Intergrated Water Resources Management

Permanent URI for this collection

https://repository.nrf.go.ke/handle/123456789/23

Browse

Now showing 1 - 20 of 165

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.
A Test of the Applicability of the Lake Habitat Survey for Hydromorphological Monitoring of a Tropical Alkaline Lake (Simbi) with a Fisheries Potential
(International Journal of Fisheries and Aquatic Studies, 2019-09) Opiyo, Stephen; Getabu, Albert Mochache; Sitoki, Lewis Morara; Shitandi, Anakalo
The Lake Habitat Survey (LHS) is an ecological integrity monitoring tool developed for temperate lakes by an independent team of researchers to support the implementation of the EU Water Framework Directive (WFD). It has been widely applied but more testing is needed in different settings, therefore this study investigated the applicability of the LHS protocol in assessing the habitat quality of a tropical alkaline lake in the face of increasing impacts of anthropogenic pressure and climate change. The LHS metrics of Lake Habitat Quality Assessment (LHQA) and Lake Habitat Modification Score (LHMS) estimated for Lake Simbi collectively suggested that the physical habitat quality of the lake is moderate since its hydromorphology is moderately modified. In conclusion, LHS is effective for monitoring ecological condition of water bodies to inform decision making for conservation and management hence it is suitable for adoption in Kenya and the tropics as one of the standard tools for lake environmental assessments.
Access and utilization of Information resources and services by Water specialists in Kenya: The case of the Ministry of Water and Irrigation
(Moi University, 2019) Kariuki, Alice Wanjiru
Enabling technologies have led to the transformation of libraries and informationcenters‘ collection & services from the traditional prints to e-collections such as e-books, e-journals and other virtual reference services. This has been necessitated bythe environment of increasing economic pressure, rapid shifts in the behaviors andexpectations of the patrons and evolving patterns of scholarly publishing. Thechanges have exerted pressure on libraries and more on the parent institutions in theprovision of the necessary infrastructure and the actual access to e-resources. Thepressure on libraries is in the sourcing, acquisition, repackaging and the provision ofnecessary guidance to end users. Underutilization of these resources may lead to userapathy and affect funding. The aim of the study was to investigate the access and useof e-journals by students and academic staff at USIU and propose strategies forimprovement. The objectives of the study were to: identify the types of e-journaldatabases available in the library; determine the frequency of access and use of e-journals by users; establish the policies in place for governing access to and use of e-journals; examine the level of information and computer literacy skills among userson their access and use of e-journals; establish the degree of awareness of theavailability of e-journals; identify major inhibitors to access and use of e-journals,and suggest measures to enhance access to and use of e-journals. The study wasguided by the Unified Theory of Acceptance and Use of Technology Model byVenkatesh, et al (2003). The study adopted mixed method approach. Stratifiedrandom sampling, simple random sampling and purposive sampling techniques wereused to collect data from students and academic staff. Questionnaires and semi-structured interviews were used to collect data from 202 respondents constituting 186students, 16 academic staff and 4 informants from the library. Collected data wasintegrated, presented and analyzed using qualitative and quantitative techniques ofnarratives and numerical. The major findings of the study were: USIU library has avariety of online research databases hosting online journals that are not adequate andcurrent in meeting the ever-changing information needs of users; the frequency ofaccessing e-journals is relatively low with most users accessing them occasionally;the level of awareness of e-journals and their use is low among the library clientele asmost of them do not go through training prior to access and use e-journals; libraryusers are challenged in their access and use of e-journals by restrictions via InternetProtocol (IP) addresses and slow internet speeds. The study recommends that:librarians develops and offer orientation and training programmes regularly; offercurrent awareness on e-resources; acquire and make available peer reviewed e-journals in support of education and research to meet their needs and institutionalbandwidth bundle as well as providing computer literacy program to cater for lowskill users. The librarians to develop promotional strategies that is blended, integratesand coordinates all communications channels.
Adaptation to climate change impacts on crop water requirements in Kikafu Catchment Tanzania
(Journal of Water and Climate Change, 2017) Rotich, Stella; Mulungu, Deogratias
Agricultural activities are the main livelihood for about 70% of Tanzania’s population, with women being the main players. Crops need water (crop water requirements, CWRs) for their growth and production, which can either be rain-fed or irrigation sourced. However, climate change has affected the hydrological cycle, particularly water available for agricultural crops. Since impacts and consequently adaptation are site-specific, an assessment of the effects of climate change on maize water requirements in Kikafu sub-catchment was conducted using a crop simulation model, CROPWAT. Accordingly, climate scenarios were obtained from A2 emission scenario using three general circulation models (GCMs). These scenarios were downscaled at two site locations using the Long Ashton Research Station Weather Generator (LARS-WG) model. The baseline period for the change analysis was 1971–2000. The CWRs are projected to increase by 3.8% in the 2020s and 7.1% in the 2050s at the Moshi Airport and 19.9 and 22.4% at Lyamungu station, respectively. More impact is projected to be during 70–80 days of the development stage and the entire mid-season (81–140 days) whereby the temperature will be high but with low precipitation. With the increasing CWRs, better adaptation measures are increase crop diversification, restore soil organic matter and change cropping systems as established through the multi-criteria analysis.
An Assessment of Ground Water Quality in Yatta Plateau in Kitui County, Kenya
(2017-03-21) Mwamati, Fredrick T.
The study is primarily an assessment of groundwater quality in the Yatta Plateau of Kitui County. The study focused on the spatial temporal distribution of key chemical parameters namely pH, TDS, Colour, Total hardness, Turbidity, Conductivity, Total alkalinity, Fluoride and Iron. Yatta Plateau is a volcanic formation which is characteristically flat at the top thus limiting overland flow and depression storage necessary for other methods of water supply to the community resident on the Plateau. Surface water sources are therefore not readily available as most of the rain water percolates easily owing to the flat nature of the plateau. The development of groundwater sources has therefore taken preference to other sources of water supply in the study area. Reliable and good quality water supply on the Yatta Plateau corridor may be affected by the type of chemicals found in the ground water, concentration of the dissolved minerals or even ground water quality changes over time. The purpose of this study was therefore to determine the variability or changes on ground water quality in Yatta Plateau in relation to rainfall, land use, geology among others and determine how the same influences water utilization. Groundwater samples were collected in boreholes distributed on the plateau and the key physicochemical parameters were measured using standard methods . These were then analyzed in order to determine the variability of groundwater quality on the Yatta plateau, the extent of influences of the groundwater chemical parameters on water utilization and, finally come u p with recommendations on the appropriate ways of addressing groundwater quality degradation. The study is also important in that the findings provide a better understanding of possible changes in groundwater quality over time and this will prompt planning for appropriate treatment that is required to address the quality changes. The samples were collected in the period between March 2015 and March 2016 covering two dry seasons and two wet seasons experienced in the study area. Samples were collected four t imes from each of the six target boreholes. In total, twenty four (24) water samples were collected for analysis. The samples were analyzed at the Water Resources Management Authority (WARMA) Water Quality Testing Laboratory in Nairobi. The data obtained f rom the laboratory tests was analyzed using Surfer for spatial - temporal analysis, and were also subjected to Statistical analysis using SPSS (Statistical Package for Social Science). A questionnaire was also administered on the users of water derived from the sampled boreholes. The questionnaires were analyzed using various statistical methods including the analysis of variance (ANOVA), correlation analysis, and regression analysis, test of hypothesis, frequency distribution tables, means, percentages and b ar charts. The results of the study show that there is no direct relationship between rainfall and variations of groundwater quality in the Yatta plateau. It was however found that there was spatial - temporal variability in different groundwater quality parameters that were analysed. The spatial - temporal variability was attributed to differences in the geologic formations forming the aquifers of individual boreholes that were sampled within the study area. Although the groundwater is generally of good quality, electrical conductivity, TDS and fluoride were found to be increasing drastically and may surpass the WHO and KEBS drinking water standards in future. The increase in the parameters was attributed to the nature of the geological formations common on the plateau. The results of the analysis of the questionnaires showed that groundwater chemical parameters do not influence water utilization in the Yatta Plateau. The major water quality concern was taste and this was attributed to salinity. The study provide s recommendations to governmental and non - governmental institutions that are mandated with the responsibility of ground water development planning and quality monitoring.
An Assessment of the Spatial and Temporal variations of Groundwater quality in Yatta Plateau in Kitui County, Kenya
(IISTE, 2017) Mwamati, Fredrick T.; Kitheka, Johnson U.; Njuru, Peter G.
The study is primarily focused on the assessment of groundwater quality in the Yatta Plateau of Kitui County. The study focused on the spatial temporal distribution of key chemical parameters namely pH, TDS, Colour, Total hardness, Turbidity, Conductivity, Total alkalinity, Fluoride and Iron. Groundwater samples were collected four times from the six target boreholes found on the plateau in the period between March 2015 and March 2016. The sampling programme covered two dry seasons and two wet seasons. Key physicochemical parameters were analysed using standard laboratory methods. The water samples were analyzed at the Water Resources Management Authority (WARMA) Water Quality Testing Laboratory in Nairobi. The results of the study show that there is no direct relationship between rainfall and variations of groundwater quality in the Yatta plateau. The influence of water abstraction on water quality was also limited. The dominant influence on groundwater quality in the Yatta Plateau was found to be the geological characteristics of the area. It was however found that there was spatial-temporal variability in different groundwater quality parameters that were analysed. The study recommends integrated groundwater resources management including continuous water quality monitoring in the Yatta Plateau in Eastern Kenya.
Analysis of spatial and temporal drought variability in a tropical river basin using Palmer Drought Severity Index (PDSI)
(Acadamic Journals, 2017-08-31) Wambua, Raphael; Mutua, Benedict; Raude, James
Analysis of spatial and temporal drought variability in the upper Tana River basin using Palmer Drought Severity Index (PDSI) was conducted. The drought is critical for formulation of mitigation measures in the river basin. A monthly temporal and 90-m spatial resolution was applied. This was achieved within ArcGIS environment. Climatic data for 1970 to 2010 was used for computation of the PDSI while the missing data sets were filled using Artificial Neural Networks (ANNs). The results of PDSI for dry and wet seasons at meteorological stations indicate that the time series plots for the PDSI values for dry season are generally lower than those for the wet seasons. The PDSI values for meteorological stations located at the lower elevation of the basin are lower than those located at higher elevation. On the other hand, spatially distributed drought severity based on PDSI show that the ranges of maximum and minimum drought severity values in 1970 are -0.868 to -0.804 and -0.675 to -0.610 respectively. These values of drought severity occur respectively in the north-western and south-eastern areas of the basin. PDSI values increased from the range -0.675 to -0.610 in 1970 and from -1.087 to 0.957 in 2010 for the north-eastern areas of the upper basin. The south eastern areas of the basin are more prone to drought risks than north-western parts. Use of the PDSI reflects the spatial heterogeneity and temporal variability of drought across the basin. The drought assessment offer technical approach for comprehensive understanding of drought for effective drought-induced disaster mitigation and its management, with a view to reducing adverse effects on livelihoods.
Application of Artificial Neural Network Model In Forecasting Water Demand: Case of Kimilili Water Supply Scheme, Kenya
(SSRG International Journal of Civil Engineering, 2019-09-25) Shilehwa, Celsus; Makhanu, Sibilike K; Khaemba, Alex
otable water treatment and supply systems are designed and constructed to deliver adequate amounts of water to meet consumer demand requirements, consequently water demand forecasting is essential for design and operations management of treated water supply systems. Correct prediction of time varying water demand trends and the critical water demand values determines the extent to which a network can satisfy critical demand and maintain economic efficiency. The aim of this study was to forecast Kimilili water supply scheme water demand up to 2030. Kimilili water supply scheme being operated by Nzoia Water Services Company Limited is characterized of rapidly increasing water demand leading to persistent water supply shortages hence unplanned fluctuations in the system water production hours. Artificial Neural Network (ANN) model was utilized to forecast Kimilili water supply scheme water demand. The trained model had good performance with a coefficient of determination (R2) of 0.999972988. The results indicated that Water demand for Kimilili water supply was increasing with time and the general relationship between time and water demand was defined by a sixth order polynomial function given by y = 9e-0x6-1e-05x5+0.0005x4-0.0115x3+0.1178x2+0.1384x+100.48. The study confirmed that ANN can simulate the water demand characteristics of the water supply very well
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.
Application of GIS-Based Spatially Distributed Hydrologic Model in Integrated Watershed Management:A Case Study of Nzoia Basin, Kenya
(Research Gate, 2010) Nyadawa, M. O.; Karanja, F.; Njoroge, T.; Otuoma, Sanya
The overall objective of this study was to study the impact of change of land use / land cover on catchment runoff response using FEWS-Flood Model as the rainfall-runoff conversion model in Nzoia basin, Kenya. Land use / land cover grid data were processed for the years 1986 and 2000 in IDRISI Kilimanjaro environment while both soil data and necessary meteorological data inputs were processed in necessary formats in ArcView. The study revealed that loss of forest cover between the year 1986 and 2000 equaled gain in acreage under cropland land/ woodland mosaic in the same period. Analysis of impact of change of land use/ land cover between 1986 and 2000 also revealed increased peaks in resulting hydrographs as a result of increased acreage under crops and reduced forest cover for same storm characteristics. This has given a rationale to recent increased flood disaster in the basin. Key Words: Nzoia, Integrated watershed management, USGS SFM, land use, land cover
Application Of Hydrological Models In Poorly Gauged Watersheds: A Review Of The Usage Of The Soil And Water Assessment Tool (SWAT) In Kenya
(International Journal of Scientific & Technology Research, 2017-08)
In water-scarce developing countries, river basins are some of the most valued natural resources, but many are poorly gauged and have incomplete hydrological and climate records. In the recent years, tropical rivers are increasingly becoming erratic, with many hydrologists attributing this variability to combined effects of landscape-specific anthropogenic activities and climate change. Uncertainties about the impacts of climate change compound the challenges attributed to poor and often inconsistent river monitoring data. Under data-scarce conditions and with the increasing land use intensification and urbanization, modelling approaches become a useful tool in planning and management of water resources. In this paper, we review the application and usability of the Soil and Water Assessment Tool (SWAT) model in conventional planning practice in the management of water resources is poorly-gauged tropical watersheds of Kenya. We assess the technical implications of the model in Interg
Assessing the Impact of Rainwater HarvestingRainwater harvestingTechnology as Adaptation Strategy for Rural Communities in Makueni County, KenyaMakueni County
(SpringerLink, 2015) Kalungu, Jokastah Wanzuu; Filho, Walter Leal; Mbuge, Duncan Onyango; Cheruiyot, Hillary Kibet
Rainfall scarcity is a constraint to productivity in arid and semiarid regions of Kenya. This chapter identifies the common rainwater harvesting technologies used in Makueni County, a semiarid region, both for domestic and agriculture production as a way of adapting to climate change and variability. Household interviews were held for 134 households from five villages in addition to collection of secondary data from the area. The results revealed that 30 % of farmers have water tanks in their home, 90 % are members of communal sand dams and ponds, while 70 % use road water harvesting to supplement rain-fed agriculture. The constraints for adoption included lack of labor and skills. Different coping strategies applied by small-scale farmers who practice rain-fed agricultural production in this region include soil moisture retention practices such as terracing and use of sand dams as well as storage of water for domestic use in tanks. This valuable information will provide best home-grown practices and reveal gaps on rainwater harvesting which can be implemented by extension officers and local stakeholders. The adoption of these important technologies can be a basis of curbing related problems under similar conditions.
Assessment of effects of deforestation on spring’s water production: A case study of Nuu/Mutaitho Hills Springs in Kitui County
(South Eastern Kenya University, 2017-11-02) Mwia, Rose Catherine
This study is focused on the assessment of the effects of deforestation on springs found in Nuu and Mutaitho hills in Kitui County. Deforestation is manifested by clearing of dry land forests on a massive scale. Springs in Nuu and Mutaitho hills originate from groundwater aquifers and are essentially formed on hillsides and valley bottoms that intersect groundwater flow at or below the local water table. The main objective of the study was to determine the main causes of decline in spring discharges in Nuu and Mutaitho Hills catchment. This was achieved through establishment of the relationship between spring discharges, rate of deforestation, and rainfall variability. The study also involved determination of the impacts of decreasing spring discharges and examination of the perceptions of the local communities on the causes of decline in spring discharges. The study methodology involved collection of data in the field using questionnaires and field based observations. Field data was supplemented with data that was obtained from archival sources e.g spring discharges and rainfall data. The data was analyzed using the Statistical Package for the Social Sciences (SPSS), Geographical Information system (GIS) and various statistical tools in Microsoft Excel package. The result of the study shows that annual rainfall is showing significant variation while the spring discharges over the years has been decreasing drastically. Springs discharge is decreasing at a rate of 30%. Rainfall variability in the study area has changed within the study time from 800mm/year to around 700mm/year. The LANDSAT data showed that the forest /vegetation cover has decreased by almost 40% as the forest in 1963 was at 10% and the current forest cover is about 6% within the study area. The main cause of the decrease of the forest cover from the study is mainly anthropogenic activities. The study recommends more awareness campaign focusing on conservation of the Nuu hills forests and enforcement of regulations focused on the protecting forest resources.
Assessment of organochlorine pesticides (OCPs) contamination in relation to physico-chemical parameters in the Upper River Kuja Catchment, Kenya (East Africa)
(International Journal of Fisheries and Aquatic Studies, 2018-12) Nyaundi, J. K.; Getabu, A. M.; Kengara, F.; Onchieku, J.; Njiru, M.; Kinaro, Z. O.; Babu, J. M.; Sitoki, L. M.; Nyamweya, C.; Osoro, E. M.
Concentrations of 17 organochlorine pesticides residues (alpha-HCH, beta-HCH, gamma-HCH, deltaHCH, Heptachlor, Aldrin, Endrin, Endosulfan I, Dieldrin, p,p’-DDT, Endosulfan II, p,p’-DDD, Endrin aldehyde, p,p’-DDE, Endosulfan sulfate, Heptachlor epoxide and Methoxychlor) were analysed in water and sediment from Upper River Kuja catchment, Kenya, between January-October 2015, using GasChromatography (GC) with (GC-ECD) equipment. Nutrient levels and water quality parameters: pH (7.57±0.354), secchi disk (0.05±0.019), dissolved oxygen (DO) (6.96±0.897), temperature (25.39±2.201), conductivity (62.03±23.123) and hardness (26.39±6.063) contributed to significant variations in organochlorine pesticide residue levels observed. Statistical significance differences (p<0.05) between water quality parameters in the sampling stations occurred. Pesticide concentrations ranged within BDL – 0.263µgl-1 , for Heptachlor, BDL – 0.506 µgl-1 Heptachlor epoxide, BDL – 0.506 Aldrin, BDL – 0.014 Dieldrin, p,p’-DDT, BDL – 0.644 p,p’-DDE, BDL – 0.176 p,p’-DDD, and BDL – 2.220 methoxychlor. Sediment pesticide residues were higher during rainy period. Results indicate persistent organic pollutants (POPs) exist in our environment, and recent use in sampled area. Increased aquatic monitoring is recommended to detect persistency and changes in target environment.
Assessment of rain water harvesting technologies for improved food security in Kauwi Sub-Location, Kitui County
(Editon Consortium, 2022-11-10) Koreeny, Modvine; Felista Ng, Ang; Ndung’u, Charles
The study aimed at studying the factors that influence the utilization of specific rainwater harvesting technologies in Kauwi sub-location, Kitui County. The study adopted a survey design. Random sampling was used to identify the villages and households systematically sampled to be interviewed. The target population was 1600 households, 10 per cent of the target population was obtained to get the representative sample size of 160. Kauwi Sub- Location was clustered into 23 villages and 50 per cent of the villages were then randomly selected for the purpose of the study. The results revealed that social-economic factors such as level of education, membership to farmers’ group, access to credit, age, gender and the type of soil influenced the utilization of the technologies. Smallholder farmers need awareness of the various technologies in order to maximize on its utilization. The findings shall help farmers in prioritizing factors that influence decisions on utilizing technologies and policymakers in developing agricultural policies. The study recommended that the government should shift focus on more public participation rather than state involvement in awareness creation on investment of rainwater harvesting technologies in arid and semi-arid lands so as to increase acceptance of the technologies hence increase agricultural productivity thus improving food security. The households’ heads should be educated about farmers groups and their importance in gaining information and its ability in enabling them to access credit hence will enable them in investing in various suitable and sustainable rainwater harvesting 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
Assessment of Water Flow and Sedimentation Processes in Irrigation Schemes for Decision-Support Tool Development: A Case Review for the Chókwè Irrigation Scheme, Mozambique
(AgriEngineering, 2019-03-06) de Sousa, Lateiro Salvador; Wambua, Raphael Muli; Raude, James Messo; Mutua, Benedict Mwavu
Water flow and sedimentation processes have been significantly erratic at the Chókwè Irrigation Scheme (CIS) and have affected its hydraulic performance. Given its expansion there is need to understand these processes taking place on-site and along the channels of the scheme. CIS being the biggest project of its kind in Mozambique requires proper management of water flow and sedimentation processes. Therefore, the effect of water flow, sediment transport and deposition parameters on the performance of the CIS is needed. In order to determine the effect of spatial and temporal water flow and sediment distribution trends along the irrigation canals, there is need to establish a correlation between these parameters. Determining the influence of water flow velocity on sediment settling rate at different depths along the canal reaches is important in managing the CIS. In addition, a developed decision-support tool to predict sediment deposition is required. For this reason, it is therefore crucial to carry out a timely assessment of water flow and sedimentation processes in CIS in a review concept. From the current review, some gaps that exist for more focused research on Chókwè Irrigation Scheme have been identified. In this regard therefore, there is need to develop an effective support tool for managing water flow and sediment deposition along the canal reaches with a view to increasing crop production in CIS.
Belowground Influence of Rhizobium Inoculant and Water Hyacinth Composts on Yellow Bean Infested by Aphis fabae and Colletotrichum lindemuthianum under Field Conditions
(Canadian Center of Science and Education, 2016-04-22) Naluyange, Victoria; Ochieno, Dennis; Wandahwa, Philip; Odendo, Martins; Maingi, John; Amoding, Alice; Ombori, Omwoyo; Mukaminega, Dative; Muoma, John
Rhizobium inoculant has been developed for bean production in Lake Victoria basin. Two types of compost have been developed, water hyacinth compost with cattle manure culture (H+CMC) or with effective microbes (H+EM). Influence of Rhizobium and composts on Aphis fabae and Colletotrichum lindemuthianum were investigated in the field. Rhizobium and hyacinth composts increased nodulation (×2 to 5); while Aphis fabae population increased (×2) on Rhizobium-inoculated plants with H+EM. Incidence of C. lindemuthianum was high in Rhizobium-inoculated plants. Plants that received diammonium phosphate (DAP) fertilizer had few nodules, reduced germination, slow growth and low yields. In conclusion, the water hyacinth composts contain beneficial microbes that promote root nodulation by Rhizobium, which is necessary for nitrogen fixation, while enhancing tolerance to aboveground infestations by A. fabae and C. lindemuthianum. We raise questions on our results to stimulate research, considering that bean breeding programs in Africa have mainly focused on microbial pathogens, and not insect pests.
Characteristic Relationships between Phosphorous Accrual, Ecosystem Aspects and Water Level Fluctuations in Tropical Lakes: Naivasha Ramsar Site, Kenya
(Scientific Research, 2021-01) Obegi, Beatrice; Ogendi, George; Omondi, Reuben; Jomo, Boston; Morara, George; Rindoria, Nehemiah; Orina, Sagwe
Hydrological dynamics affect water levels and thus affecting ecosystem structure and functions. Lake levels in tropical ecosystems affect phosphorous input through runoff from adjacent watersheds. The resultant biological community, water and sediment quality of the lakes due to water level changes is a reflection of the geology of the area and the anthropogenic activities in the watershed. The study conducted between January 2018 and December 2019 was to explore relationships between the phosphorous input and Water Level Fluctuations (WLF) recorded by Water Resource Authority (WRA). Lake water samples were analyzed in the laboratory for phosphorous using molybdenum blue-ascorbic method and recorded using spectrophotometer. Chlorophyll-a was determined by extracting a filtered sample with 15 ml acetone and incubating overnight and thereafter read using a double beam spectrophotometer. Total Suspended Solids (TSS) was determined by filtering 200 ml of a water sample and dried overnight at 105°C. The lowest and highest phosphorous concentrations recorded were 0.2 mg/l and 0.42 mg/l at NST7 and NST2, respectively. Measurements of Chlorophyll-a were 0.32 mg/l and 0.42 mg/l at NST9 and NST2, respectively. Secchi transparency measurements were 32.9 cm at NST3 and 84 cm at NST1. The highest and lowest TSS concentrations were 0.14 mg/l and 0.13 mg/l at NTS1 and NST8, respectively. The hydrodynamic regime in most tropical lakes plays a significant role in the re-reaction of phosphorous that consequently influences productivity. Tropical lakes have extreme lake level fluctuations which accelerate the production process. The influence of water level changes on aquatic productivity is crucial in most tropical lakes and should be taken into consideration when assessing the environmental impacts.
Characterization of anthropogenic activities influencing surface water quality along molo river ecological system, Kenya
(Ethiopian Journal of Environmental Studies & Management, 2017-12-13) Ogendi, G.M.; Moturi, W.M.; Kibitok, N.K.
Surface water is progressively subjected to stress as a result of anthropogenic activities. Systematic observation and characterization of anthropogenic activities along Molo River was done in 2014 to evaluate their effects on surface water quality. Portable GPS receiver was used to identify geographic locations of 23 sites purposively selected; based on their relative positions to the point of anthropogenic activities and included a reference located in the upper reaches. An observation schedule was used to collect data during dry and rainy-season. Chemical parameters were determined by spectrophotometry using standard methods and physical parameters measured in-situ using Wisenschafflich-Technische Werkstätten and pen type Dist 3 Model Meter probes. Data were analyzed using descriptive and inferential statistics. The frequency of occurrence and percentages were computed. Analysis of variance (ANOVA) was used to analyze mean concentrations of various physical-chemical parameters and various sampling occasions. Maximum NO2 was (45.42±3.4 mg∙L−1), NO3 (44.1±0.1 mg∙L−1), SRP 50.25±0.4, DO2 was 0.3±0.0 mg∙L−1, conductivity (616±1.4 μS/cm), and TDS 405.8±8.1 mg∙L−1 while NH4-N 79.69±1.2 mg∙L−1, TN 109.36±09 mg∙L−1, pH was 12.525±8.0 and T ºC 21.4±0.2 ºC. Mean TP was 13.21±1.78 mgL-1 and 2.43±1.70 mgL-1 highly significant at p<0.05 i.e. p= 0.0001. Results indicate that there were significant differences in the means of NO2-N, NO3-N, NH4-N, TN, DO, EC, T°C, and TDS (p=0.0038, 0.0001, 0.0001, 0.0001, 0.0001, 0.0001, 0.0021, and 0.0001) respectively. Observed activities comprised urban-construction/dumping of waste adjacent to riparian-buffer-zones recording 18.4%, domestic animals watered at the river 28.09%, people crossing river using vehicle/motorbikes and/or on-foot 39.2%, children playing in the river 12.9%,water abstraction 11.9%, sand harvesting/quarrying 0.16%, septic tanks-leaks, waste discharged into the river 4% and Washing linen 4.4%.. Washing vehicle/cars/motorbike was highest at the site denoted M3, recording 265 observations. Frequency and intensity of human activities closely relate the results on physical-chemical parameters, interference from direct human activity than natural phenomenon explains the finding. The river water is unsuitable for human consumption.

Browse

Browsing Intergrated Water Resources Management by Title

Results Per Page

Sort Options