Climate change and variability are projected to alter the geographic suitability of lands for crop cultivation. In many developing countries, such as Kenya, information on the mean changes in climate is limited. Therefore, in this study, we model the current and future changes in areas suitable for rainfed maize production in the country using a maximum entropy (MaxENT) model. Maize is by far a major staple food crop in Kenya. We used maize occurrence location data and bioclimatic variables for two climatic scenarios-Representative Concentration Pathways (RCP) 4.5 and 8.5 from two general circulation models (HadGEM2-ES and CCSM4) for 2070. The study identified the annual mean temperature, annual precipitation and the mean temperature of the wettest quarter as the major variables that affect the distribution of maize. Simulation results indicate an average increase of unsuitable areas of between 1.9–3.9% and a decrease of moderately suitable areas of 14.6–17.5%. The change in the suitable areas is an increase of between 17–20% and in highly suitable areas of 9.6% under the climatic scenarios. The findings of this study are of utmost importance to the country as they present an opportunity for policy makers to develop appropriate adaptation and mitigation strategies required to sustain maize production under future climates

Ecohydrological changes in large rivers of the world result from a long history of human dimensions and climate. The increasing human population, intensified land use, and climate change have led to a decline in the most critical aspect of achieving sustainable development, namely, that of water resources. This study assessed recent hydromorphological characteristics of the tropical Tana River in Kenya using flow duration curve, and geospatial techniques to gain a better understanding of human impacts over the last two decades and their consequences for new development projects. The results show that all extremal peak, low, and mean discharges exhibited significant increasing trends over a period of 17 years. Dam construction represents a 13% reduction of the maximum discharge and a 30% decrease in low flows, while post-regulation hydrological changes indicated an increase of 56 and 40% of high flows and low flows respectively. Dominant flow was observed to be higher for the current decade than the previous decade, representing a rise of the dominant streamflow by 33%. The assessment of four morphologically active sites at the downstream reach showed channel adjustments which support the changes in the flow regimes observed. The channel width increased by 8.7 and 1.9% at two sites but decreased by 31.5 and 16.2% for the other two sites under study during the time period. The results underscore the contribution of other main human modifications, apart from regulation, such as increased water abstraction and inter basin transfer, up-stream land use and anthropogenic climate change to assess the ecohydrological status in this river basin. Such streamflow regime dynamics may have implications on water resource management, riverine environments, and development of new water projects.

Deforestation poses a threat to sustainability of forest ecosystem services and socio-economic development in many parts of Kenya. Understanding the trend and extent of forest cover changes and the underlying driving forces over time is pertinent for sustainable management of ecosystems. However, in many parts of the country, such information is still somewhat unknown due to limited data availability for multi-temporal analysis. This paper focuses on western Kenya, a major agricultural region of biodiversity and water catchments that are under threat from forest cover dynamics. The study analyses the status of the forests in the region with the aim of determining the areal extent of coverage, trends in forest cover, drivers of change and associated impacts of deforestation. To achieve these objectives, remote sensing techniques were used to undertake supervised classification on Landsat images of 1995, 2001, 2010 and 2017 with classification scheme of forest and non-forest land cover classes. The results of the study showed that the changes in forest cover varied over time and space. There was considerable net gain in forest areas by about 43% between the period 1995–2001, and thereafter, a continuous decrease ending in a 12.5% loss by 2017. Deforestation in the region is caused by a combination of complex factors that include population pressure, politics and failures in implementation of policy. This study determined the forest cover dynamics and driving forces across diversified sub-basins, an approach that had not been used by previous studies in the region. Thus, the findings will provide valuable information for decision making pertaining to integrated land use and catchment management in order to realize the enormous benefits of sustainable forest ecosystems. The information will not only be important to the study area, but equally applicable to similar tropical regions.

This study examined the impact of land use/cover changes on soil erosion in western Kenya in the years 1995 and 2017. The study used the GIS-based Revised Universal Soil Loss Equation (RUSLE) modelling approach and remote sensing assessment. The results showed that the average soil loss through sheet, rill and inter-rill soil erosion processes was 0.3 t/ha/y and 0.5 t/ha/y, in the years 1995 and 2017, respectively. Of the total soil loss, farms contributed more than 50%, both in 1995 and 2017 followed by grass/shrub (7.9% in 1995 and 11.9% in 2017), forest (16% in 1995 and 11.4% in 2017), and the least in built-up areas. The highest soil erosion rates were observed in farms cleared from forests (0.84 tons/ha) followed by those converted from grass/shrub areas (0.52 tons/ha). The rate of soil erosion was observed to increase with slope due to high velocity and erosivity of the runoff. Areas with high erodibility in the region are found primarily in slopes of more than 30 degrees, especially in Mt. Elgon, Chereng’anyi hills and Elgeyo escarpments. This study forms the first multi-temporal assessment to explore the extent of soil erosion and seeks to provide a useful knowledge base to support decision-makers in developing strategies to mitigate soil erosion for sustainable crop production.

Climate change and variability are a major threat to the agricultural sector globally. It is widely accepted that the changes in temperature, rainfall patterns, sea water level and concentration of CO₂ in the atmosphere will have the most devastating impacts on agricultural production. This paper examines the past and future crop production and food security in Kenya under variable climate. From the review, it is evident that the country is already experiencing episodes of climate change, manifested by seasonal changes in precipitation and temperature of varying severity and duration despite overreliance on rain-fed agriculture. The findings also reveal that climate change would continue to negatively affect crop production and food security to the already vulnerable communities in the arid and semi-arid areas. Future projections also indicate that climate variability will likely alter cropping patterns and yields in several regions. As the country is faced with a high population growth rate and rapid urbanization, crop production and food security systems need to become more adaptive as uncertainties of projected climate variability and change unfold. This study is important in providing decision makers and interested stakeholders with a detailed assessment of climate impacts and adaptation strategies geared towards improved crop production and food security.

The western region of Kenya is experiencing remarkable land changes resulting from population growth and related impacts. The study used remote sensing and GIS techniques to analyze the land use/cover changes in the years 1995, 2001, 2010 and 2017. Multi-spectral Landsat (TM, ETM + and OLI) images were pre-processed and classified using maximum likelihood algorithm in ENVI version 5.4. The overall classification accuracies in all the images were more than 80%. The results revealed major conversions of each land use/land cover type in varying trends and magnitudes. Between 1995 and 2001, there was an increase in built-up areas by 71%, forest cover by 43%, farms by 5%; and decrease in grassland by 47%. By 2017, the built-up areas had increased by 225% and farms by 17%; the forestland, grassland and water reduced by 38, 10 and 11%, respectively. The observed changes are characterized by increased settlements and encroachment of sensitive ecosystems.

Understanding the long‐term variability and change in climate variables is critical for the sustainable management of water resources. This research aimed to project and analyse climate change in the Awash River Basin (ARB) using bias‐corrected Global and Regional Climate Model simulations. The analysis included a baseline period from 1986 to 2005 and two future scenarios (2050s and 2070s) under two representative concentration pathways (RCP4.5 and RCP8.5). Following the evaluation of bias correction methods, the distribution mapping and power transformation were used for temperature and precipitation projection, respectively. The 2050s and 2070s RCP4 simulations showed an increase in precipitation during half of the months with 32 and 10%, respectively. Moreover, the 2050s and 2070s RCP8.5 simulation indicated a decrease in precipitation with 18 and 26%, respectively. The 2050s and 2070s RCP8.5 simulation indicated a significant decrease in precipitation in four of the months (February/March to May) with the highest decreasing rate of 34.7%. The 2050s and 2070s RCP4.5 simulation showed an increase of 0.48–2.6°C in maximum temperature. In the case of RCP8.5, the simulated maximum temperature increase reached 3.4 and 4.1°C in the 2050s and 2070s, respectively. The future precipitation and temperature change projected in ARB might worsen the water stress and incidence of dry spells in the basin, and hence mitigation strategies and management options to reduce this negative impact should be developed.

Watershed morphometric assessment is about measurements and calculations of land surface forms for the purpose of understanding hydro-geomorphological character and patterns. Important natural environment geo-information and summary of the spatial characteristics of Tana River Basin (TRB) in Kenya have been obtained through hydro-geomorphometric analysis. Advanced Spaceborne Thermal Emission and Reflection Radiometer Digital Elevation Model (ASTERDEM) data and ArcGIS (ESRI Inc., version 10.4.1) together with published mathematical equations were applied to extract morphometric parameters of the drainage basin, which covers a total area of 94,930 km² and a span of 527.75 km. The quantitative morphometric analysis considered a total of 28 relief, areal, and linear hydro-morphometric characteristics of the TRB. Relief parameters of the basin suggest moderate-to-low overall watershed steepness, upland with rolling land surface patterns, rugged landforms susceptible to erosion and sediment transportation, and a landscape in evolution process tending towards maturity. This means stability of the land surface can be attained with intensive land degradation reversing strategies like erosion control measures. Areal characteristics further support the basin's susceptibility to erosion as shown by stream length, stream drainage density, and circulatory ratio values. Also, the areal aspects portray peak runoffs with short duration flashes. Linear parameter value results such as bifurcation ratio imply that infiltration capacity varies with stream orders across the watershed. This hydro-geomorphometric analysis would be useful to land and water managers, researchers and practitioners of TRB, and other similar systems in designing and planning soil and water conservation and management practices such as soil erosion control, groundwater recharge activities, catchment modelling, runoff and flood studies, prospecting groundwater mapping, and biological applications.

River channel dynamics are natural autogenic occurrences for fluvial rivers with influences from human modifications and climatic factors. Remote sensing and geographic information system tools and techniques, aerial photographs, and satellite imagery have been used to determine epochal channel erosion, accretion, and unchanged locations along Tana River, Kenya's longest river. Six reaches within a 142-km Saka-Mnazini stretch were studied by comparing sequential changes in the position of the channel in 1975–1986, 1986–2000, 2000–2017, and 1975–2017 epochs. Manual and automatic digital processing procedures and GIS tools were applied to visualize and quantify the reach-wise spatial and temporal morphological changes. The erosion and accretion channel changes over the study period were observed and quantified at all reaches. Meandering and switching off or abandoning the main active channel was also illustrated. The potential driving forces of morphological changes included varying hydrological regime, upstream land use practices, nature of channel gradient, and riparian vegetation occurrence changes. We found no clear evidence to link river regulation with the river channel dynamics. Results deliver the latest evidence on the dynamics of Tana River. This information is crucial for understanding river evolution characteristics and aid in planning and management at the lower reaches which has remained poorly understood. Use of remote sensing data in concert with GIS provides efficient and economical quantitative spatial and temporal analysis of river channel changes.