Using the combined methods of digital image processing of remote sensing data, a Geographical Information System (GIS) and analysis of historical books and maps, this paper aims to contribute to a better understanding of the processes and mechanisms of land-use and land-cover changes and hydrological variations during the last 2000 years in a hyper-arid environment. The southern and eastern Taklamakan Desert, one of the driest and ecologically most sensitive regions in China and characterized by a long history of human settlements, was chosen as the study area. A hydrological connection between the Keriya and Niya rivers in former times was recognized for the first time using satellite imagery. After transferring the notes and maps of historical times into a simplified modern map, it shows that the Lop Nuer decreased in size from a large lake in the Han Dynasty (206 BC to AD 220) to a much smaller one in the Qing Dynasty (AD 1644(AD -1911. Areas settled in former times differ morphologically from the dune landscape in satellite imagery because of flat relief along dried river courses. A review of archaeological literature reinforces the fact that in the lower reaches of the Keriya and Niya rivers, in the interior of the Taklamakan Desert, irrigated agriculture was widely practised from ca. 200 BC to ca. AD 500. A possible climatic change toward drier conditions at ca. AD 500 is suggested as the cause of the abandonment of the cities in the desert and for the initial drying of the formerly large Lop Nuer Lake. flat, and would be suitable for agricultural production if there was water. Therefore, the satellite images can help archaeologists select sites of interests. Conversely, the archeological discoveries reconfirm that these areas were used for agriculture in the past. The Sino-French Expedition Team (1997) systematically excavated the ruined settlement Yuansha (Figures 4 and 5A) and found that Yuansha was constructed in the form of an old Chinese city. This archeological team unearthed an urbanized city marked by a 3-4 m high, ca. 1 km long and quasi-round wall. The team also found grains, irrigation channels and bones of household animals. It was concluded that both crop cultivation and animal grazing were significant in the lower reaches of the Keriya River ca. 2000 years ago. The Figure 7. River nets and lakes in southern and eastern Tarim Basin during the Han Dynasty (A) and the Qing Dynasty (B) according to historical books and maps. The geographical names are from former times and can be quite different from present ones.

Cryospheric changes have great effects on alpine hydrology, but these effects are still unclear owing to rare observations and suitable models in the western cold regions of China. Based on long‐term field observations in the western cold regions of China, a cryospheric basin hydrological model was proposed to evaluate the cryospheric effects on streamflow in the upper Hei River basin (UHR), and the relationship between the cryosphere and streamflow was further discussed with measured data. The Norwegian Earth System Model outputs were chosen to project future streamflow under scenarios Representative Concentration Pathways (RCP)2.6, RCP4.5, and RCP8.5. The cryospheric basin hydrological model results were well validated by the measured precipitation, streamflow, evapotranspiration, soil temperature, glacier and snow cover area, and the water balance of land cover in the UHR. The moraine‐talus region contributed most of the runoff (60%), even though it made up only about 20% of the area. On average, glacier and snow cover, respectively, contributed 3.5% and 25.4% of the fresh water to the streamflow in the UHR between 1960 and 2013. Because of the increased air temperature (2.9°C/54a) and precipitation (69.2 mm/54a) over the past 54 years, glacial and snowmelt runoff increased by 9.8% and 12.1%, respectively. The increase in air temperature brought forward the snowmelt flood peak and increased the winter flow due to permafrost degradation. Glaciers may disappear in the near future because of their small size, but snowmelt would increase due to increases in snowfall in the higher mountainous areas, and the basin runoff would increase slightly in the future.

Abstract. An experimental field study of wind-induced bias in precipitation measurements was conducted from September 2010 to April 2015 at a grassland site (99°52.9´ E, 38°16.1´ N; 2980 m) in the Hulu watershed in the Qilian Mountains, on the north-eastern Tibetan Plateau, in China. The experiment included (1) an unshielded Chinese standard precipitation gauge (CSPGUN; orifice diameter = 20 cm, height = 70 cm), (2) a single Alter shield around a CSPG (CSPGSA), (3) a CSPG in a pit (CSPGPIT) and (4) a Double-Fence International Reference (DFIR) with a Tretyakov-shielded CSPG (CSPGDFIR). The catch ratio (CR) used the CSPGDFIR as a reference (CR = CSPGX/CSPGDFIR, %; X denotes UN, SA or PIT). The results show that the CSPGSA, CSPGPIT and CSPGDIFR caught 0.9, 4.5 and 3.4 % more rainfall; 7.7, 15.6 and 14.2 % more mixed precipitation (snow with rain, rain with snow); 11.1, 16.0 and 20.6 % more snowfall and 2.0, 6.0 and 5.3 % more precipitation (of all types), respectively, than the CSPGUN from September 2012 to April 2015. The CSPGPIT and CSPGDFIR caught 3.6 and 2.5 % more rainfall; 7.3 and 6.0 % more mixed precipitation; 4.4 and 8.5 % more snowfall; and 3.9 and 3.2 % more total precipitation, respectively, than the CSPGSA. However, the CSPGDFIR caught 1.0 % less rainfall; 1.2 % less mixed precipitation; 3.9 % more snowfall and 0.6 % less total precipitation than the CSPGPIT. From most to least precipitation measured, the instruments ranked as follows: for rain and mixed precipitation, CSPGPIT > CSPGDFIR > CSPGSA > CSPGUN; for snowfall, CSPGDFIR > CSPGPIT > CSPGSA > CSPGUN. The CR vs. 10 m wind speed for the period of precipitation indicated that with increasing wind speed from 0 to 8.0 m s−1, the CRUN/DFIR and CRSA/DFIR for rainfall decreased slightly. For mixed precipitation, the wind speed showed no significant effect on CRUN/DFIR and CRSA/DFIR below 3.5 m s−1. For snowfall, the CRUN/DFIR and CRSA/DFIR vs. wind speed showed that CR decreased with increasing wind speed. The precipitation measured by the shielded gauges increased linearly relative to that of the unshielded gauges. However, the increase in the ratio of the linear correlation should depend on specific environmental conditions. A comparison of the wind-induced bias indicates that the CSPGPIT could be used as a reference gauge for rain, mixed and snow precipitation events at the experimental site. As both the PIT and DFIR effectively prevented wind from influencing the catch of the precipitation gauge, the CRPIT/DFIR had no relationship with wind speed. Cubic polynomials and exponential functions were used to quantify the relationship between catch ratio and wind speed. For snow, for both event and daily scales, the CRUN/DFIR and CRSA/DFIR were significantly related to wind speed; while for rain and mixed precipitation, only the event scale showed a significant relationship.