Selection of hill-country pasture measurement sites by interpretation of sequential aerial photographs

Stephens, P. R.

doi:10.1080/03015521.1981.10427799

Cited by 10 publications

(4 citation statements)

References 1 publication

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“…The earliest aerial photography was flown in 1943 with subsequent surveys in 1965, 1977, 1994, and 2010 (Table I). An additional aerial survey had been flown across part of the farm property in 1979, by the then New Zealand Ministry of Works and Development (the film database is maintained by Landcare Research, 2011) for the purpose of mapping landslides and vegetation in the early pasture productivity trials (Trustrum and Stephens, 1981). An additional aerial survey had been flown across part of the farm property in 1979, by the then New Zealand Ministry of Works and Development (the film database is maintained by Landcare Research, 2011) for the purpose of mapping landslides and vegetation in the early pasture productivity trials (Trustrum and Stephens, 1981).…”

Section: Aerial Photographymentioning

confidence: 99%

“…In preparation for locating pasture exclosure cages for the first of subsequent pasture productivity trials , Trustrum and Stephens (1981) dated and mapped landslides at a number of pasture trial sites using archived stereo aerial photography ( Figure 1). Landslides were dated at pre-1941, 1941, 1961 and 1977. In the trial, dry matter production, botanical composition and soil nutrients (total-C, N, P) were measured over a threeyear period on landslide scars and uneroded ground.…”

Section: Study Sitementioning

confidence: 99%

“…Imagery on Google Earth covering the study site (captured in 2003, 2008 and 2010) was also used to assist in identifying the most recent landslide events. An additional aerial survey had been flown across part of the farm property in 1979, by the then New Zealand Ministry of Works and Development (the film database is maintained by Landcare Research, 2011) for the purpose of mapping landslides and vegetation in the early pasture productivity trials (Trustrum and Stephens, 1981). The survey comprised two adjacent flight runs -MS52C [red, green, and blue (RGB) colour film] and MS52CIR [near infrared, red, and green (CIR) colour infrared film]captured at a film scale of 1:5100 ( Figure 1).…”

Section: Aerial Photographymentioning

confidence: 99%

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Slope control on the frequency distribution of shallow landslides and associated soil properties, North Island, New Zealand

Rose

2012

Earth Surf Processes Landf

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The extrapolation of results from field trials to larger areas of land for purposes of regional impact assessment is an important issue in geomorphology, particularly for landform properties that show high stochastic variability in space and time, such as shallow landslide erosion. It is shown in this study, that by identifying the main driver for spatial variability in shallow landslide erosion at field scales, namely slope angle, it is possible to develop a set of generic functions for assessing the impact of landslides on selected soil properties at larger spatial scales and over longer time periods. Research was conducted within an area of pastoral soft‐rock Tertiary hill country in the North Island of New Zealand that is subject to infrequent high intensity rainfall events, producing numerous landslides, most of which are smaller than several hundred square metres in size and remove soil to shallow depths. All landslides were mapped within a 0·6 km2 area and registered to a high resolution (2 m) slope map to show that few landslides occur on slopes < 20° and 95% were on slopes > 24°. The areal density of landslides from all historical events showed an approximately linear increase with slope above 24°. Integrating landslide densities with soil recovery data demonstrates that the average value of a soil property fluctuates in a ‘saw‐tooth’ fashion through time with the overall shape of the curve controlled by the frequency of landslide inducing storm events and recovery rate of the soil property between events. Despite such fluctuations, there are gradual declines of 7·5% in average total carbon content of topsoil and 9·5% in average soil depth to bedrock, since the time of forest clearance. Results have application to large‐scale sediment budget and water quality models and to the New Zealand Soil Carbon Monitoring System (CMS). Copyright © 2012 John Wiley & Sons, Ltd.

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Section: Aerial Photographymentioning

confidence: 99%

Section: Study Sitementioning

confidence: 99%

Section: Aerial Photographymentioning

confidence: 99%

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Slope control on the frequency distribution of shallow landslides and associated soil properties, North Island, New Zealand

Rose

2012

Earth Surf Processes Landf

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“…However, pastoral farming and associated clearing of bush, scrub, and fern began in the region in 1884 (MacGregor 1970 Measurement sites Forty-five measurement sites were selected and dated using an aerial photographic technique (Trustrum & Stephens 1981). They were located on scars of 4 different ages (pre-1942, 1942, 1970, and 1977), accumulation zones arising from 1970 and 1977 erosion events, and footslope ridges (Fig 1 b).…”

Section: Trial Sitementioning

confidence: 99%

Effect of soil slip erosion on Wairoa hill pasture production and composition

Douglas¹,

Brown²

1986

New Zealand Journal of Agricultural Research

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Dry matter production, botanical composition, soil fertility parameters, and foliar nutrient concentrations were measured on hillslope pastures in Wairoa in the North Island of New Zealand, for up to 3 years starting in 1982. Measurement sites were on 10 physiographically different landform units (pre-1942, 1942, 1970, and 1977 slip scars, 1970 and 1977 accumulation zones, footslope ridges, spurs, flats, and lower pumice ridges) representing the erosion-sedimentation continuum of the area. Average annual pasture production on pre-1942 scars was 7.5 t dry matter/ha. Similar yields were recorded from 1942 and 1970 scars, but the 1977 scars produced only 2.6 t dry matter/ha. A model derived from analysis of these results indicated that pasture recovery was exponential-recovery was most rapid in the first 10 years after slipping, and after 30 years there was no further increase in production. The proportions of the grass and clover pasture components increased and decreased, respectively, with increasing length of time since slipping. Soil pH and calcium levels generally declined with scar age and were lowest for spurs, but the reverse trend was generally true for potassium, phosphate retention, and sulphur. Moisture content and phosphate retention were higher on treads than scarps. All other landform units produced more dry matter annually than any slip scar. The results show the necessity of studying landform units separately in any research on hill country pastoral productivity, and confirm many of the findings from previous work in the Wairarapa, particularly those relating to the rate of pasture recovery.

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A Review of Scale Dependency in Landslide Hazard and Risk Analysis

Glade¹,

Crozier²

2005

Landslide Hazard and Risk

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Landslides are part of the natural environment and affect economy and communities worldwide at various scales. Consequently, methods of assessing landslide risk depend heavily on specific demands. Within this frame, spatial landslide hazard and risk assessments are an important tool to support local and regional communities. These assessments include hazard and risk analysis, risk perception and a sustainable risk management. In Bíldudalur, Iceland, hazard analysis was performed at 1:5,000 scale and is build on landslide hazard determined by a combination of heuristic analysis, in particular geomorphological assessment, and process modelling. The investigation was focussed on debris flows and rock falls only. Resulting landslide maps give run-out distances of different sized landslide events. This information is assigned to hazard classes expressing through its magnitude the probability of occurrence of a given magnitude within a given region. Risk analysis in Rheinhessen, Germany is based on landslide hazard derived from multivariate statistical analysis at scale 1:25,000. Landslide types were not differentiated specifically, however, most landslides in this region are shallow, translational earth and debris slides and flows. Risk elements were mapped and categorized from aerial photographs and land use plans. Potential damage was calculated as average values based on official German statistics sources. Due to missing information, vulnerability was assigned as 1 (highly vulnerable) -thus analysis returns a worst case scenario. Resulting landslide risk map identifies high risk areas in urban settings. Within their scale of investigation, both approaches demonstrate their importance for prevention strategies, in particular for planning and mitigation purposes. The examples are linked to an overall scheme of landslide risk assessment, which has the potential to include other natural hazards and consequently might lead to a mutli-natural risk assessment.

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Selection of hill-country pasture measurement sites by interpretation of sequential aerial photographs

Cited by 10 publications

References 1 publication

Slope control on the frequency distribution of shallow landslides and associated soil properties, North Island, New Zealand

Slope control on the frequency distribution of shallow landslides and associated soil properties, North Island, New Zealand

Effect of soil slip erosion on Wairoa hill pasture production and composition

A Review of Scale Dependency in Landslide Hazard and Risk Analysis

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