新疆玛纳斯河流域的土地利用与退化问题

玛纳斯河流域山地、平原、沙漠、湖泊俱全，土地利用类型有8个一级类型及40个二级类。20世纪50年代以来，在山前水、土、光热组合优良地区开展大规模水土开发建设，使区内的土地资源得以充分利用，土地开发利用率达40％以上。然而，不合理的土地利用已经导致土地退化，其主要类型有土地荒漠化、耕地土壤贫瘠化、土壤次生盐渍化、土地沙漠化、水土流失、土地污染等6种。据区域土地利用特点与退化类型及原因，提出了合理利用土地与防止土地退化的5条措施，以确保玛河流域土地永续利用与持续发展。     

德州盐渍土改良与开发利用研究

德州市是我国北方土壤盐碱化和次生盐渍化分布最典型的地区之一,20世纪50至60年代就率先在全国进行土壤改良试验,改良成果突出。但是在投入巨资进行工程建设的同时,次生盐渍化现象并没有得到根本性改变,反而出现反弹现象。运用地学原理分析了研究区土壤盐碱化和次生盐渍化的分布和成因,总结出区域盐碱地整治和改良措施,运用生态学和景观生态学原理提出研究区盐碱资源开发利用的经济、社会和生态价值,以及盐碱资源可持续利用的新思路和建议。     

喀什市土地利用对生态环境的影响分析

喀什市土地利用总体规划实施以来,土地利用变化对生态环境的影响显著,文章从土地沙化、土壤盐渍化、水环境情况、土壤地膜污染、土壤肥力、生物多样性、沙尘暴、大气污染物时空分布特征等方面分析了喀什市土地生态环境现状,通过分析土地利用规模、结构和布局及基础设施建设、土地开发整理和重大生态建设工程对生态环境的影响,提出喀什市生态改善目标及用地建议.     

典型绿洲农业生态与环境演化中主要问题及对策：以玛纳斯绿洲为例

在阐述了典型绿洲农业生态与环境基本特点的基础上，揭示了其演化规律。具体分析了玛纳斯绿洲农业生态与环境的主要问题，土壤次生盐渍化，土地沙化，草场退化，环境污染加重等，针对问题提出了具体的人工调控对策。     

新修农田土壤培肥技术试验研究

黄土丘陵区土地资源主要以坡地形式存在，近年来声势浩大的坡改梯工程使一部分山坡地变为层层梯田，水土保持率明显提高，而如何进行新生土层的土壤培肥，又是该工程的重要课题。作者对当地近几年土壤培肥技术试验进行了研究。以期提高土地资源的利用率。     

石河子垦区农业生态环境的主要问题及其对策

文章分析了石河子垦区农业生态环境的主要现状问题:土壤次生盐渍化、耕地板结化肥力下降、土壤侵蚀与土地沙化、草场退化、农业生态系统结构欠优功能弱和农业环境污染加重。针对上述问题,提出了具有操作性的整治对策。     

青海环境的若干问题与整治对策

青海存在的环境问题较多，随着国家中西部地区经济发展战略的实施，将对表少经济持续发展与环境问题有着十分密切的关系。青海环境问题主要是草地退化、水土流失、土地荒漠化、旱灾、雪灾、风灾、土地次盐渍化和沼泽化、环境污染、气候旱化以及冰川退缩。因此，如何治环境，对青海经济发展和资源开发非常重要。     

新疆典型绿洲盐渍化土壤特征分析

土壤盐渍化是影响区域生态环境稳定性以及制约农业生产发展的重要因素。对土壤特性进行研究是开展精细农业实践必要的基础研究。本文采用传统统计学方法、相关分析与主成分分析方法,分析新疆典型盐渍化区域渭-库绿洲的土壤含盐量、电导率、TDS、pH值、含水量及主要盐基离子的特征值以及相互之间的关系。结果显示,研究区土壤pH值相对稳定;土壤含盐量具有不均匀分布特征;土壤盐分的分布是有较强的表聚特征。绝大多数时间,矿化度与电导率,电导率与含盐量,SO_4~(2-)、Na~+、Cl~-等离子与表层土壤含盐量之间具有较好的正相关关系,而其他各指标之间的相关关系不太明显。研究区土壤中硫酸盐、氯化物在表层积聚相对强烈;土壤盐渍化类型是属于氯化物型,研究区土壤还在聚盐状态。     

包头市达茂旗土地退化现状及其成因分析

通过对包头市达茂旗自然环境和社会经济状况的研究，得出其土地退化问题十分严重。主要表现为：风蚀沙化严重、土壤水蚀问题突出、草地退化趋势加剧、耕地肥力下降相当普遍、盐渍化问题不容忽视。针对土地可持续利用中存在的主要制约因素进行了深入分析，得出长期的自然和人为因素的综合干扰是导致土地退化的主要原因，以期为各级决策部门提供参考。     

我国西北地区土地盐渍化与水资源利用

西北干旱的气候环境,不合理的水资源规划和利用是导致耕地盐渍化的根本原因,土地盐渍化给地方农业带来了严重影响。本文结合我国西北地区土地盐渍和农业灌溉状况,对水资源的利用问题作了分析。     

Autonomous real-time adaptive management of soil salinity using a receding horizon control algorithm: a pilot-scale demonstration

Soil salinization is a potentially negative side effect of irrigation with reclaimed water. While optimization schemes have been applied to soil salinity control, these have typically failed to take advantage of real-time sensor feedback. This study incorporates current soil observation technologies into the optimal feedback-control scheme known as Receding Horizon Control (RHC) to enable successful autonomous control of soil salinization. RHC uses real-time sensor measurements, physically-based state prediction models, and optimization algorithms to drive field conditions to a desired environmental state by manipulating application rate or irrigation duration/frequency. A simulation model including the Richards equation coupled to energy and solute transport equations is employed as a state estimator. Vertical multi-sensor arrays installed in the soil provide initial conditions and continuous feedback to the control scheme. An optimization algorithm determines the optimal irrigation rate or frequency subject to imposed constraints protective of soil salinization. A small-scale field test demonstrates that the RHC scheme is capable of autonomously maintaining specified salt levels at a prescribed soil depth. This finding suggests that, given an adequately structured and trained simulation model, sensor networks, and optimization algorithms can be integrated using RHC to autonomously achieve water reuse and agricultural objectives while managing soil salinization.     

Preliminary Strategic Environmental Assessment of the Great Western Development Strategy: Safeguarding Ecological Security for a New Western China

The Great Western Development Strategy (GWDS) is a long term national campaign aimed at boosting development of the western area of China and narrowing the economic gap between the western and the eastern parts of China. The Strategic Environmental Assessment (SEA) procedure was employed to assess the environmental challenges brought about by the western development plans. These plans include five key developmental domains (KDDs): water resource exploitation and use, land utilization, energy generation, tourism development, and ecological restoration and conservation. A combination of methods involving matrix assessment, incorporation of expert judgment and trend analysis was employed to analyze and predict the environmental impacts upon eight selected environmental indicators: water resource availability, soil erosion, soil salinization, forest destruction, land desertification, biological diversity, water quality and air quality. Based on the overall results of the assessment, countermeasures for environmental challenges that emerged were raised as key recommendations to ensure ecological security during the implementation of the GWDS. This paper is intended to introduce a consensus-based process for evaluating the complex, long term pressures on the ecological security of large areas, such as western China, that focuses on the use of combined methods applied at the strategic level.     

Combined use of GIS and environmental indicators for assessment of chemical, physical and biological soil degradation in a Spanish Mediterranean region

Soil is one of the main non-renewable natural resources in the world. In the Valencian Community (Mediterranean coast of Spain), it is especially important because agriculture and forest biomass exploitation are two of the main economic activities in the region. More than 44% of the total area is under agriculture and 52% is forested. The frequently arid or semi-arid climate with rainfall concentrated in few events, usually in the autumn and spring, scarcity of vegetation cover, and eroded and shallow soils in several areas lead to soil degradation processes. These processes, mainly water erosion and salinization, can be intense in many locations within the Valencian Community. Evaluation of soil degradation on a regional scale is important because degradation is incompatible with sustainable development. Policy makers involved in land use planning require tools to evaluate soil degradation so they can go on to develop measures aimed at protecting and conserving soils. In this study, a methodology to evaluate physical, chemical and biological soil degradation in a GIS-based approach was developed for the Valencian Community on a 1/200,000 scale. The information used in this study was obtained from two different sources: (i) a soil survey with more than 850 soil profiles sampled within the Valencian Community, and (ii) the environmental information implemented in the Geo-scientific map of the Valencian Community digitised on an Arc/Info GIS. Maps of physical, chemical and biological soil degradation in the Valencian Community on a 1/200,000 scale were obtained using the methodology devised. These maps can be used to make a cost-effective evaluation of soil degradation on a regional scale. Around 29% of the area corresponding to the Valencian Community is affected by high to very high physical soil degradation, 36% by high to very high biological degradation, and 6% by high to very high chemical degradation. It is, therefore, necessary to draw up legislation and to establish the policy framework for actions focused on preventing soil degradation and conserving its productive potential.     

INTERNATIONAL MANAGEMENT OF THE RIO GRANDE BASIN THE UNITED STATES AND MEXICO1

ABSTRACT. Despite radical differences in water laws, water management agencies, approaches to water planning, and financial resources, Mexico and the United States forged a common program to manage water and related land on the Rio Grande. Actions of Rio Grande Commissions related to stream gaging, boundary definition, and multiple-purpose construction projects are among the more successful international water-management efforts in the world. Cost-sharing arrangements promoted rapid completing of international works. However, joint action accomplished only part of expectations. International developments were competitive rather than complementary until basin water appropriation was virtually complete. Moreover, Commissions were not empowered to consider long-range competitive water needs, or regional water requirements, throughout the basin. International groundwater use coordination does not exist. International structures produce less than anticipated benefits. Hydroelectric generators are financial liabilities, irrigated acreage exceeds dependable streamflow, and soil salinization is experienced. Unanticipated environmental changes occurred in every major program. The Rio Grande experience points to the need for society to specify goals to which the use of water should contribute and to specify priorities for water use among different sectors of river basins and various segments of society.     

Spatial Variation of Soil Salinity in the Mexicali Valley, Mexico: Application of a Practical Method for Agricultural Monitoring

The degradation of irrigated lands through the process of soil salinization, or the buildup of salts in the soil, has hampered recent increases in agricultural productivity and threatens the sustainability of large-scale cultivation in critical agricultural regions of the world. Rapid detection of soil salinity on a regional basis has been identified as key for effective mitigation of such land degradation. The ability to detect regional patterns of soil salinity at an accuracy sufficient for regional-scale resource management is demonstrated using Landsat 5 Thematic Mapper (TM) imagery. A case study of the Mexicali Valley of Baja California, Mexico was selected due to the region's agricultural significance and concern for future soil salinity increases. Surface soil salinity was mapped using georeferenced field measurements of electrical conductivity (EC), collected concurrently with Landsat 5 TM imagery. Correlations between EC measurements and common indices derived from the satellite imagery were used to produce a model of soil salinity through regression analysis. Landsat band 7, TNDVI, PCA 1, Tasseled Cap 3 and Tasseled Cap 5 were found to offer the most promising correlations with surface soil salinity. Generally low levels of soil salinity were detected, however, distinct areas of elevated surface salinity were detected at levels potentially impacting sensitive crops cultivated within the region. The difficulty detecting low levels of salinity and the mid-range spatial resolution of Landsat 5 TM imagery restrict the applicability of this methodology to the study of broad regional patterns of degradation most appropriate for use by regional resource managers.     

基于贝叶斯网络分类的土壤盐渍化遥感监测

贝叶斯网络是一种将贝叶斯概率方法和有向无环图的网络拓扑结构有机结合的概率模型.采用贝叶斯网络分类对具有典型干旱特征的库车县土壤盐渍化情况进行监测,首先应用条件独立性测试原理建立贝叶斯网络结构,把研究区遥感数据进行离散化,然后应用贝叶斯定理作为分类原则,将每个像元分为像元最大概率的类别.研究结果表明该方法来分类6种地类的整体分类精度达到96%,并为该区盐渍地面积,空间分布等特征监测提供较好的依据.     

Farmers’ Perceptions of Land Degradation and Their Investments in Land Management: A Case Study in the Central Rift Valley of Ethiopia

To combat land degradation in the Central Rift Valley (CRV) of Ethiopia, farmers are of crucial importance. If farmers perceive land degradation as a problem, the chance that they invest in land management measures will be enhanced. This study presents farmers’ perceptions of land degradation and their investments in land management, and to what extent the latter are influenced by these perceptions. Water erosion and fertility depletion are taken as main indicators of land degradation, and the results show that farmers perceive an increase in both indicators over the last decade. They are aware of it and consider it as a problem. Nevertheless, farmers’ investments to control water erosion and soil fertility depletion are very limited in the CRV. Results also show that farmers’ awareness of both water erosion and soil fertility decline as a problem is not significantly associated with their investments in land management. Hence, even farmers who perceive land degradation on their fields and are concerned about its increase over the last decade do not significantly invest more in water erosion and soil fertility control measures than farmers who do not perceive these phenomena. Further research is needed to assess which other factors might influence farmers’ investments in land management, especially factors related to socioeconomic characteristics of farm households and plot characteristics which were not addressed by this study.     

HYDROLOGICAL EFFECTS OF AN UNCONTROLLED FLOWING WELL,RED RIVER VALLEY,NORTH DAKOTA,USA1

ABSTRACT: In areas of the Red River Valley that overlie permeable Paleozoic sediments, wetlands and salinization have developed where unregulated flowing wells discharge brackish water. Field data were collected to assess the fate of water and salt from a well 25 km northwest of Grand Forks. Drilled during the drought of the 1930s, discharge was used to replenish water in a small oxbow pond used by livestock. The unregulated well discharges about 56 m³/day, measured since 1993. This discharge exceeds ground water flow from the site, thereby forming a ground water mound with a maximum height of 1 m and a diameter of about 300 m. Most soil and underlying sediments near the well have a hydraulic conductivity of 0.3 m³/day. Flow net analysis suggests that less than 25 percent infiltrates, with the remaining water lost to surface flow and evapotranspiration (ET). Evapotranspiration and slow infiltration has led to increased salinization, with shallow soils exhibiting EC to 500 milliSiemens/m. The most pronounced soil salinization occurs along the margins of the oxbow pond and meander scars. Wetland vegetation with low diversity comprises three zones, with species associations similar to those of closed basin prairie potholes to the west.