Simulation and analysis of river runoff in typical cold regions

It is generally agreed that global warming is taking place, which has caused runoff generation processes and apparently total runoff amount changes in cold regions of Northwestern China. It is absolutely necessary to quantify and analyze earth surface hydrolog- ical processes by numerical models for formulating scientific sustainable development of water resources. Hydrological models became established tools for studying the hydrological cycle, but did not consider frozen soil or glacier hydrology. Thus, they should be improved to satisfy the simulation of hydrological processes in cold regions. In this paper, an energy balance glacier melt model was successfully coupled to the VIC model with frozen soil scheme, thus improving the models performance in a cold catchment area. We performed the improved VIC model to simulate the hydrological processes in the Aksu River Basin, and the simulated results are in good agreement with observed data. Based on modeling hydrological data, the runoff components and their response to climate change were analyzed. The results show： （1） Glacial meltwater recharge accounts fbr 29.2% of runoff for the Toxkan River, and 58.7% for the Kunma Like River. （2） The annual total runoffoftwo branches of the Aksu River show in- creasing trends, increased by about 43.1%, 25.75 X 106 m3 per year for the Toxkan River and by 13.1%, 14.09 ~ l06 m3 per year for the Kunma Like River during the latter 38 years. （3） The annual total runoff of the Toxkan River increased simply due to the increase of non-glacial runoff, while the increase of annual total runoff of the Kunma Like River was the result of increasing gla- cial （42%） and non-glacial runoff （58%）.

Water resources response and prediction under climate change in Tao'er River Basin,Northeast China

Climate change has significantly affected hydrological processes and increased the frequency and severity of water shortage,droughts and floods in northeast China.A study has been conducted to quantify the influence of climate change on the hydrologic process in the Tao’er River Basin(TRB),one of the most prominent regions in northeast China for water contradiction.The Soil and Water Assessment Tool(SWAT)model was calibrated and validated with observed land use and hydro-climatic data and then employed for runoff simulations at upper,middle and lower reaches of the river basin for different climate change scenarios.The results showed that a gradual increase in temperature and decrease in annual precipitation in the basin was projected for the period 2020-2050 for both representative concentration pathways(RCP)4.5 and 8.5 scenarios.The climate changes would cause a decrease in annual average runoff at basin outlet by 12 and 23 million m^(3) for RCP4.5 and 8.5,respectively.The future runoff in the upstream and midstream of the basin during 2020-2050 would be-10.8% and-12.1% lower than the observed runoff compared to the base period for RCP4.5,while those would be-5.3% and-10.7%lower for RCP8.5.The future runoff will decrease at three hydrology stations for the assumed future climate scenarios.The results can help us understand the future temperature and precipitation trends and the hydrological cycle process under different climate change scenarios,and provide the basis for the rational allocation and management of water resources under the influence of future climate change in the TRB.

Quantitative assessment on basin-scale hydrological services of wetlands

Despite recognizing the importance of hydrological function of wetlands, basin-scale wetlands services have rarely been investigated. The PHYSITEL/HYDROTEL modelling platform was used to quantitatively assess the impact of wetlands on quickflow and baseflow with paired simulation scenarios in Duobukuli River Basin, namely with wetlands and without wetlands.Simulation results showed that wetlands exert significant impact on basin hydrological processes by decreasing streamflow and altering streamflow regime(magnitude, frequency, duration and time of flow events). The intensity(significant or not) of wetlands influences on quickflow had daily, monthly and annual variation. Wetlands significantly attenuated quickflow during flood season while slightly support daily, monthly and annual baseflow. The average quickflow attenuation and baseflow support of wetlands were 5.89% and 0.83%, respectively. Although the intensity and effect(mitigation or augment) of wetlands on streamflow temporally varied at daily, monthly, seasonal and annual scales, wetland overall mitigated quickflow and augment baseflow in Duobukuli River Basin. Our results could provide insights for future decision-making for rehabilitation and conservation of wetlands as well as integrated basin water resources management.