Prediction of Maize Yield and Its Component Factors in Yellow River Irrigation Area of Ningxia under Climate Change

[Objective] The aim was to quantitatively predict the variation trend of maize yield in Yellow River irrigation area of Ningxia under future climate change scenarios.[Method] Based on the data of daily temperature,precipitation and radiation in 25 km × 25 km grid in Ningxia from 2010 to 2100 obtained by regional climate model,maize yield in Yellow River irrigation area of Ningxia in the 21st century was studied by means of corrected CERES-Maize model.[Result] With climate warming,maize yield in Yellow River irrigation area of Ningxia in 2020s and 2050s showed increase trend compared with base years（average in 1961-1990）when current adaptive maize variety and optimum production management measures were adopted,while maize yield went down in 2080s with the further increase of temperature.The grain number per spike and spike grain weight as the yield components of maize also showed the same trend with maize yield.In 2020s and 2050s,the increase of maize yield under B2 scenario was higher than that under A2 scenario,while the decrease of maize yield under B2 scenario was lower than that under A2 scenario in 2080s.[Conclusion] With the increase of temperature,maize yield in Yellow River irrigation area of Ningxia went up firstly and then went down.

Dataset of Comparative Observations for Land Surface Processes over the Semi-Arid Alpine Grassland against Alpine Lakes in the Source Region of the Yellow River

Thousands of lakes on the Tibetan Plateau(TP) play a critical role in the regional water cycle, weather, and climate. In recent years, the areas of TP lakes underwent drastic changes and have become a research hotspot. However, the characteristics of the lake-atmosphere interaction over the high-altitude lakes are still unclear, which inhibits model development and the accurate simulation of lake climate effects. The source region of the Yellow River(SRYR) has the largest outflow lake and freshwater lake on the TP and is one of the most densely distributed lakes on the TP. Since 2011,three observation sites have been set up in the Ngoring Lake basin in the SRYR to monitor the lake-atmosphere interaction and the differences among water-heat exchanges over the land and lake surfaces. This study presents an eight-year(2012–19), half-hourly, observation-based dataset related to lake–atmosphere interactions composed of three sites. The three sites represent the lake surface, the lakeside, and the land. The observations contain the basic meteorological elements,surface radiation, eddy covariance system, soil temperature, and moisture(for land). Information related to the sites and instruments, the continuity and completeness of data, and the differences among the observational results at different sites are described in this study. These data have been used in the previous study to reveal a few energy and water exchange characteristics of TP lakes and to validate and improve the lake and land surface model. The dataset is available at National Cryosphere Desert Data Center and Science Data Bank.

Estimation of water balance in the source region of the Yellow River based on GRACE satellite data

Water storage has important significance for understanding water cycles of global and local domains and for monitoring climate and environmental changes. As a key variable in hydrology, water storage change represents the sum of precipitation, evaporation, surface runoff, soil water and groundwater exchanges. Water storage change data during the period of 2003-2008 for the source region of the Yellow River were collected from Gravity Recovery and Climate Experiment （GRACE） satellite data. The monthly actual evaporation was estimated according to the water balance equation. The simulated actual evaporation was significantly consistent and correlative with not only the observed pan （20 cm） data, but also the simulated results of the version 2 of Simple Biosphere model. The average annual evaporation of the Tangnaihai Basin was 506.4 mm, where evaporation in spring, summer, autumn and winter was 130.9 mm, 275.2 mm, 74.3 mm and 26.1 mm, and accounted for 25.8%, 54.3%, 14.7% and 5.2% of the average annual evaporation, respectively, The precipitation increased slightly and the actual evaporation showed an obvious decrease. The water storage change of the source region of the Yellow River displayed an increase of 0.51 mm per month from 2003 to 2008, which indicated that the storage capacity has significantly increased, probably caused by the degradation of permafrost and the increase of the thickness of active layers. The decline of actual evaporation and the increase of water storage capacity resulted in the increase of river runoff.

Analysis of Water Resources Supply and Demand and Security of Water Resources Development in Irrigation Regions of the Middle Reaches of the Heihe River Basin, Northwest China

Based on the data for meteorology, hydrology, soil, planting, vegetation, and socio-economic development of the irrigation region in the middle reaches of the Heihe River basin, Northwest China, the model of balance of water supply and demand in the region was established, and the security of water resource was assessed, from which the results that the effects of unified management of water resources in the Heihe River basin between Gansu Province and Inner Mongolia on regional hydrology are significant with a decrease in water supply diverted from Heihe River and an increase in groundwater extracted. In addition, it was found that the groundwater level has been steadily decreasing due to over pumping and decrease in recharges. In present year （2003）, the volume of potential groundwater in the irrigation districts is far small because of the groundwater overdraft; even in the particular regions, there is no availability of groundwater resources for use. By 2003, water supply is not sufficient to meet the water demand in the different irrigation districts, the sustainable development and utilization of water resources are not secured, and the water supply crisis occurs in Pingchuan irrigation district. Achieving water security for the sustainable development of society, agriculture, economy, industry, and livelihoods while maintaining or improving the abilities of the management and planning of water resources, determining of the reasonable percentage between water supply and groundwater utilization and water saving in agricultural irrigation are taken into account. If this does not occur, it is feared that the present performance of water development and planning may further aggravate the problem of scarcities of water resources and further damage the fragile ecological system.

Influencing factors of water resources in the source region of the Yellow River

Taking the source region of the Yellow River as a study area and based on the data from Madoi Meteorological Station and Huangheyan Hydrological Station covering the period 1955-2005, this paper analyses the changing trends of surface water resources, climate and frozen ground and reveals their causes. Results show that there exist frequent fluctuations from high to low water flow in the 51-year period. In general, the discharge has shown a de- clining trend in the 51 years especially since the 1990s. The annual distribution shows one peak which, year on year is getting smaller. （1） Precipitation has a significant and sustained influence on discharge. （2） A sharp rise of temperature resulted in the increase of evaporation and the decrease of discharge, which has a greater effect than on ice-snow melting. （3） Frozen ground tends to be degraded markedly. There is a significant positive correlation be- tween the permafrost thickness and the discharge. （4） Evaporation rates are significantly increasing, leading to the decrease of discharge. 70% of the discharge reduction resulted from climate change, and the remaining 30% may have been caused by human activities.

THE RATIONAL UTILIZATION OF WATER RESOURCES IN IRRIGATED AREA OF THE YELLOW RIVER IN NINGXIA

The paper describes the water resources in the irrigated area of Ningxia, China, andthe methods for improving the utilization of the water resources, and puts forward somesuggestions so as to utilize the water resources rationally. The history of irrigation farming in Ningxia can be traced back to more than two thou-

Analysis of water vapour flux between alpine wetlands underlying surface and atmosphere in the source region of the Yellow River

An underlying wetland surface comprises soil, water and vegetation and is sensitive to local climate change. Analysis of the degree of coupling between wetlands and the atmosphere and a quantitative assessment of how environmental factors influence latent heat flux have considerable scientific significance. Using data from observational tests of the Maduo Observatory of Climate and Environment of the Northwest Institute of Eco-Environment and Resource, CAS, from June 1 to August 31, 2014, this study analysed the time-varying characteristics and causes of the degree of coupling(Ω factor)between alpine wetlands underlying surface and the atmosphere and quantitatively calculated the influences of different environmental factors(solar radiation and vapour pressure deficit) on latent heat flux. The results were as follows:(1) Due to diurnal variations of solar radiation and wind speed, a trend developed where diurnal variations of the Ω factor were small in the morning and large in the evening. Due to the vegetation growing cycle, seasonal variations of the Ω factor present a reverse "U" trend. These trends are similar to the diurnal and seasonal variations of the absolute control exercised by solar radiation over latent heat flux. This conforms to the Omega Theory.(2) The values for average absolute atmospheric factor(surface factor or total) control exercised by solar radiation and water vapour pressure are 0.20(0.02 or 0.22) and 0.005(-0.07 or-0.06) W/(m2·Pa), respectively. Generally speaking, solar radiation and water vapour pressure deficit exert opposite forces on latent heat flux.(3) At the underlying alpine wetland surface, solar radiation primarily influences latent heat flux through its direct effects(atmospheric factor controls). Water vapour pressure deficit primarily influences latent heat flux through its indirect effects(surface factor controls) on changing the surface resistance.(4) The average Ω factor in the underlying alpine wetland surface is high during the vegetation growing season, with a value of 0.38, and the degree of coupling between alpine wetland surface and atmosphere system is low. The actual measurements agree with the Omega Theory. The latent heat flux is mainly influenced by solar radiation.

Effects of muddy water irrigation with different sediment gradations on nitrogen transformation in agricultural soil of Yellow River Basin

Muddy water irrigation has been widely practiced in the Yellow River Basin for agricultural production and is an important method of economical and intensive utilization of water resources.In this study,the effects of sediment gradation,sand content,and soil moisture content on nitrogen(N)transformation were studied through a series of experimental tests.The results indicated that muddy water irrigation significantly affected agricultural soil physical and biological properties as well as N transformation.Soil bulk density,total porosity,pH,and microbial enzyme activities significantly correlated with N transformation as affected by the interaction between sediment and soil moisture.Sediment addition generally increased the soil bulk density and reduced the soil porosity and pH significantly,and the optimum moisture for promotion of the N transformation rate was 80%of the water-filled pore space.Therefore,muddy water irrigation has a potentially long-term influence on agricultural N cycles in semi-arid regions of northwestern China.This could provide a theoretical basis for scientific and rational use of muddy water for irrigation.

Methodology to determine regional water demand for instream flow and its application in the Yellow River Basin

In order to realistically reflect the difference between regional water demand for instream flow and river ecological water demand as well as to resolve the problem that water demand may be counted repeatedly, a concept of regional water demand for minimum instream flow have been developed. The concept was used in the process of determining river functions and calculating ecological water demand for a river. The Yellow River watershed was used to validate the calculation methodology for regional water demand. CaIculation results indicate that there are significant differences in water demands among the different regions. The regional water demand at the downstream of the Yellow River is the largest about 14.893 × 10^9 m^3/a. The regional water demand of upstream, Lanzhou-Hekou section is the smallest about -5.012 × 10^9 m^3/a. The total ecological water demand of the Yellow River Basin is 23.06 × 10^9 m^3/a, about the 39% of surface water resources of the water resources should not exceed 61% in the Yellow River Basin. Yellow River Basin. That means the maximum available surface The regional river ecological water demands at the Lower Section of the Yellow River and Longyangxia-Lanzhou Section exceed the surface water resources produced in its region and need to be supplemented from other regions through the water rational planning of watershed water resources. These results provides technical basis for rational plan of water resources of the Yellow River Basin.

Water Environmental Degradation of the Source Area of the Yellow River on Northeast Qinghai-Tibet Plateau

The issue on water environmental degradation in the source area of the Yellow River has been one of very serious ecological and socially economic problems. The temporal-spatial changes of water environment led to the decreasing of land capacity and river disconnecting. The status of water environmental degradation in this paper was analyzed based on the data and field investigation. The results indicated that the surface water area in the region has obviously decreased owing to the climate changes and human irrational use of water resources and the continuous lowering of the regional groundwater table and the steadily decreasing tendency of the flow rate in the source areas of the Yellow River.

A STUDY ON THE WATER RESOURCES AND SEDIMENT PROBLEMS IN THE IRRIGATED AREA OF NORTHWEST SHANDONG PROVINCE

There are very serious water and sediment problems in the irrigated areas of northwest Shandong Province. In upper reaches of the irrigated area, the Yellow River water are widely used for farmland watering while leaving the ground water unusedion. But in the lower reaches, there is not enough surface water to be channeled for irrigation, so the ground water has always been over extracted, in some parts of the lower reaches, the descending water table caused the formation of funnel. Siltation in canals are very difficult to be cleared up, the drop of agriculture yield in the sandy land close to the channel head and along the main channels impair the living conditions of the local people. The conflicts between the excessive dependence on the Yellow River and the decreasing tendancy of water amount provided by the Yellow Ricer forces the local government to find new ways to solve the water resource problems. The answer could be: Using new technique for the irrigated system, pay more attention to the ground water development, and the construction and maintenance of wells.

黄河流域水资源-生态-城市-产业协同演进研究

为考察黄河流域水资源-生态-城市-产业协同的动态演进及其地区差异和来源,基于2016—2020年黄河流域76个主要地级市数据,采用协同度模型、核密度估计和Dagum基尼系数及其分解方法进行实证测度。结果表明:处于初级、中级和良好协同的城市数量分别为30个、33个和13个。各城市协同度水平呈现上升趋势,但城市间绝对差异在扩大,相对差异在缩小;除呼包鄂榆城市群外,其他六大城市群协同度绝对差异均呈扩大趋势。黄河上游和下游内部差异呈下降趋势,中游内部差异呈上升趋势;上游和中游间差异最大,且呈现进一步扩大趋势,上游和下游间差异逐渐缩小。呼包鄂榆城市群群内差异最小,关中城市群群内差异最大;关中城市群与山东半岛城市群群间差异最小,晋中城市群与山东半岛城市群群间差异最大。未来应进一步加强要素协同、区域协同,发挥各地区动态比较优势,因地制宜推进黄河流域生态保护和高质量发展重大国家战略深入实施。

宁夏引黄灌区果园生草处理对土壤理化性质的影响

本研究选用多年生黑麦草、紫花苜蓿、高羊茅、长柔毛野豌豆4种功能草种,以清耕和自然生草作为对照,探究不同生草处理对果园土壤理化性质的影响。结果表明,与多年生黑麦草生草处理相比,紫花苜蓿与长柔毛野豌豆生草处理可以显著提高0~20 cm土层土壤总孔隙度和0~20 cm、21~40 cm土层田间持水量(P<0.05),显著降低0~20 cm土层土壤容重(P<0.05)。与处理前相比,2022年10月紫花苜蓿与长柔毛野豌豆生草处理的土壤有机质含量、全盐含量、碱解氮含量(0~20 cm土层)、有效钾含量(0~20 cm土层)显著提高(P<0.05),土壤pH(0~20 cm土层)显著降低(P<0.05)。因此,在干旱和半干旱地区可以选择苜蓿和长柔毛野豌豆进行果园生草处理。本研究结果为改良果园土壤,提高水果产量提供了理论依据。

考虑生态耗水的干旱区绿洲灌溉用水效率评价指标与方法

针对现行干旱区绿洲尺度灌溉用水效率评价对生态服务效益考虑不足的问题,提出了在绿洲尺度上考虑生态耗水的灌溉用水效率评价指标和方法,并应用于宁夏引黄灌溉绿洲。结果表明:宁夏引黄灌溉绿洲农田蒸散消耗水量中的灌溉水量平均占比达74.7%,生态系统蒸散消耗水量中的灌溉水量平均占比达39.8%,灌溉水对生态系统的支撑作用显著;考虑生态耗水前后的灌溉用水效率差为0.052~0.074,占未考虑生态耗水灌溉用水效率的13.9%~16.1%,灌溉水的生态服务效益明显;提出的评价指标与方法合理可行,能客观反映干旱区灌溉用水的综合效益。

基于时序Sentinel-2影像的引黄灌区作物结构提取和供需水分析

在黄河流域用水指标严格控制的背景下,以山东省东营市垦利区引黄灌区为例,利用2022年时序Sentinel-2遥感影像构建作物生育期的NDVI时间序列,采用决策树分类方法提取灌区作物种植结构,基于垦利站气象资料和Penman-Monteith公式,分析了1973—2022年各作物的需水特性,利用遥感影像解译的各作物种植面积,计算了2022年灌区作物在不同降水保证率(5%、25%、50%、75%、95%)条件下的灌溉总需水量,结合2023年分配给灌区作物的灌溉水指标探究了灌溉水资源供需之间的平衡。结果表明:基于NDVI时间序列构建决策树分类方法可有效提取作物的种植结构,总体分类精度为85.07%,Kappa系数为0.819,能够满足作物灌溉需水量的研究。作物净灌溉需水量年际波动较大,水稻和冬小麦补充灌溉水量在所有作物中位列前两位,均值分别为913 mm和410 mm;处于雨季生长的夏玉米、夏大豆补充灌溉水量较小且灌溉需求均值较小。研究区2023年分配的灌溉水指标在降水保证率为50%时研究区灌溉水亏缺量为235.5万m^(3),在降水保证率为75%和95%时灌溉水亏缺量分别为1 754.5万m^(3)和2 261.5万m^(3)。

基于CNN-OBIA的黄河源区水体提取及时空变化

准确识别水体信息是分析地表水时空动态变化的重要技术手段。针对目前各种长时序水体信息提取方法精度低的问题,基于Landsat遥感影像,选用1986~2022年5484景黄河源区遥感影像,分别运用卷积神经网络结合面向对象(CNN-OBIA)和多指数水体检测规则(MIWDR)两种方法提取了黄河源区的地表水体,并对两种方法的提取精度进行了对比分析。在此基础上,探究了1986~2022年黄河源区水体信息的时空变化特征,并对其主要气候因素进行相关分析。结果表明:①CNN-OBIA的总体精度和Kappa系数分别为96.78%和0.93,MIWDR的总体精度和Kappa系数分别为94.28%和0.88,总体而言,CNN-OBIA的提取精度高于MIWDR方法。CNN-OBIA的提取结果可以很好地保持水体边界完整性和有效去除山体阴影,可以较好地对细小河流进行提取。②研究区水体总面积呈现出先减少(1986~2001年)后增加(2001~2022年)的变化趋势。③相关性分析表明,降水和气温与水体面积的变化均表现出显著正相关。

Study on the changes of water cycle and its impacts in the source region of the Yellow River

The water cycle in the source region of the Yellow River underwent great changes in the 1990s. The major features of the changes are as follows: the gauged runoff declined significantly while the precipitation increased slightly, and the runoff process was more concentrated on the flood season. Water balance analyses indicate that the pondage was kept in the status of negative equilibrium, causing eco-environmental problems. The runoff decrement is due to evaporation increment in this region. Studies show that the runoff process in this region is closely related to that of the other hydrological stations in the upper reaches. When the runoff declines in the source regions, the amount of water also declines in the whole upper reaches of the Yellow River, affecting the balance between water demand and supply. Meanwhile changes will take place in the water cycle of the river course system when the eco-environment deteriorates. The trend of water cycle change in the source region is that the runoff will keep declining with the increment of evaporation caused by temperature rise in the northwest of China in the 21st century. But the hydraulic engineering in the source region will help to mitigate the deterioration of local eco-environment system, though the impacts to the lower reaches of this project may not be the case.

Response of water budget to recent climatic changes in the source region of the Yellow River

Discharge in the source region of the Yellow River significantly declined after 1990.China Meteorological Administration(CMA) data show that precipitation in this region was low in the 1990s but returned to above normal after 2002;in recent decades there has been rapid warming of surface air,moistening and wind speed decrease.To investigate the influences of recent climatic changes on the water budget,this study simulates the surface water budget at CMA stations within and surrounding the source region during 1960-2006,using an improved land surface model.Results indicate that the spatial pattern of precipitation change is an important factor(except for precipitation amount and intensity) in determining the response of runoff to precipitation changes.Low runoff in the 1990s was consistent with precipitation amount and intensity.The recovery of precipitation after 2002 is mainly from increased precipitation in the dry area of the source region.Evaporation was mainly limited by water availability in this dry area,and thus most of the precipitation increase was evaporated.By contrast,energy availability was a more important influence on evaporation in the wet area.There was more evaporation in the wet area because of rapid warming,although precipitation amount partly decreased and partly increased,contributing to the reduction of runoff after 2002.This control on evaporation and its response,together with the modified spatial pattern of precipitation,produced a water budget unfavorable for runoff generation in the source region during recent years.

黄河流域水稀缺风险评价

基于黄河流域水稀缺特点及其成因,提出了综合考虑水量､水质和生态需水因素的流域水稀缺风险(WSR)评估框架,以此评估了2017年黄河流域90个地级市42个部门的直接水稀缺风险损失(DWSR),并通过构建城市尺度环境拓展多区域投入产出模型(MRIO),评估了城市间贸易驱动的间接水稀缺风险损失(IWSR).结果表明:流域DWSR和IWSR分别约为28941.49亿元和34464.08亿元,贸易导致的间接经济损失大于直接经济损失;各城市DWSR和IWSR整体上呈现一定的空间差异性,但高风险城市具有明显的空间集聚性和重合性,主要集中在流域中下游的山东､河南两省,如潍坊､淄博､郑州等;IWSR转移主要由各省内的城市间贸易产生,省际间的风险转移没有形成明显的热点区域;农林牧渔业､化学工业､石油加工､炼焦和核燃料加工业等部门的DWSR较高,同时也是主要的IWSR出口部门.建议结合识别出的重点城市､关键部门等全面加强WSR管理,协同推进黄河流域节水控水､水质改善和生态用水保障,促进流域水资源节约集约高效利用.

黄河九省(区)水资源绿色效率时空格局与影响因素研究

为探索黄河九省(区)水资源绿色效率,采用SBM-DEA模型和Tobit模型对黄河九省(区)99个地级市水资源绿色效率的时空分布及影响因素进行分析。研究结果表明:1)黄河九省(区)水资源绿色效率整体呈上升趋势,下游的中原城市群和山东半岛城市群水资源绿色效率较高,上游的兰西城市群和宁夏沿黄城市群相对较低;2)黄河九省(区)水资源绿色效率空间集聚分布显著,“高-高”型城市主要集聚在下游经济较发达的省份,水资源绿色效率呈显著的正向空间自相关,并存在集聚现象和溢出效应;3)第一产业和第三产业规模、水资源禀赋和节水水平对水资源绿色效率提升具有显著积极影响,外商直接投资对水资源绿色效率的影响较为消极。