河套平原次生盐渍化地区地下水动态调控模拟研究

在盐荒地野外水盐运移试验的基础上,建立了基于饱和-非饱和带的土壤水盐运移模型,以地下水埋深为调控关键因子,利用HYDRUS软件模拟了河套灌区荒地不同时段的不同控制地下水埋深条件下包气带水盐变化规律。通过模型反算,定量确定了不同时段防治盐渍化的地下水埋深临界值。模拟结果:在年内2~3次灌溉淋滤的条件下,3月-6月份(春融返盐期)控制地下水埋深大于2.4~2.7 m,7月初-9月初,控制地下水埋深大于1.8~2.1 m,9月中旬-11月中旬(秋浇积盐期),控制地下水埋深大于1.5~1.8 m,11月下旬-3月上旬(冬封期)控制地下水埋深大于2.0~2.3 m可使0~50 cm土层的全盐量基本小于0.2%,处于非盐渍化状态。研究结果可为河套平原次生盐渍化区水盐运移调控和盐渍化改良提供借鉴和依据,具有重要理论和应用意义。     

基于ArcGIS的河套灌区土壤盐碱化空间分析

以河套灌区内沙壕渠灌域为代表,采用ArcGIS 9.2软件,对土壤采样点不同深度土层的盐化和碱化指标进行等级划分,并进行空间插值,得到了不同深度的盐化分布专题图和碱性分布专题图,实现了盐化、碱化分布的空间可视化。插值结果表明:在空间分布上盐化分布比碱化分布具有更强的变异性,两者在0～10、10～20 cm和20～50 cm土层上具有相同的分布规律,随着土壤深度的增加盐碱化程度呈降低趋势。在此基础上,提出了有针对性地改善灌溉方式、提高耕作技术、结合灌水淋洗使用化学改良剂以及修建排水设施等河套灌区治理盐碱化措施。     

ICA结合纹理特征的SVM盐渍化信息提取研究

以渭干河-库车河三角洲绿洲为例,利用ETM+数据,探讨了该绿洲盐渍化土地覆盖信息的提取方法。提出了基于ICA与纹理特征的SVM复合的分类方法（简称ICA-T-SVM法）,通过此方法对该绿洲进行分类研究,并将分类结果与基于ICA的SVM法（简称ICA-SVM）、单源数据（光谱）SVM法、最大似然法（MLC）、神经网络法（Neural Network）分类结果进行定性和定量比较分析。研究结果表明：该方法能够有效地解决单数据源分类效果破碎、分类精度不高等问题,并对高纬输入向量具有较高的推广能力。总精度达到93.418 3%,比基于ICA的SVM法提高了3.412 3%,比单源信息的SVM分类法提高了3.423 7%,比最大似然法提高了4.979 6%,比神经网络法提高了7.714 4%,取得了良好的效果。与传统的分类方法的比较表明,文中所提出的分类方法具有明显的优越性和良好的前景,因此该方法更适合于遥感图像分类和盐渍化信息提取,是地物遥感信息提取的有效途径。     

Modelling water and salt transport in a soil–water–plant system under different groundwater tables

Salinization in a soil–water–plant system is an important environmental issue that has caused public concerns. In this study, field column experiments are conducted to study the transport of water and salt in soils affected by hydrologic circle and plant growth. A soil water and salt transport model (SWSTM) is developed and calibrated for predicting the behaviour of water and salt in a soil–water–plant system. The model takes into account water and solute uptake by crop roots and migration to groundwater. The experiment results demonstrate that the rise of the groundwater table enhances the movement of water and results in the accumulation of salt at a layer of 45 cm depth. With the decline of the groundwater table, the amount of accumulated salt increases correspondingly. The simulation results demonstrate that the SWSTM adequately predicts the water and salt transport in a soil–crop–plant system under different groundwater tables. The use of SWSTM will help to reveal the mechanism of water and salt transport in a soil–water–plant system. The SWSTM can also serve as a useful tool in evaluating the impact of agricultural activities and formulating efficient water management strategies in China.     

区域土壤盐渍化遥感监测研究综述

对国内外遥感监测土壤盐渍化发展情况作了介绍,对土壤盐渍化及其动态变化遥感监测方法进行了总结,数字图像处理将成为区域土壤盐渍化遥感监测研究的主要手段,土壤盐渍化是一个世界性的问题,应将遥感琢遥感图像处理的最新成果充分运用到盐渍土监测研究中,为盐渍土治理与农业可持续发展提供信息保障。     

Chloride and total phosphorus budgets for Lake Nipissing,headwater of Lake Huron,Ontario, Canada

Anthropogenic sources of total phosphorus (TP) and chloride (Cl^?) to lakes and rivers have been issues of concern for many decades in the Great Lakes Basin with northern Boreal Shield headwater tributaries less well studied. In the Sturgeon River – Lake Nipissing – French River basin, a headwater basin of Georgian Bay, Lake Huron, water quality monitoring of major inflows to Lake Nipissing, the third largest inland lake located entirely within Ontario, is only available from the mid-1960s to the 1990s. During the period of 2015–2018, we conducted monthly water quality surveys of major and minor inflows for two water years and have generated the first chloride (Cl^?) and total phosphorus (TP) elemental budgets for the lake. Review of available long-term concentration data indicate decreasing TP concentrations by decade in major inflows, but select inflows continue to exhibit concentrations above provincial objectives, including inflows from agricultural areas that are no longer part of provincial monitoring programs. Some inflows also show high average Cl^? concentrations with potential influences (e.g., road salt, agricultural activities) to stream water quality throughout the year. Water and elemental budgets indicate that while specific runoff (l/s/km²) is quite similar across contributing catchments, yields of Cl^? and TP (kg/ha/yr) are disproportionately higher in catchments with urban and agricultural activities. While uncertainties in the water balance and elemental yields remain, this first effort to quantify annual elemental budgets of Lake Nipissing highlights the need to develop community-based, spatially distributed water quality surveying for long-term ecosystem monitoring and future planning.     

Seasonal changes of fertilizer impacts on agricultural drainage in a salinized area in Adana, Turkey

Seasonal changes in the impacts of fertilizer on the composition of agricultural drainage water were examined by analyzing the ⁸⁷Sr/⁸⁶Sr isotope ratio and chemical composition of drainage water samples. Samples of drainage water were taken from the main drainage canals of the Lower Seyhan Irrigation Project, at sites designated as D10, D11, and D12. Plots of ⁸⁷Sr/⁸⁶Sr vs. 1/Sr indicated that the ⁸⁷Sr/⁸⁶Sr ratio of drainage water was positively related to those of fertilizer and irrigation water. The origins of Sr in two of the end-components were fertilizer and irrigation water. The data from the end-drain in winter suggested that the origin of Sr in the third end-component was fossil seawater. Analysis of a mixing model incorporating these three end-components showed that the origins of Sr in drainage differed markedly between summer and winter. Fertilizer made the greatest contribution to Sr in drainage water both in summer and winter, contributing 38-72% of total Sr in summer and 64-87% of total Sr in winter. In summer, fertilizer contributed 72% of total Sr in drainage water in D12, 44% in D10, and 38% in D11. This result implies that fertilizer was applied excessively at the D12 site. In winter, seawater accounted for 10% of Sr in drainage water in D12, whereas it accounted for 19-27% of Sr in drainage water in D10 and D11. Therefore, at least 70% of the salt in drainage water originates from fertilizer and irrigation water. At this study site, the salt originating from seawater is replaced by that from fertilizer and irrigation water, due to intensive agricultural management. The study site is a delta that lay on the ocean subsurface at least 3000 years ago, and therefore, was originally a primary salinization area. This result suggests that anthropogenic secondary salinization progressed over time via fertilizer and irrigation applications.     

黑龙江引嫩扩建骨干工程运行后嫩左低平原次生盐碱化易发性预测

针对黑龙江引嫩扩建骨干工程运行后嫩左低平原土壤次生盐碱化易发程度问题,分析了嫩左低平原次生盐碱化的形成条件,指出次生盐碱化与包气带渗透性、地下水矿化度、地下水位埋深密切相关,参考DRAS-TIC方法给出了这三者的评分及其权重,进而利用SPSS软件构建地下水矿化度与地下水位埋深、大气降水量及蒸发量的多元线性回归方程,据此预测了引嫩扩建骨干一期工程运行后2015年9月嫩左低平原处的地下水矿化度。构建了嫩左低平原地区土壤次生盐碱化易发性计算公式,计算了2015年9月各监测点的易发性数值,进而划分出土壤次生盐碱化易发性分区,为下一步有效预防土壤次生盐碱化奠定了基础。     

典型盐渍化土壤偏振反射高光谱特征与模型分析

盐渍化土壤不仅对农业生产产生巨大的威胁,而且对生态环境也构成了巨大的破坏.本文以吉林省西部盐渍化土壤为例,将遥感信息中的偏振信息和高光谱信息相结合,通过对吉林省西部盐渍化土壤光谱特征的获取,选择合适的波段,建立普适的模型,并进行科学验证.研究表明,盐渍化土壤的偏振高光谱信息与其理化属性参数具有一定的相关关系,并具有规律性,尤其是土壤线模型,利用土壤线进行建模,可以预测土壤的盐碱化程度.     

The changing face of the Ethiopian rift lakes and their environs: call of the time

The Ethiopian rift is characterized by many perennial rivers, and a chain of lakes that vary in size, and hydrological and hydrogeological settings. The water resources of the Rift lakes are one of the focal points for large‐scale development in Ethiopia over the last few decades. Some of the lakes and their influent rivers are used for irrigation, soda abstraction, fish farming and recreation, and also support a wide variety of endemic birds and wild animals. Ethiopia's major mechanized irrigation farms and commercial fishery are confined within the Rift region. A few of the lakes have shrunk in surface area because of excessive water abstractions, while others have expanded because of increased surface run‐off and groundwater inflows from percolated irrigation water. Excessive land degradation, deforestation and over‐irrigation have changed the hydrological setting of a few Rift lakes. Human activities, in combination with changes in climate and geology, have influenced the hydrological setting and the water quality of the lakes, with the salinity and major ion composition dramatically changed in some of them. This study tries to address the challenges associated with development of these surface‐water resources, focusing on environmental problems arising over the past few decades on three lakes (Abiyata, Beseka and Ziway) situated along the tectonically active Rift floor. The methods utilized in this study include field hydrological and hydrogeological mapping, supported by aerial photographs and satellite imagery interpretations, as well as hydrometeorological and hydrochemical data analysis, and catchment hydrological modeling. A converging‐evidence approach was adapted to reconstruct the temporal and spatial variations of the lake water levels and surface areas. The study results revealed that the major changes in the Rift Valley are related primarily to recent improper use of water from the large rivers draining the Rift Valley floor and the lake catchments, and from direct lake water abstractions aggravated intermittently by climatic and land use changes. These changes represent grave environmental consequences on the fragile Rift ecosystem that demands urgent intervention in the context of an integrated, basin‐wide water management approach. This study emphasizes lake water level changes and human influences on these changes. It also assesses human interactions and water quality changes, including land use changes and environmental repercussions on the lakes, as well as providing recommendations on how these issues should be addressed.