wet years, ameliorating soil and plant properties. Overall, biochar can improve water and nutrients storage, availability, and uptake, and therefore corn productivity during hydrological extremes.Graphical abstract

Effect of Different Tillage and Residue Management Options on Soil Water Transmission and Mechanical Behavior

Understanding the variability in the mechanical and hydrological soil characteristics resulting from diverse tillage and residue management practices is essential for evaluating the adoption of conservation strategies to preserve soil’s physical well-being. Zero-tillage techniques combined with residue retention or incorporation have gained widespread recognition for their capacity to conserve soil and water resources, reduce energy consumption, and enhance soil quality and environmental sustainability. Nevertheless, the choice of tillage and residue management options may vary depending on the geographical locations and specific soil conditions. To assess the impacts of four distinct tillage and residue management approaches, a two-year experiment (2020–2021 and 2021–2022) was conducted: T1: conventional tillage followed by wheat sowing after the removal of rice straw (CT-RS); T2: zero tillage with wheat sowing using a Happy Seeder while retaining rice straw (ZT+RS); T3: conventional tillage followed by wheat sowing after rice straw incorporation using a reversible mouldboard plough (CT+RS); T4: minimum tillage with wheat sowing using a Super Seeder with rice straw incorporation (MT+RS); the effects were recorded on the physical soil properties. Our findings indicate that zero tillage combined with residue retention (T2) had a positive influence on various physical soil attributes. Notably, significant differences were observed among the tillage and residue management options, particularly in terms of the bulk density with T1 exhibiting the highest values and the lowest being in T2, whereas the soil penetration resistance was lowest in T3 compared to T1. In the case of T3, sandy loam and clay loam soils had the highest measured saturated hydraulic conductivity values, measuring 5.08 and 4.57 cm h−1 and 4.07 and 3.73 cm h−1, respectively. Furthermore, T2 (zero tillage with residue retention) demonstrated the highest mean weight diameter (MWD) and maximum water stable aggregate. These results collectively underscore the positive effects of adopting zero tillage and retaining residue (T2) on soil structure and quality, particularly concerning the mechanical and hydrological soil properties.

Quantifying streamflow properties using a calculus‐based differential approach

AbstractThis research quantifies streamflow temporal configuration and demonstrates the advantages of examining the hydrologic record on a day‐to‐day basis, heretofore unavailable with statistical‐based index parameters. The streamflow chronological structure represents a previously untapped wealth of information that would benefit ecohydrology allowing alternate lines of investigation, re‐evaluating past research in a new light and expanding analysis options for ecohydrologists. Innovative approaches are introduced to quantify this important but overlooked hydrologic property. To accomplish this, a non‐index calculus‐based differential approach has been developed using the lag(1) temporal autocorrelation signature of streamflow. The techniques for quantifying discharge (Q), day‐to‐day discharge change (dQ/dt), rate of day‐to‐day discharge change (d2Q/dt2) and sequential discharge summations are explained and presented using updated data visualization methods. A dam release river impact case study for the Colorado River at Lees Ferry, Arizona, demonstrates this novel way of analyzing and comparing discharge datasets. A set of highly customizable tools for this new approach can be used as a stand‐alone analysis or to complement other existing techniques. The result is a better understanding of the hydrologic regime, permitting more focused research and more effective management planning.

Transformation of Soils and Mire Community Reestablishment Potential in Disturbed Abandoned Peatland: A Case Study from the Kaliningrad Region, Russia

Degrading organic soils usually become a source of increased greenhouse gas emissions and fire frequency in disturbed peatlands. As a solution, the rewetting concept should consider not only the detailed hydrological characteristics of the peatland, but should also appraise the properties of the soils. Here, we provide the results of a detailed soil study carried out on an abandoned peatland in the Kaliningrad Region, Russia. The study aims to integrate data on soil properties, hydrology, and the degree of transformation of the current soil cover in terms of how this affects spontaneous revegetation and the potential for further mire community reestablishment. The paper contributes to a greater understanding of rehabilitation patterns of disturbed peatlands depending on the soil’s physical and hydrological properties in the humid climate of the southeastern Baltic region. The present-day soils of the peatland refer to two World Reference Base (WRB) groups: Gleisols and Histosols; the latter change successively from the periphery to the centre of the peatland as follows: Eutric/Sapric → Hemic → Dystric → Fibric. Most Histosols are characterised by hydrothermal degradation in the upper layers with patches of pyrogenic degradation. Some local inundated areas show environmental conditions favourable for Sphagnum growth and the formation of mire communities. We have identified six groups of sites with different ecological and time-span potentials for mire community restoration during the implementation of rewetting activities. The rewetting feasibility of the peatland’s sites does not coincide with the degree of transformation of their soil profile, but is rather determined by the hydrological regime.

Land use/land cover change and soil property variation increased flood risk in the black soil region, China, in the last 40 years

Land use/land cover change and soil property variation driven by agricultural development substantially affect hydrological processes. Although previous studies have shown that land use/land cover change increases flood risk, how much soil property variation contributes to changes in water yield remains unclear in large-scale regions. Quantifying the water yield response to long-term land use/land cover change and soil property variation in agricultural regions is critical for flood risk control. The black soil area in China was chosen as the study area, and land use/land cover change, soil property variation, and changes in water yield during 1980–2020 were estimated. Land use/land cover change and soil property variation scenarios were established to separate the contributions of land use/land cover change and soil property variation to changes in water yield. The results showed that cultivated land and urban land expanded from 1980 to 2020. The plant available water capacity decreased by 2.10% and 7.27% in the black soil area and typical black soil area, respectively, and the water yield increased by 5.52% and 8.49% in the black soil area and typical black soil area, respectively. Land use/land cover change and soil property variation accounted for 58.64% and 36.67% of the increase in water yield in the black soil area. However, in comparison to land use/land cover change (47.40%), soil property variation (48.77%) accounted for a larger portion of the increase in water yield in the typical black soil area. Both land use/land cover change and soil property variation increased flood risk, however, the effects of soil property variation may exceed those of land use/land cover change, as determined by the spatial scale. This study can provide important information for land use planning and soil hydrological property improvements to reduce flood risk.

Water Quality Degradation Due to Heavy Metal Contamination: Health Impacts and Eco-Friendly Approaches for Heavy Metal Remediation.

Water quality depends on its physicochemical and biological parameters. Changes in parameters such as pH, temperature, and essential and non-essential trace metals in water can render it unfit for human use. Moreover, the characteristics of the local environment, geological processes, geochemistry, and hydrological properties of water sources also affect water quality. Generally, groundwater is utilized for drinking purposes all over the globe. The surface is also utilized for human use and industrial purposes. There are several natural and anthropogenic activities responsible for the heavy metal contamination of water. Industrial sources, including coal washery, steel industry, food processing industry, plastic processing, metallic work, leather tanning, etc., are responsible for heavy metal contamination in water. Domestic and agricultural waste is also responsible for hazardous metallic contamination in water. Contaminated water with heavy metal ions like Cr (VI), Cd (II), Pb (II), As (V and III), Hg (II), Ni (II), and Cu (II) is responsible for several health issues in humans, like liver failure, kidney damage, gastric and skin cancer, mental disorders and harmful effects on the reproductive system. Hence, the evaluation of heavy metal contamination in water and its removal is needed. There are several physicochemical methods that are available for the removal of heavy metals from water, but these methods are expensive and generate large amounts of secondary pollutants. Biological methods are considered cost-effective and eco-friendly methods for the remediation of metallic contaminants from water. In this review, we focused on water contamination with toxic heavy metals and their toxicity and eco-friendly bioremediation approaches.

Environmental factors and prey availability determine wintering habitat use by shorebirds along the west coast of India.

The spatial and temporal factors governing shorebird habitat use are crucial for managing coastal habitats and halting the decline of shorebird populations in the Central Asian Flyway. Therefore, we investigated how environmental variables and prey availability influenced shorebird distribution and abundance across habitats and seasons along the west coast of India between January 2015 and December 2016. Systematic sampling design was followed to collect data on shorebirds, sediment and hydrological properties (organic matter and physico-chemical properties), and prey availability across habitats over different seasons. Prey density and environmental variables such as salinity, organic matter, and sediment moisture content differed significantly across habitats and seasons. Prey density was influenced by salinity, with higher densities in mudflats (>1000 individuals per m2) during the winter season. Prey density decreased considerably in all coastal habitats during the departure (748.45 ± 320.93) and breeding seasons (537.55 ± 342.29). The fluctuations in prey density and salinity levels had a strong influence on distribution and abundance of shorebirds. These findings highlight the importance of mudflats as a foraging ground during the winter and freshwater inflow in maintaining salinity in estuarine habitats. Therefore, any alteration of river flow (e.g., construction of dams and check dams) or mudflats (e.g., mangrove plantations) would have a serious impact on the availability of prey organisms and the population of shorebirds that depend on them along the Central Asian Flyway.

Hydrological Properties of Rill Erosion on a Soil from a Drought-Prone Area during Successive Rainfalls as a Result of Microorganism Inoculation

Soil and water loss is one of the most severe kinds of land degradation, particularly in drought-vulnerable regions. It diminishes fertility and increases natural catastrophes, such as floods, landslides, sedimentation, drought, and economic, social, and political issues. The current study explores the efficacy of individual and combination cyanobacteria and bacteria inoculation on runoff production from plots generated by rill erosion on soil from the Marzanabad drought-prone region, northern Iran, and exposed to five successive rainfalls with three days intervals. Experiments were conducted on mid-sized plots with dimensions of 6 × 1 m, three replications, and a 30% slope during simulated rains at the lab with an intensity of 50 mm h−1 and a duration of 30 min. Also, excess runoff of about 2.180 L min−1 was introduced to the plots to promote rill formation. Because none of the treated plots created runoff during the design rainfall, the expected circumstances were subject to continuous rainfall until runoff was generated. Compared to the control plots, statistical analysis indicated that the study treatments had a significant (p < 0.01) lower influence on hydrological components during the initial rainfall event. The highest performance was obtained in the combination inoculation of cyanobacteria and bacteria in successive rainfalls (i.e., first to the fourth event), which reduced runoff volume and coefficient by 35.41, 45.34, 26.35, and 36.43%, respectively. During subsequent rainfalls, the bacteria and combination treatment of cyanobacteria and bacteria did not vary substantially (p = 0.94) on the study components. As a result, after consecutive rainfall events, runoff volume dropped by 20.79, 22.15, 12.83, and 15.87%, and the runoff coefficient reduced by 20.80, 22.15, 12.84, and 15.88%. The cyanobacteria treatment diminished the study components only after the initial rainstorm event. The current study’s findings underscored the need to minimize water loss in the early phases of erosion in drought-sensitive regions where soil and water conservation is a vital task.

Algorithm for Automating Input and Processing of Initial Data for Computer Forecasting of Spatial Migration of Radionuclides in Soils

An important tool for solving problems associated with the migration of radionuclides is computer technology that makes it possible to predict the spread of radioactive contamination in soils, which are an important component of the biosphere. At the same time, most modern software for the prediction of the spread of radioactive contamination is based on idealizations that simplify the understanding of this process, while solving the problem of a comprehensive assessment of the biosphere requires the use of a full-fledged spatial model of radionuclide migration in soils. Such a model was developed by P. K. Shalkevich within SPS (Simulation of Processes in Soil) software. SPS uses the initial values of radionuclide concentrations, hydrological and thermal properties of soils and information about meteorological conditions as input data for forecasting. At the same time, the listed initial data must be previously collected, processed and converted into a form that the software able to work with. Such processes require significant intellectual and time costs. These costs negatively affect the possibility of generating operational forecasts of the radioactive situation, but can be significantly reduced by using systems for automated radiation monitoring of soils and automating input and processing of initial data when predicting the spatial migration of radionuclides in the appropriate software, what is considered in the present article.

Гидрологические условия формирования фитоценозов на рекультивированных отвалах угольных шахт

Purpose: Study of the hydrological conditions for the formation of phytocenoses on reclaimed colliery spoil heaps. The state of the formed phytocenosis on the surface of the reclaimed colliery spoil heap has been studied. Experiments have been carried out in field conditions to determine the permeability of the spoil material of the reclaimed spoil heap. The influence of hydrological conditions on the formation of phytocenoses in quasinatural landscapes is analyzed. Methods: Analysis of the state of the phytocenosis of the reclaimed spoil heap with the determination of the water permeability of the spoil material. Results: It has been established that the productivity of phytocenoses on reclaimed spoil heaps of coal mines directly depends on the hydrological properties of the formed soils, and is more effective in areas where the process of soil formation is almost completed. Practical significance: It is shown that the most favorable hydrological conditions on the surface of the reclaimed colliery spoil heaps contribute to the formation of phytocenoses at the level of natural landscapes.

Assessing the watershed-scale effects of tillage management on surface runoff and sediment loss using a Curve Number-precipitation relationship based approach

Poor soil management limits the soil functions of water infiltration and storage and enhances water and soil losses. Adoption of improved soil management practices is thus vital to protecting agricultural soils amid recurring droughts and declining water availability. Although the benefits of adopting soil health promoting practices such as no-tillage (NT) have been extensively investigated at field scale, studies quantifying the watershed-scale impacts of such practices are lacking. This study aims to address this gap by quantifying soil and water conservation benefits of adopting NT over conventional tillage (CT) on all croplands in the Brushy Creek Watershed in the Texas Blackland Prairies using the Agricultural Policy/Environmental eXtender (APEX) model. Most hydrologic and water quality models often fall short in accurately simulating the effects of management practices since they are not capable of simulating changes in soil and hydrologic properties that result from changes in soil management. This study proposed a novel framework to translate field-scale rainfall and runoff relationships into a watershed-scale parameterization tool that can be used for any agricultural watershed where measured rainfall and runoff data are available. Curve Number–Precipitation (CN-P) relationships were first defined based on field observations of rainfall and runoff from paired CT and NT fields. The CT and NT APEX models were then trained to follow the defined CN-P relationships to reflect the associated changes in hydrologic properties. Changing management from CT to NT on all croplands in the study watershed (i.e., in 35% of the watershed area) resulted in a 25% (38 mm year−1) reduction in average annual runoff and a 57% (1.13 t ha -1year−1) reduction in average annual sediment loss at the outlet of the watershed. The reduction in sediment loss from individual subareas with NT management was found to be sensitive to subarea physical properties such as slope and channel depth to width ratio, but the reduction in runoff was not sensitive to those properties. Results from this study are useful to natural resource conservationists and watershed managers in effectively implementing improved soil management practices.

Two-phase reactive transport modeling of heterogeneous gas production in a low- and intermediate-level waste repository

Abstract. The widely proposed approach to dispose of low- and intermediate-level radioactive waste is to store it in a deep underground repository with multiple barriers. A typical gallery is filled with concrete containers accommodating cemented steel drums of waste. Inside a container, different gases may be produced by (bio)chemical reactions, which include pH-dependent anoxic corrosion of metals and the degradation of organic matter. Both reactions consume water and may lead to pressure buildup and transport of gas, both within and around the repository. In order to investigate the controlling factors of this gas production process, a coupled reactive transport model of component-based two-phase flow in the OpenGeoSys framework is adopted here. The numerical study of Huang et al. (2021) has shown that a realistic internal structure of a waste package, including the heterogeneous distribution of materials with different chemical and hydrological properties, and the exchange of mass at the boundaries are key factors that determine the evolution of the waste package. Based on the study of Huang et al. (2021), the geometric configuration of the model has been further extended to reflect the various conditions of a multi-container disposal in a gallery. In a two-dimensional setup several model scenarios have been designed and simulated to study the change in gas production rate over time in relation to water availability in various geological and waste storage setups. In this presentation, we show simulation results covering the geochemical evolution of a waste package over 500 years. It is found that the initial water content in the waste compartment only controls the gas production rate for the first 40 to 60 years. The early pressure buildup and gas release rates are largely controlled by several critical parameters, including the permeability of cement material and water availability at the boundary. The sensitivity of these parameters is currently being investigated in detail.

Hydrological Properties of Litter in Different Vegetation Types: Implications for Ecosystem Functioning

This study investigated the hydrological properties of litter in different vegetation cover types, including Eucalyptus sp. plantation, Agroforestry, and Restoration Forest. The research focused on evaluating litter accumulation, composition, water holding capacity, and effective water retention. The results revealed variations in litter accumulation among the stands, and especially Eucalyptus sp., which had a higher proportion of branches compared to leaves. The water holding capacity of the litter differed among the stands. Agroforest and Restoration Forest showed higher litter water capacities than Eucalyptus sp. The composition and decomposition stage of the litter fractions influenced their water retention capabilities, with leaves exhibiting superior water retention. In contrast, branches had lower water absorption due to their hydrophobic nature. Despite these differences, the effective water retention, which indicates the ability of litter to intercept precipitation, was similar among the stands. The findings highlight the importance of considering litter composition and species-specific characteristics in understanding the hydrological functions of litter. This knowledge contributes to effective conservation and management strategies for sustainable land use practices and water resource management. Further research is recommended to expand the study’s scope to include a wider range of forest types and natural field conditions, providing a more comprehensive understanding of litter hydrological functions and their implications for ecosystem processes.

Rewilding and the water cycle

AbstractRewilding is a radical approach to landscape conservation that has the potential to help mitigate flood risk and low flow stresses, but this remains largely unexplored. Here, we illustrate the nature of hydrological changes that rewilding can be expected to deliver through reducing or ceasing land management, natural vegetation regeneration, species (re)introductions, and changes to river networks. This includes major changes to above‐ and below‐ground vegetation structure (and hence interception, evapotranspiration, infiltration, and hydraulic roughness), soil hydrological properties, and the biophysical structure of river channels. The novel, complex, uncertain, and longer‐term nature of rewilding‐driven change generates some key challenges, and rewilding is currently relatively constrained in geographical extent. Significant changes to the water cycle that benefit people and nature are possible but there is an urgent need for improved understanding and prediction of rewilding trajectories and their hydrological effects, generation of the knowledge and tools to facilitate stakeholder engagement, and an extension of the geography of rewilding opportunities.This article is categorized under: Science of Water > Hydrological Processes Science of Water > Water Extremes Water and Life > Conservation, Management, and Awareness

Alternations of open and closed lakes in the Lower Aptian Codó Formation (Parnaíba Basin, Brazil)

Lakes can be classified as open, semi-closed, and closed based on the balance between accommodation space and sediment–water fill. Different lake types can coexist in adjacent basins and rapidly change throughout time from one type to another. Understanding the processes that result from shifts in a lake's hydrological properties can be challenging, as well as characterizing its sedimentary products. The Aptian Codó Formation, in the Parnaíba Basin, north–northeast Brazil, contains in its record a complex facies succession deposited in a continental lacustrine system. In order to better understand the depositional aspects of different lake types, we characterized the lower portion of the Codó Formation using a multi-proxy approach. We combined litho- and microfacies analysis, ichnology, bulk chemical data, mineralogy, isotopic geochemistry, and organic matter analysis in the recently drilled, fully recovered borehole, 2-CO-1-MA. We defined eight lithofacies: bioturbated siltstones, dark gray mudstones, laminites, stratiform and domal stromatolites, heterolites rich in ostracods and organic muddy, and anhydrite and gypsum rocks. The isotopic data and the palynofacies analysis pointed out the existence of restricted conditions (TOC up to 19.6 wt%) with intermittent connections with seawater. Integrating all techniques, we interpreted five depositional stages: expanded lake, brackish ephemeral lake, perennial shallow lake, evaporitic sabkha, and stratified lake. These stages were influenced by the relation between inflow and evaporation rate, which were the main controls on sedimentation in the lacustrine-sabkha system studied. Our findings provide a detailed description and interpretation of the paleoenvironmental conditions related to the alternation from open to closed lakes, combining sedimentological, geochemical, and palynological characteristics of an inland lake system.

The Development of Ungauged-Catchment Integrated-Similarity Unit Hydrograph to Estimate Inflow of Wonogiri Reservoir

The Wonogiri Reservoir is a multipurpose reservoir at the Upper Bengawan Solo Watershed, primarily designed to serve as a flood control system. However, there is no accurate estimation of the inflow into the reservoir due to the limited availability of hydrological stations. Observations showed only four out of ten unit hydrographs of the Wonogiri Reservoir watershed. Therefore, this study was conducted to apply an integrated similarity-based approach for designing unit hydrographs in ungauged catchments. The process involved evaluating the integrated similarity between pairs of gauged-ungauged catchments using hydrologic and physical property parameters. This led to the selection of the donor or gauged catchment with the highest similarity score to develop the unit hydrograph for the ungauged catchments. The developed UHs were further applied to estimate the reservoir inflow for the December 25, 2007, flood event. The results showed that the computed peak discharge was 10.9% lower than a previous study. Subsequently, the HEC-HMS simulation model was used to project the updated design flood hydrographs to the reservoir. The design rainfall was derived from automatic rainfall recorder (ARR) and PERSIANN satellite-based data. The ARR data showed that the extreme rainfall duration was 5 hours while satellite data indicated 6 hours. The application of the ARR 5-hour duration to the updated flood hydrographs led to a peak discharge of 5123 m3 s-1, 7041 m3 s-1, and 10,370 m3 s-1 for the 60-year, 500-year, and PMF floods respectively in line with the flood design criteria of Wonogiri Reservoir. These estimates were observed to be significantly higher than the 1982 design floods which were 4000 m3 s-1, 5100 m3 s-1, and 9600 m3 s-1 respectively. This updated flood control design was important to renew the operation rule of the Wonogiri reservoir during flood periods.

Long‐term reconstruction of energy fluxes in an alpine river: Effects of flow regulation and restoration

AbstractFlow regulation of montane and alpine headwater streams can fundamentally alter food web structure and energy flows through changes in productivity, resource availability, and community assembly. Dam flow‐release schemes can be used to mitigate the environmental impacts of flow regulation via environmental flows, which can increase discharge variability and other ecologically important hydrological properties. In particular, managed floods can reintroduce disturbance to the system and stimulate the reactivation of physical habitat dynamics. However, how managed floods might restore ecosystem processes is virtually unknown. In this study, we examined patterns in potential energy fluxes before, during and after a long‐term experimental flood program on the river Spöl, a regulated alpine River in southeast Switzerland. We used benthic samples collected during long‐term monitoring and stable isotope analysis (δ13C and δ15N) of macroinvertebrates and their potential food sources to reconstruct secondary production, and potential energy fluxes, over a 20‐year study period. The experimental floods did not alter the relative importance of basal resources but resulted in a considerable decline in secondary production, which remained low after the discontinuation of the floods. Our data suggest that a lack of recolonization by mosses following the discontinuation of the experimental flood program on the river Spöl may have driven patterns in energy fluxes by limiting macroinvertebrates using mosses for habitat. The effects of environmental flows on energy flows in this system thus depend on flood disturbance and the environmental context following the discontinuation of floods.