Effectiveness of stone bunds in controlling soil erosion on cropland in the Tigray Highlands, northern Ethiopia

Abstract

Use of stone bunds to enhance soil and water conservation was first introduced to Tigray, northern Ethiopia in 1981. This study was designed to examine the factors that control the effectiveness of bunds installed on cropland. Qualitative and quantitative assessments of soil loss and sediment accumulation were conducted on 202 plots at 12 representative sites in Dogu'a Tembien district. Mean annual soil loss from the foot of the bunds due to tillage erosion was estimated at 39kgm-'yr-' or 20tha-'yr-', a rate which decreased with increasing age of bund. The assessed mean annual soil loss rate by sheet and rill erosion in the absence of stone bunds is 57 t ha-' yr-'. The mean measured annual rate of sediment accumulation behind the stone bunds is 119 kg m-' yr-' or 59 t ha-' yr-'. The measurements show that the introduction of stone bunds to the region has led to a 68Yo reduction in annual soil loss due to water erosion. This reduction is due to the accumulation of sediment behind the stone bunds, which occurs faster in the early years after construction and decreases as the depression behind the bunds becomes filled with sediment. New stone bunds are particularly effective in trapping sediment in transport, but regular maintenance and increase in height of the bunds is necessary to maintain their effectiveness. The average USLE P factor for stone bunds in the study area is estimated to be 0.32.

Prediction of soil and water conservation structure impacts on runoff and erosion processes using SWAT model in the northern Ethiopian highlands

“…The intervention of SWC measures by the mobilization of the community has a significant soil loss reduction to protect their land from the rainfall-driven soil erosion. The effectiveness of SWC on runoff and sediment yield reduction has been reported in other studies in northern Ethiopia (Gebremichael et al 2005;Haregewyn et al 2005;Descheemaeker et al 2006;Mitiku et al 2006;Nyssen et al 2007Nyssen et al , 2009Dagnew et al 2015Dagnew et al , 2017.…”

Improving efficacy of landscape interventions in the (sub) humid Ethiopian highlands by improved understanding of runoff processes

“…To date, most studies on landscape interventions to control runoff and erosion processes in the Ethiopian highlands have been carried out in the semi-arid Tigray region situated in the northern part of Ethiopia (Nyssen et al, 2000(Nyssen et al, , 2007Gebremichael et al, 2005;Aerts et al, 2006;Descheemaeker et al, 2006a,b;Gebreegziabher et al, 2009;Girmay et al, 2009;Haregeweyn et al, 2013;and many others). Historically, much fewer comprehensive studies have been conducted in the humid highlands where landscape processes, soil types, and agroecological conditions are different.…”

Dynamics of soil erosion rates and controlling factors in the Northern Ethiopian Highlands – towards a sediment budget

“…The measurement of tillage erosion rates involved tracer experiments (Nyssen et al, 2000b) and measurement of volumes of soil removed from the foot of stone bunds (Desta et al, 2005).…”

“…The effectiveness of stone bunds was assessed through comparison of volumes of soil accumulated behind stone bunds over a period of 3-21 years with predicted mean volumes of soil lost from the plot (Desta et al, 2005), as well as through measurements on runoff plots (Nyssen, 2001). Regrowing vegetation in exclosures traps large amounts of sediment transported within the catchment: thickness and areal extent of recently deposited sediment (over a period of 1-20 years) were measured (Descheemaeker et al, 2006).…”

“…Sheet and rill erosion (Figure 4) rates and processes were analysed through measurements on closed and open runoff plots during the period 1999-2001 (Nyssen et al, 2007c) and measurements of soil volumes deposited behind soil conservation structures (Desta et al, 2005).…”