Marine Intrusion Research Articles

Doppler-Lidar Evaluation of HRRR-Model Skill at Simulating Summertime Wind Regimes in the Columbia River Basin during WFIP2

AbstractComplex-terrain locations often have repeatable near-surface wind patterns, such as synoptic gap flows and local thermally forced flows. An example is the Columbia River Valley in east-central Oregon-Washington, a significant wind-energy-generation region and the site of the Second Wind-Forecast Improvement Project (WFIP2). Data from three Doppler lidars deployed during WFIP2 define and characterize summertime wind regimes and their large-scale contexts, and provide insight into NWP model errors by examining differences in the ability of a model [NOAA’s High-Resolution Rapid-Refresh (HRRR-version1)] to forecast wind-speed profiles for different regimes. Seven regimes were identified based on daily time series of the lidar-measured rotor-layer winds, which then suggested two broad categories. First, in three regimes the primary dynamic forcing was the large-scale pressure gradient. Second, in two regimes the dominant forcing was the diurnal heating-cooling cycle (regional sea-breeze-type dynamics), including the marine intrusion previously described, which generates strong nocturnal winds over the region. The other two included a hybrid regime and a non-conforming regime. For the large-scale pressure-gradient regimes, HRRR had wind-speed biases of ~1 m s−1 and RMSEs of 2-3 m s−1. Errors were much larger for the thermally forced regimes, owing to the premature demise of the strong nocturnal flow in HRRR. Thus, the more dominant the role of surface heating in generating the flow, the larger the errors. Major errors could result from surface heating of the atmosphere, boundary-layer responses to that heating, and associated terrain interactions. Measurement/modeling research programs should be aimed at determining which modeled processes produce the largest errors, so those processes can be improved and errors reduced.

Public Participation for Integrated Groundwater Management: The Case of Maneadero Valley, Baja California, Mexico

There is a controversy in groundwater management: some people argue that public participation has decreased efficiency in decision-making, while others believe this process is not executed effectively. Questions about whether public participation results from the context involving influential people, the rules, or the way participation mechanisms were designed need examination. In this study, opportunities, barriers, and challenges of public participation were analyzed in the management of a coastal aquifer affected by marine intrusion in the Maneadero Valley, México. Mixed methods were implemented, involving 28 interviews with key actors and 50 surveys conducted during 2014 and 2017 with groundwater users. Results show that public participation is mainly determined by power differences, lack of continuity in the participatory processes, and the design of the participation mechanisms. State actors have greater decision-making power in integrated groundwater management. In contrast, groundwater users have limited participation in the process of making proposals, and their participation is generally passive. There are limitations to broad, informed, and responsible public participation: examples of these limitations include different levels of information, inappropriate institutional arrangements, failure to disseminate scientific information, lack of spaces to exercise public participation, and absence of political will. Hence, to improve Maneadero aquifer management, it is necessary to decentralize decision-making, integrate technical and non-technical knowledge, generate scientific evidence about water availability, and give a prominent role to stakeholders and users from the initial stages. In addition, internalization and water culture are required. These results can help to guide integrated groundwater management in other arid regions.

Species-specific traits and the environment drive ichthyoplankton fluxes between an intermittently closed-open lagoon and adjacent coastal waters

This study evaluated the connectivity between an intermittently closed-open lagoon (LR) and adjacent coastal waters (CW), and the influence of that connection on ichthyoplankton assemblages. We performed field surveys along a year in LR and CW to capture different sandbar states (open/closed) and lagoon-sea connectivity processes (e.g. lagoon discharges, marine intrusion, overwashing). Results showed differences in environmental conditions and ichthyoplankton communities between LR and CW, and also evidenced different mechanisms of exchange of water and ichthyoplankton. At least three estuarine species were found to spawn and use LR as a nursery ground. Larval stages of six marine species were found at CW. Environmental factors (e.g. wind and runoff) and species-specific traits (e.g. life cycle strategy, spawning season) determined ichthyoplankton exchange vs. retention. Marine estuarine-related species entered LR mostly during summer-autumn, at their peak abundance in CW. Sandbar closure did not impede the entrance of these species. Overwashing events (closed bar) and light onshore winds during the open-sandbar period were the most important process that promoted the transport of these larvae into LR. Conversely, there was no evidence of entrance of marine estuarine-independent larvae to LR. Eggs and larvae of estuarine species that spawned within LR were effectively retained there, except when heavy rains led to severe lagoon discharges. Similarly, unusual strong onshore winds advected eggs from CW to LR, possibly reducing their survival. Generally, eggs were more vulnerable to drift than larvae. Many of the estuarine larvae that drifted out of the lagoon seemed to survive, suggesting a loss of individuals from the lagoon population but a potential contribution to the genetic flux among coastal populations.

From a large basin to a small lake: Siliceous microfossils stratigraphy of the isolation basins on Big Solovetskiy Island (the White Sea, NW Russia) and its implication for paleoreconstructions

This paper discusses the results of siliceous microfossils studies performed in a “staircase” of four isolation basins (33.7 m–2.9 m a.s.l.) on Big Solovetskiy Island (Solovki Archipelago, the White Sea). Diatoms were used as a primary group for paleoinferences, while chrysophyte cysts and sponge spicules also demonstrated high indicative potential. In all study lakes, the siliceous microfossils stratigraphy revealed three main stages of their evolution, i.e. large-basin, transitional and small-lake stages, each characterized by certain composition of the diatom assemblages and floristic diversity, relative abundances of chrysophyte cysts and sponge spicules, and siliceous microfossils concentrations. In the uppermost lake, glaciolacustrine environments unfavorable for aquatic biota existed during the large-basin stage. The proglacial lake stage terminated prior to ca. 10.4 cal ka BP, followed by a (semi)terrestrial episode before the transition to small-lake environments. In the other three lakes, marine environments were inferred at the earlier stage, characterized by the predominance of marine and brackish-marine diatoms, increased proportions of sponge spicules and low “cysts to diatoms” ratio. At the transitional marine-freshwater stage, mass growth of small fragilarioid diatoms and decreased abundances of spicules indicated unstable environments, while increased proportions of cysts pointed to progressive freshening of the basins. The duration of the marine-freshwater transition expectedly prolonged from ca. 200 yr in the upper basin (16.6 m a.s.l) to ca. 500 yr in the lowermost lake (2.9 m a.s.l.). The isolation from the sea took place between ca. 6.3 and 1.4 cal ka BP. At the small-lake stage, siliceous microfossils stratigraphies reflected local specifics of the basins and their catchments. We argue that besides traditionally used diatom data, relative and absolute abundances of siliceous microfossils also possess high indicative value for isolation basin studies. Our study demonstrated that marine waters on Big Solovetskiy Island never reached ca. 34 m a.s.l. during the Holocene, unlike the western coast of the Onega Bay where the Preboreal marine intrusion was recorded even at higher elevated localities. Different rates and amplitudes of shoreline displacement are thus suggested for the inner and outer parts of the Onega Bay. During the mid-Holocene Tapes transgression, before ca. 6.3 cal ka BP, the relative sea level on Big Solovetskiy Island exceeded 17 m a.s.l. The average estimated rates of the shoreline retreat during the second half of the Holocene gradually decreased from 0.28 cm year−1 to 0.2 cm year−1, indicating slowed isostatic uplift.

A geoelectric study of aquifers in the Essaouira coastal region, Morocco

A geophysical study carried out in the framework of the water resources recognition within the Essaouira coastal area (Morocco) enabled to outline the spatial distribution of the Plio-Pleistocene and Cretaceous formations. It helped to determine the thickness and extension of the main aquifer used for irrigation purpose. The overall aim of this study is to highlight the hydrogeological structures of Essaouira Basin.A total of 45 vertical electrical soundings (VES) were measured using linear Schlumberger array configuration with a maximum half-length (AB/2) of 1000 m along eight sections of 126 km total length. The number of soundings constituting the eight VES profiles depends on the topography and the obstacles encountered. The VES data were processed and interpreted. According to the thematic maps of the study area, the results indicate the existence of three types of VES with apparent resistivity values ranging from 44 to 320 Ω m. In relationship with wells and mechanical drillings existing in the area, the analysis of the results obtained made it possible to derive from the quantitative and qualitative maps the different apparent resistivity variations of the aquifer and aquiclude geological layers.The careful examination of these maps shows that the region around the Qsob River is of interest from a hydrogeological point of view. It is represented by a significant thick layer given the large extension of the resistive Plio-Pleistocene and Cretaceous formations. Geophysical studies show that this region is partially protected from marine intrusion given its location between Tidzi Diapir and hidden diapir from Essaouira which little plays the role of barrier. It is crossed by the Qsob River which lends itself as the main source of both these layers. The electrical discontinuities emerging from the superposition of the different maps, E-W, NE-SW and NNE-SSW oriented, are abundant and dense in the north Haha region (Qsob River). Generally, the salt water circulates along these discontinuities from West to North and Northeast which explains the abundance of low apparent resistivity values recorded northeastwards. This geophysical reconnaissance is the most important for water supply of this area affected by increasingly long periods of drought.

Groundwater quality of the alluvial and carbonate aquifers of Essaouira basin (Morocco)

The objective of this work was to determine the groundwater quality from semi-arid areas using physicochemical parameters, main dissolved constituents, boron, and selected metals and by taking as an example the Plio-Quaternary and Turonian aquifers of the Essaouira basin from western Morocco. The piezometric map shows that the groundwater flow is from the South-East to the North-West with a hydraulic gradient varying between 1.6 and 2.1%. Analytical results show that (1) groundwaters belong to the Na-Cl or Ca–Mg–Cl facies, (2) the groundwater mineralization is the result of the dissolution, base exchange, and marine intrusion processes. The concentrations of different metals in the water of the aquifers studied are relatively low and below the World Health Organization standards. The overall quality of the groundwaters hosted in the Plio-Quaternary and Turonian aquifers is medium to poor and not suitable for drinking. A suitable treatment should be considered before use.

Hydrogeochemical Characterization as a Tool to Recognize “Masked Geothermal Waters” in Bahía Concepción, Mexico

Geo-thermalism has been widely recognized on the Baja California Peninsula, especially during the last decade. The current research, carried out on Bahia Concepcion, evidences the existence of geothermal springs, which get recharged mainly by groundwater and seawater. The groundwater can be characterized as Na+-Cl− and Na+-HCO3− type, with a pH value close to neutrality. The slightly more acidic thermal sites presented temperatures between 32 °C and 59 °C at the surface. Based on the relationships of the Cl− and Br−, as well as the B/Cl−, and Br−/Cl− ratios, seawater was recognized as the main source of salinity. The spatial distribution is explained directly through marine intrusion, or via sprays and aerosols within the rainwater. Seawater ratios in thermal springs varied from 62% to 83%, corresponding mainly to shallow inflow, but seawater inputs into the deep thermal reservoir were also recognized. Temperatures in the geothermal deep reservoir were inferred from 114 to 209 °C, calculated through the SiO2 and Na+-K+ geothermometers. In addition to previously reported thermal sites at Bahía Concepción, and based on their elevated temperatures, two new sites were identified. Another five springs do not fulfill the commonly used definition, based on differential temperature, but show the typical hydrogeochemical signature of thermal water. A new approach to identify this low-temperature geothermal-influenced spring water by its hydrogeochemical composition is presented, for which the term “Masked Geothermal Waters” (MGW) is introduced. Our findings increase the area of the geothermal anomaly and, therefore, the potential of geothermal resources. The approach proposed in this research will also be useful to identify more MGW in other coastal areas.

Regional Hydrogeochemical Evolution of Groundwater in the Ring of Cenotes, Yucatán (Mexico): An Inverse Modelling Approach

The Ring of Cenotes (RC) extends along the edge of the Chicxulub crater, in the limestone platform of the Yucatan Peninsula (YP), where groundwater shows two preferential flow paths toward the coast near Celestun and Dzilam Bravo towns. The objectives of this study were to describe the regional hydrogeochemical evolution of the groundwater in the RC, and its association with the dissolution/precipitation of the minerals present along its pathway to the ocean. These objectives results were obtained by: (a) characterizing groundwater hydrogeochemistry; (b) calculating calcite, dolomite, and gypsum saturation indexes in the study area; and (c) developing a hydrogeochemical model using PHREEQC (U. S. Geological Survey) inverse modelling approach. The model predictions confirmed that there are two evolution pathways of the groundwater consistent with the preferential flow paths suggested in a previous regionalization of the RC. On the western path, where groundwater flows towards Celestun, marine intrusion influences the hydrogeochemical processes and represents a risk for the freshwater. On the eastern path, where groundwater flows toward Dzilam Bravo, rainfall has an important effect on the hydrogeochemical processes, evidenced by a higher concentration in sulfates during droughts than during rainy periods. Then, monitoring of marine intrusion and phases dissolution in the RC is highly recommended.

Seawater intrusion into coastal aquifers from semi-arid environments, Case of the alluvial aquifer of Essaouira basin (Morocco)

Marine intrusion phenomenon is the main phenomenon threatening the groundwater quality in coastal aquifers around the world. This phenomenon is generally caused by the overexploitation of aquifers, decline in the piezometric level and the rise in sea level under the climate change effect. There are several approaches to study and assess the marine intrusion phenomenon. For this study, the crossing of piezometric, hydrochemical and isotopic approaches was adopted to highlight the state of this phenomenon within the Plio-quaternary aquifer of the Essaouira basin. The couples (Na, Cl), (Ca, Mg), (Br, Cl), (δ2H, δ18O), (δ18O, Cl) were determined for 24 samples capturing the shallow aquifer of the Essaouira basin. The piezometric approach shows that negative piezometric levels are registered. The ionic ratios Br/Cl close to 1.5 and 1.7‰, Na/Cl close to 0.86, Mg/Ca and SO4/Cl weak showed that the seawater begins to invade the freshwater of the Plio-quaternary aquifer of Essaouira basin. This intrusion demonstrated by ionic ratios and corroborated by isotopic approach and the combined use of oxygen-18 contents and chlorides has a mixing rate of 15.9% at the well 11/51, 14.5% at the sample 45/51, 13.2% at the well 149/51, 13.3% at point O114 and 12.8% at the well O94. However, the results of the hydrogeochemical and isotopic approach suggest intrusion up to 2 km from the sea; this reflects a warning sign about the groundwater deterioration of the study area.

Characteristics and impacts on the groundwater of the Guriri beach resort, São Mateus, ES, Brazil

Water abstraction from phreatic aquifers allows easy access at low cost. However, these waters’ direct consumption can be harmful, especially in unsewered areas where domestic effluents are discharged into cesspits. This study assesses the quality of the groundwater explored by the Guriri beach resort residents. Samples from 35 residential wells were characterized, considering physicochemical and microbiological parameters. The water balance (rainfall–evapotranspiration), proximity to the shoreline, and separation between the well and the cesspit were taken into account in the interpretations. The evaluation with statistical tests (mean and correlation), graphs (Piper and Gibbs), and multivariate techniques (PCA and HCA) allowed the separation of two chemically distinct groups of waters. One from shallow wells (3 to 4 m depth) with lower electrical conductivity (EC) and acidic characteristics and the other gathering the deeper wells (11 to 13 m) with higher EC and neutral pH. All samples were classified as freshwater (TDS < 1 g/L), but its quality was compromised by permissible values infractions for pH, FeT, Cl−, HCO3− and by the presence of thermotolerant coliforms and E. Coli, in 50 and 20% of the wells, respectively. The participating residents were instructed on how to treat the waters by filtration and chlorination techniques. The effects of marine intrusion were absent. Moreover, the alternation between months with negative and positive water balance explains the groundwater EC values variation due to the accumulation and leaching of salts to the aquifer. The study revealed the aquifer vulnerability and the need for higher protection of this vital water source.

Hydrochemical and statistical study of the groundwater salinization in the region of Gabes in Tunisia

Marine intrusion is the most serious problem facing aquifers in coastal areas. These aquifers are considered as important sources of freshwater, especially in arid areas. The Gabes Jeffara aquifer, located in south-eastern Tunisia, has been recognized as an industrial area specialized in mining phosphate processing industry. Furthermore, the region has also been intensively exploited to supply the growing needs of agriculture and domestic sectors. Degradation of groundwater and the possibility of marine intrusion became a serious concern of the communities. This work proposes a multidisciplinary investigation involving hydro-geochemical and geostatistical techniques to investigate the characteristics of groundwater quality and identify the origin of its salinization. For this purpose, 43 water samples were conducted and analyzed in different locations of the study area (Ghannouch and Mareth cities). Electric conductivity, pH, salinity and major ions were measured and analyzed. Piper and pie diagrams, and geostatistical analysis were used to assess groundwater mineralization. Results show that dominant chemical facies are Na-Cl-Ca-SO4 (sodium, chloride, calcium, sulphate) due to rock-water interaction, suggesting that dissolution of halite was the main mineralization source of groundwater in the study area. However, saltwater intrusion was shown to control groundwater quality in some points so we can talk about a local saltwater intrusion.

Impact of climate change on the water balance of the Apuo-Versilia plain acquifer (Tuscany, Italy)

The authors drafted the water balance of the multi-layer aquifer of the Apuo-Versilia Plain, (Provinces of Lucca and Massa- Carrara) extending for about 152 km2. The water budget, relating to the average year of the period 2010-2012, includes both natural and anthropic terms. Availability of data allowed to calculate with a good approximation some terms (rain water infiltration, groundwater pumping, losses of aqueduct pipelines and sewers) while others (infiltration from water courses, draining of land reclamation systems) have been calculated with methods designed ad hoc but with poor validation. The budget closes with a positive balance of 56 million m3/year, which correspond to the outflow from the aquifer to the sea minus the marine intrusion: there is no data to calculate this term, which we have taken as the unknown term of the balance equation. Therefore, the budget is rough, but it allowed us to estimate the effects of climate change for two decades in the near future (2030-2040 and 2050-2060) according to two emission scenarios, RCP4.5 and RCP8.5: the recharge would be reduced 11% in 2036 and 15% in 2056. In these budgets, we have not considered the variations in anthropic terms because we have no elements to predict them. Climate change, which also will bring about an increasing of marine intrusion, will probably cause a greater use of groundwater. This could alter the balance of the hydrogeological system, which has so far shown a substantial stability, as demonstrated by the monitoring of piezometric levels in the Plain.

Assessment of groundwater mineralization of alluvial coastal aquifer of essaouira basin (Morocco) using the hydrochemical facies evolution diagram (HFE-Diagram)

The relation between the hydrochemical variation and the marine intrusion in the coastal alluvial aquifer of Essaouira basin (Morocco) was characterized by the major ionic ratios, the ratio Br−/Cl−, the hydrochemical facies evolution diagram (HFE-Diagram), and by the stable isotopes of oxygen and hydrogen (δ18O and δ2H). The results of major ionic ratios have shown that groundwater mineralization is controlled by the dissolution phenomenon and by the inverse Bases Exchange phenomenon caused by the marine intrusion. Br−/Cl− ratio shows that some water points are contaminated by seawater. The application of HFE-Diagram shows that the samples of the 1990 are grouped in the SW + i4 (52%) and i3 (14%) sub-stages. The samples of 1995 campaign show an evolution from the i1 (3%) sub-stage towards the FW + i4 (38%) sub-stage by reflecting the advancement of seawater in the aquifer. Samples representing the 2009 campaign are characterized by the dominance of the f1 (56%) sub-stage relative to the SW + i4 (38%) sub-stage, suggesting the trend of the aquifer towards the equilibrium phase due to the significant recharge that known this aquifer. While the samples of the 2015 campaign are dominated by the i3 (49%) and SW + i4 (32%) sub-stages reflecting the re-contamination of the aquifer by seawater. However, the groundwater mineralization of the alluvial coastal aquifer of Essaouira basin is controlled by the dissolution phenomenon and by the bases exchange phenomenon caused by the marine intrusion. Exploiting the results of this paper can lead to better management of the aquifer by identifying the areas contaminated by seawater.

Mapping of the vulnerability to marine intrusion “in coastal Cherchell aquifer, Central Algeria” using the GALDIT method

Located in the south of the western Mediterranean, in the central Algerian region, the Cherchell coastal aquifer has participated over time in the economic development of the region (agriculture and seaside tourism). The construction of the Boukerdene dam in the watershed of the region, thus the exploitation of the aquifer in response to the excessive demand of agriculture and the potable water supply, has caused the piezometric level of the aquifer to decline and threatens its sustainability and makes it more vulnerable to marine intrusion, noting that no work has been realized in this study area despite the inestimable value of this aquifer in the region, it's the only aquifer in Cherchell town. The aim of this paper is to map the vulnerability of this aquifer to marine intrusion, based on the proven methodology of the GALDIT model for coastal aquifers combined with Geographic Information Systems (GIS). The GALDIT methodology requires six input parameters: groundwater occurrence (G), aquifer hydraulic conductivity (A), groundwater head above sea level (L), distance from the shore (D), impact of the existing status of seawater intrusion l'impact (I), and thickness of the aquifer (T).The results indicate low to moderate vulnerability upstream and high vulnerability downstream. This high vulnerability can be as much as 700 m from shoreline inland. This vulnerability is mainly due to the hydrological disruption linked to the construction of the Boukerdene dam, which reduces surface water inflows. These results provide a basic tool for local managers and decision-makers, for future management and protection strategies for the Cherchell area aquifer in the face of marine intrusion.

Global warming and groundwater from semi-arid areas: Essaouira region (Morocco) as an example

Climate change is undoubtedly becoming a subject of great concern for public authorities in all regions of the globe, in particular, the regions under Saharan, arid, and semi-arid climate. In this regard, this study aims to assess the effect of climate change on groundwater from semi-arid environments, taking the Essaouira basin as an example. The climate approach shows a downward trend in precipitation from 12 to 16% and an increase in temperature from 1.2 to 2.3 °C, and this during the last three decades. A continuous decline in the piezometric level exceeding 12 m for the Cenomanian–Turonian aquifer and 17 m for the Plio-Quaternary aquifer has been observed. The groundwater mineralization is controlled by the dissolution of evaporate and carbonate minerals, by the bases exchange phenomenon, and by the marine intrusion, especially in Plio-Quaternary aquifer. Also, the groundwater quality in the study area deteriorates gradually over time and space. However, the results of this study confirm that the groundwater from Essaouira basin is vulnerable to the global warming.

Salt variation induces oxidative stress response in aquatic macrophytes: The case of the Eurasian water-milfoil Myriophyllum spicatum L. (Saxifragales: Haloragaceae)

Wetlands are very fragile systems and susceptible to being affected by human activity. S'Albufera de Mallorca Natural Park is the main wetland in Mallorca Island (Spain), and undergoes a salinization process derived from the overexploitation of adjacent aquifers, which favors marine intrusion. The objective was to evaluate the effects of salinity changes in a channel in s'Albufera de Mallorca through the analysis of biomarkers of oxidative stress in the submerged macrophyte Myriophyllum spicatum. Six different points were analysed along a channel characterized by different salinity values, ranging from ~2 to ~11. The % of macrophyte coverage in the studied stations followed an inverse salinity pattern with greater coverage in areas of low salinity and minimal coverage in those with higher saline concentration. The photosynthetic pigments index (D430/D665), determined in M. spicatum leaves, was significantly higher at the stations most affected by salinity. All antioxidant enzyme activities – catalase, superoxide dismutase, glutathione peroxidase and glutathione reductase – followed a similar pattern of response with an increase in activity as salinity increases. Similarly, the levels of malondialdehyde, as marker of lipid peroxidation, were also increased the stations with the highest salinity. In conclusion, marine water intrusion causes an increase in the salinity of inland waters in s’Albufera de Mallorca, which is evidenced by the increase in the antioxidant enzyme activities and oxidative damage.

Groundwater quality in semi-arid environments (Essaouira Basin, Morocco)

Hydrochemical, isotopy, and geostatistical approaches have been used to highlight the processes that control groundwater salinization in the detrital aquifer of Essaouira (Morocco). The hydrogeochemical approach shows that: (i) The dissolution of halite, gypsum, and/or anhydrite would contribute to the salinization of groundwater, (ii) the basic-exchange and marine intrusion phenomena are generally responsible for the wide variation in cation concentrations in groundwater. The use of this water for drinking purpose requires treatment before its use. For irrigation purpose, groundwater of the studied aquifer remains suitable for plants supporting high salinity. The nitrate contamination study shows that highest concentrations could be explained by: (i) the high concentration of tourism activity (Sidi Kaouki zone), (ii) the absence of sanitation network and wastewater treatment plant, and (iii) waste from livestock during watering. The stable isotope contents show that (i) Plio-Quaternary aquifer recharge is provided by the direct infiltration of Atlantic precipitation and (ii) the groundwater of the study area has undergone evaporation phenomena and marine intrusion. While the Geostatistics technique confirmed the results obtained by the hydrogeochemical and isotopic approach, highlighting the processes controlling the groundwater mineralization of the study area. However, the results of this paper can be used for better and realistic management of the water resource.

Characterizing NWP Model Errors Using Doppler-Lidar Measurements of Recurrent Regional Diurnal Flows: Marine-Air Intrusions into the Columbia River Basin

Abstract Ground-based Doppler-lidar instrumentation provides atmospheric wind data at dramatically improved accuracies and spatial/temporal resolutions. These capabilities have provided new insights into atmospheric flow phenomena, but they also should have a strong role in NWP model improvement. Insight into the nature of model errors can be gained by studying recurrent atmospheric flows, here a regional summertime diurnal sea breeze and subsequent marine-air intrusion into the arid interior of Oregon–Washington, where these winds are an important wind-energy resource. These marine intrusions were sampled by three scanning Doppler lidars in the Columbia River basin as part of the Second Wind Forecast Improvement Project (WFIP2), using data from summer 2016. Lidar time–height cross sections of wind speed identified 8 days when the diurnal flow cycle (peak wind speeds at midnight, afternoon minima) was obvious and strong. The 8-day composite time–height cross sections of lidar wind speeds are used to validate those generated by the operational NCEP–HRRR model. HRRR simulated the diurnal wind cycle, but produced errors in the timing of onset and significant errors due to a premature nighttime demise of the intrusion flow, producing low-bias errors of 6 m s−1. Day-to-day and in the composite, whenever a marine intrusion occurred, HRRR made these same errors. The errors occurred under a range of gradient wind conditions indicating that they resulted from the misrepresentation of physical processes within a limited region around the measurement locations. Because of their generation within a limited geographical area, field measurement programs can be designed to find and address the sources of these NWP errors.

Electrodialysis reversal as an alternative treatment for producing drinking water from brackish river water: A case study in the dry season, northeastern Brazil

Water scarcity has been a cause of concern throughout the world. Brazil, home of the largest freshwater reserve in the world, is no different, as it suffers recurring problems of scarcity and the uneven distribution of water reserves. This research evaluated the Electrodialysis Reversal (EDR) process applied to the treatment of brackish water from the Almada River Basin, southern Bahia, known as the Cocoa Region, in northeast Brazil. In periods of water scarcity, marine intrusion causes high levels of salinity in rivers and freshwater wells. Water collected directly from the Almada River, with high concentrations of sodium and chloride, 661.3 mg/L 1,091.9 mg/L respectively, and electrical conductivity about 2.98 mS/cm, was treated in pilot-scale EDR equipment. The treatment reduced conductivity by 70–80 %, especially removal of sodium and chloride, found in higher concentrations than those found in higher concentrations than those established in regulations for drinking water. After EDR treatment under two different values of applied electric current, the water reached levels suitable for consumption. The system operated at 80 % water recovery rate. The power consumption calculated for each treatment was 1.06 kWh or 2.6 kW/m3 and 0.66 kWh or 1.7 kW/m3. EDR proved to be an efficient alternative to guarantee the supply of drinking water during periods of severe drought.

Interrelation prokaryotic community-aquifer in a carbonate coastal environment

Seawater intrusion in coastal aquifers produces strong physico-chemical gradients. The bacterial community can play a significant role in the biogeochemical reactions in these specific environments. The objective of this study was to analyze the prokaryotic community and determine its influence along a vertical saline gradient (from freshwater to saltwater) and pH (from 9 to 5) in 16 m of groundwater column in a carbonate coastal aquifer. Representative samples taken from the freshwater, interface and saltwater were amplified using primers of the hypervariable V3–V4 region of the 16S rRNA gene and sequenced using NGS technology (Next Generation Sequencing) in order to reveal the prokaryotic microbiome, both Bacteria and Archaea. There were clear differences in the prokaryotic community along this profile, in both qualitative and relative quantitative terms. The freshwater layer, in the upper part of the aquifer, was richer in the number of species and was dominated by Proteobacteria which were replaced by Firmicutes and Euryarchaeota as depth and salinity increased. All groundwater levels had, in general, a relatively high diversity of OTUs, most of them showing low relative abundances (< 0.1%). There was a clear interdependence between physicochemical and microbial parameters; firstly, the marine intrusion created a vertical salinity gradient where only the species adapted to these environments could develop. Secondly, the microbial action modified the environment, generating in the upper part an anomalous alkaline pH where specialist species live, such as Desulfonatronum cooperativum. As for the interface and saltwater layers, they were clearly acid due to the activity of several sulfates reducing bacteria species, such as Sulfuriflexus mobilis or Desulfomicrobium baculatum. The latter species is able to oxidize several metals, resulting in a pH decrease in the groundwater and an increase in the concentration of these metals. The acidification mediated by bacteria plays a significant role since it can dissolve the carbonate rock, favoring the landward advance of marine intrusion.