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\begin{document}

\title{Connectivity between land, water, and people: integrating process
concepts and assessment evidence across disciplines for co-design of
soil erosion solutions}



\author[1]{W.H. Blake}%
\author[2]{Claire  Kelly}%
\author[2]{M Wynants}%
\author[3]{Aloyce Patrick}%
\author[1]{Shaun Lewin}%
\author[4]{Joseph Lawson}%
\author[3]{Emmanuel Nasolwa}%
\author[1]{Annabel Page}%
\author[5]{Mona Nasseri}%
\author[6]{Carey Marks}%
\author[1]{David Gilvear}%
\author[3]{Kelvin Mtei}%
\author[3]{Linus Munishi}%
\author[3]{Patrick Ndakidemi}%
\affil[1]{Plymouth University}%
\affil[2]{University of Plymouth}%
\affil[3]{Nelson Mandela African Institute of Science and Technology}%
\affil[4]{Arhwithrans Surveys Ltd}%
\affil[5]{Schumacher College}%
\affil[6]{Scarlet Design}%


\vspace{-1em}



  
  \date{June 14, 2024}


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\selectlanguage{english}
\begin{abstract}
Soil resources in East Africa are being rapidly depleted by erosion,
threatening food-, water- and livelihood security in the region. Here we
demonstrate how integration of evidence from natural and social sciences
has supported community-led change in land management in an
agro-pastoral community in northern Tanzania impacted by soil erosion.
Drone survey data and geospatial analysis of erosion extent and risk,
supported by communication of `process' and `structural' hydrological
connectivity, was integrated with local environmental knowledge within
participatory community workshops. Rill density data were compared
between cultivated plots that had been converted from pastoral land
recently and more established plots where slow-forming terrace
boundaries were more established. Slope length and connectivity between
plots were key factors in development of rill networks. At the two
extremes, recently converted land had a rill density ca 14 times greater
than equivalent established slow forming terraces. Direction of
cultivation, regardless of plot boundary orientation with contours, also
enhanced rill development. Evidence of this critical time window of
hillslope-scale rill erosion risk during early phases of slow-forming
terrace development successfully underpinned and catalysed a
community-led tree planting and grass seed sowing programme to mitigate
soil erosion by water. This was grounded in an implicit community
understanding of the need for effective governance mechanisms at both
community and District levels, to enable community-led actions to be
implemented effectively. The study demonstrates the wide-reaching impact
of integrated and interdisciplinary `upslope-downslope' thinking to
tackle global soil erosion challenges.%
\end{abstract}%



\sloppy


\emph{Keywords: land degradation, agro-pastoral, drought, erosion,
co-design}



\textbf{1. Introduction}

\emph{1.1 Soil erosion challenges in East Africa}

The East African region harbours rich natural resources that exist in
sharp contrast across the landscape (Veldhuis et al., 2019). These areas
are populated with varied human and livestock densities and while the
landscape provides many ecosystem services, provision is hampered by
human activity and land degradation that include soil erosion. Climate
changes, ecosystem degradation, biodiversity losses and sociopolitical
pressures all impact development, conservation and livelihoods of
socio-ecological systems of which majority of communities rely on across
the region.

Soil resources in East Africa are being rapidly depleted by erosion,
threatening food-, water- and livelihood security in the region (Wynants
et al. 2019; Cobo et al., 2010; Oldeman, 1991). While soil and land
resources are progressively being depleted the population, with
associated needs for livelihoods, food, fibre, and other resources is
expanding (FAO, 2019). Agricultural intensification and economic
diversification are hampered by a lack of available knowledge, skills
and agricultural technology (Korotayev and Zinkina, 2015) and as a
result, an increasing number of farmers are pushed to seek more land to
establish agricultural operations, causing a marked shift from naturally
vegetated landscapes towards agricultural landscapes (Jayne et al.,
2014; Odgaard, 2002). Policies of sedentarisation, privatisation and
confinement within administrative boundaries have impeded the mobility
of previously nomadic pastoralist communities (Homewood et al., 2004).
Moreover, pastoral communities are also experiencing internal pressures
due to higher livestock and other inequality existing among gender and
other community social groups, rapid changes in herd sizes and stocking
densities (both expansion and contraction), shifts towards the need for
external employment opportunities and increased competition over grazing
resources (Rabinovich et al., 2019; Rufino et al., 2013). A combination
of all these and other factors have led to a tripling of the livestock
numbers in the last 50 years (FAO, 2019) with increasing the local
densities of domestic grazers in many areas, leading to overgrazing and
trampling of the soil (Little, 1996; Ruttan and Borgerhoff Mulder,
1999). Furthermore, the high reliance on natural vegetation as a source
of fuel, construction materials and fodder in both the urban and rural
populations is resulting in substantial exploitation pressures on
forests and woodlands (Hiemstra-van der Horst and Hovorka, 2009). The
conjunction of these multiple pressures has increased rates of surface
runoff, soil erosion, gully incision and downstream sediment transport
(Blake et al., 2018; Vanmaercke et al., 2014; Wynants et al., 2020).
Furthermore, these processes are potentially amplified by natural
rainfall variations (Ngecu and Mathu, 1999) and projected increases in
extreme climatic events e.g. drought followed by extreme rainfall
(Nearing et al., 2004). East-Africa's environments/ecosystems are highly
dynamic in both time and space, posing substantial challenges to the
communities that are dependent on them and the development of
sustainable land management plans.

\emph{1.2 Integration of hydrological and socio-economic connectivity
concepts in land management plans}

Interventions to reduce overland flow and soil erosion by water range in
spatial scale from the farm plot to hillslope and catchment level. The
conservation agriculture (CA) approach (International Institute of Rural
Reconstruction and African Conservation Tillage Network., 2005; Kassam
et al., 2019) centres around the mitigation of on-site soil erosion
effects on cultivated land, where soil conserving cropping practices
help reduce erosion and water run-off. Three key interventions that are
essential to CA, however, are applied to different extents and
site-specific contexts. First, minimum or no-tillage practice reduces
soil disturbance, supports higher infiltration capacity and reduces the
risk of overland flow. Second, permanent cover of soil by vegetation
and/or use of crop residues as mulch reduces rain splash and
compaction/crusting of the soil surface. Third, crop rotations and
intercropping, even though their main aim is to increase soil fertility
and yield, consequentially improve soil organic matter content, increase
soil aggregate stability and hence help reduce erodibility. Edge-of-plot
attenuation features (e.g. vegetative barriers, ditches, bunds, buffers)
mitigate both on-site impacts, through retention and capture of soil and
nutrients in the farm, and off-site impacts, by impeding downslope water
flow. East-African hillslope farms are often cultivated under
slow-forming terraces (Kagabo et al., 2013), where soil eroded up the
plot congregates at the plot boundary, thereby reducing hillslope
gradient. Downslope catchment measures include the use of check dams or
other flow retardants in gullies and incised channels to slow down the
water discharge response to the drainage network, recue channel incision
and stimulate sediment deposition. These offer win-win outcomes of
landscape restoration and enhanced resilience to future climate threats
such as extreme rainfall and drought. Successful implementation of these
multi-scalar intervention opportunities can only be realised with a
thorough and nuanced understanding of community-specific needs and
priorities, as well as wider political and economic contexts, all set
within a deep understanding of landscape hydrological processes and
concepts in both `structural' and `process' connectivity (Bracken et
al., 2013). In brief, the term `structural connectivity' has been used
to describe the distribution of landscape units and features e.g.
topographic controlled, flow convergence lines, gully or track networks
that physically facilitate water and sediment transfers from hillslope
to channel. Structural connectivity approaches are limited to supporting
inferences of potential hydrological connectivity should overland flow
be generated. In this regard, the concept of `process connectivity' has
greater relevance to tackling overland flow generation and soil erosion
by water. This concept encompasses the actual processes that operate to
produce fluxes of water and sediment and capture the evolutionary
dynamics of how hydrological systems function (Bracken et al., 2013).
For example, soil crusting reduces infiltration capacity leading to
infiltration excess overland flow which converges to form and feed rill
and gully network structures. The concept refers to the activation of
the potential pathways described within a structural connectivity
framework, which is generally highly temporally discrete. To date,
however, process and functional connectivity concepts in hydrology have
not directly accounted for the human dimension in land management
decision making an impact of soil hydrology nor the maturity of land
conversion features that might over time increase soil retention
efficacy. Furthermore, in the East African context, connectivity within
hillslopes and river basins is dynamic in both space and time (Wynants
et al., 2020) with marked changes in connectivity due to rainfall
variations, river networks, rapid land use change and positive feedback
of gully incision and channel network expansion over decadal scales -
hydro-geomorphic processes that are still not well understood or
quantified.

The complex spatial and temporal dynamics of overland flow, soil erosion
and sediment conveyance downstream can be better understood by the
scientific community within the framework of hydrological connectivity.
However, stakeholders also have context-specific local in-depth
knowledge of landscape processes, albeit generally through an
agro-pastoral practitioner lens that encompasses social and economic
facets (Wynants et al. 2019). As such, integrating scientific findings
into locally led land management plans presents a challenge/barrier to
research impact. Co-design of land management policy which integrates
local socio-economic and environmental knowledge and is tailored to the
needs of specific communities is a credible pathway to sustainable
change.

Participatory research in this context aims to evaluate not only the key
environmental challenges affecting communities but also, and more
critically, to understand the socio-ecological connectivity (Berkes et
al., 2000) between these environmental challenges and their integration
in socio-economic processes at multiple spatial levels and temporal
scales. Prior work has shown that understanding the linkages is vital to
enable sustainable and equitable change and break the cycle of declining
resilience to soil erosion (Pretty, 1995). In this East African context,
soil erosion is a civic as well as a practical problem. Roads, trackways
and community spaces are all exposed soil surfaces and thus the problem
is not limited to those engaged in agriculture alone; it is a challenge
for the whole community. From this perspective, every community member
has a stake in contributing to the effort to find sustainable solutions;
and every community member has an opportunity to take action to effect
real and lasting change. Co-designing mitigation strategies with
communities ensures that potential solutions are relevant, applicable
and achievable, particularly where alternative livelihood strategies to
support pathways to sustained change are applied. This is exemplified by
Reed et al.'s `bottom-up' participatory principles (Reed et al., 2017)
where community-led planning is guided by the local ambitions of
stakeholders alongside the strategic objectives of external agencies and
state authorities, leading to equitable solutions with much wider
community `buy-in' than those designed through top-down and
non-participatory mechanisms (Pretty, 2003).

\emph{1.3 Aim}

This contribution demonstrates how an established interdisciplinary
participatory approach (Figure 1) supported community-led change in land
management in an East African agro-pastoral community. It explores how
integration of drone survey data and geospatial analysis of erosion
extent and risk, supported by communication of `process' and
`structural' hydrological connectivity, with community participation
successfully underpinned and catalysed a community-led tree planting and
grass seed sowing programme to mitigate soil erosion by water.

\textless{}\textless{} INSERT FIGURE 1\textgreater{}\textgreater{}

Figure 1: Interdisciplinary approach to linking evidence into action
(Blake et al., 2018)

\textbf{2. Materials and methods}

\emph{2.1 Study area: Emaerete sub-catchment}

The study site (Figure 1) is located in the Monduli Highland area, east
of the Northern Tanzanian Rift Valley, with an elevation ranging between
1746m and 2037m. The geology is from volcanic origin and the soils have
evolved to loamy clay andosols on the upper slopes, and to the typical
swelling clay vertisols in the lower topographic swales. The mean annual
rainfall (MAR) ranges from 800 mm in the lower areas to 860 mm for the
higher areas and was obtained from the global ``CHELSA'' dataset (Karger
et al., 2017). The area has a typical bimodal wet season, with a short
peak that occurs from November to December and a long peak between
February and May, and one long dry season from June to October (Prins \&
Loth, 1988). Local and global climatic phenomena such as the El Nino
Southern Oscillation and the Indian Ocean Dipole interlink to create a
high interannual variation wherein the short rains can fail (droughts)
or connect to the long rains (wet) (Nicholson, 1996). The natural
vegetation is mostly an elevation-defined transition between savanna
bushland and afro-montane rainforest. The landscape in many areas is
characterized by severe surface denudation in open grazing land with
notable rill and gully erosion by overland flow (Figure 1b).

The communities are predominantly Maasai and have a long history of
assimilation and reciprocal influencing with other ethnic groups such as
the waArusha and waMeru. Livelihoods in these communities continue to
transition from nomadic pastoralism to sedentary agro-pastoralism driven
by factors such as population growth, social and environmental human
displacement. While traditional customs have gradually lost importance,
they still exist, sometimes assimilated within local governance
structures, or in parallel with formal governance. Much village land is
still set aside for communal grazing, however, during transition to
agro-pastoralism, large areas of land have been entrained into different
ownership processes, and used for mixed agriculture. The rights to these
lands mostly belong to the `original' Maasai people although some of
these plots are also being leased to farmers from other regions in
Tanzania who pay for their tenure in crop-shares. Both processes have
resulted in a conversion of semi-natural grazing lands to cropland. The
dominant cropping system is intercropping of maize with common beans.
However, there are other crops grown in the area such as wheat and
horticultural products. These croplands areas are mostly located in the
upper slopes of the landscape, while the grazing lands are mostly
located in the lower areas and topographic swales.

\textless{}\textless{} Insert Figure 2 \textgreater{}\textgreater{}

Figure 2: Emaerete catchment (a) broad land cover and (b) topography
showing areas designated for agriculture (grey outline) where remainder
is open land utilized for common grazing. Note areas of severe gully
erosion and surface denudation.

\emph{2.2 Drone survey and geospatial analysis}

To develop a topographic digital surface model (DSM) of the study area
using photogrammetry, a drone photographic survey was undertaken using a
Phantom Potensic T25 drone equipped with internal GPS and a 1080p GPS
digital RGB camera with an optimized 120\selectlanguage{ngerman}° wide-angle lens. The
flightpath was set to take photographs from an altitude of 400m, reduced
to 150 m over hill top areas that were obscured by cloud cover. The
flightpath was set so that images had greater than 65\% overlap. Twelve
ground-based GPS reference points were made along the boundaries of the
designated area to permit vertical alignment of relative elevations
derived from the drone survey. A Digital Elevation Model (DEM) was
created using photogrammetric routines within Agisoft Metashape whereby
building and tree interference was removed from the DSM by excluding
points that had a steep (\textgreater{}80°) angle with adjacent point.

The red, green and blue bands of a compile orthomosaic~aerial image of
the study area~were~used as the input for a maximum likelihood
classification using~the QGIS 3.4 saga tool Supervised Classification
for Grids'. Training data were generated through heads up digitisation
of that aerial photograph.~The output of this process
successfully~differentiated gullies and rills from other forms of ground
cover but could not distinguish between~the different vegetation
communities present within the catchment. This high-resolution mapping
of soil erosion features was therefore supplemented with a
conventional~aerial photograph interpretation exercise carried out at a
scale of 1:3000.~In addition to the classification of broad land cover
types within the study area, cultivated land use was subject to a
further level of classification according to the direction of
cultivation. This categorisation was undertaken as a simple aerial image
interpretation (at a scale 1:500) with discontinuities in land
management practices being recorded as separate features (land parcels)
within the GIS layer.

The 1m DEM of the site was analysed in QGIS 3.10 to produce a model of
potential surface flow, slope aspect and slope degree. In order to
simplify subsequent analyses, the aspect of each 1m pixel within the
elevation model were categorised into one of the 8 cardinal directions
(N, NE, E, SE, S, SW, W, NW) These DEM derivatives were used as inputs
in the following analyses. Mean slope degree and modal aspect were
calculated for each parcel of cultivated land identified in the aerial
photograph interpretation using QGis's Zonal statistics tool. The
direction of cultivation recorded in the aerial imagery interpretation
was then compared with the modal aspect for each land use parcel and the
relationship between the two described using these qualitative classes:
cultivation along contours, cultivation with slope and intermediate
cultivation -- where the direction of cultivation had no strong
relationship the aspect of the field. The modelled surface flow was used
for two purposes, firstly to create a Strahler ordered model of
potential overland flow convergence within the study area, and secondly
to select those bare ground (interpreted as eroded) pixels within the
landscape that were probably generated by surface flow i.e. rills and
gully features (in the main visible in high resolution photography). The
selected pixels were then converted into point data and their density
expressed as area (m\textsuperscript{2}) per
m\textsuperscript{2}calculated to derive an independent index of
observed erosion feature density.

\emph{2.3 Community consultation and engagement}

The village level is spatially the lowest statutory administrative unit
in Tanzania and as such, provides two key advantages for our
participatory research approach. First; at this level, local
environmental knowledge and understanding of farm-specific soil
condition, water run-off and seasonal micro-climate is the most finely
nuanced and second; planning and implementation of potential
institutional and community responses has the highest chance of success
because those directly affected by the problems are also directly
engaged in designing workable solutions (Blake et al. 2018). Previous
co-design work with these communities has shown that strong
participatory engagement and knowledge exchange has delivered better
understanding of the impact of social, cultural and economic drivers on
soil management challenges. This approach underpins the model of
engagement discussed in this paper. Participatory approaches enable
affected stakeholders to jointly define the scale and nature of the
problem, find common ground in determining impacts and identify relevant
policy mechanisms and levers for reform. Our previous research has
demonstrated that good soil management is needed which necessitates
farmers and land managers to be empowered to continue to innovate
towards sustainable resource conservation. The ambition of participatory
research is to catalyse the development of a culture of mutual
understanding of potentially competing interests, and willingness to
support honest and open dialogue built around shared understanding of
the socio-economic and well as the hydrological connectivity of the
landscape (Brown, 2002; Moore and Westley, 2011).

Building on previous participatory research carried out with Emaerete
community, a workshop was designed to bring the co-produced set of
visual materials and associated results back to the community and to use
them as a mechanism to explore key elements of local hydrological,
biological and socio-economic connectivity in generating soil erosion
issues. The workshop was held in Emaerete community, attended by twenty
participants from the community and five district government personnel
who were further consulted on workshop outcomes. All discussions were
conducted in Swahili, with facilitation by Tanzanian members of the
research team, and with concurrent translation for English-speaking team
members. Discussions were audio recorded, subsequently transcribed and
translated into English.

Following a brief introduction on the format of the workshop and the
collaborative research activities to be completed, work was structured
into two elements:

\begin{enumerate}
\tightlist
\item
  A short `report back' and review session providing feedback on the
  wider `Jali Ardhi' project research findings to date, (Blake et al.,
  2018; Rabinovich et al., 2019; Wynants et al., 2020, 2018) and team
  learning from community experiences regarding erosion mitigation
  measures taken to date. Measures included demarcated livestock
  exclusion zones for gully rehabilitation; and community commitments to
  plant trees and shrubs; reduce vegetation cutting and change livestock
  grazing patterns.
\item
  Introduction and discussion of the drone survey aerial photo mosaic
  (one A0 scale copy for group discussion) and A2 scale copies for ease
  of handling be individual participants); an infographic tool
  highlighting soil erosion processes; and a set of previously produced
  local erosion impact photographs.
\end{enumerate}

These visual tools were used by both the research team and participants
in multiple ways to illuminate discussion points and trace hydrological
connectivity within the landscape. Using visual methods such as
photographs and the DEM model has the distinct advantage of creating a
shared frame of reference and intuitive understanding despite the
complex and abstract nature of the information. Visual methods using
photographs and images are particularly helpful in supporting a process
of joint learning, negotiation and reflection, around which soil erosion
issues and associated connectivity can be identified. Image-elicitation
is based on the use of one or a series of photographs or other images in
a participatory research context, in order to reach a deeper
understanding of something (Harper, 2002). Image-elicitation can
stimulate empathetic understanding and draw out connections that might
not otherwise be made. In this multi-stakeholder context, discussion
alone faces the challenge of creating a trusting environment between
participants from widely differing backgrounds and philosophical
standpoints, and there is a need to `bridge the gap'. Image-elicitation
techniques can overcome these differences by offering a shared frame of
reference (a composite image of the wider context, or of a particular
issue, for example) on which to build trust and through which deeper
insights can emerge than would otherwise be achieved through discussion
alone (Collier and Collier, 1986).

\textbf{3. Results}

\emph{3.1 Topography and land cover}

Derived land cover classes (Figure 3a) were broadly spread across
cultivated plots (26\%), open pastoral land (30\%) including homestead
farm areas with sporadic tree and shrub cover and exposed soil surfaces
in and around village buildings. Areas with patchy grass and rough shrub
cover, often with intermittent soil loss and vegetation disturbance due
to erosion, were classed as scrub (10\%). Areas of notable bare ground
were observed in the severely eroded mid to lower slope region (Figure
4) that receives much of the concentrated overland flow from the
hillslopes above.

\textless{}\textless{} INSERT FIGURE 3 \textgreater{}\textgreater{}

Figure 3: (a) land cover classification and (b) derived mean slope for
cultivated plots

\textless{}\textless{} Insert Figure 4 \textgreater{}\textgreater{}

Figure 4: Severely degraded pastoral land in the mid to lower region of
the catchment (photos Carey Marks/University of Plymouth, taken March
2017)

The cultivated plots occupied the east and southeastern side of the
catchment upland zone and hence represent potential overland flow
contribution areas to the mid and lower slope gullied zones. The group
of cultivated plots to the east of the system are the most recently
converted (from open grazing to cultivation) land (ca 1-3 years prior to
survey) with boundaries set to shallow ditches and bunds akin to
`slow-forming' terrace approaches (Chapagain and Raizada, 2017; Dercon
et al., 2003). Vegetation along these boundaries was largely immature
grasses. The cultivated plots to the south were more established (over 7
years) with notable establishment of edge-of-plot bunds and mature
vegetation along boundaries. In both areas of cultivation, uppermost
plots showed steeper slopes (Figure 3b) graduating to more gentle slopes
toward and on the open pastoral land.

The cultivated land plots are interconnected with unmetalled trackways
commonly used to drive livestock and for pedestrian and motorbike
access. All tracks are incised to varying degrees with notable incision
on downslope reaches of tracks from upper cultivated plots. Severe
erosion of pastoral land originates from apparent overland flow spill
over and concentration from track in centre west of the study area
(Figure 3b). Severe gully erosion has resulted in upslope relocation of
the track on more than one occasion.

\emph{3.2 Structural connectivity framework and observed erosion}

Comparison of potential flow pathways (grey convergence lines, Figure 5)
and observed density of rills (white-grey-black shaded plots in Figure
5) reveal a disconnect in potential and actual development of rill
erosion in some plots. Plots coloured white have a low
(\textless{}0.0005 m\textsuperscript{2} m\textsuperscript{-2}) density
of rill features observed in the drone survey and there are several
notable examples where the topography-driven model predicts flow
convergence but no rill erosion features were observed (e.g.
northeastern sector, labelled A, Figure 5). Equally, however, there are
plots where topography predicts flow convergence which correlated with
observations of high-density rill erosion (\textgreater{} 0.007
m\textsuperscript{2} m\textsuperscript{-2}) (e.g. south eastern sector,
area B, Figure 5). Herein there is a notable strip plot showing no
erosion features that had apparently been cultivated shortly before the
drone survey (see Figure 2a) highlighting potential limitation in the
approach with respect to cultivation duration and timing prior to
survey. Area C is notable again for lack of erosion features given
potential convergence line density wherein these fields also have
limited potential for overland flow run-on given track along upper
slope. These areas can be compared to area E in the open pastoral land
where severe erosion was observed, linked to overspill from the track
(Figure 4). In comparison to area B, cultivated area D is notable for
lack of erosion features given potential for higher order flow
convergence routing wherein observational evidence of crop growth
indicates potential rill features have not been cultivated out in this
instance. It is also noteworthy that the area upslope of these plots
remain under semi-natural vegetation cover compared to area B and that
there is no major difference between area D and B in terms of slope
angles (Figure 3b). In the more recently converted plots of area B, ca
90\% of the area with potential for flow convergence showed moderate or
high density of rill erosion features. In area D, the established
agricultural plots, ca 40\% of the area with potential for flow
convergence showed moderate rill erosion density.

\textless{}\textless{} INSERT FIGURE 5\textgreater{}\textgreater{}

Figure 5: \emph{Potential} overland flow convergence pathways, major
trackways and summary first order \emph{observed} rill density in
cultivated plots.

\emph{3.2 Process connectivity framework and observed erosion}

In terms of process connectivity overland flow enhancement factors,
on-the-ground measures of soil infiltration capacity and soil
erodibility (aggregate stability) across the different agricultural
plots was beyond the scope of this drone survey-based study. We
hypothesised, however, that at a higher level, correlation of plot
cultivation direction with high density of rill erosion could be
illustrative of cultivation controls on potential overland flow
generation in the context of process connectivity concepts that
encompass impacts on overland flow generation and slope length.

\textless{}\textless{}\textless{} Insert Figure 6
\textgreater{}\textgreater{}\textgreater{}

Figure 6: Aerial photographs of key illustrative zones showing field
boundaries, cropping practice and incidence of rill erosion.

Zones of different time since plot establishment, configuration and
within plot practice showed different degrees of rill density and
network development (Figure 6). In zone B, where the greatest density of
rill erosion was observed, there were two main rill networks (labelled
B1, B2, Figure 7) connecting upper slope to lower and discharging onto
the main track running E-WSW which ultimately spills across the pastoral
land at E. The agricultural plots in B1 are oriented across slope so
boundaries traverse any potential flow lines in accord with local `good
practice' but cultivation lines within the plots are largely in the
direction of slope (indicated by amber and red arrows, Figure 7), with
the exception of the lowermost plots. On top of that, the higher plots
are also developed on very steep slopes (\textgreater{}12°). In zone B2,
again the plots themselves are largely and appropriately orientated
across the slope but within plots, there is a mosaic of cultivation
directions. The rill network on this slope is well developed and crosses
all cultivated plots connecting them to the main track way. It is also
important to note that the slope length on these plots is also longer.

\textless{}\textless{} INSERT FIGURE 7 \textgreater{}\textgreater{}

Figure 7: Comparison of first order rill density data and orientation of
cultivation with respect to slope

Zones A and D contrast with the situation of zone B. Both zones A and D
show more moderate observation of rill density (Figure 6). In zone A,
the plots are contoured around a valley head. Plots to the northern side
have crop lines contoured with plot boundaries (green arrows, Figure 7)
and little evidence of rill erosion. To the southern side, crop lines
show some alignment to slope (amber arrows, Figure 7) and there is
moderate rill erosion in the lower plots (Figure 6). In Zone D, plot
boundaries are more exactly contoured to topography than zone B (Figure
6) and there is only one incidence of cultivation lines being with the
slope, the remainder being intermediate or contoured. Rills in this area
do not display the same level of development and connectivity as zone B.
Zone C offers a different scenario where while cropping lines are
contoured, moderate rill erosion was determined (Figure 7) and
apparently concentrated along plot boundaries before overtopping
edge-of-field bunds (Figure 6). The extensive erosion of gentle to
moderately sloped pastoral land, zone E (Figure 6), occurred at the
outlet of the track fed by extensive rill erosion in zone B with some
contribution from zone C.

\emph{3.4 Infographic tool for dissemination of connectivity concepts}

To support dissemination of connectivity concepts an infographic tool
(Figure 8) was developed based on a generic narrative of the
consequences of land conversion/grazing on soil vegetative cover and
soil surface degradation. The centre part of the infographic focusses on
reduced infiltration due to soil exposure and reduced infiltration
linked to rain splash, aggregate breakdown with loss of soil organic
matter and surface crusting. The wider narrative of the poster was
designed to set the landscape in context, showing the destructive
narrative of the erosion unfolding from the top, to the bottom of the
image. The tracks and pathways dissect the landscape, showing livestock
and human traffic aggravating the initial stream channel incisions --
and the structural connectivity, linking the upslope disturbance to
downslope challenges -- and inevitable result of enhanced overland flow.

We chose to create a visual style that would resonate culturally both
within the Western and sub-Saharan diaspora. By developing a series of
graphic devices, recognisable local iconography, a bright colour
palette, and lastly an abstraction of reducing the three-dimensional
scenario into a two-dimensional illustration -- the attempted result was
to create an eye-catching and visually pleasing poster that encouraged
interaction and discussion with the researchers and stakeholders alike.

\textless{}\textless{} INSERT FIGURE 8 \textgreater{}\textgreater{}

Figure 8: Infographic poster designed to explain structural and process
connectivity concepts (see text for explanation).

\emph{3.4 Local Environmental Knowledge}

The DEM image generated considerable interest amongst participants. The
first step was to orientate the image to local landmarks, to enable
those present to identify their own land on the DEM and situate their
understanding of the real world three-dimensional landscape within the
context of the two dimensional aerial view. Once done, participants used
the infographic tool to begin relating their understanding of water flow
across their own land, and its associated connection to gullying
downslope. This was the first time that local participants could see
`from above' how the complexity of landscape topography played a
critical role in whether specific mitigation actions would have the
planned effect:

\emph{VLG1: In order to fill gullies and look as what we see from the
map, we have to plant grasses as it looks down there. This erosion
occurs because when the rainwater flows from the upslope it lacks
barriers which protect soil from being washed away. So now as the water
flows downslope it erodes soil and leave cracks on land surface. All we
have to do is plant grasses and trees.}

Although initial discussions centred primarily on how hydrological
processes had created rapid overland flow leading to severe erosion and
gullying downslope; the focus rapidly shifted towards the physical
drivers (lack of effective terracing in upland farms to slow overland
flow; lack of trees and vegetation upslope) and associated
socio-economic drivers (lack of conservation agriculture knowledge,
skills or resources; lack of compliance) as this participant notes:

\emph{VLG8: Some of people living uphill there haven't terraced their
farms and when it rains water flows through their farms till down
here.Facilitator: Why is it that some haven't terraced their farms. Have
they not been told or it's just that they don't want?} \emph{VLG4: It's
because of ignorance because everyone has got their own knowledge and
understanding. You can find someone lacks even the basic knowledge of
doing something in order to prevent soil erosion.}

Further discussion highlighted a particular issue on land outside of
private ownership, where less effort was made on soil erosion
mitigation, and where water was directed towards, to avoid eroding
private land. This resulted in faster flow along cattle trackways and
paths which were located on common areas. In order to deal with this
specific issue, participants identified areas on the map which could be
zoned as priority areas to plant trees and shrubs in order to mitigate
and slow hydrological flow. The DEM played a critical role in enabling
participants to identify the areas for actions likely to have most
impact in slowing flow based on their overview of the topography; and
supported a much more focussed debate regarding the specific actions
(tree-planting; terracing; education) needed to suit the differing soil
types in each area:

\emph{VLG6: First of all, the places you see are fields that people grow
crops. Although people farm, there is a difference in soil between one
zone and another. Where you see there is erosion is the newly cultivated
farming area and the other side which is uneroded it's uncultivated
area. And areas you see as eroded are cultivated areas. Erosion takes
place downstream there. But what causes erosion downstream is the
difference in soil between down here and up there. Therefore, as water
flows from upstream it doesn't erode as it does down here.}

Using the DEM, participants also reflected on the relative success of
the demonstration plots set up with the community during the original
Jali Ardhi project. These areas highlighted the close coupling between
institutional factors, such as the commitment of village leadership to
maintain these areas as livestock exclusion zones. As a result of that
commitment, gullies in the excluded zones had begun to show significant
vegetation growth, with the resulting reduction in hydrological flow
across this lower-level topography, as this participant noted:

\emph{VLG2: Another lesson, you might for example set aside an area for
3 years without livestock getting in. {[}\ldots{}{]} For example, down
there you can see we have set an area and prevent cattle from getting in
and we have seen changes as gullies are now filling up. The best
practice therefore is to set an area and leave it for a while without
allowing cattle in so as to allow grasses grow and reduce speed of water
flow.}

The community-led outcome of this workshop was a commitment to deliver a
tree and shrub planting programme, with specific species and planting
locations selected by community members. In order to facilitate this
next step, a community tree committee was set up, led by the Village
Leader, with externally-provided practical training and support in
planting techniques and ongoing maintenance. This programme was
delivered during the short rainy season in December 2019 to allow the
trees to use rain for survival.

\textbf{4. Discussion}

\emph{4.1 Translating people-land-water connectivity evidence into
targeted mitigation actions}

The modelled flow lines between different catchment areas map indicate
direct hydrological connection between severely eroded pastoral land in
the mid and lower slope regions of the catchment (Figure 6e) with
upslope runoff generation on cultivated plots. Connectivity is enhanced
through interconnection of major tracks with natural flow convergence
lines, where downslope gully onset was often initiated directly below
road channels entering the rangelands (exemplified again in Figure 6e).
The whole catchment view of this study is critical in underpinning
community-led action. These observations also have important
implications for track management and planning of runoff drains that can
release water and eroded sediment and nutrients back into the fields.

Within plot improvements in soil infiltration capacity to reduce
overland flow generation (Kuyah et al., 2019; Nishigaki et al., 2017) is
key as is improvement of and aggregate stability, e.g. with amendment by
organic matter, to reduce risk of soil capping/crusting (Laker and
Nortjé, 2019; Smith et al., 2019) and improve overall soil health
(Belayneh et al., 2019; Mesfin et al., 2018). While such within-plot
actions can be locally beneficial, analysis in this study has shown that
different agricultural plot terraces on the same slope are chained to
each other. At the edge of plots, implementation or augmentation of
features that can attenuate or slow overland flow to retain soil within
the plots are important but poor practice upslope, however, can generate
significant overland flow that overwhelms the integrity of downslope
plot terraces, even if the latter uses conservation agriculture
practices that promote infiltration and good soil health. Herein slope
length is a key factor (Gourfi et al., 2018). This is exemplified in
zone B1 and B2 where slope length was high (\textless{} 800 m) and the
relatively recent conversion of the land with under-developed boundaries
meant that attenuation features could not cope with the amounts of
overland flow generated. This allowed an extensive and well-connected
rill network to develop and link all plots to each other and the main
track (Figure 6b). This was augmented by a large proportion of plots
cultivating crop rows in the direction of slope even though the plots
themselves, and their boundaries, were aligned across the slope.
Off-contour cropping is widely known to enhance rill development (Ayele
et al., 2018). In contrast, visual evidence of rilling was markedly
lower in the longer established plots (e.g. zone D) where farmers have
used contour ploughing and the plot boundaries themselves are more
closely aligned with contours. While the upper slope angle is still
high, the hilltop steep land has been left in natural vegetation both
reducing run-on from the upslope contributing area and effectively
reducing the overall length of the slope segment. With the longer-term
establishment of plot boundaries there is further resilience to
development on connected rill networks due to edge-of-plot barriers that
are not overwhelmed by any overland flow that does occur under extreme
rainfall conditions. The strong influence of the direction of crop lines
is further exemplified by comparison of the two valley sides of Zone A
(Figure 6a).

Comparison of the longer-established cultivated plots and recently
converted land in this study highlights a problem in the initial phase
of slow-forming terraces, as not enough time has passed for the buffers
to become effective in stopping flow and the slope gradients to
decrease, giving almost free reign to erosive processes. The community
picked up the key issue of plot boundary integrity and flow retardation
by natural vegetation, wherein suggestions of planting trees and
permanent grasses were made. The integration of people, land and water
into one connectivity framework exposed a direct chain of cause and
effect that can promote cooperative community-led mitigation to stop the
downstream propagation of runoff. This is potentially facilitated by the
agro-pastoral structure of the community, wherein farmers are both
dependent on cropland and on the rangelands for livestock grazing,
presenting an opportunity for integrated catchment management.

\emph{4.2 Catalyzing local governance decisions to increase landscape
resilience to erosion}

The DEM and orthomosaic aerial photograph provided a unique
visualisation of the landscape connectivity for community members who
have little formal scientific training and normally have no access to
satellite imagery. One of the central aspects underpinning the workshop
discussion of hydrological connectivity on the ground was an implicit
understanding of the need for effective governance mechanisms (including
policy instruments) at both community and District levels, to enable
community-led actions to be implemented effectively and, more
importantly, consistently. Herein a key incentive (German, 2018) being
retention of soil and nutrients within the plot and reducing collective
impact on downslope common land. Two specific governance elements were
identified by participants: Committed leadership supported by the
majority of the community; and effective sanctions for policy
non-compliance. Previous co-designed community actions (Blake et al.,
2018; Rabinovich et al., 2019) included setting aside (and fencing
against livestock) an area of severely eroded and gullied communal
grazing land, as a demonstration plot to trial potential erosion
mitigation and rehabilitation solutions. The demonstration plot had been
established for three years and had been significantly expanded by the
community without further external support or materials. The
effectiveness of this area at slowing water and the speed of
revegetation was frequently commented on during the workshop.
Critically, the success of these plots (Figure 9) was recognised as
being largely a reflection not of their physical design but of the
quality of governance processes within this specific community. Despite
severe pressure for grazing land, community members (including those who
were not directly involved in the previous projects) were prepared to
respect the Village Leader's decision to exclude grazing in this area
notwithstanding the resulting personal economic costs (loss of grazing).
Success rested on short term gain for a small number of community
members being deferred for longer-term gain for the wider community.

The connection between good governance mechanisms and mitigation
measures to slow water in high risk areas reflects the temporal and
spatial challenges of taking proximal actions to achieve distal benefits
(Wynants et al., 2019). Land management actions need to be taken upslope
and regularly maintained, at cost to individual land owners and users,
but the benefits are largely experienced downslope and across relatively
longer timeframes. Despite these challenges, this research demonstrates
that using images and other visual tools supports communities to
visualise actions, and associated changes in three dimensions; and
facilitates abstraction of impacts beyond individual costs, to reveal
wider societal benefits.

\textless{}\textless{}\textless{} INSERT FIGURE 9
\textgreater{}\textgreater{}\textgreater{}

Figure 9: evidence of recovery following livestock exclusion (comparing
March 2017 and November 2019)

\textbf{5. Conclusion}

While soil erosion processes are complex and multifaceted, co-design of
land management policy tailored to the needs of specific communities can
be achieved through participatory engagement where scientists and the
community work together to identify evidence of the problem, evaluate
the drivers and share knowledge to inform actions. This contribution
demonstrates how communication of land degradation process knowledge,
through an established interdisciplinary participatory approach has
supported community-led change in land management in an East African
agro-pastoral community. High resolution aerial photography coupled with
flow connectivity modelling and geospatial analysis demonstrated the
importance of upslope overland flow generation and routing from recently
converted cultivated land to downslope grazing land where severe erosion
is observed and formerly believed to be wholly caused by overgrazing.
Herein community adaptability that is needed to cope with the challenges
brought by dynamic people-land-water connectivity can be undermined by a
lack of ability to respond due to a lack of `slack' in their systems
caused by erosion of their resources and their options. This study
demonstrates that such barriers can be overcome wherein impact from
research evidence bases was realized though a knowledge exchange
workshop with community leaders, livestock owners, farmers and District
Council officials. Key outcomes were the formation of a tree planting
committee, implementation of a targeted planting programme of 200 trees
and shrubs in hydrologically vulnerably hot spots, new grazing
management regimes and commitment to a longer-term community land
management plan. The study demonstrates the critical importance of
integrated upstream/upslope and downstream/downslope thinking when
tackling complex soil erosion challenges.

\textbf{Acknowledgements:}

The research team are indebted to the commitment and warm support of the
community in Emaerete village. The research was supported by Research
England `QR' Global Challenges Research Funds allocated by the
University of Plymouth {[}\emph{Ardhi na Kujifunza (Land and Learning}
{]} building on UK Natural Environment Research Council Grant
NE/R009309/1 and Research Council UK Global Challenges Research Fund
(GCRF) grant NE/P015603/1. The study represents a contribution to the
joint UN FAO/IAEA Coordinated Research Projects (CRP) ``\emph{D15017:
Nuclear Techniques for a Better Understanding of the Impact of Climate
Change on Soil Erosion in Upland Agro-ecosystems} '' and
``\emph{D1.50.18: 'Multiple Isotope Fingerprints to Identify Sources and
Transport of Agro- Contaminants'} ''.

\textbf{Conflict of Interest Statement}

The authors have no conflict of interest to declare.

\textbf{Statement of contribution of authors}

All authors are active contributors to intellectual content. The
manuscript concept was conceived by WB who led the drafting of the
manuscript and analysis and interpretation of data. CK led the
acquisition and interpretation of the social science data and
contributed to the structure and drafting of the manuscript. MW
contributed analysis and interpretation of geospatial data, and
structure and drafting of the manuscript. AP co-led acquisition of
social science data and contributed to socio-cultural interpretations
and drafting of the manuscript. SL designed and undertook specialist
geospatial data analysis, interpretation and visualization and drafting
of the manuscript. JL, EN and AP made substantial contributions to
acquisition of data through drone survey design and implementation plus
data interpretation within post-processing of DEM. MN contributed
intellectual design of stakeholder engagement process to acquire social
science data. CM conceived and delivered infographic design and
intellectual integration with science mission. DG, KM, LM and PN
contributed to drafting through critical revision of manuscript
intellectual content.

\textbf{REFERENCES}

Ayele, G.K., Addisie, M.B., Langendoen, E.J., Tegegne, N.H., Tilahun,
S.A., Moges, M.A., Nicholson, C.F., Steenhuis, T.S., 2018. Evaluating
erosion control practices in an actively gullying watershed in the
highlands of Ethiopia. Earth Surf. Process. Landforms 43, 2835--2843.
https://doi.org/10.1002/esp.4436

Belayneh, M., Yirgu, T., Tsegaye, D., 2019. Effects of soil and water
conservation practices on soil physicochemical~properties in Gumara
watershed, Upper Blue Nile Basin, Ethiopia. Ecol. Process. 8.
https://doi.org/10.1186/s13717-019-0188-2

Berkes, F., Folke, C., Colding, J., 2000. Linking social and ecological
systems: management practices and social mechanisms for building
resilience vol 1.

Blake, W., Rabinovich, A., Wynants, M., Kelly, C., Nasseri, M., Ngondya,
I., Patrick, A., Mtei, K., Munishi, L., Boeckx, P., Navas, A., Smith,
H., Gilvear, D., Wilson, G., Roberts, N., Ndakidemi, P., 2018. Soil
erosion in East Africa: an interdisciplinary approach to realising
pastoral land management change. Environ. Res. Lett.
https://doi.org/10.1088/1748-9326/aaea8b

Bracken, L.J., Wainwright, J., Ali, G.A., Tetzlaff, D., Smith, M.W.,
Reaney, S.M., Roy, A.G., 2013. Concepts of hydrological connectivity:
Research approaches, pathways and future agendas. Earth-Science Rev.
119, 17--34. https://doi.org/10.1016/j.earscirev.2013.02.001

Brown, K., 2002. Innovations for conservation and development. Geogr. J.
168, 6--17. https://doi.org/10.1111/1475-4959.00034

Chapagain, T., Raizada, M.N., 2017. Agronomic Challenges and
Opportunities for Smallholder Terrace Agriculture in Developing
Countries. Front. Plant Sci. 8, 331.
https://doi.org/10.3389/fpls.2017.00331

Cobo, J.G., Dercon, G., Cadisch, G., 2010. Nutrient balances in African
land use systems across different spatial scales: A review of
approaches, challenges and progress. Agric. Ecosyst. Environ.
https://doi.org/10.1016/j.agee.2009.11.006

Collier, J.J., Collier, M., 1986. Visual anthropology: Photography as a
research method (revised and expanded edition). University of New Mexico
Press.

Dercon, G., Deckers, J., Govers, G., Poesen, J., Sánchez, H., Vanegas,
R., Ramírez, M., Loaiza, G., 2003. Spatial variability in soil
properties on slow-forming terraces in the Andes region of Ecuador. Soil
Tillage Res. 72, 31--41. https://doi.org/10.1016/S0167-1987(03)00049-7

FAO, 2019. Let's \#StopSoilErosion to ensure a food secure future
\textbar{} FAO Stories \textbar{} Food and Agriculture Organization of
the United Nations {[}WWW Document{]}. URL
http://www.fao.org/fao-stories/article/en/c/1192794/ (accessed 3.23.20).

German, L., 2018. Catalyzing self-governance: Addressing multi-faceted
collective action dilemmas in densely settled agrarian landscapes. Int.
J. Commons 12, 217--250. https://doi.org/10.18352/ijc.852

Gourfi, A., Daoudi, L., Shi, Z., 2018. The assessment of soil erosion
risk, sediment yield and their controlling factors on a large scale:
Example of Morocco. J. African Earth Sci. 147, 281--299.
https://doi.org/10.1016/j.jafrearsci.2018.06.028

Harper, D., 2002. Talking about pictures: A case for photo elicitation.
Vis. Stud. 17, 13--26. https://doi.org/10.1080/14725860220137345

Hiemstra-van der Horst, G., Hovorka, A.J., 2009. Fuelwood: The ``other''
renewable energy source for Africa? Biomass and Bioenergy 33,
1605--1616. https://doi.org/10.1016/j.biombioe.2009.08.007

Homewood, K., Coast, E., Thompson, M., 2004. In-Migrants and Exclusion
in East African Rangelands: Access, Tenure and Conflict. Africa (Lond).
74, 567--610. https://doi.org/10.3366/afr.2004.74.4.567

International Institute of Rural Reconstruction., African Conservation
Tillage Network., 2005. Conservation agriculture\selectlanguage{english} : a manual for farmers
and extension workers in Africa. International Institute of Rural
Reconstruction.

Jayne, T.S., Chamberlin, J., Headey, D.D., 2014. Land pressures, the
evolution of farming systems, and development strategies in Africa: A
synthesis. Food Policy 48, 1--17.
https://doi.org/10.1016/j.foodpol.2014.05.014

Kagabo, D.M., Stroosnijder, L., Visser, S.M., Moore, D., 2013. Soil
erosion, soil fertility and crop yield on slow-forming terraces in the
highlands of Buberuka, Rwanda. Soil Tillage Res. 128, 23--29.
https://doi.org/10.1016/j.still.2012.11.002

Kassam, A., Friedrich, T., Derpsch, R., 2019. Global spread of
Conservation Agriculture. Int. J. Environ. Stud. 76, 29--51.
https://doi.org/10.1080/00207233.2018.1494927

Korotayev, A., Zinkina, J., 2015. East Africa in the Malthusian Trap? J.
Dev. Soc. 31, 385--420. https://doi.org/10.1177/0169796X15590322

Kuyah, S., Whitney, C.W., Jonsson, M., Sileshi, G.W., Oborn, I.,
Muthuri, C.W., Luedeling, E., 2019. Agroforestry delivers a win-win
solution for ecosystem services in sub-Saharan Africa. A meta-analysis.
Agron. Sustain. Dev. 39. https://doi.org/10.1007/s13593-019-0589-8

Laker, M.C., Nortje, G.P., 2019. Review of existing knowledge on soil
crusting in South Africa, in: Advances in Agronomy. Academic Press Inc.,
pp. 189--242. https://doi.org/10.1016/bs.agron.2019.01.002

Lal, R., 2001. Soil degradation by erosion. L. Degrad. Dev. 12,
519--539. https://doi.org/10.1002/ldr.472

Little, P.D., 1996. Pastoralism, biodiversity, and the shaping of
savanna landscapes in East Africa. Africa (Lond). 66, 37--51.
https://doi.org/10.2307/1161510

Mesfin, S., Taye, G., Desta, Y., Sibhatu, B., Muruts, H., Mohammedbrhan,
M., 2018. Short-term effects of bench terraces on selected soil physical
and chemical properties: landscape improvement for hillside farming in
semi-arid areas of northern Ethiopia. Environ. Earth Sci. 77.
https://doi.org/10.1007/s12665-018-7528-x

Moore, M.L., Westley, F., 2011. Surmountable chasms: Networks and social
innovation for resilient systems. Ecol. Soc. 16.
https://doi.org/10.5751/ES-03812-160105

Nearing, M., Pruski, F.F., O'Neal, M.R., 2004. Expected climate change
impacts on soil erosion rates: A review. J. Soil Water Conserv. 59.

Ngecu, W.M., Mathu, E.M., 1999. The El-Nino-triggered landslides and
their socioeconomic impact on Kenya. Environ. Geol. 38, 277--284.
https://doi.org/10.1007/s002540050425

Nishigaki, T., Sugihara, S., Kilasara, M., Funakawa, S., 2017. Surface
Runoff Generation and Soil Loss Under Different Soil and Rainfall
Properties in The Uluguru Mountains, Tanzania. L. Degrad. Dev. 28,
283--293. https://doi.org/10.1002/ldr.2499

Odgaard, R., 2002. Scrambling for land in Tanzania: Process of
formalisation and legitimisation of land rights. Eur. J. Dev. Res. 14,
71--88. https://doi.org/10.1080/714000434

Oldeman, L.R., 1991. Global Extent of Soil Degradation, ISRIC Bi-Annual
Report.

Pretty, J., 2003. Social Capital and the Collective Management of
Resources. Science (80-. ). https://doi.org/10.1126/science.1090847

Pretty, J.N., 1995. Participatory learning for sustainable agriculture.
World Dev. 23, 1247--1263. https://doi.org/10.1016/0305-750X(95)00046-F

Rabinovich, A., Kelly, C., Wilson, G., Nasseri, M., Ngondya, I.,
Patrick, A., Blake, W.H., Mtei, K., Munishi, L., Ndakidemi, P., 2019.
``We will change whether we want it or not'': Soil erosion in Maasai
land as a social dilemma and a challenge to community resilience. J.
Environ. Psychol. 66. https://doi.org/10.1016/j.jenvp.2019.101365

Reed, M.S., Vella, S., Challies, E., de Vente, J., Frewer, L.,
Hohenwallner-Ries, D., Huber, T., Neumann, R.K., Oughton, E.A., Sidoli
del Ceno, J., van Delden, H., 2017. A theory of participation: What
makes stakeholder and public engagement in environmental management
work? Restor. Ecol. 1--11. https://doi.org/10.1111/rec.12541

Rufino, M.C., Thornton, P.K., Ng'ang'a, S.K., Mutie, I., Jones, P.G.,
van Wijk, M.T., Herrero, M., 2013. Transitions in agro-pastoralist
systems of East Africa: Impacts on food security and poverty. Agric.
Ecosyst. Environ. 179, 215--230.
https://doi.org/10.1016/j.agee.2013.08.019

Ruttan, L.M., Borgerhoff Mulder, M., 1999. Are east African pastoralists
truly conservationists? Curr. Anthropol. 40, 621--652.
https://doi.org/10.1086/300086

Smith, J.D.V., Strauss, J.A., Hardie, A.G., 2019. Effects of long-term
grazed crop and pasture systems under no-till on organic matter
fractions and selected quality parameters of soil in the Overberg, South
Africa. South African J. Plant Soil.
https://doi.org/10.1080/02571862.2019.1640298

Vanmaercke, M., Poesen, J., Broeckx, J., Nyssen, J., 2014. Sediment
yield in Africa. Earth-Science Rev. 136, 350--368.
https://doi.org/10.1016/j.earscirev.2014.06.004

Veldhuis, M.P., Ritchie, M.E., Ogutu, J.O., Morrison, T.A., Beale, C.M.,
Estes, A.B., Mwakilema, W., Ojwang, G.O., Parr, C.L., Probert, J.,
Wargute, P.W., Grant Hopcraft, J.C., Olff, H., 2019. Cross-boundary
human impacts compromise the Serengeti-Mara ecosystem. Science (80-. ).
363, 1424--1428. https://doi.org/10.1126/science.aav0564

Wynants, M., Kelly, C., Mtei, K., Munishi, L., Patrick, A., Rabinovich,
A., Nasseri, M., Gilvear, D., Roberts, N., Boeckx, P., Wilson, G.,
Blake, W.H., Ndakidemi, P., 2019. Drivers of increased soil erosion in
East Africa's agro-pastoral systems: changing interactions between the
social, economic and natural domains. Reg. Environ. Chang.
https://doi.org/10.1007/s10113-019-01520-9

Wynants, M., Millward, G., Patrick, A., Taylor, A., Munishi, L., Mtei,
K., Brendonck, L., Gilvear, D., Boeckx, P., Ndakidemi, P., Blake, W.H.,
2020. Determining tributary sources of increased sedimentation in
East-African Rift Lakes. Sci. Total Environ. 717, 137266.
https://doi.org/10.1016/j.scitotenv.2020.137266

Wynants, M., Solomon, H., Ndakidemi, P., Blake, W.H., 2018. Pinpointing
areas of increased soil erosion risk following land cover change in the
Lake Manyara catchment, Tanzania. Int. J. Appl. Earth Obs. Geoinf. 71,
1--8. https://doi.org/10.1016/j.jag.2018.05.008\selectlanguage{english}
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