Particle size distribution and settling velocity of sediments in water diverted from the Yellow River during border-strip irrigation

Li, J., Fei, L., Chen, Z., & Sun, X. (March-April, 2017). Particle size distribution and settling velocity of sediments in water diverted from the Yellow River during border-strip irrigation. Water Technology and Sciences (in Spanish), 8(2), 31-41. Diversion of river water for irrigation is an important factor in sustainable agricultural development in the Yellow River basin. This study examines patterns in the advance of sediment in irrigation water diverted from the Yellow River during border-strip irrigation. An irrigation experiment was carried out on a 1.8 m-wide strip and a 2.7 m-wide strip of a fruit field in order to observe the advance rate of irrigation water, the distribution of settled sediment, and the concentration and particle size distribution of sediment in the water flow. The settling velocity of sediment particles was then calculated using an empirical formula. The results show that the irrigation water gradually slowed as it advanced along the strip length, and the amounts of deposited particles decreased from the top ends of the strips to their bottom ends. The decrease was especially sharp on the section of each strip between 40 and 120 m from the water pipe outlet. Overall, the size of particles carried by the irrigation water fell within the range of 0.004 to 0.016 mm, with coarse and fine particles making up small proportions of the sediment. The concentration of coarse particles was higher at the top ends than at the bottom ends, while the concentration of fine particles was higher at the bottom ends than at the top ends. Water content in the soil at several locations varied significantly before and after irrigation, and the deposition of sediment was found to exert a great influence on the infiltration of irrigation water. The particle size distribution of the sediment deposited along the strips accords with the law of sedimentation in that coarse particles accumulated primarily at the top ends of the strips as a result of high settling velocity. Moreover, the results demonstrate that it is feasible to simplify the water flow over the field to open-channel flow when calculating settling velocity. However, the formula for calculating settling velocity needs further modification to take into account the influences of flume rate and the scouring action of irrigation water on the surface sediment deposited on the strips

The Sands of Angkor: A Sediment Record of the Later Angkorian Channel Network

During the 1950s Bernard Phillipe Groslier hypothesised that a channel network built by the Angkorians was utilised as a source of irrigation for the production of an agricultural surplus (Groslier 1979). He further proposed that some \failure" of the channel system was causal to the demographic collapse of the city. Criticisms of the theory for lack of evidence were thoroughly debunked by Christophe. Pottier (1999) who systematically documented numerous archaeological features spread over the landscape surround the central temple complex to the south, D. Evans (2007) continuing and completing the work to the north. The resulting map demonstrated the existence of a channel network linking the central water reservoir with the wider agricultural lands. This study documents the stratigraphy of sediments preserved within former Angkorian channels based on desktop terrain analyses, pedestrian field survey, ground-penetrating radar, borehole sampling, hand excavation, particle-size analysis and micromorphology. The results show that the recharge of the channel network was reduced abruptly at a critical node, causing irreversible of recharge to the south. The reduction of recharge can be linked directly to the establishment of the Siem Reap River and its subsequent incision into the substrate. That event is well known and has previously been thought to have occurred relatively early in the Angkorian Period. However, reappraisal of the assumed flow directions along Angkorian channels shows clearly that the establishment of the Siem Reap River must have occurred after the construction of the Jayatataka and therefore much later in the Angkorian Period, well timed for a causal role in the demographic collapse of the city

Coastal Stormwater Management Through Green Infrastructure: A Handbook for Municipalities

Coastal Stormwater Management through Green Infrastructure: A Handbook for Municipalities (Handbook) is designed to assist coastal municipalities within the Massachusetts Bays Program (MassBays) area to incorporate green infrastructure into their stormwater management planning as they respond to MS4 stormwater permit requirements, review development proposals, and retrofit existing municipal facilities and sites. The MassBays Program can assist those municipalities in using this Handbook to facilitate the use of green infrastructure and address stormwater runoff

Proceedings of the regional technical conference on flood control in Asia and the Far East

The various studies carried out by the Bureau of Flood Control are being published as a “Flood Control Series.”  The first number of the series, entitled “Flood Damage and Flood Control Activities in Asia and the Far East,&rdquo

Geology of southern Nelson County, North Dakota

Southern Nelson County occupies 576 square miles in northeastern North Dakota (Twps. 149-152 N., Rgs. 57-62 W.). Its surface is mantled with glacial drift resting unconformably on the Cretaceous Pierre Shale, which is exposed along the Sheyenne River Valley and the Stump Lake Basin. The entire mantle of glacial drift is part of the Coleharbor Formation, which, in southern Nelson County, averages 45 feet thick with a maximum thickness over 200 feet. Drill-hole data and missile site excavations provide good evidence for the existence of multiple drift sheets, including layers of till separated by more than 25 feet of outwash, several buried oxidized zones, and buried soil horizons. Evidence for pre-Wisconsinan drift is based on the discovery of com pact and jointed till in the Minuteman Missile site excavations. The primary lithologies of the Coleharbor Formation include non-bedded diamicton, indistinctly bedded gravel, poorly bedded sandy silt, ·cross bedded sand and horizontally ledded silt. Most of the units contain an abundance of shale particles with some having shale cobbles 6- to 8-inches in diameter. The maximum thickness of the Coleharbor Formation occurs in two preglacial alleys, the Hamar Valley and the McVille Channel, both in the southwestern corner of the county. The McVille Channel is more than 200 feet deep along its entire length, but its gradient direction is yet unknown. The Hamar Valley is a much broader valley than the McVille Channel. It has a northward gradient and is also more than 200 feet deep along most of its extent in southern Nelson County. Because of the, Northward gradient of the Hamar Valley and other buried channels west of Nelson County, the gradient of the McVille Channel is also assumed to be northward. The surface drift of Nelson County was deposited during the retreat of the Leeds Lobe in late Wisconsinan time. Deglaciation of the county began about 13,000 radiocarbon years B.P. upon the retreat of the ice from the McHenry and Cooperstown moraines in the south western corner of the county. The next prolonged stand of the glacier margin occurred at about 12,900 radiocarbon years B.P. depositing the North Viking and Kloten moraines. The Kloten Moraine may be the northward extension of the Luverne Moraine, previously mapped in the counties to the south. Neither the North Viking Moraine nor the Kloten Moraine is a very striking feature. Relief increases only gradually over fairly broad areas and both moraines have doughnut shaped ridges, indicating stagnant ice deposition. Such ridges are especially abundant in the northern part of the Kloten Moraine. During the deposition of the North Viking and K1oten moraines the glacial Sheyenne River was formed. It originated as a small proglacial stream whose headward erosion captured the overflow of glacial Lake Souris, enlarging its channel to a width of 3000 feet and a depth of 100 feet. The resulting average annual discharge of the glacial Sheyenne River is estimated to have been about 500,000 cubic feet per second. The retreat of the glacier from the North Viking Moraine initiated the formation of the glacial ancestors of two of the largest lakes in North Dakota, Devils Lake and Stump Lake. During maximum lake levels water probably reached an elevation of about 1460 fee.t, although little evidence of this strandline remains. The highest strandline presently common to both takes is 1450 feet, 8 feet below the Big Stony Spillway threshold

A study of sedimentation in a well regulated major drainage basin - the Monongehala, Allegheny and upper Ohio Rivers

This investigation is concerned with the study of various programs employed in reducing and controlling sediment. The measures employed by the U.S. Soil Conservation and Forestry Services to control and reduce erosion, the primary source of sediment, was studied. The flood control and river navigation structures constructed and operated by the U.S. Army Corps of Engineers and the effect of these structures on sedimentation was also evaluated. State and local community regulation and control of exploited natural resources was studied to determine their influence on the generation and control of sediment.The Allegheny, Monongehala and upper Ohio River Drainage Basin has the most advanced programs to provide flood control and navigation facilities of the ten major basins in the United States. Sediment carried and deposited by the streams has been reduced to increase the design life and reduce maintenance costs for these structures.The acidity of the soil and waters has influenced the amount of sediment carried in suspension. Reducing this acidity to more common neutral or slightly basic waters may increase the sediment load. Further research is needed in soil and water chemistry to determine if this will occur and to develop effective control measures --Abstract, page ii

Global alarm : dust and sandstorms from the world's drylands

This collection of essays and case studies are presented to analyse factors contributing to dust and sandstorms with examples of measures to keep the menace under control. It considers the relationship between weather, climate and dust storms and examines the mechanisms by which dust and sand are transported. Experiences show that past policies on land-use and the promotion of unsustainable farming systems were the root cause of most disasters. The socio-economic aspects of dryland degradation need to be given more attention. Success stories on effective measures in mitigating the effects of sand-dust storms are reviewed. Progress in finding suitable indicators and monitoring systems to forecast, mitigate and prevent dust storms are featured. Produced and supported by: the Government of the Netherlands, Asia Regional Coordinating Unit, Secretariat of the United Nations Convention to Combat Desertification (UNCCD) in collaboration with the China National Committee for Implementation of UNCCD, Environment and Natural Resources Development Division, UNEP/ROAP, FAO/RAPA, and UNESCO, Beijing Office.Supported by The Government of the Netherland