scholarly journals Rising temperature depletes soil moisture and exacerbates severe drought conditions across southeast Australia

2009 ◽  
Vol 36 (21) ◽  
Author(s):  
Wenju Cai ◽  
Tim Cowan ◽  
Peter Briggs ◽  
Michael Raupach
Keyword(s):  
Soil Moisture ◽  
Severe Drought ◽  
Southeast Australia ◽  
Drought Conditions

Dark Island heath (Ninety-mile Plain, South Australia). V. The water relationships in heath vegetation and pastures on the Makin sand

1957 ◽  
Vol 5 (2) ◽  
pp. 151 ◽  
Author(s):  
RL Specht
Keyword(s):  
Soil Moisture ◽  
Balance Sheet ◽  
South Australia ◽  
Field Capacity ◽  
Severe Drought ◽  
Soil Moisture Storage ◽  
Drought Conditions ◽  
Moisture Storage ◽  
Medicago Sativa L ◽  
Soil Moisture Status

Heath vegetation shows a major flush of growth during the mediterraneantype summer season, a time when calculations of the soil moisture storage by the techniques of Thornthwaite (1948) or Prescott, Collins, and Shirpurkar (1952) indicate that severe drought conditions should oocur. Monthly observations on the moisture status of the Makin sand under heath vegetation and, for comparison, under various pastures are therefore recorded. The problems of obtaining an accurate water balance-sheet for such a heterogeneous vegetation as the heath are discussed. Difficulties in the use of the various techniques for measuring soil moisture in sand, which has a low pF of 1.85 at field capacity, are enumerated. The following relationships were found between the evapotranspiration index (Itr = Etr / Ew0.75) and the available water (W). These data were calculated for 6 ft of sand. (i) Heath vegetation (10–14 years old) log (2.4–Itr) = 0.420–0.0383 W (ii) Heath vegetation (burnt) log (2.4–Itr) = 0.461–0.0380 W (iii) Oenothera odorata Jacq. pasture log (2.4–Itr) = 0.395–0.0269 W (iv) Medicago sativa L. pasture log (2.4–Itr) = 0.390–0.0270 W (v) Ehrharta calycina Sm. pasture log (2.4–Itr) = 0.400–0.0339 W From these equations the mean monthly quantities of rainfall which may be stored in 6 ft of sand under the various treatments described were calculated. Drought conditions are shown to occur in December and January, but are relieved in the later months of summer. Even if the stored moisture below 8 ft is considered, the soil moisture status would be expected to be just sufficient to maintain the vegetation in a "dormant" state, and yet the major growth of the heath vegetation occurs at this time. The calculated mean annual values of Itr range from 0.53 to 0.60 for these perennial communities. Close approximations to the actual soil moisture status can be obtained by substituting these values for K in Prescott's formula for potential evaporation, i.e. Etr = K x Ew0.75. Supplementary data on transpiration, growth, and the root systems of the pastures are also included.

scholarly journals Comprehensive evaluation of satellite-based and reanalysis soil moisture products using in situ observations over China

2021 ◽  
Author(s):  
Xiaolu Ling ◽  
Ying Huang ◽  
Weidong Guo ◽  
Yixin Wang ◽  
Chaorong Chen ◽  
...  
Keyword(s):  
Remote Sensing ◽  
Soil Moisture ◽  
Mainland China ◽  
Severe Drought ◽  
Weather Forecasts ◽  
European Centre ◽  
Drought Conditions ◽  
Medium Range

Abstract. Soil moisture (SM) plays a critical role in the water and energy cycles of the earth system; consequently, a long-term SM product with high quality is urgently needed. In this study, five SM products, including one microwave remote sensing product [European Space Agency's Climate Change Initiative (ESA CCI)] and four reanalysis datasets [European Centre for Medium-Range Weather Forecasts (ECMWF) Re-Analysis-Interim (ERAI), National Centers for Environmental Prediction (NCEP), the Twentieth Century Reanalysis Project from National Oceanic and Atmospheric Administration (NOAA) and the European Centre for Medium-Range Weather Forecasts Reanalysis 5 (ERA5)], are systematically evaluated using in situ measurements during 1981–2013 in four climate regions at different timescales over mainland China. The results show that ESA CCI is closest to the observations in terms of both the spatial distributions and magnitude of the monthly SM. All reanalysis products tend to overestimate soil moisture in all regions but have higher correlations than the remote sensing product except in Northwest China. The largest inconsistency is found in southern Northeast China, with a relative RMSE value larger than 0.1. However, none of the products can well reproduce the trends of interannual anomalies. The largest relative bias of 44.6 % is found for the ERAI SM product under severe drought conditions, and the lowest relative biases of 4.7 % and 9.5 % are found for the ESA CCI SM product under severe drought conditions and the NCEP SM product under normal conditions, respectively. As decomposing mean square errors in all the products suggests that the bias terms are the dominant contribution, the ESA CCI SM product is a good option for long-term hydrometeorological applications in mainland China. ERA5 is also a promising product, which is attributed to the incorporation of more observations. This long-term intercomparison study provides clues for SM product enhancement and further hydrological applications.

Variability in the Environmental Factors Driving Evapotranspiration from a Grazed Rangeland during Severe Drought Conditions

2007 ◽  
Vol 8 (2) ◽  
pp. 207-220 ◽  
Author(s):  
Joseph G. Alfieri ◽  
Peter D. Blanken ◽  
David N. Yates ◽  
Konrad Steffen
Keyword(s):  
Soil Moisture ◽  
Environmental Factors ◽  
Moisture Content ◽  
Land Surface ◽  
Soil Moisture Content ◽  
Severe Drought ◽  
Vapor Transfer ◽  
Drought Conditions ◽  
Using Data

Abstract Nearly one-half of the earth’s terrestrial surface is susceptible to drought, which can have significant social, economic, and environmental impacts. Therefore, it is important to develop better descriptions and models of the processes linking the land surface and atmosphere during drought. Using data collected during the International H2O Project, the study presented here investigates the effects of variations in the environmental factors driving the latent heat flux (λE) during drought conditions at a rangeland site located in the panhandle of Oklahoma. Specifically, this study focuses on the relationships of λE with vapor pressure deficit, wind speed, net radiation, soil moisture content, and greenness fraction. While each of these environmental factors has an influence, soil moisture content is the key control on λE. The role of soil moisture in regulating λE is explained in terms of the surface resistance to water vapor transfer. The results show that λE transitioned between being water or energy limited during the course of the drought. The implications of this on the ability to understand and model drought conditions and transitions into or out of droughts are discussed.

Effect of Soil Moisture on Atrazine and Cyanazine Persistence and Injury to Subsequent Cereal Crops in Southern Alberta

1993 ◽  
Vol 7 (4) ◽  
pp. 988-994 ◽  
Author(s):  
Jim R. Moyer ◽  
Robert E. Blackshaw
Keyword(s):  
Soil Moisture ◽  
Cereal Crops ◽  
Severe Drought ◽  
Exponential Equation ◽  
Southern Alberta ◽  
Drought Conditions ◽  
Accumulated Rainfall ◽  
One Year

One year after application under irrigated conditions, atrazine at 1.2 kg/ha injured oat but there was no effect after two years. On dryland, wheat and barley were injured for up to two years after atrazine was applied at 1.5 kg/ha. Atrazine concentrations in the soil were related to accumulated rainfall in an exponential equation. The equation predicted that, under the most severe drought conditions ever recorded for southern Alberta, injury to cereal crops could occur for at least three years after atrazine application at 1.2 to 1.5 kg/ha. Cyanazine did not injure subsequent crops under either irrigated or dryland conditions.

Peat Wedges Aid Seedling Establishment on Shallow Soil

1976 ◽  
Vol 52 (2) ◽  
pp. 47-52
Author(s):  
George Stroempl
Keyword(s):  
Soil Moisture ◽  
Seedling Establishment ◽  
Tree Planting ◽  
Severe Drought ◽  
Full Potential ◽  
Stages Of Growth ◽  
Growing Seasons ◽  
Shallow Soil ◽  
Drought Conditions ◽  
Limestone Bedrock

Tree planting experiments were established in south-eastern Ontario on old pastures with shallow soil over limestone bedrock known to have frequent moisture deficits during the growing seasons. Wedge-shaped pieces of solid peat, saturated with water, were placed at the bottom of a planting hole to supply water to the roots during the early stages of growth and prevent dessiccation during severe drought conditions. The survival of trees planted with peat wedges was higher than those planted without, particularly in the year when soil moisture was most frequently within the wilting range. Additional experience is needed to realize the full potential of this method.

scholarly journals Drought Assessment in the São Francisco River Basin Using Satellite-Based and Ground-Based Indices

2021 ◽  
Vol 13 (19) ◽  
pp. 3921
Author(s):  
Franklin Paredes-Trejo ◽  
Humberto Alves Barbosa ◽  
Jason Giovannettone ◽  
T. V. Lakshmi Kumar ◽  
Manoj Kumar Thakur ◽  
...  
Keyword(s):  
Soil Moisture ◽  
River Basin ◽  
Mitigation Strategies ◽  
Agricultural Drought ◽  
Extreme Drought ◽  
Severe Drought ◽  
Sao Francisco River ◽  
São Francisco River ◽  
Groundwater Drought ◽  
Drought Conditions

The São Francisco River Basin (SFRB) plays a key role for the agricultural and hydropower sectors in Northeast Brazil (NEB). Historically, in the low part of the SFRB, people have to cope with strong periods of drought. However, there are incipient signs of increasing drought conditions in the upper and middle parts of the SFRB, where its main reservoirs (i.e., Três Marias, Sobradinho, and Luiz Gonzaga) and croplands are located. Therefore, the assessment of the impacts of extreme drought events in the SFRB is of vital importance to develop appropriate drought mitigation strategies. These events are characterized by widespread and persistent dry conditions with long-term impacts on water resources and rain-fed agriculture. The purpose of this study is to provide a comprehensive evaluation of extreme drought events in terms of occurrence, persistence, spatial extent, severity, and impacts on streamflow and soil moisture over different time windows between 1980 and 2020. The Standardized Precipitation-Evapotranspiration Index (SPEI) and Standardized Streamflow Index (SSI) at 3- and 12-month time scales derived from ground data were used as benchmark drought indices. The self-calibrating Palmer Drought Severity Index (scPDSI) and the Soil Moisture and Ocean Salinity-based Soil Water Deficit Index (SWDIS) were used to assess the agricultural drought. The Water Storage Deficit Index (WSDI) and the Groundwater Drought Index (GGDI) both derived from the Gravity Recovery and Climate Experiment (GRACE) were used to assess the hydrological drought. The SWDISa and WSDI showed the best performance in assessing agricultural and hydrological droughts across the whole SFRB. A drying trend at an annual time scale in the middle and south regions of the SFRB was evidenced. An expansion of the area under drought conditions was observed only during the southern hemisphere winter months (i.e., JJA). A marked depletion of groundwater levels concurrent with an increase in soil moisture content was observed during the most severe drought conditions, indicating an intensification of groundwater abstraction for irrigation. These results could be useful to guide social, economic, and water resource policy decision-making processes.

scholarly journals Multi-Dimensional Drought Assessment in Abbay/Upper Blue Nile Basin: The Importance of Shared Management and Regional Coordination Efforts for Mitigation

2021 ◽  
Vol 13 (9) ◽  
pp. 1835
Author(s):  
Yared Bayissa ◽  
Semu Moges ◽  
Assefa Melesse ◽  
Tsegaye Tadesse ◽  
Anteneh Z. Abiy ◽  
...  
Keyword(s):  
Soil Moisture ◽  
Regional Scale ◽  
Earth Observation ◽  
Drought Indices ◽  
Severe Drought ◽  
Nile Basin ◽  
Blue Nile ◽  
Blue Nile Basin ◽  
Small Streams ◽  
Upper Blue Nile Basin

Drought is one of the least understood and complex natural hazards often characterized by a significant decrease in water availability for a prolonged period. It can be manifested in one or more forms as meteorological, agricultural, hydrological, and/or socio-economic drought. The overarching objective of this study is to demonstrate and characterize the different forms of droughts and to assess the multidimensional nature of drought in the Abbay/ Upper Blue Nile River (UBN) basin and its national and regional scale implications. In this study, multiple drought indices derived from in situ and earth observation-based hydro-climatic variables were used. The meteorological drought was characterized using the Standardized Precipitation Index (SPI) computed from the earth observation-based gridded CHIRPS (Climate Hazards Group InfraRed Precipitation with Station) rainfall data. Agricultural and hydrological droughts were characterized by using the Soil Moisture Deficit Index (SMDI) and Standardized Runoff-discharge Index (SRI), respectively. The monthly time series of SMDI was derived from model-based gridded soil moisture and SRI from observed streamflow data from 1982 to 2019. The preliminary result illustrates the good performance of the drought indices in capturing the historic severe drought events (e.g., 1984 and 2002) and the spatial extents across the basin. The results further indicated that all forms of droughts (i.e., meteorological, agricultural, and hydrological) occurred concurrently in Abbay/Upper Blue Nile basin with a Pearson correlation coefficient ranges from 0.5 to 0.85 both Kiremt and annual aggregate periods. The concurrent nature of drought is leading to a multi-dimensional socio-economic crisis as indicated by rainfall, and soil moisture deficits, and drying of small streams. Multi-dimensional drought mitigation necessitates regional cooperation and watershed management to protect both the common water sources of the Abbay/Upper Blue Nile basin and the socio-economic activities of the society in the basin. This study also underlines the need for multi-scale drought monitoring and management practices in the basin.

scholarly journals Investigating the Spatio-Temporal Variation of Soil Moisture and Agricultural Drought towards Supporting Water Resources Management in the Red River Basin of Vietnam

2021 ◽  
Vol 13 (9) ◽  
pp. 4926
Author(s):  
Nguyen Duc Luong ◽  
Nguyen Hoang Hiep ◽  
Thi Hieu Bui
Keyword(s):  
Soil Moisture ◽  
River Basin ◽  
Temporal Dynamics ◽  
Regional Scale ◽  
Dry Season ◽  
Red River ◽  
Agricultural Drought ◽  
Severe Drought ◽  
Red River Basin ◽  
Spatio Temporal

The increasing serious droughts recently might have significant impacts on socioeconomic development in the Red River basin (RRB). This study applied the variable infiltration capacity (VIC) model to investigate spatio-temporal dynamics of soil moisture in the northeast, northwest, and Red River Delta (RRD) regions of the RRB part belongs to territory of Vietnam. The soil moisture dataset simulated for 10 years (2005–2014) was utilized to establish the soil moisture anomaly percentage index (SMAPI) for assessing intensity of agricultural drought. Soil moisture appeared to co-vary with precipitation, air temperature, evapotranspiration, and various features of land cover, topography, and soil type in three regions of the RRB. SMAPI analysis revealed that more areas in the northeast experienced severe droughts compared to those in other regions, especially in the dry season and transitional months. Meanwhile, the northwest mainly suffered from mild drought and a slightly wet condition during the dry season. Different from that, the RRD mainly had moderately to very wet conditions throughout the year. The areas of both agricultural and forested lands associated with severe drought in the dry season were larger than those in the wet season. Generally, VIC-based soil moisture approach offered a feasible solution for improving soil moisture and agricultural drought monitoring capabilities at the regional scale.

How do lichens survive severe drought conditions?

Mycologist ◽  
1996 ◽  
Vol 10 (2) ◽  
pp. 89-90
Author(s):  
Susan Isaac
Keyword(s):  
Severe Drought ◽  
Drought Conditions
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