Characterizing Hydrological Fluxes of Lesser Himalayan hillslopes

2020 ◽  
Author(s):  
Aliva Nanda ◽  
Sumit Sen
Keyword(s):  
Soil Moisture ◽  
Hydraulic Conductivity ◽  
Soil Temperature ◽  
Soil Properties ◽  
Negative Correlation ◽  
Soil Hydraulic Conductivity ◽  
Hydrological Fluxes ◽  
Soil Hydraulic ◽  
Hillslope Scale ◽  
Hillslope Processes

<p>Hillslope-scale studies play a vital role in understanding the spatial and temporal dynamics of hydrological fluxes of an ungauged watershed. The linkage between static (i.e. topography, soil properties and landuse) and dynamic (i.e. runoff, soil moisture and temperature) characteristics of a hillslope provides a new insight towards hillslope processes. Thus, two Lesser Himalayan hillslopes of Aglar watershed have been selected in two different landuses (grass-covered and agro-forested) and aspects (south and north). In this study, we analyzed the different hydrological fluxes i.e. rainfall, runoff, soil moisture and soil temperature along with the soil properties to get a holistic understanding of hillslope processes. We used the soil moisture dynamics and soil hydraulic conductivity as the major components to derive the hillslope hydrological connectivity. It was observed that the grassed (GA) hillslope generates less runoff than the agro-forested (AgF) hillslope as the upslope runoff of GA hillslope re-infiltrated in the middle portion due to higher soil hydraulic conductivity and surface resistance. Further, this explains that the runoff contributing areas are located at the lower and upper portions of hillslopes due to the presence of low soil hydraulic conductivity zones.  As both the hillslopes are dominated with Hortonian overland flow, the negative correlation was found between topographic indices (TWI) and soil moisture and positive correlation was noticed between soil hydraulic conductivity. Higher runoff (less infiltration) from AgF hillslope results in a higher negative correlation between TWI and soil moisture in comparison to GA hillslope. This results in a higher rate of change in soil temperature of GA hillslope than the AgF hillslope. After analyzing 40 rainfall events, it was concluded that a temperature drop of more than 2<sup>o</sup>C was recorded when the average rainfall intensity and event duration exceeds 7.5mm/hr and 7.5hr, respectively. The understanding of covariance of these hydrological fluxes will be used in the future to develop a hillslope-scale conceptual model.</p>

scholarly journals Large-scale lateral saturated soil hydraulic conductivity as metric for the connectivity of the subsurface flow paths at hillslope scale

2021 ◽  
Author(s):  
Mario Pirastru ◽  
Massimo Iovino ◽  
Hassan Awada ◽  
Roberto Marrosu ◽  
Simone Di Prima ◽  
...  
Keyword(s):  
Soil Moisture ◽  
Hydraulic Conductivity ◽  
Spatial Scale ◽  
Water Table ◽  
Subsurface Flow ◽  
Lateral Flow ◽  
Saturated Soil ◽  
Flow Paths ◽  
Soil Hydraulic Conductivity ◽  
Hillslope Scale

Lateral saturated soil hydraulic conductivity, Ks,l, is the soil property governing subsurface water transfer in hillslopes, and the key parameter in many numerical models simulating hydrological processes both at the hillslope and catchment scales. Likewise, the hydrological connectivity of lateral flow paths plays a significant role in determining the intensity of the subsurface flow at various spatial scales. The objective of the study is to investigate the relationship between Ks,l and hydraulic connectivity at the hillslope spatial scale. Ks,l was determined by the subsurface flow rates intercepted by drains, and by water table depths observed in a well network. Hydraulic connectivity of the lateral flow paths was evaluated by the synchronicity among piezometric peaks, and between the latter and the peaks of drained flow. Soil moisture and precipitation data were used to investigate the influence of the transient hydrological soil condition on connectivity and Ks,l. It was found that the higher was the synchronicity of the water table response between wells, the lower was the time lag between the peaks of water levels and those of the drained subsurface flow. Moreover, the most synchronic water table rises determined the highest drainage rates. The relationships between Ks,l and water table depths were highly non-linear, with a sharp increase of the values for water table levels close to the soil surface. Estimated Ks,l values for the full saturated soil were in the order of thousands of mm h-1, suggesting the activation of macropores in the root zone. The Ks,l values determined at the peak of the drainage events were correlated with the indicators of synchronicity. The sum of the antecedent soil moisture and of the precipitation was correlated with the indicators of connectivity and with Ks,l. We suggest that, for simulating realistic processes at the hillslope scale, the hydraulic connectivity could be implicitly considered in hydrological modelling through an evaluation of Ks,l at the same spatial scale.

scholarly journals Effects of Vineyard Inter-Row Management on Soils, Roots and Shallow Landslides Probability in the Apennines, Lombardy, Italy

Proceedings ◽  
2019 ◽  
Vol 30 (1) ◽  
pp. 41 ◽  
Author(s):  
Meisina ◽  
Bordoni ◽  
Vercesi ◽  
Maerker ◽  
Ganimede ◽  
...  
Keyword(s):  
Organic Matter ◽  
Hydraulic Conductivity ◽  
Soil Properties ◽  
Management Practices ◽  
Shallow Landslides ◽  
Root Density ◽  
Grass Cover ◽  
Root Reinforcement ◽  
Soil Hydraulic Conductivity ◽  
Soil Hydraulic

Cultivation of grapevines in sloping soils is very widespread all over the world, representing also a fundamental branch of the local economy of several hilly zones. Vineyards can be managed in different ways especially the inter-rows. These management practices may influence deeply soil properties and grapevine root development. Therefore, this work aims to analyze the effects of different agronomical practices of inter-rows on soil properties, grapevine root systems and proneness towards shallow landslides. We focused on traditional agricultural techniques of tillage and permanent grass cover as well as the alternation of these two practices between adjacent inter-rows. The studied parameters were: (i) soil physical and hydrological properties; (ii) soil biodiversity; (iii) root density; (iv) root mechanical properties and root reinforcement; (v) probability of occurrence of shallow landslides. The research was conducted in several test-sites of the Oltrepò Pavese (Lombardy region, north-western Italy), one of the most important Italian zones for wine production in northern Italian Apennines. Among the examined soil properties, soil hydraulic conductivity was the most influenced one by different soil management practices. The absence of soil tillage allowed to increase superficial (first 0.2 m of soil) hydraulic conductivity, as a consequence of higher macroporosity and amount in organic matter. Within the soil biological features, soil microarthropod communities showed more complexity where permanent grass cover or alternation management of the inter-rows were applied. Regarding the features of the grapevine root system, vineyards with alternation management of inter-rows had the highest root density and the strongest root reinforcement, of up to 45% in comparison to permanent grass cover, and up to 67–73% in comparison to tilled vineyards. As a consequence, slopes with medium steepness (10–18°) were unstable if inter-rows of vineyards were tilled, while vineyards with permanent grass cover or alternation in the inter rows promoted the stability of slopes with higher steepness (> 21–25° for vineyards with permanent grass cover in the inter rows, 28–33° for vineyards with alternation). The results of this study yielded important information to establish effective management practices of vineyards such as conserving organic matter and reducing slope instabilities by a better development of the root apparatus. Possible land use managements acting as mitigation measures for shallow landslides susceptibility could be also implemented. This work was supported by the project Oltrepò BioDiverso, funded by Fondazione Cariplo in the frame of AttivAree Program.

Simplified estimation of unsaturated soil hydraulic conductivity using bulk electrical conductivity and particle size distribution

Soil Research ◽  
2013 ◽  
Vol 51 (1) ◽  
pp. 23 ◽  
Author(s):  
Mohammad Reza Neyshabouri ◽  
Mehdi Rahmati ◽  
Claude Doussan ◽  
Boshra Behroozinezhad
Keyword(s):  
Electrical Conductivity ◽  
Particle Size ◽  
Hydraulic Conductivity ◽  
Particle Size Distribution ◽  
Size Distribution ◽  
Unsaturated Soil ◽  
Soil Core ◽  
Soil Hydraulic Conductivity ◽  
Core Samples ◽  
Soil Hydraulic

Unsaturated soil hydraulic conductivity K is a fundamental transfer property of soil but its measurement is costly, difficult, and time-consuming due to its large variations with water content (θ) or matric potential (h). Recently, C. Doussan and S. Ruy proposed a method/model using measurements of the electrical conductivity of soil core samples to predict K(h). This method requires the measurement or the setting of a range of matric potentials h in the core samples—a possible lengthy process requiring specialised devices. To avoid h estimation, we propose to simplify that method by introducing the particle-size distribution (PSD) of the soil as a proxy for soil pore diameters and matric potentials, with the Arya and Paris (AP) model. Tests of this simplified model (SM) with laboratory data on a broad range of soils and using the AP model with available, previously defined parameters showed that the accuracy was lower for the SM than for the original model (DR) in predicting K (RMSE of logK = 1.10 for SM v. 0.30 for DR; K in m s–1). However, accuracy was increased for SM when considering coarse- and medium-textured soils only (RMSE of logK = 0.61 for SM v. 0.26 for DR). Further tests with 51 soils from the UNSODA database and our own measurements, with estimated electrical properties, confirmed good agreement of the SM for coarse–medium-textured soils (<35–40% clay). For these textures, the SM also performed well compared with the van Genuchten–Mualem model. Error analysis of SM results and fitting of the AP parameter showed that most of the error for fine-textured soils came from poorer adequacy of the AP model’s previously defined parameters for defining the water retention curve, whereas this was much less so for coarse-textured soils. The SM, using readily accessible soil data, could be a relatively straightforward way to estimate, in situ or in the laboratory, K(h) for coarse–medium-textured soils. This requires, however, a prior check of the predictive efficacy of the AP model for the specific soil investigated, in particular for fine-textured/structured soils and when using previously defined AP parameters.

Simple Field Methods for Estimating Soil Hydraulic Conductivity

1980 ◽  
Vol 44 (1) ◽  
pp. 3-7 ◽  
Author(s):  
P. L. Libardi ◽  
K. Reichardt ◽  
D. R. Nielsen ◽  
J. W. Biggar
Keyword(s):  
Hydraulic Conductivity ◽  
Field Methods ◽  
Soil Hydraulic Conductivity ◽  
Soil Hydraulic

Changes in soil hydraulic conductivity after prescribed fires in Mediterranean pine forests

2019 ◽  
Vol 232 ◽  
pp. 1021-1027 ◽  
Author(s):  
P.A. Plaza-Álvarez ◽  
M.E. Lucas-Borja ◽  
J. Sagra ◽  
D.A. Zema ◽  
J. González-Romero ◽  
...  
Keyword(s):  
Hydraulic Conductivity ◽  
Pine Forests ◽  
Prescribed Fires ◽  
Soil Hydraulic Conductivity ◽  
Soil Hydraulic ◽  
Mediterranean Pine
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