2011 Symposium on Data-Driven Approaches to Droughts Copyright (c) 2013 Purdue University All rights reserved. http://docs.lib.purdue.edu/ddad2011 Recent documents in 2011 Symposium on Data-Driven Approaches to Droughts en-us Thu, 24 Jan 2013 11:41:08 PST 3600 Drought Analysis Based on Copulas http://docs.lib.purdue.edu/ddad2011/45 http://docs.lib.purdue.edu/ddad2011/45 Mon, 29 Aug 2011 13:48:07 PDT Droughts produce a complex set of negative economic, environmental, and social impacts across a country or region. Using monthly standardized Precipitation Index (SPI) values, drought characteristics, namely, drought duration, severity, interval time and minimum SPI values, were determined. Two exponential distributions were used to model drought duration and interval time, respectively; gamma distribution was used to model for drought severity; and generalized Pareto distribution to model minimum SPI value. Several copulas in the Archimedean and meta-elliptical families were applied to construct four-dimensional joint distributions. The upstream Han River basin was selected as an example to illustrate the copulas. Results indicates that the Student copula was more appropriate for drought analysis in the selected area. Drought probabilities and return periods were calculated and analyzed based on the four-dimensional copula.

]]> Lu Chen et al. Developing A Regional Land Use Drought Index In Florida http://docs.lib.purdue.edu/ddad2011/44 http://docs.lib.purdue.edu/ddad2011/44 Mon, 29 Aug 2011 13:48:05 PDT Drought is a natural phenomenon that occurs when a significant decrease of water availability during a significant period of time and over a larger area. Drought indices can be a useful tool to assess and respond to drought. However, current drought indices could not fully show the land use effects and they have limitation in data sources. ENSO influence the climate of Florida; where El Niño years tend to be cooler and wetter, and La Niña years tend to be warmer and drier than normal in the fall through the spring, with the strongest effect in the winter. Both prolonged heavy rainfall and drought potentially have impacts on land uses and many aspects of Florida's economy and quality of life. Hence, understanding local ENSO patterns on regional scales and developing a new land use drought index in Florida are critical and necessary in agriculture and water resources planning and managements. This paper presents a 32 km high resolution land use adapted drought index on five different land uses (lake, urban, forest, wetland, and agriculture) in Florida based on the National Centers for Environmental Prediction (NCEP) North American Regional Reanalysis (RR) data from 1979 to 2002. The new regional land use drought indices were developed from normalized Bowen ratio and the results show that they could reflect not only the level of severity in drought events resulting from land use effects, but also La Niña driven drought impacts.

]]> Chi-Han Cheng et al. Bivariate drought analysis using entropy theory http://docs.lib.purdue.edu/ddad2011/43 http://docs.lib.purdue.edu/ddad2011/43 Mon, 29 Aug 2011 13:48:03 PDT Drought duration and severity are two properties that are usually needed for drought analysis. To characterize the correlation between the two drought properties, a bivariate distribution is needed. A new method based on entropy theory is proposed for constructing the bivariate distribution that is capable of modeling drought duration and severity with different marginal distributions. Parameters of the joint distribution are estimated with Newton’s method. Monthly streamflow data from Brazos River at Waco, Texas, are employed to illustrate the application of the proposed method to model drought duration and severity for drought analysis.

]]> Zengchao Hao et al. Analysis of Drought Severity and Duration Based on Runoff Derived from the Noah Land Surface Model http://docs.lib.purdue.edu/ddad2011/42 http://docs.lib.purdue.edu/ddad2011/42 Mon, 29 Aug 2011 13:48:01 PDT Water management requires, among other information, the proper identification of drought events and their characteristics: duration and severity. In this paper we compute standardized runoff index (SRI), which is an index based on runoff but computed following the same methodology as standardized precipitation index, over the Rio Grande basin. The runoff values were generated from the Noah land surface model. The drought duration and severity for each year were extracted and copula was used to produce the joint probabilities of drought severity and duration. Four copulas were tested and the Gumbel-Hougaard (GH) copula was deemed most appropriate for this dataset. The conditional probability distributions for severity given duration thresholds and duration given severity thresholds were also computed. This information can help water managers assess water availability and plan for extreme events accordingly.

]]> C Prakesh Khedun et al. Climatic characterization and response of water resources to climate change in limestone areas: some considerations on the importance of geological setting http://docs.lib.purdue.edu/ddad2011/41 http://docs.lib.purdue.edu/ddad2011/41 Mon, 29 Aug 2011 13:47:59 PDT It is worldwide recognized and accepted that, in Southern Europe and the Mediterranean area in the last hundred years, the atmospheric temperature has risen by about 1°C, accompanied by a general decrease in precipitation. The trends detected in historical thermo-pluviometric series recorded in South/Central Italy show a general decrease in precipitation on an annual scale and a concentration of negative trends in the months from October to March. Analysis of the Standard Precipitation Index for the period 1951-2008 indicates higher frequency and duration of droughts in the last two decades: four prolonged dry periods (each lasting for up to three years) have been recorded since 1988, whereas only two main droughts have been identified in the four decades between 1951 and 1988. Climate change greatly influences the hydrogeological processes regulating both groundwater and surface water availability. If the present trends should continue, a total yield of 10-20% less than at present should be expected in the next 50 years. This work analyses the response of springs fed by karst/fractured limestone aquifers, extensively outcropping in Central Italy, taken as representative region, to climatic variations. It is shown how groundwater regime, the discharge of springs and their response to climate change depend to a great extent on the geologic and structural setting of the system. Some of the examined springs are “local systems” which represent “overflow” of a “deeper regional flow” feeding larger “base springs”, often of poor quality (salty water), due to interactions with evaporite sediments of Triassic age. A dynamic groundwater divide, the position of which is greatly influenced by climate change, separates the recharge areas of base springs from those of local springs: as the piezometric surface is lowered, the watershed moves towards systems located at higher altitudes, producing a reduction in their recharge areas. Therefore, local springs connected to a base flow are more vulnerable to climate change than springs with recharge areas which do not feed a deep regional flow. The Bagnara and Lupa springs, taken as examples, have recharge areas with similar lithological, topographical and climate characteristics and similar mean discharges (about 120 l/s). In spite of this, only the discharge of the Bagnara spring, which is connected to a regional flow, fell dramatically during recent prolonged drought periods (e.g., 2001-2003 and 2006-2007). The results of the present research may be useful in studying hydrogeological processes in other limestone systems in climatically similar areas.

]]> Di Matteo Lucio et al. Drought Regionalization of Brazos River Basin Using an Entropy Approach http://docs.lib.purdue.edu/ddad2011/40 http://docs.lib.purdue.edu/ddad2011/40 Mon, 29 Aug 2011 13:47:57 PDT Assessment and understanding of past climate is an important step for drought mitigation and water resources planning. In this study, streamflow simulation obtained from the variable infiltration capacity (VIC) model was used for drought characterization, and subsequently regionalization was done based on the annual severity level, for the Brazos basin in Texas over a time span of 1949-2000. It is important to study drought characteristics within a regional context. Hence, identification of homogenous drought regions is a prerequisite, so that the drought characteristics can be studied within each of these regions. In this study, the concept of entropy was used for formation of homogenous regions based on drought severity. A standardized version of mutual information known as directional information transfer was used for station grouping. Results obtained were compared with the conventional k-means clustering method. The regions obtained were similar in both cases.

]]> Deepthi Rajsekhar et al. Innovative Management Systems to Cope with Drought: The Case of South-Western France http://docs.lib.purdue.edu/ddad2011/39 http://docs.lib.purdue.edu/ddad2011/39 Mon, 29 Aug 2011 13:47:55 PDT Water managers are increasingly aware of the problem of water scarcity and the randomness of rainfalls. This problem is exacerbated by recurrent droughts observed in south-western France in recent years where water consumption exclusively by agriculture often exceeds 80% in summer. In the given context of climate hazard, some management companies have introduced new water pricing methods with very specific features aiming particularly at a certain anticipation of the demand of irrigation water. The objective of this research is to analyze the effect induced by the application of these different water pricing methods on water demand, especially in case of drought, on farmers' income and on the revenue collected by the management company. To undertake this analysis a stochastic model that simulates farmers' behavior and their response to different water pricing scenarios has been built. Empirical application of the model has been carried out with the help of an agronomic model of plant growth and data collected from Midi-Pyrénées (France). The results show that these pricing policies create a wide range of effects that can be searched by management companies according to their characteristics and their access conditions to the resource. These pricing systems prove to be powerful tools to mitigate the impact of drought. This study provides very useful lessons for the design of water management policies.

]]> Yoro Sidibe et al. Analyzing Past and Predicting Future Drought with Comprehensive Drought Indices for Arkansas-Red River Basin http://docs.lib.purdue.edu/ddad2011/38 http://docs.lib.purdue.edu/ddad2011/38 Sun, 28 Aug 2011 19:16:42 PDT This study is intended to examine the past drought and predict future drought scenarios for Arkansas-Red River Basin with comprehensive drought indices ranging from meteorology, hydro-meteorology to hydrology. In this proceeding, we present some early results and analysis with the Standardized Precipitation Index (SPI) and the Palmer Drought Severity Index (PDSI). Historical climate data within the 1900-2009 timeframe were archived to derive the drought indices calculations. The projected A2, A1B climate data modules from 16 statistically downscaled Global Climate Models (GCM) were applied in drought occurrence frequency and affected area prediction. The results from the SPI and PDSI show that widespread drought took place in the 1910s, 1930s, 1950s and 1960s, which agrees with the historical climate record. Both the SPI and PDSI indicate more frequent droughts in the second part of the 21st century, but predictions from the two indices were carried out under different scenarios. The two indices describe future drought characteristics from a temporal and a spatial perspective. Future SPI values indicate that there might be a 110 year period of drought cycles occurring in the Arkansas-Red River Basin under A2, and future PDSI shows more severe droughts in the western portions of the basin under A1B.

]]> Lu Liu et al. Bivariate drought analysis using entropy theory http://docs.lib.purdue.edu/ddad2011/37 http://docs.lib.purdue.edu/ddad2011/37 Tue, 26 Jul 2011 12:55:16 PDT Drought analysis is important for water resources planning and management. Drought duration and severity are two main characteristics that have often been used for drought analysis, which can be defined using run theory with hydrological variables (e. g., streamflow).

A traditional way to characterize the drought duration or severity is based on fitting a probability density function. The drought duration can be modeled by a geometric distribution (discrete) or an exponential distribution (continuous). The gamma distribution is generally used to model drought severity.

Bivariate drought analysis is often needed to characterize the correlation between drought duration and severity. This article proposes a new method for constructing the joint density function of drought duration and severity with different marginal distributions based on the principle of maximum entropy. The proposed method is applied for drought analysis based on the monthly streamflow of Brazos River at Waco, Texas.

]]> Zengchao Hao et al. Innovative Management Systems to Cope with Drought: The Case of South-Western France http://docs.lib.purdue.edu/ddad2011/36 http://docs.lib.purdue.edu/ddad2011/36 Tue, 26 Jul 2011 12:55:14 PDT Water managers are increasingly aware of the problem of water scarcity and the randomness of rainfalls. This problem is exacerbated by recurrent droughts observed in south-western France. In the given context of climate hazard, some management companies have introduced new water pricing methods with very specific features aiming particularly at a certain anticipation of the demand of irrigation water. The objective of this research is to analyze the effect induced by the application of these different water pricing methods on water demand, especially in case of drought, on farmers' income and on there venue collected by the management company. To undertake this analysis a stochastic model that simulates farmers' behavior and their response to different water pricing scenarios has been built. Empirical application of the model has been carried out with the help of an agronomic model of plant growth and data collected from Midi-Pyrénées(France). The results show that these pricing policies create a wide range of effects that can be searched by management companies according to their characteristics and their access conditions to the resource. These pricing systems prove to be powerful tools to mitigate the impact of drought.

]]> Yoro Sidibe et al. Visualization-based Decision Tool for Urban Meteorological Modeling http://docs.lib.purdue.edu/ddad2011/35 http://docs.lib.purdue.edu/ddad2011/35 Tue, 26 Jul 2011 12:55:12 PDT Daniel G. Aliaga et al. Analyzing Past and Predicting Future Droughts with Comprehensive Drought Indices for Arkansas-Red River Basin http://docs.lib.purdue.edu/ddad2011/34 http://docs.lib.purdue.edu/ddad2011/34 Tue, 26 Jul 2011 12:55:11 PDT This study intends to examine the past and predict future drought scenarios for Arkansas-Red River Basin with comprehensive drought indices in areas of study including meteorology, hydrometeorology, and hydrology. In this proceeding, we present some early results and analysis with the Standardized Precipitation Index (SPI) and the Palmer Drought Severity Index (PDSI). Historical climate data of 1900-2009 were archived to derive the drought indices calculation as well as projected A2 and A1B climate data from 16 statistically downscaled Global Climate Models (GCM). These datasets were applied in drought occurrence frequency and affected area prediction. The results from SPI and PDSI show that widespread drought took place in the 1910s, 1930s, 1950s and 1960s, which agrees with the historical climate record. Both SPI and PDSI indicate more frequent droughts in the second part of the 21st century, but predictions from the two indices were carried out under different scenarios. Figure 1. Arkansas-Red River Basin (ABRFC) 1. Past and Future Climate •The temperature in the ABRFC displayed an upward trend after 2010 and it is projected to increase by 4-5 degrees by the end of the century. Precipitation however does not show a discernible trend overall, although the A2 scenario shows a slight decreasing trend after 2050. •The two indicators both capture the major droughts in the 1950s and the 1960s. SPI and PDSI agree quite well from 1950 to 1999 but not for the future period. •According to the SPI, ABRFC is under wet conditions for the first half of the 21st century, but precipitation becomes less abundant after 2060 which leads to a severe drought in the mid to late 2060s followed by another severe drought in the late 2070s. This indicates a possible drought cycle of 110 years looking back at the drought occurrence throughout 20th and 21st century. •According to PDSI, it appears that overall this region is going to get drier and the western portions of the ABRFC region will experience a more severe drought than the eastern portions during the next 90 years. The simulation does however indicate that a wetter period will occur from 2010 - 2039. SPI Values 2.0+ extremely wet 1.5 to 1.99 very wet 1.0 to 1.49 moderately wet -.99 to .99 near normal -1.0 to -1.49 moderately dry -1.5 to -1.99 severely dry -2 and less extremely dry Palmer Classifications 4.0+ extremely wet 3.0 to 3.99 very wet 2.0 to 2.99 moderately wet 1.0 to 1.99 slightly wet 0.5 to 0.99 incipient wet spell 0.49 to -0.49 near normal -0.5 to -0.99 incipient dry spell -1.0 to -1.99 mild drought -2.0 to -2.99 moderate drought -3.0 to -3.99 severe drought -4.0 and less extreme drought Table 3. SPI classification Table 4. PDSI classification Figure 2. Drought classification Drought index Inputs Indicator for SPI (Standardized Precipitation Index) Precipitation Meteorological drought PDSI (Palmar Drought Severity Index) Precipitation Temperature Meteorological drought Table 2. Drought indices information 2. Past and Future Drought Variables taken into account Complexity Cons SPI Precipitation Easier 1.Doesn’t consider evapotranspiration 2.Simple, not necessarily indicate drought 3.Requires quite a long period of precipitation record PDSI Precipitation and temperature More difficult 1.Sensitive to soil type 2.All precipitation is treated as rain 3.Underestimation of runoff 4.Potential evapotranspiration is estimated from Thornthwaite model 3. Comparison Data Source Data Parameters Resolution Time Period Data Type WCRP CMIP3 Precipitation Temperature 1/8 degree (~15 km) 1950-1999 (simulation) 2000-2099 (projection) Gridded monthly data PRISM Precipitation 4 km 1900-2000 (simulation) Gridded monthly data Table 1. Data used in research The two indices describe future drought from a temporal and a spatial perspective. Future SPI indicates there might be 110 years of drought cycles occurring in the Arkansas-Red River Basin under A2, and future PDSI shows more severe droughts in the western portions of the Arkansas-Red River Basin under A1B.

]]> Lu Liu et al. Climatic Characterization and Response of Water Resources to Climate Change in Limestone Areas: Some Consideration on the Importance of Geological Setting http://docs.lib.purdue.edu/ddad2011/33 http://docs.lib.purdue.edu/ddad2011/33 Fri, 22 Jul 2011 08:20:27 PDT The present study deals with the response of limestone aquifers to climate change. Central Italy is taken as representative region as characterized by extensive out cropping of karst/fractured limestones (Figure1),the aquifers of which supply several mountain springs having high quality water (Figure2). The recharge areas of mountain springs are virtually unaffected by human activity (no pumping wells): thus, the spring’s discharge analysis represents a useful tool to understand climate change and its effect on ground water regimes (Figure1). After climatic characterization of the Central Apenninearea on various time-scales (annual, seasonal and monthly), based on climate data for a 60-year period (1951-2008), the response of various springs to prolonged drought periods is analyzed in relationship to the geological setting of the irrecharge areas.

]]> Lucio Di Matteo Developing A Regional Land Use Drought Index In Florida http://docs.lib.purdue.edu/ddad2011/32 http://docs.lib.purdue.edu/ddad2011/32 Fri, 22 Jul 2011 08:20:26 PDT Chi-Han Cheng et al. Assessment of Climate Change Impacts on Drought Returns Periods Using Copula http://docs.lib.purdue.edu/ddad2011/31 http://docs.lib.purdue.edu/ddad2011/31 Fri, 22 Jul 2011 08:20:24 PDT Joint behavior of drought characteristics under climate change is evaluated using copula method which has recently attained popularity in analysis of complex hydrologic systems with correlated variables. Trivariate copulas are applied in this study to analyze the major drought variables; duration, severity, and intensity in the Upper Klamath River basin in Oregon. Results show that, among the variables, duration-severity is the most correlated pair whereas duration-intensity is the least correlated one. The impact of climate change on future droughts is evaluated using five Global Climate Models (GCMs) under one emission scenario. Comparing to the historical events, an overall decrease in drought duration and severity is estimated for the time period of 2020-2090 and the maximum duration is shown a decrease from 8 months to 5 months. Among the five GCMs employed in this study, GFDL-CM2.1 and CSIRO-MK3.0 are recognized as the wettest and driest projections, respectively. High uncertainty associated with GCM products is demonstrated in the analysis of return period by means of bivariate copulas; however, all projections result in larger return periods; i.e., less frequent droughts comparing to historical droughts during the reference period.

]]> Shahrbanou Madadgar et al. Drought Regionalization of Brazos River Basin Using an Entropy Approach http://docs.lib.purdue.edu/ddad2011/30 http://docs.lib.purdue.edu/ddad2011/30 Fri, 22 Jul 2011 08:20:23 PDT Assessment and understanding of past climate is an important step for drought mitigation and water resources planning. In this study, stream flows imulation obtained from the variable infiltration capacity(VIC) model was used for drought characterization, and subsequently regionalization was done based on the annual severity level, for the Brazos basin in Texas over a time span of 1949-2000. It is important to study drought characteristics with in a regional context. Hence, identification of homogenous drought regions is a prerequisite, so that the drought characteristics can be studied with in each of these regions. In this study, the concept of entropy was used for formation of homogenous regions based on drought severity. A standardized version of mutual information known as directional information transfer was used for station grouping. Results obtained were compared with the conventional k-means clustering method.

]]> Deepthi Rajsekhar et al. DRINET –an Online Drought Research and Collaboration Environment http://docs.lib.purdue.edu/ddad2011/29 http://docs.lib.purdue.edu/ddad2011/29 Fri, 22 Jul 2011 08:20:21 PDT DRINET is a research environment for collecting and disseminating local to regional scale drought information while interoperating with other resources and tools. The disseminated information via the DRINET will be based on a comprehensive evaluation of causal factors for short and long term droughts, as well as on a standardization of data formats and collection practices. It thus lays the foundation for investigating and providing improved drought risk and trigger indicators.

]]> Lan Zhao et al. Developing Metadata for the DRInet Repository http://docs.lib.purdue.edu/ddad2011/28 http://docs.lib.purdue.edu/ddad2011/28 Fri, 22 Jul 2011 08:20:19 PDT Jake R. Carlson A Hydroclimatological Assessment of the Regional Drought Vulnerability: Indiana Drought http://docs.lib.purdue.edu/ddad2011/27 http://docs.lib.purdue.edu/ddad2011/27 Fri, 22 Jul 2011 08:20:18 PDT Characterizing and developing drought climatology continues to be a challenging problem. Also as decision makers seek guidance on water management strategies, there is a need for assessing the performance of drought indices. This requires the adaptation of appropriate drought indices that aid in monitoring droughts and hydrological vulnerability on a regional scale. This study aims to assist the process of developing a statewide water shortage and assessment plan (WSP) for the state of Indiana, USA by conducting a focused hydroclimatological assessment of drought variability. Drought climatology was assessed using in-situ observations and regional reanalysis data. A summary of precipitation and evaporation trends, estimated drought variability, worst-case drought scenarios, drought return period, as well as frequency and duration was undertaken, using multiple drought indices and streamflow analysis. Results indicated a regional and local variability in drought susceptibility. The worst-case (200 year return period) prediction showed that Indiana has a 0.5% probability of receiving 45% of normal precipitation over a 12 month drought in any years. Consistent with other studies, the Standard Precipitation Index (SPI) was found to be appropriate for detecting short-term drought conditions over Indiana. This recommendation has now been incorporated in the 2009 Indiana Water Shortage Plan. This study also highlights the difficulties in identifying past droughts from available climatic data, and our results suggest a persistent, high degree of uncertainty in making drought predictions using future climatic projections.

]]> Umarporn Charusombat et al. Probabilistic Assessment of Drought Characteristics using a Hidden Markov Model http://docs.lib.purdue.edu/ddad2011/26 http://docs.lib.purdue.edu/ddad2011/26 Fri, 22 Jul 2011 08:20:16 PDT Droughts are evaluated using drought indices that measure the departure of meteorological and hydrological variables such as precipitation and stream flow from their long-term averages. While there are many drought indices proposed in the literature, most of them use pre-defined thresholds for identifying drought classes ignoring the inherent uncertainties in characterizing droughts. In this study, a hidden Markov model (HMM) [1] is developed for probabilistic classification of drought states. The HMM captures space and time dependence in the data. The proposed model is applied to assess drought characteristics in Indiana using monthly precipitation and stream flow data. The comparison of HMM based drought index with standard precipitation index (SPI) [2] suggests that the HMM index provides more intuitive results.

]]> Ganeshchandra Mallya et al.