Four-decade (1977-2017) landscape tale of tourist reservoir hotspot El Piñol-Guatapé, Colombia.

Efficient management of land use/land cover (LULC) features is vital for a balanced sustainable ecosystem. Thus, this work aimed to document the LULC changes in the less studied El Peñol-Guatapé reservoir, Antioquia, Colombia, especially in the reservoir area due to the construction of a hydro-electric power plant. For this study, Landsat images of 1977, 1986, 1997, and 2017 were used and the results indicated an increase in the settlement area and road networks by 0.10 and 0.60%, respectively, while during 1986 to 2017, cropland, plantation, dense forest, and open forest areas presented an increase of 0.52, 1.06, 2.87 and 2.61%, respectively. However, the marshy vegetation, scrub forest and fallow land decreased to - 0.51, - 3.79 and - 4.29%, respectively, in the same period. The water body before and after the completion of reservoir project denoted an increase from 13.1 km2 in 1977 to 45.7 km2 in 1986. This study provides a first-hand report on LULC dynamics in this tourism dominated municipalities that will serve as a reference for ecosystem management to reconcile the conflicts between different LULC classes in ecologically enriched regions.

Groundwater chemistry and demarcation of seawater intrusion zones in the Thamirabarani delta of south India based on geochemical signatures.

Sub-surface water samples from the delta of Thamirabarani River of south India were evaluated for human health risks and seawater intrusion using the geochemical signatures. Electrical conductivity (EC), total dissolved solids (TDS), pH and the concentrations of major cations and anions in 40 samples collected during the winter (January) and summer (July) of 2018 show comparable values. Subsequently, the results were verified with respect to the international drinking water quality standards. The piper trilinear diagram shows mixed Ca-Mg-Cl, Na-Cl, Ca-HCO3 and mixed Ca-Na-HCO3 facies in the samples. Similarly, the plenteous of cations are sequenced as Na+ > Ca2+ > Mg2+ > K+ and the plenteous of anions are sequenced as Cl- > SO42- > HCO3->Br- > NO3- > PO4-. Gibbs plots illustrate that rock-water interaction and evaporation control the geochemistry of sub-surface water. More than 40% of the samples are unsuitable for drinking, and their higher EC and TDS values reflected the seawater intrusion, in addition to the anthropogenic activities (salt panning). Interrelationship between ions of sub-surface water was used to get a better insight into the saline water intrusion in the study area. To mitigate the river water salinization and seawater incursion in the aquifers, engineering solution such as weir construction across the Thamirabarani River near Mukkani village has been proposed. After construction of the weir, freshwater in the river can be diverted to the salt-affected and seawater-intruded areas to improve the scenario.

Coastline variability of several Latin American cities alongside Pacific Ocean due to the unusual "Sea Swell" events of 2015.

This study aims to report the short-term coastline dynamics and inundation limits of coastal cities along the Eastern Pacific due to the sea swell events that occurred during April to May 2015. The multi-temporal satellite datasets from Landsat such as Enhanced Thematic Mapper (L7 ETM+) and Operational Land Imager/Thermal Infrared Sensor (L8 OLI/TIRS) of different periods before and after the swell events were used to identify the shoreline changes. The satellite images were pre-processed using ERDAS imagine 9.2, and the coastline was digitized in ArcGIS 10.4.1 for ten cities spread across from Mexico to Chile (in Pacific coast) using the spectral water indices, and the shoreline change rate and erosion/accretion pattern at each transect were estimated using the statistical parameters embedded in Digital Shoreline Analysis System (DSAS). The maximum erosion and accretion were observed in El Salvador (268 m) and Huatulco (Mexico) (115 m), respectively. Likewise, the maximum inundation was observed in El Salvador with 268 m and Acapulco (Mexico) with 254 m, and the tide gauge data suggest a possible relation to the bathymetry and the geomorphological conditions of the coast. Overall, the results indicate that the Eastern Pacific Ocean side sea swell events has led to extreme coastal flooding in recent years due to the increase in the mean sea level and the unpredictable variation in El Niño/Southern Oscillation events. Graphical abstract.

Metal enrichment in beach sediments from Chennai Metropolis, SE coast of India.

A survey on the Partially Extracted Trace Metals (PETMs) concentration (Fe, Mn, Cr, Cu, Ni, Co, Pb, Zn, Cd) in beach sediments is reported for the first time from 57 different locations in Chennai Metropolitan City of Southeast coast of India. The concentration of PETMs suggests that they are mainly concentrated with organic matter in the crowded part of the industrial regions in the beaches from the northern part rather than the tourist beaches in the southern part of the city. The comparison on enrichment of trace metals indicates higher values of Pb, Ni in the beaches than lowest effect level (LEL) and effects range low (ERL) than the tourist beaches.

Metal concentrations in water and sediments from tourist beaches of Acapulco, Mexico.

A survey on the metal concentrations (As, Ba, Cd, Co, Cr, Cu, Fe, Mn, Ni, Pb, Sr, V, Zn) in beach water and sediments is reported from the tourist destination of Acapulco city on the Pacific coast of Mexico. The concentration of dissolved trace metals (DTMs) in beach water and acid leachable trace metals (ALTMs) in sediments indicated that they are anthropogenic in nature due to the increased tourist activities in the crowded beach locations. The statistical analysis indicates Fe and Mn play a major role as metal scavengers in both the medium (water and sediment) and the higher value of other metals is site specific in the study area, indicating that they are transported from the local area. Comparison results suggest that the beach water quality has deteriorated more than the sediments and special care needs to be taken to restore the beach quality.