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Alpine regions’ groundwater is crucial to the worldwide hydrological cycle. However, due to the harsh environmental conditions, the distribution and evolution characteristics await clarification. The study area was selected to be the Nagqu River Basin in the Nu-Salween River’s source region. In 2019-2021, we gathered 88,000 monitoring data from nine observation wells and examined the spatiotemporal groundwater table changes in various permafrost zones and freeze-thaw cycles. During the freezing period, entirely frozen period, thawing period, and entirely thawed period, the groundwater table change rates in the permafrost zone were 2.14, 1.54, 1.55, and 2.01 times larger than in the seasonal frost zone, and fluctuation amplitudes were 1.97, 1.28, 1.01 and 1.31 times larger. The average groundwater table change rate and fluctuation amplitude were greatest during the entirely thawed period and lowest during the thawing period, with the maximum change rate reaching 3.64 cm/d during the entirely thawed period of 2019-2020 in the permafrost zone and the minimum change rate of 0.12 cm/d during the thawing period of 2019-2020 in the seasonal frost zone. [ABSTRACT FROM AUTHOR]

To enhance our understanding of the regional hydroclimate in the Central Tibetan Plateau, different types of water samples were collected across the Naqu River basin in the summer (July, August) and winter (January, December) of 2017 for isotopic analysis. With Cuona Lake as the demarcation point, the δ18O values of the river water increased initially and then decreased from upstream to downstream along the river's mainstream. In the Naqu River system, a general decrease of δ18O values in the trunk stream of the lower reaches (from the head of Cuona Lake) was revealed owing to the gradual dilution of increased isotopically-depleted tributary inflow. Lakes play an important role in regulating runoff and changes in the levels of stable isotopes in rivers or streams. Additionally, the decrease of δ18O is controlled by processes involved in the 'isotopic altitude effect'. Larger contributions of winter precipitation in surface runoff at higher elevations would produce higher deuterium excess in stream water. On the regional scale, with Cuona Lake as the demarcation point, one of the clearest findings was that the river/stream's deuterium excess values decreased first and then increased from the south to the north in the summer; but there was a positive linear increase in the winter. From geographical and climatological perspectives, the changes of deuterium excess could result from increasing effects of summertime, and the generation of continental/local recycled and monsoonal water vapor in the surface runoff northward. The study area is at the critical transition between the Indian monsoon system in the South and the Northern belt of the westerlies, as revealed by the intermediate deuterium excess values. [ABSTRACT FROM AUTHOR]

Under the climate changes and human activities, large areas of lakes shrunk and wetlands degenerated. Evapotranspiration (ET) is the primary water loss in the water balance of closed-basin and lakes. However, ET is difficult to estimate, especially in the data-scarce or ungauged zones. For a closed lake without outflow, the inflow could be used to estimate the water shortage of ecological water demand. Based on meteorology data and the pan evaporation (ETpan) data, Penman-Monteith and Hargreaves Model were used to estimate potential evapotranspiration (ET0), which was used to estimate ET, and used the water balance model to assess the water inflow of Wolong Lake. PM model proposed the satisfactory estimation of ET0 from Wolong Lake. The empirical formula of the net radiation was built based on the coefficient that derived from data fitting with function of the measured ETpan and the estimated ET0. The temperature was the dominant factor for the increment of the ETpan. In the data-scarce or ungauged zones, ET0 could be used to evaluate the evapotranspiration from the lake surface (ETlake), instead of the ETpan. The results found that the inflow of Wolong Lake could not meet the demand of the evaporation and water volume advancement. [ABSTRACT FROM AUTHOR]

The aim of this study was to investigate the different performance of bioelectricity generation and wastewater treatment between constructed wetland (CW) respectively coupled with air-cathode microbial fuel cell (ACMFC) and microbial fuel cell (MFC) under a fed-batch mode. During a 75-day-operation, the voltage of CW-ACMFC and CW-MFC ranged from 0.36 to 0.52 V and from −0.04 to 0.07 V, indicating that the bioenergy output of CW-ACMFC was significantly higher than that of CW-MFC system. In addition, the maximum of power density of CW-ACMFC and CW-MFC was 4.21 and 0.005 mW m−2. Notably, the chemical oxygen demand (COD) and NH3-N removal efficiency of CW-ACMFC was slightly higher than that in CW-MFC, which resulted from a higher voltage accelerating the transport of electron donors and the growth of microorganisms and plants. This study possesses a probability of using ACMFC coupled with CW to enhance the pollutant removal performance in CW system. [ABSTRACT FROM AUTHOR]

The Huaihe River Basin is located in-between the north-south climate transitional zone in China and is China's important congested area and production base. The land-use of the environment was occupied by the land-use for social and economics. This paper aims to have a comprehensive understanding about land-use and vegetation evolution of the basin over the past 30 years. In view of 5 years (1985, 1990, 2000, 2005, and 2014) land-use data and remote sensing data about NDVI, land-use dynamic degree, and land-use transfer matrix were used to analyze the dynamics of land use. Spatial overlay was used to study vegetation change characteristics of the basin. The present study investigates the evolution trend of vegetation coverage based on spatial overlay analysis. We found that water bodies and urban lands of the basin increased during 1985-2014. On the other hand, the area of artificial vegetation, natural vegetation, and wetland were reduced. The impact was gradually increased by human intervention on various land use types. Overall vegetation coverage level shows deteriorative development, and distribution areas were discrete. The excellent vegetation coverage of natural vegetation and wetland didn't have obvious changes, but the high coverage significantly decreased. Taken as a whole, the natural vegetation coverage was reduced. The vegetation coverage level of artificial water in the land-use for social and economics had greatly increased, but the overall trend of vegetation coverage level of artificial vegetation and resident construction land showed a decreasing trend. [ABSTRACT FROM AUTHOR]

The Tibetan Plateau (TP) is the roof of the world and water towers of Asia. However, research on hydrological processes is restricted by the sparse gauge network in the TP. The distributed hydrological model is an efficient tool to explore hydrological processes. Meanwhile, the spatial distribution of precipitation directly affects the precision of distributed hydrological modelling. The latest TRMM 3B42 (V7) precipitation was evaluated compared with gauge precipitation at station and basin scales in the Naqu River Basin of the TP. The results show that Tropical Rainfall Measuring Mission (TRMM) precipitation overestimated the precipitation with BIAS of 0.2; the intensity distributions of daily precipitation are consistent in the two precipitation data. TRMM precipitation was then corrected by the good linear relation between monthly areal TRMM precipitation and gauge precipitation, and applied into the Water and Energy Process model. The results indicate that the simulated streamflow using both precipitation data produce a good fit with observed streamflow, especially at monthly scale. Furthermore, the better relations between average slopes and runoff coefficients of sub-basins from the corrected TRMM precipitation-based model implies that the spatial distribution of TRMM precipitation is closer to the spatial distribution of actual precipitation, and has an advantage in driving distributed hydrological models. [ABSTRACT FROM AUTHOR]