1-20 of 30 Results  for:

  • Keywords: irrigation x
Clear all


Soviet Collectivization in Central Asia  

Marianne Kamp

In Soviet Central Asia, efforts at the mass collectivization of agriculture began in early 1930, and by 1935, more than 80 percent of all farming and herding households joined collective farms (kolkhoz) or state farms (sovkhoz). The Communist Party’s main purpose was to control peasant lives and labor. Collectivization was supposed to lead to increased agricultural production due to modernized methods and intensification. The USSR’s Central Asian republics were given unachievable plans to raise their output of cotton, wheat, and meat, while wealthier herders and peasants were threatened with arrest and exile if they resisted collectivization. Collectivization was devastating for Kazakh nomadic herders, whose livestock numbers plummeted, and who endured a three-year long famine that killed more than one-fourth of the Kazakh population. Investments went into expanding irrigation canals and irrigable fields, forcing an ever-increasing number of kolkhoz members to expend most of their labor on cotton cultivation.


Water and Gender  

Martina Angela Caretta and Brandon Anthony Rothrock

Water relations are gendered, and there are various, differential socio-ecological and power dynamics that reify those relations at different spatial scales. There are multiple examples across the Global North and Global South that pinpoint the diverse productive and reproductive uses of water by men and women. Women, for instance, are more likely to be excluded from water management and decision making, while men are in control of water for agricultural production. Neoliberal framings of water in economic terms may exacerbate gender inequalities as neoliberal policies are often blind to the complex politics and power embedded in gender relations and water. Emerging literature on embodiment and emotions in waterscapes confronts neoliberal framings of water by theorizing the everyday lived experience of disenfranchised groups excluded from water management. Gendered studies of water relations focus largely on women, with limited attention to men. Male usage of water is often presented in relation to their role in water infrastructure management and design and water for leisure. As climate change becomes a more pressing issue in general society, existing uneven gendered relations of water resource use will be further exacerbated. With prevalent literature on gender relations focusing on women, future research needs to further incorporate studies of masculinity in gender relations to better inform adaptation and mitigation strategies. An understanding of gender and education would be insufficient without an understanding of both gender differentials in access to water and the gendered implications of climate change.


Environmental Benefits and Concerns of Center-Pivot Irrigation  

Leonor Rodriguez Sinobas

Center-pivot irrigation systems started in the United States in the mid-20th century as an irrigation method which surpassed the traditional surface irrigation methods. At that time, they had the potential to bring about higher irrigation efficiencies with less water consumption although their requirements in energy were higher too. Among their benefits, it is highlighted the feasibility to control water management as well as the application of agro-chemicals dissolved in the irrigation water and thus, center-pivot irrigation systems have spread worldwide. Nevertheless, since the last decade of the 20th century, they are facing actual concerns regarding ecosystem sustainability and water and energy efficiencies. Likewise, the 21st century has brought about the cutting edge issue “precision irrigation” which has made feasible the application of water, fertilizers, and chemicals as the plant demands taking into account variables such as: sprinkler´s pressure, terrain topography, soil variability, and climatic conditions. Likewise, it could be adopted to deal with the current key issues regarding the sustainability and efficiency of the center-pivot irrigation to maintain the agro-ecosystems but still, other issues such as the organic matter incorporation are far to be understood and they will need further studies.


The Yellow River, the Chinese State, and the Ecology of North China  

David A. Pietz

Flowing through the North China Plain, one of China’s major agricultural regions, the Yellow River has long represented a challenge to Chinese governments to manage. Preventing floods has been an overriding concern for these states in order to maintain a semblance of ecological equilibrium on the North China Plain. This region’s environment is heavily influenced by seasonal fluctuations in precipitation, leading to a long history of famine, particularly in the late 19th and early 20th centuries when water management structures disintegrated with the deterioration of the imperial system. In the 20th century, new civil and hydraulic engineering techniques and technologies held the promise for enhanced management of the region’s waterways. After 1949, the new government of the People’s Republic used a hybrid approach consisting of the tenets of multipurpose water management combined with the tools of mass mobilization that were hallmarks of the Chinese Communist Party. The wide-ranging exploitation of surface and groundwater resources during the Maoist period left a long shadow for the post-Mao period that witnessed rapid consumption of water to fuel agricultural, industrial, and urban reforms. The challenge for the contemporary state in China is creating a system of water allocation through increased supply and demand management that can sustain the economic and social transformations of the era.


The Indus River  

David Gilmartin

The Indus is the westernmost of the great arc of rivers across southern and eastern Asia flowing from the Tibetan plateau, and its watershed today includes parts of China, Afghanistan, Pakistan, and India. Flowing through a predominantly arid region, it was the site of South Asia’s earliest urban civilization in the 3rd millennium bce. Today, it features some of the most highly developed irrigation works in the world, supporting large agricultural populations on the plains of Pakistan and in northwestern India. Its history has been defined not only by the dynamics of the Indus river system, with its highly seasonal, monsoon-fed flows descending from the mountains, but also by its critical role in defining a transitional zone of migration and mobility situated between central Asia and the Iranian plateau, on the one hand, and the wetter parts of the Indian subcontinent, on the other. Within this context, it played a critical role in the coming of Islam to the subcontinent from the west. Since the late 19th century it has been the site of one of the modern world’s most dramatic irrigation-based transformations, rooted in British colonial canal-building and the opening of large canal colonies for agricultural settlement. What was already the world’s largest, integrated irrigation system was divided between India and Pakistan in 1947 (with the larger part going to Pakistan). The subsequent Indus Waters Treaty of 1960, which was intended to facilitate the continuing management of the river basin, accomplished this only through the intensification of irrigation investment and the maximization of the available water’s “use,” with all the difficult environmental and political challenges that has brought.


Water User Associations and Collective Action in Irrigation and Drainage  

Bryan Bruns

If there is too little or too much water, farmers may be able to work together to control water and grow more food. Even before the rise of cities and states, people living in ancient settlements cooperated to create better growing conditions for useful plants and animals by diverting, retaining, or draining water. Local collective action by farmers continued to play a major role in managing water for agriculture, including in later times and places when rulers sometimes also organized construction of dams, dikes, and canals. Comparative research on long-lasting irrigation communities and local governance of natural resources has found immense diversity in management rules tailored to the variety of local conditions. Within this diversity, Elinor Ostrom identified shared principles of institutional design: clear social and physical boundaries; fit between rules and local conditions, including proportionality in sharing costs and benefits; user participation in modifying rules; monitoring by users or those accountable to them; graduated sanctions to enforce rules; low-cost conflict resolution; government tolerance or support for self-governance; and nested organizations. During the 19th and 20th centuries, centralized bureaucracies constructed many large irrigation schemes. Farmers were typically expected to handle local operation and maintenance and comply with centralized management. Postcolonial international development finance for irrigation and drainage systems usually flowed through national bureaucracies, strengthening top-down control of infrastructure and water management. Pilot projects in the 1970s in the Philippines and Sri Lanka inspired internationally funded efforts to promote participatory irrigation management in many countries. More ambitious reforms for transfer of irrigation management to water user associations (WUAs) drew on examples in Colombia, Mexico, Turkey, and elsewhere. These reforms have shown the feasibility in some cases of changing policies and practices to involve irrigators more closely in decisions about design, construction, and some aspects of operation and maintenance, including cooperation in scheme-level co-management. However, WUAs and associated institutional reforms are clearly not panaceas and have diverse results depending on context and on contingencies of implementation. Areas of mixed or limited impact and for potential improvement include performance in delivering water; maintaining infrastructure; mobilizing local resources; sustaining organizations after project interventions; and enhancing social inclusion and equity in terms of multiple uses of water, gender, age, ethnicity, poverty, land tenure, and other social differences. Cooperation in managing water for agriculture can contribute to coping with present and future challenges, including growing more food to meet rising demand; competition for water between agriculture, industry, cities, and the environment; increasing drought, flood, and temperatures due to climate change; social and economic shifts in rural areas, including outmigration and diversification of livelihoods; and the pursuit of environmental sustainability.


Surface Irrigation  

Luis S. Pereira and José M. Gonçalves

Surface irrigation is the oldest and most widely used irrigation method, more than 83% of the world’s irrigated area. It comprises traditional systems, developed over millennia, and modern systems with mechanized and often automated water application and adopting precise land-leveling. It adapts well to non-sloping conditions, low to medium soil infiltration characteristics, most crops, and crop mechanization as well as environmental conditions. Modern methods provide for water and energy saving, control of environmental impacts, labor saving, and cropping economic success, thus for competing with pressurized irrigation methods. Surface irrigation refers to a variety of gravity application of the irrigation water, which infiltrates into the soil while flowing over the field surface. The ways and timings of how water flows over the field and infiltrates the soil determine the irrigation phases—advance, maintenance or ponding, depletion, and recession—which vary with the irrigation method, namely paddy basin, leveled basin, border and furrow irrigation, generally used for field crops, and wild flooding and water spreading from contour ditches, used for pasture lands. System performance is commonly assessed using the distribution uniformity indicator, while management performance is assessed with the application efficiency or the beneficial water use fraction. The factors influencing system performance are multiple and interacting—inflow rate, field length and shape, soil hydraulics roughness, field slope, soil infiltration rate, and cutoff time—while management performance, in addition to these factors, depends upon the soil water deficit at time of irrigation, thus on the way farmers are able to manage irrigation. The process of surface irrigation is complex to describe because it combines surface flow with infiltration into the soil profile. Numerous mathematical computer models have therefore been developed for its simulation, aimed at both design adopting a target performance and field evaluation of actual performance. The use of models in design allows taking into consideration the factors referred to before and, when adopting any type of decision support system or multicriteria analysis, also taking into consideration economic and environmental constraints and issues. There are various aspects favoring and limiting the adoption of surface irrigation. Favorable aspects include the simplicity of its adoption at farm in flat lands with low infiltration rates, namely when water conveyance and distribution are performed with canal and/or low-pressure pipe systems, low capital investment, and low energy consumption. Most significant limitations include high soil infiltration and high variability of infiltration throughout the field, land leveling requirements, need for control of a constant inflow rate, difficulties in matching irrigation time duration with soil water deficit at time of irrigation, and difficult access to equipment for mechanized and automated water application and distribution. The modernization of surface irrigation systems and design models, as well as models and tools usable to support surface irrigation management, have significantly impacted water use and productivity, and thus competitiveness of surface irrigation.


Water Management in East Africa  

Matthew V. Bender

East Africa is among the most environmentally diverse regions of the continent, and this diversity is reflected in its hydrology. The steppe plains, home to much of the region’s great wildlife, are defined by scarcity of rainfall and surface water resources. Within this sea of aridity, mountain peaks such as Kilimanjaro, Kenya, and Meru induce large amounts of rainfall and give rise to rivers that reach out into the grasslands. To the west, the forest–savannah mosaic and the shorelines of the Great Lakes likewise feature plentiful precipitation and surface water, giving rise to abundant vegetation and marine life. The Indian Ocean coast falls between in terms of rain, but its fate has been shaped by oceanic trade. In short, East Africa is a hydrological mosaic that has long influenced the social, cultural, and economic diversity of its human populations. The peoples of East Africa have long depended on the region’s water resources for their livelihoods. They have made sense of the region’s waterscapes, and developed strategies to manage them, in ways that reflected their own needs. Water management consisted not just of hydrological and technological expertise, but also cultural, spiritual, and political expertise. These in turn shaped economic as well as social relationships and hierarchies. With the onset of European colonization in the 19th and 20th centuries, water management became a focal point of struggles between local communities and various colonial actors—government officers, scientists, missionaries, and settlers—who developed very different impressions of the region’s waterscapes. These struggles involved not only conflict over the physical control of water resources, but also debates over what constituted useful and relevant water-management knowledge. Colonial actors described their water management in terms of science and modernity, while existing knowledge and practice were framed as primitive, wasteful, and destructive. Over the 20th century, conflicts intensified as users, African as well as European, demanded larger shares of increasingly scarce water resources. The post-colonial period did not spell an end to these struggles. Since the late 20th century, water management has emerged as a key aspect of national strategies for economic and social development. Yet decades of emphasis and millions of dollars spent have not led to sufficient progress in providing water to everyday people. Today, millions of East Africans lack access to clean, reliable water, a problem that is likely to worsen in the future.


Indigenous Polynesian Agriculture in Hawaiʻi  

Noa Kekuewa Lincoln and Peter Vitousek

Agriculture in Hawaiʻi was developed in response to the high spatial heterogeneity of climate and landscape of the archipelago, resulting in a broad range of agricultural strategies. Over time, highly intensive irrigated and rainfed systems emerged, supplemented by extensive use of more marginal lands that supported considerable populations. Due to the late colonization of the islands, the pathways of development are fairly well reconstructed in Hawaiʻi. The earliest agricultural developments took advantage of highly fertile areas with abundant freshwater, utilizing relatively simple techniques such as gardening and shifting cultivation. Over time, investments into land-based infrastructure led to the emergence of irrigated pondfield agriculture found elsewhere in Polynesia. This agricultural form was confined by climatic and geomorphological parameters, and typically occurred in wetter, older landscapes that had developed deep river valleys and alluvial plains. Once initiated, these wetland systems saw regular, continuous development and redevelopment. As populations expanded into areas unable to support irrigated agriculture, highly diverse rainfed agricultural systems emerged that were adapted to local environmental and climatic variables. Development of simple infrastructure over vast areas created intensive rainfed agricultural systems that were unique in Polynesia. Intensification of rainfed agriculture was confined to areas of naturally occurring soil fertility that typically occurred in drier and younger landscapes in the southern end of the archipelago. Both irrigated and rainfed agricultural areas applied supplementary agricultural strategies in surrounding areas such as agroforestry, home gardens, and built soils. Differences in yield, labor, surplus, and resilience of agricultural forms helped shape differentiated political economies, hierarchies, and motivations that played a key role in the development of sociopolitical complexity in the islands.


Transboundary Water Governance and Small Basin Councils in Central Asia  

Stefanos Xenarios, Murat Yakubov, Aziza Baubekova, Olzhas Alshagirov, Zhassulan Zhalgas, and Eduardo Jr Araral

Central Asia (CA) hosts some of the world’s most complex and most extensive water management infrastructures allocated in the two major transboundary basins of the Amudarya and Syrdarya Rivers. The upstream countries of Tajikistan and Kyrgyzstan mainly utilize the rivers for hydropower and irrigation, whereas the downstream countries of Uzbekistan, Turkmenistan, and Kazakhstan primarily use them for irrigation purposes. The governance of the two river basins has been contested since Soviet times, and more so after the independence of the CA countries. The scheme of Small Basin Councils (SBCs) has been introduced in the region from 2010 to 2022 to improve local and transboundary water governance at a sub-basin and catchment level. Implementing SBCs in CA is still in the experimental phase, and its contribution to river basin management is insufficiently explored. However, there are indications that SBCs play a significant role in raising awareness of and engagement with local communities and improving local and transboundary governance management and coordination. Most important, SBCs can help resolve critical issues in agricultural water allocation, one of the most contentious issues for transboundary water governance in CA. The basin councils could become significant leverage for improving water governance on national and transboundary systems in CA by actively engaging local communities in management, planning, and administration.


Environmental Approaches to Soviet Central Asia  

Sarah Cameron

The vast region known as “Soviet Central Asia” encompassed the territory of five Soviet republics, Kazakhstan, Kirgizia, Uzbekistan, Tajikistan, and Turkmenistan. Because of the region’s environmental features, particularly its aridity, historically there had been a close linkage between people and the environment in this region. But the Soviet regime set out to radically reshape this relationship, focusing on the fields of agriculture and animal husbandry, large-scale water engineering, nuclear and biological weapons testing, and medicine and public health. By focusing on the environmental impact of these policies, scholars can see how Moscow’s efforts brought many benefits to the region. Cotton production boomed, and Moscow declared the eradication of malaria. But they also left horrific scars. Josef Stalin’s program of agricultural collectivization devastated Kazakhstan, resulting in the death of more than 1.5 million people. The Aral Sea, once one of the world’s largest bodies of water, began to shrink dramatically during the Soviet era, a development due in large part to Moscow’s efforts to divert the waters that fed the sea to cotton production.


The Yangzi River and the Environmental History of South China  

Ian Matthew Miller

Over the last seven thousand years, humans have gradually domesticated the environment of South China. Transitioning from a reliance on wild environments, humans tamed plants and animals and transformed the landscapes and waterscapes to better fit their needs. Rice paddies, orchards, and artificial ponds and forests replaced naturally seeded woodlands and seasonal wetlands. Even the Yangzi River, and many of the other rivers, lakes, and seashores, were transformed by polders, dikes, and seawalls to better support human activities, especially rice agriculture. In the last thousand years, farmers intensified their control of the cultivated landscape through terracing, irrigation, flood prevention, and new crop rotations. They planted commercial crops like cotton, fruits, oilseeds, tea, and sugar cane in growing concentrations. Migrants and merchants spread logging, mining, and intensive agriculture to thinly settled parts of the south and west. Since the 17th century, New World crops like sweet potatoes, chilis, maize, and tobacco enabled a further intensification of land use, especially in the mountains. Since the early 1800s, land clearance and river diking reached extremes and precipitated catastrophic flooding, social unrest, and a century of warfare. Since 1950, the People’s Republic has overseen three further waves of degradation accompanying the mass campaigns of the Mao era and the market reforms under Deng Xiaoping. Following catastrophic flooding in 1998, the government has increasingly worked to reverse these trends. Nonetheless, South China remains one of the most intensively cultivated environments in the world and continues to feel the effects of new attempts to tame and expropriate the forces of nature.


Colonial Agricultural Development Schemes  

Monica van Beusekom

The period from the 1920s to the end of colonial rule saw increasing government intervention in agricultural production and the adoption of ambitious agricultural development schemes. These development schemes often aimed to increase and control the production and marketing of cash crops such as cotton and peanuts, essential to European industries. Examples include the Gezira Scheme (Sudan), the Office du Niger (French Soudan), the Tanganyika Groundnut Scheme, the Compagnie Générale des Oléagineux Tropicaux (CGOT, Senegal), as well as a host of other schemes. Confident in their agricultural expertise, colonial planners often sought radical transformations in African agricultural systems, away from extensive hoe cultivation toward intensive plow agriculture following a strict crop rotation. Worries about environmental degradation and population growth, as well as the need to manage social dislocation and maintain political stability, framed colonial strategies. Encountering African farmers with priorities and practices that were often at odds with their own, colonial planners failed to transform agriculture in the ways they intended. Nonetheless, development still wrought significant change as farmers considered whether to circumvent, resist, adapt, or adopt new technologies and farming methods. If at first agricultural development schemes were localized and mostly ineffective efforts to make empire profitable, by the 1940s and 1950s, agricultural development interventions became more widespread and intrusive. This helped generate rural support for anticolonial movements. Nonetheless, by the last decades of colonial rule, the idea of planned development as desirable became commonplace, not just within colonial governments, but also in international institutions and among nationalist leaders. Thus, state-led agricultural development would remain a powerful force in independent Africa.


Emerging Issues in Groundwater Sustainability: New Challenges  

Encarna Esteban

The increased pressure on groundwater has resulted in a major deterioration of the overall status of this resource. Despite efforts to control the degradation of underground water bodies, most aquifers worldwide experience serious quality and quantity problems. New emerging issues around groundwater resources have become relevant and pose additional protection and management challenges. Climate change, with predictable impacts on temperature and precipitation, will cause considerable fluctuations in aquifer recharge levels and subsequent problems in the status of these water bodies. Expected reductions in water availability will increase groundwater withdrawals not just for irrigation but also for urban and industrial water use. Declines in stored water will have an impact on many freshwater ecosystems whose survival depends on the status of groundwater bodies. Furthermore, land subsidence, as a side effect of aquifer overexploitation, involves land collapse and deformation that are especially harmful for urban areas and deteriorate physical and hydrological water systems. All these new challenges require integrated planning strategies and multisectorial solutions to curtail the deterioration of these resources. Although these issues have been studied, in-depth analyses of the economic, social, and policy implications of groundwater management strategies are still necessary.


Agricultural Practices and Environmental Impacts of Aztec and Pre-Aztec Central Mexico  

Deborah L. Nichols

The Basin of Mexico is a key world region for understanding agricultural intensification and the development of ancient and historic cities and states. Archaeologists working in the region have had a long-standing interest in understanding the dynamics of interactions between society and environment and their research has been at the forefront of advances in both method and theory. The Basin of Mexico was the geopolitical core of the Aztec empire, the largest state in the history of Mesoamerica. Its growth was sustained by a complex economy that has been the subject of much research. Two themes underlie a broad interest in the pre-Hispanic agriculture of the Basin of Mexico. First, how with a Neolithic technology did the Aztecs and their predecessors sustain the growth of large cites, dense rural populations, and the largest state system in the history of pre-Hispanic Mesoamerica? Second, what is the relationship of agricultural intensification and urbanization and state formation? Mesoamerica is the only world region where primary civilizations developed that lacked domestic herbivores for either food or transportation. Their farming depended entirely on human labor and hand tools but sustained large cities, dense populations, and complex social institutions. Intensive agriculture began early and was promoted by risk, ecological diversity, and social differentiation, and included irrigation, terracing, and drained fields (chinampas). Most farming was managed by smallholder households and local communities, which encouraged corporate forms of governance and collective action. Environmental impacts included erosion and deposition, but were limited compared with the degradation that took place in the colonial period.


Environmental Footprints of Modernization Trends in Rice Production Systems of Southeast Asia  

Reiner Wassmann

Assessing the environmental footprints of modern agriculture requires a balanced approach that sets the obviously negative effects (e.g., incidents with excessive use of inputs) against benefits stemming from increased resource use efficiencies. In the case of rice production, the regular flooding of fields comprises a distinctive feature, as compared to other crops, which directly or indirectly affects diverse impacts on the environment. In the regional context of Southeast Asia, rice production is characterized by dynamic changes in terms of crop management practices, so that environmental footprints can only be assessed from time-dependent developments rather than from a static view. The key for the Green Revolution in rice was the introduction of high-yielding varieties in combination with a sufficient water and nutrient supply as well as pest management. More recently, mechanization has evolved as a major trend in modern rice production. Mechanization has diverse environmental impacts and may also be instrumental in tackling the most drastic pollution source from rice production, namely, open field burning of straw. As modernization of rice production is imperative for future food supplies, there is scope for developing sustainable and high-yielding rice production systems by capitalizing on the positive aspects of modernization from a local to a global scale.


Virtual Water  

Francesca Greco, Martin Keulertz, and David Dent

Virtual water is the water contained in food, understood not only as the physical amount within the product but also as the amount of water required to generate it over time, from planting to final harvest. Despite Tony Allan defined virtual water in the context of the water needed to produce agricultural commodities, the concept has been subsequently expanded to include the water needed to produce non-agricultural commodities and industrial goods by Arjen Hoekstra, the creator of the water footprint indicator. Virtual water is a revolutionary concept because it describes something never conceptualized before: the water “embedded” in a product. Allan used virtual water “food water” and “embedded water” as interchangeable terms. Virtual water “trade” is the result of food trade: where agricultural goods are traded across countries, the water needed to produce that product in country A is, in fact, consumed in country B. Country B is therefore not consuming its own local resources when consuming imported food. Allan believed that this mechanism could alleviate irrigation water needs in water-scarce areas when food imports are in place. The virtual water content of a product (measured in liters per kilo) is provided not only by the sum of the irrigation water that has been withdrawn from surface and underground sources in order to grow crops—called “blue water.” Virtual water is also composed of the rainwater consumed by plants and persisting in agricultural soil moisture, which does not percolate down to the aquifers or go back to rivers and lakes. This second component is called “green water.” The green- and blue-water components form the total amount of water embedded in crops, and they are the two components of virtual water. Allan borrowed the concepts of green and blue water from the work of Malin Falkenmark. Virtual water and virtual water “trade” have been largely explored and studied at both local and global levels, becoming the subjects of thousands of papers between 1993 and 2022, which helped uncover global appropriation of a local resource that is unevenly distributed by nature and very often unequally “traded” by humans: water.


Classification and Mitigation of Soil Salinization  

Tibor Tóth

Soil salinity has been causing problems for agriculturists for millennia, primarily in irrigated lands. The importance of salinity issues is increasing, since large areas are affected by irrigation-induced salt accumulation. A wide knowledge base has been collected to better understand the major processes of salt accumulation and choose the right method of mitigation. There are two major types of soil salinity that are distinguished because of different properties and mitigation requirements. The first is caused mostly by the large salt concentration and is called saline soil, typically corresponding to Solonchak soils. The second is caused mainly by the dominance of sodium in the soil solution or on the soil exchange complex. This latter type is called “sodic” soil, corresponding to Solonetz soils. Saline soils have homogeneous soil profiles with relatively good soil structure, and their appropriate mitigation measure is leaching. Naturally sodic soils have markedly different horizons and unfavorable physical properties, such as low permeability, swelling, plasticity when wet, and hardness when dry, and their limitation for agriculture is mitigated typically by applying gypsum. Salinity and sodicity need to be chemically quantified before deciding on the proper management strategy. The most complex management and mitigation of salinized irrigated lands involves modern engineering including calculations of irrigation water rates and reclamation materials, provisions for drainage, and drainage disposal. Mapping-oriented soil classification was developed for naturally saline and sodic soils and inherited the first soil categories introduced more than a century ago, such as Solonchak and Solonetz in most of the total of 24 soil classification systems used currently. USDA Soil Taxonomy is one exception, which uses names composed of formative elements.


Saharan Peoples and Societies  

E. Ann McDougall

The Sahara: bridge or barrier? Today, most would answer that the desert was more a historical facilitator than hindrance in moving commodities, ideas, and people between North and sub-Saharan Africa. A recent publication even coined a new name for the region: “trans-Saharan Africa.” However, the Sahara is also a place where people live. Complex societies, sophisticated polities, extensive economies—all flourished at various times, waxing and waning in response to much the same factors as societies elsewhere. It is just that in the Sahara the vagaries of climate and the availability of water always established the parameters of development. A long-term drying era led to the dispersal of the Late Stone Age Dhar-Tichitt agro-pastoral settlements in eastern Mauritania, but in the east, Lake “Mega-Chad” shrank, leaving rich, sandy soils that attracted new cultivators. The Garamantes people of the Libyan Fezzan overcame their lack of water by developing a sophisticated underground irrigation system that supported an urbanized, cosmopolitan civilization that outlasted the Roman Empire. The introduction of the camel in the 4th century and the gradual growth of Islam from at least the 9th century added new possibilities for economic, cultural, and religious life. The Sahara benefited from the sequence of medieval empires emerging across its southern desert edge. Camel pastoralism, salt mining, oasis agriculture, and expansive trade networks shaped the region’s economy; those same networks facilitated cultural and scholarly exchanges. As Islam took root, growing its own understandings of North African and Middle Eastern schools of thought, a prodigious body of Saharan scholarship was created. It underpinned much of the jihad-led political upheaval and state-building in the 18th and 19th Sahel. Saharan clerics also directed their religious fervor against the invasion of French imperialists; “pacification” took the colonialists decades to achieve. But the impact of this violence exacerbated traditional clan conflict and disrupted economic life. So too did policies aimed at sedentarizing pastoralists and reshaping their social relations in the interests of the colonial economy. Much talked-about but largely ineffective efforts to abolish slavery had far less real impact than taxation policies; these both suppressed traditional exactions such as those levied by “warriors” and introduced new ones, including those to be paid in forced labor. Life in the Sahara became increasingly untenable. The arrival of Independence did nothing to address colonial legacies; the years of drought that devastated herds and crops in the desert and along its edge less than a decade later further fueled both political instability and economic crisis. That today the region nurtures radicalized Islamic movements promising to return “true meaning” (not to mention material benefits) to that life is not surprising.


Groundwater Development Paths in the U.S. High Plains  

Renata Rimšaitė and Nicholas Brozović

The High Plains Aquifer is the largest aquifer in the United States and the major source of groundwater withdrawals in the region. Although regionally abundant, groundwater availability for agriculture and other uses is not uniform across the area. Three separate states comprising the most significant portion of the aquifer have distinct climate and hydrologic characteristics, water law systems, and institutional groundwater governance leading to different concerns about water policy issues across the area. The northern, largest, and most saturated part of the High Plains Aquifer is located under Nebraska. The state has the largest irrigated area in the United States, most of which is groundwater irrigated. Nebraska is the home of the largest companies in the center pivot irrigation industry. Center pivot technology has had a fundamental role in expanding groundwater-fed irrigation. Nebraska is not free from groundwater depletion issues, but these issues are more important in central and south-central parts of the aquifer underlying large, primarily agricultural, lands of Kansas and Texas. The natural aquifer recharge is much lower in the south-central parts of the region, which has caused large groundwater extractions to have more significant water declines than in Nebraska. In the United States, the greatest portion of water quantity management regulatory oversight is left to individual states and local government agencies. Each of the three states has a unique legal system, which highly influences the framework of groundwater management locally. In Nebraska, groundwater is governed following two doctrines: correlative and reasonable use, which, in times of water shortage, lead to a proportional reduction of everyone’s allocation. Kansas uses the prior appropriation doctrine to manage groundwater, which applies the seniority principle when there is scarcity in water availability, making junior water rights holders bear the greatest risk. The absolute ownership doctrine is used to govern groundwater in Texas, which allows landowners to drill wells on their property and extract as much water as needed. Institutional groundwater governance in Nebraska is performed by the system of 23 locally elected Natural Resources Districts having full regulatory power to manage the state’s groundwater. The local governments use a variety of regulatory and incentive-based groundwater management tools to achieve local groundwater management goals. In Kansas, the Chief Engineer in the Kansas Department of Agriculture is in charge of water administration for the state. The Kansas legislature established five Groundwater Management Districts to address groundwater depletion issues, which can make policy recommendations but do not have the power to regulate. Groundwater Conservation Districts were created in Texas to provide protection from uncontrolled water mining in the state. The districts gained more power to regulate and enforce rules over time; however, significant groundwater depletion issues remain. Multiple lessons have been learned across the region since the beginning of groundwater development. Some of these could be applied in other areas seeking to address negative consequences of groundwater use. Forward-looking perspectives about groundwater management in the region vary from strong government-led solutions in Nebraska to various producer-initiated innovative approaches in Kansas and Texas.