Understanding the impact of mountain landscapes on water balance in the upper Heihe River watershed in northwestern China

Estimating the impact of mountain landscape on hydrology or water balance is essential for the sus- tainable development strategies of water resources. Specifically, understanding how the change of each landscape influences hydrological components will greatly improve the predictability of hydrological responses to mountain landscape changes and thus can help the government make sounder decisions. In the paper, we used the VIC （Variable Infiltration Capacity） model to conduct hydrological modeling in the upper Heihe River watershed, along with a frozen-soil module and a glacier melting module to improve the simulation. The improved model performed satisfactorily. We concluded that there are differences in the runoff generation of mountain landscape both in space and time. About 50% of the total runoff at the catchment outlet were generated in mid-mountain zone （2,900-4,000 m asl）, and water was mainly consumed in low mountain region （1,700-2,900 m asl） because of the higher requirements of trees and grasses. The runoff coefficient was 0.37 in the upper Heihe River watershed. Barren landscape produced the largest runoff yields （52.46% of the total runoff） in the upper Heihe River watershed, fol- lowed by grassland （34.15%）, shrub （9.02%）, glacier （3.57%）, and forest （0.49%）. In order to simulate the impact of landscape change on hydrological components, three landscape change scenarios were designed in the study. Scenario 1, 2 and 3 were to convert all shady slope landscapes at 2,000-3,300 m, 2,000-3,700 m, and 2,000-4,000 m asl respectively to forest lands, with forest coverage rate increased to 12.4%, 28.5% and 42.0%, respectively. The runoff at the catchment outlet correspondingly declined by 3.5%, 13.1% and 24.2% under the three scenarios. The forest landscape is very important in water conservation as it reduced the flood peak and increased the base flow. The mountains as ＂water towers＂ play important roles in water resources generation and the impact of mountain landscapes on hydrology is significant.

A review of the interaction between the cryosphere and atmosphere

The interaction between the cryosphere and atmosphere is an essential and extremely sensitive mutual action process on the earth.Due to global warming and the cryospheric melting,more and more attention has been paid to the interaction process between the cryosphere and atmosphere,especially the feedback of the cryosphere change to the atmosphere.A comprehensive review of the studies on the interaction between the cryosphere and atmosphere is conducted from two aspects:(1)effects of climate change on the cryosphere or responses of the cryosphere to climate change;and(2)feedback of the cryosphere change to the climate.The response of the cryosphere to climate change is lagging.Such a lagging and cumulative effect of temperature rise within the cryosphere have resulted in a rapid change in the cryosphere in the 21st century,and its impacts have become more significant.The feedback from cryosphere change on the climate are omnifarious.Among them,the effects of sea ice loss and snow cover change,especially the Arctic sea ice loss and the Northern Hemisphere snow cover change,are the most prominent.The Arctic amplification(AA)associated with sea ice feedback is disturbing,and the feedback generated by the effect of temperature rise on snow properties in the Northern Hemisphere is also of great concern.There are growing evidence of the impact of the Arctic cryosphere melting on mid-latitude weather and climate.Weakened storm troughs,steered jet stream and amplified planetary waves associated with energy propagation become the key to explaining the links between Arctic cryosphere change and atmospheric circulation.There is still a great deal of uncertainty about how cryosphere change affects the weather and climate through different atmospheric circulation processes at different spatial and temporal scales due to observation and simulation problems.

Influences of two patterns of El Ni o on hydrological and meteorological elements in the Hexi Corridor region of China

In this study, two types of E1 Nifio events are distinguished and the correlations between the respective precipitation, temperature, and runoff are analyzed by a 5-point moving average method. Also, changes of the temperature, precipitation, and runoff from mountainous watersheds of the Hexi Corridor region caused by these two types of E1 Nifio events from 1959 to 2005 are studied by the anomaly analysis method. The results indicate that the Hexi Corridor region is strongly influenced by El Nifio： rising tem- peratures and decreasing precipitation and runoff are features of the first E1 Nifio pattern, while decreasing temperature and in- creasing precipitation and runoff characterise the second pattern. The responses of temperature to E1 Nifio events are stronger in plains than in mountain regions, but the responses of precipitation are obvious in both types of regions. The response of runoff to E1 Nifio events is lower than the precipitation and temperature response because runoff from mountainous watersheds has a com- plex generation and concenlration process.