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33-760: The Bahr Salamat is a seasonally intermittent river in Chad . It flows southwards, and is a tributary of the Chari River . When the Bahr Salama river is flowing, it runs through the community of Am Timan and also the Bahr Salamat Faunal Reserve of Chad. The Chari River is a tributary of Lake Chad . This article related to a river in Chad is a stub . You can help Misplaced Pages by expanding it . Intermittent river According to

66-559: A 70-year period, identifying overgrazing, global changes, and the ecological effects of megafauna extinction as key factors. Their findings shed light on the multifaceted drivers behind changes in savannah ecosystems. Echoing this theme of alternative strategies to combat overgrazing, Kriegisch et al. (2019) demonstrated how drift- kelp availability could reduce the foraging movement of overgrazing sea urchins, suggesting that alternative food sources may significantly influence grazing behaviors and aid in managing marine ecosystem pressures. In

99-571: A defined channel, and rely mainly on storm runoff, as their aquatic bed is above the water table . An ephemeral stream does not have the biological, hydrological, and physical characteristics of a continuous or intermittent stream. Opinions on the Clean Water Act (CWA) from the Supreme Court have classified intermittent streams as non-jurisdictional and thus outside of legal protection. Prior to 2001, virtually all bodies of water in

132-616: A food source for a variety of terrestrial animals, such as birds, mammals, and reptiles. Different types of fishes inhabit intermittent rivers. The Brassy minnow ( Hybognathus hankinsoni ) is native to the intermittent Niobrara River, Wyoming. Redband trout ( Oncorhynchus mykiss gairdneri ) is native to intermittent desert streams of southwestern Idaho. The West Fork Smith River provides vital habitat to different species, including coho salmon, returning to spawn in Oregon. Cobitis shikokuensis (Hina-ishi-dojo) in intermittent rivers move into

165-415: A high proportion of regional biodiversity. The riparian zone of intermittent rivers can provide habitat and resources for a variety of organisms, and may also be an important source of nutrients for habitats downstream. The dry period of intermittent streams is ended by what is called "rewetting" or a wetting front. Rewetting is defined as the resumption of waterflow through the stream. This happens when

198-470: A similar vein, the research by Cai et al. (2020) presents a stark example of the terrestrial impact of overgrazing, showing how the fertile island effect collapses under extreme conditions in shrub-encroached grasslands . This case study emphasizes the critical need for sustainable grazing practices to protect soil health and maintain ecosystem functionality, further illustrating the wide-reaching consequences of overgrazing across diverse habitats. Overgrazing

231-495: Is a direct consequence of the extensive networks of dams and aqueducts that were built for human withdrawal of water that used to flow into wetlands, deltas, and inland sinks. This phenomenon can be observed in the Colorado River, whose flow has decreased significantly since 1905. In recent years, several U.S. states and Mexico have used significant amounts of water for agricultural and urban uses, which caused flows reaching

264-458: Is a massive threat to the native species of flora and fauna, especially the native bushes which are often overlooked by invasive species looking for homes. Mustalids, rabbits, hares and possums often eat the plants that hold soil together. This makes the ground very unstable and crumbly. If soil is unstable, it is prone to collapse in extreme weather events such as floods and heavy rain. This is detrimental to farmers of crops and animals alike. 40% of

297-507: Is considered the main cause of woody plant encroachment at the expenses of grasses on a land area of up to 45 million hectares. In many arid zones in Australia , overgrazing by sheep and cattle during the 19th century, as pastoralism was introduced by European settlers, caused many long-lived species of trees and shrubs to give way to short-lived annual plants and weed species. Introduced feral rabbits , cats and foxes exacerbated

330-645: Is used as an example in the economic concept now known as the Tragedy of the Commons devised in a 1968 paper by Garrett Hardin . This cited the work of a Victorian economist who used as an example the over-grazing of common land. Hardin's example could only apply to unregulated use of land regarded as a common resource. Normally, rights of use of common land in England and Wales were, and still are, closely regulated, and available only to "commoners". If excessive use

363-591: The American bison of the Great Plains , or migratory wildebeest of the African savannas , or by holistic planned grazing. Overgrazing typically increases soil erosion . With continued overutilization of land for grazing, there is an increase in degradation. This leads to poor soil conditions that only xeric and early successional species can tolerate. A meta-analysis of 148 studies found that

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396-453: The U.S. Environmental Protection Agency definition, an intermittent river, or intermittent stream, is any river or stream that only flows during certain times of the year, and may not have any flowing surface water during the dry season. Intermittent rivers do not rely on, but may be supplemented, by stormwaters or other runoff from upstream sources. Their channels are well-defined, as compared to ephemeral streams, which may or may not have

429-668: The American Southwest during precipitation events. Many incised arroyos that are destructive to stream beds and adjacent man-made structures were formed as a result of drainage channelization and overgrazing during the late nineteenth century along with the influx of American settlers in the Southwestern United States. Glacial streams are considered intermittent streams as the flow intermittence fluctuates with solar energy input. Most glacial streams are alpine headwater streams that receive water from

462-546: The Colorado River delta to drop to near zero. Effects of climate change such as higher air temperatures are predicted to accelerate drying and cause more intermittency in rivers. Intermittent rivers are found on every continent, and may even be more common than perennial rivers. More than 30% of the total length and discharge of the global river network is estimated to be intermittent rivers. However, due to some low-order streams being difficult to categorize or track, this total could be over 50% when taking those into account. In

495-575: The Mongolian steppes, Liu et al. (2013) found that approximately 60% of vegetation decline could be attributed to climate factors, with the rest significantly influenced by increased goat density due to overgrazing. This points to a complex interplay between climate change and grazing practices in ecosystem degradation. Further expanding our understanding, Stevens et al. (2016) investigated woody encroachment in South African savannahs over

528-571: The United States were considered jurisdictional because of their potential to function as a habitat for migratory birds. Following this 2001 Supreme Court ruling on US waters, Solid Waste Agency of Northern Cook County vs. US Army Corps of Engineers , the court went on to see two cases in 2006 further involving this matter. Rapanos vs. United States and Carabell vs. United States , after being combined into one decision, added new analytical thresholds to be met for protection but ultimately left

561-405: The biodiversity. Turning to the aquatic environment, Ling et al. (2015) have documented the phenomenon of catastrophic sea urchin overgrazing and its role in marine ecosystem regime shifts. Their study underscores the urgent need for effective management and conservation strategies to mitigate the profound ecological impacts of overgrazing, highlighting the issue's global scope. Similarly, on

594-502: The determination of what were to be protected U.S. waters up to the EPA, the U.S. Army Corps of Engineers, and further court cases. Recent litigation was brought by eighteen states' attorneys general because of a change to the interpretation of what is to be considered by the EPA and Army Corps of Engineers as "waters of the United States" during May 2020. Intermittent streams contain water during periods when groundwater levels are above or at

627-581: The ecology of intermittent rivers. Disturbances caused by humans can result in short-term (pulse) and long-term (press) effects on intermittent stream habitats. Overgrazing Overgrazing occurs when plants are exposed to intensive grazing for extended periods of time, or without sufficient recovery periods. It can be caused by either livestock in poorly managed agricultural applications, game reserves , or nature reserves . It can also be caused by immobile, travel restricted populations of native or non-native wild animals . Overgrazing reduces

660-423: The face of global climate change, this total is further increasing, as many of the world's rivers that were once perennial are now intermittent in regions suffering from severe climatic drying or water appropriation. Intermittent streams can be found in many different climate regions. For example, arroyos are intermittent streams that erode deep vertical channels through fine sediment in arid and semiarid regions in

693-428: The flowing, contraction/fragmentation, and dry phases. Intermittent streams tend to have a food web based heavily on detritus and follow the bottom-up trophic model. Both the ratios of predator to prey and the number of trophic levels depend on the size of the intermittent stream. Intermittent rivers face many threats. Diversion of river water for large-scale consumption, such as industrial use or for farming, can alter

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726-598: The gain of the water is higher than the loss of it into the pores of the substrate/soil, also known as infiltration. Rewetting causes changes both in the dissolved nutrients in the stream, and in species compositions. During dry periods of intermittent rivers, terrestrial animals can gain access to resources and areas that were otherwise inaccessible, either due to natural or man-made obstructions. Additionally, when drying, these riverbeds often leave behind organisms, such as fish, which were unable to relocate in response to lowering water levels. These organisms are often used as

759-417: The glacial meltwater. The streams become dry or freeze starting from autumn and last until early spring; the flow of the glacial streams is highest during summer. The intermittency of the glacial streams also fluctuates at different times of the day. The inhabitants of intermittent rivers can change with the water level. As a result of contrasting conditions throughout the year, invertebrate assemblages of

792-441: The hyporheic zone when water flows are low. When the water returns, C. shikokuensis emerge out of the hyporheic zone to recolonize the flowing river system. During stream drying, Campostoma spadiceum ( Highland stoneroller ) move into pool habitats when riffle areas become too shallow for survival. The food web of intermittent streams differs from perennial streams in that species number and abundance change drastically among

825-421: The level of stream's channel, allowing for surface flow. The mechanisms which control surface flow of intermittent streams are climatically and geographically specific. For example, intermittent streams fed by snowmelt and glacial meltwater cease to flow when they either freeze or there is not enough inputs to sustain surface water. Streams in more arid regions stop flowing due to the depletion of water storage in

858-503: The same intermittent stream can be notably distinct from one another. How biodiversity of these habitats changes with conditions has been debated in literature. Current findings suggest that while lotic biodiversity generally decreases with increasing flow intermittence, increased lentic and terrestrial biodiversity during those periods can compensate. Thus, when lotic (flowing water), lentic (lake), and terrestrial communities are considered together, intermittent rivers can account for

891-571: The surrounding aquifer and channel banks. The diversion of water and impoundment for human use, such as for flood control and irrigation storage, have caused intermittency in many rivers that used to be perennial. This was the case for several large rivers such as the Nile, Indus, Yellow, Amu and Syr Darya, Rio Grande, and Colorado, which became intermittent during the past 50 years due to human interference. In arid and semiarid regions of North America, most formerly perennial rivers are now intermittent. This

924-872: The surrounding land in Australia. In the Caribbean region, overgrazing is a threat to vegetation areas where there is livestock farming, which is an important source of livelihood and food security for many people. a combination of small scale livestock farming with small ruminants, and mixed farming is practised. However, livestock consume vegetation faster than it can be renewed and this leads to land degradation, loss of vegetative areas, and soil erosion resulting in poor quality feed and reduced livestock yields and income. Also, these grazing lands are critical in controlling carbon dioxide and mitigating risks against severe weather such as floods and droughts. Overgrazing weakens ecological conservation. In New Zealand , overgrazing

957-611: The threat to both flora and fauna . Many bird species have become extinct or endangered, and many of the medium-sized desert mammals are now completely extinct or only exist on a few islands of Australia . Overgrazing can also occur with native species. In the Australian Capital Territory , the local government in 2013 authorised a cull of 1455 kangaroos due to overgrazing. Maisie Carr (1912-1988), Ecologist and Botanist, undertook significant research and studies in overgrazing and established consequences on

990-693: The use of common land in England and Wales was a triumph of conserving a scarce resource using agreed custom and practice. There have been overgrazing consequences in the region Sahel region. The violent herder–farmer conflicts in Nigeria , Mali , Sudan and other countries in the Sahel region have been exacerbated by land degradation and overgrazing. See 2010 Sahel famine . Various countries in Sub-Sahara Africa are affected by overgrazing and resulting ecological effects. In Namibia , overgrazing

1023-442: The usefulness, productivity and biodiversity of the land and is one cause of desertification and erosion . Overgrazing is also seen as a cause of the spread of invasive species of non-native plants and of weeds . Degrading land, emissions from animal agriculture and reducing the biomass in a ecosystem contribute directly to climate change between grazing events. Successful planned grazing strategies have been in support of

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1056-483: The value of most ecosystem functions declines with increasing grazing intensity and that increasing aridity weakens positive impacts of light grazing. Native plant grass species, both individual bunch grasses and in grasslands , are especially vulnerable. For example, excessive browsing by white-tailed deer can lead to the growth of less preferred species of grasses and ferns or non-native plant species that can potentially displace native, woody plants, decreasing

1089-433: Was made of common land, for example in overgrazing, a common would be "stinted", that is, a limit would be put on the number of animals each commoner was allowed to graze. These regulations were responsive to demographic and economic pressure; thus rather than let a common become degraded, access was restricted even further. This important part of actual historic practice was absent from the economic model of Hardin. In reality

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