Artificial Rainfall Simulator Research Articles

Effects of herbaceous vegetation coverage and rainfall intensity on splash characteristics in northern China

The splash erosion characteristics of the herbaceous-dominant area in northern China remain uncertain. A total of 21 plots (3-m wide × 3-m long) were installed to investigate splash characteristics under different vegetation coverages (0%, 5%, 10%, 20%, 40%, 60%, and 80%) and rainfall intensities (40, 80, and 120 mm/h) using an artificial simulated rainfall device and an improved splash tray. Splashed particles were collected and analyzed for mass and size distribution. This study demonstrated that a vegetation coverage of 40% would help protect soil from splash erosion. Total splash amount generally decreased exponentially with increasing vegetation coverage and splash distance, but rose with increasing rainfall intensity. Vegetation coverage played a more important role in the mass-weighted average splash distance, with a significant Pearson correlation of −0.934 (p ˂ 0.01), compared to the rainfall intensity, with no significant correlation (p > 0.05). Moreover, splashed particles were finer than the original soil matrix because finer soil particles (clay, fine silt, and coarse silt) were transported preferentially by raindrops, and almost all mean weight diameters were lower than that of the soil matrix. Coarse silt showed the largest mass percentage at all splashed distances relative to the least mass percentage of coarse sand. The mass percentages of clay, fine silt, and coarse silt were generally positively correlated with vegetation coverage and splash distance and negatively correlated with rainfall intensity (p ˂ 0.05). Furthermore, the opposite was true for fine and coarse sand (p ˂ 0.05). These results could facilitate the further understanding of splash erosion characteristics and provide some suggestions for erosion control practices in northern China where herbaceous plants are important ingredients.

Experimental study on influence of vegetation coverage on runoff in wind-water erosion crisscross region

Using artificial rainfall simulation method, 23 simulation experiments were carried out in water-wind erosion crisscross region in order to analyze the influence of vegetation coverage on runoff and sediment yield. The experimental plots are standard plots with a length of 20m, width of 5m and slope of 15 degrees. The simulation experiments were conducted in different vegetation coverage experimental plots based on three different rainfall intensities. According to the experimental observation data, the influence of vegetation coverage on runoff and infiltration was analyzed. Vegetation coverage has a significant impact on runoff, and the higher the vegetation coverage is, the smaller the runoff is. Under the condition of 0.6mm/min rainfall intensity, the runoff volume from the experimental plot with 18% vegetation coverage was 1.2 times of the runoff from the experimental with 30% vegetation coverage. What’s more, the difference of runoff is more obvious in higher rainfall intensity. If the rainfall intensity reaches 1.32mm/min, the runoff from the experimental plot with 11% vegetation coverage is about 2 times as large as the runoff from the experimental plot with 53%vegetation coverage. Under the condition of small rainfall intensity, the starting time of runoff in the experimental plot with higher vegetation coverage is later than that in the experimental plot with low vegetation coverage. However, under the condition of heavy rainfall intensity, there is no obvious difference in the beginning time of runoff. In addition, the higher the vegetation coverage is, the deeper the rainfall infiltration depth is.The results can provide reference for ecological construction carried out in wind erosion crisscross region with serious soil erosion.

Effects of rainfall intensity and slope gradient on runoff and sediment yield characteristics of bare loess soil.

Soil erosion is a universal phenomenon on the Loess Plateau but it exhibits complex and typical mechanism which makes it difficult to understand soil loss laws on slopes. We design artificial simulated rainfall experiments including six rainfall intensities (45, 60, 75, 90, 105, 120mm/h) and five slopes (5°, 10°, 15°, 20°, 25°) to reveal the fundamental changing trends of runoff and sediment yield on bare loess soil. Here, we show that the runoff yield within the initial 15min increased rapidly and its trend gradually became stable. Trends of sediment yield under different rainfall intensities are various. The linear correlation between runoff and rainfall intensity is obvious for different slopes, but the correlations between sediment yield and rainfall intensity are weak. Runoff and sediment yield on the slope surface both presents an increasing trend when the rainfall intensity increases from 45mm/h to 120mm/h, but the increasing trend of runoff yield is higher than that of sediment yield. The sediment yield also has an overall increasing trend when the slope changes from 5° to 25°, but the trend of runoff yield is not obvious. Our results may provide data support and underlying insights needed to guide the management of soil conservation planning on the Loess Plateau.

The first flush effect of different urban underlying surfaces through artificial simulated rainfall

Three kinds of underlying surfaces: asphalt road, impervious tiles and grassland at Chang’an University in south second ring road of Xi’an were chosen as testing sites. Self-made device was used to moderate rainfall with different raining conditions: uniform rainfall intensity of 0.3mm/min, 0.5mm/min, 1.0mm/min; front peak type rainfall and back peak type rainfall. The pollutants in the runoff were measured, that included TN, TP, NO3--N, NO2--N, NH4+-N, PO43--P and PN M(V) curves and MFF30 values were analysed to drew these conclusions: under uniform rainfall intensity of 0.3mm/min, 0.5mm/min, 1.0mm/min, the mean values of MFF30 from asphalt road runoff were 0.47, 0.42, 0.41, the mean values of MFF30 from watertight tiles runoff were 0.40, 0.39, 0.38, the mean values of MFF30 from grassland runoff were 0.33, 0.34, 0.32. The first flush magnitude decreased with the increasing of rainfall intensity on asphalt road and watertight tiles, while the first flush intensity first increased and then decreased with the increasing of rainfall intensity on grassland. The mean values of MFF30 from the front peak type rainfall were larger than that from the back peak type rainfall on both asphalt road and watertight tile. The mean values of MFF30 from the back peak type rainfall were larger than that from the front peak type rainfall on grass. Grassland should be built around asphalt road and watertight tiles to attenuate first flush effect.

降雨を考慮した積雪荷重の推定方法に関する研究

In February 2014, owing to heavy snowfall in the Kanto-Koshin region, several buildings were severely damaged. A major cause for the damage was the load on building surfaces caused by heavy snow followed by a surcharge load due to the ensuing rainfall. Countries such as the United States and Canada have established standards on snow loads, which also take into account the surcharge load due to rainfall. In contrast, Japan has not adopted such standards, and hence it is imperative to establish a method for calculating loads added by rainfall to snow loads. Therefore, in this study, experiments were conducted using artificial rainfall on roofs covered with snow to evaluate and propose a calculation method for loads added by rainfall. First, outdoor experiments as well as indoor experiments in a low-temperature experimental facility were conducted. Model roofs with different span lengths and gradients were built and loaded with natural and artificial snow. These model roofs were then treated with rainfall at constant intensity by using an artificial rainfall simulator. The increase in load was measured and several observations were made from the experiments. A smaller roof gradient and larger roof span resulted in a greater peak value of the load added by rainfall. For roofs of the same shape, the peak value of the load added by rainfall increased as the initial snow depth increased. Next, the relationship between surcharge loads due to rainfall and the span length and gradient of the roofs was quantified. The load added by the rainfall was treated as the approximate square root of the snow depth, and a coefficient a, which depends on the span length and gradient of the roof, was defined. However, valuable data were obtained from the experiments for only five types of roof geometries. To estimate the values of the coefficients a for other roof geometries, regression analysis between the coefficient a, roof gradient, and span length was conducted. Comparing the surcharge loads, which were calculated using the estimated coefficients a, with the loads calculated using the O'Rourke equation, a relatively good correspondence between both the results was confirmed. Snow loads that take rainfall into account were obtained for the given regions with corresponding values of the design snow depth. This was achieved by including the load due to rainfall, which is correlated to the snow depth, computed from the proposed formula and the estimated coefficients. In addition, methods that include coefficients reflecting the regional climatic conditions were proposed. One such method is based on the fact that winter rainfall is not always observed during the period when the deepest snow cover occurs. Extreme values of the snow depth were obtained from the meteorological data to derive the ratio of snow loads on rainy days against the maximum winter snow loads; the ratio was treated as the coefficient k1. Another method considers the regional meteorological cases wherein the surcharge load due to rainfall does not reach the peak value. The ratio of the surcharge load value due to such rainfalls against the surcharge load calculated by the proposed formula was treated as the coefficient k2. However, because the influence of coefficient k2 is relatively small, it can be considered as 1 in practice. Moreover, because the impact of loads added by rainfall is relatively small in heavy snowfall regions, the regions where it is necessary to consider the loads due to rainfall may be limited to general regions where the design snow depth is 1 m or less.

云南坡耕地治理水土保持监测方法探索研究

选取水土流失严重的5个治理小流域为研究对象，采用叠加喷洒式模拟降雨控制系统，探索和研究野外人工模拟降雨实验与自然降雨观测相结合的坡耕地水土保持监测方法。分别在5个坡改梯治理小流域内选址建设3个不同坡度20 m × 3 m的实验小区，历时三年进行了59场次模拟降雨实验和汛期158场次自然降雨观测，并分析水土流失治理效益。监测结果表明：坡度和降雨量对坡耕地土壤侵蚀强度影响显著，但降雨量的影响相对更大；模拟降雨实验梯地小区径流系数为坡地小区的39.8%，平均土壤侵蚀强度较坡地小区减小77.7%；自然降雨观测梯地小区径流系数为坡地小区的13.3%，平均土壤侵蚀强度较坡地小区减少90.0%。由此看来，模拟降雨实验和自然降雨观测两种途径的监测结果基本上是一致的，均表明坡改梯后减流减蚀效益显著。 Five small watershed of seriously soil and water loss were selected as case study. The superposition spray type rainfall simulation control system was used to explore artificial simulated rainfall experiment combined with observed rainfall of farmland soil and water conservation monitoring method. Respectively within 5 terrace management of small watershed in the three different slope location construction 20 m × 3 m’s experimental plot, the three-year 59 games simulated rainfall experiment and flood season over 158 natural rainfall observation, used to analyze the benefits of soil and water loss control. The monitoring results show that the slope and rainfall intensity of soil erosion of slope affect significantly, but the influence of the rainfall is relatively greater. Simulated rainfall experiment terrace land plot runoff coefficient of 39.8% of the slope area, average slope area decreases in the soil erosion intensity is 77.7%. Natural rainfall observation terrace land plot runoff coefficient of 13.3% of the slope area, average slope area to reduce in the soil erosion intensity is 90.0%. The simulated rainfall experiment and natural rainfall observation results are basically consistent, which shows that the benefit is remarkable after terrace flow and erosion reduction.

Development of regional pollution export coefficients based on artificial rainfall experiments and its application in North China

The Export Coefficient Model (ECM) has been widely used to estimate nonpoint source (NPS) pollution loads due to its ease of application. Accurate pollution export coefficients are crucial for reducing uncertainties in load estimation. By integrating artificial simulated rainfall experiments with field survey data, we have developed a new method that estimates regional pollution export coefficients. Results showed that the export coefficients calculated using this new method accurately express the regional rainfall–runoff characteristics, as the simulation precision of this method had grown by 30% than the results with traditional ECM and export coefficients which surveyed from the literature. Based on the calculated regional pollutant export coefficient, the annual loads of TN and TP in the plains area of the Baiyangdian basin in 2010 were 25,967.13 t and 4349.29 t, respectively. Among different types of sources, rural livestock had the greatest contribution (over 60%), whereas rural domestic waste represented the smallest contribution (approximately 10%). Of the different sources, pigs contributed almost half of all NPS pollution from livestock, rural residential areas were the main land use pollution source, and rural living garbage was the main source of rural domestic waste. Spatially, NPS was mainly distributed in the Zhulong and Juma watersheds. Other watersheds only contributed approximately 5% NPS per watershed. However, the per-area loads of these lower load watersheds were larger or nearly equal to that of the Zhulong watershed. Therefore, the lower load watersheds should be addressed for the control of NPS pollution.

<sup>15</sup>N isotope tracing of nitrogen runoff loss on red soil sloping uplands under simulated rainfall conditions

Stable isotope 15N tracer technique was used in combination with artificial rainfall simulation to study the influence of interflow and surface-flow on nitrogen (N) migration loss of soil-plant systems on typical red soil sloping uplands. This study also investigated the utilization efficiency of fertilizer N during different peanut plant growth stages. The results indicated that soil N loss was predominantly via interflow and erosive sediment. Fertilizer N loss during the initial growth stage was mainly through surface runoff, while that occurred as interflow increased from less than 5% to around 16% during the middle and late growth stages. The loss of fertilizer N through surface runoff, erosive sediment and interflow accounted for over 18% of the total N application. The utilization rate of fertilizer N by peanut plants was around 45% through its life cycle, and that 70% of N absorbed by this plant derived from the soil. This highlighted the importance of adopting effective methods to reduce nutrient loss through interflow and surface-flow, the need to increase the utilization rate of fertilizers, and the importance to maintain soil fertility at a relatively high level.

Influence of vegetation on runoff and sediment in wind-water erosion crisscross region in the upper Yellow River of China

All characteristics of vegetation, runoff and sediment from 1960 to 2010 in the Xiliu Gully Watershed, which is a representative watershed in wind-water erosion crisscross region in the upper reaches of the Yellow River of China, have been analyzed in this study. Based on the remote sensing image data, and used multi-spectral interpretation method, the characteristics of vegetation variation in the Xiliu Gully Watershed have been analyzed. And the rules of precipitation, runoff and sediment’s changes have been illuminated by using mathematical statistics method. What′s more, the influence mechanism of vegetation on runoff and sediment has been discussed by using the data obtained from artificial rainfall simulation test. The results showed that the main vegetation type was given priority to low coverage, and the area of the low vegetation coverage type was reducing year by year. On the country, the area of the high vegetation coverage type was gradually increasing. In a word, vegetation conditions had got better improved since 2000 when the watershed management project started. The average annual precipitation of the river basin also got slightly increase in 2000–2010. The average annual runoff reduced by 37.5%, and the average annual sediment reduced by 73.9% in the same period. The results of artificial rainfall simulation tests showed that the improvement of vegetation coverage could increase not only soil infiltration but also vegetation evapotranspiration, and then made the rainfall-induced runoff production decrease. Vegetation root system could increases the resistance ability of soil to erosion, and vegetation aboveground part could reduce raindrop kinetic energy and splash soil erosion. Therefore, with the increase of vegetation coverage, the rainfall-induced sediment could decrease.

The effect of slope length on sediment yield by rainfall impact under different land use types

To evaluate the impact of slope length on sediment yield under different rainfall intensities and land use types on low hill gentle slope, the characteristics of sediment yield process were analyzed based on the field artificial rainfall simulation. For the study, grassland and capsicum slope were taken from Anji county of Zhejiang province, China. Results indicated that rainfall intensity had stronger influence than slope length on sediment yield in south region. For capsicum slope, sediment yield increased quickly with increasing slope length when rainfall intensity greater than 90 mm h–1. The slope length had no significant effect on sediment yield when rainfall intensity less than or equaled to 90 mm h–1. For grassland, data from experiments indicated that sediment yield increased slowly with increasing slope length under rainfall intensity less than 120 mm h–1. There was a decreasing tendency of sediment yield at 6 m slope length under all rainfall events. It was concluded from particle size analysis of erosional sediment that silt and clay particles <0.02 mm were always preferentially transported on both capsicum slope (silt 47.1%, clay 40.9%) and grassland (silt 38.3%, clay 35.9%). We hope these results are useful for soil and water conservation and land management.

Soil and water conservation on steep slopes by mulching using rice straw and vetiver grass clippings

This research investigated the performance of mulching using rice straw mulch (RC) and vetiver grass clippings as mulch (VGM) in reducing soil loss and runoff during the early stages of cultivation on an agricultural area. The effects of the rainfall intensity and mulch rate in conserving runoff and trapping sediment were determined by field experiments on land with a steep 30% slope. Three rainfall intensities of 35 mm/h, 65 mm/h and 95 mm/h were applied using an artificial rainfall simulator. The effects of five mulch rates (1.0, 1.5, 2.5, 5.0 and 7.5 t/ha) with conventional tillage were compared with un-mulched treatment. Both VGM and RC showed good potential for reducing runoff and soil loss. For a given rainfall intensity of 65 mm/h and a mulch rate of 1.5 t/ha, RC reduced runoff and soil loss less than VGM. For higher mulch rates, RC performed better than VGM. For example, at the 5.0 t/ha mulch rate, RC reduced runoff and soil loss by about 47.5% and 62.9%, respectively, compared to VGM with a corresponding reduction of 42.4% and 53.7%, respectively. It is recommended that application of 5.0 t/ha of RC or 7.5 t/ha of VGM is the most suitable for soil and water conservation.

Effects of Rainfall Intensity and Slope Gradient on Runoff and Soil Moisture Content on Different Growing Stages of Spring Maize

The rainfall-runoff process (RRP) is an important part of hydrologic process. There is an effective measure to study RRP through artificial rainfall simulation. This paper describes a study on three growing stages (jointing stage, tasseling stage, and mature stage) of spring maize in which simulated rainfall events were used to study the effects of various factors (rainfall intensity and slope gradient) on the RRP. The RRP was tested with three different rainfall intensities (0.67, 1.00, and 1.67 mm/min) and subjected to three different slopes (5°, 15°, and 20°) so as to study RRP characteristics in semiarid regions. Regression analysis was used to study the results of this test. The following key results were obtained: (1) With the increase in rainfall intensity and slope, the increasing relationship with rainfall duration, overland flow, and cumulative runoff, respectively, complied with logarithmic and quadratic functions before reaching stable runoff in each growing stage of spring maize; (2) The runoff coefficient increased with the increase in rainfall intensity and slope in each growing stages of spring maize. The relationship between runoff coefficient, slope, rainfall intensity, rainfall duration, antecedent soil moisture, and vegetation coverage was multivariate and nonlinear; (3) The runoff lag time decreased with the increase in rainfall intensity and slope within the same growing stage. In addition, the relationship between runoff lag time, slope, rainfall intensity, antecedent soil moisture, and vegetation coverage could also be expressed by a multivariate nonlinear equation; (4) The descent rate of soil infiltration rate curve increased with the increased rainfall intensity and slope in the same growing stage. Furthermore, by comparing the Kostiakov, Horton, and Philip models, it was found that the Horton infiltration model was the best for estimating soil infiltration rate and cumulative infiltration under the condition of test.

Relationship between soil surface roughness and hydraulic roughness coefficient on sloping farmland

The soil surface roughness and hydraulic roughness coefficient are important hydraulic resistance characteristic parameters. Precisely estimating the hydraulic roughness coefficient is important to understanding mechanisms of overland flow. Four tillage practices, including cropland raking, artificial hoeing, artificial digging, and straight slopes, were considered based on the local agricultural conditions to simulate different values of soil surface roughness in the Loess Plateau. The objective of this study was to investigate the relationship between the soil surface roughness and hydraulic roughness coefficient on sloping farmland using artificial rainfall simulation. On a slope with a gradient of 10°, a significant logarithmic function was developed between the soil surface roughness and Manning's roughness coefficient, and an exponential function was derived to describe the relationship between the soil surface roughness and Reynolds number. On the slope with a gradient of 15°, a significant power function was developed to reflect the relationship between the soil surface roughness and Manning's roughness coefficient, and a linear function was derived to relate the soil surface roughness to the Reynolds number. These findings can provide alternative ways to estimate the hydraulic roughness coefficient for different types of soil surface roughness.

The Characteristics of Runoff and Sediment Yield in Different Land Use Types in Southwest Mountains of Henan Province

By indoor artificial rainfall simulator and slope plot test, the regularity of runoff and sediment yield of five types top soil— timber forest, shrubby grassland, terrace, slope cropland and waste-grassland under six kinds of rainfall intensity were studied in Danjiangkou Reservoir on southwest mountains of Henan Province to provide a scientific basis for comprehensive control of regional soil and water loss, to ensure the safety of water quality in the reservoir. The conclusions were that: (1) Land use types had less influence on the runoff comparing to sediment yield. (2) Sediment yield had obvious power function relationship with the runoff amount. (3) Bed load took up majority in the sediment yield of farmland soil while the bed load almost equaled to the value of silt load in woodland soil.

Influence of ridge height, row grade, and field slope on soil erosion in contour ridging systems under seepage conditions

Seepage in contour ridge systems is a common phenomenon that can exacerbate soil erosion, however, the characteristics of soil erosion under seepage conditions in contour ridge systems are not clear. The objective of this study was to analyze the soil erosion process under seepage conditions and quantify the effects and interactions between the ridge height, row grade, and field slope on runoff and sediment yield. Twenty-three treatments for these three factors were arranged by an orthogonal rotatable central composite design. A new type of experimental plot for simultaneously changing the row grade and field slope and creating seepage conditions was used to imitate the microtopographic relief of contour ridge systems. In each run, seepage samples from the row sideslope were collected every 2min for 60min, and then artificial rainfall simulation was performed for 30min during which runoff samples were collected every 1min. The results showed that four soil erosion sub-processes were observed, including interrill erosion, headward erosion, contour failure, and rill erosion. Second-order polynomial regression models predicted the sediment yield (R2=0.74) better than the runoff (R2=0.56). Interactions between these factors did not significantly affect the runoff or sediment yield even at p<0.1. The row grade and field slope exerted a greater effect on the sediment yield than on the runoff, whereas the ridge height influenced the runoff more with an increasing positive effect. The effect of these three factors on sediment yield revealed a convex curve with an increasing factor value. The field slope exhibited a greater increasing effect before the maximum sediment yield occurred and a greater decreasing effect after that than the other two factors did. The maximum runoff and sediment yield occurred at similar row grades (7.5° and 7.1°, respectively) and field slopes (10.9° and 10.8°, respectively). However, the minimum runoff occurred at a ridge height of 6.7cm, and the maximum sediment yield at a ridge height of 12cm. The findings have important implications for assessing and modeling soil erosion in contour ridge systems.

Artificial rainfall tests, soil moisture profiles and geoelectrical investigations for the estimation of recharge rates in a semi-arid area (Jordanian Yarmouk River Basin)

To overcome the limitations posed by the limited relevant data for recharge estimation in the Jordanian Yarmouk River basin, a mass balance methodology is developed which is simple and may be easily applied to other arid and semi-arid landscapes. This is done by integrating available climatic data with new rain–runoff relationship data, as measured using a specially designed and built artificial rainfall simulator, and changing soil moisture profiles through the hydrological year, as measured in the field. The amount of moisture in the soil after rainfall events changes as a result of both evaporation and of drainage into deeper levels (recharge). The soil moisture profiles at depth are evaluated using geophysical techniques that allow for the tracking of recharge fronts. After rainfall events, the distribution of its fate between runoff, evaporation and recharge is determined. Water in the soil beyond the field capacity can be demonstrated to mostly contribute to the ultimate groundwater recharge in the area. Water stored beyond the permanent wilting point is not considered to contribute significantly to the recharge regime. Because of the irregular nature of rainfall, the amount of recharge is found to be related to the spacing of wet and dry spells during the winter months more than the actual amount of rainfall. Prolonged dry periods allow for excess water to drain into the deeper soil and thus to the groundwater, and thus allow for more uptake following subsequent rainy events. Evaporation does not significantly contribute to the drying of the soils. Reanalysis of rainfall and evaporation data from previous years suggests that recharge rates range from 20 to 37 % of total rainfall amounts, as opposed to the currently assumed 5 %.

A study of deterioration of reinforced concrete beams under various forms of simulated acid rain attack in the laboratory

This paper studies the behaviour of deteriorated reinforced concrete (RC) beams attacked by various forms of simulated acid rain. An artificial rainfall simulator was firstly designed and evaluated. Eleven RC beams (120 mmx200 mmx1800 mm) were then constructed in the laboratory. Among them, one was acting as a reference beam and the others were subjected to three accelerated corrosion methods, including immersion, wetting-drying, and artificial rainfall methods, to simulate the attack of real acid rain. Acid solutions with pH levels of 1.5 and 2.5 were considered. Next, ultrasonic, scanning electron microscopy (SEM), dynamic, and three-point bending tests were performed to investigate the mechanical properties of concrete and flexural behaviour of the RC beams. It can be concluded that the designed artificial simulator can be effectively used to simulate the real acid rainfall. Both the immersion and wetting-drying methods magnify the effects of the real acid rainfall on the RC beams.

PELINDIAN UNSUR KALIUM (K) DAN NATRIUM (Na) MATERIAL VULKANIK HASIL ERUPSI GUNUNG MERAPI 2010 (Simulasi Laboratorium)

&lt;p&gt;This research was conducted at the Greenhouse Laboratory of the Faculty of Agriculture, Sebelas Maret University Surakarta, in March 2011. The aim of the study was to determine the relationship between the rainfall (synthetic) the number of elements Potassium (K) and Sodium (Na) were leached in volcanic material from the eruption of Mount Merapi. This study used artificial rainfall simulation approach to treatment is based on the phenomenon of the eruption of Mount Merapi, Yogyakarta, Central Java by examining the leaching elements Sodium (Na) and Potassium (K) are swapped in the above-ground volcanic material Andisol. The experiments in this study using a completely randomized design (CRD) consisting of 3 to 5 treatments the sample depth artificial rain (water sprinkling) in 3 replications, namely 1 (22 mm x 1 day (22 mm)), 2 (22 mm x 10 days (220 mm)), 3 (22 mm x 20 days (440 mm)), 4 (22 mm x 30 days (660 mm)), 5 (22 mm x 45 days (990 mm)), and control ( 45 days field) with 3 replicates each. The variables measured were pH H2O, available K and Na, K and Na total, CEC, texture. Analysis of the data using the F test at the level of 95% or Kruskal-Wallis, to compare the mean between treatments using DMR test at the level of 95% or Mood Median, whereas to determine the relationship between variables used correlation test. The results showed that administration of rainfall of 22 mm / day is able to affect the leaching of potassium and sodium in the volcanic material from day 10. Leaching was significantly visible on day 30 with a decrease in available K and Na volcanic material at a depth of 0-15 cm in diameter (K 23.08%) (23.08% Na) and at a depth of 15-30 cm (K 21, 42%) (23.08% Na), and the addition of K and Na are available at a depth of &amp;gt;30 cm in the form of land Andisol (K 16.67%) (23.53% Na) from the previous treatment.&lt;/p&gt;

Soil Moisture Dynamics and Effects on Runoff Generation at Small Hillslope Scale

AbstractSoil moisture variability has a major impact on runoff generation. In this study, the dynamics and variability of soil moisture at small hillslope transects were analyzed by artificial rainfall simulation experiments in which the influence of crop type and slope angle were considered. Soil moisture variability and dynamics during the rainfall-runoff process were monitored by capacitance sensors (EC-5) with high temporal resolution (1 min) and continuously measured after rainfall ceased to investigate soil moisture dynamics and patterns by the method of data visualization. Relationships between soil moisture and runoff (surface and subsurface flow) and response lag times of soil moisture at different slope positions and soil layers were investigated. The dynamics of soil moisture during the entire crop growth stage were also analyzed. Results showed that soil moisture exerted strong influence on runoff generation, but the relationships were strongly affected by crop type. There was an obvious thres...

English

This study aims to analyze the influence of the characteristics of slope erosion rate of the surface layer of silty sand soil cover layer is given with rice straw fiber. This study is testing in the laboratory using a model USLE (Universal Soil Loss Equation) as a comparison to determine the amount of the rate of soil erosion that occurs in silty sand. Research carried out with 3 variations of rainfall intensity is 50 mm/hour, 100 mm/hour and 120 mm/hour and using artificial Rainfall Simulator tool in the Hydroulics Laboratory of State Polytechnic of Ujung Pandang. The physical model used in this study is made of wooden planks shaped box with1x1x0,5 m. The result showed that the effect of rainfall intensity and slope gradient on soil erosion rate is directly proportional. In high rainfall intensity and the greater the value of the slope will increase the magnitude of the rate of soil erosion also. The magnitude of the rate of erosion that occurs based treatment in the laboratory on successive rainfall intensity I50, I100 and I120 with 10˚ slope is E = 4,100 gr/m2/hour, E = 15,350 gr/m²/hour and E = 39,250 gr/m²/hour. At 20˚ slope is E = 5,650 gr/m²/hour, E = 24,800 gr/m²/hour and E = 54,150 gr/m²/hour and slope of 30˚ is E = 35,608 gr/m²/hour, E = 53,500 gr/m²/hour and E = 94,150 gr/m²/hour. Based on the result of the regression analysis on the original land for the determination of the rate of erosion due to changes in rainfall intensity I50, I100 and I120 with a slope of 10˚, 20˚ and 30˚ is obtained: E = 0,8197e0,0311(I), E = 1,1264e0,0318(I) and E = 17,845e0,0128(I). For closing 30% of straw fiber row on I50, I100 and I120 with 10˚ slope is E = 0,750 g/m²/hour, E = 1,050 gr/m²/hour and E = 1,750 gr/m²/hour. At 20˚ slope is E = 2,450 gr/m²/hour, E = 3,050 gr/m²/hour and E = 5,900 gr/m²/hour and slope of 30˚ is E = 6,150 gr/m²/hour, E = 9,400 gr/m²/hour and E = 21,300 gr/m²/hour. Based on the result of the regression analysis for the closure of 30% rice straw fiber is obtained : E = 0,4109e0,0111(I). The magnitude of the rate of erosion that occurred in the percentage cover 30% on average by 17,68% of the rate of erosion on rate native soil, in other words the rate of erosion on native soil will be reduced by an average of 82,932% if the land is given a cover layer of rice straw fiber the percentage cover of 30%.