Alluvial Water Research Articles

A hydrological framework for persistent pools along non-perennial rivers

Abstract. Persistent surface water pools along non-perennial rivers represent an important water resource for plants, animals, and humans. While ecological studies of these features are not uncommon, these are rarely accompanied by a rigorous examination of the hydrological and hydrogeological characteristics that create or support persistent river pools. Here we present an overarching framework for understanding the hydrology of persistent pools. Perched surface water, alluvial water throughflow, and groundwater discharge are the key hydraulic mechanisms that control the persistence of pools along river channels. Groundwater discharge can be further categorized into that controlled by a geological contact or barrier and discharge controlled by topography. Emphasis is put on clearly defining throughflow of alluvial water and the different drivers of groundwater discharge. The suite of regional-scale and pool-scale diagnostic tools available for elucidating these hydraulic mechanisms are summarized and critiqued. Water fluxes to pools supported by throughflow alluvial and groundwater discharge can vary spatially and temporally, and quantitatively resolving pool water balance components is commonly non-trivial. This framework allows for the evaluation of the susceptibility of persistent pools along river channels to changes in climate or groundwater withdrawals. Finally, we demonstrate the application of this framework using a suite of the available tools to conduct a regional and pool-scale assessment of the hydrology of persistent river pools in the Hamersley Basin of north-western Australia.

Increasing contribution of alluvial groundwater to riparian cottonwood forest water use through warm and dry summers

In semi-arid regions, riparian forests access alluvial groundwater to supplement the limited local precipitation. Understanding the sensitivity of riparian forests to variations in weather and climate, and water resources management is essential for guiding riparian conservation measures, especially on rivers impacted by dams and water withdrawal. We anticipated a seasonal trade-off in ecosystem water sources, with increasing relative groundwater use through the summer to compensate for the reduced availability of the shallow soil moisture. To test this hypothesis, we assessed the temporal patterns of alluvial groundwater uptake by a riparian cottonwood (Populus species) forest along a regulated river in southern Alberta, Canada over a three-year interval with relatively warm and dry weather, and low river flows. In support of our hypothesis, groundwater evapotranspiration, as calculated from diurnal fluctuations in the alluvial water table, displayed relative seasonal consistency until the autumnal leaf senescence period. In contrast, the ecosystem-scale evapotranspiration, measured by eddy covariance, gradually receded through the summer as precipitation inputs that fed the shallow soil layers became limited. The consistent uptake rate of alluvial groundwater by cottonwoods enables riparian forests to maintain high rates of water use and productivity in this semi-arid prairie region. We conclude the consistent groundwater use through the warm and dry summer reflected: (1) perennial river flow that replenished the floodplain aquifer; (2) adaptations of cottonwoods to the riparian hydrology and the semi-arid climate; and (3) environmental flow operations that maintained the minimum river and alluvial groundwater levels. Our study provides information on the riparian forest water sources and water use patterns that could help water managers effectively regulate river flows to support healthy downstream riparian ecosystems.

Carp Breeding in the Carpathian Basin with a Sustainable Utilization of Renewable Natural Resources.

In the Central European region, there is a long tradition of breeding fish in artificially constructed ponds. As the area belongs to the temperate zone, farmed fish need to survive cold winter periods. Common carp (Cyprinus carpio L.), which is an omnivorous, bioturbating species, is well adapted to warm and cold periods and the alluvial water environment. Since the Middle Ages, a large scale, efficient carp farming methodology has been developed in the region, where production is based on natural resources (protein and fatty acid sources) of renewable water ecosystems. This summary aims to present this well-developed breedi:ng method through discussing aspects of hydrobiology and energy transfer through the food chain as well. Capabilities and effects of agro-technical treatments such as liming and organic manuring, zooplankton management and possible supplementary feedings are also reviewed. Analysing chemical processes of waters uncovers that biological production has no carbon footprint; no carbon dioxide is released into the atmosphere. In contrast, gaseous carbon dioxide diffuses into pond water containing calcium and/or magnesium, then it accumulates in algae production and, through energy migration to upper trophic levels, increases carp production. Thus, it can be declared that pond-farmed carp provides an environmentally friendly, delicious meat among products of animal origin.

Robustness of DRASTIC Method for Groundwater Vulnerability Case of Wadi Nil Aquifer in Jijel, NE Algeria

DOI:10.17014/ijog.9.2.229-246The alluvial water table of Wadi Nil is characterized by an abundance of groundwater, attributed to the high rainfall (1,000 mm/yr on average) of the region, the good permeability of its aquifer (10-3 to 10-4 m/s), and its significant thickness (35 to 100 m). Its waters are used for drinking water as well as for irrigation. In recent years (2000-2020), significant growth in terms of urban, agricultural, and industrial activities has developed on the plain, and has generated a significant amount of waste and effluents. In order to protect the groundwater resource, a map of the vulnerability of the water table to pollution, intended to guide public policies, has been drawn up. The DRASTIC method is a method chosen for the creation of this map, in view of its efficiency and reliability. The results obtained show that the groundwater consists of three zones: the first zone - of moderate vulnerability - is located in the outcrop areas of the marl formations (central part of the plain); the second - of high vulnerability - occupies most of the plain, composed mainly of the wadi alluvial formations; and finally the third - of very high vulnerability - is located in the downstream part of the groundwater, where the aquifer formations are sandy. The statistical analyses and sensitivity analysis of DRASTIC parameters highlight the importance of the parameters «water depth, recharge, and impact of the vadose zone» in the elaboration of the vulnerability map of the studied area, and show that the approach is relatively robust. Nevertheless, if the “water depth” and “recharge” parameters can be constrained by field measurements, the “impact of vadose zone” parameter appears to be the most delicate, because it is both sensitive and associated with uncertainties

Contribution of isotopic techniques to the knowledge of the aquiferous system of the great Sebkha of Oran

In the Great Sebkha Basin of Oran, water flows, both surface and subterranean, originate on the slopes and converge toward the discharging area of the salt Lake Great Sebkha of Oran (≈ 80 m above sea level). Isotopic water tracing of 2H, 18O, 14C, and 13C was carried out on the main aquifer formations to clarify the phenomena of evaporation, dissolution, mixing of different water bodies, and their residence time in the aquifer system. The data concern: the salt Lake of the Great Sebkha of Oran, the Quaternary alluvial water table of the periphery, the limestone Miocene, the Brédéah pumping station (whose waters are polluted by brackish water intrusions), deepwater tabler table of the Mio-Pliocene complex of the Plain of Maflak, the Pliocene of the Plain of Tameira, and the Thermal Complex of Hammam Bou Hadjar. The d18O levels range from −9.61 to + 4.8 ‰ V-SMOW at the salt Lake of Great Sebkha of Oran. The 2H contents range from −70 to 20. Minimum values characterize run off from the northern slopes of the Tessala. The 13C contents of dissolved total inorganic carbon (TDI) measured ranged from −10.92 to −3.9 ‰ vs PDB. The activities of the 14C are divided between 2 and 51 PMC. The highest activity in 14C (≈50 PMC) is measured on samples taken from the Miocene limestones of Djebel Murdjadjo.

О задачах исследований водных ресурсов Оренбуржья и сопредельных районов

The actual problem of the regions of the Southern Cis-Urals is the provision of population with drinking water. The problem is sharpened with increase of water consumption by population and industry. The analysis of the situation, carried out by the author on the example of the Orenburg urban agglomeration, indicates the possibility of solving this problem by replenishing the water reserves of the existing alluvial water intakes due to the accumulation of a part of the flood runoff. When the water level in the river rises, the level of groundwater rises and water inflows to water wells grow. When water is filtered through alluvium, it self-purifies from pollutants. Replenishing groundwater reserves during floods increases the resources and the quality of drinking water.

An Estimation of Annual Sediment Load for Egyptian Irrigation Canals.(Dept.C)

Erosion, transport, and deposition processes in alluvial channel are considered one of the complex phenomena due to the limited knowledge in the theory of interaction between water and sediment flow, and in predicting the behaviour of alluvial water courses. In the last thirty years although experience in sediment transport in both practice and theory as well as the increasing capacity of digital computers and the numerical techniques have provided a substantial aid in this field, but the mechanics of sediment transportation is still considerably far from being satisfactory. Four conventional bed load formulae have been applied to some selected Egyptian irrigation canals. Located in the Delta region. Limitations of each formula have been discussed, and the most appropriate formula has been used for an estimation of the annual bed load for these canals.

Research on drinking-groundwater source safety management based on numerical simulation

A drinking-groundwater source protection technology system based on a three-dimensional finite-difference groundwater model was constructed and applied to the safe management of drinking groundwater in the first terrace of Fujiang River. In the study area, the main type of groundwater is the quaternary systemic alluvial deposit loose rock pore water and the aquifer thickness varies between 20 and 35 m. Groundwater is the main source of water and is used for various purposes through two exploitation wells. The water volumes of 1# exploitation well (1#) and 2# exploitation well (2#) are 10,000 m3/day and 5000 m3/day, respectively. An analysis of 22 indicators from 11 groundwater samples showed that a higher concentration of chemical-oxygen-demand (CODMn) and ammonia–nitrogen (NH3–N), and they had a high correlation with most of the other water-quality factors. Therefore, CODMn and NH3–N were selected as indicator factors for model calibration and prediction. Twenty-two hydraulic head observation wells were used for flow-model calibration. The flow model indicated that a drop funnel formed with a maximum depth of 12 m, and the particle-capture zone in the original downstream direction of the south side extended to 1100 m because of groundwater exploitation. The solute-transport model showed that industrial pollution sources were the main factors that led to a deterioration of water quality. To analyze the necessity and effectiveness of remediation measures for the safety of drinking-water sources, two scenarios were considered to predict the concentration of NH3-N and CODMn in groundwater exploitation wells over 20 years. Scenario I, which considered that current conditions were maintained, predicted that the NH3-N would exceed the drinking-water quality standard of 0.5 mg/L after 16 years. Scenario II, in which industrial sewage treatment plants were installed outside the particle-trapped zone of the exploitation wells and strict anti-seepage measures were implemented, predicted that the peak concentrations of NH3-N and CODMn in the exploitation wells would be 0.26 mg/L and 1.33 mg/L, respectively, after 3 years of model operation. This study provides a theoretical basis for drinking-groundwater source protection that can be applied to safety management practices.

Elucidating fecal pollution patterns in alluvial water resources by linking standard fecal indicator bacteria to river connectivity and genetic microbial source tracking

A novel concept for fecal pollution analysis was applied at alluvial water resources to substantially extend the information provided by fecal indicator bacteria (FIB). FIB data were linked to river connectivity and genetic microbial source tracking (MST). The concept was demonstrated at the Danube River and its associated backwater area downstream of the city of Vienna, using a comprehensive 3-year data set (10 selected sites, n = 317 samples). Enumeration of Escherichia coli (ISO 16649-2), intestinal enterococci (ISO 7899-2) and Clostridium perfringens (ISO 14189) revealed a patchy distribution for the investigation area. Based on these parameters alone a clear interpretation of the observed fecal contamination patterns was not possible. Comparison of FIB concentrations to river connectivity allowed defining sites with dominating versus rare fecal pollution influence from the River Danube. A strong connectivity gradient at the selected backwater sites became obvious by 2D hydrodynamic surface water modeling, ranging from 278 days (25%) down to 5 days (<1%) of hydraulic connectivity to the River Danube within the 3-year study period. Human sewage pollution could be identified as the dominating fecal source at the highly connected sites by adding information from MST analysis. In contrast, animal fecal pollution proofed to be dominating in areas with low river connectivity. The selection of genetic MST markers was focusing on potentially important pollution sources in the backwater area, using human (BacHum, HF183II), ruminant (BacR) and pig (Pig2Bac) -associated quantitative PCR assays. The presented approach is assumed to be useful to characterize alluvial water resources for water safety management throughout the globe, by allocating fecal pollution to autochthonous, allochthonous, human or animal contamination components. The established river connectivity metric is not limited to bacterial fecal pollution, but can be applied to any type of chemical and microbiological contamination.

Neotectonic Activity Using Geomorphological Features in the Iraqi Kurdistan Region

Iraqi Kurdistan Region is located in the northeastern part of the Arabian Plate which is colliding with the Eurasian (Iranian) Plate and is located within the Zagros Foreland Basin. This collision, which is still active with convergent type of tectonic boundary, has caused deformation of the rocks in the Zagros Foreland Basin with different intensities. The deformation intensity decreases southwest wards since the exerted stresses from the collision is in a NE–SW direction. Depending on the deformation intensity and many other factors, the tectonic framework of the region which is part of the main tectonic frame of Iraq is divided into three main tectonic units among them only two units are within Kurdistan Region. The two zones are from NE–SW direction: (1) Shalair Terrane, and (2) Outer Platform. In the current study, evidences about Neotectonic activities are presented from different parts of Kurdistan Region depending on different geomorphological and structural features. Among those features are: abnormal trends of valleys, dislocated and dissected alluvial fans, regional lineaments, water and wind gaps, faulted rocks of Pliocene–Pleistocene age, active faults. The Neotectonic evidences were recognized using satellite images and the existing Neotectonic data, and validated in the field.

Diel cycles of δ13CDIC and ecosystem metabolism in ephemeral dryland streams

Streams in hot, arid environments often exist as a series of isolated pools along main channels. During these periods, shallow alluvial through flow may strongly influence key ecological processes within pools. We measured diel changes in δ13C values of dissolved inorganic carbon (DIC) and dissolved oxygen (DO) in two pools of ephemeral, dryland streams. We quantified alluvial water connectivity through stable isotope analysis (δ18O and δ2H) of pool and alluvial water. We also estimated gross primary productivity (GPP) and ecosystem respiration (ER) rates across a wider set of pools in both streams. δ13CDIC values displayed regular diel cycles, where both pools displayed small but similar daily amplitude (0.7–0.9‰) despite contrasting amplitudes of change in DO (0.8 mg L−1 vs. 2.8 mg L−1) and contrasting alluvial water connectivity (connected vs. disconnected). Water temperature was the strongest predictor of both δ13CDIC values and rates of change in δ13CDIC across both pools. Across both streams, all pools were net heterotrophic. GPP (0.35–1.73 g O2 m−2 d−1) and ER (0.49–2.64 g O2 m−2 d−1) rates were linked to aquatic vegetation cover. The disconnect between diurnal amplitudes of δ13C values and DO concentrations thus suggests that ecological drivers of gas exchange became increasingly localised as pools contracted.

К МЕТОДИКЕ И МЕТОДОЛОГИИ ГИДРОГЕОЛОГИЧЕСКИХ ИССЛЕДОВАНИЙ ТЕРРИТОРИИ ЮЖНОГО ПРЕДУРАЛЬЯ

Providing the population with drinking water is an urgent problem in the areas of the South Urals. It escalates during the dry periods of the summer low water. An analysis of the situation, performed by the author on the example of the Orenburg agglomeration, indicates the possibility of solving this problem by recovery of the water reserves of the existing alluvial water intakes by the accumulation of part of the flood flow. When the water level rises in the river, the groundwater level rises and water inflows to the water wells increase. When water filtering through alluvium they clean themselves from pollutants. Therefore, during groundwater recovery process in the flood period, resources increase and the quality of drinking water improves.

Hydrogeological Assessments of Impacts of Irrigation on Alluvial Water Table of Delta of Senegal River

Building dams on the Senegal River has facilitated the development of irrigated farming in Delta of Senegal River. However, this practice is threatened by the increasing degradation of soils mainly caused by salinization. The main cause of this problem is the presence of a salty aquifer at a low depth. Nevertheless, the characteristics and functioning of this aquifer are not well known. The main objective of this study, funded by Wallonie-Brussels International, is a contribution to the characterization of the hydrodynamic functioning, the hydro geochemistry of the aquifer and to identify the impact on agricultural waters. A two-step methodology has been developed: Firstly, a regional survey has been performed in the whole delta; secondly an irrigation plot has been monitored to have a detailed description of the groundwater dynamic and of the transport of salt under irrigation. Results of the regional survey show (1) the main factors that explain the fluctuation of the groundwater level are the artificial high water levels in the River, rice growing and to a lesser extent precipitation and (2) the high salt concentration in the upper aquifer. The monitoring of the Ndelle rice growing area (30 km to the North-East of Saint-Louis) has allowed calculating water and salt budgets at the scale of the irrigation plot. The influence of the irrigation on the groundwater levels has also been studied.

Dating of alluvial sediments from borehole at the lower course of the Sava river and indications of the connection between their genesis and climate changes in the Pleistocene

This paper analyses the way in which Pleistocene climate change and glaciations in Dinaric Mountains was reflected in the deposition of alluvial sediments in the Sava river Valley, using a case study of Belgrade Groundwater Source (BGS), the largest and most downstream alluvial water supply source along the Sava river. A stratigraphic analysis of the Quaternary sediments from two boreholes on this site, based on sediment dating, lithological members identification, grain size distribution analysis was performed. Comparison with the results of dating of the moraines and glacial outwash, the remnants of glaciations in Dinaric mountains of Montenegro, by Hughes et al. and Adamson et al. showed a good match, as the dating of the last four sedimentation cycles yielded the 13.2 ka (start of MIS1), 80.9 ka (MIS 5a), 137.5 (end of MIS6 or start of MIS5) and 193.4 ka (MIS 7) ages, corresponding to MIS1, MIS 5a, end of MIS6 and start of MIS5, and MIS7 stages for glacial outwash, and to MIS2, MIS5b and MIS5d, end of MIS6 and start of MIS5, and MIS8 stages for the moraines. The ages of older cycles were presented as a hypothesis based on aforementioned succession of ages.

Assessment of the quality and irrigation purpose suitability of alluvial water in Erfoud, Morocco

Abstract Dry areas are especially exposed to the risk of water shortages and elevated mineralization. High water salinity, caused by low precipitation, high evaporation and human impact, usually strongly limits the use of the water for irrigation. The aim of the study was to assess the quality and irrigation purpose suitability of alluvial water in the Erfoud oasis, Morocco. The samples of water were collected from 20 wells in June 2017. We observed excessive concentrations of many parameters i.a.: NO3, Cd, Ni, Na, NH4, Cl, SO4, Fe, Cr. To determine the possibility to use the water for irrigation purposes, the Sodium Adsorption Ratio (SAR), sodium percentage (%Na), permeability index (PI), Kelly’s ratio (KR), magnesium hazards (MH) and electrical conductivity (EC) were assessed. The values of KR and MH qualified the waters as unsuitable for irrigation purposes. The observed %Na indicates that the groundwater is permissible for irrigation purposes, and permeability index, that it is of moderate quality. However, water classification using the SAR vs EC diagram confirms its high and very high alkali and salinity hazard. The mean EC value of the water was 9.5 mS cm−1.

Hydroclimatic drivers of the growth of riparian cottonwoods at the prairie margin: River flows, river regulation and the Pacific Decadal Oscillation

Cottonwoods, riparian poplars, are facultative phreatophytes and can obtain water from shallow soil moisture originating from rainfall, or from the deeper capillary fringe above the alluvial water table that is recharged by river water infiltration. The correspondence between cottonwood growth and river flows should reveal the dependency upon alluvial groundwater and subsequently, the vulnerability to reduced river flows. To explore this association, we analyzed historic growth patterns of plains cottonwoods (Populus deltoides) along the Red Deer River (RDR), which is at the northwestern limit of the North American Great Plains. We developed chronologies of yearly radial increments (RI) and basal area increments (BAI) and explored correspondences with the environmental records from the past century. In this semi-arid region, the RI or BAI were not correlated with local precipitation while negative correlation with growth season temperature (T) (r = −0.37, p < 0.01) could reflect reduced growth with hot summers. There was correlation between growth and annual river discharge (Q, and particularly log Q that approximates river stage) and this increased with two year averaging (r = 0.51, p < 0.01), reflecting carry-over in the watershed hydrology and in the ecophysiological response. There was correspondence with the Pacific Decadal Oscillation index (PDO, r = −0.45, p < 0.01), which provides multi-decade transitions that influence Rocky Mountain headwater precipitation and other weather characteristics, and river flows. The combination of Q, PDO and T provided the strongest multiple regression model, accounting for 44% of the historic growth variation (52% correspondence for 1953–2013). The RDR was dammed in 1983, enabling winter flow augmentation, but summer flows were sustained and cottonwood growth and the streamflow correspondence persisted. This indicates that it is the pattern of dam operation and not damming per se that determines the fate of established riparian cottonwoods downstream. This study revealed that these cottonwoods are phreatophytic and dependent upon alluvial groundwater that is recharged from the river. This provides a research strategy to determine whether riparian woodlands along other regulated rivers are similarly groundwater-dependent and could be vulnerable to river flow reductions from excessive water withdrawal for irrigation or other uses, or with climate change.

Neutron and photon activation analyses in geochemical characterization of Libyan Desert Glass

Geochemical characterization of nine samples of Libyan Desert Glass (LDG) based on assay of more than forty elements by instrumental neutron and photon activation analyses has pointed to quartz sand cemented by aluminosilicates and Fe, Ti oxides as LDG parent materials. Contamination by extraterrestrial material has not been evidenced in studied LDG samples, but depletion of volatile elements indicating their evaporation during the impact process was noticed. Authors support the common concept of LDG formation by an impact into Cretaceous Nubian sandstones, derived from Proterozoic crystalline basement and possibly weathered and redeposited from alluvial or shallow water marine environments.

Flow reconstructions in the Upper Missouri River Basin using riparian tree rings

River flow reconstructions are typically developed using tree rings from montane conifers that cannot reflect flow regulation or hydrologic inputs from the lower portions of a watershed. Incorporating lowland riparian trees may improve the accuracy of flow reconstructions when these trees are physically linked to the alluvial water table. We used riparian plains cottonwoods (Populus deltoides, ssp. monilifera) to reconstruct discharge for three neighboring rivers in the Upper Missouri River Basin: the Yellowstone (n = 389 tree cores), Powder (n = 408), and Little Missouri Rivers (n = 643). We used the Regional Curve Standardization approach to reconstruct log-transformed discharge over the four months in early summer that most highly correlated to tree ring growth. The reconstructions explained at least 57% of the variance in historical discharge and extended back to 1742, 1729 and 1643. These are the first flow reconstructions for the Lower Yellowstone and Powder Rivers, and they are the furthest downstream among Rocky Mountain rivers in the Missouri River Basin. Although mostly free-flowing, the Yellowstone and Powder Rivers experienced a shift from early- to late-summer flows within the last century. This shift is concurrent with increasing irrigation and reservoir storage, and it corresponds to decreased cottonwood growth. Low-frequency flow patterns revealed wet conditions from 1870-1980, a period that includes the majority of the historical record. The 1816-1823 and 1861-1865 droughts were more severe than any recorded, revealing that drought risks are underestimated when using the instrumental record alone. This article is protected by copyright. All rights reserved.

Update of the Surat Underground Water Impact Report

The production of coal seam gas (CSG) involves the pumping of large volumes of groundwater to lower water pressure in coal seams. This has the potential to affect groundwater resources in the coal-bearing formations and in adjacent aquifers connected to the coal formations. The formations that are the target for CSG development in the Surat Basin in Queensland are part of the Great Artesian Basin multi-layered aquifer system and also underlie important alluvial water resources. There are multiple major CSG projects being developed in the area. Queensland has a regulatory framework to manage the impact of CSG water extraction on groundwater resources that includes cumulative management arrangements for areas of intensive development, where the groundwater impacts of multiple projects overlap. In a declared Cumulative Management Area, the Office of Groundwater Impact Assessment (OGIA) carries out a regional assessment of impacts of CSG water extraction, specifies an integrated regional water monitoring network, and assigns responsibilities to individual CSG companies to implement individual parts of the water monitoring network and other management actions. OGIA sets out the results in an underground water impact report (UWIR), which on approval becomes a statutory instrument. OGIA is an independent entity fully funded by a levy on petroleum tenure holders. The first Surat UWIR was approved in 2012. In early 2016, OGIA revised the Surat UWIR using a new regional groundwater flow model that incorporates updated knowledge of the groundwater flow system. The key content of the revised Surat UWIR is presented.

Algal Bio-Indication in Assessment of Hydrological Impact on Ecosystem in Wetlands of “Slavyansky Resort”

Abstract Algal bio-indication is commonly used in water quality assessment but can also help in assessing the impact of hydrology on freshwater wetland ecosystems.We identified 350 species and infraspecific taxa of algae from nine taxonomic divisions (Cyanoprokaryota, Chrysophyta, Euglenophyta,Dinophyta,Xanthophyta,Cryptophyta,Bacillariophyta,Chlorophyta,Charophyta) in 121 phytoplankton samples collected between 2007-2013 from seven lakes in the wetlands of the Regional Landscape Park “Slavyansky Resort”, Ukraine. The algal species richness and phytoplankton biomass decreased as water salinity increased. In turn the water salinity was influenced by the inflow of groundwater, karst fracture and by the alluvial water tributaries of a paleoriver that affects the formation processes of lake-spring sulphide mud from the resort, which is often used for therapeutic purposes.