Browsing by Author "El Gharous, Mohamed"

Now showing 1 - 3 of 3
  • Thumbnail Image
    ItemOpen Access
    Changes in soil surface properties under simulated rainfall and the effect of surface roughness on runoff, infiltration and soil loss
    (Elsevier, 2023-02-03) Bahddou, Sophia; Otten, Wilfred; Whalley, W. Richard; Shin, Ho-Chul; El Gharous, Mohamed; Rickson, R. Jane
    Soil erosion by water is a result of detachment of particles or small aggregates from the soil surface followed by transport of the detached material. One of the elements that affects surface runoff and soil erosion is the soil surface roughness (SSR). Prior research reports that increasing SSR reduces generation of runoff and soil loss. In addition to that, it is widely reported that across-slope oriented roughness is better at controlling soil and water losses. However, to date there have been few studies into the effect of both magnitude and orientation of SSR on runoff, infiltration and soil erosion at the sub process level (i.e. by raindrop splash and overland flow), occurring simultaneously. In this study, the effects of up-down-slope oriented SSR (Treatment A), across-slope oriented SSR (Treatment B) and random SSR (Treatment C) were compared, along with a smooth surface (Treatment D). A moderate slope gradient of 10 %, a simulated rainfall intensity of 90 mm hr−1 and storm durations of 15 or 30 min were considered. The SSR was measured using the chain method, before and after the rainfall event. Images of the soil surface were taken using a hand-held laser scanner to monitor the effect of rainfall on the surface morphology. The outcome of this study shows that rainfall erosivity increases the SSR of the initially smooth surface, but decreases that of the initially rough surface, particularly in the random SSR treatment, where the decrease in SSR was 64 % of the pre-rainfall condition. This was due to the effects of raindrop impacts and overland flow. The random SSR treatment generated significantly more runoff and soil loss, and less infiltration than all other treatments (p < 0.001), but for raindrop splash erosion, there was no significant difference between random SSR and the other treatments. Contrary to expectations, the across-slope oriented SSR did not always reduce runoff and soil erosion compared to the up-down-slope orientation. This can be explained by degradation of surface microtopography by rainfall and runoff, as confirmed by the post-rainfall SSR measurements.
  • No Thumbnail Available
    ItemOpen Access
    Effect of surface roughness on runoff, infiltration and soil loss
    (Cranfield University, 2023-02-06 12:12) Bahddou, Sophia; Otten, Wilfred; Rickson, Jane; Whalley, Richard; Shin, Ho-Chul; El Gharous, Mohamed
    The excel spreadsheet presents the raw data generated from the experiments quantifying soil erosion that are described in the paper by Bahddou et al., 2023, published in Geoderma (Bahddou et al., 2023. Changes in soil surface properties under simulated rainfall and the effect of surface roughness on runoff, infiltration and soil loss). The experimental design and the statistical method are mentioned in the methodology section of the paper. The soil surface roughness data is expressed in two columns (E-F) presenting the measurements before and after the rainfall event (Table 3 and Figure 4 of the paper by Bahddou et al). The variables of the runoff, infiltrate, soil loss and sediment concentration are expressed in the columns G-R, where each variable is expressed in three columns presenting the 1st fifteen minutes of the rainfall event, the 2nd fifteen minutes of the rainfall event and the total 30 minutes of the rainfall event (Table 4 and Figures 6 and 7 in the paper by Bahddou et al., 2023). The columns S-U present the splash erosion after 30 minutes of rainfall, including the measurements on the ridges and in the furrows of Treatment B. More details are in the Materials and Methods section and the Results sections of the publication.
  • Thumbnail Image
    ItemOpen Access
    Evaluation of pedotransfer functions to estimate some of soil hydraulic characteristics in North Africa: a case study from Morocco
    (Frontiers, 2023-02-08) Beniaich, Adnane; Otten, Wilfred; Shin, Ho-Chul; Cooper, Hannah; Rickson, R. Jane; Soulaimani, Azia; El Gharous, Mohamed
    Soil hydraulic properties are an important factor to optimize and adapt water management for a given crop. Pedotransfer functions (PTFs) present a solution to predict soil variables such as hydraulic properties, using fundamental soil properties. In this research, we compared two sources of soil information: iSDAsoil data and field data, in four regions in Morocco. We then used this data to evaluate published data and developed new PTFs using soil information to estimate soil gravimetric moisture content at saturation (w0), field capacity (w330) and permanent wilting point (w15000). A total of 331 samples were collected from four regions: Doukkala, Gharb-Loukous, Moulouya and Tadla. The data was divided into calibration and validation datasets. For development of different PTFs, we used simple linear regression, multiple linear regression, regression tree, Cubist algorithm, and random forest approaches. PTFs developed by Dijkerman (Geoderma, 1988, 42, 29–49) presented the best performance, showing lower RMSE, Bias and MAE compared to other PTFs. Using multiple linear regression to develop PTFs, models based on clay, silt and soil organic matter as input variables showed the best performance after calibration (R2 of 0.590, 0.785, 0.786 for w0, w330, and w15000, respectively). Regarding the techniques based on machine learning, random forest showed the best performance after calibration compared with other algorithms (R2 of 0.930, 0.955, 0.954 for w0, w330, and w15000, respectively). PTFs represent a low cost and easy technique to estimate soil hydraulic properties, to improve water management efficiency for the farmers.