Short‐term erosion rates from a ⁷Be inventory balance

Abstract

Detailed soil erosion studies benefit from the ability to quantify the magnitude of erosion over time scales appropriate to the process. An inventory balance for 7 Be was used to calculate sediment erosion in a 30·73 m 2 plot during a series of runoffproducing thunderstorms occurring over three days at the Deep Loess Research Station in Treynor, Iowa, USA. The inventory balance included determination of the pre-and post-storm 7 Be inventories in the soil, the atmospheric influx of 7Be during the event, and profiles of the 7 Be activity in the soil following the atmospheric deposition. The erosion calculated in the plot using the 7 Be inventory balance was 0·058 g cm, which is 23 per cent of the annual average erosion determined using 137 Cs inventories. The calculated erosion from the mass balance is similar to the 0·059 g cm −2 of erosion estimated from the amount of sediment collected at the outlet of the 6 ha field during the study period and the delivery ratio (0·64). The inventory balance of 7 Be provides a new means for evaluating soil erosion over the time period most relevant to quantifying the prediction of erosion from runoff.

Use of 7Be to document soil erosion associated with a short period of extreme rainfall

“…Although the use of 7 Be measurements involves a number of important requirements and assumptions, related to both the preceding conditions and the occurrence of a discrete period of heavy rainfall that can be expected to cause significant erosion, the approach is likely to be applicable in many parts of the world, in addition to south-central Chile. The successful use of 7 Be measurements in a similar context has already been reported from the UK by Blake et al (1999) and Walling et al (1999), and from the USA by Wilson et al (2003).…”

“…In contrast to 137 Cs,7 Be is a short-lived, naturally occurring, cosmogenic radionuclide with a half-life of only 53 days. This makes it particularly useful for documenting event-based erosion and it has been used successfully in such applications by several workers, including Wallbrink and Murray (1993), Blake et al (1999), Walling et al (1999), Wilson et al (2003) and . This paper reports the use of 7 Be measurements to document soil redistribution within a field at Buenos Aires farm in south-central Chile, associated with a period of very heavy rainfall in autumn 2005.…”

Boron content of Lake Ulubat sediment: A key to interpret the morphological history of NW Anatolia, Turkey

“…And, during this time span, borate-bearing valleys in the SDB were trenched to a maximum of 15 m expressing an erosion rate of 1.4 cm.a -1 . This rate is very high in comparison to long-term erosion but it is very close or similar to short-term ones in different climatic regions (Clayton, 1998;Hinderer, 1999;Wilson et al, 2003). …”

Comparing measurements, ⁷Be radiotracer technique and process-based erosion model for estimating short-term soil loss from cultivated land in Northern Germany

“…An exponential decline of 7 Be with depth indicates equilibrium between deposition and decay. Assuming exponential depth profiles, the 7 Be technique was applied for estimating soil erosion and deposition processes associated with individual periods of heavy rain at scales ranging from plots of a few square meters to fields of a few hectares (Blake et al 1999;Walling et al 1999;Wilson et al 2003;Schuller et al 2006Schuller et al , 2008Porto & Walling 2014). An approach to estimating erosion/deposition rates if 7 Be inventories are not in equilibrium (e.g.…”