Simulation of hydrological processes of mountainous watersheds in inland river basins: taking the Heihe Mainstream River as an example

The hydrological processes of mountainous watersheds in inland river basins are complicated.It is absolutely significant to quantify mountainous runoff for social,economic and ecological purposes.This paper takes the mountainous watershed of the Heihe Mainstream River as a study area to simulate the hydrological processes of mountainous watersheds in inland river basins by using the soil and water assessment tool(SWAT)model.SWAT simulation results show that both the Nash–Sutcliffe efficiency and the determination coefficient values of the calibration period(January 1995 to December 2002)and validation period(January 2002 to December 2009)are higher than 0.90,and the percent bias is controlled within±5%,indicating that the simulation results are satisfactory.According to the SWAT performance,we discussed the yearly and monthly variation trends of the mountainous runoff and the runoff components.The results show that from 1996 to 2009,an indistinctive rising trend was observed for the yearly mountainous runoff,which is mainly recharged by lateral flow,and followed by shallow groundwater runoff and surface runoff.The monthly variation demonstrates that the mountainous runoff decreases slightly from May to July,contrary to other months.The mountainous runoff is mainly recharged by shallow groundwater runoff in January,February,and from October to December,by surface runoff in March and April,and by lateral flow from May to September.

The heterogeneity of hydrometeorological changes during the period of 1961-2016 in the source region of the Yellow River, China

Runoff in the source region of a river makes up most of water resources in the whole basin in arid and semi-arid areas. It is very important for water resources management to timely master the latest dynamic changes of the runoff and quantitatively reveal its main driving factors. This paper aims to discover the variation heterogeneity of runoff and the impacts of climatic factors on this runoff in the source region of the Yellow River(SRYR) in China from 1961 to 2016. We divided SRYR into four sub-regions, and analyzed changes of their contributions to total runoff in SRYR. We also revealed the impacts of precipitation, temperature and potential evapotranspiration on runoff in each sub-region by constructing the regression relationships between them at multiple temporal scales. The changes of runoff in the four sub-regions and their contributions to the total runoff were not exactly consistent. The climatic variables’ changes also have heterogeneity, and runoff was mainly affected by precipitation compared to influences of temperature or potential evapotranspiration. Their impacts on runoff have spatiotemporal heterogeneity and can be reflected by very significant-linear regression equations.It provided a simple method to predict headwater runoff for better water management in the whole basin.

Study of temperature and precipitation change in upstream mountain area of the Hexi inland river basin since 1960s

All rivers in the Hexi inland region of Gansu Province, China, originate from the northern slope of the Qilian Mountains. They are located in the southern portion of the region and respectively belong to the three large river systems from east to west, the Shiyang, Heihe and Shule river basins. These rivers are supplied by precipitation, snowmelt and ice-melt runoff from the Qilian Mountain area. Therefore, changes of precipitation and temperature in the upstream watersheds of these rivers have an important effect on changes of mountainous runoff and reasonable utilization of water resources in this region. For this reason, the Qilian Mountain area, upstream watersheds and runoff forming areas of these rivers are chosen as the study area. The change characteristics and variation trend of temperature and precipitation in this area under the backdrop of global warming axe analyzed based on observa- tional data of relational weather and hydrologic stations in the area. Results show that temperatures in the upriver mountain areas of these three large river basins have been increasing, although the increasing degree is differentially affected by global warming. The rising extent of annual and seasonal temperatures in the upstream mountain area of the Shule river basin located in the west- em Qilian Mountains, were all largest over the past 50 years. Precipitation in the upstream mountain areas of Hexi region＇ three river basins located respectively in the western, middle and eastern Qilian Mountains have been presenting an increasing trend to varying degrees as a whole for more than 50 years. This means that climate in the upstream mountain areas of Hexi region＇ three river basins are becoming increasingly warmer and moister over the past 50 years, which will be very good for the ecological en- vironment and agricultural production in the region.

An analysis on ecological civilization construction in Gansu based on a quantified SWOT framework

Ecological civilization （EC） construction has become one of the key elements of China＇s reform and development process, since it was put forward at the 17th National People＇s Congress （NPC） in 2007 and improved at the 18th NPC in 2012, and stressed at the third plenary session of the 18th NPC. The provincial areas are the most important pilot units of EC strategy. Therefore, research on EC at the provincial level can meet the practical demand for EC in China. Based on the existing provincial circumstances in Gansu and its significant position as an ecological barrier in northwestern China, and aiming at the core issue of why and how to build EC in Gansu, this paper employs SWOT （strengths, weaknesses, opportunities, threats） analysis, the Delphi method, and a combined quantitative analysis and coordinate method, and then calculates the relevant strategic orientation angle （0 = 1.4605） and strength coefficient （p = 0.53）. The results show that Gansu should take an opportunities-dominated strategy, and choose opportunity-strength measures, so the province can increase its in- ternal strengths and decrease its weaknesses with external promote an EC construction strategy. opportunities. Specific measures are recommended to actively

中国北方干旱半干旱区植被-气候响应关系特征

气候变化背景下干旱区植被的时空分布及变化特征,是区域植被恢复和国家自然保护区建设等亟需研究的关键生态环境问题。在建立中国北方干旱半干旱区潜在植被分类及对Holdridge生命地带模型进行修正和拓展的基础上,结合中国气象模拟数据(1981—2020年),引入植被面积转移矩阵、Kappa系数和平均中心模型等方法,对中国北方干旱半干旱区气候要素进行分析并实现了潜在植被定量识别和空间分布格局模拟。结果显示:40年间年降水量、年平均生物温度和可能蒸散率总体均呈上升趋势,研究区存在暖干化现象;研究区共出现6种潜在植被类型,在不同年代际均呈地带性分布;温带荒漠植被、温带草本植被和温带森林植被是主要植被类型,共占总覆盖面积约71%;温带森林植被的面积总体增长最快,平均每10年增加1.1%,温带荒漠植被减少最快,平均每10年减少1.3%;相邻年代际间,各类潜在植被的面积转换关系较为稳定,差别在于转换程度;山地森林植被、温带荒漠植被和温带森林植被的平均中心总体偏移距离大于50 km,除温带荒漠植被,其他植被的平均中心总体均往西移。

祁连山绿色发展:从生态治理到生态恢复

在祁连山生态环境经重锤整治、生态恢复初显成效之际,第二次青藏高原综合科学考察之'祁连山综合考察'全面开启.优先围绕生态系统与生态安全、固体水库动态变化、人类活动变化与生态生计影响三大关键任务,开展天-空-地一体化考察,定量核算了生态环境整治后局部的生态环境收益与经济损失,并基于远程耦合方法核算了祁连山的全局生态系统服务价值.研究发现:生态环境整治提升了生态环境服务价值;暖湿化背景下生态系统整体向好,珍稀物种种群扩大,但对局部草原过牧管控不力导致退化;冰川冰储量亏损加剧,冰川融水径流贡献率将越过临界点;过去10多年冻土融化释放的水量约为1.18 km3/a,相当于祁连山出山河流年径流总量的10%;祁连山全局生态系统服务估算价值高达10676(±1601)亿元,远高于2017年区域经济损失的53.09亿元.鉴于祁连山对于全国的巨大生态价值,建议国家加大生态补偿力度,实现祁连山生态生计双赢的绿色发展.祁连山综合科学考察成果可为祁连山国家公园建设,以及'山水林田湖草'系统保护与修复提供详实数据和决策依据,为'丝绸之路经济带'沿线国家流域治理提供典型案例和科学支撑.