Soil erosion assessment—Mind the gap

Abstract

Accurate assessment of erosion rates remains an elusive problem because soil loss is strongly nonunique with respect to the main drivers. In addressing the mechanistic causes of erosion responses, we discriminate between macroscale effects of external factors—long studied and referred to as “geomorphic external variability”, and microscale effects, introduced as “geomorphic internal variability.” The latter source of erosion variations represents the knowledge gap, an overlooked but vital element of geomorphic response, significantly impacting the low predictability skill of deterministic models at field‐catchment scales. This is corroborated with experiments using a comprehensive physical model that dynamically updates the soil mass and particle composition. As complete knowledge of microscale conditions for arbitrary location and time is infeasible, we propose that new predictive frameworks of soil erosion should embed stochastic components in deterministic assessments of external and internal types of geomorphic variability.

Twenty years of soil erosion on‐farm measurement: Annual variation, spatial distribution and the impact of conservation programmes for soil loss rates in Switzerland

“…Even though erosion research has existed for many decades in most countries of the world, and numerous research papers on erosion have been published, there are still major research gaps (Poesen, ). To address the research gaps of soil erosion assessment, accurate measurements and long‐term observations should be attained (Kim et al, ). In a meta‐analysis of soil erosion rates across the world with more than 4000 sites involving various measurement methods, García‐Ruiz et al () showed that a large proportion of the experiments lasted less than 3 years.…”

“…Prasuhn () and Boardman and Evans () also analysed numerous field‐monitoring studies and found very few long‐term studies. Various authors emphasized the high temporal and interannual as well as spatial dynamics and variability and the episodic nature of the triggering processes (García‐Ruiz et al, ; Knox et al, ; Evans and Boardman, , ; Kim et al, ; Fischer et al, ; Batista et al, ; Fiener et al, ; Onnen et al, ). Therefore, they stressed the distinct need for long‐term monitoring studies.…”

“…To address the research gaps of soil erosion assessment, accurate measurements and long-term observations should be attained (Kim et al, 2016). In a meta-analysis of soil erosion rates across the world with more than 4000 sites involving various measurement methods, García-Ruiz et al (2015) showed that a large proportion of the experiments lasted less than 3 years.…”

A Novel Modeling Framework for Computationally Efficient and Accurate Real‐Time Ensemble Flood Forecasting With Uncertainty Quantification

“…Real-time forecasting is an important component of flood risk management and mitigation but is subject to multiple uncertainties caused by meteorological inputs, initial states, model structures, and model parameters (Ajami et al, 2007;Beven, 1989;Mockler et al, 2016;Moradkhani & Sorooshian, 2008). Due to the complexities of natural phenomena represented by equifinality (Beven, 2006;Beven & Freer, 2001), hysteresis (Fatichi et al, 2015;Ivanov et al, 2010;Wei & Dewoolkar, 2006), nonuniqueness (Beven, 2000;McKenna et al, 2003;Kim & Ivanov, 2014;Kim, Dwelle, et al, 2016), nonlinearity (Kim & Ivanov, 2015;Kitanidis & Bras, 1980;Xie & Zhang, 2010), and internal variability (Kim et al, 2016a(Kim et al, , 2016bKim et al, 2018;Lafaysse et al, 2014;Mondal & Mujumdar, 2012;Nikiema & Laprise, 2011), perfect predictions using numerical models are infeasible. The problem exacerbates, if one attempts to simulate constitutive models derived from empirical or phenomenological observations rather than basic conservation laws of physics that would also require embracing a large number of parameters.…”

Evaluating Differences of Erosion Patterns in Natural and Anthropogenic Basins through Scenario Testing: A Case Study of the Claise, France and Nahr Ibrahim, Lebanon

“…Under any circumstance and prior to treating soil erosion, assessing its extent and identifying hotspots are required [13,27]. However, this assessment is not an easy task given the heterogeneity and large spatial/temporal variability of its driving factors [28,29], particularly in Mediterranean landscapes [30] that are characterized by a complexity of slope, climate and land occupation factors [10].…”