Ecological Network Resilience of Shiyang River Basin: An Arid Inland Watershed of Northwest China

Due to the uncertainties posed by climate change,resilience has become an increasingly important variable for evaluating regional ecosystem stability.The assessment of Ecological Network Resilience(ENR)is crucial for establishing mitigation strategies and sustainable socioeconomic development in arid regions.Shiyang River Basin is an arid watershed in Northwest China with complex characteristics,its ENR and spatial differentiation characteristics in 2020 were investigated in this work based on the Complex Adaptive System(CAS)theory.The results indicated that the mean Ecological Network Resilience Index(ENRI)value for the Shiyang River Basin was 0.390 in 2020,and the mean values in the southern mountainous,middle oasis,and northern desert regions of the basin were 0.598,0.461,and 0.237,respectively,demonstrating evident spatial differences.Additionally,the ENR of the basin exhibited distinct distribution characteristics across different dimension,whereas the trend of the integrated ENR of the basin was consistent with that of elemental,structural,and functional resilience,indicating the constructed three-region ENR model based on the logical relationship of element-structure-function was suitable for evaluation of the ENR in arid inland river watersheds.Furthermore,strategies for enhancing regional ENR were proposed from the perspective of adapting to climate change.

Response of vegetation variation to climate change and human activities in the Shiyang River Basin of China during 2001-2022

Understanding the response of vegetation variation to climate change and human activities is critical for addressing future conflicts between humans and the environment,and maintaining ecosystem stability.Here,we aimed to identify the determining factors of vegetation variation and explore the sensitivity of vegetation to temperature(SVT)and the sensitivity of vegetation to precipitation(SVP)in the Shiyang River Basin(SYRB)of China during 2001-2022.The climate data from climatic research unit(CRU),vegetation index data from Moderate Resolution Imaging Spectroradiometer(MODIS),and land use data from Landsat images were used to analyze the spatial-temporal changes in vegetation indices,climate,and land use in the SYRB and its sub-basins(i.e.,upstream,midstream,and downstream basins)during 2001-2022.Linear regression analysis and correlation analysis were used to explore the SVT and SVP,revealing the driving factors of vegetation variation.Significant increasing trends(P<0.05)were detected for the enhanced vegetation index(EVI)and normalized difference vegetation index(NDVI)in the SYRB during 2001-2022,with most regions(84%)experiencing significant variation in vegetation,and land use change was determined as the dominant factor of vegetation variation.Non-significant decreasing trends were detected in the SVT and SVP of the SYRB during 2001-2022.There were spatial differences in vegetation variation,SVT,and SVP.Although NDVI and EVI exhibited increasing trends in the upstream,midstream,and downstream basins,the change slope in the downstream basin was lower than those in the upstream and midstream basins,the SVT in the upstream basin was higher than those in the midstream and downstream basins,and the SVP in the downstream basin was lower than those in the upstream and midstream basins.Temperature and precipitation changes controlled vegetation variation in the upstream and midstream basins while human activities(land use change)dominated vegetation variation in the downstream basin.We concluded that there is a spatial heterogeneity in the response of vegetation variation to climate change and human activities across different sub-basins of the SYRB.These findings can enhance our understanding of the relationship among vegetation variation,climate change,and human activities,and provide a reference for addressing future conflicts between humans and the environment in the arid inland river basins.

Land use and cover change and influencing factor analysis in the Shiyang River Basin,China

Land use and cover change(LUCC)is the most direct manifestation of the interaction between anthropological activities and the natural environment on Earth's surface,with significant impacts on the environment and social economy.Rapid economic development and climate change have resulted in significant changes in land use and cover.The Shiyang River Basin,located in the eastern part of the Hexi Corridor in China,has undergone significant climate change and LUCC over the past few decades.In this study,we used the random forest classification to obtain the land use and cover datasets of the Shiyang River Basin in 1991,1995,2000,2005,2010,2015,and 2020 based on Landsat images.We validated the land use and cover data in 2015 from the random forest classification results(this study),the high-resolution dataset of annual global land cover from 2000 to 2015(AGLC-2000-2015),the global 30 m land cover classification with a fine classification system(GLC_FCS30),and the first Landsat-derived annual China Land Cover Dataset(CLCD)against ground-truth classification results to evaluate the accuracy of the classification results in this study.Furthermore,we explored and compared the spatiotemporal patterns of LUCC in the upper,middle,and lower reaches of the Shiyang River Basin over the past 30 years,and employed the random forest importance ranking method to analyze the influencing factors of LUCC based on natural(evapotranspiration,precipitation,temperature,and surface soil moisture)and anthropogenic(nighttime light,gross domestic product(GDP),and population)factors.The results indicated that the random forest classification results for land use and cover in the Shiyang River Basin in 2015 outperformed the AGLC-2000-2015,GLC_FCS30,and CLCD datasets in both overall and partial validations.Moreover,the classification results in this study exhibited a high level of agreement with the ground truth features.From 1991 to 2020,the area of bare land exhibited a decreasing trend,with changes primarily occurring in the middle and lower reaches of the basin.The area of grassland initially decreased and then increased,with changes occurring mainly in the upper and middle reaches of the basin.In contrast,the area of cropland initially increased and then decreased,with changes occurring in the middle and lower reaches.The LUCC was influenced by both natural and anthropogenic factors.Climatic factors and population contributed significantly to LUCC,and the importance values of evapotranspiration,precipitation,temperature,and population were 22.12%,32.41%,21.89%,and 19.65%,respectively.Moreover,policy interventions also played an important role.Land use and cover in the Shiyang River Basin exhibited fluctuating changes over the past 30 years,with the ecological environment improving in the last 10 years.This suggests that governance efforts in the study area have had some effects,and the government can continue to move in this direction in the future.The findings can provide crucial insights for related research and regional sustainable development in the Shiyang River Basin and other similar arid and semi-arid areas.

Change Characteristics of Climate and Main Agricultural Meteorological Disasters in Shiyang River Basin

Based on 35 a meteorological data and main crops planting data in Shiyang River basin meteorological station,the agricultural climate change,agricultural production,hydrology change and the influences on the crops layout,planting in the basin were discussed.The results showed that the linear inclined rates of ≥0 ℃,10 ℃ accumulated temperature increase in the north-central part were bigger than in the south,and the heat resources increased evidently.The annual precipitation increased in the linear inclined rate which was 4.719 mm/10 a,and the annual runoff decreased in 0.274×109 m3/10 a velocity.The climate productivity increased in 134.62 kg/(hm2·10 a) velocity.In late spring and early summer,the regional drought increased evidently,and the frostless period prolonged.The sand storm decreased evidently.The gale in the south increased and decreased in the north-central part.The agricultural climate change made that the spring wheat planting zone advanced to the high-altitude area.The seeding date advanced,and the growth period shortened.It didn't favor for the yield formation.However,it was favorable to improve the yield and quality of thermophilous crops such as the corn,cotton and wine grape and so on.

Evaluation of oasis ecosystem risk by reliability theory in an arid area: A case study in the Shiyang River Basin, China

Ecosystem risk is a new concept in understanding environmental problems. It is important to study and develop quantitative methods for regional ecosystem risk analysis. In this study, some new indicators and methods for measuring oasis ecosystem risk were established using reliability theory. These indicators are linked to water resource, which is the key restricting factor in arid area oasis ecosystems. They have clear meanings and can also be compared in different arid area oases. A case study in the Liangzhou oasis of the Shiyang River Basin in China shows how to calculate these ecosystem risk indicators. The results of the case study are as follows： the reliability indicator, risk indicator, stability indicator, and integrated loss indicator of the Liangzhou oasis are 0.686, 0.314, 0.743, and 0.301, respectively. This means that the reliability degree of the oasis＇s ecosystem safety is 68.6%; the degree of risk that it is unsafe is 31.4%; the stability degree is 74.3%; and 30.1% of the oasis＇s area is supported by over-exploiting underground water and damaging the lower reaches of the ecosystem. This result can be used as a guide in controlling and managing ecosystem risk in the research area.

Glacial Runoff Likely Reached Peak in the Mountainous Areas of the Shiyang River Basin,China

Glacier runoff in mountain areas of the Shiyang River Basin(SRB), Qilian Mountain, western China is important for the river and water supply downstream. Small glaciers with area of less than 1km2 are dominant(87%) in the SRB. A modified monthly degree-day model was applied to quantify the glacier mass balance, area, and changes in glacier runoff in the SRB during 1961–2050. The comparison between the simulated and observed snow line altitude, annual glacier runoff, and mass balance from1961 to 2008 suggests that the degree-day model may be used to analyze the long-term change of glacier mass balance and runoff in the SRB. The glacier accumulation shows a significant(p<0.01) decreasing trend of-0.830 mm a-1. The mass balance also shows a significant(p<0.01) decreasing trend of-5.521 mm a-1. The glacier total runoff has significantly(p<0.05)increased by 0.079 × 105 m3 from 1961 to 2008. The monthly precipitation and air temperature are projected to significant(p<0.005) increase during2015 to 2050 under three different scenarios. The ablation is projected to significant(p<0.001) increase,while the accumulation has no significant(p=0.05)trend. The mass balance is projected to decrease, theglacier area is projected to decrease, and the glacier runoff depth is projected to increase. However, the glacier total runoff is projected to decrease. These results indicate that the glacier total runoff over glacier areas observed in 1970 reached its peak in the 2000 s. This will exacerbate the contradiction between water supply and downstream water demands in the SRB.

SAFETY ANALYSIS OF WATER RESOURCES AND ECO-ENVIRONMENT IN SHIYANG RIVER BASIN

The research on the present situation of soil and water development and utilization in Shiyang River Basin shows that water resources and eco-environment situation in this area are near the edge of collapse. Since the water crises occurred in the 1970s, problems caused by continuous decrease of water resources have been becoming serious year by year and eco-environment crisis occurred as a consequence. Up to now, 10 380ha of irrigated lands have been abandoned due to sand coverage and water shortage in the basin. Ground water was over exploded in Wuwei and Minqin because of water shortage. Ground water table in many places dropped under 5m （which is the ecology water table level）, thus about 3000ha ofElaeagnus angustifolia forest come to dead and another 5800ha become feeble, and wind-drift sand near the oasis become alive. According to the current situation, if water utilization scope was not enlarged, a water transfer volume of 600×10^6m^3/a from other areas will be suitable to keep water resources and eco-environment safety in the basin, and also 70×10^6m^3/a will be left as spare water. Under this condition the water resources and eco-environment of the basin can reach the critical safety line of 2.032×10^6m^3/a; or if 180×10^6m^3 of water can be transferred from other areas, the water resources can reach the safety warning line of 1.732×10^9m^3/a.

Mapping the dynamic degree of aeolian desertification in the Shiyang River Basin from 1975 to 2010

The Shiyang River Basin is an area of China that is severly affected by aeolian desertification.Thus,we established an aeolian desertified land classification system for visual interpretation,which classified the Aeolian Desertified Land(ADL)into Slight(SL),Moderate(M),Severe(S)and Extremely Severe(ES)according to the severity.Imagery of Landsat series(acquired in 1975,1990,2000 and 2010)were employed to monitor the status,trend and spatial pattern of aeolian desertification,especially to map the overall spatial pattern of ADL dynamics by proposing a new Dynamic Index(DI)in the Shiyang River Basin from 1975 to 2010.The results show a generally decreasing trend from 1975 to 2010.However,the ES ADL kept increasing throughout the whole study period.Moreover,the area of ADLs with different severity increased with increasing severity,this S and ES ADLs dominated characteristics of aeolian desertification was contrary to those sandy lands in eastern China where was dominated by SL and M ADLs.Among the three sub-periods of 1975−1990,1990−2000 and 2000−2010,the first two were the restoration stage,while the last one was the expansion stage of aeolian desertification.Moreover,all these new ADLs occurred in Minqin County during 2000−2010,indicating a detrimental increase of aeolian desertification in Minqin,and the concentration of ADLs toward the lower reaches of the Shiyang River Basin.The DI works well to identify areas with desertification changes no matter the sub-periods.Moreover,DI results disclosed a stable status of aeolian desertification,and the DI decreased with increasing ADL severity.These results indicate that it will be difficult to control the expansion of aeolian desertification in Minqin County over an extended period of time.Thus,we suggest effective and long-lasting aeolian desertification control programs in the Shiyang River Basin,especially in Minqin,and SL and MADLs should have priority in facilitating a quick reversal of aeolian desertification.

Response Characteristics of Climate in the Shiyang River Basin to Global Warming

Meteorological data of 5 weather stations in the Shiyang River Basin on the eastern section of Hexi Corridor from 1961 to 2014 were analyzed using statistical analysis techniques such as linear trend and variance signifi cance test. The results showed that as the low temperature rose generally, temperature in stations nearby desert showed higher increase rate; annual extreme maximum temperature in stations nearby mountains showed more signifi cant increase, and annual extreme minimum temperature in stations nearby desert showed more signifi cant increase, and the increase tendency of extreme minimum temperature was more obvious than that of extreme maximum temperature; annual extreme maximum temperature in stations in desert showed higher instability; instability of annual extreme minimum temperature in all sampling points increased, and showed no obvious regularity between desert and mountain.

AREAL DIFFERENTIATION AND CONSTRUCTION OF OASIS AGRICULTURAL ECOSYSTEM IN THE SHIYANG RIVER BASIN

On the basis of the study on areal differentiation of the natural environment of oasis agriculture ecosystems in the Shiyang River Basin, this paper comparatively analyzes the natural productivities, water economic benefits, production efficiency, ecological stabilities and developmental conditions of the Wuwei Oasis agricultural ecosystem in the middle reaches of the river basin and the Minqin Oasis agricultural ecosystem in the lower reaches. Under a same management level and investment of . material and energy, primary productiveness and economic benefits of the former are higher than those of the latter. Construction directions of Wuwei and Minqin oases should be different in order to alleviate the water- use contradiction between the middle and lower reaches. The construction objective of Wuwei Oasis should be efficient irrigated farming production system and Minqin Oasis should become a mixed forestry-pastoral-farming ecosystem taking ecological protection as its major function.

The Process of Cultivated Land and Water Resource Distribution Changing in Recent Decades in Upstream and Downstream in Shiyang Inland River Basin in Arid Area of Northwest China

Last century 50 - 70 years, the dam construction of Shiyang Inland River Basin (SIRB) profound impact on the distribution of water resources and arable land in the basin. Through data collection, field surveys and remote sensing image interpretation, we analysis the use of land and water resources change process in the middle and lower reaches of SIRB in recent decades. The results show: (1) The cultivated area of SIRB has been an upward trend in recent decades, The whole basin cultivated area has increased total 229,000 hm2 from 1973 to 2010 and mainly in the middle and lower reaches. Midstream increased by 149,700 hm2 accounting for 65.36 percent of total, downstream increased by 70,000 hm2 accounting for 30.70 percent of total. (2) The amount of surface water resources of downstream reduce significantly gradually since dam construction, and the water table sharp decline. While the volume of surface water resources come downstream from the 1950s accounted for 30 to 40 percent of the total gradually reduced to less than 10% in 2012;(3) since the arable land area of middle and lower reaches of SIRB basin substantial increase, so the surface water resource does not meet irrigation needs. Agricultural irrigation relies heavily on exploitation of groundwater to supplement, resulting in Regional Groundwater Depth dropped rapidly, and forming several huge funnel groundwater settlements. 20 years from 1981 to 2001 the groundwater level of midstream dropped from around 5m to around 10m in Wuwei, and in Minqin dam-region of downstream along faster rate of decline in 20 years fell from 8.52 m to 22.68 m. Dam construction project has changed the pattern of the basin water cycle, the middle reaches closure a large number of surface water resources led to downstream sharp decline. Downstream continued exploitation of groundwater formed a few huge funnel groundwater settlements, it caused serious ecological problems. The basin should adjust the industrial structure and develop water saving irrigation, promote a virtuous cycle of water resources, to achieve sustainable development, seek a sustainable development ways conversion natural oasis to artificial oasis efficiency in arid zone.

Population Distribution Evolution Characteristics and Shift Growth Analysis in Shiyang River Basin

In recent years, the population size and scale of the Shiyang River Basin unceasingly expanding lead to a series of ecological environment: surface water reducing, land desertification and Ground water levels fall, etc. Research evolution characteristics of population distribution and migration growth of Shiyang River Basin contribute to river water resources and the industrial development of the comprehensive management. The article using the distribution of population structure index, population distribution center of gravity model and the population migration growth analysis model analyzes the distribution of the population evolution characteristics and population migration growth characteristics of Shiyang River Basin in 2000 to 2010. The results show that: 1) Considering Shiyang River Basin, population density is generally low, population distribution difference is bigger and concentration distribution in the middle corridor plain and three big population distribution center of Minqin oasis area, presenting a “point-areas-ribbon” structure characteristics. 2) The population distribution trend of Shiyang River Basin is constantly concentration, but the change is slow;the population distribution of Minqin is in the highest concentration degree, but the trend has been declining. 3) The focus of population density in river basin locates in Liangzhou district of Daliu country;in ten years, it migrates about 1209 m to southwest Wuwei City direction, but migration along the direction things is bigger than the north and south direction. The focus of population density and the basin geometry center is far away. 4) For ten years, at the township for basic statistics unit, each level population migration change within the overall is not significant: township level > prefecture-level cities level > counties level. 5) For ten years, there are significant changes in population migration between watershed township units, Wuwei City and Gulang Town are the two main concentrations of population centers.

A study of benef its compensation mechanism for agricultural water rights trading under the restriction of ecological reconstruction:a case study of Shiyang River basin

Agricultural water allocation system based on priority rights has caused regional conflicts and downstream ecological degradation. It is the urgent need to introduce the concept of the initial water rights and establish benefits compensation mechanism to resolve such problems. This paper takes the Shiyang River basin as an example to calculate the opportunity cost of 0.97×10^8 m^3 of agricultural water encroached by the middle reach based on initial water right allocation system under which water is allocated in accordance with the ratio between agricultural population of two different regions concerning the downstream ecological reconstruction needs with Bio-economic model （BEM）. The results suggest that the total economic loss of Minqin County for ecological reconstruction amounts to 2.5 7×10^8 yuan, of which 1.68×10^8 yuan is ecological compensation, representing the economic loss Minqin suffered for ecological reconstruction which shouM burden beneficial groups of ecological reconstruction and 0.89 ×10^8 yuan is the economic loss Minqin suffered due to Liangzhou＇s encroachment behavior which should be compensated by Liangzhou.

石羊河流域气候变化及其对植被指数的影响

研究气候变化对植被覆盖的影响,对干旱区生态环境保护具有重要意义。以石羊河流域2000-2020年逐月气温、降水、日照、蒸发和NASA GIMMS归一化植被指数(NDVI)资料为基础,首先运用线性趋势法分析了气温、降水量、日照时数、蒸发量与NDVI的年、季节变化趋势,然后采用相关系数法研究了气候要素对NDVI的影响。结果表明:石羊河流域及各地年气温呈明显上升趋势,春、夏、秋季气温呈上升趋势,冬季(除民勤外)呈下降趋势;全流域及永昌、古浪、天祝年降水量呈增多趋势,民勤、凉州呈减少趋势,各季节降水量变化趋势不太一致;年日照时数除古浪呈增多趋势外,全流域及其他各地呈减少趋势,各季节日照时数变化趋势很不一致;年蒸发量除凉州呈减少趋势外,全流域及其他各地呈增多趋势,各季节蒸发量变化趋势也不太一致。石羊河流域及各地年NDVI呈显著增长趋势,除凉州春季外,各季节也呈增长趋势。年、季气温和降水量与NDVI基本呈正相关,气温、降水量对NDVI具有正贡献。年、季日照时数和蒸发量与NDVI相关性的正负差异较大,总体来看,日照时数对NDVI具有负贡献,蒸发量对NDVI具有正贡献。研究结果将为石羊河流域提高气候资源的利用率、调整种植结构和改善生态环境提供科学的参考依据。

协同调控水-农业-生态的干旱区多水源优化配置

干旱区农业发展往往以挤占生态用水和超采地下水为代价,考虑水-农业-生态互馈关系的水资源优化配置有助于平衡利益冲突。该研究以地下水均衡、经济效益和生态用水满足度为调控目标,构建基于水-农业-生态协同调控的多水源优化配置模型,并推求协调发展度计算式,提出了结合NSGA-Ⅱ算法和协调发展度的协同优化算法,分析石羊河流域水、农业和生态之间的权衡和协同关系,确定水-农业-生态协同提升下的水资源配置方案以及适宜的农业和生态用水比例。结果表明,现状条件下,六河子系统的水资源优化配置方案的经济效益可提升1.9%,实现地下水正均衡0.59亿m^(3);全流域农业和生态用水比例为90%∶10%,渠井用水比为67%∶33%。平水年保障蔡旗来水为3.48亿m^(3)/a时,能够以牺牲中游1.6%的经济效益实现生态用水满足度和地下水均衡量分别较基准情景提升4.8%和18.6%。研究为协同调控复杂的水-农业-生态关系提供了一种有效方法,可为干旱区流域水资源规划与管理提供参考。

石羊河流域生态系统碳储量时空变化及多情景模拟

以石羊河流域为例,利用InVEST模型评估1990~2020年土地利用变化带来的碳储量效应,耦合PLUS模型模拟2035年在自然发展、生态保护、水资源约束和经济发展情景下土地利用变化及其对碳储量的影响.结果表明:石羊河流域土地利用主要以未利用地,草地和耕地为主,占流域总面积的93%.1990~2020年石羊河流域耕地,水域和建设用地面积呈增长趋势,其余用地面积呈减少趋势.2020~2035年多情景模拟下,只有生态情境中林地和草地面积增加显著.1990~2020年流域碳储量整体呈增长趋势,其中以草地,未利用地和耕地碳储量贡献为主,占碳总量的86%.2020~2035年4种情景下的碳储量均有所增加,但生态保护情景中碳储量增加最为显著,共增加3.75×10^(6)t.自然发展情景和经济发展情景下,林地和草地转为耕地的面积远大于转入,碳储量损失较多.水资源约束情景下,耕地主要转出为草地和建设用地,其他各地类之间转换所承载的碳储量基本平衡.生态保护情景下,林地,草地等生态用地转入面积大于转出使区域碳储量增加.研究结果以期为石羊河流域提升陆地生态系统碳储量和规划未来国土空间提供科学依据.

基于生态系统恢复力的干旱区植被生态需水阈值计算方法与应用

本文以石羊河流域中下游为研究区,采用考虑生态系统恢复力(latitude of ecosystem resilience,LER)的月尺度生态需水评估方法计算19822020年植被月适宜生态需水量、最小生态需水量以及相应的生态缺水量,并与土壤水分特征值法(characteristic value of soil water,CVSW)进行比较,分析不同类型植被生长期的水分盈亏关系。结果表明:LER法和CVSW法计算结果相近,但LER法具有更大的生态需水阈值区间;天然降水基本可以满足植被的基本生存,但无法满足正常生长需求;LER法的适宜需水条件下,各植被生长期总体处于缺水状态,缺水严重程度排序为灌木林>其他林地>疏林地>高覆盖度草地>中覆盖度草地>有林地,全部植被生长期总适宜生态需水量为3.7×10^(8)m^(3),亏缺水量为1.2×10^(8)m^(3),同一植被亏缺水量基本符合春秋多、夏季少的规律;最小需水条件下,只有其他林地存在生长期缺水情况,全部植被生长期总最小生态需水量为0.8×10^(8)m^(3);在缺乏土壤水分数据的干旱地区,LER法具有良好的适用性。研究结果可为石羊河流域水资源高效利用和干旱区生态系统的恢复与重建提供理论参考。

考虑水转化过程的干旱区内陆河流域适宜灌溉规模

农业适水发展是保障干旱区水土资源高效利用和生态健康的关键,其核心在于如何科学确定灌溉规模,进而控制农业灌溉用水量。该研究以石羊河流域为研究区,在明确非灌溉需水量的基础上,基于水均衡模型计算考虑水转化过程的不同水文年农业灌溉可用水量,并构建多目标种植结构优化模型对作物种植结构进行调整,最后改进水热平衡模型构建考虑水转化过程的旱区适宜灌溉规模计算模型,分析流域不同情景下的适宜灌溉规模。结果表明:地表水地下水联合调控下,石羊河流域丰、平、枯水年的灌溉可用水量分别为18.97亿~21.57亿、14.75亿~17.51亿、12.31亿~14.95亿m^(3);优化作物种植结构后能够以减少2.94%的经济效益实现14.13%的灌溉节水;构建的适宜灌溉规模计算模型在干旱区内陆河流域具有较好的适用性,采用该方法得到现状条件下石羊河流域丰、平、枯水年的适宜灌溉规模分别为27.73万~31.66万、21.55万~25.76万、18.01万~22.03万hm^(2),提高节水水平、调整种植结构后,流域的适宜灌溉规模有所增加。现状2020年(平水年)的实际灌溉面积高于当地水资源能够承载的临界适宜灌溉规模,需压减2.13万~6.34万hm^(2)。研究结果可在宏观层面上为决策者制定适水农业发展方案提供理论依据。

晚中更新世以来武威盆地沉积特征——基于wv3钻孔的释光年代学研究

青藏高原东北缘河西走廊形成了一系列新生代盆地,是研究盆地沉积演化的重要区域。武威盆地位于河西走廊东部,盆地内沉积了较厚的新生代冲洪积地层。为了厘清武威盆地晚中更新世以来的沉积演化历史,笔者等在武威盆地石羊河中—上游处钻取了长207 m的wv3钻孔岩芯,获得了上部17 m岩芯的19个钾长石两步法pIR200 IR290年龄和2个多步法MET-pIRIR年龄,结合粒度资料,重建了武威盆地石羊河流域中—下游晚中更新世以来的光释光年代学框架和沉积历史。结果表明:两步法pIR200 IR290和多步法MET-pIRIR年龄在误差范围内一致。220~128 ka时期,沉积速率最小,为0.35 mm/ka,水动力条件较强,以侵蚀为主;128~108 ka(MIS 5d、MIS 5e)时期沉积速率为1.94 mm/ka,沉积物粒径由粗变细,表明此时水动力条件由强变弱;末次冰盛期到全新世早期(19~9 ka)沉积速率为2.78 mm/ka,沉积物粒径较细,表明此时水动力条件较弱,沉积速率最大,沉积为主。该地区新构造运动比较活跃,在末次间冰期至末次冰盛期期间存在逆冲活动。该研究对于揭示晚中更新世以来祁连山东北部石羊河流域沉积演化特征具有重要意义。