Road Ditches Research Articles

CONTROL OF SEDIMENT EXPORT FROM THE FOREST ROAD PRISM

The effectiveness of four road turnout ditch treatments (vegetation, riprap, sediment fences, and settling basins)in reducing sediment export to the forest floor was evaluated. These four runoff control methods are commonly prescribedto control forest road runoff and sediments. The study utilized runoff samplers, runoff diversion walls, sediment filter bags,and erosion stakes to evaluate runoff concentration reductions through the treatments and sediment export downslope of thetreatments. Settling basin, sediment fence, and vegetation treatments had no significant differences in runoff concentrationreductions, which averaged more than 40%. The riprap was significantly less effective at reducing runoff concentration thanwere either the vegetation or sediment fence. The sediment basins were very effective during smaller storm events, but notduring the largest storms, when they overflowed. The sediment basin exported the least amount of smallersized sedimentthat is likely to be delivered to stream systems.

Influence of aestivation on the survival of Galba truncatula (Mollusca : Gasteropoda) populations according to altitude

after aestivation, to specify the range of their shell heights, and to establish the percentage of G. truncatula which burrowed in soil when summer drying occurred. These investigations were performed using six lowland populations living in central France (alt. 206-282 m) and five highland populations, located in the Massif central (alt. 806-900 m). The survival rate of G. truncatu­ la after flooding dried soil with water was significantly higher in the highland than in the lowland populations (69.5-80.7 % in road ditches, for example, instead of 29.3-33.0%). The mean shell heights of surviving snails and the durations of snail re-acti­ vation in water did not show any significant variation, whatever the origin of snail population. The percentages of snails buried in drying soil were higher in the highland population (13.0 % and 15.0 % of juvenile snails, for example, instead of 4.0 % and 7.7 % in lowland snails). In the lowland population only young snails buried, whereas 5.8-8.3 % of adults in the highland popu­ lation were partially burrowing. The local climate of the sites studied in the Massif central, and the ability of snails to burrow into the mud when stagnant water disappeared in July, might explain the higher survival rate during aestivation.

Effects of forest roads on flood flows in the Deschutes River, Washington

The effects of forest roads on peak flows were examined through a combination of field data collection and modelling in the extensively logged 149 km2 catchment of the Deschutes River, Washington, USA. Based on a field survey, the connectivity of culverts to the channel network was related primarily to hillslope curvature and distance to the natural stream channel. Culvert crest stage recorders operated during winters 1996/97 and 1997/98 demonstrated that higher flows occurred in ditches draining clearcuts compared to forested areas. Contrary to expectation, road cutslope height did not seem to affect culvert peak runoff. A distributed hydrologic model was used to evaluate road effects on peak flows in nine subcatchments (2·2 to 21 km2) of the Deschutes River as well as the Deschutes main stem. The model-predicted increases in the mean annual flood due to forest roads alone ranged from 2·2 to 9·5 per cent, and from 2·9 to 12·2 per cent for the 10 year event. These increases are roughly equivalent to slightly smaller than those predicted for harvest effects alone. Simulated road effects on peak flows were independent of forest harvest state. However, at the hillslope scale, modelled as well as field-monitored road ditch response was dependent on harvest state. Modelled road effects generally increased with flood return period, while vegetation effects decreased. Copyright © 2001 John Wiley & Sons, Ltd.

Effects of roadside transect width on waterfowl and wetland estimates

Strip transects located along roads are commonly used to estimate waterfowl populations and characterize associated wetland habitat. We used data collected in May and early June, 1995, on forty-five 40-km2 plots in North Dakota to evaluate bias of 800-m and 400-m wide roadside transects for sampling wetlands relative to a larger (40-km2) scale and to compare duck abundance at the two widths. Densities of all basins combined and of seasonal basins considered alone were biased high for both transect widths, but mean bias did not differ from zero for temporary or semipermanent basins. Biases did not occur when excavated seasonal and temporary basins (i.e., road ditches) were excluded from the sample. Mean basin density was higher for the inner (400-m) transect width than for the outer transect width (area remaining of the 800-m transect, outside of center 400-m width) for all basins combined and for seasonal and temporary basins. We detected an area-related bias in the occurrence of basins in transects: smaller basins (0.08–1.6 ha) were over-represented in transect samples by 2.9–6.5%, and larger basins (≥11 ha) were under-represented in 800-m transects by 7.3% and in 400-m transects by 16.3%. We compared the distribution of ducks relative to water conditions in the inner and outer transect widths to evaluate whether they were affected by proximity to the road. Mallards (Anas platyrhynchos L.), northern pintails (A. acuta L.), and gadwall (A. strepera L.) responded to water conditions equally in the inner and outer transect widths, but northern shovelers (A. clypeata L.) and blue-winged teal (A. discors L.) responded more strongly to wetlands on the inner than the outer transect width, indicating that estimates of these species would be higher from a 400-m wide transect than from an 800-m wide transect. Differences in an adjustment index, used to account for the portion of basin obscured from view, were highly variable between inner and outer transect widths but did not indicate that use of wider transects was hampered by visibility. Biases of transect sampling need to be carefully considered when extrapolating wetland basin or duck densities from transects to larger landscape scales.

Occurrence and Fate of PAHs from Road Runoff in the South Drainage Basin of Annecy Lake

The nature and concentration of Polycyclic Aromatic Hydrocarbons (PAHs) from main road runoff were evaluated in several potential deposition areas close to Annecy Lake. Investigations were conducted on sediments from road lining ditches, surface sediments, surface water of the lake, Eau Morte river, stagnant water from a natural reserve. Sixteen common PAHs were studied and the concentration determined monthly from February to November, 1997 by High-Resolution Shpol'skii Spectrofluorometry. For liquid samples, the total PAH concentration ranges from 0.07 ng/L (Eau Morte) to 8150 ng/L (ditch water). In the sediments the highest PAHs level (1430 ng/g) was observed for the ditches lining the road and illustrate the significant contribution of road runoff to the contamination of the river. The results evidence the PAH adsorption on particulate matter for ditches and river sediments. PAHs bind preferentially to humic substances in stagnant water of swamp areas. The very low concentrations of PAHs found in Annecy Lake water reflect the importance of marshes in the preservation of this natural ecosystem from road runoff contamination.

Understanding and Reducing Erosion from Insloping Roads

Abstract A computer program can help managers anticipate erosion and sediment delivery attributable to forest roads. The watershed version of the water erosion prediction project (WEPP) predicts road erosion rates within the observed range but overestimates sediment plume lengths. The predicted sources of sediment from an insloping road are mainly from the road ditch and the downslope channel; less sediment comes from the traveled way and the cutslope. Mitigation measures to minimize ditch erosion and channel flow rates will have the greatest effects on reducing sediment delivered from insloped forest roads.

Atrazine, alachlor, and total inorganic nitrogen concentrations of winter wind‐eroded sediment samples1

The objective of this study was to determine if atrazine (2‐chloro‐4‐ethylamino‐6‐isopropyl‐1,3,5‐triazine), alachlor [2‐chloro‐N‐(2,6‐diethylphenyl‐N‐(methoxymethyl)acetamide], or inorganic nitrogen was present on wind‐eroded sediments collected from road ditch areas in mid to late winter. Sediment samples that had been deposited in ditches on top of snow were collected during the winters of 1994, 1995, and 1996 at randomly selected sites in eastern South Dakota and western Minnesota. Atrazine, atrazine metabolites [deethylatrazine (DEA)(6‐chloro‐N‐l‐methylethyl‐l,3,5‐triazine‐2,4‐diamine], and deisopropylatrazine (DIA) (6‐chloro‐N‐ethyl‐l,3,5‐triazine‐2,4‐diamine), and alachlor were determined by gas chromatography. Total inorganic N (NO3 ‐ + NH4 +) concentration was determined with a nitrogen analyzer. In all years, atrazine was detected in at least 72% of the samples, with a mean concentration of 8.9 ug kg‐1 and, while DEA was detected in at least 18% of the samples. Alachlor was detected in at least 27% of the soil samples for all three years with mean sediment concentration of >5 ug kg‐1. Inorganic N concentration of all samples averaged 33 mg kg‐1. These data suggest that deposition of wind‐eroded sediment contributes to nonpoint source contamination of nontarget areas by agrichemicals.

Herbicide Leaching Potential Through Road Ditches in Thin Soils Over an Outwash Aquifer

Shallow glacial outwash aquifers provide water to farms, towns, and major cities. The fact that overlying soils are shallow and provide little protection from leachable chemicals suggests the need for careful management of chemical use. This research was conducted to provide data on the leaching potential of 2,4-D and picloram applied to road ditches over shallow aquifers. A comparison of soil profiles in the ditch and adjoining field indicated that an average of 0.3 m (1 ft) of soil was removed from road ditch soils, leaving very shallow soil profiles over the aquifer material. Cumulative infiltration of water into side slopes and ditch bottoms was measured on representative soils together with gravel road runoff to determine a water balance for the ditch. Undisturbed soil columns were brought into a greenhouse where leaching water could be collected and analyzed for the herbicides, 2,4-D and picloram, the currently used herbicides, which had been applied at recommended rates. The combination of extra leaching water from road runoff added to direct rainfall, and the naturally shallow soils that have been reduced in depth to build the roadbed resulted in two to five times the water passing through to groundwater than through adjoining fields. From 2 to 33% of the applied herbicides came through the undisturbed soil columns after the first storm event. The results indicate that caution should be exercised if the choice is made to use chemical methods of weed control in road ditches.

Sediment Concentrations from Intensively Prepared Wetland Sites¹

Abstract Suspended sediment concentrations were measured in water draining from a 5,900-acre Carolina bay undergoing conversion to loblolly pine (Pinus taeda L.) plantations. Samples were collected during the first storm-flow event of each month between January 1981 and December 1982 from subwatersheds involved in some of several phases of conversion. Suspended sediment concentration in water leaving the bay averaged only 16 mg/1 for 13 storms. Road erosion and ditch installation produced the highest suspended sediment concentrations. Suspended sediment concentrations decreased substantially with increasing distance from the sediment source. Logging and site preparation activities did not cause an appreciable increase in suspended sediment when equipment did not operate in the drainage ditches.

Community planning for satisfactory sewage disposal in permafrost regions

Communities in permafrost regions should be planned so as to facilitate surface drainage and the eventual installation of sewers. Sewage haulage is costly, Sewage is gathered only from the buildings which have holding tanks. Toilet sewage from other residences is hauled away, but wash water and some sewage is spilled on the ground outside which pollutes the soil where children play. In most arctic communities this waste-water cannot percolate away through the soil. Growth of the communities makes the public health problems more critical. The cost of hauling all waste-water is too high to be acceptable. Proposed solutions include the consolidation of communities and their location on hillsides with the streets arranged so as to run down the hill at sufficient grade to provide good drainage in the road ditches (1 % minimum) but not so steeply that needed elevation is wasted.

Elyhordeum Iowense, a New Intergeneric Hybrid in the Triticeae

The "generic" name X Elyhordeum is used for hybrids between various species of Elymus and Hordeum. It has recently been reviewed by Bowden (Canad. J. Bot. 36: 101-123. 1958) who listed eight hybrids. The plants discussed below conform to the generic description of X Elyhordeum. They have the general aspect of Hordeum jubatum L., with which they grow. A specimen was brought in for identification by Mr. Charles Crane, a student in Ames High School, who found the stand. In their fragile rachis, spikelet triads, and slender awns, the plants are similar to Hordeum jubatum, but are sterile. They occur along the grassy road ditch of a, gravelled county road, adjacent to a cornfield in the vicinity of Ames. These apparent hybrids were first seen by me in September, 1964, and have been observed repeatedly since. At least 75 of the plants have been counted along 300 m of the roadside. They occur in the road ditch, in dense turf with such species as Poa pratensis L., Spartina pectinata Link, and Calamagrostis canadensis (MVlichx.) Beauv. Scattered plants of Elymus canadensis L. and a few dicotyledonous herbs are also present. This roadside, like all others in the county, has been repeatedly sprayed with herbicides over a period of years, and the vegetation consisted primarily of grasses. At each point where clumps of the hybrids were observed, Elymus villosus Muhl. ex Willd. and Hordeum jubatum also grew. No trees were present in the immediate vicinity, and from the soil type and topography, it is possible to determine that the original vegetation was prarie. The occurrence of Elymus villosus in such an open habitat is unusual, since this is largely a woodland species. These hybrids are completely sterile and can spread only by the gradual stooling of the clumps. Since the plants are distributed over about 300 m of roadside and occur on both sides of a gravelled road, it is very unlikely that they are the products of a single isolated hybridization, propagated by vegetative spread. In observing the habitat, I found hybrids only immediately adjacent to both parents. Clumps of all sizes and apparent ages can be found, from those consisting of only one or two. culms to vigorous individuals as much as 20 cm across at the base and with many inflorescences. It seems evident, therefore, that this cross occurs readily and repeatedly at this site and that the hybrids establish adjacent to the parents. This. particular hybridization has not been reported before, and we have no indication from Iowa herbarium specimens that it occurs elsewhere in the state. Since theparents cross so freely at this location, the genetic barriers between these parental species must be weak. However, the habitats occupied by Hordeum jubatum and Elymus villosus are very different, and these species may not ordinarily cross because of their ecological differences. Hordeum jubatum usually occupies disturbed roadsides and overgrazed pastures, whereas E. villosus is almost universally foundc