Abundant Precipitation in Qilian Mountains Generated from the Recycled Moisture over the Adjacent Arid Hexi Corridor, Northwest China

The observed precipitation was suggestive of abundant precipitation in upstream Qilian mountains and low precipitation in the downstream oasis and desert in an endorheic basin. However, precipitation in mountains generated from the recycled moisture over oasis and desert areas has rarely been studied. The climatological patterns of water vapor from 1980 to 2017 in the Qilian Mountain Region (QMR) and Hexi Corridor Region (HCR) were investigated by the European Centre for Medium-Range Weather Forecasts Interim reanalysis dataset and the Modern-Era Retrospective Analysis for Research and Application, Version 2 reanalysis dataset. The results suggest that the precipitable water content decreases from the adjacent to the mountain areas. There are two channels that transport water vapor from the HCR to the QMR in the low troposphere (surface—600 hPa), suggesting that parts of recycled moisture generated from evapotranspiration over the oasis and desert of the HCR is transported to the QMR, contributing to the abundant precipitation in the QMR. This indicates that the transport mechanism is probably because of the “cold and wet island effect” of the cryosphere in QMR. This is likely one of the essential mechanisms of the water cycle in endorheic river basins, which has rarely been reported.

Lake area and volume variation in the endorheic basin of the Tibetan Plateau from 1989 to 2019

The Tibetan Plateau, known as "the third pole of the Earth", is a region susceptible to climate change. With little human disturbance, lake storage changes serve as a unique indicator of climate change, but comprehensive lake storage data are rare in the region, especially for the lakes with an area less than 10 km2 which are the most sensitive to environmental changes. In this paper, we completed a census of annual lake volume change for 976 lakes larger than 1 km2 in the endorheic basin of the Tibetan Plateau (EBTP) during 1989–2019 using Landsat imagery and digital terrain models. Validation and comparison with several existing studies indicate that our data are more reliable. Lake volume in the EBTP exhibited a net increase of 193.45 km3 during the time period with an increasing rate of 6.45 km3 year−1. In general, the larger the lake area, the greater the lake volume change, though there are some exceptions. Lakes with an area less than 10 km2 have more severe volume change whether decreasing or increasing. This research complements existing lake studies by providing a comprehensive and long-term lake volume change data for the region. The dataset is available on Zenodo (https://doi.org/10.5281/zenodo.5543615, Wang et al., 2021).

Spatiotemporal Response of Hydrological Drought to Meteorological Drought on Multi-Time Scales Concerning Endorheic Basin

Under the controversial background of “Northwestern China is gradually developing towards warm and humid”, how hydrological drought responds to meteorological drought at the endorheic basin is of great significance. To address this problem, we first analyzed the spatiotemporal variation of meteorological and hydrological droughts at Tarim Basin River from 1960 to 2014 by using the daily standardized precipitation index (SPI) and daily standardized terrestrial water storage index (SWSI) based on the reanalysis data. Thereafter, we explored the spatiotemporal response of hydrological drought to meteorological drought on the multi-time scale by using the cross-wavelet transform method, Ensemble Empirical Mode Decomposition (EEMD), and correlation analysis. We find that: (1) both meteorological and hydrological droughts signified a gradually weakened trend in time; (2) meteorological and hydrological drought have significant resonance periods on the 10-month time scale and the 8-year time scale; (3) hydrological drought generally lags behind the meteorological drought by 7 days in plains areas, while it can last as long as several months or even a year in mountainous areas.

Geophysical evi-dence of the 1912 earthquake rupture along the central fault system of the Acambay Graben, Central Mexico

In this work, we have applied two geophysical techniques in two different areas of potential interest for paleoseismological assessment of the active faults of the Acambay graben. The main goal was to localize segments of buried faults suspected to break the surface during the 1912 Acambay Earthquake, in order to (1) identify favorable sites for paleoseismological investigation purpose and (2) extrapolate the data obtained with a paleoseismic trenching. On the one hand, Electromagnetic Induction (EMI) Method was used to map the horizontal variation of the apparent resistivity in order to detect the 1912 surface rupture of the Temascalcingo fault in the alluvial plain of the Lerma River. On the other hand, within a volcanic edifice, the Electrical Resistivity Tomography (ERT) tech-nique was used to characterize the electrical resistivity distribution along a profile in or-der to detect and localize the San Pedro fault, partially buried in a Holocene sedimentary filling of a small endorheic basin. Results of these studies allow defining location and orientation of the structures that potentially broke the surface during the 1912 earthquake and are partially hidden by recent deposits filling the tectonic depressions. Good correla-tion between ERT subsurface to deep imagery of faults and a trench survey which cuts across the San Pedro fault trace, illustrate the pertinence to use such techniques for pale-oseismological investigation purpose in volcano-sedimentary environments.

Shallow groundwater chemical evolution, isotopic hyperfiltration, and salt pan formation in a hypersaline endorheic basin: Pilot Valley, Great Basin, USA

Endorheic basin brines are of economic significance as sources of boron, iodine, magnesium, potassium, sodium sulfate, sodium carbonate, and tungsten, and they are a major source of the critical metal lithium. Although evaporation is the primary hypersalinization driver for evaporative water bodies, recent investigations have proposed more novel mechanisms for some subsurface brine. This investigation explores shallow groundwater hypersalinization. The chemical evolution and isotopic fractionation of shallow hypersaline groundwater in the clay-rich arid endorheic basin sediments of Pilot Valley, Great Basin (USA), were investigated. Groundwater evolves from fresh in the mountain bedrock and alluvial fans, to brackish and saline at the alluvial fan–playa interface, and to hypersaline in the upper 12 m of basin sediments. Alluvial fan systems are isolated from each other and have varying groundwater 3H and 14C travel times. Nonevaporative in-situ isotopic fractionation of up to −8‰ in δ18O is attributed to clay sequence hyperfiltration. Groundwater flow-path sulfate and chloride mineral dissolution is the primary driving mechanism for both interface and basin groundwater evolution. Evaporation only impacts the groundwater quality in a small portion of the basin where the groundwater is within ~1 m of the ground surface. Here capillary action carries dissolved soluble salts to the land surface. Episodic flooding redissolves and carries the precipitated salt to the annually flooded salt pan where it accumulates as a salt crust during the dry season. The Pilot Valley model may help explain the buildup accumulative layers of soluble salt that when remobilized becomes subsurface brine.

Length-weight relationship, condition factor, and distribution of spotted barb (Barbodes binotatus Valenciennes, 1842) in Lake Tamblingan Bali

Tamblingan Lake is a volcanic lake located in the caldera of Mount Lesung a rain-fed lake in a confined endorheic basin and there is no inflow or outflow. Nyalian is a type of fish from the Cyprinidae family that is quite common compared to other fish in its class in Tamblingan Lake. Information on the growth and distribution of these fish parameters in Tamblingan Lake does not exist. This study aims to analyze and explain the growth patterns of Barbodes binotatus, especially the length-weight relationship, condition factor, and their distribution in the waters of Tamblingan Lake. The research was conducted in Tamblingan Lake from January to June 2019 using a modify gill nets with the mesh size 0.5; 1.0; 1.5; 2.0; 2.5; 3.0 in centimeter. The sampling done in five locations. The length-weight relationship analysis used the power regression. The fish sample found was 204 individuals during the study with a range of total length was 5.2 – 15.0 cm. The equation of length-weight relationship is W = 0.0051 L3.387. The value of b formed based on this equation is 3.387 with a positive allometric growth pattern.The condition factor values ranged from 0.587 to 1.246. Barbodes binotatus spread in the litoral area where there are many aquatic plants. This information of nyalian fish could use as the basis for fish resource management in Tamblingan Lake.

The discovery of a microbialite-associated freshwater fish in the world’s largest saline soda lake, Lake Van (Turkey)

Lake Van is the largest saline soda lake in the world and one of the world’s few endorheic lakes of greater than 3,000 km2 surface area. Despite its huge size, no fish species have so far been known to permanently occur in this lake due to its extreme environmental conditions. Here, we report the discovery of a fish population that permanently inhabits some of the unique microbialites of the lake, at a maximum depth of 13 m and about 500 m offshore. We tested whether this is an undescribed species or a new occurrence of a known species. A molecular and morphological examination showed that the newly discovered fish represents an isolated population of Oxynoemacheilus ercisianus, the only nemacheilid loach native to the freshwater tributaries of the Lake Van endorheic basin. Our further hypotheses on the prediction that (a) stream fishes would have a more anterior placement of fins than lake fishes were supported; but, that (b) stream fishes would be more slender bodied than their lake conspecifics was not supported. The lake dwelling population also shows very small sequence divergence (0.5% K2P distance) to its stream dwelling conspecific in the mtDNA-COI barcode region. The notable morphological difference with minute molecular divergence implies that the newly discovered population might have lost its link to freshwater during desiccation and transgressional phases of the Lake Van, and has adapted to a life on the microbialites.