Correlation between sunshine hours and climatic parameters at four locations in Uganda

One of the most important factors in solar energy production is related to the predictability of sunshine hours. The objective of this study is to assess the correlation between sunshine hours and relative humidity, cloud cover, maximum and minimum temperature, for the purpose of identifying the most appropriate parameter(s) for the prediction of sunshine hours in Uganda. Climatic data for the meteorological stations of Entebbe, Mbarara, Tororo and Makerere, extending over a period of 15 years (1990-2005) was collected from the Department of Meteorology, Kampala. The data set included maximum temperature, minimum temperature, relative humidity at 6 am and at 12 noon, Cloud cover at 6 am and at 12 noon and Sunshine hours. A multiple regression technique was used to assess the correlation between sunshine hours and maximum and minimum temperatures, cloud cover at 6 am and at 12 noon and relative humidity at 6 am and at 12 noon. Results have shown that the availability of sunshine hours can be predicted by the use of maximum and minimum temperatures, relative humidity at 6 am and 12 noon and cloud cover at 6 am and at 12 noon in Uganda, but, principal components and factoraAnalysis have indicated that two parameters, especially relative humidity at noon or 6 am and Maximum temperature are enough to capture the variability of sunshine hours in Uganda

Effet des flux d’eau sur la capacité de rétention des marais Ciranga et Kabamba, Lac Kivu, République Démocratique du Congo

Cette étude a été conduite en vue d’examiner l’effet des flux d’eau sur l’apport des nutriments charriés par les rivières Lwiro et Cirhanyobwa et déterminer ainsi son impact sur l’efficacité de rétention des polluants par les marais Ciranga et Kabamba. Les échantillons d’eaux récoltés dans les rivières et dans les marais ont été analysés pour l’ammonium, les nitrates, les phosphates, l’azote total et le phosphore total suivant les méthodes spectroscopiques standard. Il est ressorti que les variations de l’efficacité de rétention étaient fonction des rivières, des types de nutriments et de la période d’échantillonnage. Dans la rivière Lwiro traversant le marais Ciranga, il a été ainsi observé une variation de la concentration en phosphore total entre 0.45 - 1.1 μmol/L et de 9.36 - 10.58 μmol/L de l’azote total. Par ailleurs, dans la rivière Cirhanyobwa traversant le marais Kabamba, la concentration en phosphore total a varié entre 0.46 - 0.5 μmol/L contre 10.17 - 23.72 μmol/L d’azote total. Une variation du potentiel de rétention des nutriments (phosphore et azote) en fonction du flux d’eau dans les marais de Ciranga et de Kabamba a été observée. Lors du flux élevé (débit élevé), une réduction significative en concentration des nutriments a été observée dans le marais de Ciranga non anthropogénisé que dans le marais de Kabamba (-66.82 μmol/L en phosphore total et -40.97 μmol/L en azote total contre -44.321 μmol/L en Phosphore et un gain de 21.885 μmol/L d’azote total). Des mesures de restauration des marais seraient d’une grande importance pour la stabilité du Lac Kivu et d’autres écosystèmes importants de la région.Mots-clés: flux, rétention, nutriment, marais, lac Kivu. Effect of water discharge on pollutant retention efficiency in Ciranga and Kabamba wetlands, Lake Kivu, Democratic Republic of CongoThis study was conducted to examine the effect of water discharge on nutrients transported by Lwiro and Cirhanyobwa rivers and to determine its impact of the retention efficiency of pollutants by the Ciranga and Kabamba wetlands. Ammonium, nitrate, total nitrogen, phosphate and total phosphorus were analyzed using standards spectroscopic method. Results show that variations of the pollutant retention efficiency were function of rivers, nutrients types and the sampling period. In the river Lwiro crossing Ciranga wetland, total phosphorus concentration ranged between 0.45 and 1.1 μmol/L and between 9.36 and 10.58 μmole/L of total nitrogen. Moreover, in the river Cirhanyobwa crossing the Kabamba wetland, the total phosphorus concentration varied between 0.46 to 0.5 μmol/L against 10.17 to 23.72 μmol/L of total nitrogen. Pollutant retention efficiency varied with water discharge. During the high flux (high discharge flux), significant reduction of nutrients concentration was observed in Ciranga, a no intensively used for anthropogenic activities than in Kabamba wetland which is intensively used for anthropogenic activities (-66.82 μmol/L for total phosphorus and -40.97 μmol/L for total nitrogen for Ciranga against -44.321 μmol/L of total phosphorus and a increased of 21.885 μmole/L of total nitrogen for Kabamba). In order to stabilize Lake Kivu and other important ecosystems of the region, there is need some restoration measures of wetlands.Keywords : fluxes, retention, nutrient, wetlands, lake Kivu

Sediment and nutrient loads into river Lwiro, in the Lake Kivu basin, Democratic Republic of Congo

This study assessed sediment and nutrient loads in Lwiro river, Lake Kivu basin in the Democratic Republic of Congo. Water discharge was measured and water samples were collected twice a month from 6 sites in Lwiro river system and analyzed for total suspended sediment (SS), temperature, pH, dissolved oxygen (DO), chemical oxygen demand (COD), five-day biological oxygen demand (BOD5), alkalinity and nutrients (P, N, PO43-, NO3- and NH4+) using standard methods. Results show that the concentration of BOD5 was low (1.08 ± 0.83 mg/L); but COD (13.13 ± 6.26 mg/L) and SS (1.15 ± 0.36 mg/L) were high in the industrial effluent than in agricultural effluent (2.7 ± 0.77 mg/L for BOD5; 9.05 ± 3.55 mg/L for COD and 0.81 ± 0.36 mg/L for TSS). It was observed that all these values were low compared to the standard limit proposed by UNECE and Uganda standard. TSS, nutrient and other chemicals parameters load analyzed were high in agriculture effluent than in industrial effluent except for NH4+ load. Temporal variation and site difference between TSS and nutrient load were significantly different (F=5.54, p< 0.005 for SS; F= 8.59, p< 0.005 for TP and F=7.63, p< 0.005 for TN). Techniques for reducing nutrient and TSS loads should be initiated in the microcatchment to protect the Lake Kivu.Keywords: Sediment; nutrient load; industrial; agriculture effluent; Lwiro river; Lake Kivu

High-spectral-resolution Fabry-Perot interferometers overcome fundamental limitations of present volcanic gas remote sensing techniques

Remote sensing (RS) of volcanic gases has become a central tool for studying volcanic activity. For instance, ultraviolet (UV) skylight spectroscopy with grating spectrographs (GS) enables SO2 (and, under favourable conditions, BrO) quantification in volcanic plumes from autonomous platforms at safe distances. These measurements can serve volcanic monitoring and they cover all stages of volcanic activity in long measurement time series, which substantially contributes to the refinement of theories on volcanic degassing. Infrared (IR) remote sensing techniques are able to measure further volcanic gases (e.g., HF, HCl, CO2, CO). However, the employed Fourier transform spectrometers (FTSs) are intrinsically intricate and, due to limited resolving power or light throughput, mostly rely on either lamps, direct sun, or hot lava as light source, usually limiting measurements to individual field campaigns. We show that many limitations of grating spectrographs and Fourier transform spectrometer measurements can be overcome by Fabry-Perot interferometer (FPI) based spectrograph implementations. Compared to grating spectrographs and Fourier transform spectrometers, Fabry-Perot interferometer spectrographs reach a 1-3 orders of magnitude higher spectral resolution and superior light throughput with compact and stable set-ups. This leads to 1) enhanced sensitivity and selectivity of the spectral trace gas detection, 2) enables the measurement of so far undetected volcanic plume constituents [e.g., hydroxyl (OH) or sulfanyl (SH)], and 3) extends the range of gases that can be measured continuously using the sky as light source. Here, we present measurements with a shoe-box-size Fabry-Perot interferometer spectrograph (resolving power of ca. 150000), performed in the crater of Nyiragongo volcano. By analysing the light of a ultraviolet light emitting diode that is sent through the hot gas emission of an active lava flow, we reach an OH detection limit of about 20 ppb, which is orders of magnitude lower than the mixing ratios predicted by high-temperature chemical models. Furthermore, we introduce example calculations that demonstrate the feasibility of skylight-based remote sensing of HF and HCl in the short-wave infrared with Fabry-Perot interferometer spectrographs, which opens the path to continuous monitoring and data acquisition during all stages of volcanic activity. This is only one among many further potential applications of remote sensing of volcanic gases with high spectral resolution

Benefits and drivers of farm mechanisation in Ruzizi Plain, Eastern Democratic Republic of Congo

Farm mechanisation plays a major role in the agricultural sector, as it facilitates achievement of energy-intensive operations. In developing countries, policies and technical constraints have greatly affected the development of a coherent agricultural mechanisation system, that is accessible to farmers, especially the poorest. This study aimed to identify the socioeconomic factors that have driven the use of different sources of farm power in family farming in Ruzizi Plain in Democratic Republic of Congo. A random sample of 190 smallholder farmers and 30 technicians were surveyed in 2014 and 2015 in six areas of Kamanyola, Luvungi, Luberizi, Sange, Kiringye and Kiliba. Results showed that mechanisation in the Ruzizi Plain involved a range of sources of farm power, including draft animals, tractors and rototillers. Factors such as gender, attitude of the head of a household, farm productivity and profitability and non-farm incomes played a crucial role in the choice of whether or not to mechanise. Maize profitability was higher under mechanisation (US$535.46 ha-1) compared to non-user farms (US$ 7.73 ha-1). For cassava, however, there were no significant differences in profitability between mechanised and non-mechanised farms. Other benefits of mechanisation included better working conditions, reduction in the duration of farming operations, and the expansion of cultivated land parcels.La m\ue9canisation agricole joue un r\uf4le majeur dans le secteur agricole, car elle facilite l\u2018aboutissement d\u2018op\ue9rations \ue0 forte intensit\ue9 \ue9nerg\ue9tique. Dans \ua0les pays sous-d\ue9velopp\ue9s, les politiques et les contraintes techniques ont fortement affect\ue9 le d\ue9veloppement d\u2019un syst\ue8me de m\ue9canisation agricole coh\ue9rent, accessible aux agriculteurs, en particulier aux plus pauvres. Cette \ue9tude visait \ue0 identifier les facteurs socio\ue9conomiques qui ont conduit \ue0 l\u2019utilisation de diff\ue9rentes sources d\u2019\ue9nergie agricole dans l\u2019agriculture familiale dans la plaine de Ruzizi en R\ue9publique d\ue9mocratique du Congo. Un \ue9chantillon al\ue9atoire de 190 petits exploitants et 30 techniciens a \ue9t\ue9 interrog\ue9 en 2014 et 2015 dans six zones de Kamanyola, Luvungi, Luberizi, Sange, Kiringye et Kiliba. Les r\ue9sultats ont montr\ue9 que la m\ue9canisation dans la plaine de Ruzizi impliquait une gamme de sources d\u2019\ue9nergie agricole, y compris les animaux de trait, les tracteurs et les motoculteurs. Des facteurs tels que le sexe, l\u2019attitude du chef de m\ue9nage, la productivit\ue9 et la rentabilit\ue9 agricoles et les revenus non agricoles ont jou\ue9 un r\uf4le crucial dans le choix de m\ue9caniser ou non. La rentabilit\ue9 du ma\uefs \ue9tait plus \ue9lev\ue9e sous m\ue9canisation (US$535.46 ha-1) par rapport aux exploitations non utilisatrices (US$ 7.73 ha-1). Pour le manioc, cependant, il n\u2019y avait pas de diff\ue9rences significatives de rentabilit\ue9 entre les exploitations m\ue9canis\ue9es et non m\ue9canis\ue9es. Les autres avantages de la m\ue9canisation comprenaient de meilleures conditions de travail, la r\ue9duction de la dur\ue9e des op\ue9rations agricoles et l\u2019expansion des parcelles de terres cultiv\ue9es

Contribution of ‘human induced fires’ to forest and savanna land conversion dynamics in the Luki Biosphere Reserve landscape, western Democratic Republic of Congo

peer reviewedHuman-induced fire is one of the most important determinants of forest cover and change in tropical and subtropical regions of the world. Yet its impact on forest cover and forest cover change remains unclear, as fires in Africa generally do not spread over very large area. This is particularly the case in the Democratic Republic of Congo (DRC), a region of the world that is still poorly investigated. Here, we propose to study the effect of humaninduced fire on land use and land cover change in a protected area of the DRC, i.e. the Luki Biosphere Reserve (LBR). We investigate tree cover changes in and around the reserve between 2002 and 2019 using Landsat 7 ETM+, Landsat 8 OLI/TIRS and MODIS MCD12Q1 images and quantify human induced fires using MODIS MCD64A1 images. The study combines land use and land cover (LULC) change detection analysis of four images, two acquired in 2002 and two acquired in 2019, with multi-temporal assessment of annual burnt area acquired between 2002 and 2019 from MODIS MCD64A1 to assess the role of fire in LULC changes and the sensitivity of different LULC types to fire. The results show a dynamic conversion of primary forest to secondary forest over about 16% of the area, the evolution of savanna to secondary forest over 9.6% (Landsat image) and the replacement of secondary forest by savanna over 8.1% (MODIS image) of the total area of Luki Reserve. Of the total area undergoing land use change, 34.1% (Landsat image) and 35.7% (MODIS image) were caused by fire, which however did not cause a significant LULC change. For the LULC types that experienced fire events, the least stable type was KEYWORD

Réponse du soja (Glycine max L.) à des doses croissantes du DAP et Urée au Sud-Kivu, RD Congo

Published online: 28 Feb 2018; Open Access JournalObjectif: La présente étude a été menée pour évaluer la réponse du soja à des doses croissantes du DAP et de l’Urée dans les conditions édapho-climatiques de Bugorhe dans les hautes altitudes du Sud-Kivu. Méthodologie et résultats: Une expérimentation a été conduite suivant un dispositif en parcelle divisée (split plot) avec la source d’engrais azoté et la dose d’application des engrais comme facteur principal et facteur secondaire respectivement. Trois doses de l’Urée et du Di-Ammonium Phosphate (DAP) ont été appliquées à raison de 50 kg ha-1 (D1), 100 kg ha-1 (D2) et 150 kg ha-1 (D3) et une dose témoin D0 (sans engrais). Le rendement en graines variait significativement en fonction de la dose (p=0,0015) et de la nature (source) d’engrais azoté (p=0,0199). Le DAP avait permis d’obtenir le rendement le plus élevé (1158,1 kg ha-1) comparativement à l’Urée (956,7 kg ha-1). Quant aux doses d’engrais, le rendement variait proportionnellement avec la dose d’engrais appliquée : la D3 (150 kg ha-1) du DAP a donné une moyenne élevée de rendement en graines (1640,9 kg ha-1) alors que la dose témoin a donné une faible moyenne de rendement en graines (694,1 kg ha-1). Pour l’Urée, la dose D3 avait permis d’obtenir le rendement en graines le plus élevé (1229,8 kg ha-1) comparativement à la dose témoin (627,4 kg ha-1). Le rapport valeur sur coût obtenu sur les différentes doses d’engrais montre que la dose de 50 kg ha-1 de l’Urée et 100 kg ha-1 du DAP sont plus rentables avec des valeurs de 3,53 USD (4987,89 francs congolais) et 4,23 USD (5976,99 francs congolais). L’efficacité agronomique des doses d’engrais a varié entre 4,01 et 6,31 pour la dose 150 kg ha-1 de l'Urée et du DAP. Conclusion et application des résultats: Les résultats montrent que la dose de 150 kg ha-1 pour le DAP et l’Urée permettrait d’améliorer le rendement en graines du soja au Sud Kivu mais, n’est pas rentable. Cependant, les doses de 50 kg ha-1 et 100 kg ha-1 de l’Urée et DAP sont à encourager le plus au vue de leurs rentabilités. Mots-clés: Soja, Engrais azoté, Productivité, Rentabilité économique, Bugorhe, RD Congo English Title: Response of the soybean (Glycine max L.) to increasing doses of DAP and Urea in the South – Kivu, DR Congo English Abstract Objective: This study assessed the soybean response to increasing doses of Di-Ammonium Phosphate (DAP) and Urea in the agro-ecological conditions of Bugorhe located in the highlands of South – Kivu. Methodology and results: A field experiment was carried out in a split plot design with the fertilizer source as main factor and fertilizer dose as the sub-factor. Three doses of Urea and DAP were applied: 50 kg ha-1 (D1), 100 kg ha-1 (D2) and 150 kg ha-1 (D3) and a Control (D0) without fertilizer. The soybean grain yield varied significantly with the applied dose (p=0.0015) and the nitrogen fertilizer source (p=0.0199). The DAP application recorded the highest grain yield (1158.1 kg ha-1) compared to Urea (956.7 kg ha-1). Regarding to fertilizer doses, the grain yield varied proportionally with fertilizer dose applied: D3 (150 kg ha-1) of DAP gave the highest grain yield (1640.9 kg ha-1) compared to control, which had the lowest grain yield (694.1 kg ha-1). For Urea, the D3 dose gave the highest grain yield (1229.8 kg ha-1) compared to control D0 (627.4 kg ha-1) which recorded the lowest grain yield. The value cost ratio obtained for different doses of fertilizer showed that the dose of 50 kg.ha-1 of Urea and 100 kg ha-1 of DAP were more profitable with 3.53 USD (4987.89 Congolese francs) and 4.23 USD (5976.99 Congolese francs) of economic benefits, respectively. The agronomic efficiency (AE) of fertilizer doses was varying from 4.01 to 6 31 for 150 kg ha-1 of Urea and 150kg ha-1 of DAP. Conclusion and result applications: Results showed that the D3 dose (150 kg ha-1) of DAP and Urea would improve soybean grain yield in South – Kivu but, is not profitable. However, doses of 50 kg ha-1 and 100 kg ha-1 of Urea and DAP should be encouraged for their expected profit

Recent Activity of Nyiragongo (Democratic Republic of Congo): New Insights From Field Observations and Numerical Modeling

Nyiragongo volcano is known for its active lava lake and for socioeconomic issues arising from future possible eruptive events having major impacts on the community living in the Virunga region. The 2020 field expedition inside the summit crater has allowed the collection of unprecedented field observations to state on the current activity. Since the February 2016 intracrater event, the crater floor level has been rising much faster than during the 2010–2016 period. The current activity is reminiscent of the 1970–1972 and 1994–1995 periods preceding the lava lake drainage events in 1977 and 2002. Numerical simulations, successfully validated with data over the past 30 years, show that the rising of the crater floor could slow down in the next months/years and reach a critical equilibrium. Based on the past eruptive history and on the current activity, a flank eruption in the March 2024 to November 2027 interval could be a possible scenario