Remote sensing and GIS for identification of suitable sites for soil and water conservation structures

Formulation of a proper watershed management plan requires reliable and up‐to‐date information about various factors such as morphologic (size and shape of the watershed, drainage parameters, topography), soil and their characteristics, land use, and land cover, etc. that affect the behavior of a watershed. Satellite based remote sensing technology and GIS meets both the requirements of reliability and speed and are ideal tools for generating spatial information needs. In this study, a locale‐specific watershed development plan was generated for the case study area of a small agricultural watershed of Karso, Hazaribagh, India using remote sensing and GIS techniques. Indian Remote Sensing Satellite (IRS‐1C), Linear Imaging Self Scanner (LISS‐III) satellite data along with other datasets, e.g. existing maps and field observation data have been utilized for generating a land use/land cover map and to extract information on morphological parameters (bifurcation ratio, elongation ratio, drainage density, ruggedness number, relief ratio, and circulatory ratio) and other thematic maps which are an essential prerequisites for watershed development. Morphological parameters of subwatersheds were derived to understand its usefulness for surface water development. The conceptual framework for plan and site suitability mapping for soil and water conservation structures is developed and subsequently, these parameters were integrated with other thematic information viz., land use/cover, drainage, slope, and soil in the GIS environment to arrive at a decision regarding a suitable site for having soil and water conservation structures ( nala bund , check dam, and percolation tank) in its place adopting a holistic approach. Copyright © 2010 John Wiley & Sons, Ltd.     

Land use and soil conservation strategies for potentially highly erodible soils of central-eastern Nigeria

In areas susceptible to erosion, there is the need for a comprehensive soil conservation programme so as to be able to prevent catastrophic soil erosion problems. The absence of such a programme in central eastern Nigeria, that has a total land area of 20 000 km², necessitated the drawing up of a soil conservation strategy for the area. The aim was to provide information for better land-use planning and proper environmental and soil management. To achieve this, topographic, soil and landform maps of the area at the scale of 1:50 000 were used to delineate into slope land units, viz: 0–4 per cent, <4 per cent, drainage basins and headwaters. These slope units and estimated soil erosion hazard units using the revised universal soil loss equation (RUSLE) were employed to form a general purpose land classification based on the USDA land capability classification and FAO framework on land evaluation.The soil loss tolerance of the area falls between 1·16 and 1·30 Mg ha⁻¹ yr⁻¹, while the erosion hazard units are considered generally suitable for the various land utilization types, with a number of limitations the main ones being erosion and waterlogging. The soil conservation measures proposed involved the application of bioenvironmental processes in the area and appropriate watershed management. The techniques proposed are those based on low input technology, affordable by rural farmers. It is concluded that these soil conservation measures will be adequate for sustainable agricultural production in the area. Copyright © 1999 John Wiley & Sons, Ltd.     

Interactions between soil conservation and dryland farming of heterogeneously eroding areas in Loess Hills,China

The unidirectional impacts of soil conservation on dryland farming and local livelihood have been well studied. However, there are gaps in literature regarding the interactions among factors, such as labor force and financial capital, in response to soil conservation, as well as the influence of such interactions on the relationships between environmental projects and agricultural development. By combining the Chinese Soil Loss Equation (CSLE) model and statistical analyses, this study investigated the spatio-temporal characteristics of soil erosion while also identifying the controlling factors that affect crop and livestock farming. The aim was to reveal how these factors interacted to influence agriculture in two case study areas between 2000 and 2017. The results showed that soil erosion substantially declined as a consequence of soil conservation, while the output from crop farming increased, indicating that there was a synergy between soil conservation and dryland farming in both the districts, over time; and factors facilitating crop farming, such as labor force, agricultural machinery, and irrigation, appeared to exert an adverse effect on livestock farming in both areas, implying a tradeoff between livestock and crop farming in the context of programs such as the Grain for Green Program (GGP) in the Loess Hills. Such a tradeoff is a result of the competition for cropland and labor that exists due to grazing prohibition and rural-urban migration. Therefore, policy-related resolutions are required to address the land use conflicts and migration-related rural labor losing due to implementation of the GGP in the Loess Hills.     

Mechanical soil conservation with contour ridges: Cure for,or cause of,rill erosion?

Based on the results of an erosion damage assessment in Southern Zimbabwe, where mechanical conservation work has been carried out since the 1940s, this paper describes the impact of mechanical conservation systems on processes leading to rill erosion. In a study of a catchment area, it was found that influxes of water from roads and waterways as well as contour ridges that were originally designed to control rill erosion had a major role in the formation of rills. Existing rills and depressions which cause water concentration, siltation of contour drains and overflowing of contour ridges were the main factors leading to excessive rill erosion. The study showed that particularly during a highly erosive year like 1992/93, the damage due to rill erosion can be excessive, causing an abrupt degradation. It is concluded that the present conservation system is insufficient to control rill erosion effectively and is often the cause of this erosion. Effective control of rill erosion is a pre-condition for optimal implementation of land management systems such as conservation tillage. Therefore, an integrated approach to land husbandry must be developed jointly with farmers and promoted in order to improve crop production and sustainable management of natural resources. This should consider improved mechanical conservation as well as agronomic and biological soil and water conservation techniques.     

丹江口库区2010-2020年土壤保持功能时空特征及其影响因素

[目的] 评估丹江口流域土壤保持功能时空变化及其影响因素,为南水北调中线工程水源地水土流失治理模式的确立以及流域水土保持与生态系统安全管理提供科学依据。[方法] 采用InVEST模型和地理探测器方法分别对丹江口库区2010,2015和2020年土壤保持功能时空变化特征及其影响因素进行定量分析。[结果] ①丹江口库区2010—2020年实际土壤侵蚀量呈递减趋势,土壤侵蚀等级逐渐向微度侵蚀转变,且各年间空间分布趋势基本一致。②丹江口库区2010,2015和2020年土壤保持量分别为6.25×10⁹ t,6.62×10⁹ t和7.12×10⁹ t,呈逐步上升的趋势,表明库区土壤保持功能不断增强。③不同海拔范围土壤保持功能具有差异,较高海拔地区土壤保持量较高（如东北部伏牛山、西部秦岭、西南部武当山）,低海拔区土壤保持量较低（如丹江口水库周边地区）。不同土地利用类型土壤保持能力亦差异较大,以林地最高,其次为灌草地、园地和耕地。④地理探测器分析结果显示,丹江口库区土壤保持功能变化主要受地形因子的影响。[结论] 近年来丹江口库区土壤保持功能总体趋势持续好转,部分区域土壤保持量仍较低,未来应继续推进退耕还林（草）工程建设,重视和保护土壤保持能力较强的林地和灌草地,从而增强库区土壤保持功能。     

红壤丘陵区农户水土保持投资行为研究--以江西省余江县为例

通过对余江县3个乡镇的农户访谈式调查,对农户水土保持行为机理进行了分析。研究表明农户兼业行为、传统生产习惯、农业经营规模、农业劳动力状况、水土流失现状与家庭经济条件等因素对农户水土保持行为有较大影响。通过相关性分析,建立了多元线性回归模型。模型运行结果表明,农户水土保持行为主要受到非农收入比例、从事农业生产的时间、从事农业人口数量、经营土地面积、水土流失减产损失、家庭人均收入以及距离城市远近等因素的影响。非农收入比重高的农户,水土保持投入的积极性不高。农业人口多的农户,或者受家族传统影响较勤劳的农户,其水土保持投资也多。据此,提出了激励农户水土保持投资行为和改善水土流失治理现状的相关建议。     

Land evaluation and conservation of semiarid agrosystems in Zaragoza (ne Spain) using an expert evaluation system and GIS

In the area around Zaragoza, agrosystems are very fragile. Water is the main limiting factor for cultivation. Annual rainfall does not exceed 350mm, and the occurrence of convective storms with short and intense periods of very heavy rainfall greatly increases the danger of water erosion. Also, the mostly squeletic soils in this sparsely vegetated area are prone to erosion. In this semiarid environment, soil essentially constitutes a non-renewable resource, and therefore conservation of these agrosystems is an important issue and a serious environmental concern. Effective land management and soil conservation strategies require a variety of information and maps. In this paper, an expert land evaluation system (MicroLEIS) along with a geographic information system (IDRISI) are used to develop a computerized spatial database in order to suggest suitable land management strategies for environment conservation.     

东北水保工程项目区水土保持效益评价

在国家农业综合开发东北黑土区水土流失治理一期工程区内,选取新型大垄、垄向区田(3°和5°)、3°垄沟深松、改垄、梯田、地埂、草地、林地共8个不同的水土保持措施地块作为试验小区,以传统3°和5°顺坡垄作为对照小区,开展全年水土保持监测,并以此进行了田块尺度上的各项水土保持措施的效益分析。研究结果表明,水保工程措施总体优于水保耕作措施,在耕作措施中新型大垄密植水保效果最佳。各项措施水土保持效益排序为:草地>林地>新型大垄>改隆>梯田>地埂>深松>3°区田>5°区田。新型大垄、区田和深松措施水保作用具有时效性。     

黑土坡耕地不同水土保持措施的土壤水蚀特征研究

针对北方干旱地区坡耕地严重的水土流失问题,采取垄向区田、深松、横坡种植、免耕播种等水土保持耕作措施,于2010年,以黑龙江省齐齐哈尔市东兴村5°坡耕地径流场为研究对象,研究了不同耕作措施对地表径流、土壤侵蚀和降雨入渗的影响。结果表明,这几种水土保持耕作措施均有不同程度的减流减沙作用,其中横坡种植效果最为明显,地表径流量和土壤流失量较常规耕作分别减少了92%和90%,稳定入渗率较常规耕作提高了41.2%。不同耕作措施的径流系数过程线的变化、径流含沙率变化以及产流量、产沙量的变化均符合横坡免耕>横坡种植>深松+区田>垄向区田>少耕深松>免耕>常规耕作>裸地这一变化规律。     

紫色土区小流域土壤保持服务功能的空间分布特征

[目的]分析不同坡度、土壤类型、土地利用下的土壤保持服务功能分布,为减少土壤流失和改进土地利用规划提供科学依据。[方法]结合修正通用土壤流失方程(RUSLE)和GIS技术,以曲水河小流域为典型研究区,基于DEM、土壤、土地利用等基础数据,分析了研究区土壤保持服务功能的分布现状及影响因素。[结果](1)该流域土壤保持总量为1.10×107 t/a,单位面积土壤保持量为384.74t/(hm2·a),具有较高的生态系统服务功能重要性;(2)土壤保持服务功能总体呈现从河谷阶地逐渐向周边丘陵坡地递增的空间分布特征;(3)强烈及以上侵蚀强度区、8°~25°的坡度区、耕地、钙质紫泥田区和红棕紫泥土区应为土壤保持工作的热点区域。[结论]不同坡度、土壤类型、土地利用类型下土壤保持服务功能差异显著,可以通过改良土壤、提高植被覆盖和采取土壤侵蚀防治措施提高土壤保持服务功能水平。     

延河流域典型治理阶段的土壤保持功能时空变化及驱动因素分析

[目的]探究黄土高原所进行的退耕还林(草)及治沟造地等典型治理工程的生态系统水土保持功能时空变化及其驱动因素,对于黄土高原进一步发展具有重要指导作用。[方法]通过构建延河流域InVEST生态服务功能模型和地理探测器的方法,在验证的基础上,研究了典型治理阶段流域的生态系统土壤保持功能。[结果](1)在时间变化上,与退耕还林前(1990—2000)相比,退耕还林期(2000—2010)和退耕还林+治沟造地期(2010—2017)的多年平均土壤保持量分别增加了32.29%,55.61%,年均增加4.92×10⁶ t;(2)在空间分布上,林草地和治沟造地的面积增加区域与土壤保持量增加区域具有一致性,治沟造地工程使得延河流域耕地整体的土壤保持能力提高,单位造地面积的土壤保持量增加7 t/hm²。土壤保持量随坡度、高程的增加呈现先增加后减少的趋势,在海拔1 200～1 500 m,坡度15°～25°范围内土壤保持总量占年总土壤保持量比例较高。[结论]土地利用类型的变化是影响土壤保持空间分布格局的主要驱动因子。延河流域土壤保持功能时空变化的驱动因素分析为黄...     

Integration of biophysical and socio‐economic factors to assess soil erosion hazard in the Upper Kaligarang Watershed,Indonesia

Soil erosion is one form of land degradation, which is caused by the interacting effects of numerous factors such as biophysical characteristics and socio‐economic condition of a particular watershed. Previous erosion studies focused on the use of soil erosion models (e.g. USLE, EUROSEM, SLEMSA etc.), which have been developed under local conditions (e.g. United States, Europe, Africa, etc) and mostly use only biophysical factors as inputs to the models. In this study, a methodology that integrates both biophysical and socio‐economic aspects into a framework for soil erosion hazard assessment using principal component analysis (PCA) is described. The analysis is done at the land unit level. With the particular conditions of the study area that is characterized by Inceptisols and Alfisols soil types, nine different land uses with mixed vegetation and forest area dominant in the steep slope, high annual rainfall (>2500 mm), high population with mostly low income and low education, were considered. These were used in formulating a soil erosion hazard index (EHI) equation which relates a number of key factors consisting of biophysical and socio‐economic variables, namely soil texture, slope steepness, land cover, soil conservation practices, income and farmers' knowledge. Weighting and scoring of these key factors were used to develop the EHI equation and to calculate an index value of erosion hazard for every land unit. Results indicate that more than 60% of the area has erosion hazard ranging from moderate to very severe, and most of the land units with high erosion hazard were found at the mountain areas. It was also found that erosion hazard was severe in areas with high silt content, followed by high rainfall and steep slope, low crop cover without any soil conservation practices coupled with lack of awareness on soil erosion and low income. The key factors identified and level of erosion hazard obtained can be used to formulate conservation measures in critical areas which are prone to soil erosion. Copyright © 2007 John Wiley & Sons, Ltd.     

水土保持与绿水资源保护

绿水概念是由瑞典斯德哥尔摩国际水资源研究所水文学家Falkenmark于1995年首次提出的,它拓宽了传统水资源的范畴,更新了水资源的思维,引起科学界对水资源概念和水文功能的重新思考。在水资源越来越匮乏的严峻情况下,从绿水概念出发,可以看出"水土保持"概念的全面性,也更加明确了保水的思路和方法,为全面做好水土资源保护提供了理论基础。水土保持中"保水"的对象就是绿水,水土保持工程措施可以增加绿水比例,林草措施可以储蓄绿水,耕作措施可以提高绿水利用效率。应完善保水评价体系,加强绿水资源管理,发展保水技术,完整地宣传水土保持概念,树立完整的水土保持意识。     

保护性耕作对黄土高原南部地区小麦产量及土壤理化性质影响

以1992年设置于山西省临汾市尧都区的保护性耕作试验基地为基础,研究了长期保护性耕作对旱地小麦产量、土壤理化性质及剖面水分含量的影响。结果表明,11年免耕覆盖和15年免耕覆盖分别比传统耕作平均增产192%和276%; 丰水年份增产率为52%和117%,而干旱年份增产率高达850%和976%,表现为实施保护性耕作年限越长、越是干旱,保护性耕作的增产效果越显著。保护性耕作能降低土壤容重,增加土壤孔隙度,提高土壤剖面水分含量和土壤贮水量,提高表层010 cm土壤有机质、碱解氮和速效钾含量, 但不利于有效磷含量的提高。11年免耕覆盖和15年免耕覆盖,表层010 cm土壤有效磷含量比传统耕作降低68和63 mg/kg,降低了561%和519%,应注意磷肥的施用。     

Soil and water conservation projects and rural livelihoods: options for design and research to enhance adoption and adaptation

This paper synthesizes the findings of a workshop which sought to consider the issues of poor uptake, adoption and adaptation of soil and water conservation techniques by farmers post‐project by examining the experiences of projects which had research and extension elements. Critical factors contributing to the adoption and adaptation of soil and water conservation techniques by farmers are identified as

• a more flexible approach and which enables learning within projects;
• a process rather than output driven approach to soil and water conservation;
• demonstration of immediate and tangible benefits of soil and water conservation to farmers (production, income, risk‐minimization); and
• avoiding a narrow focus on soil and water conservation—alternatives are ‘better land husbandry’ or ‘sustainable rural livelihoods’ approaches.

A number of areas are identified as priorities for further research which would aid the successful adoption of sustainable agricultural techniques and which should guide future research, development and extension, bringing more sustained benefits to farmers, particularly in humid and subhumid hillside regions. Copyright © 2000 John Wiley & Sons, Ltd.     

Determinants for adoption of physical soil and water conservation measures by smallholder farmers in Ethiopia

Adoption rates of soil and water conservation measures remain below the expected levels in Ethiopia despite the considerable investments in reducing land degradation and improving soil fertility. This constitutes one of the key research agendas in the country. This paper underscores the need for investigating the factors hindering or facilitating the adoption of soil and water conservation measures. The study results presented in this paper are based on cross-section data collected from 408 households in eastern Ethiopia, including field observations of 790 plots selected using a multi-stage sampling procedure. A multivariate probit model was employed to analyse the determinants of adoption of three soil and water conservation measures (stone bund, soil bund, and bench terracing) at the plot level. The study findings reveal that household, socioeconomic, and institution characteristics were the key factors that influenced the adoption of soil bund, stone bund, and bench terracing conservation measures. Furthermore, there was a significant correlation among the three soil and water conservation measures, indicating that the adoption of these measures is interrelated. In particular, the results show that there was a positive correlation between stone bunds and soil bunds. However, the correlations between bench terracing and stone bunds as well as bench terracing and soil bunds were negative (implying substitutability). These results imply that the Government and other relevant organizations that are responsible for reducing land degradation in order to increase agricultural production should support the establishment and strengthening of local institutions to facilitate the adoption of soil and water conservation measures.     

水土保持农业技术措施分类初探

为进一步完善我国水土保持农业技术措施的分类体系,并服务于研究与生产,在论述水土保持农业技术措施的概念、分类现状基础上,依据措施实施的方式、作用和目标,并结合农艺环节,将水土保持农业技术划分为以改变微地形为主的蓄水保墒技术、以提高土壤抗蚀力为主的保护性耕作技术和以增加植物覆盖为主的栽培技术3大类,等高耕作、沟垄种植、坑田、半旱式耕作、深耕翻、保墒、覆盖、深松、少耕、培肥土壤、合理配置作物、播种保苗、栽培13个亚类和等高耕作等44个型,以供参考.     

Reclaiming the erosion susceptible landscape of the Italian badlands for arable cultivation

During the last 50 years substantial tracts of the Italian badlands have been reclaimed for arable cultivation. It is a process that involves modelling the degraded clay landscape with bulldozers, often resulting in steep, unstable slopes. This work investigates the stability of reclaimed land in these erosion susceptible environments. Aggregate stability is used to assess the soil's erodibility with the aim of determining those physicochemical properties that govern the potential for erosion. Regression analysis demonstrates that the most significant variables in determining soil erodibility are the percentage of organic matter and the exchangeable sodium percentage (ESP). Threshold values of 1–2 per cent organic matter and 15 per cent ESP are presented above and below which, respectively, the soils attain a degree of stability. Reclaimed land is on the borderline of these thresholds and therefore represents a potential erosion hazard. However, the stability of reclaimed land was significantly higher than that of the badland parent material, ascribable to a decline in the ESP. The results are supported by a series of soil crust experiments using simulated rainfall in the laboratory. This investigation has implications for land management and landscape conservation. If the organic matter content of reclaimed land is maintained and the ESP reduced, then, when used in combination with other soil conservation techniques, erosion will be minimized. However, this implies that the badland landscape, and its diverse ecology and morphology, may have been permanently lost to agriculture and, as such, should be recognized as a threatened Mediterranean landscape. © 1998 John Wiley & Sons, Ltd.     

辽西土石质低山区不同土地利用类型土壤侵蚀特征研究

以辽西地区阜新县国华乡二道岭村的二道岭小流域7种土地利用类型为研究对象,通过布设自然坡面径流小区、分析小区径流泥沙观测数据、建立数学模型,探索了辽西土石质低山区坡地产流与侵蚀产沙的特征。研究表明:径流量与侵蚀量有着较好的相关性,二者呈对数函数关系;各种水保措施保土率的排序为水平坑(95.16%)>水平梯田(87.11%)>地埂植物带(83.99%)>横垄耕作(40.23%)>生态修复(29.07%)>顺垄耕作(18.22%)。辽西土石质低山丘陵区5°~15°的坡耕地应以修筑水平坑和水平梯田为主,人少地多、自然条件差的山区应以生态修复为主。