RECURRENT LANDSLIDES OF LAGAM ESCARPMENT, KABEN LOCATION, MARAKWET EAST, KENYA

The landslides of the Lagam escarpment, Kaben Location, Marakwet, Elgeyo Marakwet County, are not only recurrent but are highly cataclysmic; causing mayhem whenever they occur. The first known landslides on the Lagam escarpment of Kaben location -Marakwet, happened during the 1961 El-Nino, when a major rainstorm hit the area (Kiptungu). These landslides re-fashioned Embosumer River and left huge boulders scattered over many farmlands. In 2010, a catastrophic landslide hit Kaben location and again, Embosumer River was the perpetrator, having broken its banks due to excessive water inflow. Many lives were lost and lots of property was destroyed. In 2020, heavy rains pounded the area causing massive mudslides that involved many rivers and streams; such as Embosumer, Emboreberwo and Karengor. As a result, twenty-six (26) lives were lost, homes, schools and farmlands were washed away and to date, there are several bodies believed to be trapped in the mudslide material. This study is geared towards investigating the causes of the recurrent landslides and proposing possible mitigation measures. Data was collected through secondary data analysis and has been presented in the form of ground photographs, satellite images and discussions made thereon. It is hoped that this preliminary study of the Lagam escarpment landslides will create awareness pertaining to the recurrent landslides and draw positive action from the area residents and all concerned.


INTRODUCTION
The Lagam escarpment is a section of the larger Elgeyo-Marakwet escarpment (Kerio escarpmant), that traverses Keiyo, Marakwet and West Pokot regions. The steep palisade is the western scarp of the Kerio Valley depression (Kipkiror & Towett, 2013). It is highly rugged, being dissected in many sections, by parallel escarpment rivers and streams. This gives it an appearance of wedged hills separated by sharp Vshaped valleys, which are believed to be fault lines extending from the Kerio fault, in which Kerio River flows. The Lagam escarpment is also high, reaching an altitude of about 3520m Above Sea Level (ASL) at Chemnirot and 3500m ASL at Kamalogon hill. The rivers originate from Embobut forest and mostly flow eastwards, joining River Kerio, which drains into Lake Turkana. The Lagam Escarpment is sparsely vegetated, except for the deteriorating Embobut forest that still has a semblance of a continuous canopy. The vegetation cover on the escarpment and the Embobut forest is thoroughly degraded by escalating human settlement and agriculture in the unfavourably steep and rugged area. Consequently, a large section of the Lagam escarpment is deplorably 'bare'.
The escarpment soils are lateritic in nature, except for the isolated grooves and river valleys where alluvium soil is found. The soil is also highly eroded, owing to the steep nature of the terrain. The Kaben Location section of the escarpment has been hit by landslides more than any other section of the Lagam escarpment and this may have everything to do with the area's geology. The area, right from Embosumer River in Marakwet East to Chemisto and Sonokor areas of West Pokot County (Cheptulel Location), appears to be rocky and the rock seems to be one continuous dark block. This makes the Kerio escarpment of Kaben Location unique. In fact, it appears to be pushed backwards, comparing it to the other sections of the Lagam escarpment, such as Wewo and Katilit sections, which are equally steep but semi stable. According to Mason and Gibson (1957) cited by Nyaberi et al. (2019), the Kerio valley floor (Kew) is alluvium filled and the escarpment has its base in gneiss with an irregular capping of porphyritic phonolite. Some phonolite is often found exposed beneath the gneiss rocks, suggesting uneven lava outpourings during the formation of the Kerio Valley. The gneiss on the escarpment is of the Basement System. There are dark hornblende rocks in several areas of the escarpment. The gneiss (product of metamorphosed granite) appears to be un-weathered across the Lagam escarpment of Kaben location, making it easy for the thin escarpment soils to slide downhill, during heavy precipitation. This is evidenced by the bare rock scars that were left behind by the recent landslides (mudflows)-across the entire location, all the way to Cheptulel Location. In April 2020, heavy rains on the Lagam escarpment of Marakwet East, caused rapid flash floods and mudslides to erupt, both on the Marakwet and Pokot sections of the escarpment. Twenty-six (26) people lost their lives, when Liter and Chesegon areas of Marakwet East and West Pokot, were washed away. Two rivers: Embosumer and Emboreberwo, joined forces to wreak havoc. The two rivers are in Marakwet East but Emboreberwo taps runoff from both the Pokot and Marakwet sections of the Kerio escarpment, to the west. Downstream, they become River Chesegon. The mudslides left massive scars on the escarpment and rock trails, on the river valleys and farmlands from which local residents draw their livelihood. There were some mudslides at Kipchumwa location as well. Cracks have been reported on parts of Katilit and Kipchumwa, indicating that the landslide problem in the Lagam escarpment may not be over and could be spreading to other areas, outside Kaben location. Furthermore, step faulting may have enhanced the landslides in the area. Plate 1 show the step faults that appear to consist of normal faults and the rock that makes up the escarpment can be clearly seen from Plate 1.
Plate 2: Farmlands washed away by the Lagam escarpment mudslides and Embosumer River on its lower section (April 2020).

Statement of the Problem
Although the Lagam escarpment landslides have taken place after ten years and are extremely deadly, no formal study has been conducted on them and consequently, very sparse literature exists on their occurrence, causes, and effects. This study was, thus, conducted to address these landslides and the geophysical factors surrounding them.

Objectives
This objective of the study is to investigate the causes of the recurrent landslides on the Lagam escarpment of Kaben location, Elgeyo-Marakwet County. The study will also propose possible mitigation measures to the landslide problem in the area of study.

Significance of the Study
It is hoped that the study will bring into the limelight the landslide menace affecting the people of the Kerio escarpmant, in its total stretch-covering Keiyo, Marakwet and Pokot regions. As an initial study on the Lagam landslides, it is desired that the study will draw the attention of the county and national governments, environmentalists, and scholars to the plight of the  The landslide prone area is watered by two rivers and their tributaries. The rivers are Embosumer and Emboreberwo. These two rivers originate from the lower edge of the Embobut forest, on the upland plateau, above the escarpment, to the west. Emboreberwo originates from the forest, while Embosumer oozes out of the escarpment, from a cliff face. It is believed that Embosumer is the product of an aquifer that disconnected when the Lagam escarpment and the Kerio Valley were formed through faulting. The river is also called Barelach (White water), owing to its brightness when it reflects the midday sun. Unfortunately, like all the escarpment rivers, Embosumer is on its deathbed, because of deforestation in Embobut forest, right above it, as the pictures show. The landslide area is almost two thirds of the whole Kaben location, and that makes this study crucial.

Data was collected through secondary data analysis.
Past studies and reports on the area of study and on the landslides were perused for relevant data. Satellite images of the area of study were also analysed besides online data sources. Ground photography supplemented data collection. Information has been presented in the form of analysed satellite images, pictures, and discussion of the study results.

Causes of the Periodical Landslides
The following factors are the collective causes of the recurrent Lagam landslides in Kaben location, Elgeyo-Marakwet County: the steep terrain of the escarpment, the nature of the escarpment soils, faulting of the escarpment rock masses, destructive human activities and heavy rainfall during the wet season

The Steep Terrain of the Escarpment
From the presented satellite images and pictures, it is succinct that the Lagam escarpment is acutely steep. This encourages water runoff/ surface flow after heavy downpours. The steep terrain also enhances the force of gravity on the escarpment overload material, making it vulnerable to sliding, especially when the soil mass is wet. The relief of the Lagam escarpment also comprises bare rock areas, rock outcrops, step faults, valleysincluding river valleys, interlocking spurs, hills, landslide lumps, fault scarps, slopes, and landslide scars. The hills are mainly products of faulting, weathering, and erosion. They may have formed when the Kerio Valley was formed and with time, denudation forces shaped them, coupled with vertical river/stream erosion. They form divides of the major escarpment rivers, though themselves possessing dry river valleys, which are basically the pathways of water runoff. Agricultural activities, on these hills, have heightened soil erosion,

The Nature of the Escarpment Soil
The Lagam escarpment is a young faulted rock mass which was formed at the same time that the Kerio Valley was fashioned, by nature, in the early Miocene period . This is also about the time that the Kerio River Fault line was formed. Consequently, the escarpment is covered by thin screen soils that are highly eroded. The soil is chiefly stony and unconsolidated, except in the escarpment's dales where alluvium is predominant. The thin screen soil has poor water retention capability, meaning that most infiltrated rainwater runs downhill as surface flow (deluge). On the upper parts of the escarpment, however, one encounters the upland plateau, to the west, and an expansive area of loose loam soils. This is where Embobut forest grows. As stated earlier, the escarpment soils seem to sit on a continuous sub-surface rock, which is poorly weathered and relatively smooth and compact, as seen from the landslide scars. This rock could be facilitating the sliding away of materials from the escarpment, especially in areas devoid of vegetation. The fault lines of Lagam escarpment are mostly invisible, having been filled by sediments and vegetation. They can, therefore, be identified through vegetation mapping; by looking for healthy vegetation lines in areas that do not have known surface water ways or through analysing satellite images of the areasuch as 8 and 9. The disjointed nature of the escarpment makes it easy for the escarpment's bare rock to become well lubricated by rainwater, so that it gets too slippery to hold the overlying weathered materials, hence landslides.

Destructive Human Activities
A band of environmentally harmful human activities are also responsible for the copious landslides on the Lagam escarpment of Kaben location and the wider Kerio escarpmant. These activities include: deforestation on the Lagam escarpment and the Embobut forest, detrimental agricultural practices and poorly done road shoulders

Deforestation of Embobut forest and destruction of the Lagam escarpment woodlands
The Lagam Escarpment has no actual forests. What it has can be described as an arid and semi-arid woodland comprising of thorn trees, among other drought resistant plants such as euphorbia. In the recent years, mango plantations have, admirably, taken over the Lagam escarpment, amid a horde of other tree crops such as avocado, lemon, banana, and pawpaw. Natural vegetation, thus, is giving way to manmade forests though in small pockets across the escarpment. The larger Kerio escarpmant is covered by some form of derived woodland, that is not fully recovered from slash and burn agriculture. Demand for agricultural land and charcoal burning have escalated deforestation, in the Lagam escarpment and the Embobut forest, to disastrous levels. This has resulted in a receding Embobut forest and an elongation of the escarpment that is stretching way into the upland plateau, a region that was darkly covered by a lush Embobut forest, 60 years ago. The elevated deforestation on the Lagam escarpment and the Embobut forest can be deduced from Plates 14 and 15, which are false colour Landsat images taken years apart (1986 and 2000). They show the Kerio River regime in the two periods. KIPKIROR JEPKEMBOI LOICE, KIPSANG BERNARD ROP AND WYCLIFFE HABEL NAMWIBA Plate 9: Kerio River regime in 2000 (Kipkiror, 2008). In the 1986 satellite image (Plate 8), the Embobut forest and the Lagam escarpment have rich plant canopies (deep red) and most of the escarpment rivers were shrouded in vegetation. The rivers reaching Kerio River, from the escarpment, were also more. The image shows about 8 countable rivers that had vegetation on their courses, as they wound their way into the Kerio River. Also, from the image, the large rivers appear to have had many tributaries that, themselves, had vegetation on them. The study area's rivers display a dendritic drainage pattern, separated by raised and semi bare divides and interfluves. The rocky areas (grey areas) of the escarpment, in the 1986 image, also appear to be less widespread compared to the rocky areas shown by the 2000 image. In the 2000 image (Plate 9), the vegetation cover appears to have thinned immensely, both on the Lagam escarpment and in the Embobut forest-as shown by the lightness of the red colour in the two areas. The rivers reaching Kerio River, from the escarpment, also appear to have reduced to 5, with some becoming seasonal. The rivers to the south of the area, covered by the image, have sand and rock trains on their beds-appearing whitish on the image. The rivers joining Kerio River, from the East, appear to have had some headwaters in 1986 (evidenced by vegetation) but by 2000, the rivers seem to have vanished-inheriting dry valleys (whitish). The photograph below (Plate 10), which was taken from near Wewo primary school, on the upland plateau, shows a section of the Embobut forest that has been mowed down, to pave way for agricultural land.

Plate 10: A section of the Embobut forest, adjacent to the Lagam escarpment (April 2020).
The clouds hanging on the area shown by the Plate 11, evidence the cool climate of the upland plateau. The bamboo twigs that make up the screen fence (Plate 16) do not only provide proof of deforestation of the Embobut forest but testify of the nearness of a bamboo forest. The picture also shows an elongation of the Lagam escarpment into the lower reaches of the upland plateau, besides showing landslide scars, poor farming practices (slash and burn agriculture) and a washed out Chesegon area.

Poor Agricultural Practices
Slash and burn farming regime, cultivation across contours, harrowing on steep riverbanks and fallowing are also responsible for the recurrent landslides on the Lagam escarpment in Kaben Location. During the dry season, the farmers of the Lagam escarpment often clear and burn bushlands to prepare land for cultivation. This does not only expose the land to agents of erosion and mass movement but also burn humus and other lithification elements that bind soil particles together. As a result, escarpment soils become loose and are easily carried away by wind and water. Lands on the rugged slopes of the escarpment are also hand-ploughed, vertically, along slope planes. This creates rills that quickly become gullies, where terracing is not done. Unfortunately, terracing does not provide a reprieve for landslides because, while stopping running soil, they also hold running water, percolating a lot of it into the soil. This intensifies soil wetness on the escarpment and encourages landslides. In the quest for extra farmland, riverbanks, on the Lagam escarpment, are cultivated. This encourages undercutting of the banks by water hydraulic force and easy collapse during flood seasons. The steepness of the riverbanks adds to the quandary of collapsing land, along the rivers, during the rainy season.

Poorly done road shoulders
Landslides on the Lagam escarpment are also experienced in areas where roads cut deep into the slopes. Road network, in the area, is still on high demand but the hanging road shoulders should be effectively steadied and stability measures applied on them, so as to guard against landslides. The escarpment road shoulders slide onto the road or down the escarpment, from the road surfaces at several localities. Plate 12 shows a road section on the Lagam escarpment. The road shoulders are not only steep, but loose. Deforestation and dangerous farming, on the escarpment, is also evident on the upper parts of the area shown by the photograph. The photograph also shows road instigated landslides. In 2019, a family of four were killed by a landslide that originated from a road above their house, when heavy rains hit Tuturung area of Marakwet East.
Plate 12: A section of a road on the Lagam escarpment.

Heavy Rainfall during the Wet Season
Climate change, which is a cross border global problem, is one of the factors behind the Lagam escarpment landslides. Global warming, which characterizes the current Climate Change phenomena, is choreographed by ruinous weather demonstrations that include: Haphazard rain patterns, Deviant rainfall intensity, Calamitous winds, High humidity, Supercharged clouds, Killer temperatures and Overcasting prolonged fog. These unforgiving weather exhibitions are trailed by melting of ice and snow, heavy river discharge, enlarged gobs of hailstones that take days to melt, lightning and thunder, poor visibility, disproportionate rain, discomforting gales, sweltering heat waves, freezing temperatures and poor visibility. In turn, these weather hazards lead to disasters of diverse kinds and magnitudes. It must be borne in mind that a hazard is a situation that is not currently causing harm but when it encounters some vulnerability, it transforms directly into a disaster (Disaster = Hazard + Vulnerability). On the Lagam escarpment/Kerio escarpment, thus, Global Warming has created irregular rain patterns and superabundant downpours, especially in the month of April. According to Mason and Gibson (1957) cited by Nyaberi et al. (2019), the Lagam escarpment and the Kerio valley received less amounts of rain, ranging from 750mm to about 1000mm per year. Rainfall was trimodal with first rains occurring in March, second rains in July/August and third rains in October/November, though the rainfall varies from place to place and is generally unreliable. Evaporation is also high in the area of study being about 2400mm per year (Kipkiror, 2008). This pattern of rainfall appears to have changed albeit slightly, so that the first rains occur in April and they are unusually heavy, being partially responsible for the recurrent landslides. In all probability, the Lagam escarpment April rains could be hitting a monthly average of over 100mm. In the other months, the area experiences a semi-arid type of climate that is characterised by high temperatures, sparse clouds (about 2 oktas), and gusty winds. This is broken by the light September -December rains.

RESULTS AND DISCUSSION
The following are the possible solutions to the recurrent landslides on the Lagam escarpment of Kaben location, Marakwet East and on the Kerio escarpment: Afforestation, effective land use, adaptation of sustainable agricultural practices and creating environmental awareness.

Afforestation
This is an exercise that should cover the Embobut forest and the Lagam escarpment; and it can be done in piecemeal. It is no secret that a large section of the Embobut forest has been cleared, especially the areas adjacent to the Lagam escarpment. Clearing of the forest cover has contributed to runoff of considerable volumes of water that goes down the escarpment, as non-percolated rainwater increases in the steep forest margins. This great deluge shoots up the landslide problem. Afforestation can be done using crop trees, for both the forest and the escarpment. Avocado, plum, pear and other cold temperature fruit trees can be planted on the edges of the forest, where people own land-instead of planting maize, beans, and potatoes. On the Lagam escarpment, the people can plant mango, banana, pawpaw, and lemon, instead of maize, millet, and other grass crops. These crops will not only hold the escarpment soil together but will earn the residents some much needed cash. Maize and seasonal crops can be planted in created plantations in the Kerio Valley. The valley is flat, fertile and very suitable for mechanized farming. The communally owned tracts of valley land can be jointly farmed, weeded, and harvested, then whatever is harvested is shared among the clan families. Such kind of farming will not only make the valley useful but will stop cattle rustling that makes Kerio Valley inhabitable-more so if the joint valley farming practice is replicated across Kerio River, on the Pokot side of the valley. The entire Lagam escarpment should be greened, from North to South, vice versa.

Effective land use
Currently, there is heavy settlement on the steep slopes and valleys of the Lagam escarpment, which goes hand in hand with extensive farming. Since resettlement has been an arduous task for the government and there is a lot of cultural value attached to land in the study area, the escarpment land can be used in a way that landslides are inhibited. First, homestead grounds on the Lagam escarpment, should be made stable and environmentally safe. Trees and grass should be grown around compounds so that no land is left bare for runoff to act on. Secondly, farming on riverbanks and the very steep areas of the escarpment should be ceased. If farming must be done, then it should be the growing of tree crops, in areas that are well terraced. The tree crops can be intercropped with cereals or legumes to ensure a continuous vegetation cover. Thirdly, the construction of roads and other infrastructure, on the Lagam escarpment, should be done after much environmental consideration is done. A comprehensive ESIA (Environmental/Social Impact Assessment) should be carried out for all construction projects so that the land is left more stable in the after-project period than in the pre-project time. This way, road constructioninitiated landslides will be curbed. Fourthly, charcoal burning and other forms of deforestation, in the study area, should be stopped. Grass laced terraces should also be constructed across the Lagam escarpment, to stabilize the soil and guard against excessive water runoff, mostly in areas devoid of vegetation and in farmland areas. This was the practice in the past when population explosion was not as high as now and people did not settle haphazardly on the escarpment. The faulted areas of the Lagam escarpment, together with the areas that have loose rock boulders, should be covered with trees. The trees' root network will hold the soil and rocks together, propagating soil formation as roots and humic acid weather the independent and faulted rocks. For own safety, people should avoid settlement on flood paths and river valleys, where they are exposed to flash floods and landslides.

Adaptation of sustainable agricultural practices
The people of the Lagam escarpment (and the Kerio escarpment) must do away with slash and burn agriculture, cultivation across contours, keeping of large herds of grazers on the escarpment and land fallowing. Slash and burn agriculture loosens soil, making it vulnerable to erosion and landslides. Cultivation up the slope creates grooves that enhance rill erosion while grazing many animals on the escarpment will cause bareness of land and encourage rock falls. The scars left behind by falling rocks will form the bases for future landslides. Fallowing, on the other hand, causes land redundancy and might expose land to natural agents of land degradation, as land is abandoned for a while. Lack of constant land care means that land might be eroded or mishandled by nature, at will.

Creating environmental awareness
The recurrent nature of the Lagam landslides and the devastation that accrues shows some knowledge/ information gap among the area residents. This calls for environmental education that may be done by the National/County government, experts from relevant national departments or a trained team of locals. This team will act as environmental watch dogs; training people on environmental conservation, scouting for signs of environmental disasters and disseminating information on disaster preparedness and environmental safety. Patwardhan (1999) highlighted two pertinent issues that need to be addressed in order to avoid re-occurrence of landslides, as geo-environmental hazards. The two issues are: 

CONCLUSION
Mapping of a study area so as to identify slopes which are susceptible to landslides,  More input for applying adequate conservation efforts to vulnerable steep slopes is sought for from stakeholders. Since 1999, interpretation of satellite images has been undertaken for better understanding of the geotechnical features of the study area such as, faults, tectonic joint systems etc. Furthermore, slopes that are vulnerable to landslides have also been identified and it can now be concluded, for the present, that;  The main factors triggering landslides are over saturation of soil and rock materials due to heavy downpour, depletion of vegetation on the steep rugged Lagam escarpment and escarpment slopes caused by human activities.  The slopes of the Lagam escarpment/ridges, that are prone to landslides, are very unstable and not fit for human settlement.  The most affected areas are Kipchumwa and Kaben Locations, though the effects of the landslides worsen downstream at Kitony, Cheptokou, Sambalat, Liter and Chesegon areas.  Consequently, there is need for an in-depth research, in the study area, beyond the present initial study, especially along the entire Lagam escarpment and associated ridges.