Final Infiltration Rate Research Articles

Evaluation of infiltration rate and pedotransfer function under different landuse patterns for Kalyanpur block, Bihar

The information on the pedotransfer function of soil is vital for crop cultivation planning and management. The present study evaluated the pedotransfer function of ten locations (different villages) in the Kalyanpur block of Bihar state, India. The various soil parameters like soil texture, infiltration rate, soil penetration resistance, Bulk density, porosity, water holding capacity, available water content, field capacity, permanent wilting point, gravimetric moisture content and organic carbon were evaluated. The infiltration rate and soil penetration resistance were measured in the field and other parameters were evaluated in the laboratory with suitable techniques. The observed data of the above parameters were analyzed for given locations. A good coefficient of determination (R2 = 0.61) was discovered for the linear relationship between the infiltration rate as determined by the double ring infiltrometer and the soil penetration resistance (measured using a cone penetrometer down to a depth of 60 cm). Further, the nomographic representation of soil texture, final infiltration rate (mm h−1) and weighted mean of penetration resistance (kPa) was also developed. Furthermore, the regression analysis was done on five combinations (C-1, C-2, C-3, C-4 and C-5) of obtained parameters in which infiltration rate was taken as output and other parameters as input parameters to develop the pedotransfer model. Based on the obtained results, all combinations showed good correlation and C-3 with input parameters such as sand, silt, clay, porosity, GMC and AWC were found superior with good coefficient of determination values (R2 = 0.914). C-3 combination has the edge over C-4 combination (input: sand, silt, clay, porosity and organic carbon), having R2 values of 0.910. Therefore, the information obtained from the study will be helpful for policymakers in irrigation and other crop cultivation activities.

One-dimensional infiltration in a layered soil measured in the laboratory with the mini-disk infiltrometer

Abstract Layered soils can consist of a thin little permeable upper layer over a more permeable subsoil. There are not many experimental data on the influence of this upper layer on infiltration. The mini-disk infiltrometer set at a pressure head of –3 cm was used to compare infiltration of nearly 40 mm of water in homogeneous loam and clay soil columns with that in columns made by a thin layer (1 and 3 cm) of clay soil over the loam soil. For each run, the Horton infiltration model was fitted to the data and the soil sorptivity was also estimated by considering the complete infiltration run. For the two layered soils, the estimates of initial infiltration rate and decay constant were similar but a thicker upper layer induced 2.4 times smaller final infiltration rates. Depending on the infiltration parameter and the thickness of the upper layer, the layered soils were characterized by 2.2–6.3 times smaller values than the loam soil and 2.2–6.6 higher values than the clay soil. Sorptivity did not differ between the homogeneous clay soil and the layered soil with a thick upper layer and a thin layer was enough to induce a decrease of this hydrodynamic parameter by 2.5 times as compared with that of the homogeneous loam soil. Even a thin upper layer influences appreciably infiltration and hydrodynamic parameters. Layering effects vary with the thickness of the upper layer and the considered parameter. The applied experimental methodology could be used with other soils and soil combinations.

Quantifying the Effect of Soil Ameliorants on Soil Crusting by Means of Field Experiments in a Wildlife Protected Area, South Africa

Soil crusting (surface sealing) is widespread and serious in ecotouristic game parks and reserves in southern Africa, and especially South Africa. In this study, mineral soil crusts were found to be the problem in the Dinokeng Game Reserve (DGR), South Africa. Large areas of bare soil crusted areas were found in this reserve. The cause of this crusting was found to be historical agricultural practices such as cultivation with maize on non-arable soils and overgrazing by cattle. Negative impacts of soil crusting include reduction of water infiltration, leading to increased runoff and erosion and induced drought; inhibiting soil aeration; inhibiting germination and seedling emergence; and inhibiting root functioning and development. In this study in the DGR, a bare crusted area, where cultivation was abandoned 50 years before and there has been no recovery to rangeland since then, was selected for a field trial to determine the effectiveness of the application of various soil ameliorants on soil crust alleviation and improvement of water infiltration rate. The following ameliorants were evaluated: polyacrylamide (PAM) at levels of 5 and 20 kg/ha, gypsum at 2.5 t/ha, and molasses meal at 5 t/ha, as well as combinations of PAM and molasses meal, PAM and gypsum and gypsum and molasses meal. Brush packing, without any ameliorant applied, was also included as treatment, as well as a control with no treatments. PAM treatments increased final infiltration rate (FIR) by between 100–206%. The high efficacy of the lowest PAM treatment is at a cost of only USD 15 per hectare economically important. On the studied soil gypsum application reduced FIR by 81%, while molasses meal had minimal effect. These ameliorants can therefore not be recommended on such soil.

Hydrodynamic response of a loam soil after wetting with different methods

Different points in a field can be wetted with different natural or artificial rainfall amounts and intensities. Therefore, a non-uniform soil wetting could occur during short-term monitoring of soil hydrodynamic parameters and its global effect on soil characterization is not easily predictable. For an initially dry loam soil, a sequence of three beerkan infiltration runs was performed at fixed sampling points in a period of two weeks. Immediately after the first beerkan run, the soil was perturbed by adding an additional water volume differing with the sampling point by the amount of water (0, 100 or 227 mm) and the application methodology (rainfall simulation, another beerkan run). As compared with the initial conditions, the soil infiltration parameters (mean, initial and final infiltration rates; constant of the Horton’s infiltration model) decreased by 2.9–4.3 times after wetting. A decrease of these parameters by 1.6–2.3 times remained detectable at the end of the sampling period, even if the soil likely returned to wetness conditions close to the initial ones. Relative variability decreased too (coefficients of variation = 52–135%, depending on the parameter, for the initial runs and 36–95% for the final ones). Nevertheless, a link was recognized between the infiltration parameters determined in the subsequent runs of the sequence. The correlation was stronger when the initial runs were compared with the last runs (coefficients of determination, R2 = 0.104–0.749, depending on the parameter; R >0 at P = 0.05 in all cases) than with those performed immediately after the intermediate wetting (R2 varying from a non-significant value of 0.059 to significant 0.196–0.211 values). The hydrodynamic response of a disturbed soil appears overall related to that of the initially undisturbed soil even if the disturbing agent is not exactly the same over the sampled area. Performing other investigations by characterizing the antecedent soil conditions in more detail could help to improve interpretation and modelling of hydrological processes by a more realistic description of temporal variability of soil infiltration parameters.

Key soil properties influencing infiltration capacity after long-term straw incorporation in a wheat (Triticum aestivum L.)–maize (Zea mays L.) rotation system

Straw incorporation is increasingly being adopted in wheat (Triticum aestivum L.)–maize (Zea mays L.) rotation systems to improve soil physiochemical properties. To identify the main soil properties influencing infiltration capacity under long-term straw incorporation in a wheat–maize rotation system, the study set four treatments: no straw incorporation and fertilizer application, wheat straw incorporation with 276 kg nitrogen/ha, wheat and maize straw incorporation with 276 kg N/ha, and wheat and maize straw incorporation. The initial, average, and final infiltration rates were calculated to represent soil infiltration capacity. Compared with other treatments, wheat straw incorporation with 276 kg nitrogen/ha treatment significantly decreased soil bulk density, soil aggregate (DMWD) mean weight diameter measured using the dry sieving method, and weight rate of soil aggregates with diameters greater than 0.25 mm measured using the wet sieving method, and significantly increased total soil porosity, soil capillary porosity, field capacity, and weight rate of soil aggregates with diameters less than 0.25 mm measured using the wet sieving method. In contrast, wheat and maize straw incorporation treatment significantly increased soil bulk density and noncapillary porosity, but decreased total soil porosity, capillary porosity, and field capacity. The results of partial least squares regression indicated that the soil moisture content and DMWD were the primary factors influencing initial infiltration rate with positive regression coefficient. Higher total soil porosity, capillary porosity, field capacity, and DMWD contributed to higher final infiltration rate, while higher soil bulk density and noncapillary porosity were correlated with a lower final infiltration rate. The key influencing factors of average infiltration rate were soil bulk density, soil moisture content, total soil porosity, capillary porosity, and DMWD. The wheat straw incorporation with 276 kg nitrogen/ha treatment had higher infiltration rates than no straw incorporation and fertilizer application treatment. However, with an increase in straw amount, the influence of straw on infiltration showed a law of diminishing marginal returns. Therefore, wheat and maize straw incorporation with 276 kg nitrogen/ha treatments had a lower infiltration rate than wheat straw incorporation with 276 kg nitrogen/ha treatment. In addition, wheat and maize straw incorporation treatment had the lowest average and final infiltration rates of all treatments, indicating that excessive straw incorporation without nitrogen fertilizer had adverse effects on infiltration rates. This study furthers understanding of the influence of long-term straw incorporation on soil hydrological processes and helps rationally use straw resources in wheat–maize rotation systems.

Assessing the Effects of Plant Roots on Soil Water Infiltration Using Dyes and Hydrus-1D

Forestry eco-hydrology is closely related to root architecture, and soil water infiltration has been always associated with root architecture. In this study, dye infiltration experiments and HYDRUS-1D were used to quantify the effects of different root architectures on the dynamics of soil water infiltration, volumetric water content, and soil water pressure head. The results provide evidence that root channels acted as preferential flow paths for water infiltration and percolation into the soil. Maize fibrous roots, rubber trees fine roots, and Spartina alterniflora smooth roots easily penetrated the plough layer of an agriculture site, the hard soil layer of a forest site, and the alternating sandy and mud layers of an intertidal zone, respectively. The initial and final infiltration rates were significantly different between the rooted and rootless soil profiles. The root-induced infiltration events lowered the propagation time of the wetting front across the rooted soil profile by 33%–113% than the rootless soil (p < 0.05), and the volumetric water content of the saturation zone of the rooted soil profile increased by 12%–19% relative to the rootless soil (p < 0.05). Furthermore, the soil water pressure head increased from negative (i.e., unsaturated) to positive (i.e., saturated) in the saturated soil. This change was more pronounced in the maize fibrous roots soil profile, but less pronounced in the rubber fine roots’ soil profiles or the S. alterniflora smooth roots. The results indicate that the downward movement, volumetric water content, and soil water pressure head were higher in soil profiles having plant roots than the rootless soil, and the degree of roots effects depended on roots architectures, soil hardness, and soil layer configuration. The findings provide evidence that root channels can act as preferential flow paths for water infiltration and percolation into the soil.

Parameter Estimation and Assessment of Infiltration Models for Madjez Ressoul Catchment, Algeria

Evaluation and modeling of soil water infiltration are essential to all aspects of water resources management and the design of hydraulic structures. Nonetheless, research focused on experimental studies of infiltration rates in arid and semi-arid regions under unknown boundary conditions remains minimal. This paper investigates the characteristics of the spatial variability of infiltration over a semi-arid rural basin of Algeria. The experiments were conducted using a portable double-ring infiltrometer filled at an equal volume of approximately 100 L of water for each of the 25 catchment locations. Soil moisture contents at the proximity of each test location were evaluated in the laboratory as per the standard NF P94–050 protocol. The experimental results are used to produce the catchment infiltration curves using three statistically fitted infiltration models, namely Horton, Kostiakov, and Philip models. The reliability of the models was assessed using four performance criteria. The statistical regressions of the fitted models suggest that the Horton model is the most suitable to assess the infiltration rate over the catchment with mean coefficients of Nash = 0.963, CC = 0.985, RMSE = 1.839 (cm/h), and Bias = 0.241. The superiority of the Horton model suggests that the initial and final infiltration rates, primarily affected by soil type, initial soil moistures, and land cover, are important predictors of the modeling process over the Madjez Ressoul catchment. The results also infer that the applicability of other models to the different types of undeveloped soils in the study area requires advanced field investigations. This finding will support the understanding of the hydrologic processes over semi-arid basins, especially in advising crop irrigation schemes and methods and managing the recurring flood and drought over the country.

Estimating Infiltration in Open‐ended Furrow Irrigation by Modifying Final Infiltration Rate

AbstractThe Kostiakov–Lewis equation is one of the commonly used infiltration equations in furrow irrigation. Elliott and Walker developed a two‐point method to estimate coefficients of the Kostiakov–Lewis equation. The basic infiltration rate (fo) in the Kostiakov–Lewis equation is usually calculated by the inflow–outflow method to determine the other two Kostiakov–Lewis parameters. In that method the entire furrow is used as an infiltrometer, which can cause overestimation of fo. In this study, by considering a correction factor in the mathematical calculations where the newly calculated value of fo is represented as fo* and the values of the a and k parameters, as calculated during the advance phase, are represented as a* and k*. The amount of infiltration volume estimated by the proposed method was evaluated using 21 open‐ended furrow irrigation data sets by calculating the relative error (RE) index. The value of fo decreased and the values of a and k increased by using the proposed method as compared to the Elliott and Walker method. Therefore, the results showed that the proposed method estimated infiltration volume with greater accuracy (average absolute RE = 4.0%) as compared to the Elliott and Walker method (average absolute RE = 7.8%).

Prediction of infiltration rates of fallow and cultivated soils in Minna, Southern Guinea Savanna zone of Nigeria

Measurement and modelling of soil water infiltration under field condition are crucial to management of water resources, design and execution of drainage and irrigation projects for sustainable agricultural productivity and food security. This study was carried out to determine the time required to attain equilibrium or final infiltration rate of soils of Gidan-Kwano (a sandy loam) and Shintako (a loamy sand) sites around Minna, and reduce the tedium, time and cost associated with the measurement of soil infiltration rate. Three infiltration models (Kostiakov, Horton and Philip models) were evaluated. A double-ring infiltrometer was used to measure the infiltration rates of the soils at the two sites subjected to two land use management practices (fallow and cultivated soils) in Minna, Southern Guinea savanna zone of Nigeria. Infiltration runs were conducted at 0, 4, 8 and 12 weeks after cultivation. Results showed that the equilibrium infiltration rate of the tested soils was attained between 1 and 2 hours. The equilibrium infiltration rates of the fallow and cultivated soils were 21.54 and 7.62 cm hr-1, respectively, at the Gidankwano site, while the values at the Shintako site were 30.59 and 24.50 cm hr-1, respectively for the fallow and cultivated soils. Generally, the soils under fallow exhibited higher infiltration rates than cultivated ones. Curvefitting was done on Kostiakov’s, Horton’s and Philip’s infiltration models. Infiltration data generated using Kostiakov’s model were not significantly different from field-measured values at 5 % level of probability. The Kostiakov model was the most suitable for the prediction of infiltration rates of the soils investigated compared to Philip and Horton models. It is therefore, recommended for the soils tested, in the Southern Guinea savanna zone of Nigeria.

Influence of slope aspect and position on soil physical quality and management implications at University of Uyo Teaching and Research Farm, Akwa Ibom State, Nigeria


 
 
 The effect of north and south aspects (NA and SA) and positions viz upper (US), middle (MS) and lower (LS) on soil physical quality from 2000 to 2020 was evaluated at the University of Uyo Teaching & Research Farm, to identify management factors at the Farm. Results showed that coarse sand increased while clay content decreased significantly (p < 0.05) and soil textural class was loamy sand on slope aspects and positions. Soil bulk density and total porosity were similar on the slope aspects and positions. Saturated hydraulic conductivity was significantly (p < 0.05) higher on SA (10.6 cm h–1) than NA (3.1 cm h–1) but declined by 93.03% and 52.47%, respectively in 20 years. Soil organic carbon, water-stable aggregates, mean-weight diameter of soil aggregates and structural index decreased by 14.81% and 38.33%, 60.53% and 55.53%, 31.26% and 21.71%, and 48.60% and 69.0%, respectively in NA and SA within the 20-year period. One minute infiltration rate was similar on NA and SA, while final infiltration rate, cumulative infiltration, sorptivity and transmissivity were significantly (p < 0.05) different; these soil hydraulic properties decreased in NA and SA by 83.0% and 86.43%, 52.63% and 14.29%, 81.53% and 63.9%, 95.0% and 85.63% and 90.42% and 96.11%, respectively on the aspects after the 20 years. Slope aspects and positions were generally similar in their effects on soil physical quality attributes, most of which were degraded after the 20 years. Principal component analysis (PCA) identified seven soil quality management factors namely (1) water intake, (2) soil texture, (3) soil pore space, (4) and (6) Fe and Al oxide, and (5) and (7) soil structural stability factors that could be used to improve and conserve the soil and water for increases in crop production on the farm.
 
 

Parameterization of a comprehensive explicit model for single-ring infiltration

Comprehensive infiltration models can simultaneously describe transient and steady-state infiltration behaviors, and therefore can be applied to a range of experimental conditions. However, satisfactory model accuracy requires proper parameterization, including estimating the transition time from transient to steady-state flow conditions (τcrit). This study focused on improving the estimation of two parameters – τcrit and a second constant called a – used in a comprehensive, explicit, two-term model for single ring infiltration (hereafter referred to as the SA model). Different studies have recommended that a should be as low as 0.45 to as high as 0.91. Furthermore, τcrit is often obtained a-priori by assuming that steady-state conditions are reached before the end of an infiltration run. However, there has not been a systematic analysis of those terms for different soils and infiltration conditions. To investigate these open issues related to the use of the SA model, here we introduce a novel, iterative method for estimating τcrit and the parameter a. We then applied this method to both analytical and experimental infiltration data, and compared it with two existing empirical methods. The analytical infiltration experiments showed that τcrit was approximately 1.5 times larger than the maximum validity time of a similar two-term transient infiltration model. Further, the iterative method for obtaining τcrit had minimal effects on the a term, which varied between 0.706 and 0.904 and was larger for finer soils and when small water sources were used. Application of the proposed method was less efficient with experimental data. Only ~ 33% of the experiments yielding plausible estimates of a (i.e., a < 1), indicating that these infiltration model parameters often have high uncertainty. The successful runs indicated that a depended on the rate at which the initial infiltration rate approached the final infiltration rate. Depending on the fitting algorithm used, a had mean values of 0.74–0.78, which were intermediate between those suggested by previous studies. Altogether, these findings expand the applicability of the SA model by providing new methods for estimating τcrit and by showing that a does not need to be fixed a-priori. We expect that these advances will result in more reliable estimations of soil hydrodynamic parameters, including hydraulic conductivity.

Effect of Tillage for Rice Residue Management on Physical Properties of Soil

ABSTRACT The present study was conducted in wheat to study effect of four tillage practices viz mold board plowing to a depth of 25 cm followed by rotavator (PT25 + R), mold board plowing to a depth of 14 cm followed by rotavator (PT14 + R), zero tillage with happy seeder (ZT) and conventional practices of 2 discing + 2 cultivator followed by planking (CT) along with irrigation scheduling on soil physical properties for two consecutive years (2016–17 and 2017–18). Soil bulk density, mean weight diameter, water stable aggregates and organic carbon were significantly higher in ZT by 5.74%, 75.24%, 77.11% and 10.5% respectively compared to PT25 + R. Soil moisture retention was also significantly higher in ZT than all other tillage practices at 0.1 to 15 bar matic potential in 0–7.5, 7.5–15, 15–22.5 and 22.5–30 cm soil depths. Final infiltration rate was significantly higher in PT25 + R, PT14 + R and CT than ZT by 79%, 36% and 15% respectively. Cumulative infiltration was also significantly higher in PT25 + R, PT14 + R and CT than ZT by 71.7%, 33.0% and 15.6% respectively. Saturated hydraulic conductivity was significantly higher in PT25 + R than ZT by 72.5% and 81.7% in 0–7.5 and 7.5–15 cm layer respectively. Similarly unsaturated hydraulic conductivity was significantly higher in PT25 + R than ZT in both soil depths.

Numerical and artificial intelligence models for predicting the water advance in border irrigation

The water advance time (Ta) is needed for designing and evaluating surface irrigation systems. This study employed artificial neural networks (ANNs) and gene expression programming (GEP) techniques for estimating the water advance time in the border irrigation system as a function of inflow rate per unit width (Qb), length of water advance in the border (L), longitudinal slope (So), final infiltration rate of the soil (fo) and Manning roughness coefficient (n). The techniques were tested on field measurements from agricultural farms in three different provinces of Iran. Results showed that the ANN model was superior to the GEP model for the estimation of water advance time. The performance indicators for the ANN model were R2 = 0.966, RMSE = 7.805 min and MAE = 5.090 min, MBE = 0.312 and SI = 0.181. Results of the intelligence-based models were also compared with the WinSRFR model. Both ANN and GEP models predicted the water advance time more accurately than did the WinSRFR model.

Evaluation of some selected soil properties of a drip irrigated tomato field at different moisture regimes in South-Western Nigeria

Soil properties are important to the development of agricultural crops. This study determined some selected soil properties of a drip irrigated tomato (Lycopersicon esculentum M.) field at different moisture regime in South-Western Nigeria. The experiment was carried out using Randomized Complete Block Design with frequency and depth of irrigation application as the main plot and sub-plot, respectively in three replicates. Three frequencies (7, 5 and 3 days) and three depths equivalent to 100, 75 and 50% of water requirement were used. Undisturbed and disturbed soil samples were collected from 0-5, 5-10, 10-20 and 20-30 cm soil layers for the determination of some soil properties (soil texture, organic matter content, bulk density, infiltration rate and saturated hydraulic conductivity) were determined using standard formulae. Soil Water Content (SWC) monitoring was conducted every two days using a gravimetric technique. The soil texture was sandy loam for all the soil depths; average value of soil organic matter was highest (1.8%) in the 0-5 cm surface layer and decreased with soil depth; the soil bulk density value before and after irrigation experiment ranged from 1.48 and 1.73 g/cm3 and 1.5 and 1.76 g/cm3, respectively; there was a rapid reduction in the initial infiltration and final infiltration rate. Saturated hydraulic conductivity show similar trend although the 20-30 cm layer had the lowest value (50.84 mm/h); the SWC affect bulk density during the growing season. The study showed that soil properties especially bulk density and organic matter content affect irrigation water movement at different depth..

Water retention and irrigation characteristics of Vertisols in northwestern Turkey

The study comprised the analyses of 105 soil samples, located across the Thrace region of Turkey, collected from the horizons and sub-horizons of 16 soil pedons, classified as the Haploxerert and Calcixerert Great Groups of the Vertisol Order. Fundamental soil hydraulic and irrigation management properties, such as water retention and infiltration rate of the soils were evaluatedd along with the content and type of the dominating clay mineral. Results obtained for the major properties related to irrigation management such as the total total water holding capacity (TWHC), total available moisture (TAM) and the final infiltration rate of the studied soils, showed close dependence on the varying clay contents and clay types, and varied in the ranges of 393 and 635 mm/100 cm; 128 and 244 mm/100 cm; and 1.0–80.0 mm/h, respectively. In addition, it was determined, that values of the studied hydraulic characteristics are influenced also by the relative abundance and crystallinity degree of the dominant and accompanying clay mineral; availability of cracks, hard pans, self-mulching (pedoturbation) and gilgai formation. The diversity of the morphological, physical and/or chemical properties revealed that the studied soils required distinctive approaches and techniques in terms of irrigation management. The Türkgeldi Vertisol (Türkgeldi State Farm D11 and D12 locations) is an appropriate example for decreased pedoturbation and/or maturation in physical pedogenesis and in turn development of a stable soil structure, despite the high clay size particle and ssmectite contents throughout the profile.

Long-term conservation agriculture improves water properties and crop productivity in a Lixisol

Climate variability increasingly affects smallholder farmers in southern Africa. Conservation Agriculture (CA) practices have been proposed to improve the resilience of farming systems against the adversities of climate, specifically moisture stress. However, lack of detailed field data on soil water and chemical dynamics leads to over-reliance on simulation models without concrete evidence and ground-truthing of results. Here, we test the effects of different CA and conventional tillage (CP) practices on soil moisture content and water infiltration rate over a 14-year trial period. We also report soil chemical properties measured over 10 years from 0 to 30 cm soil depth. As study object, we used a CA long-term trial at the Monze Farmer Training Centre in Southern Zambia as it included different cropping systems and had parallel infiltration, soil moisture, soil chemical and crop yield measurements. Our results showed significant differences in average soil moisture in the first 60 cm among the cropping systems in different years with the basins plus mulching system having highest moisture content in most of the years. The interaction of cropping systems and years significantly affected water infiltration rate with highest final infiltration rates averaging 48.5 mm h−1 in the CA-based systems and the lowest in CP which averaged 12.6 mm h−1. Soil chemical properties did not significantly differ across the systems but across seasons and depths or their interaction. For crop yield, a direct seeded maize-cotton rotation (DS-MC) consistently had the highest grain yields across most of the years as compared to the CP practice. Maize grain yield significantly differed among the years with a strong influence from the rainfall. Regression analysis revealed significant effect of seasonal rainfall on both soil moisture content and crop yield. The DS-MC system showed high responses of grain yield to rainfall and moisture. This was caused by increased available water and a greater buffering capacity against water stress in the cotton rotation. Systems that conserve moisture, increase infiltration and yield are of paramount importance in environments of variable rainfall. CA-based systems may therefore have the potential to buffer the effects of climate variability and may provide greater resilience.

Effect of Land Use and Slope Position on Infiltration Characteristics on Sandstone-Derived Soils of Southern Nigeria

A study of some soil properties that influence infiltration under different land use types and slope positions in sandstone-derived soils was carried out in Akwa Ibom State, Southern Nigeria. Soil samples were collected in triplicate for laboratory analyses and infiltration tests were conducted using the double ring infiltrometer method. Analysis of variance, correlation and regression analyses were used to assess the data Oil Palm Plantation and Fallow Land increased the organic matter content of the soil, reduced bulk density, increased the soil porosity and aggregate stability over Continuously Cultivated Land. Downslope soil movement caused the upper slopes to lose their clay and organic matter to the middle and lower slope soils. Initial infiltration rate, final infiltration rate, cumulative infiltration, sorptivity and transmissivity varied highly across the studied locations but were not significantly (P ≤ 0.05) affected by land use, slope position and their interactions. Apparently higher infiltration rates were observed in all slope positions under Oil Palm Plantation and Fallow Land as a result of their apparently higher clay contents, total porosity, mean weight diameter, saturated hydraulic conductivity and organic matter contents over those of Continuously Cultivated Land. Heavier organic matter input will help to modify the upper slope soils for increased infiltration rates. Plantation agriculture should be adopted and continuous cultivation discouraged to increase water infiltration on sloppy terrains of the study area.

Determination of soil infiltration rate equation based on soil properties using multiple linear regression

Infiltration process plays important role in water balance concept particularly in runoff analysis, groundwater re-charged, and water conservation. Hence, increasing knowledge concerning infiltration process becomes essential for water manager to gain an effective solution to water resources problems. This study employed multiple linear regression for esti-mating infiltration rate where the soil properties used as the predictor variable and measured infiltration rate as the response variable. Field measurement was conducted at sixteen points to obtain infiltration rate using double ring infiltrometer and soil properties namely soil porosity, silt, clay, sand content, degree of saturation, and water content. The result showed that measured infiltration rate had an average initial infiltration rate (f0) of 6.92 mm∙min–1 and final infiltration rate (fc) of 1.49 mm∙min–1. Soil porosity and sand content showed a positive correlation with infiltration rate by 0.842, 0.639, respectively, while silt, clay, water content, and degree of saturation exhibited a negative correlation by –0.631, –0.743, –0.66 and –0.49, respectively. Three types of regression equations were established based on type of soil properties used as predictor varia-bles. The model performance analysis was conducted for each equation and the result shows that the equation with five predictor variables fMLR_3 = – 62.014 + 1.142 soil porosity – 0.205 clay, – 0.063 sand – 0.301, silt + 0.07 soil water content with R2 (0.87) and Nash–Sutcliffe (0.998) gave the best result for estimating infiltration rate. The study found that soil po-rosity contributes mostly to the regression equation that indicates great influence in controlling soil infiltration behavior.

Rain Transmission Losses Assessment in Arid Environment, Egypt: Numerical and Experimental Study

In water-scarce regions, Transmission Losses Assessment from rainfall is required for the Numerical and Experimental Study of groundwater recharge. This Study is an attempt to assess Transmission Losses and the infiltration rate at Wadi El-Assiuti, Egypt, field infiltration experiments were conducted to measure the infiltration and porosity at the target area, such as using a double-ring infiltrometer. Determination and Quantify the infiltration rate of the soil is very vital as input parameters of the hydrological modeling, irrigation planning and other natural or man-made Processes. Steady state infiltration rates have been determined in selected sites of Wadi El-Assiuti. Accurate determination of infiltration rates is fundamental for trustworthy prediction of surface runoff and groundwater recharge. Double ring infiltrometer was used to measure infiltration rate at selected sites. An important part of the study was the accurate and consistent measurement of infiltration rates‥ The infiltration rate was calculated according to the installation and operating instruction for the double ring in ASTM 2003. Final infiltration rates were 18 cm h−1, for the first observation site, 24.2 cm h−1for the second site and 59 cm h−1for the third site. The analysis indicated that the soil for the three selected areas is sandy soil. Infiltration rates were taken at 0 to70 minutes of 10 minutes intervals. The infiltration rate at the third site is high compared to the other two selected sites. After performing the experiments, soil samples have been gathered and analyzed in the laboratory for porosity analysis. The results of this study can therefore be applied in the prediction of saturated hydraulic conductivity of the surface layers and groundwater recharge, and in developing or selecting the most efficient irrigation methods. The results from this work have been also involved in a numerical hydrological model to estimate the Transmission Losses form rainfall at Wadi El-Assiuti using Hydro-BEAM.

Temporal variability of infiltration and roughness coefficients and furrow irrigation performance under different inflow rates

Accurate determination of temporal variability in infiltration parameters and Manning’s roughness coefficient is essential for appropriate design of surface irrigation systems to improve irrigation performance and reduce water losses. The objective of this study was to evaluate the effects of temporal variability and different inflow rates on infiltration parameters, Manning’s roughness, and irrigation performance. The field experiments included three inflow rates (1, 1.5 and 2 L/s) and three irrigation events (3rd, 5th and 8th events from 14. Sep. 2016 to 5 Nov. 2016) arranged in three replications at Salman Farsi Agro-Industry Sugarcane fields, located in the southwest of Iran. Also, experimental treatments were conducted in nine furrows with a length of 250 m, the width of 1.83 m and closed-end boundary. The results indicated that there was no significant difference in the Manning’s roughness during the growing season. On the other hand, there were significant reductions of the Manning’s roughness for inflow rates of 1.5 and 2 L/s in comparison with that obtained in inflow rate of 1 L/s. Results also indicated that the cut-off time and infiltrated volume were significantly affected by the temporal variability of infiltration parameters and roughness coefficient. The values of infiltration parameters during the growing season were variable because of various field conditions and sugarcane growth. There were significant differences between the values of parameters of the Kostiakov-Lewis infiltration equation during the growing season. The results showed that changing the inflow rate from 1 to 1.5 and 2 L/sec increased the value of final infiltration rate (f0) in the 5th irrigation event by 6.2% and 39.7% in the 8th irrigation event. The advance and recession times increased during the growing season, in which there was an effective difference in the 8th irrigation event compared to that in the 5th irrigation event. The temporal variability during growing season resulted in a significant reduction in application efficiency (from 74 to 49%), distribution uniformity (from 91 to 80%), and a significant increase in deep percolation (from 25 to 51%). The results showed that when the inflow rate increased from 1 to 1.5 and 2 L/s, the mean values of application efficiency decreased by 3.43 and 24.55%, deep percolation decreased by 27.34 and 34.17% and finally, distribution uniformity increased significantly by 9.7 and 9.3%, respectively.