Cast-in-place 2-foot concrete trapezoidal flow-measuring flumes /

Issued Nov. 1977.

黄土坡面下坡位土壤侵蚀过程的模拟试验

在中国科学院水利部水土保持研究所,采用2个不同坡长小区室内模拟降雨试验方法,对黄土坡面下坡位侵蚀过程进行研究。结果表明:1)坡面下坡位侵蚀模数随降雨过程、降雨强度及坡度的变化均具有大小交错,上下波动的特征,侵蚀模数随降雨过程的变化总体呈先上升后趋于稳定的态势,随降雨强度的增大而增加,随坡度的增大而先增大后减小,再增大再减小;2)坡面上、下坡位侵蚀模数随降雨过程、坡度及降雨强度的变化均具有明显差异,下坡位明显不如上坡位;3)坡面上坡位汇流和下坡位产流与坡面上坡位输沙对坡面下坡位侵蚀模数的影响可用二元线性方程很好地描述,前者的贡献率为47.8%,后者为20.4%;只通过观测分析小区平均侵蚀特征得出的坡面侵蚀过程,掩盖了坡面下坡位的真实侵蚀过程,采取水土保持措施减少坡面上坡位汇流及增加降雨就地入渗,可以有效地治理坡面下坡位的水土流失。

Modification to the Hardisty equation, regarding the relationship between sediment transport rate and particle size

Bagnold-type bed-load equations are widely used for the determination of sediment transport rate in marine environments. The accuracy of these equations depends upon the definition of the coefficient k(1) in the equations, which is a function of particle size. Hardisty (1983) has attempted to establish the relationship between k(1) and particle size, but there is an error in his analytical result. Our reanalysis of the original flume data results in new formulae for the coefficient. Furthermore, we found that the k(1) values should be derived using u(1) and u(1cr) data; the use of the vertical mean velocity in flumes to replace u(1) will lead to considerably higher k(1) values and overestimation of sediment transport rates.

Biofilm Complexity Controls Fine Particle Dynamics in Streams

Most models of riverine eco-hydrology and biogeochemistry rely upon bulk parameterization of fluxes. However, the transport and retention of carbon and nutrients in headwater streams is strongly influenced by biofilms (surface-attached microbial communities), which results in strong feedbacks between stream hydrodynamics and biogeochemistry. Mechanistic understanding of the interactions between streambed biofilms and nutrient dynamics is lacking. Here we present experimental results linking microscale observations of biofilm community structure to the deposition and resuspension of clay-sized mineral particles in streams. Biofilms were grown in identical 3 m recirculating flumes over periods of 14-50 days. Fluorescent particles were introduced to each flume, and their deposition was traced over 30 minutes. Particle resuspension from the biofilms was then observed under an increased stream flow, mimicking a flood event. We quantified particle fluxes using flow cytometry and epifluorescence microscopy. We directly observed particle adhesion to the biofilm using a confocal laser scanning microscope. 3-D Optical Coherence Tomography was used to determine biofilm roughness, areal coverage and void space in each flume. These measurements allow us to link biofilm complexity to particle retention during both baseflow and floodflow. The results suggest that increased biofilm complexity favors deposition and retention of fine particles in streams.

Patrimonis fràgils: sèquies i recs

El petit però ric patrimoni hidràulic (preses, rescloses, sèquies, recs...) del país testimonia l’intens aprofitament que han tingut els nostres rius al llarg de la història. Però aquest patrimoni encara no gaudeix del reconeixement i la valoració que comencen a tenir els grans edificis o conjunts del patrimoni industrial vinculat a l’aigua

[Ressenya del llibre, Los regadíos históricos españoles: paisajes culturales, paisajes sostenibles, de Jorge Hermosilla (dir.)]

Ressenya de l'obra dirigida per Jorge Hermosilla i titulada "Los regadíos históricos españoles: paisajes culturales, paisajes sostenibles", publicada l'any 2010. Es trata d'un estudi realitzat per la Direcció General de l’Aigua, del Ministeri de Medi Ambient sobre els recs històrics espanyols des d’una perspectiva cultural. L’obra s’estructura en dues parts: la primera és una aproximació històrica dels conreus de regadiu espanyols i a la segona s'analitzen amb més detall una selecció de sistemes de rec històrics

Seawater carbonate chemistry and calcification rate in flume experiment

Ocean acidification (OA) poses a severe threat to tropical coral reefs, yet much of what is know about these effects comes from individual corals and algae incubated in isolation under high pCO2. Studies of similar effects on coral reef communities are scarce. To investigate the response of coral reef communities to OA, we used large outdoor flumes in which communities composed of calcified algae, corals, and sediment were combined to match the percentage cover of benthic communities in the shallow back reef of Moorea, French Polynesia. Reef communities in the flumes were exposed to ambient (400 ?atm) and high pCO2 (1300 ?atm) for 8 weeks, and calcification rates measured for the constructed communities including the sediments. Community calcification was reduced by 59% under high pCO2, with sediment dissolution explaining ~ 50% of this decrease; net calcification of corals and calcified algae remained positive but was reduced by 29% under elevated pCO2. These results show that, despite the capacity of coral reef calcifiers to maintain positive net accretion of calcium carbonate under OA conditions, reef communities might transition to net dissolution as pCO2 increases, particularly at night, due to enhanced sediment dissolution.

Modified Parshall flume /

Mode of access: Internet.

Arizona Canal Diversion Channel : selection of roughness coefficients for designing the concrete-lined channel /

"September 1985."

Sediment suspension and turbulence in an oscillating flume /

"April 1977."

Damage prog[r]ession on rubble-mound breakwaters /

Includes bibliographical references: (p. 196-201).

Measuring seepage loss in irrigation canals : (tentative procedures for ponding and seepage meter tests) /

Mode of access: Internet.