scholarly journals Observing soil moisture temporal variability under fluctuating climatic conditions

2008 ◽  
Vol 5 (2) ◽  
pp. 935-969 ◽  
Author(s):  
A. Longobardi
Keyword(s):  
Soil Moisture ◽  
Climatic Conditions ◽  
Annual Rainfall ◽  
Dry Period ◽  
Experimental Site ◽  
Rainfall Variation ◽  
Dry Soil ◽  
Moisture Conditions ◽  
Increasing Precipitation

Abstract. The paper focuses on the observation of interannual and intra-annual climate variability impact on soil moisture temporal patterns and variation, for an experimental site located in Southern Italy and characterized by a typical Mediterranean climate. Analysed data consist of three years soil water content time series measured during the period 2004–2007, under intermediate (2004/2005), wet (2005/2006) and dry (2006/2007) climatological conditions. Results show that, for the case study, interannual precipitation fluctuation highly impact the annual soil moisture cycle, modifying the number and length of characteristic periods revealed by the cycle patterns. Annual rainfall variation also affects the weight of the wet and dry soil moisture conditions, making the distinction between preferred states more and more evident for increasing precipitation variability. Intra-annual precipitation fluctuation instead mainly impact soil moisture dynamic during the dry period of the year, shifting the position of the modes and the weight of the wet mode and nearly leading the dry mode to disappear for larger mean seasonal rainfall. Reported analyses would be a support and a premise for further modeling implications.

scholarly journals Germination of Ocotea pulchella (Nees) Mez (Lauraceae) seeds in laboratory and natural restinga environment conditions

2009 ◽  
Vol 69 (3) ◽  
pp. 935-942 ◽  
Author(s):  
LA. Pires ◽  
VJM. Cardoso ◽  
CA. Joly ◽  
RR. Rodrigues
Keyword(s):  
Soil Moisture ◽  
Soil Moisture Content ◽  
Weibull Model ◽  
Limiting Factors ◽  
Base Temperature ◽  
Temperature Range ◽  
Optimal Temperature Range ◽  
Dry Soil ◽  
Moisture Conditions ◽  
Temperature Water

The germination response of Ocotea pulchella (Nees) Mez seeds to light, temperature, water level and pulp presence is introduced. The laboratory assays were carried out in germination chambers and thermal-gradient apparatus, whereas the field assays were performed in environments with distinct light, temperature and soil moisture conditions within a permanent parcel of Restinga forest of the Parque Estadual da Ilha do Cardoso, Cananéia, São Paulo. The seeds do not exhibit dormancy, they are non photoblastic, and a loss of viability in dry stored seeds can be related to a decrease in water content of the seed. The presence of the pulp and the flooded substratum influenced negatively the germination of O. pulchella seeds tested in the laboratory. Otherwise, light and temperature probably are not limiting factors of the germination of O. pulchella seeds in the natural environment of Restinga. The optimum temperature range for germination of Ocotea pulchella seeds was 20 to 32 ºC, the minimum or base temperature estimated was 11 ºC and the maximum ranged between 33 and 42 ºC. The isotherms exhibited a sigmoidal pattern well described by the Weibull model in the sub-optimal temperature range. The germinability of O. pulchella seeds in the understorey, both in wet and dry soil, was higher than in gaps. Germination was not affected by fluctuations in soil moisture content in the understorey environment, whereas in gaps, germination was higher in wet soils. Thus, the germination of this species involves the interaction of two or more factors and it cannot be explained by a single factor.

Multidimensional context for extreme analysis of daily streamflow, rainfall and accumulated rainfall across USA

2020 ◽  
Author(s):  
Maria Nezi ◽  
Ioannis Tsoukalas ◽  
Charalampos Ntigkakis ◽  
Andreas Efstratiadis
Keyword(s):  
Soil Moisture ◽  
Daily Rainfall ◽  
Extreme Rainfall ◽  
Annual Rainfall ◽  
Event Analysis ◽  
Antecedent Soil Moisture ◽  
Daily Streamflow ◽  
Accumulated Rainfall ◽  
Moisture Conditions ◽  
Parameter Values

<p>Statistical analysis of rainfall and runoff extremes plays a crucial role in hydrological design and flood risk management. Usually this analysis is performed separately for the two processes of interest, thus ignoring their dependencies, which appear at multiple temporal scales. Actually, the generation of a flood strongly depends on soil moisture conditions, which in turn depends on past rainfall. Using daily rainfall and runoff data from about 400 catchments in USA, retrieved from the MOPEX repository, we investigate the statistical behavior of the corresponding annual rainfall and streamflow maxima, also accounting for the influence of antecedent soil moisture conditions. The latter are quantified by means of accumulated daily rainfall at various aggregation scales (i.e., from 5 up to 30 days) before each extreme rainfall and streamflow event. Analysis of maxima is employed by fitting the Generalized Extreme Value (GEV) distribution, using the L-moments method for extracting the associated parameters (shape, scale, location). Significant attention is paid for ensuring statistically consistent estimations of the shape parameter, which is empirically adjusted in order to minimize the influence of sample uncertainty. Finally, we seek for the possible correlations among the derived parameter values and hydroclimatic characteristics of the studied basins, and also depict their spatial distribution across USA.</p>

Climatic conditions for seedling recruitment within perennial grass swards in south-eastern Australia

2012 ◽  
Vol 63 (4) ◽  
pp. 389 ◽  
Author(s):  
R. Thapa ◽  
D. R. Kemp ◽  
M. L. Mitchell
Keyword(s):  
Soil Moisture ◽  
New South ◽  
Perennial Grass ◽  
New South Wales ◽  
Climatic Conditions ◽  
South Eastern ◽  
South Wales ◽  
Eastern Australia ◽  
Moisture Conditions ◽  
South Eastern Australia

Recruitment of new perennial grass plants within existing grassland ecosystems is determined by seed availability, suitable microsites, nutrients and climatic conditions, water and temperatures. This paper reports on the development of criteria to predict recruitment events using modelled soil moisture conditions associated with recruitment of species in five field experiments at Orange (Phalaris aquatica), Trunkey Creek (Austrodanthonia spp.), and Wellington (Bothriochloa macra) in central New South Wales, Australia, and the frequency of those conditions during the past 30 years. Recruitment events were recorded when a rainfall event (median 68 mm across the three sites) kept the surface volumetric soil moisture (0–50 mm) above the permanent wilting point for at least 15 continuous days, allowing for, at most, two ‘dry days’ in between. A key finding from our study is that rainfall events creating favourable soil moisture conditions for seedling emergence typically occurred in the second half of February, sometimes extending to early March. Previously it was thought that recruitment would more likely occur through autumn, winter, and spring when rainfall in southern Australia is more reliable. The 30 years’ data (1975–2004) showed that the P. aquatica site had a median of 20 continuous moist days each year in February–March, whereas, there were 16 and 10 days for the Austrodanthonia and B. macra sites, respectively. The probabilities of exceeding seven or 15 continuous days of moist surface soil were 98% and 78% at the P. aquatica site, 91% and 49% at the Austrodanthonia site, and 73% and 30% at the B. macra site, and indicated that some recruitment is possible in most years. These analyses were extended to several sites across New South Wales, Victoria, and Tasmania to estimate the frequency with which recruitment could occur within natural swards. Across these sites, the probabilities of exceeding seven continuous days of soil moisture were >55% and of exceeding 15 continuous days were lower, which showed that suitable climatic conditions exist during late summer–early autumn across south-eastern Australia for a recruitment event to occur. Future research may show that the criteria developed in this paper could have wider regional application.

scholarly journals Interplays between State and Flux Hydrological Variables across Vadose Zones: A Numerical Investigation

Water ◽  
2019 ◽  
Vol 11 (6) ◽  
pp. 1295 ◽  
Author(s):  
Wang ◽  
Wang ◽  
Zhang
Keyword(s):  
Soil Moisture ◽  
Vadose Zone ◽  
Hydraulic Properties ◽  
Climatic Conditions ◽  
Zone Model ◽  
Residual Soil ◽  
Soil Hydraulic Properties ◽  
Soil Hydraulic ◽  
Moisture Conditions ◽  
Hydrological Variables

Knowledge of both state (e.g., soil moisture) and flux (e.g., actual evapotranspiration (ETa) and groundwater recharge (GR)) hydrological variables across vadose zones is critical for understanding ecohydrological and land-surface processes. In this study, a one-dimensional process-based vadose zone model with generated soil hydraulic parameters was utilized to simulate soil moisture, ETa, and GR. Daily hydrometeorological data were obtained from different climate zones to drive the vadose zone model. On the basis of the field phenomenon of soil moisture temporal stability, reasonable soil moisture spatiotemporal structures were reproduced from the model. The modeling results further showed that the dependence of ETa and GR on soil hydraulic properties varied considerably with climatic conditions. In particular, the controls of soil hydraulic properties on ETa and GR greatly weakened at the site with an arid climate. In contrast, the distribution of mean relative difference (MRD) of soil moisture was still significantly correlated with soil hydraulic properties (most notably residual soil moisture content) under arid climatic conditions. As such, the correlations of MRD with ETa and GR differed across different climate regimes. In addition, the simulation results revealed that samples with average moisture conditions did not necessarily produce average values of ETa and GR (and vice versa), especially under wet climatic conditions. The loose connection between average state and flux hydrological variables across vadose zones is partly because of the high non-linearity of subsurface processes, which leads to the complex interactions of soil moisture, ETa, and GR with soil hydraulic properties. This study underscores the importance of using soil moisture information from multiple sites for inferring areal average values of ETa and GR, even with the knowledge of representative sites that can be used to monitor areal average moisture conditions.

scholarly journals Volume Changes in Undisturbed Clay Profiles in Western Canada

1963 ◽  
Vol 1 (1) ◽  
pp. 27-42 ◽  
Author(s):  
J J Hamilton
Keyword(s):  
Soil Moisture ◽  
Unsaturated Soils ◽  
Free Water ◽  
Thermal Conditions ◽  
Climatic Conditions ◽  
Western Canada ◽  
Undisturbed Soil ◽  
Temperature And Precipitation ◽  
Frost Penetration ◽  
Moisture Conditions

As part of an over-all study of the performance of building foundations in highly plastic soil areas of western Canada, the Division of Building Research has been measuring ground movements and changes in soil moisture conditions in grass-covered, undisturbed soil profiles under climatic conditions ranging from sub-humid to semi-arid. Results of measurements begun in 1951 in Winnipeg, Manitoba, and more recently those in Regina, Eston, and Tisdale, Saskatchewan, are reported. Results of a theoretical soil moisture depletion calculation, based on Thornthwaite's potential evapo-transpiration concept, are presented. It is proposed as a more rational way of measuring the vegetation-climate factor in humid to sub-humid climates than simply comparing air temperature and precipitation with long-term averages. Empirical relationships are suggested between calculated soil moisture depletion, the depth of free water table, and the depth of frost penetration under similar thermal conditions but different soil moisture conditions. Shrinkage in situ of undisturbed, unsaturated soils at temperatures well below 32° F has been observed and is attributed to thermal air-void volume change.

Factors Affecting Performance of Preemergence Herbicides

Weed Science ◽  
1968 ◽  
Vol 16 (4) ◽  
pp. 457-462 ◽  
Author(s):  
L. S. Jordan ◽  
J. M. Lyons ◽  
W. H. Isom ◽  
B. E. Day
Keyword(s):  
Soil Moisture ◽  
Weed Control ◽  
Climatic Conditions ◽  
Echinochloa Crusgalli ◽  
Factors Affecting ◽  
Dry Soil ◽  
Preemergence Herbicides ◽  
Factors Affecting Performance

Spray and granular forms of isopropyl N-(3-chlorophenyl)-carbamate (CIPC, ethyl N,N-dipropylthiocarbamate (EPTC), a,a,a-trifluoro-2,6-dinitro-N,N-dipropyl-p-toluidine (trifluralin) and 2,4-bis(isopropylamino) -6-methylmercapto-s-triazine (prometryne) were incorporated preemergence to barnyardgrass Echinochloa crusgalli (1.) Beauv.) and broadleaf weeds with a rotary tiller, wheel hoe, rotary spike, or row wheel into pre-irrigated or dry soil at three locations. The locations varied in type of soil, climatic conditions, and the species of broadleaf weeds. Rotary tiller incorporation generally resulted in best weed control with both spray and granular forms under all conditions. Herbicides usually performed best in pre-irrigated soil. Sprays and granules were equal in performance at coastal and intermediate locations; granules were more effective in the desert location. Herbicidal effectiveness was influenced by method of incorporation, form of treatment, soil moisture, environmental location, and weed type.

scholarly journals Hydrological functioning of forested catchments, Central Himalayan Region, India

2020 ◽  
Vol 7 (1) ◽  
Author(s):  
Nuzhat Qazi
Keyword(s):  
Soil Moisture ◽  
Water Discharge ◽  
Field Investigation ◽  
Himalayan Region ◽  
Annual Rainfall ◽  
Hydrological Response ◽  
Dry Period ◽  
Catchment Scale ◽  
Forested Catchments ◽  
Hydrological Functioning

Abstract Background Central Himalayan forested catchments provide fresh water supply and innumerable ecosystem services to millions of people. Hence, the understanding of linkages between forests and water is very crucial for availability and quality of water at catchment scale. Therefore, the present study aims to understand the hydrological response of two forested catchments (namely, Arnigad and Bansigad) in the Central Himalayan Region. Methods Three-years’ data (March, 2008 to February, 2011) were collected from meteorological and hydrological stations in Arnigad and Bansigad catchments. The present paper describes the mean hydrological response of these forested catchments investigated through detailed field investigation. Results The annual hyetograph analysis revealed that the rainfall at both the catchments was highly seasonal, and wet-period (June–September) plays a key role in catchment functioning. Exceedance of rainfall threshold of ~ 200 mm (~ 10% of annual rainfall) significantly increased streamflow generation in both catchments. In Arnigad, the stream was perennial with a mean baseflow of ~ 83 mm per month (~ 6% of annual baseflow) whereas, Bansigad had greater seasonality due to lack of streamflow during the pre-wet-period (March–May). Separation of hydrographs in Arnigad and Bansigad catchments i.e. stormflow (6% and 31%, respectively) and baseflow (50% and 32%, respectively) helped to understand the probability of flooding during wet-period and drought during dry-period. The forest ecosystem in Arnigad displayed healthier hydrological functioning in terms of reduced stormflow (82%), and enhanced baseflow (52%), soil moisture (13%), steady infiltration rate (22%) and lag time (~ 15 min) relative to Bansigad. These enhanced values indicated soil capability to store water in the forested catchment (Arnigad) and helped to understand the volume of water (discharge) that was available during dry-period. The lower denudation rate at Arnigad by 41% resulted in decreased suspended sediment (18%) and bed load (75%) compared to Bansigad. Further, the enhanced dissolved solids in the Arnigad stream resulted from the higher organic matter generated in the forest floor. Conclusion This study shows that rainfall during the wet-period was the main driver of hydrological functioning, whereas, forests provided substantial services by regulating water balance, soil moisture and sediment budget through different mechanisms of forest components at catchment-scale in the Central Himalayan Region.

scholarly journals Hydrological Functioning of Forested Catchments, Central Himalayan Region, India.

2020 ◽  
Author(s):  
Nuzhat Ul Qayoom Qazi
Keyword(s):  
Soil Moisture ◽  
Water Discharge ◽  
Field Investigation ◽  
Himalayan Region ◽  
Annual Rainfall ◽  
Hydrological Response ◽  
Dry Period ◽  
Catchment Scale ◽  
Forested Catchments ◽  
Hydrological Functioning

Abstract Background: Central Himalayan forested catchments provide fresh water supply and innumerable ecosystem services to millions of people. Hence, the understanding of linkages between forests and water is very crucial to recognize for availability and quality of water at catchment scale. Therefore, present study aims to understand hydrological response of two forested catchments (namely, Arnigad and Bansigad) in the Central Himalayan Region.Methods: Three-year data (March, 2008 to February, 2011) were collected from meteorological and hydrological stations installed at Arnigad and Bansigad catchments. The present paper displays mean hydrological response of forested catchments through detailed field investigation.Results : The annual hyetograph analysis revealed that the rainfall at both the catchments was highly seasonal, and wet-period (June-September) plays a key role in catchment functioning. Exceedance of rainfall threshold of ~200 mm (~10% of annual rainfall) significantly increased streamflow generation at both the catchments. At Arnigad, stream was perennial with a mean baseflow of ~83 mm per month (~ 6 % of annual baseflow) whereas, Bansigad had greater seasonality due to lack of streamflow during the pre-wet-period (March-May). Separation of hydrographs at Arnigad and Bansigad catchments i.e. stormflow (6% and 31%, respectively) and baseflow (50% and 32%, respectively) helped to understand the probability of flooding during wet-period and drought during dry-period. Forest ecosystem at Arnigad improved the hydrological functioning by: reducing stormflow (82%), and enhancing: baseflow (52%), soil moisture (13%), steady infiltration rate (22%) and lag time (~15 minutes) relative to Bansigad. These enhanced values indicated soil capability to store water at forested catchment (Arnigad) and helped to understand the volume of water (discharge) that was available during dry-period. The decrease of denudation rate (at Arnigad) by 41% resulted decrease in suspended sediment (18%) and bed load (75%) compared to Bansigad. Further, the enhancement of dissolved solids in stream resulted due to maximum organic matter generated in forest floor of Arnigad. Conclusion: This study accomplishes that rainfall during the wet-period was the main driver of hydrological functioning, whereas, forests provided substantial services by regulating water balance, soil moisture and sediment budget at Arnigad catchments through different mechanisms of forest components at catchment-scale in the Central Himalayan region.

Crop and Location Specific Agricultural Drought Quantification: Part II. Case Study

2017 ◽  
Vol 60 (3) ◽  
pp. 729-739 ◽  
Author(s):  
Rachel L. McDaniel ◽  
Clyde Munster ◽  
J. Tom Cothren
Keyword(s):  
Soil Moisture ◽  
Biomass Production ◽  
Drought Index ◽  
Swat Model ◽  
Growing Season ◽  
Moisture Stress ◽  
Agricultural Drought ◽  
Row Crops ◽  
Moisture Conditions

Abstract. An estimated 70% to 80% of water resources are used for agricultural production. Irrigation helps maintain adequate soil moisture for crops; however, drought can impact both the amount of water required for production and crop yields. Different crops are affected by moisture conditions in different ways, as some can handle lower moisture conditions better than others. There are many drought indices that quantify low-moisture conditions, but they are not crop-specific and therefore do not quantify moisture stress for a given crop. The goal of this study was to evaluate a crop-specific drought index by determining the index’s ability to reflect yield trends due to moisture conditions. The drought index is a weekly index that uses five variables: precipitation, temperature, biomass production, soil moisture, and transpiration. This article presents a case study that examines the effectiveness of the crop-specific drought index in determining moisture stress to crops by comparing the drought index with annual yield values. The site chosen for this study was the upper Colorado River basin (UCRB) in west Texas because it is prone to drought. Cotton is one of the most widely grown row crops in this region and was therefore used in this study. A hydrologic and crop model, the Soil Water Assessment Tool (SWAT), was used to determine the biomass production, soil moisture, and transpiration. Observed precipitation and temperature data were also used both in the SWAT model and in the drought index. A multiple linear regression model was created for each week of the growing season because each variable is important during different weeks of the growing season. For example, in the UCRB, soil moisture was found to be more important during the beginning of the growing season, while biomass production was found to be more important during the end of the growing season. Ultimately, the drought index was found to be a good indicator of moisture-related yield conditions, with an R2 of 0.67. This index can be used to assess moisture stress to agricultural crops and aid in management decisions related to irrigation timing. Keywords: Crop modeling, Drought, Drought index, Hydrologic modeling, SWAT, Water conservation, Water management, Water stress.

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