scholarly journals Integrating MODIS images in a water budget model for dynamic functioning and drought simulation of a Mediterranean forest in Tunisia

2012 ◽  
Vol 9 (5) ◽  
pp. 6251-6284 ◽  
Author(s):  
H. Chakroun ◽  
F. Mouillot ◽  
M. Nouri ◽  
Z. Nasr
Keyword(s):  
Soil Water ◽  
Water Budget ◽  
Regional Scale ◽  
Field Capacity ◽  
Stress Index ◽  
Climatic Data ◽  
Natural Ecosystem ◽  
Stress Monitoring ◽  
Budget Model ◽  
Vegetation Stress

Abstract. The use of remote sensing at different spatio-temporal resolutions is being common during the last decades since sensors offer many inputs to water budget estimation. Various water balance models use the LAI as a parameter for accounting water interception, evapotranspiration, runoff and available ground water. The objective of the present work is to improve vegetation stress monitoring at regional scale for a natural forested ecosystem. LAI-MODIS and spatialized vegetation, soil and climatic data have been integrated in a water budget model that simulates evapotranspiration and soil water content at daily step. We first explore LAI-MODIS in the specific context of Mediterranean natural ecosystem. Results showed that despite coarse resolution of LAI-MODIS product (1 km), it was possible to discriminate evergreen and coniferous vegetation and that LAI values are influenced by underlying soil capacity of water holding. The dynamic of vegetation has been integrated into the water budget model by weekly varying LAI-MODIS. Results of simulations were analysed in terms of actual evapotranspoiration, deficit of soil water to field capacity and vegetation stress index based on actual and potential evapotranspiration. Comparing dynamic LAI variation, afforded by MODIS, to a hypothetic constant LAI all over the year correspond to 30% of fAPAR increase. A sensitivity analysis of simulation outputs to this fAPAR variation reveals that increase of both deficit of soil water to field capacity and stress index are respectively 18% and 27%, (in terms of RMSE, these variations are respectively 1258 mm yr−1 and 11 days yr−1). These results are consistent with previous studies led at local scale showing that LAI increase is accompanied by stress conditions increase in Mediterranean natural ecosystems. In this study, we also showed that spatial modelisation of drought conditions based on water budget simulations is an adequate tool for quantifying expositions of different species to stress and for analysing most influent factors on ecosystem vulnerability to drought.

OBSERVED AND ESTIMATED SEASONAL SOIL WATER VARIATIONS UNDER NONIRRIGATED SOD

1969 ◽  
Vol 49 (2) ◽  
pp. 181-188 ◽  
Author(s):  
W. Baier
Keyword(s):  
Soil Water ◽  
Water Budget ◽  
Soil Classification ◽  
Coefficient Of Determination ◽  
Standard Errors ◽  
Climatic Data ◽  
Wet Season ◽  
Total Period ◽  
Plant Soil ◽  
Available Soil Moisture

Variations of soil water content under nonirrigated sod at Ottawa during 10 seasons were analyzed using 5-day means of daily resistance readings from Colman units. A meteorological water budget making use of standard climatic data and accounting for physical properties of the soil provided estimates of soil water which resembled the measured values. The coefficient of determination for 5-day means of observed soil water, correlated with the estimates, varied from 0.34 in a wet season to 0.84 in a dry season, and was 0.73 over the whole 10-year period. Standard errors of estimates were between 4 and 25% of the seasonal mean of available soil moisture, and 15% for the total period. It was concluded that, for climatic and soil classification purposes, estimates from this meteorological budgeting technique are sufficiently accurate to be used for interpreting plant–soil–water interactions over past periods, for which climatological but not soil water observations are available.

Utility of a simple soil water budget model in agronomic research. 2. Estimates of available soil water in relation to profile changes of soil water content and potential

1974 ◽  
Vol 14 (66) ◽  
pp. 80 ◽  
Author(s):  
RG Fawcett ◽  
OG Carter
Keyword(s):  
Water Content ◽  
Soil Water ◽  
Soil Water Content ◽  
Water Budget ◽  
Plant Density ◽  
Budget Model ◽  
North West ◽  
The North ◽  
South Wales ◽  
Profile Changes

A study was made of the effects of plant density, time-of-sowing and level of fallow water on profile changes in soil water content and potential during the growing season of spring wheat. The pattern of soil moisture extraction was affected by all treatments although water depletion occurred chiefly in the 0-90 cm zone. The results are discussed in relation to limitations of a simple soil water budget model and to wheat cropping on the north-west slopes and plains of New South Wales.

Using a water budget model to anticipate the impact of climate change on groundwater recharge at the regional scale in cold and humid climates - example of southern Quebec (Canada)

2021 ◽  
Author(s):  
Emmanuel Dubois ◽  
Marie Larocque ◽  
Sylvain Gagné
Keyword(s):  
Climate Change ◽  
Groundwater Recharge ◽  
Water Budget ◽  
Regional Scale ◽  
Growing Season ◽  
Annual Precipitation ◽  
Climate Scenarios ◽  
Budget Model ◽  
Impact Of Climate Change ◽  
The Impact

<p>In cold and humid climates, rivers and superficial water bodies are often fed by groundwater with relatively constant inflows that are most visible during the summer (limited net precipitation) and the winter (limited runoff and infiltration). The harsh winter – short growing season succession could be drastically affected by climate change. Although water is abundant, extreme low flows are expected in the near future, most likely due to warmer summer temperatures, increased summer PET and possible lower summer precipitation. It is thus crucial to provide stakeholders with scenarios of future groundwater recharge (GWR) to anticipate the impacts of climate change on groundwater resources at the regional scale. This study aims to test the contributions of a superficial water budget model to estimate the impact of climate change on the regional GWR. The methodology is tested in a forested and agricultural region of southern Quebec, located between the St. Lawrence River and the Canada-USA border, and between the Quebec-Ontario border and Quebec City (36,000 km²). Scenarios of GWR for the region are simulated with the HydroBudget model, performing a transient-state spatialized superficial water budget, and 12 climate scenarios (RCP 4.5 and 8.5, 1951-2100 period). The model was previously calibrated in the study area for the 1961-2017 period and provides spatially distributed runoff, actual evapotranspiration, and GWR fluxes at a 500 x 500 m resolution with a monthly time step. Climate scenarios show warming of the annual temperature from +2 to +5°C and up to 20% increase of annual precipitation at the 2100 horizon compared to the 1981-2010 reference period. By the end of the century, the number of days above 0°C could double between November and April, dividing by almost two the quantity of snow during winter. The clear trends of warming temperature leads to a clear actual evapotranspiration (AET) increase while the increasing variability in annual precipitation translates into more variable annual runoff and GWR. Although no annual GWR decrease is simulated, an increase of winter GWR (up to x2) is expected, linked to warmer winters and unfrozen soils, followed by a decrease for the rest of the year, linked to a longer growing season producing higher AET rates. Although simple in its simulation process, the use of a superficial water budget model simulating soil frost provides new insights into the possible future trends in the different hydrologic variables based on a robust understanding of past condition. Aside from providing scenarios of spatialized GWR (also runoff and AET) at the 2100 horizon for a large region, this study shows that a simple water budget model is an appropriate and affordable tool to provide stakeholders with useful data for water management in a changing climate.</p>

Utility of a simple soil water budget model in agronomic research. 3. Estimation of the potential evapotranspiration function

1974 ◽  
Vol 14 (70) ◽  
pp. 684
Author(s):  
RG Fawcett ◽  
OG Carter
Keyword(s):  
Soil Water ◽  
Water Budget ◽  
Potential Evapotranspiration ◽  
Regression Equation ◽  
Wheat Crop ◽  
Budget Model ◽  
Plant Densities ◽  
Potential Transpiration

It has been shown that a regression equation relating the cumulative potential transpiration function (T/Eo) with the yield of tops, week of sowing and available fallow moisture, together with a simple budget model, can be used to estimate weekly changes in available soil water under a wheat crop. It is concluded from the data that use of the equation and budget model should be most suited to situations where plant densities are about 60 plants per m2 and the available fallow water is about 150 mm or less.

Utility of a simple soil water budget model in agronomic research. 1. Effects of plant density, time of sowing and fallow water on available soil water under spring wheat

1973 ◽  
Vol 13 (65) ◽  
pp. 714 ◽  
Author(s):  
RG Fawcett ◽  
OG Carter
Keyword(s):  
Soil Water ◽  
Spring Wheat ◽  
Water Budget ◽  
Field Experiments ◽  
Plant Density ◽  
New South ◽  
Growing Season ◽  
Wheat Cultivars ◽  
Budget Model ◽  
South Wales

A simple soil water budget model was used to estimate weekly changes in available soil water as affected by plant density, time of sowing and level of available fallow water for spring wheat cultivars grown on a black earth in northern New South Wales. Estimated values of available water were mostly within �10 mm of observed values (ranging from 50-270 mm) obtained at four intervals during the growing season. The results are discussed in relation to both the interpretation of agronomic field experiments and use of the model in regions where conserved fallow water contributes significantly to cereal production.

Forecasts of plant available and seepage water for agricultural usage during recent extreme hydrometeorological conditions in western Germany using a convection-permitting regional Earth-system model

2020 ◽  
Author(s):  
Alexandre Belleflamme ◽  
Klaus Goergen ◽  
Niklas Wagner ◽  
Sebastian Bathiany ◽  
Diana Rechid ◽  
...  
Keyword(s):  
Water Stress ◽  
Soil Water ◽  
Water Budget ◽  
Field Capacity ◽  
Earth System Model ◽  
System Model ◽  
Seepage Water ◽  
Earth System ◽  
Soil Layers ◽  
Fully Coupled

<p class="western" align="justify"><span lang="en-GB">The aim of the ADAPTER project (www.adapter-projekt.de) of the Helmholtz Association of German Research Centres is to develop products and usable information that help improve agriculture’s resilience to extreme weather conditions and climate change in Germany. One of the main hydrometeorological impacts on agriculture is the soil water budget. Here, we use the Terrestrial Systems Modelling Platform (TSMP) in forecast mode forced by ECMWF forecast data over a domain covering most of North-Rhine Westfalia (NRW, Germany). TSMP is a fully-coupled regional Earth system model with COSMO at 1km spatial resolution as the atmospheric component, with the Community Land Model (CLM) for the land surface interface, and ParFlow for the surface and sub-surface part of the water cycle, both models at 500m resolution. This allows a representation of the closed water budget, including three-dimensional sub-surface and groundwater flow. Here, we demonstrate the usefulness of the fully coupled TSMP for agriculture applications, by focussing on two fundamental parameters of the soil water budget: First, in the context of the droughts that affected Europe, and particularly Germany, over the summers 2018 and 2019, one major parameter for estimating and monitoring the water stress of plants is the fraction of plant available water (fPAW). The pressure head simulated by ParFlow is used to calculate fPAW, on the basis of soil parameters like porosity and the Van Genuchten equation. </span><span lang="en-GB">fPAW</span><span lang="en-GB"> is calculated over different soil depths from 0.1m to 3m, to provide information about the water stress of plants with different rooting depths. Our results show that the succession of extremely dry summers in 2018 and 2019, when the meteorological drought evolved into an agricultural and eventually into a hydrological drought, has led to very dry soils showing a fPAW below 30-50% over most of NRW, meaning that it became stressful for plants to extract water from the soil. This did not only affect the upper soil layers, as in 2018, but also deeper layers became very dry, thus no longer only impacting shallow root crops, but also plants with a higher root depth like trees. The wetter 2019 autumn allowed a recovery of the soil water content around the field capacity for the upper layers over a major part of the domain, while the deeper soil remains abnormally dry, especially in the south-western part of the domain. Second, knowing the amount of seepage water over a given period is not only important to monitor the groundwater recharge, which has become a major issue in the context of the past two summers, but also to estimate the leakage of nutrients and pollutants from the upper soil to deeper layers or even the groundwater in the context of certain environmental compliance issues. In accordance with the results obtained for fPAW, TSMP simulated seepage water flux during autumn 2019 only for the upper soil layers; this excessive water is only gradually percolating into deeper soil layers, which still remain clearly below the field capacity over a significant part of the domain.</span></p>

scholarly journals Simulation of long-term spatiotemporal variations in regional-scale groundwater recharge: Contributions of a water budget approach in southern Quebec

2021 ◽  
Author(s):  
Emmanuel Dubois ◽  
Marie Larocque ◽  
Sylvain Gagné ◽  
Guillaume Meyzonnat
Keyword(s):  
Time Series ◽  
Groundwater Recharge ◽  
Water Budget ◽  
River Flow ◽  
Regional Scale ◽  
Cold Climate ◽  
Budget Model ◽  
Precipitation Temperature ◽  
Spatially Distributed

Abstract. Groundwater recharge (GWR) is recognized to be a strategic hydrologic variable, necessary to estimate when implementing sustainable groundwater management, especially within a global change context. However, its simulation at the regional scale and for long-term conditions is challenging, especially due to the limited availability of spatially-distributed calibration data and to the rather short observed time series. The use of a superficial water budget model to estimate recharge is appropriate for this task. A reliable regional-scale estimate of GWR that can be updated relatively easily using widely-available data is essential for the implementation of long-term water use policies and is clearly lacking in southern Quebec (Canada; 36 000 km2). This study aims to test the ability of a spatially-distributed water budget model, automatically calibrated with river flow rates and baseflow estimates, to simulate GWR at a regional-scale from 1961 to 2017 in southern Quebec (monthly time step, 500 m × 500 m spatial resolution). The novelty of this work lies in the simulation of the first regional-scale GWR estimate for southern Quebec and in the development of a robust approach to implement a superficial water budget model at the regional-scale and for a long period. The HydroBudget model was specifically developed by a team at Université du Québec à Montréal for regional-scale simulation and cold climate conditions, and uses parsimonious input data (distributed precipitation, temperature, and runoff curve numbers). The model was regionally calibrated with river flows and baseflows (recursive filter on river flow data), and the automatic calibration procedure of the R package caRamel allowed a satisfying calibration quality (KGE = 0.72) to be reached. Across the study area and based on the exceptionally long spatialized time series, the simulated water budget was divided into 41 % runoff (444 mm/yr), 47 % actual evapotranspiration (501 mm/yr), and 12 % potential groundwater recharge (139 mm/yr). This partitioning was influenced by precipitation, temperature, soil texture, land cover, and topography. Groundwater recharge peaked during spring (44 % of annual recharge) and winter (32 % of annual recharge). A novel and particularly useful result from this work was to show that the seasonality of recharge was driven by the regional temperature gradient, with decreasing temperatures from west to east, and that winter GWR presented a statistically significant increasing trend since 1961 due to increased precipitation and warming temperatures. Another original contribution of this work was to show that at the regional scale, water budget models, such as HydroBudget, can be easily calibrated with river flow measurements and baseflows, and therefore represent a good option with which to acquire knowledge about regional hydrological dynamics. Being accessible, they are a useful approach for scientists, modellers, and stakeholders alike to understand regional-scale groundwater renewal rates, especially if they can be easily adapted to specific study needs and environments.

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