Soil Moisture Retention Characteristics Of Saprock From The Weathering Profile Over A Biotite-Muscovite Granite In Peninsular Malaysia

The weathering profile at the slope cut near Km 16 of the Kuala Lumpur - Ipoh trunk road can be differentiated into an upper, 11.8 m thick pedological soil (zone I) and a lower, 31.9 m thick saprock (zone II) comprising silty sandy gravels that distinctly preserve the minerals, textures and structures of the original granite. In order to investigate the influence of particle size distributions on soil moisture retention characteristics, saprock samples were collected at depths of 26.53 m (Sample A), 31.29 m (Sample B) and 41.93 m (Sample C). Samples A and B, with porosities of 37%, comprise 33% gravel, 27% sand, 22% silt and 18% clay, and 31% gravel, 24% sand, 25% silt and 22% clay, respectively. Sample C with a porosity of 44% consists of 24% gravel, 28% sand, 38% silt and 10% clay. Tests with the pressure plate method show increasing suctions from 0 kPa through 0.98 kPa and 9.8 kPa to 33 kPa and 1,500 kPa to result in gravimetric soil moisture retentions of 31.9% through 28.6% and 23.3% to 16.9% and 6.8% in sample A, of 32.1% through 24.9% and 21.5% to 17.8% and 7.4% in sample B, and of 31.5% through 30.3% and 27.30% to 23.5% and 9.5% in sample C. Regression analyses of gravel, sand and clay contents plotted against moisture contents retained at high suctions (33 kPa and 1,500 kPa) yield negative trends with variable correlation coefficients (R2), though plots involving silt contents yield positive trends with large correlation coefficients (R2 >0.9966). It is concluded that adsorption of water on surfaces of silt sized particles (of mainly sericite derived from weathering of feldspars) that gives rise to the retention of soil moisture in saprock.

The Application of Hydrogel in Agriculture for Reducing High Pumping of Irrigation Water in Algeria

The application of hydrogel in agriculture has gained a wide interest in the last decades due to the great benefits that it has provided to this sector. In Algeria, agriculture suffers from two main issues: water shortage and climate change, especially in the south of the country (Sahara), which is classified within the arid and semi-arid regions, where irrigation is based exclusively on groundwater. This paper presents an experiment of hydrogel application in agricultural soil for reducing overexploitation of groundwater used for irrigation. Hydrogels are super absorbent polymers. They are biodegradable and have the ability to absorb and retain a large amount of water. The aim of this work is to evaluate the effect of hydrogel on the efficiency of soil moisture retention through treating sandy soil with different doses of hydrogel. The results indicate that the application of hydrogel can increase the water retaining capacity of sandy soil up to 40%.

Modeling groundwater table and runoff in self-organizing hydrologically sensitive areas

<p>Understanding the hydrology of hydrologically sensitive areas (or runoff source areas) is crucial for evaluating and predicting runoff and the environmental fate of applied chemicals. However, while modeling these areas, one must deal with an overwhelmingly complex, coupled nonlinear system with feedbacks that operate at multiple spatiotemporal scales. Sufficient detailed information on the physical environment that these models represent is often not available. Consequently, the simulation's results, even after extensive calibration, are often disappointing. Fortunately, self-organization of hydrological systems' makes it possible to simplify watershed models and consider the landscape functions instead of small-scale physics. These simplified (or surrogate) models provide the same or better objective results than their complex counterparts, are much less data-intensive, and can be used for engineering applications and planning purposes.</p><p>This study aims to experimentally expose the landscape hydrological self-organization of a periodically saturated variable source area with a shallow perched water table and a humid climate. The study site is a four-hectare runoff source area near Cornell University, Ithaca, NY, US. The saturated hydraulic conductivity is greater than the rainfall intensity. The area has a single outlet through a notched weir, and the only inflow is from precipitation. We analyzed observed water table heights and field outflow and found the theory behind the self-organization of runoff processes specific to that landscape type. We determined a priori the thresholds for runoff in a surrogate model using the soil moisture retention curve. </p><p>Weir measurements showed that outflow on the day following rainfall had decreased by orders of magnitude, indicating the soil water had returned to static equilibrium. Under the equilibrated state, established theory indicates that the matric potential decreases linearly with depth above the shallow groundwater. The matric potential (and thus the retention curve) determined the soil water distribution. Another property from the whole field perspective is that excess rainfall above saturation becomes runoff.</p><p>The reason for self-organization of the source area was that the soil moisture retention curve (which is similar for the whole source area) determined daily both the soil moisture content and the water table change using rainfall and evaporation as drivers. Since the source area behaved similarly, a simple surrogate water balance could predict the aggregated area's hydrological behavior. The nonlinear and small-scale physics associated with the field's complexity determined the rate that equilibrium is reached, which is always less than one day due to high macropore conductivity, greatly simplifying surrogate models that make daily predictions.</p>

Can soils act as environmental sponges to help reduce flooding?

<p>Flooding presents a serious socioeconomic challenge to riverine communities across the world, impacting >300 million people each year and causing loss of life, damage to infrastructure, long-term mental and physical health problems, and threatening food security. Across many parts of the globe, including north-west Europe, climate change is projected to increase the magnitude, frequency, and intensity of rainfall events, thus exacerbating future flood risk and increasing the demand for flood alleviation schemes. Historically, flood prevention strategies have focused on constructing hard defences that restrict the overbank flows and aim to convey them downstream. However, as floods become larger and more difficult to predict, the construction of ever-higher defences becomes unfeasible. As such, natural-based solutions are being adopted as a more cost-effective and sustainable approach to managing flood waters through upland attenuation in leaky dams and offline storage in reservoirs in the lowlands. Here we demonstrate the feasibility and efficacy of using agricultural soils as “environmental sponges” to retain moisture and reduce downstream flood peaks in a heavily-managed lowland catchment. We use combined field, laboratory, and modelling approach to quantify how increases in soil organic matter – introduced through cover crops – can increase soil moisture retention at the field scale and perform groundwater and catchment modelling scenarios to assess how these changes can be extrapolated up to the catchment scale and used to forecast changes in downstream flood risk across a suite of future hydro-climatic and soil management scenarios.</p>

Soil moisture retention on slopes under different agricultural land uses in hilly regions of Southern Transdanubia

Increasingly severe weather extremes are predicted as one of the consequences of climate change. According to climatic models, weather extremities induce higher risks for both flood and drought in the Carpathian Basin. Throughout the 19th and 20th centuries, flood control relied on cost-intensive engineering structures, but recently ecological solutions have come to the fore. Flood hazard on major rivers could be mitigated if multiple and cumulative water retention opportunities are exploited on the upper sections of tributary catchments. Appropriate land use and landscape pattern changes can shift the infiltration to run-off ratio to the benefit of the former. In the Transdanubian Hills of Southwest Hungary three study areas with different agricultural land use types had been selected and investigated for the impact of landscape micro-features on soil moisture retention capacity with the purpose of conserving water from wet periods for the times of drought. Marked differences in moisture dynamics have been detected between arable land, grasslands and orchards. This fact underlines the need for integrated soil and water conservation. Drought risk was found to be the highest on ploughland. Favourable soil water budgets have been observed in the fields as a function of land use: less intensive types, like grazing land and orchards (particularly tree rows), were identified as places of high water retention capacity. Although serious water stress conditions were also reached in the orchard, it markedly mitigated drought conditions compared to the ploughland.

THE SOIL MOISTURE RETENTION PATTERN OF SOME SELECTED OF ORGANIC MEDIA UNDER A GREENHOUSE STRUCTURE

This research aimed to investigate the soil moisture retention of some selected organic media for growing cucumber plant. The experiment was conducted in a greenhouse structure and moisture content of each of the organic media was determined by a calibrated moisture meter, which was taken before and after the irrigation. The water application was uniform, using a drip irrigation kit for potted system with a capacity of 75cl storage each for the treatments. The pH values of each of the organic media used shows moderate alkalinity. The mean and sample variance of the moisture retention pattern for each of the media gave; saw dust (3.61, 0.073), maize husk (3.41, 0.044), rice husk (3.92, 0.034), eucalyptus leaves (3.27, 0.021), sawdust + soil (2.76, 0.0416), maize husk + soil (2.94, 0.153), rice husk + soil (3.88, 0.069), eucalyptus leaves + soil (2.76, 0.041), eucalyptus leaves + soil unsterilized (3.77, 0.074), and sandy loamy (23.345, 0.009). Moisture retention pattern of the selected media show high moisture retention in sandy loam while other media show a low moisture retention in approximately ratio 6:1, the sample variance shows small variance indicating how the data point spread out. It can be assumed that low retention could be as a result of the presence of fibre or coarse particles given room for large pore spaces that allows easy moisture drain from the organic media. It can also be deduced from the results that maize husk is least suitable for growing purposes because of unsteady moisture retention pattern.