Soil Chemical Analysis

The authors propose a new climatic drought index: the standardized precipitation evapotranspiration index (SPEI). The SPEI is based on precipitation and temperature data, and it has the advantage of combining multiscalar character with the capacity to include the effects of temperature variability on drought assessment. The procedure to calculate the index is detailed and involves a climatic water balance, the accumulation of deficit/surplus at different time scales, and adjustment to a log-logistic probability distribution. Mathematically, the SPEI is similar to the standardized precipitation index (SPI), but it includes the role of temperature. Because the SPEI is based on a water balance, it can be compared to the self-calibrated Palmer drought severity index (sc-PDSI). Time series of the three indices were compared for a set of observatories with different climate characteristics, located in different parts of the world. Under global warming conditions, only the sc-PDSI and SPEI identified an...

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A Multiscalar Drought Index Sensitive to Global Warming: The Standardized Precipitation Evapotranspiration Index

The Intergovernmental Panel on Climate Change (IPCC) Technical Paper Climate Change and Water draws together and evaluates the information in IPCC Assessment and Special Reports concerning the impacts of climate change on hydrological processes and regimes, and on freshwater resources – their availability, quality, use and management. It takes into account current and projected regional key vulnerabilities, prospects for adaptation, and the relationships between climate change mitigation and water. Its objectives are:

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Climate change and water.

More than 1.4 billion people depend on water from the Indus, Ganges, Brahmaputra, Yangtze, and Yellow rivers. Upstream snow and ice reserves of these basins, important in sustaining seasonal water availability, are likely to be affected substantially by climate change, but to what extent is yet unclear. Here, we show that meltwater is extremely important in the Indus basin and important for the Brahmaputra basin, but plays only a modest role for the Ganges, Yangtze, and Yellow rivers. A huge difference also exists between basins in the extent to which climate change is predicted to affect water availability and food security. The Brahmaputra and Indus basins are most susceptible to reductions of flow, threatening the food security of an estimated 60 million people.

http://science.sciencemag.org/content/sci/328/5984/1382.full.pdf

Climate change will affect the Asian water towers.

A remote sensing surface energy balance algorithm for land (SEBAL)-1. Formulation

Reference evapotranspiration (ET0)estimates have been computed on a globalscale using a high-resolution monthlyclimate dataset. Penman-Monteith (PM) andHargreaves (HG) methods have been compared,showing very reasonable agreement betweenthe two methods. Fitting the two parametersof HG using the PM derived ET0 valuesdid not improve estimates by the HG methodsubstantially. Modifying the originalHargreaves method to a Modified-Hargreaves(MH) method by including a rainfall termimproved ET0 estimates significantlyfor arid regions. When a certain level ofinaccuracy in the meteorologicalobservations was assumed, calculatingET0 by PM and MH, given theseinaccuracy in observations, showed that MHperformed better than PM in reproducingoriginal calculations of ET0 ascalculated by PM assuming no data error. Itis concluded that the PM is a recommendedmethodology if accurate weather datacollection can be expected, but otherwiseMH should be considered.

/pdf/estimating-reference-evapotranspiration-under-inaccurate-2vwinqzvj5.pdf

Peter Droogers

Papers

Estimating Reference Evapotranspiration Under Inaccurate Data Conditions

Large-scale monitoring of snow cover and runoff simulation in Himalayan river basins using remote sensing

Inverse method to determine soil hydraulic functions from multistep outflow experiments.

Calibration of a distributed hydrological model based on satellite evapotranspiration

Comparing evapotranspiration estimates from satellites, hydrological models and field data