SOL40: forty years of simulations under a climate and land use change scenario

<p>Nowadays, one major issue concerns the land-use change due to urban developments that alters the basin response to meteorological events. With less storage capacity and more rapid runoff, urban river basins rise more quickly during storms and have higher peak discharge rates than rural catchments.</p><p>An exemplary case of this situation is the city of Milan and its whole territory that extends towards north that collects meteoric precipitation, through the Seveso, Olona and Lambro (SOL) rivers plus a number of minor tributaries for a total drainage surface of about 1300 km<sup>2</sup>.</p><p>In order to assess the impact of anthropogenic development on urban catchment scale hydrology, a reanalysis of 40 years of simulations has been carried out with the Curve Number (CN) map based on current land use, and compared to simulations with the CN maps derived using past land use.</p><p>A coupled hydro-meteorological system which comprises the physically based rainfall-runoff hydrological model FEST-WB, developed by the Politecnico di Milano and the ERA5-Land hourly dataset from 1981 to present, provided by ECMWF under the framework of Copernicus Climate Change Service Programme has been built.</p><p>The study (named as SOL40) exactly analyses 40-years trends of the main meteorological (air temperature, precipitation, etc.) and hydrological variables (soil moisture, evapotranspiration and runoff) over the SOL area, and try to quantify and separate the impact of land use change from the climate change scenario.</p>

Unraveling Sources and Climate Conditions Prevailing during the Deposition of Neoproterozoic Evaporites Using Coupled Chemistry and Boron Isotope Compositions (δ11B): The Example of the Salt Range, Punjab, Pakistan

In this study, the ion concentrations (K+, Na+, Ca2+, Mg2+, Cl−, SO42−, Br−, NO3−, and B3+) and boron isotope compositions (δ11B) of 34 halite and brines samples from the Neoproterozoic Salt Range Formation, Punjab, Pakistan were studied. Relation among B3+ vs. Mg2+, B3+ vs. SO42−, δ11B vs. B3+, and δ11B vs K+ were observed, they indicated that these elements originate from multiple sources and the end members were identified as seawater, B desorption from clays, and meteoric precipitation. Halite samples of the area under study displayed a Na-HCO3-type to Ca-Cl type sedimentary basin of deposition, on δ11B vs. 1/B plot. Molar ratios of B/Cl vs. δ11B revealed the addition of B in some of the studied samples from desorption of clay minerals. This type of diagenetic desorption of B from clays is the consequence of a stress driven mechanism, generated in the proximity of a decollement zone. Results confirm that the number of B stable isotopes that fractionate between the brine and the halite is low. The halite δ11B from the Salt Range Formation vary from +2.1 to +24.4‰, compared to +17.3 to +26.1‰ in the salt pool brines, and suggest that boron isotope compositions are controlled by the δ11B of the B sources. The positive relationship between the boron content and the corresponding δ11B indicates a higher salinity and drier paleoclimate conditions during the formation process, associated with a high evaporation rate in the Late Neoproterozoic time. Presence of elevated δ11B in the present study, demonstrate compatibility with other marine basins of the world, arising the need for further investigations to better characterize the 11B-enriching processes.

Different runoff patterns determined by stable isotopes and multi-time runoff responses to precipitation in a seasonal frost area: a case study in the Songhua River basin, northeast China

Runoff patterns are crucial to determine the hydrological response to climate change, especially in a seasonal frost area. In this study, multi-time runoff responses to meteoric precipitation for the period from July 2014 to June 2016 and the period from 1955 to 2010 were obtained to identify different runoff patterns in the Songhua River basin, northeast China, based on six stations. Two distinctly different runoff responses are exhibited: a periodic one in response to precipitation in the Nen River and a constant one in the Second Songhua River under different scales. Stable isotopes in the plain with diverse characteristics also supported these runoff patterns. What is more, gradual runoff relatively less sensitive to precipitation in the Second Songhua Rive was attributed to upstream dam constructions. Furthermore, the Second Songhua River contributes more water to the main stream during January to March at the seasonal scale and in the 2000s at the annual scale, with low precipitation during those periods. This study could have implications for water management in the Songhua River basin.

Hydrogeochemical Characterization of a Warm Spring System in a Carbonate Mountain Range of the Eastern Julian Alps, Slovenia

The Alps represent an area where many deep groundwater circulations occur as thermal springs. In the Bled case study, the thermal water temperature, at it is discharged to the surface, is between 19–23 °C. In order to determine the extent (e.g., geometry) and the origin of the pronounced deep circulation system in the Bled area, chemical and isotopic measurements of waters from different hydrogeological systems were performed (e.g., surface water, thermal water, fresh groundwater). Hydrogeochemical methods were used to tie together the above-mentioned parameters. The results have shown that thermal outflow in Bled is determined by the presence of a deep-water circulation system, where the dissolution of carbonates minerals is the main hydrogeochemical process affecting chemical components of natural water flow. The correlation of the major ions suggests that the recharge area is represented by both limestone and dolomite rocks. Moreover, the results of δ18O and δ2H of all samples indicate that the recharge is mainly meteoric precipitation. The recharge altitude was estimated for two sampled fresh groundwater springs. The isotopic compositions of those two springs suggest the range from δ18O = −8.68‰, δ2H = −57.4‰ at an elevation of 629 m to δ18O = −9.30‰, δ2H = −60.1‰ at an elevation of 1216 m. The isotopic analysis has confirmed that the thermal water recharges from altitudes of 1282–1620 m a.s.l.

Presence and Distribution of Fluoride Ions in Groundwater for Human in a Semiconfined Volcanic Aquifer

Dental and emaciated fluorosis is derived from the chronic intake of fluoride ions (F−) by consumption of food, tooth products and drinking water from groundwater. Recent reports indicate that in some regions of Mexico, the incidence of fluorosis in temporary and permanent dentitions have increased in recent years. The purpose of the present investigation was to determine the presence and distribution of F− ions in semi-confined aquifers, located in the basins of Lerma-Chapala and Valley of México. Temperature (T), pH, electrical conductivity (EC) and alkalinity were determined in situ, in 27 groundwater wells. The hardness, chloride ions (Cl−), free chlorine (Cl2), total dissolved solids (TDS) and bicarbonates (HCO3−), were determined in the laboratory. The high content of bicarbonate ions (HCO3−) is associated with the alteration of silicates and the presence of chloride ions (Cl−) due to the anthropogenic activity. The highest value of fluoride ions (F−) (1.31 mg/L) was identified in a well of the Lerma-Chapala basin and in 25% of the samples (1.056 mg/L) of the Valley of México basin. The groundwater in the Lerma-Chapala basin is of the Ca-HCO3 type and the water in the Valley of Mexico basin is Na-HCO3 and Ca-HCO3. According to the Gibbs diagram, the water of the Toluca Valley aquifer is recharged by local meteoric precipitation and consequent the water-rock interaction occurs. The correlation analysis shows the significant relationship between F− and CE (R = 0.5933), F− and alkalinity (R = 0.6924), F− and HCO3− (R = 0.6924) and F− and TDS (R = 0.5933). The correlations confirm that the content of fluoride ions present in groundwater is associated with high concentrations of bicarbonate ions and the presence of sodium, due to a process of alteration of the silicates.

Overview of the oxygen isotope systematics of land snails from North America

Continental paleoclimate proxies with near-global coverage are rare. Land snail δ18O is one of the few proxies abundant in Quaternary sediments ranging from the tropics to the high Arctic tundra. However, its application in paleoclimatology remains difficult, attributable in part to limitations in published calibration studies. Here we present shell δ18O of modern small (<10 mm) snails across North America, from Florida (30°N) to Manitoba (58°N), to examine the main climatic controls on shell δ18O at a coarse scale. This transect is augmented by published δ18O values, which expand our coverage from Jamaica (18°N) to Alaska (64°N). Results indicate that shell δ18O primarily tracks the average annual precipitation δ18O. Shell δ18O increases 0.5–0.7‰ for every 1‰ increase in precipitation δ18O, and 0.3–0.7‰ for every 1°C increase in temperature. These relationships hold true when all taxa are included regardless of body size (ranging from ~1.6 to ~58 mm), ecology (herbivores, omnivores, and carnivores), or behavior (variable seasonal active periods and mobility habits). Future isotopic investigations should include calibration studies in tropical and high-latitude settings, arid environments, and along altitudinal gradients to test if the near linear relationship between shell and meteoric precipitation δ18O observed on a continental scale remains significant.