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Abstract

Military conflicts strongly affect agricultural activities. This has strong implications for people’s livelihoods when agriculture is the backbone of the economy. We assessed the effect of the Tigray conflict on farming activities using freely available remote sensing data. For detecting greenness, a Normalized Difference Vegetation Index (NDVI) was analyzed in Google Earth Engine (GEE) using Sentinel 2 satellite images acquired in the pre-war (2020) and during war (2021) spring seasons. CHIRPS data were analyzed in GEE to understand the rainfall conditions. The NDVI of 2020 showed that farmlands were poorly covered with vegetation. However, in 2021, vegetation cover existed in the same season. The NDVI changes stretched from -0.72 to 0.83. The changes in greenness were categorized as increase (2167 km²), some increase (18386 km²), no change (1.6 km²), some decrease (8269 km²), and decrease (362 km²). Overall, 72% of the farmlands have seen increases in green vegetation before crops started to grow in 2021. Scattered patches with decreases in vegetation cover correspond to irrigation farms and spring-cropping rain-fed farms uncultivated in 2021. There was no clear pattern of changes in vegetation cover as a function of agro-climatic conditions. The precipitation analysis shows less rainfall in 2021 as compared to 2020, indicating that precipitation has not been an important factor. The conflict is most responsible for fallowing farmlands covered with weeds in the spring season of 2021. The use of freely accessible remote sensing data helps recognizing absence of ploughing in crisis times.

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... Numerous publications address the origin of this war and potential paths to peace (Crisis Group 2021), which is largely out of scope of this work. The conflict has detrimental effects on the human population of the region, in relation to massacres, gender-based violence, health (Gesesew et al. 2021) and food situation (Weldemichel 2021;Biadgilgn et al. 2022). About three out of four Tigrayans live from farming (Regional State of Tigray 2018) and the region typically depends on local yields. ...
Article
During the 2021 conflict in Tigray (north Ethiopia) crop cultivation has been hampered by warfare. Oxen have been looted and killed, farm inputs and tools destroyed by Ethiopian and Eritrean soldiers. Farmers felt vulnerable out in the open with their oxen. To produce, farmers evaluated risks involved with ploughing and organised lookouts. Overall, a large part of the land had been tilled in difficult conditions, and crops sown that require minimal management, without fertiliser, what led to low yields. True Colour Composite images, produced from Sentinel satellite imagery show that smallholder irrigation schemes were operational. There was a shift from commercial crops to cereals. The situation in western Tigray was particular, as there has been ethnic cleansing of the population and often the 2020 rainfed crops had even not been harvested. Overall, our findings show that the Tigrayan smallholder farming system is resilient, thanks to community self-organisation, combining common strategies of agrarian societies in wartime: spatio-temporal shift in agricultural activities to avoid the proximity with soldiers and shifts in crop types. Rather unique is the relying on communal aid, while the blockade of the Tigray region made that outmigration and off-farm income were no options for the farmers.
... Numerous publications address the origin of this war and potential paths to peace (Crisis Group 2021), which is largely out of scope of this work. The conflict has detrimental effects on the human population of the region, in relation to massacres, gender-based violence, health (Gesesew et al. 2021) and food situation (Weldemichel 2021;Biadgilgn et al. 2022). About three out of four Tigrayans live from farming (Regional State of Tigray 2018) and the region typically depends on local yields. ...
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In this paper, Supervised Maximum Likelihood Classification (MLC) has been used for analysis of remotely sensed image. The Landsat ETM+ image has used for classification. MLC is based on Bayes' classification and in this classificationa pixelis assigned to a class according to its probability of belonging to a particular class. Mean vector and covariance metrics are the key component of MLC that can be retrieved from training data. Classification results have shown that MLC is the robust technique and there is very less chances of misclassification. The classification accuracy has been achieved overall accuracy of 93.75%, producer accuracy 94%, user accuracy 96.09% and overall kappa accuracy 90.52%.
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The Geba basin is one of the most water-stressed areas of Ethiopia, with only a short rainy period from mid-June to mid-September. Because rainfall in this region has been consistently erratic in the last decades, both in time and space, rain-fed agriculture has become problematic. Hence, in order to supplement rain-fed agriculture by irrigation, a detailed understanding of local and regional surface water and groundwater resources is important. The main objective of this study is to assess the available water resources in the Geba basin using a spatially distributed water balance model (WetSpass). Relevant input data for the model is prepared in the form of digital maps using remote sensing images, GIS tools, FAO and NASA databases, field reconnaissance and processing of meteorological and hydrological observations. The model produces digital maps of long-term average, seasonal and annual surface runoff, evapotranspiration and groundwater recharge. Results of the model show that 76% of the precipitation in the basin is lost through evapotranspiration, 18% becomes surface runoff and only 6% recharges the groundwater system. Model predictions are verified against river flow observations and are shown to be reliable. Additional maps are derived of accumulated surface runoff, safe yield for groundwater abstraction and water deficit for crop growth. Comparison of existing reservoirs with the accumulated runoff map shows that many reservoirs have failed because their design capacity is much higher than the actual inflow. Comparison of the safe yield map with the crop water deficit map shows that in most areas groundwater can be safely abstracted to supplement the water deficit for crop growth during the wet summer season. However, in the dry winter season the crop water deficit is too high to be supplemented by groundwater abstraction in a sustainable way.
Article
In the Northern Ethiopian Highlands, ca. 33% of the land is cropland, which is mainly cultivated by smallholders who based on indigenous knowledge plan their cropping system on the basis of spatio-temporal variability in rainfall. To understand the relationships between rainfall variability and cropping systems, a field campaign was undertaken in the rainy season of 2009 when 118 farmers were interviewed at different locations with different environmental characteristics. Five cropping systems were identified, each having a distinct cropping season length and crop association. Cropping systems with shorter cropping seasons were generally on the valleysides, whereas longer cycles occurred in the valley bottoms. The length of cropping season also increased from north–northeast to south–southwest. Crop associations within cropping systems also varied with altitude. Cropping systems changed in response to variation in annual rainfall. This resulted in shifts of cropping systems at catchment and regional scales, with cropping systems having longer cropping seasons where there was greater annual precipitation. The results were scaled up to the whole region by modelling the spatial distribution of cropping systems at a 8 × 8 km² resolution over the period 1996–2009. The results indicate that indigenous knowledge is important when assessing the impact of climatic variability on agricultural production and that large inter-annual variability in the duration of crop cover in Northern Ethiopia might be an important, although generally overlooked, explanatory factor for explaining previous land degradation cycles.
Book
Historical background, fundamental concepts, statistical considerations and a case study emphasize the need for absolute precision in applying remotely sensed data. This book is a complete guide to assessing the accuracy of maps generated from remotely sensed data.
Article
Summary This paper analyzes the inequality and determinants of flexibility in smallholder land access in post-war northern Mozambique. This paper demonstrates that high land endowments in aggregate do not imply equal access to cultivated or fallow land at the household level, even if land access has some flexibility across time. A formal test establishes the low extent of flexibility in land access at the household level in the study site. The econometric analysis further reveals that some groups of households such as female-headed households and those with low asset endowments or weak social institutions suffer from significant rigidities in land access.
Article
1Agriculture represents the dominant land use throughout much of western Europe, and a significant part of European biodiversity is associated with this habitat. We attempted to quantify the changes in agriculture and biodiversity in Britain since the 1940s.2There have been widespread declines in the populations of many groups of organisms associated with farmland in Britain and north-west Europe. The declines have been particularly marked amongst habitat specialists; many of the taxa still common on farmland are habitat generalists.3Farming practices have become increasingly intensive in the post-war period, with a dramatic reduction in landscape diversity. Since 1945, there has been a 65% decline in the number of farms, a 77% decline in farm labour and an almost fourfold increase in yield. Farms have become more specialized; the greatly increased use of machinery has made operations quicker and more efficient, but has resulted in the removal of 50% of the hedgerow stock. Autumn sowing of crops has become predominant, with winter stubbles now far less prevalent. The number and extent of chemical applications has increased greatly, but the net amount applied, and their persistence, has decreased in recent years.4Intensification has had a wide range of impacts on biodiversity, but data for many taxa are too scarce to permit a detailed assessment of the factors involved. Reduction in habitat diversity was important in the 1950s and 1960s; reduction in habitat quality is probably more important now.5As a case study, the declines in populations of seed-eating birds populations were assessed in relation to changing agricultural management. Generally, the declines were likely to be caused by a reduced food supply in the non-breeding season, although other factors may be important for particular species.6Agriculture will face a number of challenges in the medium term. While research into the mechanisms underlying species and habitat associations, and their interaction with scale, will be critical in under-pinning management, consideration of farmer attitudes and socio-economic factors is likely to be as important. Biodiversity may benefit from integrated farming techniques but these need to incorporate environmental objectives explicitly, rather than as a fringe benefit.
Article
Human land use is the main driver of terrestrial ecosystems change, and remote sensing is an important tool to monitor these changes. Landsat Thematic Mapper (TM) and Enhanced Thematic Mapper (ETM+) images have been the most important data source to map land cover change, but image artifacts often hinder or even prohibit digital change detection. This paper addresses a group of image distortions that display erroneous values in a single band while leaving the other bands of a spectrum undisturbed. Such artifacts may be due to different phenomena, for instance transmission and ground-processing problems or single event upsets. Automated artifact detection for those phenomena is often difficult, because erroneous band values often lie well within the range of naturally occurring radiance values. We developed IDL-based software that uses edge operators to detect and label affected pixels. Using a least-squares spectral-matching algorithm, the distorted spectrum is compared with undisturbed spectra in the local neighborhood and the undisturbed spectrum of best fit is determined. The erroneous band value is then replaced with the corresponding undisturbed value. This method was tested on seven Landsat TM images and on artificial data. Our results show that the distorted areas are precisely detected and that the correction procedure leads to meaningful spectra. This approach may be useful to minimize the effect of single-band distortions and allows for subsequent image analysis without the need to mask out distorted areas. The software tool includes a user interface and is available online.
Article
The use of the marasha ard plough for conservation agriculture in Northern Ethiopia Indigenous tillage systems are often undervalued in conservation agriculture (CA). In Ethiopia, since the 1970s there have been several attempts to develop and implement often major modifications to the marasha, the traditional ox-drawn ard plough, with the main aim of creating various types of surface depressions. The establishment of furrows and ridges increases soil moisture and grain yield and reduces soil loss. Dissemination of the modified tools, however, remains limited. Recent tendencies are towards testing relatively simple conservation agriculture tools. Major challenges remain, however; the need for capacity building and problems in marketing the tools. From experimental plots, often worked with exotic tools, there is a long road to real adoption by farmers. Rather than developing yet another CA tool, we investigate whether CA-based resource-conserving technologies might be achieved successfully with simple changes to the use of the marasha. On-farm observations on traditional conservation techniques were carried out throughout the northern Ethiopian highlands, and experiments were conducted involving resource-conserving technologies. Farmers traditionally use the marasha ard plough for various types of in situ soil and water conservation by creating surface depressions, either at the moment of sowing (terwah, derdero) or after crop emergence (shilshalo). Building upon this indigenous knowledge, we further developed resource-conserving technologies into a system named derdero+, whereby the traditional ard plough was found suitable for a “bed-and-furrow” system. From the socio-economic point of view, implementation of permanent beds and retention of stubble leads to decreased oxen (and straw) requirements, but also to an increased need for weeding in the first years. To overcome that problem, we introduced glyphosate herbicide into the tillage system. The decreased runoff (−51%) and soil loss (−81%) allow protection of the downslope areas from flooding, but soil nutrient build-up and soil structure improvement are slow processes, and hence the full benefit of the permanent bed system can only be expected after some years. Overall, this type of resource-conserving technology can be part of the ongoing intensification process which includes physical soil and water conservation, slope reforestation and irrigation development. It has, however, its own niche: the cropped land sensu stricto, i.e. the most important part of the land, both for the farmer and for a nation that is striving for long-term food security.
Article
This paper investigates strategies to improve land management, crop production and household income in the northern Ethiopian highlands based upon econometric analysis of household and plot level survey data collected from 500 households. We find that several profitable opportunities exist to improve land management, agricultural production and incomes.
Article
Developments in the field of image understanding in remote sensing over the past four decades are reviewed, with an emphasis, initially, on the contributions of David Landgrebe and his colleagues at the Laboratory for Applications of Remote Sensing, Purdue University. The differences in approach required for multispectral, hyperspectral and radar image data are emphasised, culminating with a commentary on methods commonly adopted for multisource image analysis. The treatment concludes by examining the requirements of an operational multisource thematic mapping process, in which it is suggested that the most practical approach is to analyze each data type separately, by techniques optimized to that data's characteristics, and then to fuse at the label level.
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Irrigation agriculture in the Raya graben (southern Tigray) in March
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