Hydro-Chemical Processes in Lake Qinghai throughout Climate Warming: In Situ Investigations of the Largest Lake in China

In the wake of climate warming, the water level of Lake Qinghai has been continuously and rapidly declining during the past decades, causing the regional government and citizens to worry about its future as a water resource. To understand the lake evolution process, the hydro-chemical characteristics of Lake Qinghai were investigated in August of 2008. The results show that Na+ and Cl- are the dominant cations and anions in the lake water, respectively, and hydrochemistry type is Cl-- Na+ with an obvious characteristic of a saline lake. The Gibbs plot illuminates that evaporation/crystallization is responsible for the chemical composition of the lake water. The variation in hydro-chemical regime might be attributed to the reduced lake levels between 1960s and 2000s. The lake level significantly correlated with the precipitation and evaporation in the Lake Qinghai catchment. In addition, changes of the lake level in the future are simulated according to climate warming scenarios from the IPCC report. The simulated results suggest that the lake level could rise again in the following decades due to the increased precipitation under the climate warming conditions, which is already a trend in the lake level observation data.

Research on Greenway Route Selection of Traditional Villages Based on GIS: A Case Study of Xingtai County, China

Greenway is a green linear corridor connecting scenic spots, residential areas, nature reserves, road traffic, etc. Rational greenway route selection can not only attract tourists to increase the income of local villages, but also arouse people’s awareness of the protection of traditional villages. This paper took Xingtai County, Hebei Province, China as an example to practice greenway route selection in the county territory. Eight factors were selected for greenway route planning, namely elevation, water body, mountain, ecological protection redline, cultural relics protection units, population density, road traffic network, and important transportation hub. These eight factors were assigned in the GIS platform, and the suitability evaluation system of each factor was constructed. The analytic hierarchy process (AHP) and entropy weight method were combined to calculate the weight of these eight factors. The raster calculator was used to weight and overlay the suitability evaluation system of each factor, and the comprehensive suitability evaluation map of greenway route selection was obtained. Based on an important transport hub, along with the water body and the road traffic, the final selection greenway route of traditional villages in Xingtai county was formed. The results of the research can provide a certain reference for the greenway route selection at the county scale.

Lacustrine record of 800 yr hydrological variations on the central Tibetan Plateau

Zige Tangco is a meromictic saline lake located on the central Tibetan Plateau.Two parallel cores(ZGTC A-1 and ZGTC A-2)were collected from the lake at a water depth of 25 m during summer 2006.The chronology of core A-1 was reconstructed based on the Constant Initial Concentration(CIC)model of 210Pb and three accelerator mass spectrometry(AMS)ages from the chitin fragments.The hard water effect calibration of the sediment ^(14)C age showed that the reservoir effect ranged from 1655 yr at 1950 AD to 1540 yr at 1610 AD.The hydrological variation in Zige Tangco during the past 800 yr was reconstructed using multi-proxies,including organic and carbonate content,stable isotopes of fine-grained carbonate minerals(<38.5μm)and grain-size distribution of the lake sediments.Our results show that there were strong fluctuations in the lake level between 1200 and 1820 AD,and at least three dry periods were recorded between 1235 and 1315 AD,1410 and 1580 AD,and 1660 and 1720 AD characterized by high carbonate content,abrupt positive shifts of stable isotopes,and high sand content.The low-lake-level periods during the Little Ice Age(LIA)in Zige Tangco correspond to the lower δ^(18)O values in the Guliya ice core and the lower precipitation reconstructed from tree rings in Delingha.This demonstrated that the summer monsoon on the central Tibetan Plateau weakened during the dry and cold periods,whereas the winter monsoon strengthened.Relatively wetter periods or higher lake levels in Zige Tangco occurred at 1580-1650 AD and 1820-1900 AD.Negative shifts in stable isotopes were related to increased lake levels between 1800 and 1820 AD.Our results also showed that the summer monsoon precipitation on the central Tibetan Plateau was mainly controlled by solar activity during the past 800 yr.