Rain Season Research Articles

Climate Change Vulnerability Assessment in Mangrove-Dependent Communities of Manoka Island, Littoral Region of Cameroon.

This study was conducted on Manoka Island (Littoral Region of Cameroon) with the aim of analyzing climate change vulnerability and local adaptation strategies based on the local community's perceptions and biophysical evidence. We used household surveys, focus group discussions, field observation, GIS, and remote sensing to collect data on variables of exposure, sensitivity, and adaptive capacity. Historical changes in rainfall and temperature, mangrove cover, and the occurrence of extreme climatic events were used as indicators of exposure. Property losses and income structure were used as indicators of sensitivity, while human, natural, social, financial, and physical assets represented adaptive capacity. 89 households were interviewed in the nine settlements of the island. Results show that Manoka Island is experiencing irregular rainfall patterns (with average annual values deviating from the mean by −1.9 to +1.8 mm) and increasing temperature (with annual values deviating from the mean by −1.2 to +3.12). The dynamics of the coastline between 1975 and 2017 using EPR show average setbacks of more than ±3 m/year, with erosion levels varying depending on the period and location. The number of households perceiving extreme climatic events like seasonal variability, flood, and rain storm was higher. From respondents' perception, housing and health are the sectors most affected by climate change. The reported high dependence of households on fishing for income, their overall low livelihood diversification, and their poor access to climate information reported by 65% of respondents portray their poor adaptive capacity. Local response initiatives are ineffective and include among others constructing buildings on stilts and using car wheels to counter the advancement of seawater inland. The study concludes that households on Manoka Island are vulnerable to the impacts of climate change. Income diversification, mangrove reforestation, the development of sustainable supply chains for wood fuel, and sustainable fish smoking devices are the main pathways for adaptation planning in this area.

Reproductive Biology of Ripon Barbel (Labeobarbus Altianalis) In River Kuja-Migori Basin, Kenya

The present study aimed to investigate the reproductive biology of Labeobarbus altianalis from River Kuja-Migori basin, Kenya. This fish species is distributed in most water bodies in the Lake Victoria basin and effluent rivers. Labeobarbus altianalis is susceptible to fishing due to aggregation at the river mouths during reproduction seasons. We conducted a study for 18 months with an objective of determining length at 50% sexual maturity, fecundity, gonadosomatic index, egg size, sex ratio and breeding season of L. altianalis. The results showed that breeding of this fish occurred from March to August and September to November coinciding with longer and shorter rain seasons. Fecundity ranged from 1320-2382 eggs (mean 1552 ± 23.3). There was a strong correlation between fecundity and total length (R2 = 0.994). The mean egg diameter was 1.2 ± 0.007 mm. Mean gonado-somatic index was 5.63 ± 0.34 and 2.24 ± 0.21 for females and males respectively. The length at 50% sexual maturity was estimated to be 16.3 cm and 18 cm total length for males and females respectively. There was no significant difference in sex ratio from the hypothetical 1:1 (χ2, p > 0.05). Females had low fecundity and males attain sexual maturity earlier than females. Results from this study provide important information for managing riverine fishery in the Lake Victoria basin.
 Vol. 9, No. 2, August 2022: 221-228

Dynamic and Thermodynamic Factors Involved in Future Changes in Extreme Summertime Precipitation in Japan Projected by Convection-Permitting Regional Climate Model Simulations

Abstract Dynamic and thermodynamic factors involved in future changes in local-scale short-term extreme summertime precipitation on the mesoscale and hourly time scale in Japan were examined using convection-permitting regional climate model simulations under the representative concentration pathway 8.5 scenario. The change in the dynamic component primarily contributes to the total change in vertically integrated moisture flux convergence over the analysis domain that is located off Okinawa Island, whereas the thermodynamic component is dominant over the analysis domain that is located off Kyushu Island. Differences in the amount of the dynamic and thermodynamic components are noticeable in these two domains. These results are explained by the difference in the vertical profiles of the convergence term, and hence the convergence itself between the two specific domains. A mesoscale low pressure system on the seasonal rain front—termed the baiu front—is a key factor underlying the difference in the magnitudes and vertical profiles of convergence between the two specific domains. In the vicinity of the domain off Okinawa Island, a mesoscale low pressure system on the baiu front enhances low-level convergence in the future climate when compared with the present climate. This atmospheric state is attributable to the location of the baiu front itself, which is located relatively southward in the future climate and is affected by the domain off Okinawa Island. In the domain where the dynamic component is dominant such as the domain off Okinawa Island, the total moisture flux convergence follows a super–Clausius–Clapeyron scaling.

Using a Sensitivity Analysis and Spatial Clustering to Determine Vulnerability to Potentially Toxic Elements in a Semiarid City in Northwest Mexico

The Getis-Ord Gi* statistic clustering technique was used to create a hot spot exposure map using 14 potentially toxic elements (PTEs) found in urban dust samples in a semiarid city in northwest Mexico. The dust distribution and deposition in this city are influenced by the seasonal wind and rain from the North American Monsoon. The spatial clustering patterns of hot spots were used in combination with a sensitivity analysis to determine which variables most influenced the PTE hot spot exposure base map. The hot spots areas (%) were used as indicators of environmental vulnerability, and a final integrated map was selected to represent the highest vulnerability of PTEs with a 99% level of confidence. The results of the sensitivity analysis indicated that the flood zones and pervious and impervious zones were the most sensitive variables due to their weight in the spatial distribution. The hot spot areas were reduced by 60.4% by not considering these variables. The hot spot analysis resulted in an effective tool that allowed the combination of different spatial layers with specific characteristics to determine areas that present greater vulnerability to the distribution of PTEs, with impacts on public and environmental health.

Fanya juu Terraces Improve Maize (Zea mays L.) and Bean (Phaseolus vulgaris L) Grain Yields on Hardsetting Soils of Semi-arid Eastern Kenya

Aims: Fanya juu terraces are constructed by digging a ditch and throwing the soil up-slope with the sole purpose of maintaining an embankment to slow down runoff flow. The effect of the terraces on crop yields along the slope varies with the soil type. The aim of this study was to determine the effect of Fanya juu terraces on maize (Zea mays L.) and bean (Phaseolus vulgaris L.) yields and how these yields differ with slope positions and depth of the ditches.
 Study Design: Split-split plot design with four replications.
 Place and Duration of Study: The trial was established on Luvisols in Mua location, Machakos County in Eastern Kenya at 37o15’E 1o29’S and 37o15’E 1o29’S during both long rain (LR) and short rain (SR) seasons of 2014 and 2015 (February 2014 to March 2015).
 Methodology: Treatments consisted of three ditch depths (60 cm, 30 cm and 0 cm (control)) in the main plots and three cropping systems (maize/bean intercrop, sole maize and sole bean) in the sub plots. Grain yields were compared across the seasons at the upper, middle and lower slope positions of the terraces using analysis of variance and means separated using least significant difference at P≤0.05.
 Results: There were significant differences in maize grain yields in the interactions of ditch depth and slope position (P=0.004) and ditch depth and season (P<0.001). Higher maize yields were realized when ditches were constructed than in the control. Yields increased from the lower to the upper slope position of the terraces with 30 cm ditch by 49.8% and in the 60 cm by 41.6%. Average yields from treatments with 30 cm ditch were significantly higher than from the control but non-significant from those in the 60 cm ditch. Significant differences (P=0.037) in bean grain yields were observed in interactions of ditch depth and slope position. Higher yields were obtained from the lower position of the 30 cm ditch than the middle and upper positions. Significant differences (P=0.033) were also found in interactions of ditch depths, cropping systems and seasons.
 Conclusion: The results indicate that Fanya juu terraces had a significant effect on crop yields on hardsetting soils. The study recommends construction of Fanya juu terraces with a ditch depth of 30 cm and intensive management of the lower slope position for improved maize and bean production on hardsetting soils in marginal areas.

IN-SITU WATER HARVESTING TECHNOLOGIES AND FERTILIZER RATES INCREASE MAIZE AND BEAN YIELDS IN THE SEMI-ARID KATUMANI, KENYA

<p><strong>Background: </strong>Crop production in the arid and semi-arid lands (ASALs) is constrained by erratic rainfall and poor soil fertility. Therefore, climate smart agriculture mechanisms such as <em>in-situ</em> rainwater harvesting technologies and recommended fertilizer rates would be vital for ensuring food security.<strong> Objective</strong>: To evaluate selected <em>in-situ</em> water harvesting technologies and fertilizer rates on soil water content and yield of maize and beans at KALRO Katumani Research Center in Machakos County, Kenya during the 2019 and 2020 short and long rain seasons, respectively. <strong>Methodology:</strong> The experiment was established in a randomized complete block design with a split-split plot arrangement, replicated three times, with <em>in-situ</em> water harvesting technologies comprising of zai pits, ngolo pits, contour furrows and conventional tillage, as the main plots, whereas the split plots were varying rates of fertilizer inputs: Di-ammonium phosphate (DAP), goat manure and control. The split-split plots comprised of maize and beans cropping systems. Soil moisture content was assessed at 4, 8, 12 and 16 weeks after emergence, whilst nutrient uptake, use efficiency and crop yields at physiological maturity. Data was subjected to analysis of variance. <strong>Results: </strong>Soil moisture, maize and beans yields, nutrient uptake and use efficiency were significantly (p<em> </em>≤ 0.05) increased by <em>in-situ</em> water harvesting technologies and fertilizer inputs. Highest soil moisture content was recorded under zai and ngolo pits and lowest in conventional tillage treatments. Ngolo pits recorded higher maize and beans grain yield. Application of DAP fertilizer increased maize and beans grain yield compared to control. Intercropping maize and beans increased grain yield significantly (p<em> </em>≤ 0.05) compared to sole maize and sole beans. <strong>Implications. </strong>There is need for promoting a combination of <em>in-situ</em> rainwater harvesting technologies especially ngolo and zai pits with application of DAP+ manure in semi-arid areas where water is scarce coupled with poor soil fertility. <strong>Conclusion:</strong> Ngolo and zai pits increased soil water retention capacity while application of DAP fertilizer led to increased crop yield and the study therefore recommends their adoption within the study area and extrapolation to areas of similar conditions. </p>

Use of an aridity index to classify season with an application in genetic evaluation of Braunvieh cattle

AbstractOne of the most important aspects of genetic evaluation (GE) is the definition of contemporary groups (CG), commonly defined as animals of the same sex born in the same herd, year and season. The objective of this study was to use an aridity index (AI) to classify season and evaluate the implications on the GE of Braunvieh cattle. A data set with 32 777 and 22 448 birth weight (BW) and weaning weight adjusted to 240 days (WW) records, respectively, was used to compare two methods of classification of climatic seasons to be used in the definition of CG for GE models. The first method considered rain season criterion (RC), and the second method is a proposed classification using an AI. Both methods were compared using two approaches. The first approach examined differences in mixed models using the RC and AI season to select the best model for BW and WW, evaluated by different goodness of fit measures. The second approach considered fitting a GE model including the season classifications into the CG structure. Lower probability values for season effect and better goodness of fit measures were obtained when the season was classified according to the AI. Results showed that although differences are small, the AI allows a better model fitting for live-weight traits than RC and revealed a re-ranking effect on expected progeny differences data. Further analysis with other traits would demonstrate the extended utility of AI indicators to be considered for fitting models under a climatic change environment.

Integrated SWAT-MODFLOW model to study saltwater intrusion in Da Nang coastal city

This study applied an integrated surface water-groundwater (SW-GW) model, SWAT-MODFLOW to study interaction of surface and groundwater than simulate saltwater intrusion at a regional scale in Da Nang coastal city, center of Vietnam. Model components were calibrated and validated using monthly river flow data and hydraulic head data for the 2005-2020 period and showed good agreement with observed data. The results demonstrated that GW-SW exchange in the upstream areas had the most pronounced fluctuation between the wet and dry months under historical conditions. The combined potential impact is that intensive groundwater use may have more immediate effects on river flow than those of climate change, which has important implications for water resources management and supply in the future. The results showed that the total average recharge to groundwater from the rivers was varied from 12046 to 23147 m3/d relative to 50 – 74% of water resources in rain and dry season. Saltwater intrusion intrusion in 2020 is about 100 km2. In the area of Son Tra and Ngu Hanh Son districts, groundwater pumping must be reduced to zero, in some other areas, pumping rate do not exceed 250 to 1000 m3/day with distance to coastline at least 500 to 1400m depends on each area.

Studi Kadar Fosfat (Total, Polifosfat dan Ortofosfat) pada Daerah Aliran Sungai Lamat Kecamatan Muntilan

Studies on phosphate levels (total, polyphosphate, and orthophosphate) have been carried out in the Lamat Muntilan watershed. A detergent is an approach to the amount of waste disposal of various types of phosphate in the Lamat river. High levels of phosphorus cause eutrophication, which can cause various human health problems. This study aims to determine the levels (total, polyphosphate, and orthophosphate) and compared rain and dry season with water quality standards that have been agreed upon nationally as well as theoretical studies on eutrophication pollution. This research uses the UV-Vis Spectrophotometer method by utilizing the interaction of ammonium tartrate and potassium antimonyl tartrate on orthophosphate ions to form phosphomolybdic acid which is then reduced by ascorbic acid to a modern blue color which is proportional to the number of orthophosphate ions. This modern blue color is measured at a wavelength of 880 nm. The result data showed that the average total phosphate levels of river water of 0.240 ppm in the rainy season and 0.204 ppm in the dry season, for polyphosphates were found at 0.032 ppm in the rainy season and 0.064 ppm in the dry season, while orthophosphate 0.051 ppm in the rainy season and 0.101 ppm in the dry season. In the dry and rainy seasons, there were specific differences between them. This level surpassed Peraturan Pemerintah Republik Indonesia Nomor 82 Tahun 2001 about concerning Management of Water Quality and Control of Pollution Water, was not suitable for consumption directly or indirectly specifically for human needs, but if it was used for animals and plants it is still feasible. The level of all phosphate species triggered the formation of eutrophication.

Trader acceptability of African eggplant (Solanum aethiopicum Shum) genotypes and effect of bio‐control treatments on consumer sensory acceptability

SummaryApplication of advanced agronomic practices may affect the sensory attributes of plant products. The study determined the trader physical acceptability of farmer preferred African eggplant (nakati) genotypes (E11, E15 and E16); and later studied the impact of bio‐control treatments; Trichoderma spp (TRI). and Arbuscular Mycorrhizal Fungi (AMF) on consumer sensory appeal of genotypes using standard sensory evaluation methods. The trader acceptability of genotypes based on leaf number, succulence, smoothness, colour, and shininess were significantly different; except for the hard‐textured leaves of E11 (P ≤ 0.05). Leaf appearance (E11) and stalk‐leaf quantity (E15 and E16) were preferred by high‐end and low‐end markets, respectively. Consumer sensory acceptability of bio‐control‐treated samples, above 85% of E15 and E16 was liked based on reduced bitterness (P ≤ 0.05). Using descriptive sensory tastes, results showed that soil bio‐control treatment with TRI during the light rain season significantly improved the palatability of E15 and E16. Therefore, use of TRI during light or dry season improves sensory appeal of nakati.

Urgensi Pelestarian Ekosistem Lingkungan Fisik Pada Destinasi Wisata: Pengalaman dari Kawasan Ekowisata Hutan Mangrove Batu Lumbang, Denpasar, Bali

The purpose of this study is to disclose the importance of preserving the Batu Lumbang mangrove forest in Denpasar, Bali. The mangrove forest is notable for its high biodiversity rate, and it is also become a popular tourist destination at the same time. This study employs convergent parallel mixed-methods data collection, which includes observation, mapping with Google Earth and Landsat 8 satellite imagery, semi-structured interviews with relevant key informants, and a literature review. Afterwards, descriptive techniques are used to analyse the data. The results indicate that the Batu Lumbang mangrove forest has a coverage area of approximately 85.9 Ha, with a rainfall tension of approximately 100 mm/year in the rain season and 60 mm/year in the dry season. Sixteen vegetation species were discovered in the mangrove forest compound, all of which are common in lowland and mangrove ecosystems. There are also 36 species of fauna, the majority of which are bird and avian in nature. Furthermore, changes in land cover indicate a vibrant ecosystem in the Batu Lumbang mangrove forest area. So far, three types of land cover have been identified: mangrove forests, water bodies and the built environment. Mangrove forests remain dominant among these three, accounting for 60.35 %. As a result, it is no wonder that mangroves have become the primary tourist attraction in Batu Lumbang. Some preservation efforts related to tourism activities that can be made based on its ecological value include: establishing a system of visitor management, dealing with waste problems, and spatial management in areas with high biodiversity as a form of rigorous conservation initiative.
 Keywords: preservation, ecosystem, mangrove, tourist destination, batu lumbang.

Dry Matter Production and Carbon Sequestration Potential of Selected Indigenous and Introduced Grasses under Rangeland Ecosystems of South Eastern Kenya

This study determined dry matter production and carbon sequestration potential of three indigenous and two introduced grass species under rangeland ecosystems. The indigenous grasses were: - Masai love grass (Eragrostis superba), Foxtail (Cenchrus ciliaris), Bushrye (Entropogon macrostachyus) and the introduced grasses were: - Boma rhodes and Extozi rhodes. The study was in South eastern rangeland of Kenya and data was collected during peak growing period of short and long rain seasons from established pasture plots. Plant samples (above ground, below ground and litter) were harvested by randomly placing 1m2 quadrats in each plot in triplicate. Soil samples were randomly collected from each plot at a depth of 0-20 cm, air-dried and analysed for carbon content using Chromic acid digestion method from each plot under selected grasses, bulk density was determined. Harvested plant samples were oven-dried for 48 hours to stable mass at 65o C, ground (± 2mm size) and combusted in a muffle furnace at 550oc for 4 hours to determine organic matter concentration. The results revealed that indigenous grasses were 24% higher in dry matter production (17.3 vs 14.0tons/ha) and 23% higher in carbon stock (11.3 vs 9.2 tons) (p<0.05). The implication of the results is that indigenous grasses would offer co benefit of higher dry matter production for livestock feeding and higher carbon sink capacity contributing to minimising emission and global warming potential. This is beneficial to mitigating climate change when increasing ruminant production under often degraded rangeland ecosystems. with this evidence, utilisation of indigenous grass species is highly recommended for sustainable rangeland livestock production supporting increased productivity while minimising carbon emissions.

Changes in observed rainfall and temperature extremes in the Upper Blue Nile Basin of Ethiopia

Ethiopia, a densely populated country with abundant natural resources, is often hit by climate extreme disasters that cause severe damage to life and property every year in one or the other corner. The frequency and intensity of extreme events have increased in the recent decades due to climate change and variability. This study aimed to analyze the changes in observed rainfall and minimum and maximum temperature extremes in the Upper Blue Nile Basin (UBNB) of Ethiopia from 1980 to 2019 periods. The Mann-Kendall (MK) trend test and Theil-Sen's slope estimator were used to estimate annual and seasonal trends. The rainfall and temperature extremes were analyzed using RClimDex, which is a graphical user interface in R software, by selecting ten rainfall and eleven temperature indices. The results showed a positive trend in annual, dry (March–May) and small rain (October–February) seasons rainfall in more than 54% of the stations and a decreasing trend in the main rain (June–September) season rainfall in 65.4% of the stations. Several extreme rainfall indices showed insignificant positive trends in the basin. Although there is a positive trend in extreme rainfall, the number of consecutive wet days (CWD) and the simple daily intensity index (SDII) show insignificant negative trends in most stations. In addition, a warming trend of the annual and seasonal maximum and minimum temperature extreme indices was noted. Overall, the increase in extreme rainfall and a warming trend in the extreme temperature indices indicate signs of climate change in the UBNB. The findings of this study suggests the need for developing climate change adaptation and mitigation strategies in the UBNB.

Impact of climate change on future precipitation amounts, seasonal distribution, and streamflow in the Omo-Gibe basin, Ethiopia

This study projected the impact of climate change on the amount of precipitation, seasonal distribution, and streamflow of the Omo-gibe basin, Ethiopia. Projections of climate change using the results of high-resolution multimodal ensembles from fifteen regional climate models (RCMs) of the Coordinated Regional Climate Reduction Experiment (CORDEX)-Africa were statistically downscaled and bias-adjusted using a quantile mapping approach. Precipitation and temperature were projected under RCP 8.5 and RCP 4.5 emission scenarios. Climate and streamflow projections from a mean ensemble of RCMs in the near future (2025–2050), medium future (2051–2075), and far future (2076–2100) were compared to the reference (1989–2019). Mann-Kendall (MK) trend testing was used to determine if a change is statistically significant and to detect trends in temperature, precipitation, and streamflow. The Soil and Water Assessment Tool (SWAT) hydrological model was used to project the impact of climate change on the streamflow. According to RCP4.5 and RCP8.5, the emission scenarios predicted significant positive (rising) temperature, but significant negative (decreasing) precipitation and streamflow. The average temperature projected increases range from 2.40-3.34 °C under the RCP 4.5 emission scenarios and 2.6–4.54 °C under the RCP 8.5 emission scenarios. Annual average precipitation projected decreases range between 10.77-13.11% under the RCP 4.5 emission scenario, while the RCP 8.5 emission scenarios decrease range between 11.10-13.86% in the rainy summer season (June–August) and the irregular rain season (March–May). Projected annual average streamflow decrease range between 7.08-10.99% under the RCP 4.5 emission scenarios and 10.98–12.88% under the RCP 8.5 emission scenarios. Results on projected temperature increases and reductions in precipitation and streamflow will help to develop effective adaptation measures to reduce the ongoing impacts of climate change and draw up long-term water resource management plans in the river basin. Both the results and the multidisciplinary approach will be vital to irrigation and hydropower project planners.

Water Regulation Ecosystem Services of Multifunctional Landscape Dominated by Monoculture Plantations

Meeting the growing demand for agricultural production while preserving water regulation ecosystem services (WRES) is a challenge. One way to preserve WRES is by adopting multifunctional landscape approach. Hence, the main objective was to evaluate the role of forest patches (FP) in preserving WRES in tropical landscapes dominated by oil palm plantations. The SWAT model was used to evaluate the essential WRES, such as water yield (WYLD), soil water (SW), surface runoff (SURQ), groundwater recharge (GWR), and evapotranspiration (AET). Due to a compaction, soils in monoculture plantation have higher bulk density and lower porosity and water retention, which decrease WRES. Conserving FP among oil palms evidently improves WRES, such as decreasing SURQ and rain season WYLD and increasing GWR, SW, AET, and dry season WLYD. FP has sponge-like properties by storing water to increase water availability, and pump-like properties by evaporating water to stabilize the microclimate. Mature oil palm also has pump-like properties to maintain productivity. However, it does not have sponge-like properties that make water use more significant than the stored water. Consequently, a multifunctional landscape could enhance WRES of forest patches and synergize it with provisioning ecosystem services of oil palm plantations.

Contrasting tourism regimes due to the COVID-19 lockdown reveal varied genomic toxicity in a tropical beach in the Southern Atlantic.

Tourist occupancy in coastal environments threatens the stability of various coastal ecosystems and is thus a cause for concern for the environmental sector. As such, it is important to perform environmental monitoring in a way that analyses and quantifies the environmental impact of coastal ecosystems. Porto de Galinhas beach (Pernambuco – Brazil) has one of the highest visitation rates in Brazil and suffered from restrictions to human mobility due to the COVID-19 pandemic. These restrictions allowed for the evaluation of the impact of tourism on Porto de Galinhas beach and the effects that the lack of tourist occupancy had during the lockdown period of 2020. Blood samples from the species Abudefduf saxatilis were collected monthly over a period of 1 year and during the lockdown quarter, in order to perform micronucleus (MN) and nuclear morphological alteration (NMA) tests, and data were analyzed at a seasonal level (dry/rainy period) using a comet assay. For the control group, A. saxatilis samples were collected in an environmentally protected area on Tamandaré beach (68 km from Porto de Galinhas). The MN and NMA tests showed a greater frequency of genomic damage when there was greater tourist flow. In relation to rain seasonality, the comet assay showed a greater incidence of genomic damage during the dry period, where there was a higher rate of tourist migration, compared to the rainy period. The lockdown period presented a lower incidence of genotoxic damage compared to the period without restrictions on human mobility and the control. The results show that tourism has been causing a significant environmental impact on Porto de Galinhas beach. The data collected during the lockdown period demonstrated how the absence of human movement results in changes that are favorable to environmental recuperation, as illustrated by the lower frequency of genomic damage.

The effect of climatic factors on the number of malaria cases in an inland and a coastal setting from 2011 to 2017 in the equatorial rain forest of Cameroon

BackgroundWeather fluctuation affects the incidence of malaria through a network of causuative pathays. Globally, human activities have ultered weather conditions over time, and consequently the number of malaria cases. This study aimed at determining the influence of humidity, temperature and rainfall on malaria incidence in an inland (Muyuka) and a coastal (Tiko) settings for a period of seven years (2011–2017) as well as predict the number of malaria cases two years after (2018 and 2019).MethodsMalaria data for Muyuka Health District (MHD) and Tiko Health District (THD) were obtained from the Regional Delegation of Public Health and Tiko District Health service respectively. Climate data for MHD was obtained from the Regional Delegation of Transport while that of THD was gotten from Cameroon Development Coorporation. Spearman rank correlation was used to investigate the relationship between number of malaria cases and the weather variables and the simple seasonal model was used to forecast the number of malaria cases for 2018 and 2019.ResultsThe mean monthly rainfall, temperature and relative humidity for MHD were 200.38 mm, 27.050C, 82.35% and THD were 207.36 mm, 27.57 °C and 84.32% respectively, with a total number of malaria cases of 56,745 and 40,160. In MHD, mean yearly humidity strongly correlated negatively with number of malaria cases (r = − 0.811, p = 0.027) but in THD, a moderate negative yearly correlation was observed (r = − 0.595, p = 0.159). In THD, the mean seasonal temperature moderately correlated (r = 0.599, p = 0.024) positively with the number of malaria cases, whereas MHD had a very weak negative correlation (r = − 0.174, p = 0.551). Likewise mean seasonal rainfall in THD moderately correlated (r = − 0.559, p = 0.038) negatively with malaria cases, contrary to MHD which showed a very weak positive correlation (r = 0.425, p = 0.130). The simple seasonal model predicted 6,842 malaria cases in Muyuka, for 2018 and same number for 2019, while 3167 cases were observed in 2018 and 2848 in 2019. Also 6,738 cases of malaria were predicted for MHD in 2018 likewise 2019, but 7327 cases were observed in 2018 and 21,735 cases in 2019.ConclusionHumidity is the principal climatic variable that negatively influences malaria cases in MHD, while higher seasonal temperatures and lower seasonal rain fall significantly increase malaria cases in THD.

Assessment of Runoff and Soil Loss Under Natural Vegetation Cover and Rainfall in a Semi-Arid Catchment, West Pokot County, Kenya

Soil erosion has become a major cause of land degradation with regrettable economic losses. It has affected livelihoods of many agro-pastoral communities in Arid and Semi-arid Lands (ASALs). There is need for continuous assessment of soil erosion in these areas in order to provide sufficient data on soil loss for soil resource management, conservation, and land use planning. The purpose of this study was to determine the rate of soil loss by water for soil conservation planning in West Pokot County, Kenya. Two adjacent fields with variable vegetation cover density were identified in a semi-arid catchment for runoff plot research. Vegetation cover on the fields was measured using the transect line-intercept survey method. Field 1 had 25–50% vegetation cover while field 2 had 50–75% vegetation cover. On each field, three identical erosion plots with dimensions 20 m along the slope and 10 m wide were constructed. Runoff and sediment from the plots were measured for fifteen rainfall-runoff events during the long rains season. Data was analysed using correlation analysis and linear regression methods. The results show that runoff production varied from 1.03% to 1.44% of total rain water. Soil loss from the plots was 120.3–155.5 g/ . Runoff-rainfall correlation analysis showed a significant positive relationship (r =0.9609, P<0.05%) with 92.33% variance in runoff production. Soil loss had significant positive relationship with runoff (r =0.9840, P<0.05%) with 96.83% variance in soil loss. The study found that runoff production and soil loss was slow in the field with dense vegetation cover. Studies project an increase in human and livestock populations in semi-arid areas. This points at possible decrease in vegetation cover and increase in the rate of soil loss by water. The study recommends development of a soil conservation and management strategy in the study area.

Assessment of the impacts of landscape patterns on water quality in Trondheim rivers and Fjord, Norway

Abstract Due to the impacts of hydrological and ecological processes on water quality, discharges from upstream catchments have induced significant pollution to the recipients. This study aims to investigate the possible pollution sources from catchments with different types of land use and landscape patterns and develop the relationships between water quality and the catchment hydro-geological and environmental variables. Data from 10 monitoring sites in Trondheim formulated the basis of the case study. Thermotolerant coliform bacteria (TCB) and total phosphorus (TP) were applied as main indicators to represent the water quality in the recipient rivers, streams and in Trondheim Fjord. Based on the GIS-oriented spatial analysis, 15 hydro-geographical and landscape parameters were selected as explanatory variables. Multiple linear regression (MLR) models were developed at catchment and river reach scales to study correlations between the explanatory variables and the response variables, TCB and TP, in rain and snow seasons. The study showed that the spatial landscape patterns resulted in differences in the concentrations of TCB and TP in the recipients. The agricultural land was shown to be the main pollution source, leading to a higher concentration of TP in streams. Buildings, roads, and other impervious areas have induced an increase in both TCB and TP. In contrast, the forest areas, lakes, river density and steep river slopes were shown to have capacity to filter incoming P-rich runoff, thus prevent pollutant conveyance and accumulation in recipients.

Hydrophobic Effect of Soil Stabilization for a Sustainable Subgrade Soil Improvement.

The chemical process of using additives to stabilize soils is to improve soil that lacks strong engineering properties. In particular, the moisture susceptibility of subgrade soil through seasonal rains is still questionable. The presence of water in the construction is the cause of deterioration and premature distress of pavements and their supporting geotechnical structures. In this work, the chemical use of hydrophobic caltite (HC) in various amounts (ranging from 3%, 5%, to 7%) and 5% of cement to enhance laterite soils is investigated. The investigation includes the evaluation of soil properties, such as, unconfined compressive strength (UCS) by curing in air and under water, flexural strength (FS), and California Bearing Ratio (CBR) soaked and unsoaked. The addition of caltite with cement increases the strength characteristics with the UCS values of 2078–2853 kPa during the early curing stages (7th day), and 4688–4876 kPa after 90 days of curing. The added caltite in the cement soil samples shows a reduction index of strength loss underwater with the UCS values of 3196, 3334, and 3751 kPa for caltite cemented soil when compared with cement soil alone. FS results suggest that the inclusion of caltite in cement means that post-peak behavior can be enhanced, reducing the brittleness and increasing the ductility. The successful reaction with soil additives occurred in the curing period of 7 days. In terms of the microstructural analysis, results show that HC with cement reduces the porosity, voids, and cracking of laterite soils. Furthermore, new polymer globules, products from the reaction, appeared on the clay particle surfaces, thereby reducing the water absorption. The addition of hydrophobic-caltite to the soil–cement mixture results in increased strength and reduced water absorption in a soil–cement mix, thus achieving a given strength value.