The necessity to saline and sodic waters is sometimes used for irrigating agricultural activities under certain circumstances, but it is important to note that the use of these waters comes with specific consideration...The necessity to saline and sodic waters is sometimes used for irrigating agricultural activities under certain circumstances, but it is important to note that the use of these waters comes with specific considerations and limitations. One way to decrease undesirable effects of sodic waters on the physical and chemical properties of soils is to apply organic and chemical amendments within the soil. This study aimed to assess the effectiveness of saline water on soil acidity, alkalinity and nutrients leaching in sandy loamy soil at Bella flower farm, in Rwamagana District, Rwanda. The water used was from the Muhazi Lake which is classified as Class I (Saline water quality). Column leaching experiments using treated soils were then conducted under saturated conditions. The soil under experimental was first analyzed for its textural classification, soil properties and is classified as sandy loamy soil. The t-test was taken at 1%, 5% and 10% levels of statistical significance compared to control soil. The results indicated that the application of saline water to soils caused an increase in some soil nutrients like increase of Phosphorus (P), Potassium (K<sup>+</sup>), Magnesium (Mg2<sup>+</sup>), Sulphur (S), CN ratio and Sodium (Na<sup>+</sup>) and decreased soil texture, physical and chemical properties and remained soil nutrients. Consequently, the intensive addition of saline water leachates to soil in PVC pipes led to decreased of soil EC through leaching and a raiser Soluble Sodium Percentage (SSP). The rate of saline water application affected the increase accumulation of SAR and Na% in the top soil layers. The study indicated that saline water is an inefficient amendment for sandy soil with saline water irrigation. The study recommends further studies with similar topic with saline water irrigation, as it accentuated the alkalinity levels.展开更多
Complex processes of sediment transport in a river impact on overall aquatic system and result in the productivity decrease of socio-economic development projects taking the river as a source of water. The present stu...Complex processes of sediment transport in a river impact on overall aquatic system and result in the productivity decrease of socio-economic development projects taking the river as a source of water. The present study was designed to estimate Sebeya river sediment load and assess its impacts on Lake Kivu, Gihira water treatment plant and various hydropower plants constructed in Sebeya catchment located in Western Province of Rwanda. Water samples were hand-collected from five different sampling points along Sebeya river during rainy and dry seasons. Laboratory analysis for turbidity, total suspended solids, sieve analysis for bed load materials and NPK content of water samples were conducted. The results revealed that the average turbidity was found to be high during rainy season compared to dry season. The same trend was found in total suspended solids concentrations. At all 5 sampling sites and during rainy season compared to dry season, the average mass flowrates of bed load materials were 7.84 and 2.96 kg/hr respectively. Sieve analysis results showed that all bed load sediments were mainly composed of high proportions of fine sand of more than 70% which adversely causes damages on hydropower turbines and the effect of high soil erosion rates on Gihira water treatment plant was traduced by high turbidity of raw water and excessive costs of reagents. At Sebeya outlet, nutrients load and high turbidity reduce significantly the aesthetic quality of Lake Kivu, having a harmful impact on recreation and tourism, aquatic life and affect the livelihoods of people living in the vicinity. Researchers recommend two options of reducing the amount of sediment load in Sebeya river: either to prevent soil erosion or to trap eroded sediment at the upstream of the hydropower and the water treatment plants. Assessing the sediment load fluctuations in Sebeya river is useful for water managers and planners to adjust operations accordingly at water treatment and hydropower plants.展开更多
文摘The necessity to saline and sodic waters is sometimes used for irrigating agricultural activities under certain circumstances, but it is important to note that the use of these waters comes with specific considerations and limitations. One way to decrease undesirable effects of sodic waters on the physical and chemical properties of soils is to apply organic and chemical amendments within the soil. This study aimed to assess the effectiveness of saline water on soil acidity, alkalinity and nutrients leaching in sandy loamy soil at Bella flower farm, in Rwamagana District, Rwanda. The water used was from the Muhazi Lake which is classified as Class I (Saline water quality). Column leaching experiments using treated soils were then conducted under saturated conditions. The soil under experimental was first analyzed for its textural classification, soil properties and is classified as sandy loamy soil. The t-test was taken at 1%, 5% and 10% levels of statistical significance compared to control soil. The results indicated that the application of saline water to soils caused an increase in some soil nutrients like increase of Phosphorus (P), Potassium (K<sup>+</sup>), Magnesium (Mg2<sup>+</sup>), Sulphur (S), CN ratio and Sodium (Na<sup>+</sup>) and decreased soil texture, physical and chemical properties and remained soil nutrients. Consequently, the intensive addition of saline water leachates to soil in PVC pipes led to decreased of soil EC through leaching and a raiser Soluble Sodium Percentage (SSP). The rate of saline water application affected the increase accumulation of SAR and Na% in the top soil layers. The study indicated that saline water is an inefficient amendment for sandy soil with saline water irrigation. The study recommends further studies with similar topic with saline water irrigation, as it accentuated the alkalinity levels.
文摘Complex processes of sediment transport in a river impact on overall aquatic system and result in the productivity decrease of socio-economic development projects taking the river as a source of water. The present study was designed to estimate Sebeya river sediment load and assess its impacts on Lake Kivu, Gihira water treatment plant and various hydropower plants constructed in Sebeya catchment located in Western Province of Rwanda. Water samples were hand-collected from five different sampling points along Sebeya river during rainy and dry seasons. Laboratory analysis for turbidity, total suspended solids, sieve analysis for bed load materials and NPK content of water samples were conducted. The results revealed that the average turbidity was found to be high during rainy season compared to dry season. The same trend was found in total suspended solids concentrations. At all 5 sampling sites and during rainy season compared to dry season, the average mass flowrates of bed load materials were 7.84 and 2.96 kg/hr respectively. Sieve analysis results showed that all bed load sediments were mainly composed of high proportions of fine sand of more than 70% which adversely causes damages on hydropower turbines and the effect of high soil erosion rates on Gihira water treatment plant was traduced by high turbidity of raw water and excessive costs of reagents. At Sebeya outlet, nutrients load and high turbidity reduce significantly the aesthetic quality of Lake Kivu, having a harmful impact on recreation and tourism, aquatic life and affect the livelihoods of people living in the vicinity. Researchers recommend two options of reducing the amount of sediment load in Sebeya river: either to prevent soil erosion or to trap eroded sediment at the upstream of the hydropower and the water treatment plants. Assessing the sediment load fluctuations in Sebeya river is useful for water managers and planners to adjust operations accordingly at water treatment and hydropower plants.
