Vegetation development in sown field margins and on adjacent ditch banks

The creation of temporal and newly sown field margins for 6 years is a common agri-environment scheme (AES) in the Netherlands. Conservation profits resulting from AES vary over different areas and need further studying. We examined plant species richness in such field margins and adjacent ditch banks in the province of Zeeland, where these linear elements do not experience plant biomass removal after mowing as management strategy. First, during 2 years, we inventoried field margins sown with a wildflower mixture and related the species composition and richness to the age of the margins. In a second assessment, we studied plant species richness on ditch banks protected from arable fields by these margins. Major clusters in a principal component analysis (PCA) on species composition in the field margins showed a succession from sown and ruderal annual species (year 1), to sown perennial species (year 2) and ending with a dominance by tussock forming grass species and Urtica dioica (year 5–6). Total plant species richness decreased with increasing age of the margins, and this was caused by the combination of a decline in sown species and a stable number of not-sown species. The presence of field margins during several years did not result in an increase in plant species richness on adjacent ditch banks. In both the field margins and on the ditch banks, mowing management is not followed by the removal of the cuttings. For plant conservation, the results of these field margins are disappointing, probably due to the lack of a proper management. Therefore, we recommend implementing a hay-making and opening management, to increase plant richness and to reduce noxious weeds in the margins and on the ditch bank

Safe2Ditch Steer-To-Clear Development and Flight Testing

This paper describes a series of small unmanned aerial system (sUAS) flights performed at NASA Langley Research Center in April and May of 2019 to test a newly added Steer-to-Clear feature for the Safe2Ditch (S2D) prototype system. S2D is an autonomous crash management system for sUAS. Its function is to detect the onset of an emergency for an autonomous vehicle, and to enable that vehicle in distress to execute safe landings to avoid injuring people on the ground or damaging property. Flight tests were conducted at the City Environment Range for Testing Autonomous Integrated Navigation (CERTAIN) range at NASA Langley. Prior testing of S2D focused on rerouting to an alternate ditch site when an occupant was detected in the primary ditch site. For Steer-to-Clear testing, S2D was limited to a single ditch site option to force engagement of the Steer-to-Clear mode. The implementation of Steer-to-Clear for the flight prototype used a simple method to divide the target ditch site into four quadrants. An RC car was driven in circles in one quadrant to simulate an occupant in that ditch site. A simple implementation of Steer-to- Clear was programmed to land in the opposite quadrant to maximize distance to the occupants quadrant. A successful mission was tallied when this occurred. Out of nineteen flights, thirteen resulted in successful missions. Data logs from the flight vehicle and the RC car indicated that unsuccessful missions were due to geolocation error between the actual location of the RC car and the derived location of it by the Vision Assisted Landing component of S2D on the flight vehicle. Video data indicated that while the Vision Assisted Landing component reliably identified the location of the ditch site occupant in the image frame, the conversion of the occupants location to earth coordinates was sometimes adversely impacted by errors in sensor data needed to perform the transformation. Logged sensor data was analyzed to attempt to identify the primary error sources and their impact on the geolocation accuracy. Three trends were observed in the data evaluation phase. In one trend, errors in geolocation were relatively large at the flight vehicles cruise altitude, but reduced as the vehicle descended. This was the expected behavior and was attributed to sensor errors of the inertial measurement unit (IMU). The second trend showed distinct sinusoidal error for the entire descent that did not always reduce with altitude. The third trend showed high scatter in the data, which did not correlate well with altitude. Possible sources of observed error and compensation techniques are discussed

Testing of the San Jose Mission Acequia, San Antonio Missions National Historical Park, Bexar County, Texas

The purpose of this project was to locate and identify the acequia madre, or main irrigation ditch, where it ran between the east wall of Mission San Jose and San Jose Drive and to trace out the location of another ditch, part of which was found during road construction in the area in 1981. After confirmation of the location of the main ditch through deed and archival research, a backhoe was used to precisely locate the ditch on the site. The second ditch was relocated and its course followed to the north boundary of the park property in this area. The secondary ditch appears to be a lateral which once took off from the main ditch somewhere north of Pyron Road and rejoined it some distance to the south, in order to irrigate the fields outside the east wall

Abundance, Diversity and Distribution of Benthic Macro-Invertebrates in the Flat Bayou Drainage Area, Jefferson County, Arkansas

The main ditch of Flat Bayou Drainage in north central Jefferson County carries water southward into Plum Bayou which then shortly empties into the Arkansas River. Flat Bayou proper flows northward into Wabbaseka Bayou which in turn flows into the Arkansas River in northeastern Lincoln County. Two sites on the main ditch were sampled for physico-chemical parameters and benthic macroin vertebrates on 9 September, 7 October and 11 November 1978. No visible detrimental effects were attributed to physico-chemical characteristics. Thirty-one below-family taxa and 19 families were found in abundance from zero at one site and date to 3580 per m² at one site and date. Corbicula was by far the most numerous taxon whereas several taxa (e.g. Placobdella, Piscicolarla, Lampsilis, Uniomerus, Campeloma, Berosus and Palpomyia) were represented by a per m² density of 8.6 on one date at one site. Dominance indices were generally greater, and distribution values indicated stronger clumping at Site 1 whereas diversity values were generally greater at Site 2. These indicated the substrate at Site 2 was more suitable for community development

The Architect and the Ditch Digger

“You have an architect and a ditch-digger working together on a construction project. Who gets paid more, and why?” Does a tendency toward abstraction and quantification, a pretense of objectivity, obscure the character, situation and bias from which all economic and political theorems stem? Following the principle that arguments neither arise nor persist in a vacuum, that they live and die by their context and character, we can describe two sorts of response corresponding to two rather timeless worldviews, along with their accompanying “mind-sets”. The degree to which these views indicate differing “kinds” in human nature, beyond which there can be no further reduction to common ground, whether conversely they simply reflect historical and economic circumstance, or to what extent they are both, will be left to the reader. One might discern in the sensibilities described some alignment along traditional epithets of “bourgeois” vs. “working class”, but this is not necessarily so. I will therefore avoid overwrought labels, but admit that such family resemblances speak to a longer historical view and a persistent problematic

Redescription of \u3ci\u3eMicropsectra Polita\u3c/i\u3e (Diptera: Chironomidae) with the Female and Immature Stages

(excerpt) Malloch (1915) described Micropsectra polita (as Tanytarsus politus) from males collected along the banks of Central Dredge Ditch at Easton, Mason County, llIinois. Females of this species were not collected at that time. On 12 February 1974, males, females, and larvae were collected from a small spring-fed seep (Fig. 1) running into Muncie Pond, in Vermilion County, llIinois

Simulating the effects of spatial configurations of agricultural ditch drainage networks on surface runoff from agricultural catchments

The study of runoff is a crucial issue because it is closely related to flooding, water quality and erosion. In cultivated catchments, agricultural ditch drainage networks are known to influence runoff. As anthropogenic elements, agricultural ditch drainage networks can therefore be altered to better manage surface runoff in cultivated catchments. However, the relationship between the spatial configuration, i.e., the density and the topology, of agricultural ditch drainage networks and surface runoff in cultivated catchments is not understood. We studied this relationship by using a random network simulator that was coupled to a distributed hydrological model. The simulations explored a large variety of spatial configurations corresponding to a thousand stochastic agricultural ditch drainage networks on a 6.4 km2 Mediterranean cultivated catchment. Next, several distributed hydrological functions were used to compute water flow-paths and runoff for each simulation. The results showed that (i) denser networks increased the drained volume and the peak discharge and decreased hillslopes runoff, (ii) greater network density did not affect the surface runoff any further above a given network density, (iii) the correlation between network density and runoff was weaker for small subcatchments (< 2 km2) where the variability in the drained area that resulted from changes in agricultural ditch drainage networks increased the variability of runoff and (iv) the actual agricultural ditch drainage network appeared to be well optimized for managing runoff as compared with the simulated networks. Finally, our results highlighted the role of agricultural ditch drainage networks in intercepting and decreasing overland flow on hillslopes and increasing runoff in drainage networks

Archaeological evaluation : New High School, Matthews Lane, Gorton, Manchester

In February 2017, Salford Archaeology was commissioned by Laing O’Rourke to undertake an archaeological evaluation on land located adjacent to Matthews Lane, Gorton, Manchester (centred on NGR SJ 87861 95024). The Site Area comprises an open space heath land currently undeveloped within the Gorton area of Manchester. The assessment aimed to identify, as far as possible, the nature, extent and significance of the archaeological resource, so as to enable informed recommendations to be made for the future treatment of any surviving remains. Trenches were located to investigate the remains of the late 19th century Yew Tree Farm and the possibility of remains associated with Nico Ditch. Trench 1 was excavated over the site of the farmhouse and was able to uncover limited evidence of structures. Trench 2 was located to investigate the southern farm outbuildings and possible deposits associated with Nico Ditch and uncovered remains of features relating to the farm only. A third was excavated over the site of the main barn but was abandoned due to the removal of archaeological deposits by later landfill. The evaluation was able to confirm that evidence of 19th century structures remains within 15m of the present site boundary but that all other deposits outside this area were removed by later landfill activity. Nevertheless those areas to have escaped the excavation of the clay pit do retain moderately well preserved evidence of earlier occupation

Master\u27s Project: Assessing Unpaved Road Runoff in the Mad River Watershed of Central Vermont

Over half of the local town roads in Vermont are unpaved (VBB, 2009). In the Mad River Watershed of central Vermont, 58% of the roads are unpaved. These compacted surfaces, despite their lack of tar, provide hundreds of miles of impermeable surfaces that extend the stream network, and transport runoff and pollutants to our water bodies. In this project, 12 sites within the Mad River watershed were monitored with the goal of evaluating the amount of runoff that is generated on the road surface itself as compared to flow that enters roadside ditches via groundwater seeps and overland flow from adjacent land. Each site was monitored for stage using an ISCO 6712 Automated Water Sampling Unit with an attached pressure transducer, and rating curves were developed from manual volume measurements in order to connect stage values with runoff volumes. Each site was mapped to determine the contributing road surface drainage area, and these values were compared to the slope of linear regressions developed for storm precipitation and runoff totals. Modeled road surface hydrographs were developed for 11 of the 12 sites, using the rational method, and were compared to hydrographs developed using measured runoff. One-quarter of the sites appear to have regular runoff contributions that originate outside of the bounds of the mapped drainage area. Five of the eleven sites also displayed seasonal variations where runoff originated outside of the mapped road surface area during times of greater land saturation. These results indicate that roads can sometimes contribute far more than just the runoff that is generated on their surface alone, and that the quantity and occurrence of these external contributions may increase with an increase in the drainage source area that can be seen in seasons when the ground is saturated

The effects of peatland forest ditch maintenance on suspended solids in runoff

In 1990–1994, the effect of peatland forest ditch maintenance on the concentration of suspended solids in runoff water was studied in Finland in 37 catchments by using a short pre-treatment period and comparing with 31 control areas. On the average, the concentrations of suspended solids were 4–5 mg l–1 in the control areas and in the treatment areas before ditch network maintenance. During a period of 1–3 years after maintenance, the concentration of suspended solids in the water leaving ditch network and entering sedimentation ponds averaged 45.8 mg l–1. The magnitude of the increase depended on the area subjected to ditch maintenance as well as the prevailing soil type at the bottom of the ditches. Measured as 1–3 year averages, only half of the sedimentation ponds reduced the concentration of suspended solids. During the first year after ditch network maintenance, the suspended solids concentration in the water entering the sedimentation ponds averaged 71.3 mg l–1 and the water leaving the ponds 58.1 mg l–1. In the second year, the corresponding values were 26.8 mg l–1 and 21.1 mg l–1 and in the third year, 12.8 mg l–1 and 12.4 mg l–1, respectively