Drought Watch Research Articles

Building Capacity for a User-Centred Integrated Early Warning System for Drought in Papua New Guinea

Drought has significant impacts on the agricultural productivity and well-being of Pacific Island communities. In this study, a user-centred integrated early warning system (I-EWS) for drought was investigated for Papua New Guinea (PNG). The I-EWS combines satellite products (Standardised Precipitation Index and Vegetation Health Index) with seasonal probabilistic forecasting outputs (chance of exceeding median rainfall). Internationally accepted drought thresholds for each of these inputs are conditionally combined to trigger three drought early warning stages—”DROUGHT WATCH”, “DROUGHT ALERT” and “DROUGHT EMERGENCY”. The developed I-EWS for drought was used to examine the evolution of a strong El Niño-induced drought event in 2015 as well as a weaker La Niña-induced dry period in 2020. Examining the evolution of drought early warnings at a provincial level, it was found that tailored warning lead times of 3–5 months could have been possible for several impacted PNG provinces. These lead times would enable increasingly proactive drought responses with the potential for prioritised allocation of funds at a provincial level. The methodology utilised within this study uses inputs that are openly and freely available globally which indicates promising potential for adaptation of the developed user-centred I-EWS in other Pacific Island Countries that are vulnerable to drought.

Suomi NPP/VIIRS: improving drought watch, crop loss prediction, and food security

Since 1990, the role of satellite observations for climate and land services increased considerably, especially with the introduction in 2011 of the new generation of NOAA operational satellites, called Suomi NPOSS Polar-Orbiting Partnership (S-NPP). S-NPP will continue as the Joint Polar Satellite System (JPSS) for the next two decades. The Visible Infrared Imaging Radiometer Suite (VIIRS) on the S-NPP spacecraft is accommodating the best technical and scientific features of its predecessors and has several new important features. S-NPP and JPSS, in addition to data collection, will address the impacts of climate and weather on industries, water, energy, population health, and other resources and activities. This article discusses how these operational satellites improve early drought detection, monitoring its features (intensity, duration, area, etc.) and prediction of agricultural losses; how fast the Earth’s natural resources deteriorate; and whether the current warm climate intensifies droughts and increases its area and duration. These climate services have already become available to the global community (http://www.star.nesdis.noaa.gov/smcd/emb/vci/VH/index.php). The S-NPP/VIIRS data permits its users to enhance long-term environmental data records, thereby improving the ability to estimate global warming, land-cover changes, and better monitoring of environmental resources.

Drought onset and recovery over the United States

[1] This study employs precipitation (P) and ensemble soil moisture data sets from 1916 to 2007 to study the drought onset and demise over the United States. Both meteorological drought, classified using the standardized precipitation indices (SPIs), and agricultural drought, classified using the soil moisture percentiles, are studied. Drought onset is more predictable than drought demise. It takes 5–8 months for a region to accumulate enough P deficits to begin a drought, whereas a drought demise can come within one month to one season. A few strong rainfall episodes can end drought. The preferred season for the meteorological drought onset is at the beginning of the rainy season. Even though drought has a preferred season to begin, the ratio between the onset occurring in that season and the total drought events is less than 45%. For agricultural drought, the ratio is 60% or higher for the northwestern interior states and the Southwest. Over the Southern Plains, a cold El Nino–Southern Oscillation (ENSO) event occurs one season before the onset of drought. No drought events occur during the warm ENSO years. Therefore, the occurrence of a cold ENSO event can serve as an early warning for drought. For other areas influenced by ENSO, such as the lower Mississippi basin, the Ohio Valley, the Pacific Northwest, the upper Missouri basin, and the Southeast, most drought events occur during ENSO. The one-to-one correspondence between ENSO and drought is not good. For these areas, ENSO can only serve as a signal for intensive drought watch.

The analysis of the Standardized Precipitation Index in the Mediterranean area: large-scale patterns

Problems related to the identification and monitoring of drought are investigated. In particular, drought conditions in Italy are examined using the Standardized Precipitation Index (SPI) on different time scales for August 2000. Historical reconstruction of drought events is also shown for particular locations of Italy for the last fifty years. These preliminary applications show interesting results and demonstrate that the index considered is a tool that should be used operationally as part of a national drought watch system in Italy to monitor drought conditions objectively. An example of a monthly bulletin of drought for Italy is also shown.

Assessment of Hydrological Drought Revisited

A variety of indices for characterising hydrological drought have been devised which, in general, are data demanding and computationally intensive. On the contrary, for meteorological droughts very simple and effective indices such as the Standardised Precipitation Index (SPI) have been used. A methodology for characterising the severity of hydrological droughts is proposed which uses an index analogous to SPI, the Streamflow Drought Index (SDI). Cumulative streamflow is used for overlapping periods of 3, 6, 9 and 12 months within each hydrological year. Drought states are defined which form a non-stationary Markov chain. Prediction of hydrological drought based on precipitation is also investigated. The methodology is validated using reliable data from the Evinos river basin (Greece). It can be easily applied within a Drought Watch System in river basins with significant storage works and can cope with the lack of streamflow data.

Integrated Drought Watch System: A Case Study in Southern Italy

Drought is a natural hazard with varying patterns in space, time, and intensity. Because of the spatial and temporal variability and multiple impacts of drought, it is necessary to improve tools and data available for mapping and monitoring this phenomenon on all scales. Starting from some initiatives promoted by the European Community, an integrated drought watch system aimed at analysing and forecasting the effects produced by prolonged water deficit periods has been developed in southern Italy. Using GIS technologies integrated with tele-metering network, hydrological databases and distributed water balance models, it allows the analysis of different aspects of the wider drought phenomenon. Specifically, meteorological, agricultural and hydrological aspects have been together considered in a common framework according to the features required by Web-GIS applications with the aim of using Internet as a diffusion tool of the spatially distributed information managed by the system. In this paper, after a brief description of the drought watch system functionalities, the capability of detecting severe and prolonged water deficit periods have been verified in two regions in southern Italy during the last decade, considering meteorological and satellite indices together with the principal water balance components. The analysis carried out on the study area pointed out an extremely intense drought phenomenon during the period 1996–2002, characterised by a reduction in precipitation together with higher evapotranspiration values and, as a consequence, by a broad decrease in surface and groundwater runoff.

가뭄 예ㆍ경보에 의한 저수지 운영에 관한 연구

본 연구는 유역의 가뭄 예ㆍ경보 기준을 사용한 저수지 운영과 저수지의 운영률을 수행한 결과를 비교하여, 보다 효율적인 저수지 운영방안을 검토하였다. 그 결과 가뭄 예ㆍ경보 시스템과 방류계수를 사용한 저수지 운영이 기존의 저수지 운영률을 사용한 저수지 운영에 비하여 신뢰도와 연평균 저류량이 향상됨을 확인할 수 있었다. 시범유역으로 선정된 금강유역의 용담댐에서 저수지 운영시 사용할 방류계수로는 가뭄주의일 때 0.95, 가뭄경보일 때 0.9, 가뭄비상일 때 0.85의 값이 가장 효율적인 것으로 검토되었다. 가뭄 예<TEX>$\cdot$</TEX>경보를 사용한 저수지 운영은 가뭄시 수자원의 효율적인 이용을 가능하게 하며, 국가 수자원 관리에 크게 이바지할 것으로 판단된다. In this study, the efficient reservoir operation is studied by comparing results from reservoir operation using a basin drought forecasting and warning system with an existing reservoir operation rule. As a result, it is found that the reliability and average annual storage of reservoir operation using a basin drought forecasting and warning system and release coefficients is better than those of reservoir operation using the existing operation rule. The release coefficients for Yongdam dam located in the Geum river basin selected as a case study are found to be the most effective for the value of 0.95 for the drought watch, 0.9 for the drought warning and 0.85 for the drought emergency. The reservoir operation using a drought forecasting and warning enables the use of the limited water resources effectively during drought and will contribute the national water resources management.

A drought early warning system on real‐time multireservoir operations

A color‐coded early warning system is developed and proposed for drought management on the real‐time reservoir operation. The system consists of three essential elements, namely, (1) drought watch, (2) water consumption measure, and (3) policy making. A new drought alert index is used to characterize the alert level of drought severity. For demonstration the drought warning procedures were effectively applied to a real‐world two‐parallel‐reservoir region in northern Taiwan. The implementation of such a system proves that the decision support‐like system can help the water authorities concerned take a timely action while confronting drought threats.

Towards a Drought Watch System based on Spatial SPI

Regional Drought can be assessed through various meaningfulprocedures mainly related to the expected consequences. However, a general knowledge of the occurrence of drought, thearea which is affected, its severity and its duration are ofgreat importance for a series of decisions, which may beappropriate for a variety of activities. From the existingsimple and popular indices used for the estimation of drought,the Standardised Precipitation Index, known as SPI, seems to winuniversal applicability. A method based on the estimation of SPIover a geographical area and its use for characterising drought,is presented in this paper. Applications of the method arepresented using a digital terrain model and a simple computercalculating routine. It is shown that the proposed procedurecan be easily applied and can support a Drought Watch System foran area of mesoscale dimensions.

RESPONDING TO DROUGHT: COMMON THREADS FROM THE PAST, VISIONS FOR THE FUTURE

ABSTRACT: A number of studies conducted since the late 1970s have evaluated state and federal responses to drought in the United States. Each of these studies identified a number of key issues and impediments that needed to be addressed to improve the nation's ability to cope with and prepare for future episodes of drought. A content analysis of these studies was performed to identify common threads in their recommendations. The premise of this analysis was that the series of drought years that occurred between 1986 and 1992 and recurred between 1994 and 1996 increased awareness of our nation's continuing and apparent growing vulnerability to drought. This awareness has led to greater consensus among principal constituents and stakeholders, and also a greater sense of urgency to implement actions now to lessen vulnerability. The results of this analysis revealed that several themes recur: create an integrated national drought policy and plan; develop an integrated national climate monitoring (drought watch) system; incorporate drought in FEMA's National Mitigation Strategy; conduct post-drought audits of response efforts; establish regional drought forums; and encourage development of state drought mitigation plans.

Global Drought Watch from Space

Abstract Drought is the most damaging environmental phenomenon. During 1967–91, droughts affected 50% of the 2.8 billion people who suffered from weather-related disasters. Since droughts cover large areas, it is difficult to monitor them using conventional systems. In recent years the National Oceanic and Atmospheric Administration has designed a new Advanced Very High Resolution Radiometer- (AVHRR) based Vegetation Condition Index (VCI) and Temperature Condition Index (TCI), which have been useful in detecting and monitoring large area, drought-related vegetation stress. The VCI was derived from the Normalized Difference Vegetation Index (NDVI), which is the ratio of the difference between AVHRR-measured near-infrared and visible reflectance to their sum. The TCI was derived from the 10.3–11.3-mm AVHRR-measured radiances, converted to brightness temperature (BT). Algorithms were developed to reduce the noise and to adjust NDVI and BT for land surface nonhomogeneity. The VCI and TCI are used to determine...