Dragon drought monitoring

Researchers:	Bob Su
	Rogier van der Velde
	Tom Rientjes

Organisations:	Department of Water Resources, ITC

Funding:	ESA-NRSCC Dragon Programme
	ITC IRF

Period:	2005 – 2007

Background

Drought disasters have often caused great hunger, social instability, large scale migration of the population and the distinction of civilizations in the history. The conflict between supply and demand of water resources constitutes the biggest problem for food security of a huge population in China and drought has become a key factor constraining China's economic development.

Objectives

The objective of this project is to develop an operational system for nation wide drought monitoring and drought impact assessment for application in agriculture and hydrology in China using ESA and other relevant satellite data as major data source in combination with other data source (e.g. meteorological and drought statistics, etc.).

In detail the project will generate:

-	scientifically based drought mitigation and drought relief decision alternatives,

-	real time drought monitoring and prediction maps,

-	improved understanding of land surface processes over heterogeneous terrain,

-	algorithms for estimation of land surface parameters and heat fluxes over China,

-	assessment of economic loss caused by drought and finally providing suggestions for drought relief decisions.

An Internet based system will be developed to provide information concerning the drought evolution situation and to support drought relief decision-making. The system will be implemented at the Remote Sensing Application Center of the Ministry of Agriculture and can be accessed in real time by decision-making agencies at different levels (national, provincial, local authorities) via Internet.

This project will be implemented during the whole period of the Dragon programme (2004 -2007). The following general schedule will be followed:

-	2004: Identification of data requests, conduction of field experiments, identification of requirements for algorithms and data processing procedures, reporting

-	2005: Development of validation of algorithms, conduction of field experiments for calibration and validation purposes, data processing, training of technical personnel, reporting.

-	2006: Data processing, conduction of specific field experiments for validation purposes, set-up of operational processing chain, training of technical personnel, reporting.

-	2007: Set-up of web based information drought monitoring system, Operational data processing, validation of data products, consultation with end users.

Methodology

The main methodologies to be applied include:

Approach 1:

-	To derive relative evaporation & relative soil moisture in the root zone from land surface energy balance (Su et al., 2003a,b)

-	To define a quantitative drought severity index (DSI) for large scale drought monitoring (Su et al., 2003a,b)

-	Time series analysis to produce consistent DSI maps using the HANTS algorithm (Verhoef et al., 1996; Roerink et al., 2000).

-	This approach uses chiefly data from VIS, NIR, SWIR and TIR, in combination with meteorological information.

Approach 2:

-	To determine surface soil moisture (Wen and Su, 2003, 2004)

-	To assimilate surface SM into a hydrological model to derive root soil moisture (Troch et al., 2003)

-	This approach uses microwave data to infer near surface soil moisture which must be translated into soil moisture information in the entire root zone via data assimilation. For this purpose a physically based hydrological model is necessary.

A critical element in both approaches is the ability to validate the methodologies on the basis of large scale field experiments. To this purpose, dedicated field experiments will be organised both in China and Europe for the development and validation of algorithms. In combination with ongoing activities and data availability, 3 sites in Europe (Barrax in Spain, Cabauw and Loobos in the Netherlands) and 5 sites in China (CAMP/Tibet site, The Heihe Oasis-Desert Site, Luancheng agro-ecological Observation Station (Hebei), CAS Xiaotangshan & Shunyi Field experiment sites in Beijing, and The Yellow River Headwater Site).

Data sets

The data to be used include EO and other data.

EO data (Including):

-	ENVISAT MERIS, AATSR, ASAR level 1b data (ASAR Alternating Polarisation modes):

for detailed analysis at selected experimental sites for algorithm development and validation. These data are required for all 3 European (E1-3, see appendix for derails) and 5 Chinese sites (C1-5). These data should be acquired over these site whenever possible. Historical ERS-1/2 datasets (ATSR, WSC) are also requested for retrospective analysis.

-	TERRA/AQUA-MODIS and ENVISAT/MERIS, AATSR, ASAR level 2 data (ASAR Global Monitoring modes):

-	for Albedo, vegetation variables (vegetation index, LAI when available) and surface temperature covering the whole country, and

-	for nation-wide monitoring of drought situation and detection of most fragile areas to severe drought.

In addition, ERS-1/2 WSC data are also requested for China. ENVISAT level 2 products will be validated and compared to products derived using specific algorithms developed in this project at the validation sites (E1-3, C1-5). Applications of these data will be made at all the demonstration sites (D1-13).

Other data (data provider, including):

-	Background information database from local to national level, including spatial distribution of arable land, digital soil maps, land use, hydrological data, crop yields, other general socio-economic parameters like population, income or etc. (CAAS)

-	Nationwide meteorological data (historical and real time) (NMC)

-	Experimental database for all experimental sites (site PIs)

-	Reanalysis data (ER40) from ECMWF (ITC)

-	DEM over China (ITC, CUG)

-	NOAA AVHRR data (ITC, VU)