Intergrated Water Resources Management

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Effect of thermal treatment on the pozzolanic activity of natural clay from selected Kenyan wetlands
(Journal of Sustainable Research in Engineering, 2023) Kyungu W. N. Yannick, James W. Kaluli, Benson M. Mwangi, and Hosea M. Mwangi
The use of cement in construction is costly and degrades the environment. Therefore, affordable and easily available alternatives are needed. This study evaluated the effect of thermal treatment on the pozzolanic activity of clay soils. Three wetland clays collected from three sub-counties of Murang’a County, Kenya (Kahuro, Kiharu and Maragua Sub-Counties) were studied after thermal activation. Thermal treatment (calcination) was carried out in an electronic muffle furnace (Advantec KL-420) at 600, 700, and 800°C for a duration of 2 hours. The chemical oxide composition was evaluated using X-ray fluorescence (XRF). Three methods (electrical conductivity, Frattini test, and compressive strength test method) were used to assess the pozzolanic activity of clay. A decrease in the electrical conductivity of the lime-clay solution was observed over a 24 hour period. Results of the Frattini test showed that clay calcined at 600°C and 700°C reacted with Ordinary Portland Cement (OPC) - CEM-I and reduced CaO and OH- concentrations to levels below the solubility curve of Ca(OH)2. Calcination of clay from Kahuro and Maragua sub counties, at 600°C and 800°C, respectively, increased the strength activity index of cement blocks from less than 0.75 to about 1 after 28 days of curing. Therefore, a temperature range of 600-800°C was considered effective for calcination. We conclude that thermal treatment increases the pozzolanic activity of natural clay for use as a replacement for cement. Therefore use of blended cement may be a sustainable alternative to the use of cement alone.
Seasonal Habitat Shifts and Wetland Dependence of Grey Crowned Crane in Urbanising Kenya
(John Wiley & Sons Ltd., 2025-06-26) Carolyne M. Wachu, Benson M. Mwangi, James Jumbe, Wanyoike Wamiti, Joseph Mwangi
The Grey Crowned Crane (Balearica regulorum) has experienced major global population declines, leading to its uplisting to Endangered status on the IUCN Red List of Threatened Species. In Kenya, the Nairobi metropolitan area supports one of the country's substantial remaining populations of this species, yet data on temporal and spatial variation in population and habitat associations remain limited. This study conducted systematic censuses at 130 sites across five counties between June 2023 and February 2024 to assess patterns in population and habitat use across wet and dry seasons. The observed crane population was estimated at 1116 individuals, based on the average of wet and dry season counts, with seasonal crude den sities of 0.127 individuals/km2 in the wet season and 0.14 in the dry season. Adults comprised 93.6% and young individuals 6.4%, with Kiambu County recording the highest proportion of young cranes (44.4%). Crane abundance varied substantially among counties and was positively associated with the availability of suitable wetland habitats. Habitat use shifted seasonally, with greater wetland occupancy during the wet season and increased use of grasslands during the dry season. These patterns highlight the species' strong dependence on wetlands and its flexible foraging behaviour in modified landscapes. Our findings emphasise the ecological value of even small or degraded wetlands and call for their integration into urban conservation and land use planning frameworks.
Modeling the Niche Suitability of Grey Crowned Crane (Balearica regulorum) to Inform Conservation Strategies in Kenya
(British Ecological Society and John Wiley & Sons Ltd., 2026-03-26) Carolyne M. Wachu, Benson M. Mwangi, James Jumbe, Wanyoike Wamiti, Denis Kiptoo
The Grey Crowned Crane is listed globally as Endangered, primarily due to threats such as habitat loss, degradation, and frag mentation, as well as human encroachment, electrocution, and illegal capture. Effective conservation requires knowledge of the species' current and future spatial distribution under changing climatic conditions. This study addresses these knowledge gaps by assessing the climate suitability and spatial distribution of the species in Kenya under current and future climate sce narios. Using occurrence data from the Global Biodiversity Information Facility and climatic variables from WorldClim, species distribution models were developed to evaluate the species' suitable habitats. The influence of climatic predictors on species distribution was assessed under two climate change scenarios (SSP2- 4.5 and SSP5- 8.5) for the period 2020–2040. An ensemble modeling approach combining Generalized Linear Models, Generalized Additive Models, and Random Forest algorithms was used to predict suitable crane habitats. The distribution map was overlaid with protected area boundaries to assess the coverage of habitat protection. Results indicate that suitable habitats are largely concentrated in western and southwestern Kenya, with distribution strongly influenced by temperature and precipitation. The predicted reduction in suitable area, about 49.5% under SSP2- 4.5 and 47.5% under SSP5- 8.5, highlights the vulnerability of the species to changing climatic conditions. Projections under the two climate change scenarios revealed a potential contraction in the suitable range, indicating possible adverse impacts of climate change. These findings provide insights into the climatic drivers of Grey Crowned Crane distribution and offer a basis for informing conservation planning and habitat management under future climate change
Wetland Degradation Status and Conservation Challenges in Murang’a County, Kenya
(International Journal of Ecosystem, 2021) Benson M. Mwangi
Unregulated human activities have resulted in massive degradation and eventual loss of wetlands despite their importance in providing various ecosystem services and habitat to important species of fauna and flora. In Murang’a County, Kenya, wetland degradation has increased at an alarming rate since the 1980s, with no data on their degradation status and challenges facing their conservation. This study aimed to examine the trend of wetland degradation and the main challenges impacting their conservation in Murang’a County between 1986 and 2018. The challenges were identified in a stakeholder workshop involving 39 key stakeholders and ranked in order of importance using the pair-wise ranking technique. Trends in wetland degradation status were assessed through analysis of land use maps obtained from Landsat images of 1986, 2001, and 2018. The most critical challenges affecting the conservation and management of wetlands in the County were inadequate legislation followed by poor planning, lack of community empowerment, scarce resources, corruption, encroachment, and pollution. Correlation analysis between wetland and water areas showed a significant but negative relationship at (P<0.01), indicating that decreasing wetland areas resulted in a significant reduction of water areas. The wetland area in the County decreased by about 48% between 2001 and 2018 and to arrest this trend of declining wetland area, the stakeholders recommended the amalgamation of all laws and policies touching on conservation and management of wetlands in the County. Further, there is a need for community involvement and empowerment to create awareness of the roles of wetlands for their well-being.
Threats of Land Use Changes on Wetland and Water Areas of Murang’a County, Kenya
(Published by Science and Education Publishing DOI:10.12691/aees-9-6-2, 2021) Benson M. Mwangi
Globally, wetlands have declined in area by over 50% since 1900, due to changes in land-use patterns, converting them into farmlands, human settlements, urban centers, and infrastructure development. Land-use changes also impact negatively on the water area (streams, rivers, lakes, reservoirs, and sea) of an area. In this study, the threats of land use changes on wetland and water areas in Murang’a County, Kenya, were assessed, in a bid to understand the main causes for the rapid decline in wetland and water areas in the County. Landsat images of 2001 and 2018 were analyzed using a supervised classification technique to produce Land-use maps in ArcGIS and detect associated changes. Between 2001 and 2018, the wetland area in Murang’a County declined by over 48% while the water area declined by over 25%. Bare-soil/built-up area posed the greatest threat to the conservation of wetlands in the County, taking up 161 ha of the wetland area during the period. The growth of woody shrubs posed the greatest threat to the loss of water areas taking up 152 ha of the water area during the period. Mean total threats facing wetlands differed significantly from mean total threats facing water areas in the County (t = 0.682; p<0.001). It is concluded that wetland and water areas are faced with similar human-induced land use threats but at varying magnitudes. It is therefore critical that specific regulatory legal and policy structures be urgently instituted to curtail further wetland and water area losses.
Evaluation of Wetland Loss in Maragua Watershed, Murang’a County, Kenya
(Journal of Sustainable Research in Engineering, 2018) Jacinta M. Muema, J.W. Kaluli, J.M. Gathenya and B.M. Mwangi
Wetlands are habitat to a wide range of biodiversity and thus accommodate some of the world’s most valuable resources. Unfortunately, their ecosystem services are continuously being lost to destructive anthropogenic activities. Systematic wetland mapping and inventorying to establish wetland status is necessary. A study was therefore done to determine the wellness of wetlands; and the temporal and spatial changes in wetlands in Maragua watershed. Normalized Difference Water Index (NDWI), Normalized Difference Vegetation Index (NDVI) and Topographic Wetness Index (TWI) were used to extract wetlands areas. Additionally, interviews, storytelling events, stakeholder workshop, focus group discussions and personal observations were used to obtain qualitative data on human activities in wetlands and the challenges facing wetlands in the study site. In 1987 the area under wetlands in Maragua was 24.1 ha, in 1999 it was 12.8 ha and by 2018 wetlands covered only 10.1 ha. Further, the wetlands are more concentrated on the downstream side of catchment. Additionally, wetland cultivation, planting of exotic trees and fodder grass farming are the main human activities taking place within the wetlands. It was observed that the local communities are neither aware of the adverse effects of their activities on the wetlands nor the potential benefits of conserved wetlands. With the help of various stakeholders, the County Government of Murang’a has opportunities to create awareness and educate the residents of the study area about the potential benefits of conserving their wetlands.
Effects of Land Use and Land Cover Change on Potential Ecosystem Service Value in Mathioya Watershed, Murang’a County, Kenya
(Journal of Sustainable Research in Engineering, 2022) Movin O. Oginga, James W. Kaluli, Benson M. Mwangi and James M. Raude
Wetlands in Mathioya watershed are declining due to continued alterations caused by human and natural factors. This study assessed the effects of spatiotemporal changes in Land Use and Land Cover (LULC), on potential ecosystem service value in Mathioya watershed, Murang’a County, Kenya. We considered the period between 1987 and 2020. Supervised classification using maximum likelihood classifier was performed in ERDAS imagine v.15. The values obtained from the analysis of LULC maps were then used together with the global data for habitats to approximate the ecosystem service value (ESV) change within the watershed. Six LULC classes namely, forestland, wetlands, agricultural land, water bodies, built-up areas and barren lands, were identified. Analysis of Landsat images revealed that between 1987 and 2020, human activity led to decrease in the area covered by wetlands, forestland, water bodies, and barren land. Area under these land cover classes decreased by 45%, 34%, 50% and 27%, respectively. During the study period, agricultural land and built-up areas increased by 43% and 85%, respectively. Changes in LULC resulted in decline of ESV from $368.5 million/ha/year in 1987 to $337.7 million/ha/year in 2020. With respect to individual ecosystem services, regulating services declined. Between 1987 and 2020, water regulation and climate regulation declined by 48% and 16%, respectively. However, provisioning services such as food production increased by 34%. Wetlands play a critical role in the provision of ecosystem services. The loss of wetlands translated to decline of critical ecosystem services such as water regulation. Eventually, this will lead to poor water quality within the watershed and the entire County, thus impacting negatively on the health of the locals. Hence, there is a need for urgent action to prevent the current trend of wetland loss within Mathioya watershed.
Effects of Catchment Land Use on Nutrients and Heavy Metals Inflows into Maragua and Mathioya Wetlands in Murang’a County, Kenya
(International Journal of Research and Innovation in Applied Science (IJRIAS), 2025-05-08) Evans Kipkemoi, Warren Andrew Andayi, B.M. Mwangi, Eric C. Njagi and Margaret W. Kariuki
etland ecosystems in Murang’a County are diminishing due to increased catchment land use practices. Part of wetlands have been converted into farmlands where various agricultural activities are carried out while some parts have been converted into settlement points. Agricultural practices carried out along wetland ecosystems involve the use of excessive agrochemicals during crop production which later contribute to wetland pollution through nutrients and heavy metals inflows. This study aimed at assessing the effects of catchment land use on nutrient and heavy metals inflows into Maragua and Mathioya river basins in Murang’a County. Water samples were collected using the Grab technique, packed in plastic containers, kept in cool boxes, and transported to the research laboratory for analysis. Phosphate and nitrate concentrations were analyzed across different seasons, sampling stations, and sampling levels. During dry season, the mean phosphate concentration was 0.0259 ± 0.0051 mg/L with a standard deviation of 0.0124 mg/L. In wet conditions, the mean phosphate concentration increased to 0.1631 ± 0.1509 mg/L with a standard deviation of 0.3697 mg/L. For nitrate, the mean concentration during dry conditions was 9223.37 ± 2672.33 mg/L with a standard deviation of 6545.84 mg/L, and during wet conditions, it remained the same at 9223.37 ± 2008.17 mg/L with a standard deviation of 4919.00 mg/L. Elemental analysis was performed using Microwave Plasma-Atomic Emission Spectroscopy (MP-AES) instrument. Mean concentrations of lead during dry seasons were 0.005 ± 0.002 mg/L and during wet season, they increased to 0.012 ± 0.004 mg/L. Zinc concentrations were 0.01 ± 0.003 mg/L during dry season and increased to 0.015 ± 0.004 mg/L during the wet season. The mean concentrations of zinc in the water samples were significantly lower than the maximum residue concentrations set for drinking water by the World Health Organization (WHO). However, lead (Pb) concentrations were above the WHO recommended maximum residue level. ANOVA analysis indicated no significant seasonal differences in phosphate (F=0.825, p=0.385) and nitrate (F=3.090, p=0.109) levels. Similarly, no significant differences were found between different sampling stations for phosphate (F=1.081, p=0.323) and nitrate (F=0.478, p=0.505). Analysis by sampling levels showed no significant differences noted for phosphate (F=0.979, p=0.412) and nitrate (F=1.949, p=0.198). For heavy metals, no significant differences were found for lead (F=1.234, p=0.271), cadmium (F=0.893, p=0.348), and zinc (F=1.567, p=0.223) across different seasons and sampling stations. These findings suggest that nutrient and heavy metal inflows into the wetlands are relatively stable and uniform across different spatial and temporal scales. The study highlights the importance of consistent land use practices and the effective buffering capacity of wetlands in maintaining ecological balance.
Removal of Nitrites from Wetland Waters Based on Diazonium Silica
(American Journal of Chemistry, 2025) Aquiline Kathambi, Peter W. Njoroge, Sylvia A. Opiyo, Isaac Waweru, Benson M. Mwangi
Diazonuim silica was prepared and used to remove nitrites in wetland waters. Raw silica was chlorinated using phosphorous pentachloride (PCl5). Chlorinated silica was further reacted with ethylenediamine (EDA) under reflux to give aminated silica. Thereafter, aminated silica was protonated to yield diazonium silica which was used as the adsorbent. The prepared diazonium silica material was characterized using Fourier Transform Infrared (FT-IR) showing bands at wavenumbers 1049 and 791 cm-1 of the anti-symmetric and symmetric stretching modes (Si-O-Si) of SiO4. The shift in spectra band of Si-O-Si from 1051cm-1 in raw silica to 1049cm-1, was attributed to diazonium silica. Additionally, a new open chain azo (N=N) group band was found in the region 1575cm-1 -1630cm-1. The physical adsorption parameters examined using batch adsorption system including: pH, initial concentration, contact time and temperature were made using sorption models, adsorption kinetics and thermodynamics. The results obtained showed 3.0 as the optimal pH for adsorption of NO2-, 303K as the optimal temperature, optimum contact time as 60 minutes and optimal initial concentration as 20ppm. The adsorption capacity of nitrites using diazonium silica adsorbent was achieved at 16.45mg/g. For sorption of nitrites in diazonuim silica, Langmuir isotherm model was obeyed according to correlation coefficient R2 = 0.97182 close to unity. Adsorption kinetics of nitrites in diazonium silica pseudo second order was best obeyed while, thermodynamic parameters revealed that the sorption of nitrites into diazonium silica was exothermic in nature. From the results obtained, diazonium silica is an efficient adsorbent for adsorption of nitrites compared to raw silica.
Adsorptive removal of phosphates from wetland waters using silica molyb date adsorbent
(Journal of Emerging Technologies and Innovative Research, 2025-02) Aquiline Kathambi, Peter W. Njoroge, Sylvia A. Opiyo, Isaac Waweru, Benson M. Mwangi
World’s most productive and valuable ecosystem is the wetlands. Quality and functions of wetlands have been affected adversely by deforestation, fertilizers, and pesticides among others. Pollution by phosphates affect aquatic life as they have serious side effects at very low levels. Silica molybdate was prepared by first chlorinating silica sand using phosphorous pentachloride (PCl5) to give chlorinated silica. Amination of chlorinated silica was done using Ethylenediamine (EDA) and later molybdate was chemically grafted to the aminated silica to yield silica molybdate. Silica molybdate was used to reduce the levels of PO4 3- residues from wetland ecosystem.. Molecular structure of the silica molybdate material was characterized using Fourier Transform Infrared (FT-IR). FT-IR results showed Adsorption bands at 854cm-1 and 542cm-1 which were attributed to Mo=O and Mo-O stretching in molybdate. Peaks observed at 1388 and 1662cm-1 were attributed with the vibration mode of Mo-OH bond and bending mode of adsorbed water. Spectra peaks observed at 542, 634.58 and 898.97 cm-1 were attributed to the adsorption of molybdate. The physical adsorption parameters which were examined using batch adsorption system were; temperature, pH, contact, time, initial concentration using sorption models, adsorption kinetics and thermodynamics. Results showed that optimum pH for biosorption of PO4 2- was 6.0, optimal contact time was 30 minutes, optimum temperature was 45 ℃. The experimental results obtained showed that the maximum phosphate adsorption of silica molybdate was achieved at 194.93mg/g at adsorption optimal conditions of pH, temperature and contact time. The phosphate removal based on silica molybdate will offer several benefits such as low cost, effectiveness and reliability to lower the levels of phosphates in wetland waters as compared to commercial activated carbon. Based on the adsorption efficiency values obtained from this study and comparing them with adsorption efficiency reported in the literature, it can be concluded that silica molybdate is super adsorbent for the removal of phosphates from wetland waters.
Sustainability of Livelihood Strategies of Riparian Communities in Murang’a County, Kenya.
(nternational Journal of Humanities and Social Science Invention (IJHSSI), 2021-06) Isaiah Ochieng Abillah, Dr. Benson Mwangi, Prof. Richard Juma, Prof. Clifford Machogu
Wetlands have played a key role in support of the riparian community’s livelihoods and development and have been the source of forest, wildlife, minerals, agriculture, recreation, water and energy. Murang’a County in Kenya, is endowed with many such wetlands that provide water to nearby towns of Thika and Nairobi city. Despite these important roles, wetlands conservation and management in the county continue to attract little attention from scientists and policy makers. This study aims at investigating the livelihood strategies of riparian communities in Murang’a County, Kenya. This study aimed at investigating how sustainable the livelihoods strategies are of the riparian communities are in Murang’a County. The study was conducted in four purposively selected sub-counties, due to their richness in wetlands: Kiharu, Kangema, Mathioya, and Maragua. Data was collected using household’s survey questionnaires, key informant interviews, and focus group discussion. Questionnaire were administered to a randomly selected sample of 404 respondents from the riparian community in the four sub-counties. Data was analyzed using SPSS software version 26.0. Chi-squared test was used to test for association between livelihood strategies and effects of encroachment into wetlands. Rejection value for statistical tests was set at P< 0.05. Results showed an encroachment rate into the wetlands by the riparian communities of 60.4%. It is concluded that livelihood strategies of riparian communities were not sustainable due to a high rate of encroachment, inadequate enforcement of laws and policies, On the other hand, over exploitation of wetlands resources, lack of knowledge on wise use of wetlands and conflict of interest among different environmental conservation institutions among other factors, were impacting negatively on wetlands conservation in Murang’a County. The study recommends enhanced sustainability of livelihood strategies of riparian communities through empowerment, capacity building and well-coordinated livelihood strategies by all stakeholders in wetlands management that will lead to the wise use of wetlands ecosystems in Kenya and in other parts of the world.
Gender Roles in Wetlands Conservation and Restoration in Murang’a County, Kenya
(International Journal of Humanities and Social Science Invention (IJHSSI), 2021-06) Isaiah Ochieng Abillah, Dr. Benson Mwangi, Prof. Richard Juma, Prof. Clifford Machogu
Women are the majority vulnerable in wetlands access and control, yet livelihood provisioning services bring her in direct contact with and control of wetlands on a daily basis. Murang’a County is majorly a patriarchal society and women continue to experience the worst forms of oppression and exploitation in environmental management. Therefore, the purpose of this paper is to determine the gender roles in community- based strategies aimed at Wetlands conservation and restoration in Murang’a County, Kenya. It adopted a descriptive survey design with a target population of 144,376 divided into four Sub-Counties of Murang’a. Simple random sampling was used for each stratum to select a sample of 404 respondents. Key Informant interviews, focus group discussion, and documentary analysis were used to corroborate responses from the questionnaires. Qualitative data were coded before the analysis. Quantitative and qualitative data were analyzed using SPSS software version 26.0. Continuous variables were analyzed using a Chi-Square test and P values of <0.05 at 95% confidence interval level was considered significant. The study revealed that there is gender inequality in conservation efforts due to poor policies, beliefs, lack of knowledge, and skills. The study thus recommends effective gender role equity in wetlands conservation efforts.
Water Resource Management Approaches for Sustainable Development in Kipkelion West SubCounty, Kenya
(IJRASET, 2020-07) Sitienei Anne
Although water is an important resource, it is threatened by anthropogenic activities both nationally and globally. Therefore, the present study sought to establish management strategies used in water resource management in Kipkelion West Sub-County within Kericho County, Kenya. The study population comprised of households and water management agencies within Kipkelion West Sub-County. A total of 394 households were randomly sampled for the study while purposive sampling technique was used in selecting 10 key informants for interviews. The study area was in Kipkelion West Sub-County within Kericho County in Kenya. Household questionnaires and interview guides were used in the data collection. The validity and reliability for the instruments was determined and adjusted through piloting and triangulation methods. Descriptive statistics was employed and results were then presented in graphs, charts and tables. Findings from the study showed that the main sources of water in Kipkelion West Sub-County were; Rivers and Streams at 48%, Springs at 22%, rain water collection at 17%, piped water at 5%, water vendors at 3%, water piped to dwellings at 2% and wells, ponds, boreholes and dams at 1% each. In addition, the strategies for managing water resources in Kipkelion West Sub-County can be divided into pollution management strategies at 44%, supply and demand management strategies at 25%, scarcity management strategies at 18%, quality management strategies at 9%, and conservation management strategies at 5%. Taken together, there is need to develop new strategies and approaches for managing the available water resources.
Application of GIS on the Identification of Suitable Areas for Water Conservation Technologies in the Upper Tana Watershed of the Central Highlands of Kenya
(IJPSS, 2019) Nganga, B. W.; Nge’tich, K. O.; Adamtey, N.; Milka, K.; Ngetich, K. F.
Low adoption of soil water conservation technologies has been one of the main causes for decreased agricultural productivity in the Upper Tana Catchment of Kenya. Proper identification of locations to scale-out the individual technologies necessary to improve water conservation is a key determinant for the rate of adoption. Our main aim was to identify the suitable sites for water conservation technologies using the suitability model created by the model builder function in ArcGIS 10.5® . The model combined the thematic layers of soil texture, slope, rainfall, and stream order, which were acquired from assorted online sources. The factors were converted to raster format and reclassified based on their suitability and were assigned fixed scores and weights byuse of multi influencing factor (MIF) method. The suitability evaluation was carried out by use of weighted overlay to produce suitability classes for each of the water conservation technique. The delineated suitability maps indicated that check dams are highly suitable in 50% of the study area. Mulching, on the other hand, is highly suitable for 49% of the study area. Zai pits are highly suitable in 43% of the study area. Majority of the study area is moderately suitable for the use of terraces, covering 41% of the study area. The highly suitable areas for the Checkdams are Machakos, Kitui, Tharaka-Nithi and lower parts of Embu. The highly suitable areas for mulching are Kirinyaga, Murang’a, Nyandarua and Nyeri. The highly suitable areas for the Zai pits are Kitui, lower parts of Tharaka-Nithi and the highly suitable areas for the terraces are Murang’a, Nyeri and Kirinyaga. Furthermore, the results demonstrated the effectiveness of GIS in delineating the suitable areas for the use of water conservation technologies.
Assessment of vertical and Horizontal distribution of Meiobenthos Alonga salinity Gradient in the Tana and Sabaki Estuaries, North Coast Kenya
(WIO Journal of Marine Science, 2022) Amisi Joel; Munga Cosmas; Wambiji Nina; Kimani Edward
Abstract Meiobenthos respond to variability in salinity gradients in estuarine habitats and are thus suitable organisms for ecological studies. The vertical and horizontal distribution of the meiofauna community structure of two major estuaries (Sabaki and Tana) on the north coast of Kenya were compared. The aim was to draw a meiofaunal data-set inventory of the two estuaries and to examine how salinity gradient, seasonality and sediment character-istics influence their structure. Replicate samples were collected from three sampling stations along the salinity gradient of each estuary. A total of 3,556 individuals belonging to 26 taxa were recorded. Based on seasons and across stations, the upper surface (0-5 cm) layer recorded the highest meiobenthic density (90 ± 42 ind.10 cm-2),followed by 46 ± 23 ind.10 cm-2 (5-10 cm) and 30 ± 8 ind.10 cm-2 in the deepest sediment layer (10-15 cm) stud-ied. The southeast monsoon season recorded the highest mean density (160 ± 22 ind.10 cm-2) compared to the northeast monsoon season (22 ± 12 ind.10 cm-2) for both estuaries. Results of the non-Metric MultidimensionalScaling technique revealed distinct seasonal composition in meiobenthos but not between the estuaries. Results of the 2-way ANOSIM test confirmed no significant differences in meiobenthic composition between the estuaries(p = 0.712). However, seasonal difference was significant (p = 0.001) with higher densities for nematoda (166 ± 99ind.10 cm-2 and 56 ± 29 ind.10 cm-2) recorded in Tana and Sabaki, respectively during the southeast monsoon season. At least 7 taxa out of a total of 26 were present in both estuaries. Salinity gradient, season and sediment depth were found to influence the meiobenthic densities and taxa composition
A Regional Assessment of Seasonal-to-decadal Changes in estuarine Socio-ecological Systems in the Western Indian Ocean. Published in Western Indian Ocean Journal of Marine Science
(WIO Journal of Marine Science, 2021) Jorge Santos; Johan C. Groeneveld; Fiona MacKay; Cosmas N. Munga
Abstract Estuarine socio-ecological systems (SES) in the Western Indian Ocean (WIO) region face mounting pressures from overexploitation, habitat degradation, impacts of climate change and governance inadequacies. A regional assessment of seasonal-to-decadal change in SES of three estuaries (Bons Sinais in Mozambique, Ruvu in Tanzania and Tana in Kenya) was undertaken along 2000 km of tropical coastline (3°-18°S), using a systems-oriented approach and information collected during the Estuarize-WIO project (2016-2019). All three estuaries were open and tidal, but differed along gradients of geomorphology, annual precipitation, exposure to tropical storms, drought, sea level rise, and rural to urban development. Despite physical differences, similar marine species, mangrove assemblages, seasonality in fish-based farming systems and cultivated crops, and fishing methods were apparent across the region. Key differences were related to the scale of anthropogenic disturbance, discerned from land use / land cover (LULC) change analysis, which showed decadal increases in developed-, cultivated- and grasslands, at the expense of wetlands and forests, and seasonal transformation of wetlands to agriculture and grasslands. The three estuaries represented a gradient along urban-production-conservation dimensions, brought about by rural to urban transformation, and by freshwater and sediment diversion for economic development in upstream catchment areas. Household surveys indicated strongly seasonal livelihood strategies, with highest diversity in peri-urban settings, and reliance on different combinations of ecosystem goods and services in coastal and upstream rural settings. Estuarine fisheries ranged from unselective, low trophic-level fisheries using fine-mesh nets at the urbanized and most-disturbed Bons Sinais Estuary, to a more complex organized fishery at the least-disturbed Tana. At Ruvu, fisheries and agriculture production exit the system to distant markets. The systems-oriented approach demonstrated that human-induced processes affected WIO estuaries and dependent livelihoods more deeply than inherent physical differences. A key conclusion is that research, management and governance will benefit from regional cooperation, given the similarities of the systems and the different levels of disturbance.
Effects of supplemental irrigation on yield, water use efficiency and nitrogen use efficiency of potato grown in mollic Andosols
(Springer Nature, 2021-08-18) Satognon, Felix; Owido, Seth F. O.; Lelei, Joyce J.
Low soil fertility and reduced seasonal rainfall contribute to low potato (Solanum tuberosum L.) yield in Kenya. Nitrogen (N) deficiency is the major problem facing by the smallholder farmers of Kenya due to lack of fallow. Hence an introduction of supplemental irrigation with an adequate application of this nutrient could increase potato yield. The objective of this study was to determine the effects of supplemental irrigation and N-fertilisation on potato tuber yield, water use efficiency (WUE) and nitrogen use efficiency (NUE). The experiment was conducted in Nakuru County, Kenya for two seasons. The experimental soils are classified as mollic Andosols. The treatments comprised two irrigation treatments of full supplemental irrigation (FI) and rainfed production (RF) and four N levels of four N levels of 0 (N0), 60 (N1), 90 (N2) and 130 kg N/ha (N3).ResultsThe results showed that total tuber yield, marketable tuber yield and NUE were significantly (P < 0.001) affected by irrigation × N-fertilisation while WUE was only affected (P < 0.001) by N-fertilisation. The highest total tuber yield, 58.28 tonnes/hectare (t/ha), was recorded under FI combined with N3. Treatment FI significantly increased marketable tuber yield by approximately 125.58% in all N treatments compared to RF. The highest NUE of potato (236.44 kg/kg of N) was obtained under FI combined with N3 but not significantly different from the NUE of potato obtained under FI with N2. N-fertilisation N3 produced the highest WUE of 14.24 kg/m3. Significant correlation was obtained between tuber yield and number of tubers/plant (r = 0.75, P < 0.001), NUE (r = 0.95, P < 0.001) and WUE (r = 0.72, P < 0.001).ConclusionHigh potato yield and marketable tuber yield can be achieved in mollic Andosols when water deficits of the growing season are eliminated with supplemental irrigation and an application of 130 kg N/ha.
Mangrove cover and cover change analysis in the transboundary area of Kenya and Tanzania during 1986–2016
(Taylor & Francis group, 2019-05-20) Mungai, Fredrick; Kairo, James; Mironga, John; Kirui, Bernard; Mangora, Mwita; Koedam, Nico
Mangrove forests are among the most threatened ecosystems on earth. Some of these forests traverse national boundaries complicating their management due to differences in governance structures between countries. To improve the management of transboundary species regular monitoring is essential. Remotely sensed data were used to estimate forest cover and analyze conditions of mangroves in the proposed transboundary conservation area (TBCA) between Kenya and Tanzania. Image analysis was performed using unsupervised and supervised classification methods. The transboundary mangroves cover an estimated 11,906 ha; 55% being in Kenya, 45% in Tanzania. Ceriops tagal, Avicennia marina, and Rhizophora mucronata species co-dominate the mangroves of the transboundary area. The hotspot for loss and degradation of mangrove in the TBCA is Vanga in Kenya with a loss of 27 ha/yr. Harvesting of mangrove wood products have contributed to the loss of mangroves in the transboundary area. TBCA formation could play a critical role in ensuring sustainable mangrove resources utilization.
Effects of Population Growth on Urban Extent and Supply of Water and Sanitation: Case of Nakuru Municipality, Kenya
(Journal of Environmental Management, 2019) Muoria, Elizabeth; Moturi, Wilkister; Eshiamwata, George
Urbanization causes changes in social and environmental conditions with most of these changes impacting on the efficient provision of essential services such as water and sanitation. Nakuru Municipality was observed to be the fastest growing urban area in East and Central Africa. Research on patterns and trends of urban and population increase and their implication on water service provision and sanitation in urban Nakuru is very scanty. This paper presents findings from an assessment of the effects of population growth between 1999 and 2017 on urban extent and supply of water and sewage reticulation in Nakuru municipality and surrounding peri-urban areas. Data was collected through remote sensing and administration of questionnaires to urban Nakuru residents and key informants from NAWASSCO respectively to elicit information on the water supply network and sewerage reticulation in Nakuru municipality for the period 1989-2014. Geographic Information System (GIS) was used to analyze the data on time series. The results indicate that the population of Nakuru municipality and surrounding peri-urban areas has increased by 56.8% whereas that of built-up area has increased by 182.5% in the same period through densification of the urban core and expansion to the peri-urban areas characterized by urban sprawl. The water supply network and sewerage reticulation increased by 236km and 89km respectively within Nakuru municipality. The analysis of the maps shows that water supply network and sewerage reticulation are concentrated in the area around the urban core with very little spread. This means that the residents on the outskirts of Nakuru Municipality are not well served by the water supply network and sewerage reticulation. The study recommends involvement of all stakeholders in urban planning and in the water sector in order to increase water supply network and sewerage reticulation coverage both in the urban and peri-urban areas.
International Journal of Aquatic Science Temporal variation in physico-chemical characteristics, phytoplankton composition and biomass in Lake Solai, Kenya
(International Journal of Aquatic Science, 2019-10-20) Koskei, Eunice; Kotut, Kiplagat; Nyaga, Justine; Oduor, Steve

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