Water Consumption and Use Efficiency of Main Crops on Semi-drought Area of Western Liaoning Province

The laws of water consumption in corn,peanuts and millet on the semi-drought area of western Liaoning Province were studied through the FAO-Penman Monteith method and the water balance method.Among three corps,the amount of the day water demand,the whole growth period water demand and the soil water deficit of corn were all the largest.At the same time,its degree of agreement between the water demand and the level of precipitation was the worst,and its average in crop coefficient was larger.The amount of th...

Physical Effectiveness of Soil and Water Conservation Technologies in Drought Prone Areas of Western and Central Uganda

The effect of soil and water conservation （SWC） practices on controlling surface runoff and soil loss was studied in drought prone banana growing areas of Uganda, during the two major rainy seasons of 2014. The study was conducted at two sites-- Ntungamo （Southwest） and Sembabule （Central）, with comparable slopes of about 13%-25%. The treatments included mulch, manure, manure ＋ mulch and a control with no conservation. Results indicated that conservation practices of mulch and manure ＋ mulch significantly reduced surface runoff and soil loss by about 72%-85%, when compared to farmers＇ up-and-down cultivation practice （control）. It was also observed that significantly greater amounts of soil loss occurred from manure and control plots than the ones with mulch. Thus, the combination of manure and mulch is recommended for uptake by crop farmers in the study areas, if they are to overcome drought stress and adapt to changes in climate. More research is needed to quantify nutrient losses resulting from runoff under the different SWC techniques. Modeling such effects is essential in assessing the impacts of SWC practices on soil and crop productivity.

Using leaf area index(LAI) to assess vegetation response to drought in Yunnan province of China

Climatic extremes such as drought have becoming a severe climate-related problem in many regions all over the world that can induce anomalies in vegetation condition. Growth and CO2 uptake by plants are constrained to a large extent by drought.Therefore, it is important to understand the spatial and temporal responses of vegetation to drought across the various land cover types and different regions. Leaf area index(LAI) derived from Global Land Surface Satellite(GLASS) data was used to evaluate the response of vegetation to drought occurrence across Yunnan Province, China(2001-2010). The meteorological drought was assessed based on Standardized Precipitation Index(SPI)values. Pearson's correlation coefficients between LAI and SPI were examined across several timescales within six sub-regions of the Yunnan. Further, the drought-prone area was identified based on LAI anomaly values. Lag and cumulative effects of lack of precipitation on vegetation were evident, with significant correlations found using 3-, 6-, 9-and 12-month timescale. We found 9-month timescale has higher correlations compared to another timescale.Approximately 29.4% of Yunnan's area was classified as drought-prone area, based on the LAI anomaly values. Most of this drought-prone area was distributed in the mountainous region of Yunnan.From the research, it is evident that GLASS LAI can be effectively used as an indicator for assessing drought conditions and it provide valuable information for drought risk defense and preparedness.

Evaluation of Drought Hazard Area of GharehAghaj Basin in Iran, Using GIS

In GharehAghaj basin drought has the most profound effect on the way of living and regional economy. Drought Hazard by nature is a result of interrelated parameters concerned. The objective of this paper presents a model to assess hazard of drought using the Geographical Information System (GIS). The data analyzed have been gathered from the records, reports and maps published by the governmental offices of Iran. Various drought hazard indicators have different severity classification in different models. The drought hazard indicator maps take into account the meteorological, hydrological, physical and socioeconomic characteristics that related to drought hazard. Each of the hazard indicator maps and also final hazard map are classified into 4 hazard classes of drought: mild, moderate, severe and very severe. The final hazard classes were defined on the basis of hazard scores arrived at by assigning the appropriate attributes to the indicators and the final hazard map was prepared by overlaying different hazard indicator maps in the GIS, deploying the new model. The final Hazard Map shows that moderate hazard areas (89.87% of the basin) are much widespread than areas under severe hazard (10.13% of the basin) which are observed in the Southeast of the region.

Analysis of Drought Characteristics in the Inland Areas of Shandong Province from 1960 to 2013

Drought is one of the major meteorological disasters affecting the climate in China.In this paper,the interannual variation and seasonal distribution changes of drought at different time scales were analyzed with the standardized precipitation index( SPI) as the drought evaluation criterion to the precipitation data of the 5 meteorological stations of Jinan,Tai'an,Yiyuan,Shen County and Yanzhou from 1960 to 2013.The results showed that:(1) the frequency of drought was low in spring and summer in inland areas of Shandong Province,while autumn had frequent occurrences of moderate drought,and winter had frequent occurrences of heavy and severe droughts.(2) In the 1960 s,1980 s and early 21^(st) century,the number of droughts increased significantly,and the SPI values showed a significant decrease.(3) The 3-month time scale range was wide,during which the frequency of occurrence was high.The trend of SPI changes at the 12-month time scale was affected by the accumulation of antecedent precipitation,and the change was slow.The research results can provide a scientific reference for arid climate analysis and water resources management in agriculture and production in inland areas of Shandong Province.

A study on the temporal and spatial characteristics of droughts following earthquakes

According to the ＂jacking-up＂ theory, which relates the cause of earthquakes to outer core convection ascension bodies, the crust will gradually recover after an earthquake. In such cases, the crust is stretched, the underground temperature is reduced, precipitation decreases, and drought occurs. In this paper, precipitation is compared with ground temperature and seismic data to determine the spatial and temporal relationship between earthquakes and subsequent droughts. Our objective is to develop a new method of drought prediction. With a few exceptions in location, the analysis of the first drought to occur after the Ms 〉 7 earthquakes in China's Mainland and the adjacent areas since 1950 shows that droughts tended to occur in regions near earthquake epicenters and in the eastern regions of the epicenters at the same latitude within six months after the earthquakes. In addition, and the differences between the starting time of the earthquakes and the droughts nearly share the same probability of 0 to 6 months. After careful analysis of 34 Ms 〉 6.5 earthquakes occurring in western China from 1980 to 2011, we determined that a second drought tends to occur approximately six months following the first drought, indicating a quasi-half-year period. Moreover, the duration of the quasi-half-year fluctuation increases with the magnitude of earthquake, at approximately 2.5 years for Ms 6.5 earthquake and approximately 5 years for Ms 8 earthquake.

Spatial-temporal characteristics of drought detected from meteorological data with high resolution in Shaanxi Province, China

The spatial pattern of meteorological factors cannot be accurately simulated by using observations from meteorological stations(OMS) that are distributed sparsely in complex terrain. It is expected that the spatial-temporal characteristics of drought in regions with complex terrain can be better represented by meteorological data with the high spatial-temporal resolution and accuracy. In this study, Standard Precipitation Evapotranspiration Index(SPEI) calculated with meteorological factors extracted from ITPCAS(China Meteorological Forcing Dataset produced by the Institute of Tibetan Plateau Research, Chinese Academy of Sciences) was applied to identify the spatial-temporal characteristics of drought in Shaanxi Province of China, during the period of 1979–2016. Drought areas detected by SPEI calculated with data from ITPCAS(SPEI-ITPCAS) on the seasonal scale were validated by historical drought records from the Chinese Meteorological Disaster Canon-Shaanxi, and compared with drought areas detected by SPEI calculated with data from OMS(SPEI-OMS). Drought intensity, trend and temporal ranges for mutations of SPEI-ITPCAS were analyzed by using the cumulative drought intensity(CDI) index and the Mann-Kendall test. The results indicated that drought areas detected from SPEI-ITPCAS were closer to the historical drought records than those detected from SPEI-OMS. Severe and exceptional drought events with SPEI-ITPCAS lower than –1.0 occurred most frequently in summer, followed by spring. There was a general drying trend in spring and summer in Shaanxi Province and a significant wetting trend in autumn and winter in northern Shaanxi Province. On seasonal and annual scales, the regional and temporal ranges for mutations of SPEI-ITPCAS were different and most mutations occurred before the year 1990 in most regions of Shaanxi Province. The results reflect the response of different regions of Shaanxi Province to climate change, which will help to manage regional water resources.

Regional Evaluations of the Meteorological Drought Characteristics across the Pearl River Basin, China

Regional evaluation of drought characteristics provides critical information for water resource management. In this case, this study attempts to analyze the probability behaviors of drought events of a given severity in the Pearl River Basin and to construct severity-area-frequency curves of drought events. Due to possible impacts of complicated topographical properties and diverse climate types within the Pearl River Basin, the entire Pearl River Basin is subdivided into different homogeneous regions. In general, the Pearl River Basin can be categorized into four homogeneous regions, and the severity-area-frequency analysis results for the short-, medium- and long-term drought episodes within each homogeneous regions indicate stressful challenge for the water resource management in the Pearl River Basin due to the fact that severe droughts usually occur over the entire Pearl River Basin. Meanwhile, the Pearl River Delta will face a higher risk of drought when compared to other regions of the Pearl River Basin in terms of the medium-term drought. The Pearl River Basin is highly economically development and is heavily populated, thus impacts of droughts and related resilience resolutions or policies should be taken into account in the formulation of regional sustainable development of water resources and socio-economy within the Pearl River Basin, China.

Assessment of an Evapotranspiration Deficit Drought Index in Relation to Impacts on Ecosystems

Ecosystems have increasingly been subject to the challenge of heavy drought under global warming. To quantitatively evaluate the impacts of drought on ecosystems, it is necessary to develop a drought index that can sensitively depict the response of vegetation to drought evolution at a biological time scale. For the ability of direct connection between climate and ecosystem by deficit of evapotranspiration, in the present study, a drought index was defined based on standardized evapotranspiration deficit (SEDI), according to the difference between actual and potential evapotranspiration, to meet the need for highlighting drought impacts on ecological processes. Comparisons with traditional indices show that SEDI can reasonably detect droughts and climatic dry and wet transitions, especially at a monthly time scale, and can also regenerate long-term trends. Moreover, SEDI can more sensitively capture the biological changes of ecosystems in response to the dynamics of drought intensity, compared with the indices of precipitation and temperature. SEDI is more practical than the precipitation and temperature indices to highlight signals of biological effects in climate droughts. Hence, it has potential for use in assessments of climate change and its impact on ecosystems.

Detection of Spatial, Temporal and Trend of Meteorological Drought Using Standardized Precipitation Index (SPI) and Effective Drought Index (EDI) in the Upper Tana River Basin, Kenya

Drought events across the world are increasingly becoming a critical problem owing to its negative effects on water resources. There is need to understand on-site drought characteristics for the purpose of planning mitigation measures. In this paper, meteorological drought episodes on spatial, temporal and trend domains were detected using Standardized Precipitation Index (SPI) and Effective Drought Index (EDI) in the upper Tana River basin. 41 years (1980-2016) monthly precipitation data from eight meteorological stations were used in the study. The SPI and EDI were used for reconstruction of the drought events and used to characterize the spatial, temporal and trend distribution of drought occurrence. Drought frequency was estimated as the ratio of a defined severity to its total number of events. The change in drought events was detected using a non-parametric man-Kendall trend test. The main drought conditions detected by SPI and EDI are severe drought, moderate drought, near normal, moderate wet, very wet and extremely wet conditions. From the results the average drought frequency between 1970 and 2010 for the south-eastern and north-western areas ranged from 12.16 to 14.93 and 3.82 to 6.63 percent respectively. The Mann-Kendall trend test show that drought trend increased in the south-eastern parts of the basin at 90% and 95% significant levels. However, there was no significant trend that was detected in the North-western areas. This is an indication that the south-eastern parts are more drought-prone areas compared to the North-western areas of the upper Tana River basin. Both the SPI and the EDI were effective in detecting the on-set of drought, description of the temporal variability, severity and spatial extent across the basin. It is recommended that the findings be adopted for decision making for drought-early warning systems in the river basin.

Assessment of Agricultural Drought Risk in the Sichuan Basin Based on Information Diffusion Theory

Based on data of agricultural drought situation and sown area of main crops in each county or district of the Sichuan Basin, the spatial distribution and probability of agricultural drought risk at different risk levels were studied using normal information diffusion method, and the risk zoning was carried out. The results showed that normal information diffusion method could fit the distribution of agricultural drought risk in the Sichuan Basin. By comparison with the end of the 20^th century, agricultural drought risk in Meishan, Chongqing City and so on increased at the beginning of the 21^st century when x1≥ 10% or x1≥40%. Agricultural drought risk was low in the west of the Sichuan Basin, which was related to rich precipitation here, but it was high in Bazhong, Zhongjiang, Luxian and so forth. The risk zoning results can provide scientific references for disaster prevention and emergency management of government.

Persistence of four dominant psammophyte species in central Inner Mongolia of China under continual drought

Clarifying the persistence time of seedlings of dominant species under continual drought will help us understand responses of ecosystems to global climate change and improve revegetation efforts. Drought tolerance of four dominant psammophytic shrub species occurring in different environments was studied in the semi-arid areas of Inner Mongolian grasslands. Seedlings of Hedysarum laeve, Caragana korshinskii, Artemisia sphaerocephala and Artemisia ordosica were grown under four air temperature regimes （night/day： 12.5/22.5℃, 15/25℃, 17.5/27.5℃ and 20/30℃） within climate （air temperature and humidity） controlled, naturally lit glasshouses with a night/day relative humidity of 70%/50%. Pots were watered to field capacity for each temperature treatment. Soil water condition was monitored by weighting each pot every day using an electronic balance. Date of seedling death for each treatment was recorded and the dead plants were harvested. Plant dry weights were determined after oven drying at 80℃ for 3 days. Two Artemisia species had higher growth rates than H. laeve and C. korshinskii, and the growth of all four species increased with increasing temperatures. The two Artemisia species had the highest leaf biomass increment, followed by C. korshinskii, and then H. laeve. Shoot biomass increment was higher for A. ordosica and C. korshinskii, intermediate for A. sphaerocephala and lowest for H. laeve. C. korshinskii had the highest root biomass increment. The final soil water content at death for all four species varied from 1% to 2%. C. korshinskii, A. sphaerocephala, H. laeve and A. ordosica survived for 25-43, 24-41, 26-41 and 24-37 days without watering, respectively. C. korshinskii, A. sphaerocephala, H. Laeve, and A. ordosica seedlings survived longer at the lowest temperatures （12.5/22.5℃） than at the highest temperatures （20/30℃） by 18, 17, 15 and 13 days, respectively. Increased climatic temperatures induce the death of seedlings in years with long intervals between rainfall events. The adaptation of seedlings to droughts should be emphasized in revegetation efforts in the Ordos Plateau, Inner Mongolia.

Regional Drought Severity Assessment at a Basin Scale in the Limpopo Drainage System

A spatial analysis of drought characteristics in the Limpopo basin is undertaken to evaluate its regional implications to water management challenges. In this study, drought duration, frequency and severity are investigated. In addition drought Severity-Area-Frequency (SAF) curves were constructed. The entire Limpopo River Basin is subdivided into four homogeneous regions based on topographic and climate variations in the basin, which was constructed with the K-Means Clustering algorithm. Using the medium range time series of the Standardized Precipitation Index (SPI) as an indicator of drought for each homogeneous region, monthly and annual SAF curves and maps of probability of drought occurrence were produced. The results indicated localized severe droughts in higher frequencies compared to moderate to severe low frequency droughts spread over wider areas in the basin. The approach can be used to develop improved drought indicators to assess the relationship between drought hazard and vulnerability and to enhance the performance of methods currently used for drought forecasting. In general, this preliminary investigation reveals that the western part of the basin will face a higher risk of drought when compared to other regions of the Limpopo Basin in terms of the medium-term drought patterns. The Limpopo Basin is water stressed and livelihood challenges remain high, thus impacts of droughts and related resilience options should be taken into account in the formulation of regional sustainable water resources development strategies.

Interactive Effects of Drought Stress and Phytohormones or Polyamines on Growth and Yield of Two M(<i>Zea maize</i>L) Genotypes

Two maize genotypes (Nefertiti and Bashaier) were picked up from nine maize genotypes during the early vegetative growth (25 days) to be cultivated in open field upon the crop yield under the different drought stress levels (90,70,50,30) or under the interaction effect of drought stress and phytohormones or polyamines. According to the data of growth criteria, the maize genotype Nefertiti was found to be the most drought sensitive genotype, while the genotype Bashaier was found to be the most drought resistant genotype. Additionally while the photosynthetic pigments remained more or less unchanged in genotype Bashaier, their biosynthesis destroyed earlier in the drought sensitive genotype (Nefertiti). Also while the genotype Bashaier absorbed and accumulated a sufficient amount of mono and divalent cations (K+, Ca++ and Mg++), the genotype Nefertiti did not. Accordingly while the genotype Bashaier gave a crop yield up to 50% field capacity, the genotype Nefertiti gave a crop yield only up to 70% field capacity and failed to give a crop yield beyond this level. The interaction effect of drought stress and phytohormones and polyamines improved the all above characteristics. Interestingly each of these activators considerably improved the production of crop yield only in genotype Bashaier specially polyamines they produced more than 60% field capacity and at the level of 30% field capacity (the level which did not give crop yield in this genotype). However, phytohormones in generally did not make an important effect on the crop yield in genotype Nefertiti although they improved the dry matter production during the vegetative stages. Such situation seemed to be complicated and borne many questions to be studied in the future.

Analysis on the Reasons for Consecutive Severe Droughts in Autumn and Winter in Xuzhou in 2008

[Objective] The aim was to study the reasons for consecutive severe droughts in autumn and winter. [Method] By dint of precipitation in the observatory station and NCEP/NCAR reanalysis data in observatory station, the circulation background, vertical movement, abnormal temperature and changes of water vapor conditions in Xuzhou from October 2008 to January 2009 were expounded to reveal the causes for consecutive drought in autumn and winter. [Result] Xuzhou was under stable situation for a long time in autumn and winter in 2008, being behind east coastal trough, the downward airstream prevailing; the south trough intensity was weak, and in addition to the east subtropical high and weak intensity, the water vapor transportation condition in Indian Ocean and South Sea was unfavorable. The autumn was warm and the cold air was weak; ever since winter, there were several cold air activities. But the influencing body was in the east, and the south warm and wet airstream was insufficient. Thus, they couldn’t met, which resulted into gale and lower temperature and less precipitation when under the influence of cold air. [Conclusion] The study provided theoretical basis for the prevention of drought in the area.

基于水库旱限水位的大型灌区水资源空间均衡优化调控

由于自然地理特征和经济社会活动的差异,大型灌区水资源分布和利用在时空上是不平衡的,尤其是受水文气象波动影响的农业灌溉供水,需要借助水利工程进行水资源空间均衡调控。目前按典型水平年制订的常规调配水方案无法展现水资源空间均衡状态在年内的变化响应过程,也无法考虑水资源在年际间调配的需求。鉴此,本文基于灌区水资源系统空间均衡评价模型和半分布式水资源系统模拟模型,以干旱年缺水时段平均水资源系统空间均衡度最大为目标,以骨干水库分期分级旱限水位和灌区分单元分用水户限供比例为调控变量,运用遗传算法开展大型灌区水资源系统空间均衡优化调控研究。淠河灌区应用结果显示:骨干水库的分级分期旱限水位能够实现水资源在年内和年际时间上的均衡调节,而分单元分用水户的限制供水措施能够使水资源在空间上得到合理配置。二者共同作用能更好地协调灌区供需水在时程分布和空间均衡间的关系,相较于运行现状能大幅提升水资源系统空间均衡度,增强灌区的可持续发展能力,为基于旱限水位的复杂水资源系统管理和应用提供新的思路。

不同气象干旱指数在北疆绿洲农业区适用性分析

选取北疆绿洲农业区11个气象站1961—2020年的数据,按月尺度计算降水距平百分率(PA)、标准化降水指数(SPI)、标准化降水蒸散指数(SPEI)、K指数和气象干旱综合指数(MCI)5种干旱指数,通过比较这些指数的相关性、不同等级的干旱发生频率以及在典型干旱年份的识别能力,分析各指数在该区域的适用性。结果表明,PA和SPI对降水亏缺有敏感的反应,但对温度的关联较弱,未充分考虑增温对干旱的影响;MCI与温度和降水的关联均较弱,倾向于低估重旱和特旱;SPEI和K指数与温度和降水均有较好的关联,但K指数过多地报告中度至重度干旱,而SPEI则全面考虑了温度和降水对干旱的综合影响,其结果更符合实际情况。由于SPEI计算蒸散发采用的Thornthwaite方法可能高估了温度对干旱的影响,在降水显著偏少、温度偏差较小的情况下,SPI的监测结果可能比SPEI更为严重,因此,建议结合SPI使用,以弥补这一不足。

基于SPEI指数的淮北地区气象干旱时空特征研究

【目的】研究淮北地区1961—2022年气象干旱时空特征。【方法】采用淮北地区21个站点1961—2022年实测气象资料,计算月、季、年尺度各站点及区域平均标准化降水蒸散指数(SPEI),分析该区干旱发生频次、干旱趋势及干旱发生强度时空变化特征。【结果】(1)1961—2022年淮北地区月、季、年尺度SPEI呈下降趋势。(2)月尺度干旱场次及干旱平均持续时间呈逐年上升趋势,淮北站年均干旱场次最多(0.73次/年),泗县站干旱平均持续时间最长(4.61月/次),淮北站月尺度干旱风险最高。(3)春季、秋季呈不显著干旱化趋势,夏季、冬季呈不显著湿润化趋势;冬季干旱频率和干旱发生强度最高,分别为34.43%、21.86%;夏季局域性及其以上干旱频率最高;冬季全域性及其以上干旱频率最高;中东部及西南部春季干旱频率较高,东南部夏季干旱频率较低,东部和北部秋季干旱频率较高,西部和东北部、东南部边缘地区冬季干旱频率较高。(4)年尺度淮北地区呈不显著干旱化趋势(-0.01/10 a),干旱站次比逐年增加(1.4%/10 a);北部干旱化倾向较高,西部及东南部干旱发生强度较高,东北部及西南部干旱频率较高。【结论】淮北地区整体呈干旱化趋势,区域间干旱频率、干旱发生强度差异明显。

雨养农业区冬小麦品种灌浆期抗旱耐逆性评价技术规程

为进一步推进抗旱耐逆小麦品种的快速筛选及其推广应用,提高耐旱育种效率,通过半干旱雨养农业区田间生产条件下灌浆期小麦气孔性状多年多点的测定,明确小麦灌浆期抗旱耐逆性判定规则,联合主成分分析和隶属函数值方法,从适用范围、规范性引用文件、术语和定义、技术原理、基本要求、田间管理、气孔性状调查分析、评价指标的计算及评价等级等方面总结出雨养农业区冬小麦品种灌浆期抗旱耐逆性综合评价技术规程。

基于温度植被干旱指数的关中地区旱情监测

及时准确地进行区域尺度的干旱监测对于保障农业生产和保护粮食安全具有重要指导意义。该研究基于2001—2020年的MOD11A2地表温度8 d合成产品与MOD13A1植被指数16 d合成产品,通过地表温度(land surface temperature,LST)和归一化植被指数(normalized difference vegetation index,NDVI)数据构建NDVI-LST特征空间,获取关中地区2001—2020年20 a时间序列的温度植被干旱指数(temperature vegetation dryness index,TVDI),分析关中地区干旱时空分布演变特征和干旱影响成因,探索其未来演变趋势。结果表明:1)关中地区近20 a来TVDI平均值为0.57,干旱类型整体上属于正常的干旱状态,82.00%的地区干旱变化状况为稳定不变,渭河冲积平原干旱程度较为严重,其次是渭北旱塬地区,南部秦岭地区较为湿润;2)关中地区未来干旱情况有所缓解,7.71%的研究区将持续变湿,36.24%的地区由干变湿;3)关中地区的TVDI值与海拔、坡度、降水量呈现负相关,与气温呈现正相关关系,林地、草地覆盖对缓解干旱具有积极意义。温度植被干旱指数从区域尺度上实现了干旱状况的定量化表征,在关中地区具有较好的适用性,遥感干旱监测结果可为关中地区抗旱对策的制定提供理论基础和科学依据。